Question

Ig A nephropathy seen in which intestinal infection?

• A. Shigella
• B. E. Coli
• C. Pseudomonas
• D. Enterococci

Hint:

IgA Nephropathy vs. PSGN:
- IgA Nephropathy: Synpharyngitic Syngastrointestinal hematuria (develops within 24--48 hours of infection), normal C3 levels, mesangial IgA deposition.
- PSGN: Post-infectious latency (1--2 weeks post-pharyngitis, 3--6 weeks post-impetigo), low serum C3 levels, subepithelial "humps".

Answer 1

The Correct Option is B

Concept:
Immunoglobulin A (IgA) Nephropathy (Berger disease) is the most common primary glomerulonephritis worldwide.
The classic pathophysiology involves aberrant mucosal immunity and galactose-deficient IgA1 (Gd-IgA1) synthesis triggered by mucosal infections of the upper respiratory or gastrointestinal tract, leading to immune complex formation and mesangial deposition.
Explanation:
• The fundamental "multi-hit hypothesis" of IgA nephropathy involves mucosal hyper-reactivity to microbial pathogens colonizing the gut-associated lymphoid tissue (GALT) and nasopharynx-associated lymphoid tissue (NALT).

• Enteric mucosal exposure to common Gram-negative intestinal commensals and pathogens, particularly Escherichia coli strains, triggers toll-like receptor (TLR) signaling and excessive production of poorly galactosylated secretory IgA1.

• E. coli outer membrane proteins and lipopolysaccharides have been shown to act as mucosal antigens that stimulate IgA-secreting plasma cells in the intestinal lamina propria, contributing to circulating anti-glycan autoantibodies and subsequent nephritogenic immune-complex deposition in the renal mesangium.

• Clinically, synpharyngitic or syngastrointestinal gross hematuria classically appears within 24 to 48 hours following a respiratory or gastrointestinal infection (unlike post-streptococcal glomerulonephritis, which has a latent period of 1 to 3 weeks).

• Renal biopsy characteristically demonstrates mesangial proliferation with dominant or co-dominant mesangial IgA and C3 deposition on immunofluorescence.
Final Answer:
Enteric infection and mucosal antigenic stimulation by Escherichia coli in the gut-associated lymphoid tissue are closely associated with the pathogenesis and flare-ups of IgA nephropathy.