Inflammation & Repair

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

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

Wound Healing Primary union (healing by 1 st intention) –healing of a clean surgical incision –very little tissue damage is present Secondary union (healing by 2 nd intention) –healing of a large tissue defect

Healing by First IntentionHealing by Second Intention 24 Hours

Healing by First IntentionHealing by Second Intention 3 to 7 Days

Healing by First IntentionHealing 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