Inflammation and Immunity Associated Diseases and Disorders
Inflammation is a complex physiological response of the immune system to harmful stimuli such as pathogens, damaged cells, or irritants. It is a protective mechanism aimed at removing the initial cause of injury, clearing out damaged tissues, and initiating tissue repair. Immunity encompasses the body’s defense systems, which include innate and adaptive responses.
1. Types of Immunity
• Innate Immunity: The first line of defense, non-specific, includes physical barriers (skin, mucous membranes), immune cells (macrophages, neutrophils, NK cells), and soluble factors (complement proteins).
• Adaptive Immunity: Specific defense mechanism involving lymphocytes (B and T cells) that provide memory and long-term protection.
2. Physiological Process of Inflammation
The inflammatory response involves the following steps:
1. Recognition of injury or pathogen by immune cells via pattern recognition receptors (PRRs).
2. Release of inflammatory mediators (cytokines, chemokines, prostaglandins).
3. Increased vascular permeability and blood flow to the affected area.
4. Recruitment of immune cells to eliminate the cause of injury.
5. Resolution phase to restore tissue homeostasis and prevent chronic inflammation.
3. Key Inflammatory Mediators
• Cytokines: TNF-α, IL-1β, IL-6 – promote leukocyte recruitment and fever.
• Chemokines: Direct migration of immune cells to sites of inflammation.
• Eicosanoids: Prostaglandins, leukotrienes – modulate vascular tone and permeability.
• Histamine: Increases vascular permeability and vasodilation.
• Complement system: Enhances phagocytosis and cell lysis.
4. Physiological Roles of Inflammation
• Pathogen elimination and tissue repair.
• Activation of adaptive immune responses.
• Containment of infection.
• Removal of damaged or dead cells.
5. Resolution of Inflammation
Resolution involves the clearance of inflammatory cells and mediators, repair of damaged tissues, and restoration of normal tissue function. Specialized pro-resolving mediators (SPMs) like resolvins, protectins, and maresins actively turn off inflammation.
6. Relationship Between Inflammation and Immunity
Inflammation is an essential part of the innate immune response and acts as a bridge to adaptive immunity. Cytokines produced during inflammation activate and direct adaptive immune responses, while antibodies and cytotoxic T cells help eliminate persistent threats.
7. Physiological Balance
While acute inflammation is protective, uncontrolled or chronic inflammation can lead to tissue damage and pathology. The immune system must maintain a balance between effective defense and prevention of excessive damage.