Inflammation & Repair

Chronic Inflammation

Chronic Inflammation

Cell Types in Chronic Inflammation

• Macrophages• Types of Macrophages (fixed)

– Kupffer cells - liver– Pulmonary alveolar macrophages– Histiocytes - connective tissue– Microglia - brain– Osteoclasts - bone– Spleen/lymph nodes– Langerhans cells - epidermis

Other Cell Types

• Lymphocytes• Plasma cells• Eosinophils

– IgE mediated, parasitic infections• Mast Cells

Granulomatous Inflammation

• Granulomatous inflammation– focal accumulations of activated macrophages

with an epithelial-like (epithelioid) appearance. • Granuloma

– microscopic aggregation of epitheliod macrophages surrounded by a collar of lymphocytes and occasionally plasma cells.

Granulomatous Inflammation - TB

Granulomatous Inflammation - TB

Granulomatous Inflammation - TB

Granulomatous Inflammation - TB

Granulomatous Inflammation - TB

Healing and Repair

Cell Types with Different Regenerative Capacities

Resolution vs Repair

Granulation Tissue

• Proliferation of new blood vessels and fibroblasts

• Fibroblasts myofibroblasts

Granulation Tissue

Granulation Tissue

Wound Healing

• Primary union (healing by 1st intention) – healing of a clean surgical incision– very little tissue damage is present

• Secondary union (healing by 2nd intention)– healing of a large tissue defect

Healing by First Intention Healing by Second Intention

24 Hours

Healing by First Intention Healing by Second Intention

3 to 7 Days

Healing by First Intention Healing by Second Intention

Weeks

Aberrations of Wound Healing

• Inadequate granulation tissue/healing• Excessive repair

– Hypertrophic scar– Keloid

• Contractures

Hypertrophic Scar

Keloid

Conditions Inhibiting/Delaying Wound Healing

• Poor local vascular supply– Poor oxygenation, decreased bacterial

resistance, low temperature, and an acid pH• Deficiencies of vitamin C, protein, zinc• Infection• Tissue necrosis

– Foreign material delay healing and acts as a nidus for bacterial infection

• Excessive movement

Extracellular Matrix- Collagen -

• Tropocollagen is the basic unit• Intracellular

– procollagen• Extracellular

– procollagen cleavage & lysine oxidation cross-linking

– tensile strength

Wound Healing

• Replacement of Type III collagen by Type I in wound healing will have a maximal tensile strength of 70-80% of normal (takes about 3 months)

Outcomes of Acute Inflammation

The End

Chronic Inflammation&

Repair