Chronic Inflammation : Causes, Morphologic features, Mediators, Examples, & Clinical manifestations

Summary

Chronic inflammation is a prolonged immune response that causes ongoing tissue damage and attempts at repair, often leading to fibrosis. It can result from persistent infections, immune reactions, or unresolved acute inflammation. Key features include tissue destruction, fibrosis, and the formation of ulcers, abscesses, and strictures. The macrophage plays a central role in sustaining inflammation by secreting destructive agents and growth factors. Clinically, chronic inflammation can cause symptoms like organ distortion, ulceration, and systemic effects such as fever, weight loss, and anemia. Effective management is crucial to prevent further complications in various diseases.

Takeaways

• 😀 Chronic inflammation is a prolonged immune response that aims to remove foreign invaders and repair damaged tissues.
• 😀 Unlike acute inflammation, chronic inflammation lasts for a long period and is characterized by ongoing tissue destruction and attempts at repair by fibrosis.
• 😀 Chronic inflammation can arise from persistent infections, such as tuberculosis, leprosy, and syphilis, or from indigestible materials like calcium deposits and asbestos.
• 😀 Autoimmune diseases like rheumatoid arthritis and lupus, as well as organ transplant rejections, can also trigger chronic inflammation.
• 😀 Repeated episodes of acute inflammation, such as recurrent pancreatitis or cholecystitis, may evolve into chronic inflammation over time.
• 😀 Macroscopic features of chronic inflammation include ulcers, cavitatory lesions, abscesses, sinuses, and fistulas, often leading to functional impairment of affected organs.
• 😀 Microscopic features include infiltration by mononuclear cells (macrophages, lymphocytes), tissue necrosis, and fibrosis, with multinucleated giant cells in granulomatous inflammation.
• 😀 Macrophages play a central role in chronic inflammation, recruited from blood monocytes, proliferating at the site, and activated to secrete destructive agents and growth factors for repair.
• 😀 Chronic inflammation can result in fibrosis, thickening of organ walls, narrowing of lumens (strictures), and even distortion of organs like the liver or stomach.
• 😀 Systemic manifestations of chronic inflammation may include splenomegaly, hepatomegaly, anemia, weight loss, and low-grade fever, often due to the release of inflammatory cytokines.

Q & A

What are the two main types of inflammation discussed in the video?

The two main types of inflammation discussed are acute inflammation and chronic inflammation.

What is the key difference between acute and chronic inflammation?

Acute inflammation is a short-term response that occurs immediately after tissue injury, while chronic inflammation lasts for a prolonged duration and involves ongoing tissue destruction and repair processes.

What are some common causes of chronic inflammation?

Common causes of chronic inflammation include persistent infections (e.g., tuberculosis, leprosy, syphilis), persistent indigestible material (e.g., necrotic tissue, silica), immune-mediated reactions (e.g., autoimmune diseases, organ transplant rejection), and repeated episodes of acute inflammation (e.g., chronic pancreatitis).

How does chronic inflammation lead to tissue destruction?

Chronic inflammation causes ongoing tissue destruction through the continuous presence of inflammatory mediators, such as macrophages and other immune cells, that break down the affected tissue over time.

What are some common morphological features of chronic inflammation?

Macroscopic features include ulceration, cavitatory lesions (e.g., in pulmonary tuberculosis), abscess formation, and fibrosis, while microscopic features include mononuclear cell infiltration (mainly macrophages and lymphocytes), tissue necrosis, and granulation tissue formation.

What role do macrophages play in chronic inflammation?

Macrophages accumulate at the site of chronic inflammation through recruitment from the blood, proliferation, and immobilization. They are activated by cytokines such as interferon-gamma and perform functions like phagocytosis, secretion of destructive agents, and promoting tissue repair.

What is granulomatous inflammation, and when does it occur?

Granulomatous inflammation is a special type of chronic inflammation characterized by the formation of granulomas, which are clusters of macrophages, often seen in diseases like tuberculosis. It is a result of a strong immune response to persistent pathogens or foreign material.

What are some clinical manifestations of chronic inflammation?

Clinical manifestations of chronic inflammation include ulceration, sinus and fistula formation, cavitatory lesions, stricture formation, organ distortion, and fibrous adhesion formation. In some cases, these can lead to complications like hydrocephalus or constrictive pericarditis.

What is the significance of fibrosis in chronic inflammation?

Fibrosis occurs when tissue damage is repaired by the formation of scar tissue. This can lead to thickening of organ walls, narrowing of lumens (e.g., strictures), distortion of organs, and functional impairment, as seen in conditions like cirrhosis or gallstone disease.

How can chronic inflammation contribute to systemic manifestations?

Systemic manifestations of chronic inflammation include splenomegaly, hepatomegaly, lymphadenopathy, anemia of chronic disease, high ESR, low-grade fever, weight loss, and loss of appetite, all due to the prolonged release of cytokines and acute-phase reactants.