The disastrous consequences of chronic inflammation

Definition:

Chronic inflammation is the prolonged response of inflammatory cells to microbial products and toxic insults. Macrophages are the predominant cells in chronic inflammation.

The causes of chronic inflammation include: Unregulated immune reactions as in allergy, & rheumatoid arthritis; stubborn infections resulting in granuloma formation; continuous exposure to toxic substances as in coal and lipid.

Macrophages, lymphocytes, and plasma cells all participate in the chronic inflammatory processes. Special population of macrophages are involved in inflammation and repair of damaged tissues. Macrophages and endothelium are able to secrete growth factors (VEGF & FGF) and lysosomal enzymes during inflammation.

Hallmark of chronic inflammation:

The hallmark of chronic inflammation include: Mononuclear cell infiltration, mainly macrophages; tissue destruction & tissue repair. Macrophage secretes IL-12 which stimulates T lymphocytes. This way, macrophage presents antigen to T lymphocytes that also propagate inflammation by recruiting more macrophages. T-lymphocytes secretes IF-gamma to recruit macrophages, & secretes IL-2 to recruit other T-lymphocytes.

Interstitial macrophages are able to also recruit plasma cells to sites of persistent inflammatory agents. The relationship between eosinophils and mast cells mediated by IgE, sets the stage for immune reaction. This reaction may result in life-threatening anaphylactic reaction or chronic inflammation.

Chronic inflammation can result in the formation of granulomas during a stubborn infection. Granuloma is the aggregation of epithelium-like macrophages surrounded by plasma cells and T lymphocytes. Seen in conditions like sarcoidosis, tuberculosis, and rheumatoid arthritis. These macrophages fuse together to form giant cells with combined many nuclei within the granuloma.

In conclusion, some systemic changes called “acute phase response” are seen in acute inflammation. The acute phase response in acute inflammation include: Fever; leukocytosis & neutrophilia in bacterial infections; eosinophilia in parasitic infections; lymphocytosis in viral infections; increased C-reactive protein & erythrocyte sedimentary rate. Other include: shivering, chills, anorexia, malaise, drowsiness.