Caspase-1 and interleukin-18 in children with post infectious bronchiolitis obliterans: a case-control study

The exact immunological mechanisms of post infectious bronchiolitis obliterans (PIBO) in childhood are not fully known. It has been shown that the inflammasome and IL-18 pathway play important roles in the pathogenesis of lung fibrosis. We aimed to investigate the role of caspase-1, IL-18, and IL-18 components in PIBO. From January to May 2020, children with PIBO, children with history of influenza infection without PIBO, and healthy children were asked to participate in the study in three pediatric pulmonology centers. Serum caspase-1, IL-18, IL-18BP, IL-18R, and INF-gamma levels were measured by ELISA and compared between the 3 groups. There were 21 children in the PIBO group, 16 children in the influenza group, and 39 children in the healthy control group. No differences in terms of age and gender between the 3 groups were found. IL-18 and IL-18BP levels were higher in the healthy control group (p = 0.018, p = 0.005, respectively). IL- 18R was higher in the PIBO group (p = 0.001) and caspase-1 was higher in the PIBO and influenza group than the healthy control group (p = 0.002). IFN-gamma levels did not differ between the 3 groups. IL-18BP/IL-18 was higher in the influenza group than the PIBO group and the healthy control group (p = 0.003). Conclusions: Caspase-1 level was increased in patients with PIBO which suggests that inflammasome activation may have a role in fibrosis; however, IL-18 level was found to be low. Mediators other than IL-18 may be involved in the inflammatory pathway in PIBO. Further immunological studies investigating inflammasome pathway are needed for PIBO with chronic inflammation.

Automated summary

This study aimed to investigate the role of caspase-1, IL-18, and IL-18 components in post infectious bronchiolitis obliterans (PIBO). The results showed that caspase-1 level was increased in PIBO patients, suggesting the involvement of inflammasome activation in fibrosis, but IL-18 level was found to be low.