NFAT regulates neutrophil recruitment, systemic inflammation and T-cell dysfunction in abdominal sepsis.

The signaling mechanisms regulating neutrophil recruitment, systemic inflammation and T-cell dysfunction in polymicrobial sepsis are not clear. This study explored the potential involvement of the calcium/calcineurin-dependent transcription factor, nuclear factor of activated T-cells (NFAT) in abdominal sepsis. Cecal ligation and puncture (CLP) triggered NFAT-dependent transcriptional activity in the lung, spleen, liver and aorta in NFAT-luciferase reporter mice. Treatment with the NFAT inhibitor A-285222 prior to CLP completely prevented sepsis-induced NFAT activation in all these organs. Inhibition of NFAT activity reduced sepsis-induced formation of CXCL1, CXCL2 and CXCL5 chemokines and edema as well as neutrophil infiltration in the lung. Notably, NFAT inhibition efficiently reduced the CLP-evoked increases in HMBG1, IL-6 and CXCL5 levels in plasma. Moreover, administration of A-285222 restored sepsis-induced T-cell dysfunction, as evidenced by markedly decreased apoptosis and restored proliferative capacity of CD4 T-cells. Along these lines, treatment with A-285222 restored IFN-γ and IL-4 levels in the spleen, which were markedly reduced in septic mice. CLP-induced formation of regulatory T-cells (CD4(+)CD25(+)Foxp3(+)) in the spleen was also abolished in A-285222-treated animals. Altogether, these novel findings suggest that NFAT is a powerful regulator of pathological inflammation and T-cell immune dysfunction in abdominal sepsis. Thus, our data suggest that NFAT signaling might be a useful target to protect against respiratory failure and immunosuppression in patients with sepsis.