SUMMARY

Inflammation represents a potent two-edge sword which has the capability to both protect as well as destroy the host. As a protection, inflammation provides an extremely effective mechanism to control the spread of microbial agents, as well as to repair trauma. Conversely, the inflammatory process can focus the same extremely potent tissues, but organisms themselves. A prime example of the latter is the tissue destruction associated with autoimmune disease.

The classic signs of inflammation namely, heat, redness, swelling and pain, and the associated loss of function, generally represent a complex group of vascular, neurologic and cellular responses to trauma. Histologically, inflammation can be characterized as the movement of inflammatory cells (polymorphonuclear leukocytes, monocytes and lymphocytes) as well as fluid (edema) from the vasculature into the tissue. The purpose of the movement of these cells and fluids into the tissue is multifold. The movement of fluids plays an important role in diluting toxic factors generated at sites of trauma and infection, as well as allowing influx of important serum protein such as the complement system, immunoglobulins and fibrinogen which are critical in fighting infection. Additionally, the movement of white blood cells, particularly polymorphonuclear leukocytes and monocytes-macrophages also play a central role: (1) both the destruction of microbial agents, as well; and (2) the removal of debris that is a result of the trauma. In fact, the removal of microorganisms and tissue debris by the inflammatory process represent a key step in the ultimate healing process by allowing repair to proceed in the form of granulation tissue. Granulation tissue, which is composed of leukocytes, as well as proliferating fibroblasts and endothelial cells, ultimately leads to the repair of the tissue via the generation of new blood vessels, proliferation of tissue cells and the formation of collagen.

INFLAMMATION OUTLINE

I. Definition of Inflammation (Acute vs. Chronic)

II. Hallmarks of Inflammation

III. Who are the Players?

A. Vessels/endothelium

B. Platelets

C. Red blood cells

D. Monocytes

E. PMNs

F. Lymphocytes

G. Plasma factors

H. Tissue cells/factors

IV. Major Events in Inflammation

A. Changes in blood flow

B. Movement of fluids (vasopermeability)

C. White blood cell events

D. Outcome (repair, regeneration and fibrosis)

V. Mediators and Mechanisms of Inflammation

A. Vasoactive factors

B. Leukoactive factors