Effect of L-carnitine-mediated PLCγ1/calcineurin/NFAT signaling pathway on renal tubular epithelial cell apoptosis in microinflammatory microenvironment

The aim of this research was to explore the effect of L-Carnitine (LC)-mediated phospholipase Cγ1 (PLCγ1)/Calcineurin/nuclear factor of activated T cells (NFAT) signaling pathway on renal tubular epithelial cell apoptosis in microinflammatory microenvironment. HK-2 human renal tubular epithelial cell line was subsequently segregated into five groups: the normal control (NC) group, the TNF-α-induced microinflammation model group (TNF-α group), and three separate LC intervention groups that received sequential treatment with LC at gradient concentrations of 0.25, 0.50, and 1.00 mmol/L, respectively. The proliferative potential of cells was assessed by MTT assay. The cellular apoptotic levels were detected by flow cytometry and Hoechst 33342/PI dual staining. Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) techniques were performed to assay the relative mRNA transcription abundance of key proinflammatory mediators. Western blot analyses were carried out to measure and quantify the relative protein expression intensities. When contrasted with the NC group, the TNF-α group exhibited a marked decline in cellular proliferative activity and a dramatic increase in the apoptotic ratio within the cell population. Meanwhile, the mRNA expression abundances of CXCL5, CCL20, IL-1β, IL-6, and MCP-1, as well as the protein expression intensities of PLCγ1, Calcineurin, and NFAT, all underwent extreme upregulation ( P < 0.05). When benchmarked against the TNF-α group, pre-treating the cells with LC at the gradient concentrations of 0.25, 0.50, and 1.00 mmol/L triggered a distinct promotion in cellular proliferation rate and a prominent reduction in cellular apoptotic rate. Simultaneously, this pre-treatment approach exerted a potent suppressive impact on the mRNA expression of all the tested inflammation-associated genes and elicited a notable downregulation in the protein expression abundances of core regulatory molecules within the PLCγ1/Calcineurin/NFAT signaling axis ( P < 0.05). LC attenuated inflammatory cascade reactions and apoptotic events in renal tubular epithelial cell populations triggered by TNF-α. This cytoprotective action was realized through the suppression of PLCγ1/Calcineurin/NFAT signal transduction cascade activation, thereby exerting a putative renoprotective function in the pathological context of microinflammatory renal tissue damage.