Abstract
Influenza remains a significant threat to public health. In severe cases, excessive inflammation can lead to severe pneumonia or acute respiratory distress syndrome, contributing to patient morbidity and mortality. While antivirals can be effective if administered early, current anti-inflammatory drugs have limited success in treating severe cases. Therefore, discovering new anti-inflammatory agents to inhibit influenza-related inflammatory diseases is crucial. Herein, we screened a drug library with known targets using a human monocyte U937 infected with the influenza virus to identify novel anti-inflammatory agents. We also evaluated the anti-inflammatory effects of the hit compounds in an influenza mouse model. Our research revealed that JAK inhibitors exhibited a higher hit rate and more potent inhibition effect than inhibitors targeting other drug targets in vitro. Of the 22 JAK inhibitors tested, 15 exhibited robust anti-inflammatory activity against influenza virus infection in vitro. Subsequently, we evaluated the efficacy of 10 JAK inhibitors using an influenza mouse model and observed that seven provided protection ranging from 40% to 70% against lethal influenza virus infection. We selected oclacitinib as a representative compound for an extensive study to further investigate the in vivo therapeutic potential of JAK inhibitors for severe influenza-associated inflammation. Our results revealed that oclacitinib effectively suppressed neutrophil and macrophage infiltration, reduced pro-inflammatory cytokine production, and ultimately mitigated lung injury in mice infected with lethal influenza virus without impacting viral titer. These findings suggest that JAK inhibitors can modulate immune responses to influenza virus infection and may serve as potential treatments for influenza.IMPORTANCEAntivirals exhibit limited efficacy in treating severe influenza when not administered promptly during the infection. Current steroidal and nonsteroidal anti-inflammatory drugs demonstrate restricted effectiveness against severe influenza or are associated with significant side effects. Therefore, there is an urgent need for novel anti-inflammatory agents that possess high potency and minimal adverse reactions. In this study, 15 JAK inhibitors were identified through a screening process based on their anti-inflammatory activity against influenza virus infection in vitro. Remarkably, 7 of the 10 selected inhibitors exhibited protective effects against lethal influenza virus infection in mice, thereby highlighting the potential therapeutic value of JAK inhibitors for treating influenza.