IBD IBD Pathophysiology 3

Question 1

Which molecule primarily mediates lymphocyte trafficking to the gut mucosa and is targeted by vedolizumab?

Accepted Answer

MAdCAM-1 / α4β7 integrin

Answer

Vedolizumab blocks the α4β7 integrin on lymphocytes from binding MAdCAM-1 on gut endothelium, selectively reducing intestinal lymphocyte homing.

Question 2

Dysbiosis in IBD most commonly involves a reduction in which beneficial bacterial genus?

Accepted Answer

Faecalibacterium

Answer

Faecalibacterium prausnitzii, a butyrate-producing commensal, is consistently reduced in IBD patients and has anti-inflammatory properties.

Question 3

Which prostaglandin pathway, when upregulated in IBD, contributes to mucosal inflammation and diarrhea?

Accepted Answer

COX-2 / PGE2 pathway

Answer

Upregulation of COX-2 leads to increased PGE2 production, which promotes vasodilation, mucus hypersecretion, and diarrhea in IBD.

Question 4

The JAK-STAT signaling pathway in IBD is targeted by which class of medications?

Accepted Answer

JAK inhibitors (e.g., tofacitinib)

Answer

JAK inhibitors like tofacitinib block JAK1/JAK3 enzymes, disrupting downstream STAT signaling that drives pro-inflammatory cytokine production in IBD.

Question 5

Paneth cells in the small intestine contribute to IBD pathogenesis primarily through which mechanism?

Accepted Answer

Secreting defensins and antimicrobial peptides that are impaired in Crohn's

Answer

Paneth cells secrete defensins (HD5, HD6) and other antimicrobial peptides; their dysfunction in Crohn's disease impairs mucosal defense against luminal bacteria.

IBD - Inflammatory Bowel Disease Practice Test

IBD - Inflammatory Bowel Disease Practice Test

IBD IBD Pathophysiology 3