Atherosclerosis (AS) is a chronic inflammatory disease, which has a complex interplay between altered immune metabolism and oxidative stress. Therefore, we aimed to determine the oxidative stress and immune‐related biomarkers in AS. Differential gene expression analyses are based on the GSE100927 dataset in the Gene Expression Omnibus (GEO), and 389 oxidative stress (OS) genes are identified based on gene set enrichment analysis (GSEA). We identified 74 differentially expressed genes related to oxidative stress (DEOSGs). “CIBERSORT” and “WGCNA” R Packages were used to compare the differences in immune infiltration levels between AS and control samples. The DEOSGs (N = 74) were intersected with the key module’s genes of WGCNA (N = 972), and 27 differentially expressed immune‐related oxidative stress genes (DEIOSGs) were obtained. To identify the pivotal genes, a protein‐protein interaction (PPI) network was constructed using the STRING database and the Cytoscape software. MMP9, ALOX5, NCF2, NCF, and NCF4 were identified as diagnostic markers of AS, and we validated them in the GSE57691 dataset. The expression levels of the five diagnostic genes were significantly highly expressed in the AS group. Correlation analysis and single‐cell analysis revealed that five diagnostic genes were mainly correlated with macrophages M1. We, respectively, intersected differentially expressed genes (DEGs) with ferroptosis gene set, necroptosis gene set, and pyroptosis gene set. The findings suggested that ALOX5 and NCF2 were differentially expressed genes of ferroptosis. High expression of five hub genes in RAW264.7 macrophages were confirmed by PCR. High ALOX5 and NCF2 expression levels in plaque tissues were confirmed by immunohistochemistry (IHC) and western blotting. Our study identified that MMP9, ALOX5, NCF2, NCF1, and NCF4 were diagnostic genes of AS and associated with oxidative stress. ALOX5 and NCF2 may be involved in the formation of the necrotic core in AS by regulating macrophage ferroptosis.

Contrast-induced acute kidney injury (CIAKI) is a common complication with limited treatments. Intermedin (IMD), a peptide belonging to the calcitonin gene-related peptide family, promotes vasodilation and endothelial stability, but its role in mitigating CIAKI remains unexplored. This study investigates the protective effects of IMD in CIAKI, focusing on its mechanisms, particularly the cAMP/Rac1 signaling pathway. Human umbilical vein endothelial cells (HUVECs) were treated with iohexol to simulate kidney injury in vitro. The protective effects of IMD were assessed using CCK8 assay, flow cytometry, ELISA, and Western blotting. A CIAKI rat model was utilized to evaluate renal peritubular capillary endothelial cell injury and renal function through histopathology, immunohistochemistry, immunofluorescence, Western blotting, and transmission electron microscopy. In vitro, IMD significantly enhanced HUVEC viability and mitigated iohexol-induced toxicity by preserving intercellular adhesion junctions and activating the cAMP/Rac1 pathway, with Rac1 inhibition attenuating these protective effects. In vivo, CIAKI caused severe damage to peritubular capillary endothelial cell junctions, impairing renal function. IMD treatment markedly improved renal function, an effect negated by Rac1 inhibition. IMD protects against renal injury in CIAKI by activating the cAMP/Rac1 pathway, preserving peritubular capillary endothelial integrity and alleviating acute renal injury from contrast media. These findings suggest that IMD has therapeutic potential in CIAKI and highlight the cAMP/Rac1 pathway as a promising target for preventing contrast-induced acute kidney injury in at-risk patients, ultimately improving clinical outcomes.

Background: Contrast-induced acute kidney injury (CIAKI) is a common complication in hospital-acquired renal conditions, yet its pathogenesis remains unclear and effective treatments are limited. Intermedin (IMD), a peptide related to the calcitonin gene, exhibits vasodilatory and endothelial barrier-stabilizing effects via the calcitonin receptor-like receptor (CLR). However, the potential of IMD in mitigating CIAKI has not been thoroughly investigated. Aims: This study aimed to delineate the protective role of IMD in CIAKI through both in vitro and in vivo models, with a particular focus on elucidating the underlying mechanisms, specifically the cAMP/Rac1 signaling pathway. Methods: Human umbilical vein endothelial cells (HUVECs) were treated with iohexol to simulate kidney injury in vitro. The protective effects of IMD were evaluated using the CCK8 assay, flow cytometry, ELISA, and western blotting. A CIAKI rat model was developed to assess renal peritubular capillary endothelial cell injury and renal function using a range of techniques, including histopathology, immunohistochemistry, immunofluorescence, western blotting, and transmission electron microscopy. Results: In vitro, IMD significantly enhanced HUVEC viability and mitigated iohexol-induced toxicity by preserving intercellular adhesion junctions and activating the cAMP/Rac1 pathway. The protective effects of IMD were attenuated by Rac1 inhibition. In vivo, CIAKI caused considerable damage to peritubular capillary endothelial cell junctions, leading to impaired renal function. IMD treatment markedly improved renal function, an effect that was abolished by Rac1 inhibition. Conclusion: IMD protects against renal injury in CIAKI by activating the cAMP/Rac1 pathway, thereby preserving the integrity of peritubular capillary endothelial cells and mitigating acute renal injury induced by contrast media. These findings underscore the therapeutic potential of IMD in CIAKI and emphasize the critical role of the cAMP/Rac1 pathway in renal protection.