What Are the 5 Classic Signs of Inflammation?

Inflammation is a natural process by which the body’s immune system fights against injuries, infections, chemicals, and radiation. It is characterized by the following signs:

• Redness
• Swelling
• Heat
• Pain
• Loss of Function

1. What Is the Main Cause of Inflammation in the Body?

There are many causes of inflammation that is triggered by the body’s immune system:

• Injury such as a splinter, scrapes, trauma, or any damage caused by a foreign object.
• Pathogens, including viruses, bacteria, parasites, or fungi
• Chemicals such as glucose, fatty acids, chemical irritants (e.g., acids), toxins, and alcohol
• Radiation such as sunburns
• Biological such as damaged cells in the body

2. What Happens During Inflammation?

Inflammation involves the contribution of different immune cells which release substances known as inflammatory mediators, including hormones such as histamine and bradykinin [1].

These inflammatory mediators induce vasodilation (dilatation of the vessels) which promotes the blood flow in the injured tissue and the recruitment of inflammatory cells (neutrophils, monocytes, and endothelial cells) to the site of injury.

The vasodilatation and the blood rush into the injured tissue result in redness and heat which are 2 signs of acute inflammation.

The pain associated with inflammation is caused by the irritation of local nerves by the inflammatory mediators.

These inflammatory cells have specific roles during acute inflammation:

• Neutrophils initiate the phagocytosis and killing of pathogens to decontaminate the wound, while also promoting cell proliferation and angiogenesis.
• Monocytes also contribute to the phagocytosis and killing of pathogens, and become macrophages, which remove dead cells, and support cell proliferation and tissue restoration following injury.
• Endothelial cells are the building blocks for vessels, and during wound healing, these cells generate new vessels (angiogenesis) to satisfy the metabolic demands of the highly proliferative healing tissue. 

Depending on the site of injury, a transitory loss of function can be observed due to tissue damage, swelling, or pain during inflammation.

3. How long Does Inflammation Last For?

Inflammation can be acute lasting for a few days (2-3 days) or chronic which lasts for a longer time until the insult is resolved.

What Are the Outcomes of Inflammation?

The resolution of acute inflammation (initial inflammation) depends on the causes and the extent of tissue damage. It is characterized by the following outcomes:

• Complete repair of the injured tissue and without scars
• Resolution of the inflammation with the formation of a scar or fibrosis
• Formation of an abscess
• Chronic inflammation if the initial inflammation persists and remains unresolved

The complete repair of the injured tissue or the formation of scars is mediated by a process known as wound healing.

Wound healing is a natural reaction of our body to tissue damage and involves crosstalk between different cells, cytokines, inflammatory mediators, and the vascular system to repair the damaged tissue.

4. What Are the Most Common Inflammatory Diseases?

The most common inflammatory diseases are associated with chronic mediated inflammation which includes the following diseases [2]:

• Rheumatoid Arthritis
• Cardiovascular diseases
• Inflammatory Bowel Disease (IBD) 
• Allergic Asthma
• Chronic obstructive pulmonary disease (COPD)
• Diabetes
• Chronic Kidney Disease
• Cancer

4.1. Rheumatoid Arthritis

Rheumatoid arthritis is due to a local chronic inflammation that results in the infiltration of immune cells into the joints and the release of inflammatory mediators such as cytokines.

4.2. Cardiovascular diseases

Atherosclerosis is associated with a chronic inflammation that leads to heart diseases such as stroke, and myocardial infarction.

4.3. Inflammatory Bowel Disease (IBD)

Inflammatory Bowel Disease (IBD) is a group of chronic inflammatory disorders affecting the bowels that are caused by ulcerative colitis (inflammation of the colon due to ulcer) or Crohn’s disease.

4.4. Allergic Asthma

Allergic asthma is due to the inflammation of the airways caused by the inhalation of an allergen which results in their swelling and tightening affecting breathing.

4.5. Chronic obstructive pulmonary disease (COPD)

COPD is a chronic inflammatory lung disease due to the exposure of the airways to harmful particles or gases causing inflammation that obstruct airflow in the lung leading to breathing difficulties.

4.6. Diabetes

One of the characteristics of diabetes is the infiltration of immune cells, such as macrophages, into pancreatic tissue, and their release of pro-inflammatory molecules responsible for inflammation.

4.7. Chronic Kidney Disease (CDK)

Chronic kidney disease or chronic kidney failure is a progressive loss of the function of the kidney resulting from the accumulation of body wastes and fluids in the blood.

One of the causes of chronic kidney disease is the inflammation of the glomeruli that filter blood for the elimination of waste and fluids in urine.

4.8. Cancer

Chronic inflammation is one of the characteristics of different types of cancer from various origins (Prostate, hepatic, colorectal, ovarian, pancreatic, and lung cancers).

4.9. Neurodegenerative diseases

Neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease are associated with the production of proinflammatory molecules by the brain resident immune cells and microglia which cause brain damage.

5. What Is the Difference Between Inflammation and Infection?

Infections cause inflammation which is a natural process by which the body’s immune system fights against pathogens, including bacteria, viruses, fungi, or parasites.

6. How Do You Get Rid of Inflammation in the Body?

Unlike acute inflammation, chronic inflammation can last for a longer period, and therefore, requires management and treatment through lifestyle changes or medications [3].

6.1. Lifestyle changes

6.1.1. Diet

A diet rich in glucose and processed food rich in saturated fat and trans fats promotes inflammation leading to cardiovascular diseases and type 2 diabetes. Hence, a low glucose diet and avoiding processed food can prevent inflammation.

A diet rich in vegetables and fish oils, nuts, mung bean, green and black teas, and certain species (e.g., ginger, turmeric) can prevent or reduce inflammation as they contain antioxidants and polyphenols which have anti-inflammatory properties.

6.1.2. Physical Activity

In addition to weight loss associated with exercising, physical activity also results in energy consumption with reduces the levels of proinflammatory molecules in the body.

6.2. Medications

The most used anti-inflammatory medications include nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids. 

Nonsteroidal anti-inflammatory drugs (NSAIDs) such as naproxen, ibuprofen, and aspirin, alleviate pain by inhibiting the function of the enzyme cyclooxygenase (Cox) involved in the synthesis of the proinflammatory molecules, prostaglandins.

Corticosteroids are prescribed for some inflammatory conditions such as arthritis, asthma, systemic lupus, and sarcoidosis.

Conclusion

Acute inflammation is a natural process by which the body’s immune system responds to injuries and infections. Acute inflammation takes a few days to resolve, leading to a complete repair of damaged tissues, fibrosis (scars), formation of an abscess, or chronic inflammation.

Chronic inflammation can be associated with several inflammatory diseases such as rheumatoid arthritis, allergic asthma, cancer, diabetes, cardiovascular diseases, chronic kidney disease, COPD, inflammatory bowel disease, and neurodegenerative diseases.

The treatment of chronic inflammation includes lifestyle changes, physical activity, and medications using anti-inflammatory drugs such as NSAIDs and corticosteroids.