Innate Immunity Inflammation Flashcards
Innate Immunity (1st line defense) -Physical Barriers
Epithelial Cells of the:
- Skin
- GI
- GU
- Respiratory system
Innate Immunity
- Includes Natural Barriers (physical, mechanical, biochemical)
- Inflammation
Innate Immunity (1st line defense) -Mechanical
Removes bacteria by:
- Coughing
- Sneezing
- Vomiting
- Flushing - urine
Innate Immunity (1st line defense) -Epithelial Cell-derived Chemicals
- Lysozyme
- enzyme attacks the cell walls of GRAM POSITIVE BACTERIA - Cathelicidin / Defensins
- Antimicrobial peptides that disrupts bacterial membranes and kills them
Innate Immunity (1st line defense) -Normal Flora
- Compete w/ pathogens for nutrition and prevent attachment to epithelium
- Helps w/ digestion / produces biotin and Vit K (clotting)
- Assits w/ absorption of Ca, Fe, Mg
Innate Immunity: 2nd Line Defense
-Inflammation
- Protective process
- May result from injury, infection
- Stimulates healing
- Prevent further damage and progressive deterioration
Inflammation
-Signs & symptoms
- Redness – decreased blood flow & increase RBC concentration to area
- Heat – pooling of blood
- Swelling – leakage of plasma proteins
- Pain - Bradykinin & prostaglandin’s
Inflammation Goals
- Limit and control the inflammatory process
- Prevent and limit infection and further damage
- Initiate adaptive immune response
- Initiate healing.
Inflammation:
-Development process
- Damage to Tissue
- Vasodilation
- Increased Vascular permeability
- WBC’s adherence to inner walls of vessels
Cathelicidin
- Cathelicidin is produced by epithelial cells of the skin, gut, Urinary tract, Respiratory tract
- Antimicrobial peptides that disrupt bacterial membranes and kills them
Cathelicidins
-Action
- Bacteria have cholesterol-free cell membranes into which cathelicidin can insert and disrupt the membrane, killing the bacteria
Epithelial Cell-Derived Chemicals
Alpha Defensin’s
- Often require activation by proteolytic enzymes
- Rich in the granules of neutrophils
- May contribute to the killing of bacteria by those cells.
Epithelial Cell-Derived Chemicals
Beta Defensins
- Synthesized in active forms
- Can kill bacteria the same way as cathelicidin
- Found in epithelial cells lining:
- respiratory, urinary, and intestinal tracts as well as skin - May help protect epithelial surfaces from infection with adenovirus & HIV
Epithelial Cell-Derived Chemicals
Collectin’s
- React w/ carbs on the surface of a wide array of pathogenic microorganisms and help cells of the INNATE immune system (MACROPHAGES) recognize and kill microorganisms
Epithelial Cell-Derived Chemicals
-Mannose-Binding lectin (MBL)
- Powerful activator of a plasma protein system (COMPLEMENT) resulting in damage to bacteria or increased recognition by macrophages
Normal Flora Benefits
- Digest Fatty acids, large polysaccharides, and other dietary substances
- Produce Biotin and Vitamin K
- Assist in absorption of ions, such as Ca, Fe, and Vitamin K
- Train the adaptive immune system by inducing growth of gut-associated lymphoid tissue (Where cells in the adaptive immune system reside)
Prolonged treatment with Broad-Spectrum Antibiotics
Can lead to:
- Candida albicans
- Clostridium difficile
Opportunistic Microorganisms
- Can cause disease if the individual’s defenses are compromised
- Psudomonas aeruginosa
Plasma Protein Systems
- Complement System
- Clotting System
- Kinin System
Compliment Cascade
-Overview
- Factors produced by compliment cascade are among the body’s MOST POTENT defenders against bacterial infection
Compliment Cascade
-Most Important function
- most important function of the complement cascade is:
- ACTIVATION OF C3 & C5 - Resulting in:
- Opsonins
- chemotactic factors
- anaphylatoxins
Compliment Cascade
-Opsins
- Coat the surface of bacteria and increase their susceptibility to being phagocytized (eaten) & killed by neutrophils and macrophages
Compliment Cascade
-Chemotactic Factors
- Diffuse from a site of inflammation and attract PHAGOCYTIC CELLS to that site
Compliment Cascade
-Anaphylatoxins
- Induce rapid degranulation of mast cells
- release of histamine that induces vasodilation and increased capillary permeability
Compliment Cascade
-Activation of complement components C5b through C9
- Membrane attack complex
2. Results in a complex that creates pores in outer membrane
Compliment Cascade
-Most potent products
- C3b (opsonin)
- C3a (anaphylatoxin)
- C5a (anaphylatoxin, chemotactic factor)
Pathways that control the Activation of Complement (3)
- Classical Pathway
- Lectin Pathway
- Alternative Pathway
Pathways that control the Activation of Complement (3)
-Classical Pathway
- Primarily activated by antibodies (proteins of the acquired immune system)
- Antibodies activate the 1st component of complement, C1.
- C1 leads to activation of other complement components leading to activation of C3 & C5
Antibodies of the Acquired immune response can use the complement system to kill bacteria and activate inflammation
Pathways that control the Activation of Complement (3)
-Alternative Pathway
- Activated by several substances found on the surface of infectious organisms (lipopolysaccharides, endotoxin)
- Uses Unique proteins (Factor B, D, and properdin) to form complex that activates C3
- C3 activation leads to C5 activation and convergence w/ the classical pathway
Can Directly activate complement system by infectious organisms w/out antibody presence ***
Pathways that control the Activation of Complement (3)
-Alternative Pathway (Activation Summary)
- Directly activate the complement system by presence of certain infectious organisms W/OUT ANTIBODY BEING PRESENT
Pathways that control the Activation of Complement (3)
-Lectin Pathway
- Similar to classical pathway but is INDEPENDENT OF ANTIBODY
- Activated by Mannose-binding lectin (MBL)
- MBL is similar to C1 and binds to bacterial polysaccharides containing the carbohydrate mannose
Pathways that control the Activation of Complement (3)
-Summary
Complement cascade can be activated by:
- Opsonization
- Anaphylatoxic activity – resulting in mast cell degranulation
- Leukocyte chemotaxis
- Cell lysis
Clotting System
-Purpose
- Plug damaged vessels and stop bleeding
- Trap microorganisms and prevent their spread
- Provide framework for future repair and healing
Clotting Cascade
-Activation by substances
Substances that are released by tissue injury and infection:
- Collagen
- Proteinases
- Kallikrein
- Plasmin
- Endotoxins (bacterial products)
Clotting Cascade
-Activation Pathways
- Tissue (Extrinsic) Pathway
2. Contact activation (Intrinsic) Pathway
Clotting System
-Tissue (Extrinsic) Pathway
- Activated when there is TISSUE INJURY and membrane-bound or soluble tissue factor (TF) (also called tissue thromboplastin), a substance released by damaged ENDOTHELIAL CELLS in blood vessels, REACTS w/ ACTIVATED FACTOR (VIIa)
Clotting System
-Tissue Factor (TF)
- A substance released by damaged endothelial cells in blood vessels
Clotting System
-Contact Activation (Intrinsic) Pathway
- Activated w/ abnormal vessel wall and Hageman factor (factor XII) contacts negatively charged SUB-ENDOTHELIAL substances
- Killikrein & Kininogen can also activate factor XII
- Clotting pathways converge at factor X
Kallikrein & Kininogen
- Can activate factor XII in the contact activation (intrinsic) pathway
Factor X
- Activation of factor X begins a common pathway leading to activation of fibrin that polymerizes to form a fibrin clot
Clotting Pathway
-Fibrinopeptides (FP’s)
- Activation of the clotting cascade produces fragments known as FP’s A & B that enhance the inflammatory response
- FP’s are released from fibrinogen when fibrin is produced
- Both Fibrinopeptides are CHEMOTACTIC for neutrophils and increase vascular permeability by enhancing effects of BRADYKININ.
Kinin Cascade
-Activation
- Both the clotting and Kinin systems can be initiated through activation of Hageman factor (factor XII) to factor XIIa.