RESEARCH ARTICLE

Inflammation, aging, and cancer vaccines

Mauro Provinciali • Alessandra Barucca •

Maurizio Cardelli • Francesca Marchegiani •

Elisa Pierpaoli

Received: 25 February 2010 / Accepted: 27 April 2010 / Published online: 9 May 2010

� Springer Science+Business Media B.V. 2010

Abstract Immunosenescence is characterized by a

series of changes of immune pathways, including a

chronic state of low-grade inflammation. Mounting

evidence from experimental and clinical studies sug-

gests that persistent inflammation increases the risk of

cancer and the progression of the disease. Cancer

vaccination, which came into view in the last years as

the most intriguing means of activating an immune

response capable of effectively hampering the pro-

gression of the preclinical stages of a tumour, has been

shown to be less effective in older age than in young

adults. Available evidence on the use of inhibitors of

inflammation has indicated their potential enhance-

ment of cancer vaccines, suggesting the possibility to

improve the low effectiveness of cancer vaccines in old

age employing pharmacological or natural com-

pounds-based anti-inflammatory intervention. This

review addresses the effects of age and inflammation

on cancer development and progression, and specu-

lates as to whether the modulation of inflammation

may influence the response to cancer immunization.

Keywords Inflammation � Aging �Cancer vaccines

Introduction

Emerging evidence clearly suggests that there is a

symbiotic relationship between aging, inflammation

and chronic diseases such as cancer. Chronic inflam-

mation as risk factor for most cancers is well

recognized and the immunosenescence and the low-

grade systemic inflammation which characterize the

elderly population have been related to the increased

incidence of cancer present in advanced age. In the

last years, cancer vaccination came into view as the

most intriguing means of activating an immune

response capable of effectively hampering the pro-

gression of the preclinical stages of a tumour. The

emerging role of immune-based approaches in treat-

ing cancer is further emphasised by the fact that

cancer vaccines which can be applied in both

prevention and therapy are potentially less toxic than

chemo- or radiotherapy and could be especially

suitable for older more frail cancer patients. Taking

into account the strict relationship existing between

inflammation and cancer, the modulation of inflam-

mation may be proposed as a tool to improve the

effectiveness of cancer vaccines, particularly in

advanced age, when a decreased ability to mount

protective immunity after immunization against can-

cer exists. Though several existing experimental data

seem to support this possibility, the real chance to

increase cancer vaccines effectiveness reducing

inflammation remains at present a question to be

defined.

M. Provinciali (&) � A. Barucca � M. Cardelli �F. Marchegiani � E. Pierpaoli

Advanced Technology Center for Aging Research,

Scientific Technological Area, INRCA-IRCCS,

Ancona, Italy

e-mail: m.provinciali@inrca.it

123

Biogerontology (2010) 11:615–626

DOI 10.1007/s10522-010-9280-9

Here, we discuss the effects of age and inflam-

mation on cancer development and progression, and

speculate as to whether the modulation of inflam-

mation may influence the response to cancer

immunization.

Immunization in aging

As a means of disease prevention and control,

vaccines have proved to be highly effective and a

financially viable solution. However, once applied in

the elderly, evidence exists that immunization pro-

cedures are less effective at older age than in young

adults (Provinciali 2009). The effectiveness of most

vaccinations against infectious diseases in the elderly

has been reported to be lower than in young adult

ages. Influenza virus vaccines have generally proved

limited in preventing morbidity and mortality among

the elderly because of the lower immunological

protection that they may confer on older adults

compared to younger persons. Also, the effectiveness

of the pneumococcal polysaccharide vaccine in

reducing the risk of pneumonia was found to be

deficient in the elderly. Many older people do not

have immunity to tetanus, against which vaccines

have been available for decades. Finally, the measure

of anti hepatitis virus and anti-HBs in elderly people

after a combined hepatitis A/B vaccination has

underlined the decreased response to vaccinations

with increasing age. In recent years, preclinical

experimental data, mainly performed in mice trans-

planted with parental tumours or in transgenic mice,

have shown that also the effectiveness of anticancer

vaccination is reduced at older age than in young-

adult age, mainly because of the age-related changes

in the immune response against tumour antigens,

implying that vaccines may not be very effective in

predominantly elderly cancer patients (Provinciali

et al. 2003; Gravekamp 2007). Immunosenescence,

which has been described as a remodelling of the

immune system which appears early on and pro-

gresses throughout a person’s life, may not only have

an impact on the incidence of cancer, but also on

the effectiveness of preventive and therapeutic

approaches based on immune system activation.

The low efficacy of cancer vaccines in old age may

be attributable to different mechanisms, which may

act at the different steps of the immunisation process,

and whose exact influence still remains unclear. Both

positive and negative regulators of the immunolog-

ical pathways leading to tumor prevention or regres-

sion appear to be altered in the elderly, with a higher

impact of negative regulators and a lower effect of

positive factors (Provinciali 2009). Many of these

age-related changes are linked to inflammation.

Inflammation and aging

Inflammation is a complex series of events, involving

many cell types (macrophages, neutrophils, mono-

cytes, dendritic and mast cells), and their main

molecular products, such as prostaglandins, cyto-

kines, nuclear factor-B (NF-jB), chemokines and

angiogenic factors (Ahmad et al. 2009). These

factors, which are produced very early in the response

to multiple stresses, are important in being involved

in both host defence and pathology. On one hand,

there is increasing evidence that for an immune

response to be effectively established, an inflamma-

tory response is needed to help the process along,

and, in particular, for the activation of the acquired

immune response. On the other hand, there is also

considerable literature showing that inflammation in

excess is detrimental, and that excessive production

and release of cytokines may lead directly to

pathology. In fact, although inflammation is a nec-

essary response to clear infections, to repair tissue

insults, and suppress tumor initiation/progression,

chronic inflammation is also clearly correlated with

increased risk of developing cancer. The duality of

inflammation in controlling and promoting tumor

development is an area that requires further delinea-

tion, and, in particular, studies are required to

understand whether inflammation become chronic

because an inflammatory stimulus persists or because

of dysregulation in the control mechanisms that

normally turn the process off, as, for example, the

loss or the reduction of anti-inflammatory signals.

Several studies have shown that a low-grade

systemic inflammation characterizes aging and that

inflammatory markers are significant predictors of

mortality in old humans (Kundu and Surh 2008).

Chronic inflammation has been correlated with many

diseases and most of them are age-related diseases.

In fact, it is widely accepted that many of the

most important age-associated diseases, such as

616 Biogerontology (2010) 11:615–626

123

cardiovascular diseases, atherosclerosis, Alzheimer’s

disease, arthrosis and arthritis, sarcopenia and diabe-

tes share a common inflammatory background. The

age-related increased levels of inflammatory media-

tors in the blood, are mainly represented by increased

concentrations of IL-6, tumor necrosis factor-a (TNF-

a), and various acute-phase proteins. Many studies

have focused on IL-6, suggesting that aging indepen-

dently of any particular disease is associated with

low-grade increases in the plasma levels of this

inflammatory mediator. Increases of IL-6 have been

associated with many age-related diseases such as

cardiovascular disease, arthritis, osteoporosis and

type-2 diabetes (Ahmad et al. 2009). The increase in

IL-6 levels may then be a reflection of an increased

inflammatory state caused by underlying disease even

in the apparently healthy elderly person. Besides IL-6,

the higher levels of TNF-a correlate with functional

status and decreased chance of long-life survival in

elderly. Moreover, dysregulation and, in particular,

overproduction of TNF-a has been implicated in a

variety of human diseases including sepsis, malaria,

autoimmune diseases such as multiple sclerosis,

rheumatoid arthritis, systemic lupus erythematosus,

and Crohn’s disease, as well as cancer. Higher levels

of TNF-a were also found in elderly with type II

diabetes mellitus compared to age-matched controls,

and elevated levels of both IL-6 and TNF-a were

found in subjects before the appearance of diabetes.

The well established increase with age of plasma

levels of pro-inflammatory cytokines appears to be

unexpectedly present either in persons who enjoyed

successful aging and those who suffered age-associ-

ated pathologies (Franceschi et al. 2007).

Inflammation and cancer

Epidemiologic and experimental evidence supports

the concept that chronic inflammation promotes the

development and progression of cancer (Hussain and

Harris 2007). There is a strong association between

chronic inflammatory conditions in a particular organ

and cancer specific to that organ. This association

involves a time factor, the longer the inflammation

persists, the higher the risk of associated carcinogen-

esis. The most thoroughly studied examples are the

relationships between chronic inflammatory bowel

disease and the increased risk of colorectal cancer,

chronic gastritis resulting from Helicobacter pylori

infection and gastric adenocarcinoma, and chronic

hepatitis and liver cancer.

Mediators of the inflammatory response, e.g.,

cytokines, free radicals, prostaglandins and growth

factors, can induce genetic and epigenetic changes,

causing alterations in critical pathways responsible for

maintaining the normal cellular homeostasis and

leading to the development and progression of cancer.

The effect of the various inflammatory mediators in

tumorigenesis is described in detail in specific reviews.

Various mechanisms are involved in the link between

inflammation and cancer initiation and progression

(Fig. 1): (1) induction of genomic instability. Inflam-

matory leukocytes (macrophages, granulocytes) gen-

erate reactive oxygen (ROS) and nitrogen (RNS)

species which, in turn, leads to DNA damage in the

surrounding epithelial cells. ROS and RNS can cause

extensive damage to essential cellular components

(e.g., DNA, proteins and lipids), which can directly or

indirectly contribute to malignant transformation.

Free-radical damage can be caused by the pro-inflam-

matory prostaglandin enzyme, cyclooxygenase 2

(COX-2), which leads to the production of highly

reactive peroxide intermediates at high levels in a local

tissue environment. The possible role of retrotranspo-

sons and their connection with inflammation and

cancer, is discussed below; (2) enhanced proliferative

signals mediated by cytokines released by inflamma-

tory cells may potentially increase the number of cells

at risk for mutations; (3) alterations in epigenetic

events and subsequent inappropriate gene expression

(see below); (4) activation of suppressor cell

Fig. 1 Schematic presentation of the different pathways

induced by inflammation and its relation to cancer develop-

ment and progression

Biogerontology (2010) 11:615–626 617

123

populations by inflammatory mediators, and in partic-

ular of myeloid-derived suppressor cells (MDSCs) and

regulatory T cells (Treg), which may contribute to

tumor immune escape blocking anti-tumor immunity.

MDSCs are a heterogeneous mixture of immature

myeloid cells that are potent inhibitors of antitumor

immunity. They mediate their effects by inhibiting

CD4? and CD8? T cell proliferation, by blocking

natural killer cell activation, by limiting dendritic cell

maturation, and by polarizing immunity towards a type

2 phenotype. Freshly isolated MDSCs (CD11b?GR-

1?) do not have the capacity to inhibit T cells and only

MDSCs isolated from an inflammatory environment

such as a tumor acquire this competence. The link

between inflammation and induction of MDSCs, which

limit antitumor immunity and thereby promote tumor

growth, was recently confirmed using experimental

approaches reducing or increasing inflammation (Bunt

et al. 2007). Treg cells, which represent a CD4? T cell

population characterised by the expression of the

forkhead/winged helix transcription factor (Foxp3),

play an important role in tumour-mediated immuno-

suppression. Tumor or macrophage-derived PGE2

production has been shown to provoke immunosup-

pression by inducing FoxP3 expression and Treg

function in naıve CD4?CD25- cells; the selective

COX-2 inhibition was reported to reverse tumor

immunosuppression by reducing intratumoral Treg

cells (Sharma et al. 2005a); (5) activation of tumor

angiogenesis. Many of proinflammatory mediators,

especially cytokines, chemokines and prostaglandins,

turn on the angiogenesis and tumor cell-stroma com-

munication; (6) protection of cancer stem cells by

inflammatory microenvironment. Inflammatory cyto-

kines in the tumor microenvironment may constitute a

preferential niche for the survival of cancer stem cells.

The biology of tumour stem cells has been shown to be

strictly affected by the pro-inflammatory milieu of the

tumour: recent evidence shows that inflammatory

cytokines, such as IL-6, play primary roles in the

pathogenesis of breast cancer by sustaining the

survival and proliferative capacity of tumour stem

cells. Another cytokine, which was very recently

discovered to play a crucial role in the survival of

cancer stem cells and, in particular, of stem cells from

colon carcinoma, is IL-4.

Tumours play an important role in mediating

antigen-specific immune evasion through several

mechanisms, some of which inducing inflammatory

mediators. Tumor cells produce various factors that

attract leukocytes, which in turn produce cytokines

and chemokines that stimulate further tumor cell

proliferation; the inflammatory tumor microenviron-

ment is characterized by the presence of host

leukocytes both in the stroma and around the tumor.

A developing neoplasm can contain diverse leukocyte

populations, including neutrophils, dendritic cells,

macrophages, eosinophils, mast cells and lympho-

cytes. These inflammatory cells secrete an array of

cytokines, interleukins, interferons and other soluble

mediators and further induce secretion of cytokines

by resident stromal cells. Both cytokines that promote

and suppress proliferation of the tumor cells are

produced in the tumor microenvironment and is the

imbalance between the effects of these two classes of

activity that results in tumor promotion. Basic

research, in turn, has shown that many of the cells

and soluble factors involved in inflammation, when

found in association with tumours, are more likely to

contribute to tumor growth, progression, and metas-

tasis than to elicit an effective host anti-tumor

response. An analysis of genes differentially

expressed in the mammary gland transcriptome

during the progression of mammary carcinogenesis

in BALB/c mice that are transgenic for the rat HER-

2/neu oncogene (BALB-neuT664 V-E mice) identi-

fied four genes that encode inflammatory cytokines

whose increased expression in the tumour microen-

vironment is naturally associated with mammary

cancer progression (Calogero et al. 2007).

A common characteristic mediated by tumor cell

microenvironment is the switch of the cytokine

milieu from Th1 to Th2, with production of suppres-

sive and inflammatory cytokines. The last, in turn,

favour the induction of tumor tolerance through

expansion of MDSCs.

Inflammation, cancer, and endogenous

retroelements

Retroelements (REs) are DNA sequences capable to

mobilize themselves via an RNA intermediate. While

retroviruses represent a small class of REs which

acquired the capacity to leave an organism and to be

horizontally transmitted to new hosts, the large major-

ity of REs are represented by endogen REs or

retrotransposons, which are vertically transmitted (by

618 Biogerontology (2010) 11:615–626

123

heredity). In the human genome endogenous REs are

present in million copies, mostly LINE-1 elements

(constituting 17% of the genome and coding for an

endonuclease and a reverse transcriptase), HERVs

(human endogenous retroviruses, constituting about

8% of the genome and coding for gag, pro, pol and env

proteins) and Alu elements (constituting about 11% of

the genome and not coding for proteins). The activation

of REs seems to be associated with inflammation and

with autoimmune diseases. Observations suggest that

in psoriatic tissue the reverse transcriptase produced by

endogenous REs is increased respect to normal skin

(Moles et al. 2007). In rheumatoid arthritis, viral load

of HERV-K endogenous retroviruses can be detected

in plasma samples from patients, with higher levels

observed for those with active disease. The association

between REs and inflammation can be explained in at

least two ways. The first is that REs can be induced by

inflammation. In fact, RNA transcription of REs is

known to be induced by a wide range of stresses

including oxidative stress (Teneng et al. 2007), hence

inflammation-induced oxidative stress could be poten-

tially able to trigger REs activation. On the other side,

there are evidences that the relation between inflam-

mation and REs can proceed in the opposite direction,

with the inflammation being induced by REs activa-

tion. In fact, it has been demonstrated that in rheuma-

toid arthritis the expression of ORF1 p40 protein

produced by endogenous LINE-1 REs induces a set of

intracellular kinases mediators of inflammation, and

that the envelope protein expressed by endogenous

retrovirus MSRV (Multiple sclerosis-associated retro-

viral element) has proinflammatory properties and is

involved in the immunopathological cascades associ-

ated with chronic inflammatory and/or neurodegener-

ative diseases such as multiple sclerosis, even if the

latter argument is still debated. Moreover, recent

observations revealed that the single-stranded DNA

molecules produced by reverse transcriptase coded by

endogenous REs are immunogenic. In fact, a specific

nuclease called Trex1 metabolizes single-stranded

reverse-transcribed DNA derived from endogenous

REs, and when its activity is impaired the intracellular

accumulation of reverse-transcribed DNA induces

autoimmunity by the interferon-stimulatory DNA

(ISD) response (Stetson et al. 2008). Based on such

evidences, it has been suggested that the increased

expression of human endogenous retroelements such

as LINE-1 can trigger an innate immune response,

inducing autoimmunity and inflammation (Crow

2010).

The association between endogenous REs and

cancer is sustained by a growing set of evidences.

Among the epigenetic deregulation events associated

with cancer there is an overall decrease in methylation,

which largely reflects a decrease in the methylation of

endogen REs. Hypomethylation of LINEs, Alus and

other REs has been observed in various cancers, and

occurs in early stages in colon cancers. REs expression

is enhanced in urothelial and renal carcinoma cells, in

human leukemia and human breast cancers. It has been

suggested that hypomethylation of REs enhances their

transcriptional activity and, in turn, their enhanced de

novo transposition may promote genomic instability,

and thus facilitate tumor progression. As a matter of

fact, insertional mutagenesis caused by de novo

retrotransposition represents a powerful mutational

mechanism and poses a serious threat to the host

genome: at least 51 isolated cases of human diseases

have been found associated with de novo genomic

insertions of REs, mainly in germline, and de novo

insertions as somatic events have been observed in the

APC gene in colon cancer and in the c-myc gene in

breast carcinoma. Recent findings suggest that drug-

mediated inhibition of REs is able to reduce cell growth

and to stimulate the differentiation of cancer cell lines,

confirming a possible role for REs in carcinogenesis.

The activation of retroelements can hence behave

as double edged sword: with a causal role both in

inflammation (by triggering innate immunity) and in

cancer (by generating somatic mutations and genetic

instability), but also in its turn induced and maintained

by inflammation and/or cancer, in a positive feed-back

that could re-enforce the pathogenetic link between the

two conditions. Finally, it should be noted that proteins

and single-stranded DNA molecules derived from

endogenous REs, with their immunogenic properties

and expressed at high levels in cancers, deserve

attention as possible new targets for cancer

immunotherapy.

Inflammation and DNA methylation

CpG island methylation (epigenetic regulation) is a

post-replicative phenomenon and is usually associ-

ated with repression of transcription and thus with the

gene silencing, either in normal and pathological

Biogerontology (2010) 11:615–626 619

123

conditions. CpG islands are normally protected from

DNA methylation, but in relation to cancer or aging,

they are aberrantly methylated (Issa 2000). Epige-

netic mechanisms play a central role in controlling

the expression of critical genes, such as those that can

promote or suppress the tumor. In fact, there was

evidence of two typical patterns of aberrant methyl-

ation in cancer: (a) reduction of methylated cytosines

in oncogenes resulting in hyper-activation of the

same, (b) excessive methylation of CpG islands in

promoter regions of tumor suppressor genes (i.e. p16,

hMLH1, BRCA1, MGMT, GSTP1, TIMP-3 and

DAPK-1) with consequent loss of their function.

Generally, human cancer cells exhibit global

DNA hypomethylation as well as region-specific

hypermethylation.

Recently, Valinluck et al. analyzing the halogena-

tion of nucleic acids (5-chlorocytosine and 5-bromo-

cytosine) as a form of DNA damage have seen that

these products are found specifically in areas of tissue

inflammation (Valinluck and Sowers 2007). They

have also seen that these halogenated cytosine

damage products, very similar to 5-methyl cytosine,

are involved in the changes of methylation status and

so they consider this process the link between

inflammation and cancer. In fact, this 5-halocytosine

residue in the site of inflammation leads to an

inappropriate de novo methylation, driving the cancer

development. Also, these residues are retained and

accumulated in the genome, being not recognized as

damaged bases by DNA repair glycosylases. In

summary, inflammation creates a signature of aber-

rant DNA methylation. The strong link between

inflammation and cancer is now recognized by the

scientific literature. An interesting observation is the

increase in the methylation status in subjects who

developed gastric cancer and were positive for

infection of Helicobacter pylori than those with

gastric cancer but H. pylori negative. A causal role

of infection in the aberrantly state of methylation is

proposed. Studying tumor cell lines of human multiple

myeloma it has been found that interleukin-6 (IL-6) is

the main responsible for the methylation status of

p53 gene, an important cell cycle control and tumor

suppressor gene (Hodge et al. 2005).

The discovery of drugs with DNA methyltransfer-

ase inhibitory activity (DNA methyltransferase inhib-

itor drugs) that could restore the expression of genes

previously silenced have kindled great hopes in the

treatment of a disease, often fatal, such as cancer.

Unfortunately, this initial enthusiasm was soon

dampened by the high toxicity and the side effects

that occur with the use of these types of drugs.

Epigenetic signalling has a crucial role not only in

cancer and inflammation but also in aging. In fact,

‘‘aging epigenetics’’ is an emerging discipline that

promises the definition of a DNA methylome and a

histone modification map that will help in the

definition of a ‘‘young’’ versus an ‘‘old’’ phenotype

(Fraga and Esteller 2007). Overall, in many aged

mammalian tissues a progressive loss of methylated

cytosines in the repetitive regions (defined as low

global DNA methylation levels) and the presence of

patched sites of 5-methylcytosines in the promoter

regions were observed. Probably, the loss of global

DNA methylation during aging is due to the

progressive inefficacy of DNA methyltransferase1

(DNMT1) which is accompanied by an overexpres-

sion of DNMT3b that entails the aberrant hyperme-

thylation of the regions such as promoter CpG

islands. Interestingly, aging and cancer share com-

mon mechanisms, i.e. global DNA hypomethylation,

aberrant promoter hypermethylation and modest

DNMT overexpression.

Inflammation, cancer and aging

In elderly population a low-grade increase in the

levels of circulating TNF-a, IL-6, soluble IL-2

receptors, CRP (C reactive protein) and cholesterol,

which act as inflammatory mediators has been

reported. Altered cytokine profiles due to aging of

the innate immune system and/or of non-immune cell

types, are hypothesised to contribute to age-related

changes in the structure and function of tissues,

pathophysiological changes, and the development of

chronic diseases of aging. Inflammatory cytokines

and other mediators of inflammation can also serve as

strong near-term predictors of mortality associated

with age-related chronic diseases. Chronic inflamma-

tion causes the release of a plethora of agents, such as

cytokines, prostaglandins, chemotactic factors, reac-

tive oxygen and nitrogen species. It also determines

changes in gene expression which favour the activa-

tion of oncogenes and down-regulation of tumour

suppression genes. These factors also change the

responses of cells to apoptosis signals and up-regulate

620 Biogerontology (2010) 11:615–626

123

angiogenesis factors as well as factors favouring the

growth of tumour cells. Moreover, some of the same

factors cause impairments in immune surveillance,

which facilitates the escape of tumour cells from

surveillance and their clonal expansion. Since the up-

regulation of the inflammatory response is a major

characteristic of the remodelling process of the

immune system during aging, the ‘‘aged’’ microen-

vironment may constitute a preferential niche for the

initiation and progression of cancer. Several exam-

ples may be provided by: (1) the local increase of

inflammatory cytokines proper of aging, such as IL-4

and IL6, may favour the survival of cancer stem cells;

(2) the immune suppression induced by tumour cell-

derived prostaglandins may have particular implica-

tions in aging, since lymphocytes from elderly

subjects are known to be more sensitive to inhibition

by prostaglandins in comparison with lymphocytes

from younger individuals; (3) the age-related increase

of inflammatory mediators may enhance the accu-

mulation of MDSCs and Treg which inhibit tumour

immunity and accelerate tumour progression thereby

supporting the hypothesis that the induction of

suppressor cells which down-regulate tumour immu-

nity is one of the mechanisms linking inflammation

and cancer; (4) the increased transcriptional activity

of retrotransposons may provide another biological

event that may connect inflammation to cancer in

aging. The importance of increased REs transcription

in cancer initiation/progression may be particularly

relevant in elderly subjects, since aging is character-

ized by a hypomethylation, and, consequently, an

increased expression of REs; (5) another character-

istic of aging, that may favour the persistence of an

inflammatory status and the development of cancer, is

represented by the lack or the low activation of anti-

inflammatory cytokines. An impaired anti-inflamma-

tory machinery may have detrimental consequences

for the success of immunological responses: the

reduced capability to counteract the chronic low-

grade inflammation may be not sufficient to antag-

onize inflammation-induced tumor protection and

tumor-mediated immune inhibition. A good example

of the role played by anti-inflammatory mechanisms

is offered by centenarians. Centenarians are unique in

that, despite high levels of pro-inflammatory markers,

they also exhibit anti-inflammatory markers that may

delay disease onset. In fact, although centenarians

are quite able of mounting effective inflammatory

responses, their inflammatory status is compensated

by the concomitant development of strong and

effective anti-inflammatory responses and by a higher

frequency of genetic markers associated with better

control of inflammation (Franceschi et al. 2007); (6)

indoleamine-2,3-dioxygenase (IDO) is an enzyme

which catalyses the initial and rate-limiting step in

the catabolism of tryptophan along the kynurenine

pathway and which may be upregulated by inflam-

matory cytokines causing immunosuppressive activ-

ity. IDO activity was found to increase with older age

and to predict mortality in nonagenarians, suggesting

that increased IDO activity might be a mechanism

involved in the decline of T cell responses in

immunosenescence.

One of the main questions that gerontologists have

to explain concerns the molecular causes involved in

the increased inflammation in the elderly, and, in

particular, whether they are mainly linked to genetic or

environmental causes. The profound alteration of the

immune system with aging, called immunosenescence,

is a phenomenon extensively demonstrated. The sus-

tained attrition on the immune system caused by

repeated antigen stimulations is likely responsible for

the chronic immune system activation and inflamma-

tion. In turn, the thymic involution and the consequent

loss of virgin T cells, lead the body more prone to a

variety of infections. In response to a persistent

inflammatory status, an accumulation of dysfunctional

lymphocytes and expanded clones of memory/effector

CD8? T cells occur and the subsequently filling up of

the ‘‘immunological space’’ increase the risk of

infectious, neoplastic and degenerative disorders. On

the whole, accumulation of memory and effector T

cells, decrease of naıve T cells and marked reduction of

T cell repertoire, mostly regarding CD8? T cells, have

been proposed as ‘‘hallmarks of immunosenescence’’

in humans (Franceschi et al. 1999). Besides the

shrinkage of immunological repertoire, some other

immunological responses decrease their efficiency.

Specifically, dendritic cells in the elderly are less

efficient in activating B and T lymphocytes, cd T cells

are decreased in number and function, B lymphocytes

decreased significantly with age and antibodies gener-

ated in the elderly are less protective than those of

young (De Martinis et al. 2005; Provinciali and

Smorlesi 2005). The innate immune system (NK cells,

macrophages, granulocytes) seems only moderately

affected by age, even though some alterations at the

Biogerontology (2010) 11:615–626 621

123

level of most of the components of the innate pathway

have been demonstrated. It is important to note that the

failure in the complex regulation of inflammatory

processes to resolve cellular damage sustained could

lead to malfunctioning of immune processes in aging

subjects. Also, according to ‘‘the remodelling theory of

aging’’ the immunosenescence results from the balance

between the continuous adaptation of the body to the

deteriorative changes occurring over time. Globally,

ancestral, innate immunity is preserved, while recent

clonotypical immunity deteriorates (Franceschi et al.

1995).

Recent data have suggested that the dysregulation

of proinflammatory cytokine production seems to be

mainly related to an intrinsic alteration present in

cells from aged individuals. Hematopoietic stem cells

from old animals have been shown to differentiate in

vivo in CD4? T cells producing IL-4 levels charac-

teristic of old age, even when these stem cells are

injected in a young host (Donnini et al. 2007). In

human, hematopoietic progenitors from old healthy

subjects differentiate in vitro in cells producing

higher concentrations of inflammatory cytokines than

those obtained in cultures from young donors in the

same experimental conditions. Thus, cells from aged

donors retain their capacity to produce higher levels

of inflammatory cytokines independently of the

microenvironment in which they proliferate and

differentiate.

Inflammation and effectiveness of cancer vaccines

Immunoprevention and immunotherapy for tumor-

associated antigens is now a major field of investi-

gation for the treatment of cancer. Many of the novel

immune-based therapies involve active immunization

and are likely to be most effective in immunocom-

petent tumor-bearing individuals who have minimal

alteration of immune homeostasis. For this reason,

elderly patients do not seem to represent good

candidates for immunization-based preventive or

therapeutic approaches. Given the causal relationship

between inflammation and the induction of cancer,

adjunctive therapies that reduce inflammation prior

to immunization, might significantly enhance the

efficacy of any active immunotherapy. Although the

link between inflammation and cancer has been

clearly demonstrated and various anti-inflammatory

substances have been reported to have anti cancer

effects, scarce and fragmentary evidence has been

provided until now on the possibility to potentiate

cancer vaccination switching off inflammation.

Inflammation is included among the stimuli capable

to induce COX-2, a COX isoform which catalyzes a

key step in arachidonic acid metabolism and produc-

tion of prostaglandins. Prostaglandins, in particular

PGE2, can enhance tumorigenesis. An elevated

expression of COX2 is frequently reported in a

variety of different human cancer and has been

localized in both tumor epithelial cells and stroma

supporting autonomous as well as landscaping effects

in tumor development. Epidemiological, animal and

human clinical studies have shown that nonsteroidal

anti inflammmatory drugs (NSAIDs) are chemopre-

ventive for colon adenoma and cancer. Drugs that

selectively inhibit the COX-2 enzyme, including

NSAIDs, are being studied to determine their impact

on local tumor biology and development, and in

clinical trials. Recent studies have suggested protec-

tive effects of COX-2 inhibitors in colorectal cancer

and breast cancer. It has been observed that people

regularly taking non-steroidal anti-inflammatory

drugs (NSAIDs) have lower risk of developing

cancer than people who don’t take the drugs. Several

small studies of colorectal, non-small cell lung

cancer, breast, cervical and esophageal tumours have

shown that increased COX-2 levels are associated

with poor clinical prognosis. Animal models for

colorectal cancer showed similar patterns of COX-2

expression and response to COX-2 inhibitors as

human neoplasias. Several recent studies have shown

that blockade of PGE2 produced by tumor cells and/

or tumor-associated leukocytes can limit a significant

portion of the immunosuppressive response and may

result in a potentiation of cancer vaccines. A COX-2

inhibitor enhanced antitumor immune responses

induced by the transcutaneous vaccination with

cytosine-phosphate-guanosine-oligodeoxynucleotides

(CpG-ODN) and ovalbumin. In this study either Th1-

type immune responses and generation of CTLs or

antigen-specific antitumor immunity in vivo were

induced (Inoue and Aramaki 2006). Therapeutic

administration of dendritic cells pulsed in vitro with

Hsp70 in the presence of a COX-2 inhibitor signif-

icantly reduced progression of B16 melanoma in

mice and enhanced survival through the induction of

IFN-c mediated protective immunity (Conroy et al.

622 Biogerontology (2010) 11:615–626

123

2008). In another experimental model, COX-2 inhi-

bition significantly increased the effect of a vaccina-

tion employing an adenoviral vector expressing the

E7 protein towards tumor cells expressing the same

antigen. This increased efficacy was associated with

the generation of a Th1-type tumor microenviron-

ment and a markedly increased number of tumor-

infiltrating specific CD8 T cells (Haas et al. 2006).

Similarly, the COX-2 inhibitor, SC-58236, increased

the effectiveness of a cancer vaccine using irradiated

tumor cells skewing towards a type 1 cytokine

response mainly mediated by IFN-c (Sharma et al.

2005b). In a more recent paper, conducted in a

different experimental model, it was demonstrated

that the combined vaccination with a mycobacterium

leprae protein and either a Toll-like receptor 4

(TLR4, EM005), TLR7 (Imiquimod), or TLR9

(CpG DNA) agonist, induces Th1-type responses

that limit local inflammation upon M. leprae infection

(Raman et al. 2009). The improving capacity of the

TLR7 agonist Imiquimod was already demonstrated

in a spontaneous mammary adenocarcinoma tumor

model (Smorlesi et al. 2005). In this study, imiqui-

mod was able to potentiate DNA vaccination using a

plasmid DNA encoding rat HER-2/neu in transgenic

mice. Spontaneous mammary tumours were delayed

and both antibody and cell-mediated immune respon-

siveness against HER-2/neu were increased.

Although there are not direct evidences in immu-

nization studies TNF-a antagonists represent good

candidates to potentiate the activity of cancer vac-

cines. TNF antagonists (etanercept, infliximab, ada-

limumab), which have been licensed for clinical trial in

the treatment of rheumatoid arthritis and Crohn’s

disease, have demonstrated to be endowed of various

actions which would be useful in a biological therapy

for cancer, namely, inhibition of cytokine/chemokine

production, reduced angiogenesis, prevention of leu-

cocyte infiltration, inhibition of matrix metallopro-

teases, and improvement of bone marrow function

(Sethi et al. 2009). Recently, we have observed in

psoriatic subjects treated with Etanercept for 24 weeks

an improvement in the insulin sensitivity, probably

through an inflammation pathway (Marra et al. 2007).

Several compounds that can inhibit TNF-a expression,

synthesis, and signaling are also available. These

include thalidomide, which is currently being used

for treatment of multiple myeloma, pentoxifylline,

and numerous products from fruits, vegetable and

traditional medicinal plants, and which can be tested in

experimental models of cancer vaccines. Among the

natural compounds that may impact on cancer immu-

nization are Vitamin E analogues. Vitamin E in nature

encompass a family of tocopherols and tocotrienols

which exert an immunoregulatory effect. The immu-

nomodulation of Vitamin E compounds is the result of

two mechanisms: (i) a direct effect on T cells, and (ii)

an indirect action through its anti-inflammatory prop-

erties, mainly related by the reduced production of

PGE2. In a recent study tocotrienols were shown to

exert better anti-inflammatory activity than alpha-

tocopherol by affecting IL-6 and nitric-oxide produc-

tion and reducing PGE2 release. Also in vivo tocotri-

enol supplementation has been shown to contribute to

immunoregulation, antibody production, and resis-

tance to implanted tumor. Like tocopherols, tocotrie-

nols are powerful antioxidant; they possess

neuroprotective and cholesterol lowering but also

proapoptotic properties not found in tocopherols.

Emerging in vitro and in vivo evidences have mani-

fested the anti-cancer activity of tocotrienols on

numerous human cancers. Very recently, d- and

c-tocotrienols were reported to exert a potent antican-

cer effect on breast cancer cell lines by inducing

apoptosis and transcriptional up-regulation of senes-

cent-like growth arrest markers (Pierpaoli et al. 2010).

The anticancer properties of tocotrienols were also

evaluated in a variety of animal models. These

preclinical studies have shown that tocotrienols inhibit

liver and lung carcinogenesis and suppress the growth

of breast tumor. The recent observation that a tocotri-

enol-rich fraction isolated from palm oil was able to

improve the efficacy of vaccines against breast cancer

in a mouse experimental model (Abdul Hafid et al.

2010) demonstrates the utility of certain nutritional

products or supplements to provide an immune mod-

ulation able to fight tumour and to improve the

outcome of treatment.

Silybin, the major flavonolignan from the extracts of

milk thistle of Silybum marianum, is an effective

antioxidant and anti-inflammatory compound with

antitumor-promoting activity that deserves particular

attention for its potential use as adjuvant of cancer

vaccines. Silybin was found to induce growth inhibi-

tion and apoptosis of a panel of human and murine

tumor cell lines as well as to exert anticancer effect in

an in vivo transgenic tumor model (Provinciali et al.

2007). Silybin was shown to induce strong anticancer

Biogerontology (2010) 11:615–626 623

123

effects by down-regulation of inflammatory and

angiogenic responses, involving HIF-1alpha, STAT3,

and NF-kB transcription factors, as well as COX-2 and

iNOS. In a number of in vitro human cell experimental

systems silymarin was found to suppress TNF-induced

activation of NF-kB 100 times better than aspirin. The

anti-inflammatory and anticancer effects of silybin

are related to the potent inhibition of NF-kB. This

transcription factor is linked with numerous genes

that regulate inflammation, immune function, stress

response, cell differentiation, apoptosis, and cell

survival, and is critically involved in the processes of

development and progression of cancer. Others non-

cytotoxic natural compounds have shown effective

anti-tumor/anti-inflammatory activity by repressing

NF-kB activity. Curcumins, the main biologically

active polyphenols of turmeric plant, are powerful in

vivo antioxidants. A large body of experimental works

supports the efficacy of curcumins as anti-inflamma-

tories. They have also shown chemo-preventive effects

in cellular and animal models. Curcumins seem to

exert their biological activity by strong inhibition of

NF-kB. A very recent in vitro/in vivo study showed the

synergic antitumor action of curcumin and resveratrol,

another polyphenol compound with anti-tumor/anti-

inflammatory activity (Provinciali et al. 2005), in colon

cancer models. They found that the inhibition of

tumours in response to curcumin and/or resveratrol

was associated with the reduction in proliferation and

stimulation of apoptosis accompanied by attenuation

of NF-kB activity, suggesting that the combination

of curcumin and resveratrol could be an effective

preventive/therapeutic strategy for colon cancer. In

other studies it has been shown that pharmacological

inhibitors of L-arginine catabolism may enhance

cancer immunotherapy. In tumor-bearing mice, the

combination of NCX-4016 (nitroaspirin), which tar-

gets multiple immunosuppressive pathways by inhib-

iting COX-1, COX-2, arginase and nitric-oxide

synthase and DNA-based vaccination increased the

number of tumor-specific CTLs and significantly

extended survival.

Concluding remarks

The chronic inflammation represents one of the

hallmarks of immunosenescence and its well estab-

lished link with cancer clearly suggests its direct

involvement in aging related cancer initiation and

progression. Even if it has been clearly demonstrated

that cancer vaccines are less effective in older age than

in young adult, the exact role of inflammation in the

success of cancer immunization, and in particular

whether inflammation may reduce the efficacy of

cancer vaccines, remains to be established. The

evidence available on the use of inhibitors of inflam-

mation, has suggested their potential enhancement of

cancer vaccines. Unfortunately, all studies that have

shown improved T cell responses using anti-inflam-

matory substances as adjuvant of cancer vaccination

were performed in young age and no data has been

reported until now in aging models. The age-related

changes occurring at the level of immunological

mediators require a careful examination of the mech-

anisms potentially involved in the success or in the

failure of anti-inflammatory approaches in old age.

One of the main reasons for the lower effectiveness of

cancer vaccines in old ages is the lack of naıve T cells

(Utsuyama et al. 1992), and the down-regulation of

inflammation-induced T cell responses by anti-inflam-

matory drugs might not improve T cell activation at

older age, since naıve T cells are almost completely

absent at this age. Perhaps, the adjuvant effect of anti-

inflammatory substances could be more likely directed

against suppressor cell populations, such as MDSCs or

Treg cells, that are upregulated by inflammation in old

ages, or angiogenesis, or could be effective in inducing

apoptosis of tumor cells, or preventing activation of RE

rather than improving T cell activation at older age.

Furthermore, since innate immune responses are less

affected at older age than adaptive T cell responses,

targeting natural killer cells or macrophages against

cancer by anti-inflammatory substances, might result

in a better effect than targeting T cell responses.

Greater insight into the mechanisms underlying

inflammation and its regulation, not only at a cellular,

but also at a molecular level, will be required for

planning tumour immunization procedures with

increased effectiveness, particularly for old subjects.

References

Abdul Hafid SR, Radhakrishnan AK, Nesaretnam K (2010)

Tocotrienols are good adjuvants for developing cancer

vaccines. BMC Cancer 10:5. doi:10.1186/1471-2407-

10-15

624 Biogerontology (2010) 11:615–626

123

Ahmad A, Banerjee S, Wang Z, Kong D, Majumdar APN,

Sarkar FH (2009) Aging and inflammation: etiological

culprits of cancer. Curr Aging Sci 2:174–186

Bunt SK, Yang L, Sinha P, Clements VK, Leips J, Ostrand-

Rosenberg S (2007) Reduced inflammation in the tumor

microenvironment delays the accumulation of myeloid-

derived suppressor cells and limits tumor progression.

Cancer Res 67:10019–10026

Calogero RA, Cordero F, Forni G, Cavallo F (2007) Inflam-

matory component of mammary carcinogenesis in ErbB2

transgenic mice. Breast Cancer Res 9:211–220

Conroy TD, Jamicki AG, Higgins SC, Sutton C, Mills KH

(2008) Therapeutic vaccination with dendritic cells pulsed

with tumor-derived Hsp70 and a COX-2 inhibitor induces

protective immunity against B16 melanoma. Vaccine

26:3540–3549

Crow MK (2010) Long interspersed nuclear elements (LINE-

1): potential triggers of systemic autoimmune disease.

Autoimmunity 43:7–16

De Martinis M, Franceschi C, Monti D, Ginaldi L (2005) In-

flamm-ageing and lifelong antigenic load as major deter-

minants of ageing rate and longevity. FEBS Lett

579:2035–2039

Donnini A, Re F, Orlando F, Provinciali M (2007) Intrinsic and

microenvironmental defects are involved in the age-rela-

ted changes of Lin-c-kit? hematopoietic progenitor cells.

Rejuvenation Res 10:459–472

Fraga MF, Esteller M (2007) Epigenetics and aging: the targets

and the marks. Trends Genet 23:413–418

Franceschi C, Monti D, Barbieri D, Grassilli E, Troiano L,

Salvioli S, Negro P, Capri M, Guido M, Azzi R et al

(1995) Immunosenescence in humans: deterioration or

remodelling? Int Rev Immunol 12:57–74

Franceschi C, Valensin S, Fagnoni F, Barbi C, Bonafe M

(1999) Biomarkers of immunosenescence within an evo-

lutionary perspective: the challenge of heterogeneity and

the role of antigenic load. Exp Gerontol 34:911–921

Franceschi C, Capri M, Monti D, Giunta S, Olivieri F, Sevini F,

Panourgia MP, Invidia L, Celani L, Scurti M, Cevenini E,

Castellani GC, Salvioli S (2007) Inflammaging and anti-

inflammaging: a systemic perspective on aging and lon-

gevity emerged from studies in humans. Mech Ageing

Dev 128:92–105

Gravekamp C (2007) Cancer vaccines in old age. Exp Gerontol

42:441–450

Haas AR, Sun J, Vachani A, Wallace AF, Silverberg M, Ka-

poor V, Albelda SM (2006) Cycloxygenae-2 inhibition

augments the efficacy of a cancer vaccine. Clin Cancer

Res 12:214–222

Hodge DR, Peng B, Cherry JC, Hurt EM, Fox SD, Kelley JA,

Munroe DJ, Farrar WL (2005) Interleukin 6 supports the

maintenance of p53 tumor suppressor gene promoter

methylation. Cancer Res 65:4673–4682

Hussain SP, Harris CC (2007) Inflammation and cancer: an

ancient link with novel potentials. Int J Cancer 121:2373–

2380

Inoue J, Aramaki Y (2006) Cyclooxygenase-2 inhibition pro-

motes enhancement of antitumor responses by trascuta-

neous vaccination with Cytosine-phospate-guanosine-

oligodeoxynucleotides and model tumor antigen. J Invest

Dermatol 127:614–621

Issa JP (2000) CpG-island methylation in aging, cancer. Curr

Top Microbiol Immunol 249:101–118

Kundu JK, Surh Y-J (2008) Inflammation: gearing the journey

to cancer. Mutat Res 659:15–30

Marra M, Campanati A, Testa R, Sirolla C, Bonfigli AR,

Franceschi C, Marchegiani F, Offidani A (2007) Effect of

etanercept on insulin sensitivity in nine patients with

psoriasis. Int J Immunopathol Pharmacol 20:731–736

Moles JP, Tesniere A, Guilhou JJ (2007) Reverse transcriptase

activity in human normal and psoriatic skin samples. Br J

Dermatol 157:482–486

Pierpaoli E, Viola V, Pilolli F, Piroddi M, Galli F, Provinciali

M (2010) c- and d-tocotrienols exert a more potent anti-

cancer effect than a-tocopheryl succinate on breast cancer

cells irrespective of HER-2/neu expression. Life Sci

86:668–675

Provinciali M (2009) Immunosenescence and cancer vaccines.

Cancer Immunol Immunother 58:1959–1968

Provinciali M, Smorlesi A (2005) Immunoprevention and

immunotherapy of cancer in aging. Cancer Immunol Im-

munother 54:93–106

Provinciali M, Smorlesi A, Donnini A, Bartozzi B, Amici A

(2003) Low effectiveness of DNA vaccination against

HER-2/neu in ageing. Vaccine 21:843–848

Provinciali M, Re F, Donnini A, Orlando F, Bartozzi B, Di

Stasio G, Smorlesi A (2005) Effect of resveratrol on the

development of spontaneous mammary tumors in HER-2/

neu transgenic mice. Int J Cancer 115:36–45

Provinciali M, Papalini F, Orlando F, Pierpaoli S, Donnini A,

Morazzoni P, Riva A, Smorlesi A (2007) Effect of the

silybin-phosphatidylcholine complex (IdB1016) on the

development of mammary tumours in HER-2/neu trans-

genic mice. Cancer Res 67:2022–2029

Raman VS, O’Donnell J, Remy BH, Goto W, Lahiri R, Gillis

TP, Reed SG, Duthie MS (2009) Vaccination with the

ML0276 antigen reduces local inflammation but not

bacterial burden during experimental mycobacterium

leprae infection. Infect Immun 77:5623–5630

Sethi G, Sung B, Kunnumakkara AB, Aggarwal BB (2009)

Targeting TNF for treatment of cancer and autoimmunity.

Adv Exp Med Biol 647:37–51

Sharma S, Yang SC, Zhu L, Reckamp K, Gardner B, Baratelli

F, Huang M, Batra RK, Dubinett SM (2005a) Tumor

cyclooxygenase-2/prostaglandin E2-dependent promotion

of FOXP3 expression and CD4 ? CD25 ? T regulatory

cell activities in lung cancer. Cancer Res 65:5211–5220

Sharma S, Zhu L, Yang SC, Zhang L, Lin J, Hillinger S,

Gardner B, Reckamp K, Strieter RM, Huang M, Batra

RK, Dubinett SM (2005b) Cyclooxygenase 2 inhibition

promotes IFN-gamma-dependent enhancement of antitu-

mor responses. J Immunol 175:813–819

Smorlesi A, Papalini F, Orlando F, Donnini A, Re F, Provin-

ciali M (2005) Imiquimod and S-27609 as adjuvants of

DNA vaccination in a transgenic murine model of HER2/

neu-positive mammary carcinoma. Gene Ther 12:1324–

1332

Stetson DB, Ko JS, Heidmann T, Medzhitov R (2008) Trex1

prevents cell-intrinsic initiation of autoimmunity. Cell

134:587–598

Teneng I, Stribinskis V, Ramos KS (2007) Context-specific

regulation of LINE-1. Genes Cells 12:1101–1110

Biogerontology (2010) 11:615–626 625

123

Utsuyama M, Hirokawa K, Kurashima C, Fukayama M, In-

amatsu T, Suzuki K, Hashimoto W, Sato K (1992) Dif-

ferential age-change in the numbers of CD4?CD45RA?

and CD4?CD29? T cell subsets in human peripheral

blood. Mech Ageing Dev 63:57–68

Valinluck V, Sowers LC (2007) Inflammation-mediated cyto-

sine damage: a mechanistic link between inflammation

and the epigenetic alterations in human cancers. Cancer

Res 67:5583–5586

626 Biogerontology (2010) 11:615–626

123