Adaway, Michele

Abstract Severe influenza A virus infection typically triggers excessive and detrimental lung inflammation with massive cell infiltration and hyper-production of cytokines and chemokines. Defining research models to alleviate lung damage without compromising viral control is critical. We identified a novel function for nuclear matrix protein 4 (NMP4), a zinc-finger-containing transcription factor in regulating lung inflammation and antiviral innate immune responses. Nmp4-deficient mice are protected from H1N1 influenza infection, losing less body weight compared to the wild-type mice. Nmp4-deficiency does not affect viral clearance or adaptive immune responses, but significantly reduces the accumulation of neutrophils and monocytes in the lungs and the early inflammation. Consistent with fewer innate cells in the airways, infected Nmp4-deficient mice show decreased expression of chemokine genes Ccl2 and Cxcl1 as well as pro-inflammatory cytokine genes Il1b and Il6. We further reveal that NMP4 binds to the promoters and/or conserved non-coding sequences (CNS) of Ccl2 and Cxcl1 in mouse lung epithelial cells. Besides, the knockdown of NMP4 by CRISPR/Cas9 or siRNA significantly lessens the luciferase activities of Ccl2 and Cxcl1 promoters and/or CNS. Taken together, our data suggest that NMP4 regulates monocyte- and neutrophil-attracting chemokine expression in airway epithelial cells upon influenza infection, resulting in exaggerated innate inflammation and lung tissue damage.

Abstract Mesenchymal stem/progenitor cells (MSPCs) have immunomodulatory activity. We previously observed that osteoprogenitors and CD8+T cells are increased in the bone marrow (BM) of mice lacking the transcription factor Nmp4. Transcriptome analysis of MSPCs from Nmp4−/− and wild type (WT) mice revealed significant changes in genes related to innate immune responses, including reduced expression of Tlr3 and Mda5 in the null MSPCs. Loss of Nmp4 increased mRNA translation, ribosomal biogenesis, and Gadd34 expression in MSPCs; collectively, these processes likely promote the unfolded protein response (UPR), expanding the processing capacity of the endoplasmic reticulum. Therefore, we hypothesized that disabling Nmp4 would improve innate immune cell function. To test this, Nmp4−/− mice (C57BL6) were infected intranasally with influenza A/PR8 (H1N1; 150pfu). Despite having similar virus load in the lung, H1N1-infected Nmp4−/− mice lost less body weight than WT mice post infection and had improved survival. Infected Nmp4−/− mice had fewer infiltrating neutrophils (PMNs; CD11b+/Ly6G+) and monocytes (CD11b+/SiglecFNeg/Ly6GNeg/Ly6C+) in bronchoalveolar lavage (BAL) but more BAL macrophages (CD11c+/SiglecF+); CD4+ and CD8+ T cells were not different between genotypes. Ex vivo, Nmp4-deficiency did not alter the differentiation of BM marrow-derived macrophages; however, Chil3/Ym1 and Alox15 mRNA expression was reduced in Nmp4−/− macrophages polarized with IL-4/IL-13, suggesting cell-autonomous regulation of M2 macrophage activation by Nmp4. Our data point to Nmp4 as a novel regulator of innate immunity and influenza response in mice.