L10 Microflora and Immune System

Question 1

Immune Barriers of the GIT?

Answer 1

Saliva

• Lysozymes
• Nucleases
• IgA

Epithelial Barriers: Apical Tight Junctions (Necessitates transporters to move nutrients transcellular)

Stomach

• HCl=> H. Pylori
• Peptidases

Question 2

Beneficial Functions of Microbes in the GIT?

Answer 2

Protective:

• Pathogen Displacement/Nutrient Competition
• Production of Antimicrobial Factors

Structural:

• Barrier Fortification
• Induction of IGA
• Apical Membrane Tightening

Metabolic:

• Amino Acid Synthesis
• Syhtesized Vitamins (Vit K, Biotin, Folate)
• Iron Absorption

Question 3

Organized patches of lymphoid aggregates in ilium (high prevalence of M Cells) that play important role in responding to food/bacteria in the intestine?

Answer 3

Peyer’s Patches

Question 4

Predominant Immune response in the Gut?

What do they differentiate to/protect against?

Answer 4

T Helper Cells 2 differentiate in presence of IL4 => B Cells

Defense against parasitic worms, also associated w/ Allergy,Asthma

Question 5

Cells responsible for Major Phagocytosis?

Answer 5

Macrophages

Question 6

Cells responsible for Antigen Presenting with the capacity to reach out between tight junctions of epithelial junctions to grab antigenic material and present to cells in mucosa?

Answer 6

Dendritic Cells

Question 7

Phagocytes and first responders to Infection?

Answer 7

Neutrophils

Question 8

Protective Secretions of Goblet vs. Paneth cells in Stomach?

Answer 8

Goblet Cells: Mucins, Lysozyme

Paneth Cells (crypts of Lieberkühn): Defensins, IgA

Question 9

M- Cells (aka. Microfold cells)

Location?

MOA?

Answer 9

M-Cells are associated w/ Payer’s Patch

Question 10

Immune Tolerance versus. Oral Tolerance?

Answer 10

Tolerance to Comensal Microbiota is affiliated with M Cells in Intestines

Tolerance to Ingested Soluble Antigens associated with Dendritic Cells (Intestinal or Systemic)

Question 11

Nucleotide Binding and Oligomerization Domain (NOD) Like- Receptors (NLRS) versus Toll-Like Receptors?

Answer 11

Nucleotide Binding and Oligomerization Domain (NOD) Like-Receptors (NLRS): Cytoplasmic Receptors activate intracellular cascade (Recognize PAMPS)

• ASSOCIATED with Inflammatory Bowel Disease

Toll-Like Receptors: Detects LPS from bacteria on cell membrane (unlike NLRS that is cytoplasmic)

Question 12

Nucleotide Binding and Oligomerization Domain (NOD) Like-Receptors (NLRS) vs. Toll-Like Receptors?

What do they crosstalk to activate?

Answer 12

Nucleotide Binding and Oligomerization Domain (NOD) Like-Receptors (NLRS): Cytoplasmic Receptors activate intracellular cascade (Recognize PAMPS)

• ASSOCIATED with Inflammatory Bowel Disease

Toll-Like Receptors: Detects LPS from bacteria on cell membrane (unlike NLRS that is cytoplasmic)

TLR & NLR crosstalk to produce active pro-inflammatory cytokine IL1Beta