RESUMO
Viral-bacterial coinfections, such as with influenza A virus and Streptococcus pneumoniae (S.p.), are known to cause severe pneumonia. It is well known that the host response has an important role in disease. Interleukin-1ß (IL-1ß) is an important immune signaling cytokine responsible for inflammation and has been previously shown to contribute to disease severity in numerous infections. Other studies in mice indicate that IL-1ß levels are dramatically elevated during IAV-S.p. coinfection. However, the regulation of IL-1ß during coinfection is unknown. Here, we report the NLRP3 inflammasome is the major inflammasome regulating IL-1ß activation during coinfection. Furthermore, elevated IL-1ß mRNA expression is due to enhanced TLR2-MYD88 signaling, which increases the amount of pro-IL-1ß substrate for the inflammasome to process. Finally, NLRP3 and high IL-1ß levels were associated with increased bacterial load in the brain. Our results show the NLRP3 inflammasome is not protective during IAV-S.p. coinfection.