ImpactImpact

ofof

RaltegravirRaltegravir

onon

ImmuneImmune ReconstitutionReconstitution

andand

ThymopoiesisThymopoiesis

in in

HIVHIV--1 1 InfectedInfected

PatientsPatients

withwith UndetectableUndetectable

ViremiaViremia

Carolina Garrido, N Rallón, N Zahonero, M López, V Soriano, C de Mendoza, and JM Benito

Hospital Carlos III, Madrid

HIV HIV infectioninfection

andand

CD4 CD4 recoveryrecovery

HIV-infection CD4+T-cells Immune deficiency

Opportunistic infections

HAART HIV Viral Load CD4+T-cells

Raltegravir First-in-class integrase inhibitor Has proven potent antiviral activity but also showed good immunologic recovery

Background

RaltegravirRaltegravir

immunologicimmunologic

outcomesoutcomesBackground

THPE0132

700

600

500

400

300

CD

4 co

unt(

cell/

mm

3 )

ATV DRV RALn

baseline+ 6 monthsΔ

CD4

p

CD4+T cells

(cell/mm3)

52524 [344,703]444 [354,606]-22 [-127,55]

0.173

25231 [157-493]291 [176,492]

28 [-36,80]

0.104

86555 [429-776]630 [472,812]40 [-31,136]

0.012

Switching experiences in HCIII:

- ATV

- DRV

- RAL

Switch one drug for another in a context

of undetectable viremia

ImmunologicImmunologic

recoveryrecoveryBackground

The CD4+T-cellrecovery after HAART can be due to:

Recent thymicemigrants (RTEs)

The expansion ofperipheral T cells

Thymus Supply of new lymphocytes to the periphery. Impaired during HIV-infection

Kohler and Thiel, Blood, 2009

ThymicThymic

functionfunction

Thymic function T-cell receptor excision circles (TRECs) Stable DNA episomes

formed during T-cell receptor gene rearrangement within the thymus↑

% cells TREC+ = RTEs

↓

% cells TREC+ = cells after several divisionsTRECs

are lost

upon

cell

division

Background

CD31

Surface marker

Present in TREC-rich T-cells

Indicator of recent thymic emigrants

ObjectiveObjective

The aim of the study was

to characterize the immunologic recovery of

HIV-infected patients under suppressed viremia

after switching to a RAL containig regimen

PatientsPatients

andand

samplessamples

Viral load < 50 RNA cop/mL

Baseline +6 months

Switch to a RAL-containig regimenMantain the same regimen

Control group Raltegravir

group

For each patient, two blood samples were collected: one at baseline

one 6 months later

PBMCs were obtained from peripheral blood by density gradient centrifugation

Cells were criopreserved until use

Methods

ImmunologicImmunologic

characterizationcharacterization

CD4+T-Lymphocyte

effector naiveeffector memory

central memory

- CD4-PC7

- CD45RA-ECD

- CD27-PE

- CD38-PC5

- CD31-FITC

PBMCs were stained with fluorescent-conjugated monoclonal antibodies specificfor cell surface markers:

Expression of these surface markers was analyzed by flow cytometry using a 5-color-flow-cytometer FC500 (Coulter, Miami, FL)

Activation markerRecent thymic emigrants (RTE) marker

Maturation markers

Methods

StudyStudy

populationpopulation

Baseline characteristics of the study population did not differ among groups

Control group: 84% PI (67% ATV, 17% LPV); 11% NNRTIs; 5% NRTIs

RAL group: 53% PI; 47% 2NRTIs

Results

CD4CD4++TT--cellcell

countcount

After the 6-month period, only the group whoswitched to RAL experienced a significantchange in CD4 count

Control

800

600

400

200

0

Raltegravir

CD

4+ T-c

ell(

cell/

mm

3 )

*

Results

CD4CD4++TT--cellcell

maturationmaturation

Effector

Naive

Effector

memory

Central memory

Effector

Naive

Effector

memory

Central memory

0.421

0.014

0.005

0.421

0.117

0.199

0.723

0.133

*

*

Wilcoxon Signed Ranks Testp

After the 6-months period, significant changes in the population subsets distribution only occurred in the RAL group, where the subset of naive cells increased its proportion

+6 monthsBaseline

Con

trol

Ral

tegr

avir

Results

CD31 CD31 expressionexpression

CD31 expression did not vary significantly in any of the study groups neither in the whole population or in particular cellular subsets

Results

Baseline

+ 6 months

p=0.811

p=0.306 p=0.191

p=0.420

p=0.679 p=0.277p=0.306

p=0.872

p=0.314

p=0.117

CD38 CD38 expressionexpression

In the control group there was a slightlysignificant decrease in the CD38 expressionlevel of both naive and effector subsets

In the RAL group, we observed a significantdecrease in the effector population but a significantincrease in the level of CD38 expression of naive cells

Results

* * * *

p=0.036

+ 6 monthsBaseline

AssociationAssociation

betweenbetween

CD38 CD38 andand

CD31CD31Results

100806040200

% naïve cells expressing CD31

100

80

60

40

20

0

% n

aïve

cel

ls e

xpre

ssin

g C

D38

R Sq Linear = 0,51

Control-RAL + 6 months

Pearson correlation sig (2-tailed) < 0.001

100806040200

100

80

60

40

20

0

R Sq Linear = 0,262

% naïve cells expressing CD31

% n

aïve

cel

ls e

xpre

ssin

g C

D38

Control-RAL baseline

Pearson correlation sig (2-tailed) = 0.001

ConclusionsConclusions

Switching to a RAL-containing regimen in a context of suppressed viremia induced a significant gain in CD4+T-cell count.

This improvement was mainly due to an increase in the subset of CD4+Naive cells.

The increase in CD4+naive cells could not be clearly associated to recent thymicemigrants, as there was no significant rise in the expression of CD31.

However, the increase of CD38 expression on naive CD4+T-cells and thesignificant association between CD38 and CD31 markers on this subset of CD4+ cells, suggest that the immune recovery observed in patients switching to RAL may be due, at least in part, to newly produced cells in the thymus.

AcknowledgmentsAcknowledgmentsInfectious

Diseases

Department

of

Hospital Carlos III

(Molecular Biology Lab. + Clinical Section)

Norma Rallón

Mariola López

Jose Miguel Benito

Natalia Zahonero

Carmen de Mendoza

Vicente Soriano