Mice with Different Susceptibility to Japanese Encephalitis Virus Infection Show Selective Neutralizing Antibody Response and Myeloid Cell Infectivity

Japanese encephalitis virus (JEV) is a mosquito-borne flavivirus that causes public health problems in Asian countries. Only a limited number of JEV-infected individuals show symptoms and develop severe encephalitis, indicating host-dependent susceptibilities.C3H/HeN and DBA/2 mice, which exhibit different mortalities when infected by intraperitoneal inoculation with JEV, were used as experimental models to compare viral pathogenesis and host responses. One hundred infectious virus particles killed 95% of C3H/HeN mice whereas only 40% of DBA/2 mice died. JEV RNA was detected with similar low levels in peripheral lymphoid organs and in the sera of both mouse strains. High levels of viral and cytokine RNA were observed simultaneously in the brains of C3H/HeN and DBA/2 mice starting on days 6 and 9 post-infection, respectively. The kinetics of the cytokines in sera correlated with the viral replication in the brain. Significantly earlier and higher titers of neutralizing antibodies were detected in the DBA/2 strain. Primary embryonic fibroblasts, bone marrow-derived dendritic cells and macrophages from the two mouse strains were cultured. Fibroblasts displayed similar JEV replication abilities, whereas DBA/2-derived myeloid antigen-presenting cells had lower viral infectivity and production compared to the C3H/HeN–derived cells. may be elements associated with late and decreased mouse neuroinvasion

CD148 Deficiency in Fibroblasts Promotes the Development of Pulmonary Fibrosis.

RATIONALE: The receptor-like protein tyrosine phosphatase eta (CD148/PTPRJ) exerts anti-fibrotic effects in experimental pulmonary fibrosis via interactions with its ligand syndecan-2; however, the role of CD148 in human pulmonary fibrosis remains incompletely characterized. OBJECTIVES: We investigated the role of CD148 in the profibrotic phenotype of fibroblasts in idiopathic pulmonary fibrosis (IPF). METHODS: Conditional CD148 fibroblast-specific knockout mice were generated and exposed to bleomycin, and then assessed for pulmonary fibrosis. Lung fibroblasts (mouse lung, and human IPF lung), and precision cut lung slices (PCLS) from human IPF patients were isolated and subjected to experimental treatments. A CD148-activating 18-aa mimetic peptide (SDC2-pep) derived from syndecan-2 was evaluated for its therapeutic potential. MEASUREMENTS AND MAIN RESULTS: CD148 expression was downregulated in IPF lungs and fibroblasts. In human IPF lung fibroblasts, silencing of CD148 increased extracellular matrix production and resistance to apoptosis, whereas overexpression of CD148 reversed the profibrotic phenotype. CD148 fibroblast-specific knockout mice displayed increased pulmonary fibrosis after bleomycin challenge compared to control mice. CD148-deficient fibroblasts exhibited hyperactivated PI3K/Akt/mTOR signaling, reduced autophagy and increased p62 accumulation, which induced NF-kB activation and profibrotic gene expression. SDC2-pep reduced pulmonary fibrosis in vivo, and inhibited IPF-derived fibroblast activation. In PCLS from IPF and control patients, SDC2-pep attenuated profibrotic gene expression in IPF and normal lungs stimulated with pro-fibrotic stimuli. CONCLUSIONS: Lung fibroblast CD148 activation reduces p62 accumulation, which exerts anti-fibrotic effects by inhibiting NF-kB mediated profibrotic gene expression. Targeting the CD148 phosphatase with activating ligands such as SDC2-pep may represent a potential therapeutic strategy in IPF

PD-1 up-regulation on CD4+ T cells promotes pulmonary fibrosis through STAT3-mediated IL-17A and TGF-β1 production

Pulmonary fibrosis is a progressive inflammatory disease with high mortality and limited therapeutic options. Previous genetic and immunologic investigations suggest common intersections between idiopathic pulmonary fibrosis (IPF), sarcoidosis, and murine models of pulmonary fibrosis. To identify immune responses that precede collagen deposition, we conducted molecular, immunohistochemical, and flow cytometric analysis of human and murine specimens. Immunohistochemistry revealed programmed cell death-1 (PD-1) up-regulation on IPF lymphocytes. PD-1+CD4+ T cells with reduced proliferative capacity and increased transforming growth factor-β (TGF-β)/interleukin-17A (IL-17A) expression were detected in IPF, sarcoidosis, and bleomycin CD4+ T cells. PD-1+ T helper 17 cells are the predominant CD4+ T cell subset expressing TGF-β. Coculture of PD-1+CD4+ T cells with human lung fibroblasts induced collagen-1 production. Strikingly, ex vivo PD-1 pathway blockade resulted in reductions in TGF-β and IL-17A expression from CD4+ T cells, with concomitant declines in collagen-1 production from fibroblasts. Molecular analysis demonstrated PD-1 regulation of the transcription factor STAT3 (signal transducer and activator of transcription 3). Chemical blockade of STAT3, using the inhibitor STATTIC, inhibited collagen-1 production. Both bleomycin administration to PD-1 null mice or use of antibody against programmed cell death ligand 1 (PD-L1) demonstrated significantly reduced fibrosis compared to controls. This work identifies a critical, previously unrecognized role for PD-1+CD4+ T cells in pulmonary fibrosis, supporting the use of readily available therapeutics that directly address interstitial lung disease pathophysiology