KLF15 attenuates lipopolysaccharide-induced apoptosis and inflammatory response in renal tubular epithelial cells via PPARδ

Abstract

Abstract Background The kidney is the most commonly affected organ in sepsis patients, and Kruppel-like transcription factor 15 (KLF15) has a kidney-protective effect and is highly enriched in the kidneys. This study aims to explore the role of KLF15 in sepsis-related acute kidney injury. Methods A septic injury model in HK2 cells was established through the administration of lipopolysaccharide (LPS), followed by the transfection of an overexpression plasmid for KLF15. Cell viability was assessed using CCK-8 assay, and apoptosis was measured via flow cytometry. The levels of inflammatory cytokines were detected using ELISA, and Western blot (WB) assay was employed to assess the expression of KLF15, PPARδ, as well as inflammatory and apoptosis-related proteins. The interaction between KLF15 and PPARδ was confirmed through the utilization of online databases and immunoprecipitation (IP) experiments. The mechanism was further validated using PPARδ agonists and small interfering RNA (siRNA). Results LPS-induced HK2 cells showed down-regulated expression of KLF15 and PPARδ, along with decreased viability, accompanied by increased levels of apoptosis, TNFα, IL-1β, and IL-6. Additionally, LPS upregulated the expression of Bax, cytoplasmic cytochrome C [Cytc (cyt)], Cox-2, and p-NF-κB-p65 in HK2 cells, while simultaneously downregulating the expression of Bcl2 and mitochondrial cytochrome c [Cytc (mit)]. IP experiment revealed a possible interaction between KLF15 and PPARδ in HK2 cells. Ov-KLF15, Ov-PPARδ or administration of PPARδ agonists effectively alleviated the aforementioned alterations induced by LPS. However, interference with PPARδ significantly attenuated the protective effect of Ov-KLF15 on HK2 cells. Conclusion KLF15 attenuates LPS-induced apoptosis and inflammatory responses in HK2 cells via PPARδ.