Does low urinary sIgA predispose to urinary tract infection?

Area of Science:

• Immunology
• Urology
• Microbiology

Background:

• Secretory IgA (sIgA) is a crucial component of mucosal immunity.
• Recurrent urinary tract infections (UTIs) represent a significant health concern, particularly in women.
• Understanding the immune factors involved in UTI susceptibility is essential for developing effective prevention strategies.

Purpose of the Study:

• To investigate the role of urinary secretory IgA (sIgA) in the pathogenesis of recurrent urinary tract infections (UTIs).
• To compare urinary sIgA levels in healthy women, women with active UTI, and asymptomatic women with a history of UTI.
• To explore the relationship between urinary sIgA levels and the presence of antibody-coated bacteria.

Main Methods:

• Measurement of median urinary sIgA using the ELISA technique in unprocessed urine.
• Comparison of sIgA levels across different participant groups: healthy controls, acute UTI, asymptomatic UTI history, and individuals with nephrostomy and antibody-coated bacteria.
• Assessment of sIgA in nasal and salivary secretions in a subset of participants.

Main Results:

• Healthy women had a median urinary sIgA of 1.36 mg/liter.
• Significantly lower urinary sIgA levels were observed in women with UTI (median 0.16 mg/liter) and asymptomatic women with a history of UTI (median 0.52 mg/liter).
• Urinary sIgA was markedly elevated (median 14.4 mg/liter) in individuals with nephrostomy and antibody-coated bacteria, indicating localized immune response.

Conclusions:

• Locally synthesized urinary sIgA is reduced in individuals with recurrent UTIs, independent of current bacteriuria.
• Low urinary sIgA may be a predisposing factor for recurrent UTIs.
• UTI itself does not impair sIgA secretion, as evidenced by high levels in upper UTI cases.