Tacrolimus increases the expression level of the chemokine receptor CXCR2 to promote renal fibrosis progression.

Tacrolimus is one of the most used and effective immunosuppressive agents currently available in the clinic; however, its use is limited by nephrotoxicity, which is the main secondary effect of this drug. The mechanisms underlying tacrolimus‑induced nephrotoxicity remain unknown. The present study aimed to investigate the mechanism underlying tacrolimus‑induced nephrotoxicity and to identify novel potential targets. Masson staining, Sirius red staining and periodic acid‑silver methenamine staining were used to observe kidney pathological changes. Immunohistochemical and immunofluorescent analyses were performed to examine the expression levels of vimentin, E‑cadherin and α‑smooth muscle actin (α‑SMA). Transcriptomics and bioinformatics analyses were performed to investigate the nephrotoxicity mechanism induced by tacrolimus using RNA‑sequencing, differentially expressed genes identification and annotation, and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. The present results demonstrated that compared with the normal control group, the tacrolimus nephrotoxicity group exhibited severe renal fibrosis (P<0.05), upregulated vimentin (P<0.01), downregulated E‑cadherin (P<0.05) and upregulated α‑SMA (P<0.01). Transcriptomics and bioinformatics analyses identified the pathway 'cytokine‑cytokine receptor interaction' as the most significantly enriched (P<0.05). Moreover, KEGG pathway enrichment analysis identified that tacrolimus increased the expression levels of chemokine (C‑X‑C) motif ligand (CXCL)1, CXCL2 and CXCL3 and the chemokine receptor C‑X‑C chemokine receptor type 2 (CXCR2). Collectively, the present study suggested that tacrolimus increases the level of chemokine receptor CXCR2 to promote renal fibrosis progression, which is one of the potential mechanisms underlying tacrolimus‑induced nephrotoxicity.