Innate Immune Response (Ch14)

Overview of Innate Defense System

First lines of Defense Physical Barriers Antimicrobial substances Skin Mucous membranes Antimicrobial substances Lysozyme Peroxidase enzyme Lactoferrin Defensins Normal Flora

Epithelial Barriers

Skin as the first line of defense Intact skin protects Epidermis Dermis

Mucous membranes line the interior of the body

Ciliated cells are important…where?

Antimicrobial Substances

Microbial Barriers Normal flora (biota) play a role in keeping the body protected Competitive exclusion E. coli produce bacteriocins which kill Salmonella and Shigella

Cells of the Immune System Cells move from one system to the next Found in blood, developed from bone marrow What are some of these cells?? Granulocytes (neutrophils, basophils, eosinophils) Mononuclear phagocytes Dendritic cells Lymphocytes

Dendritic cells Branched cells, important in adaptive immunity Develop from monocytes, engulf material and bring it to other cells for analysis

How do cells of the immune system communicate? Cytokines Chemokines Colony-stimulating factors Interferons Interleukins Tumor Necrosis factors

Cytokines and their function

Interferons Three types of glycoproteins Alpha Beta Gamma Produced by virus infected host cells, induce mRNA for antiviral proteins Gamma Produced by lymphocytes

Interferons inhibit viral replication

Sensor systems in the blood, tissues and cells Can detect signs of tissue damage or microbial invasion Respond by Detecting parts of bacteria/viruses using pattern recognition receptors (PRRs) Directly destroy bacteria using complement Recruit other components of host defense

Pattern Recognition Receptors Toll-Like receptors (TLRs) Membrane bound receptors which detect bacterial parts NOD-like receptors (NLRs) Cytoplasmic proteins detect bacterial parts RIG-like receptors (RLRs) Cytoplasmic proteins detect viral RNA

Toll-like receptors (TLRs) A type of PRR Recognize peptidoglycan, lipopolysaccharide, flagellin, certain nucleotide sequences unique to bacteria

Toll-like receptors

NOD-like receptors (NLRs)

RIG-like receptors Cytoplasmic proteins which detect viral RNA in a cell Activate secretion of interferon and inflammatory response chemicals Overall goal is to inhibit viral replication

Complement Proteins are part of the Complement system Consists of a collection of 9 interacting proteins found in blood and tissues Activation of these proteins promote Opsonization Inflammatory response Lysis of foreign cell

How are the complement proteins activated?

Regulation of the complement system

What have we covered so far? The innate immune system is composed of Cells Chemicals released by cells to communicate with each other Receptors to recognize invaders We need to look at the processes of phagocytosis and inflammation

How do phagocytes work?

Fever is a nonspecific response Il-1 increases T lymphocytes Decreases available iron Increases cellular reactions

Inflammation response What are the key cells involved? What are the four key symptoms of inflammation? What activates the inflammation response?