E3 Ubiquitin Ligase NKLAM/RNF19b Regulates Inflammatory Cytokine Production in a Sendai Virus Pneumonia Model

Abstract Recent studies have shown that E3 ubiquitin ligases are important mediators of the innate immune response. Studies from our laboratory have defined a role for the ubiquitin ligase natural killer lytic-associated molecule (NKLAM) in mouse and human innate immunity. Here, we present novel data describing a role for NKLAM in regulating the immune response to Sendai virus (SeV)-induced respiratory infection in mice. We found that NKLAM−/− mice demonstrated significantly less weight loss than wild type mice during SeV infection. Immunohistochemical analysis showed that the lungs of NKLAM−/− mice had less perivascular and peribronchial leukocyte accumulation than wild type mice. Using flow cytometry, we found the lungs of NKLAM−/− mice contained a lower percentage of neutrophils, macrophages and NK cells than wild type mice post-infection. The expression of several key pro-inflammatory cytokines/chemokines that are transcriptionally regulated by STAT1 and/or NFκB such as IL-6, IFNγ and MCP-1 was decreased in NKLAM−/− mice. Consistent with these findings, STAT1 and NFκB p65 phosphorylation were significantly lower in NKLAM−/− mice than in wild type mice. Collectively, our results suggest that NKLAM plays a role in orchestrating the innate immune response to SeV by regulating the expression of pro-inflammatory cytokines.