Cinnamaldehyde Attenuates Hyperuricemia-Associated Renal Injury by Modulating Urate Transporters and AIF1- and CMPK2/NLRP3-Related Inflammatory Signaling

Background: Hyperuricemia is a well-established risk factor for both chronic kidney disease and gout. Currently available urate-lowering drugs, however, are frequently compromised by hepatorenal toxicity and gastrointestinal adverse effects. Cinnamaldehyde, the principal bioactive constituent of the traditional Chinese medicine cinnamon, has documented renoprotective properties, yet its integrated effects on hyperuricemia-associated renal injury remain incompletely defined. Objectives: This study investigated the therapeutic effects of cinnamaldehyde on hyperuricemia and explored the molecular mechanisms involved. Materials and Methods: An in vivo hyperuricemia model was established in KM mice by co-administration of potassium oxonate and hypoxanthine for 14 consecutive days, and an in vitro injury model was generated by exposing HK-2 human renal tubular epithelial cells to uric acid. For the in vivo study, mice were divided into five groups (control, model, febuxostat, low-dose CA, and high-dose CA; n = 9 per group) and were treated by oral gavage. Serum biochemical indices, renal and intestinal histopathology, inflammatory cytokines, renal urate transporter proteins (OAT1, OCT2, ABCG2, and SLC2A9), and components related to AIF1 and CMPK2/NLRP3 inflammasome signaling (ASC, caspase-1, IL-18, and IL-1β) were examined. Western blotting, qPCR, immunofluorescence, apoptosis analysis, mitochondrial membrane potential assessment, transmission electron microscopy, siRNA-mediated knockdown, and 16S rRNA gene sequencing were used to characterize the relevant mechanisms. Results: CA reduced serum uric acid (p ≤ 0.001 vs. model), creatinine (p ≤ 0.01 vs. model), and blood urea nitrogen (p ≤ 0.01 vs. model), alleviated renal and intestinal histopathological injury, and decreased circulating and renal inflammatory cytokines. Cinnamaldehyde increased ABCG2, OAT1, and OCT2 protein expression and reduced SLC2A9 expression (all p ≤ 0.05 vs. model). In vivo and in vitro, cinnamaldehyde suppressed AIF1- and CMPK2/NLRP3-related inflammatory proteins, reduced uric acid-induced apoptosis, and preserved mitochondrial membrane potential and ultrastructure. Fecal 16S rRNA sequencing suggested changes in selected microbial taxa, although alpha-diversity and BrayCurtis-based PERMANOVA/ANOSIM analyses did not demonstrate significant global community separation. Conclusions: These findings suggest that CA alleviates hyperuricemia-associated renal injury by regulating renal urate transporters, attenuating AIF1- and CMPK2/NLRP3-related inflammatory signaling, accompanied by compositional shifts in selected gut microbial taxa that warrant further mechanistic investigation. The study provides experimental support for further evaluation of cinnamaldehyde as a multi-target candidate for hyperuricemia-related renal injury.