Chronic inflammation - B. Pharma 2nd Semester Pathophysiology notes pdf

Chronic inflammation

Contents

•       Chronic inflammation

•       Granulomatous inflammation 

Objectives  

At the end of this PDF, student will be able to

•         Define ‘chronic inflammation’

•         Explain the causes of chronic inflammation

•         Describe the general features of chronic inflammation

•         Describe the pathogenesis granulomatous inflammation

Chronic inflammation

Chronic inflammation is defined as prolonged process in which tissue destruction and inflammation occur at the same time

Chronic inflammation – Causes

1.  Chronic inflammation following acute inflammation:

•       Prolonged acute inflammation

•       Tissue destruction is extensive

•       The bacteria survive & persist in small numbers at the site of acute inflammation

e.g. Osteomyelitis, pneumonia terminating in lung abscess

2. Recurrent attacks of acute inflammation:

•       Repeated attacks of acute inflammation

•       Culminate in chronicity of the process

e.g. - Recurrent urinary tract infection leading to chronic pyelonephritis

–      Repeated acute infection of gallbladder leading to chronic cholecystitis

3. Chronic inflammation starting de novo: 

•       Infection with organisms of low pathogenicity is chronic

     e.g. infection with Mycobacterium tuberculosis.

General features of chronic inflammation

Mononuclear cell infiltration

Infiltration of chronic inflammatory lesions

•       Phagocytes - circulating monocytes, tissue macrophages, epithelioid cells, multinucleated giant cells

•        Lymphoid cells

•       Chemotactic factors and adhesion molecules for continued   infiltration of macrophages

•       Local proliferation of macrophages

•       Longer survival of macrophages at the site of inflammation

  Tissue destruction or necrosis

•       Brought about by activated macrophages

•       Release a variety of biologically active substances

E.g. protease, elastase, collagenase, lipase, reactive oxygen radicals, cytokines (IL-1, IL-8, TNF-α), nitric oxide, angiogenesis growth factor

Proliferative changes

•       Result of necrosis

•       Proliferation of small blood vessels and fibroblasts is

•       Formation of inflammatory granulation tissue

•       Healing by fibrosis and collagen laying

Systemic effects of chronic inflammation

•       Fever:  mild fever, often with loss of weight and weakness

•       Anaemia

•       Leucocytosis

•       ESR:  elevated in all cases

•       Amyloidosis: Long-term cases of chronic suppurative Inflammation - secondary systemic (AA) amyloidosis

Types of chronic inflammation

Non-specific

•       Irritant substance - nonspecific chronic inflammatory

•       Formation of granulation tissue

•       Healing by fibrosis (chronic osteomyelitis, chronic ulcer)

Specific

Injurious agent causes a characteristic histologic tissue response

e.g. tuberculosis, leprosy, syphilis

Granulomatous inflammation

Granuloma

•       A tiny lesion about 1 mm in diamter

•       Comprises of epitheloid cells in the centre & lymphoid in the periphery 

•       Contains gaint cells

•       Associated with necrosis & fibrosis

•       Proliferation of fibroblast in the periphery

•       Due to presence of micro organism

e.g. Mycobacterium tuberculosis

–      Poorly digestible

–      Cell mediated immune response

Pathogenesis of granulomatous inflammation

•       Type IV hypersensitivity reaction

•       Engulfment by macrophages

•       Presentation of microbes to CD4+ T cells

•       Activation of T-cells

•       Cytokines

Composition of Granuloma

•       Epithelioid cells

•       Multinucleate giant cells

•       Lymphoid cells

•       Necrosis

•       Fibrosis

Summary

•       Chronic inflammation is defined as prolonged process in which tissue destruction and inflammation occur at the same time

•       Chronic inflammation may occur due to prolonged and recurrent attack of acute inflammation or may start de novo

•        Chronic inflammation is characterized by mononuclear cell infiltration, proliferation and necrosis

•       Granulomatous inflammation occur by proliferation of fibroblast in the periphery due to presence of micro organism