Lung Diseases

Interleukin-1β exacerbates disease and is a potential therapeutic target to reduce pulmonary inflammation during severe influenza A virus infection

Hyperinflammatory responses including the production of NLRP3-dependent interleukin (IL)-1β is a characteristic feature of severe and fatal influenza A virus (IAV) infections. The NLRP3 inflammasome has been shown to play a temporal role during severe IAV immune responses, with early protective and later detrimental responses. However, the specific contribution of IL-1β in modulating IAV disease in vivo is currently not well defined. Here, we identified that activation of NLRP3-dependent IL-1β responses occurs rapidly following HKx31 H3N2 infection, prior to the onset of severe IAV disease. Mature IL-1β was detectable in vivo in both hemopoietic and nonhemopoietic cells. Significantly, therapeutic inhibition of IL-1β in the airways with intranasal anti-IL-1β antibody treatment from day 3 postinfection, corresponding to the onset of clinical signs of disease, significantly prolonged survival and reduced inflammation in the airways. Importantly, early targeting of IL-1β from day 1 postinfection also improved survival. Together, these studies specifically define a role for IL-1β in contributing to the development of hyperinflammation and disease and indicate that targeting IL-1β is a potential therapeutic strategy for severe IAV infections.

Repurposing drugs targeting the P2X7 receptor to limit hyperinflammation and disease during influenza virus infection

Background and Purpose

Severe influenza A virus (IAV) infections are associated with damaging hyperinflammation that can be fatal. There is an urgent need to identify new therapeutic agents to treat severe and pathogenic IAV infections. Repurposing of drugs with an existing and studied pharmacokinetic and safety profile is a highly attractive potential strategy. We have previously demonstrated that the NLRP3 inflammasome plays time‐dependent roles during severe IAV infection with early protective responses and later dysregulation leading to excessive inflammation, contributing to disease severity.

Experimental Approach

We tested two existing drugs, probenecid and AZ11645373, to target P2X7 receptor signalling and dampen NLRP3 inflammasome responses during severe IAV infection. In vitro, the drugs were assessed for their ability to limit NLRP3 inflammasome‐dependent IL‐1β secretion in macrophage cultures. In vivo, their effects were assessed on hyperinflammation and disease during severe IAV infection in C57BL/6 mice.

Key Results

Treatment of macrophages with probenecid or AZ11645373 in vitro diminished NLRP3 inflammasome‐dependent IL‐1β secretion. Intranasal therapeutic treatment of mice displaying severe influenza disease with probenecid or AZ11645373 reduced pro‐inflammatory cytokine production, cellular infiltrates in the lung, and provided protection against disease. Importantly, these drugs could be administered at either early or late stage of disease and provide therapeutic efficacy.

Conclusions and Implications

Our study demonstrates that the anti‐inflammatory drugs probenecid and AZ11645373, which have documented pharmacokinetics and safety profiles in humans, are effective at dampening hyperinflammation and severe influenza disease providing potentially new therapeutic strategies for treating severe or pathogenic IAV infections.