General pathology · Inflammation
Chronic inflammation: causes, cells and features !
- Process
Chronic inflammation lasts weeks to years: injury, the immune reaction and attempts at repair go on at the same time, often ending in scarring.
Updated 2026-11-01
What it is
Chronic inflammation is inflammation of long duration in which tissue destruction, inflammation and repair happen together. It follows acute inflammation that does not resolve or starts silently, driven by persistent microbes, autoimmunity, allergy or long exposure to irritants. Macrophages directed by lymphocytes are its central cells. It underlies rheumatoid arthritis, inflammatory bowel disease, atherosclerosis and organ fibrosis, and it can promote cancer.
Structure
- Infiltrate of mononuclear cells: macrophages, lymphocytes and plasma cells.
- Tissue destruction caused by the persistent agent or by the inflammatory cells.
- Attempts at repair: new vessels (angiogenesis) and fibrosis.
- Sometimes lymphoid follicles with germinal centres in the tissue (tertiary lymphoid organs), as in rheumatoid synovium and Hashimoto thyroiditis.
Function
- Classically activated (M1) macrophages, driven by IFN-γ and microbial products, kill microbes and amplify inflammation.
- Alternatively activated (M2) macrophages, driven by IL-4 and IL-13, secrete growth factors and TGF-β that promote repair and fibrosis.
- T cells keep macrophages active (Th1 through IFN-γ; Th17 through IL-17, which recruits neutrophils; Th2 through eosinophils); macrophages present antigen and secrete IL-12 and TNF.
- Plasma cells make antibodies; eosinophils (major basic protein) dominate in parasitic and allergic reactions; mast cells act in both acute and chronic phases.
Causes of chronic inflammation
| Cause | Examples |
|---|---|
| Persistent infections | Tuberculosis, Helicobacter pylori, hepatitis B and C viruses, Chagas disease, fungi and parasites |
| Autoimmune disease | Rheumatoid arthritis, systemic lupus erythematosus, inflammatory bowel disease |
| Allergic disease | Chronic asthma, atopic dermatitis |
| Long exposure to toxic or inert material | Silica (silicosis), lipids in the arterial wall (atherosclerosis), retained foreign material |
| Low-grade metabolic inflammation | Obesity, type 2 diabetes; probably part of Alzheimer disease |
Clinical notes
- Chronic inflammation fuels cancer: H. pylori gastritis and gastric cancer (frequent in the Andean regions of Colombia), ulcerative colitis and colon cancer, chronic hepatitis B and C and liver cancer.
- Chronic Chagas myocarditis, common in parts of Latin America, ends in a dilated, fibrotic heart.
- Serum amyloid A produced over years of inflammation can deposit as AA amyloid in the kidneys and other organs.
Test yourself
Think of the answer, then tap the question to see it.
Which cell is central in chronic inflammation, and what activates it classically?
The macrophage, activated classically (M1) by IFN-γ from Th1 cells and by microbial products.
Which histological features set chronic inflammation apart from acute inflammation?
A mononuclear infiltrate (macrophages, lymphocytes, plasma cells), tissue destruction, and repair by angiogenesis and fibrosis.
Which forms of chronic inflammation predispose to cancer?
H. pylori gastritis (gastric adenocarcinoma, MALT lymphoma), ulcerative colitis (colorectal cancer), chronic hepatitis B or C (hepatocellular carcinoma).
Related
- Granulomatous inflammation: caseating vs non-caseating, the causes to know
- Fibrosis in organs: TGF-β and the myofibroblast
- Outcomes of acute inflammation: resolution, abscess, scar or chronic inflammation
- Inflammation: the cardinal signs and its five steps
- Systemic effects of inflammation: fever, acute-phase proteins, leukocytosis, sepsis
- Precancerous conditions: when chronic inflammation, metaplasia or hyperplasia raise the risk
- Oncogenic viruses and H. pylori: the table to know
Related conditions
- Rheumatoid arthritis
- Crohn disease
- Ulcerative colitis
- Chronic pancreatitis
- Helicobacter pylori gastritis
- Viral hepatitis
- Atherosclerosis and dyslipidaemia
- Chagas cardiomyopathy
- Tuberculosis
- Pneumoconioses (silicosis, asbestosis, coal workers' pneumoconiosis)
- Obesity
- Gastric cancer
- Amyloidosis
Elsewhere in DurgiPedia
Microorganisms
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: 17.5 Inflammation and Fever (OpenStax (Microbiology), 2016); Crohn Disease (StatPearls (NCBI Bookshelf), 2024); Chronic Pancreatitis (StatPearls (NCBI Bookshelf), 2024); Burden of illness of rheumatoid arthritis in Latin America: a regional perspective (Clinical rheumatology, 2015).
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Representative model, for educational purposes only.