Impact of zinc-mediated nutritional immunity on uropathogenic Escherichia coli (UPEC) virulence gene expression in female recurrent UTI patients

Abstract

This study investigates the influence of zinc-mediated nutritional immunity on virulence gene expression in Uropathogenic Escherichia coli (UPEC) among female patients with recurrent urinary tract infections (UTIs). Fifty women with microbiologically confirmed UTIs were enrolled in a controlled interventional design and divided equally into zinc-supplemented and control groups. The intervention group received 40 mg elemental zinc daily for three days. Urine samples collected pre- and post-intervention were analyzed for bacterial gene expression (znuA, hlyA, fimH) using RT-qPCR, and cytokine levels (IL-6, IL-8) via ELISA. Urinary zinc levels were also quantified. The results revealed a significant increase in urinary zinc concentration following supplementation (p = 1.35 × 10⁻⁹), accompanied by marked downregulation of znuA and hlyA expression (fold changes of 0.42 and 0.53, respectively), but not fimH. Statistically significant post-intervention differences in ΔCt values for znuA and hlyA were observed only in the zinc group (p < 0.001), indicating gene-specific suppression due to zinc availability. Additionally, urinary IL-6 and IL-8 levels were significantly lower in the zinc-supplemented group (p = 1.63 × 10⁻⁵ and 4.33 × 10⁻¹², respectively), suggesting an anti-inflammatory effect. Multivariate linear regression further identified zinc supplementation as an independent predictor of reduced IL-6 levels and increased znuA ΔCt values, while age and BMI had no significant effect on these outcomes. These findings support zinc's role in modulating both bacterial virulence and host inflammatory responses, highlighting its potential as an adjunct therapy for recurrent UTIs. By disrupting critical virulence mechanisms and reducing urinary cytokine levels, zinc supplementation may reduce the pathogenicity of UPEC and improve host outcomes. This study provides molecular and clinical insights that support dietary zinc modulation as a promising non-antibiotic strategy in managing recurrent UTIs.