Inhibiting TIRAP-mediated inflammatory signaling: A promising therapeutic strategy against sepsis

The timely therapeutic targeting of the dysregulated immune response in sepsis is essential to restore immune homeostasis and prevent progression to organ dysfunction. In this study, we investigated whether a combination therapy with an antibiotic exhibiting anti-inflammatory properties and the anti-inflammatory compound dorzolamide will improve the bacterial sepsis outcome. Using an in-silico approach, we screened a structure library of FDA-approved antibiotics to identify those that can interact with the Toll/interleukin-1 Receptor (TIR) domain-containing adaptor protein (TIRAP), a protein regulating proinflammatory cytokine production in immune cells. Our virtual screening identified a broad-spectrum antibiotic, levofloxacin, as a candidate. We subsequently employed the cecum slurry (CS) septic mouse model to validate the candidates in vivo, while monitoring survival of mice, tissue mRNA expression, cell morphology, cytokine levels, and other biochemical markers. The in vivo studies confirmed that the combination of levofloxacin and dorzolamide (LeDoz) increased the survival rate of septic mice. Hematoxylin and eosin (H&E) tissue staining, cytokine levels, as well as immunofluorescence dual staining and serum biomarkers, all showed the reestablishment of homeostatic conditions in the LeDoz-treated group of septic mice compared to untreated septic mice. In vitro analyses also confirmed the ability of LeDoz to attenuate TIRAP-mediated inflammatory signaling. Thus, the combination of levofloxacin and dorzolamide exhibits both an antibacterial effect and a strong potential for synergistically reducing chronic inflammation in the host by inhibiting the activation of TIRAP.