Table of Contents
Introduction:
An acute inflammatory response is a physiological response to an injury, and it is also called inflammation. The short-term response is acute inflammation and long-term, and the long-term response is chronic inflammation. The cellular and molecular changes post-injury reduce impending injury and infections. Any long-term inflammation can lead to chronic inflammatory diseases.
What Is Acute Inflammatory Response?
The immune system’s immediate response to trauma or injury is acute inflammation. This damage can be thermal, mechanical, chemical, radiation, or infection. Acute inflammation can present as acute bronchitis (respiratory infection), sore throat, wound or trauma, or appendicitis.
It has four characteristic features. They are as follows:
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Rubor - Redness due to increased blood flow.
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Calor - Localized increase in temperature or heat.
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Tumor - Swelling occurs due to increased fluid loss into extracellular spaces.
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Dolor - Pain that occurs due to stimulation of nerves.
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Functio Laesa - This causes loss of function.
What Are the Causes of Acute Inflammatory Response?
The causes or triggers of the acute inflammatory response are mainly injury or trauma, which can be classified into two main groups:
1. Exogenous Agents: Consists of microbial agents and non-microbial agents.
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Microbial Agents: Include pathogen-associated molecular patterns. These consist of microorganisms and virulent agents, which trigger the inflammatory response.
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Non-Microbial: Causes include allergens, toxic compounds, irritants, and foreign bodies, including silica and asbestos.
2. Endogenous Agents: Include signals released by the dead, damaged, malfunctioned, or stressed tissue.
The causes can also be classified as:
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Infectious: Agents include bacteria, viruses, and other microorganisms.
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Non-Infectious: Agents include physical injuries like frostbite, burns, physical injury, foreign bodies, trauma, ionizing radiation, and chemical compounds.
What Is the Purpose of Acute Inflammatory Response?
The clinical significance or purpose of acute inflammatory response is as follows:
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Cardiovascular Disease: In atherosclerosis, inflammatory mediators play a major role. An increase in the levels of chemokines and cytokines is seen. The first sign of cardiac stress is inflammation.
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Pancreatitis: Pancreatitis is a genetic disease due to alcohol abuse or pancreatic duct obstruction. This infection activates inflammatory cells like neutrophils and granulocytes. They further secrete inflammatory cytokines.
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Liver Infection: Inflammation will try to protect the liver from further injury and infection. When this infection exceeds, it will cause liver cell injury, metabolic changes, and ischemia. The infectious agent in such cases is the hepatitis virus, ischemia (reduced blood flow), alcoholic hepatitis, or drug-induced hepatitis.
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Kidney Infection: Kidney infections are caused by endothelial cells of renal tubules. These cells secrete cytokines which bring about inflammation.
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Intestine Infections: Inflammatory bowel disease is caused due to gut microbial flora. They induce cytokines. This is seen in inflammatory bowel diseases, such as Crohn's disease and ulcerative colitis.
What Are the Phases of Acute Inflammatory Response?
Acute inflammatory response has two phases or processes; vascular phases, which involve a change in the blood vessels, and cellular phase, which consists of a change in cellular components.
1. Vascular Phase:
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Vasodilatation - In this phase, the blood vessels surrounding the injury dilate. This increases the blood flow to the injured area. The cells of the blood vessels are called endothelial cells. These cells initially enlarge, followed by contraction.
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Exudation of Fluid - The contraction of endothelial cells creates spaces between the cells to increase fluid loss. This loss of fluid in the extracellular space causes swelling.
An increase in the tissue fluid increases the migration of inflammatory proteins like complement and immunoglobulins. This increases lymphatic drainage and helps clear pathogens and cellular debris.
2. Cellular Phase:
The neutrophil is an important cell in inflammatory reactions. The release of chemotaxis follows injury; these are the mediators that help neutrophils attract to the injury site. The neutrophils migrate in the following stages:
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Margination: The neutrophils line up against the endothelial cells.
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Rolling: Neutrophils are in close contact with the endothelial cells and roll along them.
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Adhesion: Neutrophils attach to the endothelial cell wall.
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Emigration: Neutrophils move through the gaps between the endothelial cells to the affected area. Once the neutrophils are in contact with the pathogen, the pathogen is engulfed to form a phagosome. This process is called phagocytosis. The phagosome is destroyed by an enzyme called lysozyme, which is an oxygen-independent reaction. Another way of phagosome destruction is by free radical formation, which is an oxygen-dependent reaction.
The injury can show the following outcomes:
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Complete repair and resolution.
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In cases of increased inflammation, fibrosis (scarring or thickening of tissues) and scar formation occur.
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If the damage continues, it can lead to chronic inflammation.
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If bacteria invade the site, it can lead to abscess (pus buildup) formation.
How to Diagnose Inflammation?
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Increased levels of inflammation increase the levels of biomarkers, substances that increase in the body due to inflammation. C-reactive protein levels can be assessed.
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The erythrocyte sedimentation rate test measures the inflammation, the rate at which red blood cells are immersed in the blood tube. Increased inflammation can increase the thickness of blood.
How to Treat Inflammation?
Inflammation does not require any specific treatment. The following measures can be taken to control inflammation:
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Adequate rest is needed.
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Cold fomentation with the use of ice packs can provide symptomatic relief.
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Good care of the wound to prevent infection.
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One can consume a diet consisting of food with anti-inflammatory properties. A diet rich in fish, fish oil, green leafy vegetables, olive oil, broccoli, avocados, green tea, mushrooms, and tomatoes.
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Bacterial or fungal infections can require the prescription of antibiotics or antifungals.
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Nonsteroidal anti-inflammatory drugs (NSAIDs) can help reduce pain, swelling, and fever, as they inhibit inflammatory enzymes. Ibuprofen, Naproxen, and Aspirin are a few such drugs available over the counter. Consult the physician before the long-term use of such medications.
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Pain relief can be obtained with the use of over-the-counter Paracetamol or Tylenol.
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Corticosteroids are a group of steroid drugs that help in the treatment of arthritis (joint inflammation), dermatitis (skin inflammation), hepatitis (liver inflammation), asthma (chronic lung disease), and certain allergic reactions.
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Topical analgesics are used for acute pain. Topical creams containing Ibuprofen or Diclofenac can help relieve topical inflammatory symptoms.
How to Prevent Inflammation?
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Maintenance of healthy weight and regular exercise.
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Avoid smoking.
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Limit alcohol intake.
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Stress management techniques like meditation and yoga.
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Try to avoid fried and processed food, red meat, sugar-containing drinks, and saturated fats in the diet.
Conclusion:
Inflammation is the physiological response of the body to any sort of injury or infection. Based on the time taken to develop these responses, the inflammation can be classified into acute (shorter duration) or chronic (longer duration). Inflammation is mostly accompanied by redness, swelling, and pain. Inflammation does not require any specific treatment. The symptoms can be easily managed and avoided by adopting a healthy lifestyle.
