Inflammation: Definition, Causes, and Stages

Study Notes

Definition and Causes

Inflammation is a natural response of the body's immune system to injury, infection, or damage.
It is a complex biological process involving various cell types, chemical mediators, and tissues.
Causes of inflammation include:
- Infection (bacterial, viral, fungal)
- Injury (physical, thermal, chemical)
- Autoimmune disorders (e.g., rheumatoid arthritis, lupus)
- Allergic reactions
- Environmental factors (e.g., pollution, UV radiation)

Stages of Inflammation

Acute inflammation: immediate response to injury or infection, characterized by:
- Increased blood flow to the affected area
- Increased permeability of blood vessels
- Migration of white blood cells (leukocytes) to the site
- Release of chemical mediators (e.g., histamine, bradykinin)
Chronic inflammation: prolonged inflammation, often associated with:
- Tissue damage and repair
- Fibrosis (scarring)
- Immune system dysregulation

Signs and Symptoms

Cardinal signs: classic symptoms of inflammation:
- Redness (rubor)
- Swelling (tumor)
- Heat (calor)
- Pain (dolor)
- Loss of function (functio laesa)
Other symptoms may include:
- Fever
- Fatigue
- Muscle weakness
- Joint stiffness

Chemical Mediators

Cytokines: signaling molecules that regulate inflammation:
- Pro-inflammatory cytokines (e.g., TNF-α, IL-1β)
- Anti-inflammatory cytokines (e.g., IL-10, TGF-β)
Chemokines: chemotactic cytokines that attract immune cells:
- CXCL8 (IL-8)
- CCL2 (MCP-1)
Eicosanoids: lipid-derived mediators:
- Prostaglandins (e.g., PGE2)
- Leukotrienes (e.g., LTB4)

Resolution of Inflammation

Resolution phase: the process of returning to homeostasis:
- Clearance of inflammatory mediators
- Resolution of tissue damage
- Restoration of tissue function
Regulatory mechanisms: mechanisms that regulate inflammation:
- Immune suppression (e.g., Tregs, cytokine regulation)
- Anti-inflammatory cytokines (e.g., IL-10, TGF-β)
- Resolution of inflammation through specialized pro-resolving mediators (SPMs)

Inflammation Definition and Causes

Inflammation is a natural immune response to injury, infection, or damage.
It's a complex biological process involving various cell types, chemical mediators, and tissues.
Causes of inflammation include:
- Infection (bacterial, viral, fungal)
- Injury (physical, thermal, chemical)
- Autoimmune disorders (e.g., rheumatoid arthritis, lupus)
- Allergic reactions
- Environmental factors (e.g., pollution, UV radiation)

Stages of Inflammation

Acute Inflammation:
- Immediate response to injury or infection
- Characterized by increased blood flow, permeability, and white blood cell migration
- Release of chemical mediators (e.g., histamine, bradykinin)
Chronic Inflammation:
- Prolonged inflammation often associated with tissue damage and repair
- Fibrosis (scarring) and immune system dysregulation

Signs and Symptoms

Cardinal Signs:
- Redness (rubor)
- Swelling (tumor)
- Heat (calor)
- Pain (dolor)
- Loss of function (functio laesa)
Other symptoms may include:
- Fever
- Fatigue
- Muscle weakness
- Joint stiffness

Chemical Mediators

Cytokines:
- Pro-inflammatory cytokines (e.g., TNF-α, IL-1β)
- Anti-inflammatory cytokines (e.g., IL-10, TGF-β)
Chemokines:
- Attract immune cells (e.g., CXCL8, CCL2)
Eicosanoids:
- Prostaglandins (e.g., PGE2)
- Leukotrienes (e.g., LTB4)

Resolution of Inflammation

Resolution Phase:
- Clearance of inflammatory mediators
- Resolution of tissue damage
- Restoration of tissue function
Regulatory Mechanisms:
- Immune suppression (e.g., Tregs, cytokine regulation)
- Anti-inflammatory cytokines (e.g., IL-10, TGF-β)
- Resolution through specialized pro-resolving mediators (SPMs)

Description

Understand the natural response of the body's immune system to injury, infection, or damage. Learn about the causes of inflammation, including infection, injury, autoimmune disorders, allergic reactions, and environmental factors.