Gut Immunity, Nutrition, and adverse food reactions Flashcards
How is homeostasis in the gut mucosa preserved?
Homeostasis is preserved by secretory IgA-dependent immune exclusion of Ags and by the suppression of proinflammatory responses by induced oral tolerance
Describe the process of oral tolerance.
- Ags are captured by Peyer’s patches in the lamina propria and carried to mesenteric LN by DC.
- In the LN, DC stimulate expansion of induced Treg cells by a mehcnaism dependent on TGF-beta, retinoic acid and indoleamine -2, 3 - diooxygenase (IDO)
- DC induce IgA-secreting plasma cells although RA-dependent mechanism.
- Gut-homing iTregs are expanded in the lamina propria by the IL-10-expressing macrophages.
- These iTregs can then suppress systemic immune responses, including allergic sensitization, in an Ag-specifc manner.
Which vitamins suppress inflammation?
Vit D, A, and folate, and long chain fatty acids
What kind of diet promote inflammation?
high-fat diet and medium chain triglycerides
The gut microbiota is able to suppress allergic immune response by inducing what cells?
Treg cells, suppressing basophils and mast cells. iTregs also suppress allergic effector cells.
What cells provides the effector mechanism of allergy?
IgE, basophils, and mast cells
True or false, undernutrition is associated with defects in the innate and adaptive immunity.
True
IgE mediated reaction is what kind of hypersensitivity?
Type I hypersensitivity
Type III hypersensitivity is mediated by what Ig?
IgG and IgM immune complex.
Cell-mediated reaction are what type of hypersensitivity?
Type IV
What cell is critical for both local and systemic manifestation of food allergy?
Mast cells
GI manifestation of food allergy dependent on which cytokines?
IL4, IL9, IL13
What mediates the local acute GI response like diarhea to allergen exposure?
PAF (Platelet activating factor) and serotonin
Food allergy occurs in two phase, what are they?
1 Sensitization - the body makes ab against the allergan
2. Allergic reaction - exposure to that same allergen will elicit immune response
In food-induced anaphylaxis, mast cells are activated by what immunoglobulin and what does it cross link with?
Mast cells is activated by IgE and cross-links to FceRI. IT can also occur via IgG-induced activation of Macrophages
Which mediators of mast cells are responsible for the symptoms seen in food allergy?
histamine and PAF which increase vascular permeability and smooth muscle contractility
The complement system exacerbates the symtomps of food allergy and anaphaxis. Which components of the complement system are exudated and what are those components activated by?
Histamine causes vascular permeability and then C3 and C5 comes out. Tryptase released from aciated mast cells act on C3 and C5 to locally generated C3a and C5a.
which HLA molecules are the main genetic predisposing factor for celiac disease?
HLA-DQ2 and DQ8
Which molecules play a key role in orchestrating an adaptive immune response against gluten peptides?
HLA-DQ2 and HLADQ8
In celiac disease, autoantibodies are formed against which enzyme?
tissue transglutaminase 2
Celiac disease is what kind of hypersensitivity?
type IV.
Gluten is proline-rich protein that is poorly digested in small intestinal tract to lack of what enzyme?
prolylendopeptidases.
What two amino acids are abundant in gluten?
Proline and glutamine
How does gluten act as antigen?
peptides with a specific spacing of proline and glutamine acid bind to HLA class II on APCs. Majority of CD patients express HLADW2.5 heterodimer.
