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α-Intercalated cells defend the urinary system from bacterial infection
The Journal of Clinical Investigation
|June 18, 2014
Summary
Kidney α-intercalated cells (A-ICs) defend against urinary infections by acidifying urine and releasing lipocalin 2 (LCN2). This study reveals A-ICs are crucial sentinels and effectors in combating bacterial pathogens.
Area of Science:
- Nephrology
- Immunology
- Microbiology
Background:
- α-Intercalated cells (A-ICs) in the kidney collecting duct are vital for maintaining acid-base balance.
- Their role in host defense against urinary tract infections was previously unexplored.
Purpose of the Study:
- To investigate the function of A-ICs as sentinels and effectors in combating urinary tract infections.
- To elucidate the mechanisms by which A-ICs contribute to urinary defense.
Main Methods:
- Utilized a murine model of urinary tract infection with uropathogenic E. coli.
- Assessed A-IC binding, urine acidification, and lipocalin 2 (LCN2) secretion.
- Investigated the role of Toll-like receptor 4 (TLR4) in A-IC-mediated responses.
- Examined bacterial clearance in A-IC-deficient mice.
Main Results:
- A-ICs bind uropathogenic E. coli and respond by acidifying urine and secreting LCN2 (NGAL).
- A-IC-dependent LCN2 secretion requires TLR4 signaling.
- Urinary LCN2 is essential for controlling infection via iron sequestration, even in acidic urine.
- Mice lacking A-ICs showed reduced urinary LCN2 and acidification, impairing bacterial clearance.
Conclusions:
- A-ICs are critical for urinary defense against pathogenic bacteria, acting as both sentinels and effectors.
- A-ICs contribute to combating infections like cystitis and pyelonephritis by delivering bacteriostatic agents.
- The findings highlight a novel role for A-ICs beyond acid-base homeostasis in innate immunity.
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