Chronic Inflammation

Chronic inflammation occurs when the body’s immune response is unable to clear or control a harmful stimulus effectively, leading to prolonged immune activity and, potentially, local tissue damage. Ordinarily, the immune system responds to infection or injury by dispatching white blood cells like neutrophils, macrophages, and activated T lymphocytes to the affected area. These cells work to neutralize or remove harmful agents. If they are successful, inflammation subsides with minimal tissue impact. However, when the immune system cannot fully eliminate a stimulus—such as persistent microorganisms—a state of chronic inflammation can develop.

 

In cases of chronic inflammation, immune cells continuously gather, causing tissue to become progressively more damaged. For example, infections with bacteria like those that cause tuberculosis and leprosy lead to the formation of a granuloma. Granulomas are clusters of immune cells surrounded by connective tissue. These structures form when the immune system tries to wall off pathogens it cannot fully eradicate due to their protective cell walls, which shield them from immune attacks.

 

In addition to infections, overactive or prolonged immune responses, known as hypersensitivity reactions, can also lead to chronic inflammation. These hypersensitivity reactions are categorized into types (outlined in the Gell and Coombs classification) based on whether antibodies or immune cells drive the response. Such prolonged immune activity can inadvertently damage nearby healthy tissues, causing “bystander” tissue injury.

 

Conditions commonly associated with abnormal CRP and/or ESR

Laboratory Indicators of Chronic Inflammation

Inflammation-related changes in the body can be observed through various laboratory tests, helping clinicians assess and monitor inflammation levels. Common indicators include:

1. Leucocytosis: This is an increase in white blood cell count, reflecting the immune system's recruitment of cells to the inflammation site. Neutrophils and monocytes are particularly involved in chronic inflammatory responses.
2. Platelet Count: Chronic inflammation often leads to a higher platelet count.
3. Normocytic Normochromic Anemia: Chronic inflammation can cause a type of anemia characterized by red blood cells that are normal in size and color, often referred to as anemia of chronic disease.
4. C-Reactive Protein (CRP): Produced by the liver, CRP is a critical marker of acute inflammation. Its levels can increase as much as 1,000 times within just a few hours after inflammation begins. CRP is useful in monitoring disease progression, as it decreases rapidly when inflammation subsides. Certain diseases, like systemic lupus erythematosus (SLE) or ulcerative colitis, may show minimal CRP elevation despite clear signs of inflammation.
5. The ESR indicates the rate at which red blood cells sink to the bottom of a blood sample tube. Higher ESR often indicates an inflammatory process, as inflammation-related plasma proteins promote red blood cell clumping. Although ESR can suggest inflammation, CRP is generally preferred for its sensitivity and reliability.
6. Plasma Viscosity: This measure of blood thickness can also indicate inflammation, as higher plasma protein concentrations increase viscosity. Plasma viscosity is more stable than ESR, which can be influenced by factors unrelated to inflammation, such as red blood cell shape or delay in testing.

 

Diagnostic Imaging and Additional Tests

In cases of unexplained or severe inflammation, doctors may use imaging tools like chest X-rays, CT scans, and MRI to identify underlying causes, including infections, abscesses, or malignancies. Advanced tests such as echocardiography or white blood cell scans may also be warranted if there is a suspicion of infection in specific tissues like the heart or bones.

Chronic inflammation is a complex condition that demands careful diagnosis and monitoring to manage the underlying cause effectively and to limit potential tissue damage. By recognizing chronic inflammation’s signs and understanding the tests that indicate inflammation levels, clinicians can better address these persistent immune challenges.

Diseases Caused by Chronic Inflammation

1. Cardiovascular Disease: Chronic inflammation contributes to plaque buildup in the arteries, leading to heart disease, atherosclerosis, and stroke.
2. Rheumatoid Arthritis (RA): A long-term autoimmune condition that targets the joints, leading to pain, swelling, and joint damage.
3. Type 2 Diabetes: Inflammatory responses are linked to insulin resistance, which is a major factor in the development of type 2 diabetes.
4. Inflammatory Bowel Disease (IBD): This category encompasses conditions like Crohn's disease and ulcerative colitis, which both cause inflammation in the digestive system.
5. Asthma: Chronic inflammation makes airways sensitive, leading to symptoms like coughing, wheezing, and shortness of breath.
6. Chronic Obstructive Pulmonary Disease (COPD): Inflammation in the lungs from smoking or pollutants causes breathing difficulties and long-term lung damage.
7. Cancer: Persistent inflammation can lead to cellular damage and increase the risk of cancers such as liver, colon, and gastric cancers.
8. Alzheimer’s Disease: Inflammation in the brain is associated with neuron damage, which may contribute to cognitive decline.
9. Psoriasis: A chronic inflammatory skin disease where the immune system speeds up skin cell production, causing patches of itchy, scaly skin.
10. Systemic Lupus Erythematosus (SLE): Lupus is an autoimmune disease marked by widespread inflammation that can affect the skin, joints, kidneys, and other organs.
11. Multiple Sclerosis (MS): Chronic inflammation damages the protective covering of nerve fibers, causing neurological symptoms and disability over time.
12. Gout: An inflammatory condition caused by high uric acid levels leading to crystal deposits in the joints, resulting in severe pain and swelling.
13. Chronic Sinusitis: Persistent inflammation in the sinuses can cause chronic sinus infections, leading to congestion, headaches, and facial pain.
14. Hashimoto’s Thyroiditis: An autoimmune condition where chronic inflammation damages the thyroid gland, leading to hypothyroidism (underactive thyroid).
15. Fibromyalgia: While the exact cause is unknown, chronic inflammation is thought to contribute to the pain and fatigue seen in fibromyalgia.
16. Celiac Disease: An autoimmune disorder where gluten triggers chronic inflammation in the small intestine, leading to digestive problems and malabsorption.
17. Sjögren's Syndrome: An autoimmune disorder in which chronic inflammation affects moisture-producing glands, leading to dry eyes and dry mouth.
18. Ankylosing Spondylitis: A type of arthritis primarily affecting the spine, where chronic inflammation can cause spinal bones to fuse, leading to reduced flexibility.
19. Obesity-Related Chronic Inflammation: Excess body fat, particularly around the abdomen, can trigger low-grade chronic inflammation, which may increase the risk of other diseases like heart disease and diabetes.
20. Dermatomyositis: An inflammatory disease marked by muscle weakness and skin rashes, often associated with immune system abnormalities.
21. Pulmonary Fibrosis: Chronic inflammation in the lungs causes scar tissue to build up, leading to breathing difficulties and reduced lung function over time.
22. Atherosclerosis: Chronic inflammation in blood vessels contributes to plaque buildup, increasing the risk of heart attack, stroke, and other cardiovascular problems.
23. Chronic Hepatitis: Persistent liver inflammation, often from hepatitis B or C infections, can lead to liver damage, cirrhosis, and increased risk of liver cancer.
24. Osteoarthritis (OA): Although OA is primarily a wear-and-tear disease, inflammation also plays a role, especially in advanced stages, leading to joint pain and stiffness.
25. Interstitial Cystitis: This chronic inflammatory condition affects the bladder, causing bladder pain, frequent urination, and discomfort.