TRPA1 Is Expressed In THP-1 Derived Macrophages And Regulates LPC-induced Inflammatory Responses

Transient receptor potential anchor 1(TRPA1)ion channel is a member of the transient receptor potential superfamily(TRP).TRPA1 is not only the main sense receptor of pain and temperature,but also can react to extracellular irritants and pressure.It plays an important role in physiological functions such as neuropathic pain,noxious cold and inflammatory response.Although TRPA1 is widely expressed in various tissues and organs,its expression and function have rarely been reported in lymphocytes.Lysophosphatidylcholine(LPC)is a crucial lipid molecule in mammalian.When atherosclerosis occurs,phospholipase A2(PLA2)in the body can catalyze the phosphatidylcholine(PC)on the cell membrane and oxidize lipoprotein into LPC.LPC is a significant pro-inflammatory and atherogenic lipid that promotes monocyte adhesion and the transformation of macrophages into foam cells.In endothelial cells,LPC can promote the production of mitochondrial reactive oxygen species(mtROS)on early atherosclerosis stage.In monocytes or macrophages,LPC regulates the secretion of inflammatory cytokines by activating inflammasomes.To date,the studies about LPC receptors have mainly focused on the G protein-coupled receptor(GPCRs)and TRP ion channel family,but the specific receptor and its downstream pathway of the receptor are still unclear.Although early studies have found that some GPCRs,such as GPR4,G2A,and GPR119,can participate in LPC-induced responses,none of them can prove a direct relationship between the LPC and GPCRs.TRP channel proteins,as receptors that can react to irritants,have been found to participate in physiological functions such as calcium influx induced by LPC and are potential targets of LPC receptor.The purpose of this study was to verify the functional expression level of TRPA1 in macrophages differentiated from human mononuclear cell line THP-1 and the role of TRPA1 in the regulation of LPC-induced inflammatory responses.In this study,real-time quantitative PCR(RT-qPCR)was used to detect the trpal mRNA transcription.Western blotting and immunofluorescence were used to detect the protein expression level of TRPA1 and the distribution of TRPA1 in THP-1 derived macrophages.In addition,calcium ion imaging was used to explore the function of TRPA1 in regulating the intracellular flow of calcium ions.We used chemical fluorescence detection to explore the role of TRPA1 in regulating LPC-induced mtROS generation and mitochondrial injury.TRPA1 was involved in the regulation of IL-1? secretion induced by LPC.TRPA1 was also involved in the regulation of LPC-induced cell pyroptosis by detecting the release of lactic dehydrogenase(LDH).Our results showed that TRPA1 was functionally expressed in THP-1 derived macrophages.TRPA1 involved in the regulation of calcium influx induced by LPC,mtROS generation,mitochondrial membrane potential deerease,the secretion of inflammatory factor IL-1? and the process of pyroptosis.These results demonstrated that TRPA1 has crucial physiological ftmotions in macrophages and is widely involved in the inflammatory response induced by LPC.Our research will provide references for further exploration of other functions of TRPA1 in macrophages,and also provide effective research evidence for its application in the development of drugs and antibodies targeting LPC receptors.