Plasma Zinc Levels in Patients with Diabetic Nephropathy: Is there a Relationship with NLRP3 Inflammasome Activation and Renal Prognosis?

Zinc is an essential trace element, and impaired zinc homeostasis may be associated with inflammation in patients with diabetic nephropathy (DN). We investigated the influence of zinc level on nod-like receptor nucleotide-binding domain and leucine-rich repeat pyrin-3 domain (NLRP3) inflammasome expression and renal prognosis in patients with DN. We recruited 90 patients definitively diagnosed with DN by renal biopsy and 40 healthy controls. Zinc, NLRP3, interleukin (IL)-1β, and IL-18 levels were detected in blood samples, and the correlations between these parameters were assessed. Receiver operating characteristic (ROC) curve and decision curve analysis (DCA) evaluated the predictive value of zinc and the NLRP3 inflammasome for DN. Furthermore, patients with DN were divided into low- and normal-zinc groups to observe differences in clinical indicators and identify expression of inflammatory-related factors in renal tissue. Kaplan–Meier survival curves predicted the impact of zinc levels on renal prognosis. We found that the plasma zinc concentration in patients with DN was lower, while NLRP3, IL-1β, and IL-18 levels were higher than were those in patients without DN (P < 0.05). Zinc level was negatively correlated with NLRP3, IL-1β, and IL-18 levels (P < 0.01). Zinc and the NLRP3 inflammasome were predictive of DN, but their combination improved the diagnostic value. The DCA curve demonstrated a good positive net benefit in the combined model. Compared to patients with low zinc levels, patients with normal zinc levels had lower expression of NLRP3 inflammasome and a better prognosis. Zinc has a protective effect on DN and may affect NLRP3 inflammasome activation.