Exam 3 Lecture 13: Mucosal Immunity Flashcards
What is mucosal tissue
Widely distributed in the body
Impacted by commensal microbiota
“Outside the body” susceptible to infection
Huge surface area
What are examples of mucosal immunity
Respiratory tract, GI tract, urogenital tract, mammary tissue, salivary and lacrimal glands
What is mucus and why is it important
Mucus made of glycoproteins secreted by epithelial cells
-huge size with repeating motifs
-negative charge
-cross-linking increases viscosity
What role do commensal microbes play in mucosal immunity
Provide nutrients
Protect against toxins
Physical barrier
Educate secondary lymphoid tissue
What is the MALT
Mucosal associated lymphoid tissue
Sit just under mucosal layer
Where T and B cells meet their antigens
Includes GALT (peyer’s patches), BALT, NALT
How is mucosal immune response different from systemic response
More vulnerable to damage
Limited imflammation
How are innate and adaptive mucosal responses in the MALT different than systemic responses
Systemic: pro inflammatory cytokines
MALT: keep macrophages and DCs in an immunoregulatory state
-still activate immune response
-don’t cause as much inflammation and damage
-less tissue damage, less repair needed
-reduced capacity for respiratory burst, cytokine storm, co-stimulation
What is the function of factors like IL-10, TGF-beta and Tregs
Limit inflammation in the mucosa that could damage the tissues
Examples of disregulated mucosal inflammatory response
Crohns disease, ulcerative collitis, inflammatory bowl disease, allergis, asthma, pulmonary fibrosis, COPD
How is tolerance against commensal microbes generated
Tregs
CD103+ DCs sample commensal antigens, DCs migrate to draining lymph node, secrete factors that polarize CD4+ T cells into Tregs
How are antigens sampled in the MALT
M cells capture and deliver them directly to MALT
What signals do lymphocytes use to migrate back to the mucosa after activation
Mucosal specific lymphocytes
express integrin ⍺4β7
⍺4β7 binds Mad-CAM-1 expressed
on mucosal-associated endothelial cells
Why are tissue specific responses important
Handle different exposure threats
Different tissues are affected by
different environmental exposures
* environmental pollution
* pathogens
* aging and metabolism
Tissue-specific compartmentalization allows for
specific changes to the immune system to handle these threats
How are antibodies transported across the epithelial layer
Pentameric IgM > poly IgR
Dimeric IgA > poly IgR
IgG > FcRn
What does it mean for COVID-19 to primarily be a mucosal disease? How does the expression pattern of its host receptors dictate the course of infection
It affects mucosal tissues such as the upper and lower respiratory tract
The receptor that covid-19 needs to bind to in order to enter the body is found in both the airway and the gut. This can cause covid to travel to the gut and in severe cases destroy the commensal bacteria which contributes to the severity of the disease and increases chances of secondary infections
