intravascular adhesion and recruitment of neutrophils in response to cxcl1 depends on their trpc6 channels

Here we report a novel role for trpc6, a member of the transient receptor potential (trpc) channel family, in the cxcl1-dependent recruitment of murine neutrophil granulocytes. representing a central element of the innate immune system, neutrophils are recruited from the blood stream to a site of inflammation. the recruitment process follows a well-defined sequence of events including adhesion to the blood vessel walls, migration, and chemotaxis to reach the inflammatory focus. a common feature of the underlying signaling pathways is the utilization of ca2+ ions as intracellular second messengers. however, the required ca2+ influx channels are not yet fully characterized. we used wt and trpc6−/− neutrophils for in vitro and trpc6−/− chimeric mice (wt mice with wt or trpc6−/− bone marrow cells) for in vivo studies. after renal ischemia and reperfusion injury, trpc6−/− chimeric mice had an attenuated trpc6−/− neutrophil recruitment and a better outcome as judged from the reduced increase in the plasma creatinine concentration. in the cremaster model cxcl1-induced neutrophil adhesion, arrest and transmigration were also decreased in chimeric mice with trpc6−/− neutrophils. using atomic force microscopy and microfluidics, we could attribute the recruitment defect of trpc6−/− neutrophils to the impact of the channel on adhesion to endothelial cells. mechanistically, trpc6−/− neutrophils exhibited lower ca2+ transients during the initial adhesion leading to diminished rap1 and β2 integrin activation and thereby reduced icam-1 binding. in summary, our study reveals that trpc6 channels in neutrophils are crucial signaling modules in their recruitment from the blood stream in response to cxcl1. neutrophil trpc6 channels are crucial for cxcl1-triggered activation of integrins during the initial steps of neutrophil recruitment.