Mice deficient in NKLAM have attenuated inflammatory cytokine production in a Sendai virus pneumonia model

Recent studies have begun to elucidate a role for E3 ubiquitin ligases as important mediators of the innate immune response. Our previous work defined a role for the ubiquitin ligase natural killer lytic-associated molecule (NKLAM/RNF19b) 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), a murine model of paramyxoviral pneumonia. NKLAM expression was significantly upregulated by SeV infection. SeV-infected mice that are deficient in NKLAM demonstrated significantly less weight loss than wild type mice. In vivo, Sendai virus replication was attenuated in NKLAM(-/-) mice. Autophagic flux and the expression of autophagy markers LC3 and p62/SQSTM1 were also less in NKLAM(-/-) mice. Using flow cytometry, we observed less neutrophils and macrophages in the lungs of NKLAM(-/-) mice during SeV infection. Additionally, phosphorylation of STAT1 and NFκB p65 was lower in NKLAM(-/-) than wild type mice. The dysregulated phosphorylation profile of STAT1 and NFκB in NKLAM(-/-) mice correlated with decreased expression of numerous proinflammatory cytokines that are regulated by STAT1 and/or NFκB. The lack of NKLAM and the resulting attenuated immune response is favorable to NKLAM(-/-) mice receiving a low dose of SeV; however, at a high dose of virus, NKLAM(-/-) mice succumbed to the infection faster than wild type mice. In conclusion, our novel results indicate that NKLAM plays a role in regulating the production of pro-inflammatory cytokines during viral infection.