Probes for INS

Severe influenza is often associated with disease manifestations outside the respiratory tract. Whilst pro-inflammatory cytokines can be detected in the lungs and blood of infected patients, the role of extra-respiratory organs in the production of pro-inflammatory cytokines is unknown. Here, we show that both pandemic H1N1 and highly pathogenic H5N1 virus induce expression of TNFα, IL-6 and IL-8 in the respiratory tract and central nervous system. In addition, H5N1 virus induced cytokines in the heart, pancreas, spleen, liver and jejunum. Together, these data suggest that extra-respiratory tissues contribute to systemic cytokine responses which may increase the severity of influenza.

The present study demonstrates HIV-1 Tat-mediated epigenetic downregulation of microglial miR-124 and its association with microglial activation. Exposure of mouse primary microglia isolated from newborn pups of either sex to HIV-1 Tat resulted in decreased expression of primary miR-124-1, primary miR-124-2 as well as the mature miR-124. In parallel, HIV-1 Tat exposure to mouse primary microglial cellsresulted in increased expression of DNA methylation enzymes, such as DNMT1, DNMT3A, and DNMT3B that were also accompanied by increased global DNA methylation. Bisulfite-converted genomic DNA sequencing in the HIV-1 Tat exposed mouse primary microglial cellsfurther confirmed increased DNA methylation of the primary miR-124-1 and primary miR-124-2 promoters. Bioinformatic analyses identified MECP2 as a novel 3'-UTR target of miR-124. This was further validated in mouse primary microglial cells wherein HIV-1 Tat-mediated downregulation of miR-124 resulted in increased expression of MECP2, leading in turn to further repression of miR-124 via the feedback loop. In addition to MECP2, miR-124 also modulated the levels of STAT3 through its binding to the 3'-UTR, leading to microglial activation. Luciferase assays and Ago2 immunoprecipitation determined the direct binding between miR-124 and 3'-UTR of both MECP2 and STAT3. Gene silencing of MECP2 and DNMT1 and overexpression of miR-124 blocked HIV-1 Tat-mediated downregulation of miR-124 and microglial activation. In vitro findings were also confirmed in the basal ganglia of SIV-infected rhesus macaques (both sexes). In summary, our findings demonstrate a novel mechanism of HIV-1 Tat-mediated activation of microglia via downregulation of miR-124, leading ultimately to increased MECP2 and STAT3 signaling.
SIGNIFICANCE STATEMENT
Despite the effectiveness of combination antiretroviral therapy in controlling viremia, the CNS continues to harbor viral reservoirs. The persistence of low-level virus replication leads to the accumulation of early viral proteins including HIV-1 Tat protein. Understanding the epigenetic/molecular mechanism(s) by which viral proteins such as HIV-1 Tat can activate microglia is thus of paramount importance. This study demonstrated HIV-1 Tat-mediated DNA methylation of the miR-124 promoter leads to its downregulation with a concomitant upregulation of the MECP2-STAT3-IL6 resulting in microglial activation. These findings reveal an unexplored epigenetic/molecular mechanism(s) underlying HIV-1 Tat-mediated microglial activation, thereby providing a potential target for the development of therapeutics aimed at ameliorating microglial activation and neuroinflammation in the context of HIV-1 infection.

Pericytes are mural cells of blood microvessels which play a crucial role at the neurovascular interface of the central nervous system. They are involved in the regulation of blood-brain barrier integrity, angiogenesis, clearance of toxic metabolites, capillary hemodynamic responses, and neuroinflammation, and they demonstrate stem cell activity. Morphological and molecular studies to characterize brain pericytes recently pointed out some heterogeneity in pericyte population. Nevertheless, a clear definition of pericyte subtypes is still lacking. Here, we demonstrate that a fraction of brain pericytes express Connexin 30 (Cx30), a gap junction protein, which, in the brain parenchyma, was thought to be exclusively found in astrocytes. Cx30 could thus be a candidate protein in the composition of the gap junction channels already described between endothelial cells and pericytes. It could also form hemichannels or acts in a channel-independent manner to regulate pericyte morphology, as already observed in astrocytes. Altogether, our results suggest that Cx30 defines a novel brain pericyte subtype.

Coxsackieviruses of group B (CVB) are well-known causes of acute and chronic myocarditis. Chronic myocarditis can evolve into dilated cardiomyopathy (DCM) characterized by fibrosis and cardiac remodeling. Interleukin-1β (IL-1β) plays a decisive role in the induction of the inflammatory response as a consequence of viral replication. In this study, we analyzed the effects of IL-1β neutralization on the transition of acute to chronic myocarditis in a mouse model of CVB3 myocarditis. Mice were treated with an anti-murine IL-1β antibody as a surrogate for Canakinumab at different time points post CVB3 infection. Treatment was performed in the early phase (day 1-14 pi, day 3-14 pi) or at a later stage of myocarditis (day 14-28 pi). Subsequently, the hearts were examined histologically, immunohistochemically and by molecular biology. A significant reduction of viral replication, cardiac damage and inflammation was found after administration of the antibody in the early phase and in the later phase of infection. Furthermore, less collagen I deposition and a considerable reduction of fibrosis were found in antibody-treated mice. Using microarray analysis, a significant upregulation of various extracellular matrix and fibrosis-associated molecules was found in CVB3-infected mice, including TGF-β, TIMP-1 and MMP12, as well as diverse matricellular proteins, whereas, these molecules were significantly downregulated in all IL-1β antibody-treated infected mice. Neutralization of IL-1β at different stages of enteroviral infection prevents the development of chronic viral myocarditis by reducing inflammation, interstitial fibrosis and adverse cardiac remodeling. These findings are relevant for the treatment of patients with acute and chronic myocarditis.

The cytokine interleukin-1β (IL-1β) is known to stimulate proinflammatory immune responses and impair β-cell function and viability, all critical events in the pathogenesis of type 1 diabetes (T1D). Here we evaluate the effect of SER140, a small peptide IL-1β receptor antagonist, on diabetes progression and cellular pancreatic changes in female nonobese diabetic (NOD) mice. Eight weeks of treatment with SER140 reduced the incidence of diabetes by more than 50% compared with vehicle, decreased blood glucose, and increased plasma insulin. Additionally, SER140 changed the endocrine and immune cells dynamics in the NOD mouse pancreas. Together, the data suggest that SER140 treatment postpones the onset of diabetes in female NOD mice by interfering with IL-1β activated pathways.