A Case-control Study of Urinary Tract Infection, 25‑hydroxyvitamin D Status and Associated Inflammatory and Regulatory Responses

Background: Vitamin D plays a key role in the modulation of numerous immune functions against infectious agents. We aimed to explore the association between serum 25‑hydroxyvitamin D (25[OH] D) levels and cytokine responses, along with hematological changes, in patients with urinary tract infection (UTI). Materials and Methods: Vitamin D level, cytokines (interferon [IFN]−γ, interleukin [IL]−4, IL−6, IL–10, IL−17A, tumor necrosis factor [TNF]−α, and transforming growth factor [TGF]−β), hematological indices (neutrophil-to-lymphocyte ratio [NLR], monocyte-to-lymphocyte ratio [MLR], neutrophil-to-monocyte ratio [NMR], platelet-to-lymphocyte ratio [PLR], and mean platelet volume [MPV]), C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) were evaluated in a case-control human study included 65 patients and 45 controls. Results: Among the enhanced cytokine levels in patients, the cytokines IFN-γ, IL-17A, and IL-10 had a significant association with 25(OH)D, but not IL-6, TNF-α, and TGF-β. The IL-4 levels remained unchanged. By comparing hematological indices, we found the association of increased NLR and MLR with 25(OH)D and the cytokines IFN-γ and IL-17A, along with a decrease in the PLR without showing such an association. The NMR did not show any significant difference. The platelet count showed an association with IL-6, IL-17A, and TGF-β, but the association of MPV with 25(OH)D was significant. The ESR results exhibited statistically non-significant differences. CRP elevation was directly associated with IL-6 and IL-17A, but not with 25(OH)D. Conclusion: 25(OH)D-mediated inflammatory cytokine milieu might alter the proportion and function of peripheral blood cells in a regulated manner to support bacterial clearance which needs further studies to be validated.