Hydroxyproline increases inflammation and Uropathogenic E. coli (UPEC) infection in female rats

Area of Science:

• Urology
• Immunology
• Microbiology

Background:

• Calcium oxalate (CaOx) kidney stones are potentially linked to urinary tract infections (UTIs).
• The underlying mechanisms connecting CaOx stones and UTIs remain unclear.
• Understanding this association is crucial for patient management.

Purpose of the Study:

• To investigate the impact of dietary oxalate on immune responses.
• To determine oxalate's role in the development of Uropathogenic E. coli (UPEC) induced UTIs in vivo.
• To elucidate potential mechanisms linking oxalate and UTI pathogenesis.

Main Methods:

• Female Sprague-Dawley rats were fed a control or Hydroxy-L-proline (HLP) diet to increase oxalate levels.
• Rats were infected transurethrally with UPEC.
• Urinary oxalate, renal CaOx deposition, inflammatory markers (cytokines, macrophages), and bacterial loads were quantified.

Main Results:

• HLP-fed rats exhibited significantly higher urinary oxalate and renal CaOx deposition.
• Increased pro-inflammatory macrophages and cytokines were observed in HLP-fed, UPEC-infected rats.
• HLP diet led to elevated bacterial loads and reduced anti-inflammatory markers in HLP-fed rats.

Conclusions:

• Dietary oxalate promotes UTI development by enhancing inflammation and bacterial persistence.
• Oxalate may play a significant role in the pathogenesis of UTIs, particularly in individuals prone to kidney stones.
• These findings highlight a novel mechanism connecting oxalate metabolism and urinary tract infections.