Innate Immunity Overview Flashcards
Innate Immunity
An acient defense form that is found in all multicellular plants and aninmals
What are the 2 major components of innate immunity?
Physical/chemical barriers and Cellular responses to infection
What makes up the physical and chemical barriers against infection?
- epithilial layers of the skin
- mucosal and glandular tissue surfaces (mucoid barriers)
- cilia (mechanical removal of foreign material)
- commensal microbiota
- chemical barriers (low pH, degrative enzymes, and directed mucus flow)
- Antimicrobial peptides and proteins
Chemical Barriers
Molecular factors that provide innate immune protection against infection
Antimicrobial peptides and proteins
Molecules released by several cell types. Some are constitutively secreted, whereas others are induced upon activation of innate receptors. These can directly kill microbs
peptides
<100 amino acids
Proteins
> 100 amino acids
What makes up the cellular responces to infection?
- triggered bt the cell surface or intracellular innate PRRs
- Phagocytosis
- production of antimicrobial substances as well as cytokines and chemokines to induce inflammation
Phagocytosis
The cellular uptake of particulate materials by engulfment
Inflammation
Tussue response to infection or damage that eliminates/ contains the insult. Classical signs include heat, pain, redness, swelling, and loss of function.
Epithelial Cells
A specilized cell type that protects the body from external stimuli. Lines all body cavities continuous with the external surface
Endothelial Cells
Specilized cells that line organs that are not continuous with the external surface such as the peritoneal cavity ans the inner syrfaces of blood vessels
Mucus
An aqueous, viscous fluid secreted by goblet cells in the eithelial layer that protects it from dehydration and physical injury. Consists of highly glycosylated glycoproteins (mucins) as well as proteoglycans, lipids, DNA, and other proteins
Goblet Cells
Mucous Producing cells
Where is most of our mucus produced?
In the GI tract (protects stomach lining from the stomach acid and limits bacterial interactions withh intestinal epithelial cells)
There is less of a barrier in the small intestine compared to other areas of the GI tract to allow for absorbtion of nutrients during digestion
Cilia
Hairlike projections onn cells that can propel mucus with trapped microbes out of the respiratory tract
Decribe how cilia is a physical barrier against infection?
The synchronous movement of cilia propels mucus and particles upward from the lungs and downwards from the nose to be swallowed or expelled by coughing/ sneezing
What fluids in our body conain antimicrobial substances?
Saliva, tears, urine, and breast milk
Commensal Microbiota
The diverse community of microbes that coexist with our barrier tissues without causeing damage. They provide diverse benifits to barrieer tissues throughout the body. The species of bacteria are reigonally determined throughout the body.
These direcctly inhibit the growth of pathogens by controlling the local microenviroment (their metabolites can also enhance barrier strength). They ARE part of the innate immune system.
What cells produce AMPs?
Neutrophils, monocytes, epithelial cells, and salivary mammalian gland cells
WHat are the different ways the anti-microbial peptides/ proteins (AMPs) target microbes?
They can…
- Cleave essencial cellular components
- Hyrolyze membranes
- Disrupt essencial cellular structures/ processes
- Bind to the microbe
- Block the access of crucial metabolites/ components to the microbe
- Create channels in the membranes
Describe the major properties of AMPs.
- peptides (10-50 aa); proteins (>100 aa)
- Cysteine rich (creating intramolecular disulfide bonds)
- Amphipathic (water and fat loving)
- They interact with acidic phospholipids in bacterial membranes
- They can disrupt membrane integrity (through hydrolysis, enzymatic cleavage or disruption)
- They can inhibit nucleic acid and protein synthesis
How do local AMPs control the reigonal microbiota?
Different cells in different areas of the body contribute different barriers/ AMPs which target specific bacteria.
Example: on our fingers there are different AMPs produced that do not harm our commensal bacteria S, aureus but it will target foreign bacteria such as E. coli which is normally found in our GI tract
Antigen presenting cells (APCs)
Cells that communicate the infection to the lymphoid cells, which the corrdinate the adptive response to the infection
Primary Lymphoid Organs
Place where lymphoid precursors mature into antigenically commited, immunocompetent cells
These lymphoid organs are the bone marrow and thymus
Secondary lymphoid organs
Organs and tissue which mature, immunocompetent lymphocytes encounter trapped antigens and are activated into effector cells
These lymphoid organs include lymph nodes, spleen, and specilized mucosal tissues in the gut
