High salt diet (HSD) is one of the most important risk factors that contribute to many vascular diseases including ischemic stroke. One proposed mechanism underlying the disruption of blood-brain barrier (BBB) mediated by HSD is indirectly through enhancing blood pressure. The direct role of HSD on BBB integrity is unclear. Our purpose is to determine whether and how HSD might be involved in BBB breakdown during ischemia. To test that, we induced model of cerebral ischemia by permanent middle cerebral artery ligation (pMCAL) in either normal diet or HSD fed mice. We observed that HSD significantly enhanced ischemic brain damage which was associated with enhanced BBB disruption, increased leukocytes infiltration and loss of tight junction (TJ) proteins expression without apparently altering blood pressure. Our in vitro experiment also revealed that sodium chloride (NaCl) treatment down-regulated TJ protein expression by endothelial cells and substantially increased BBB permeability during starvation. Inhibition of p38/MAPK/SGK1 pathway eliminated the effect of NaCl on BBB permeability in vitro. In addition, we noticed a positive correlation between urinary sodium levels and ischemic lesion size in stroke patients. Together, our study demonstrates a hypertension-independent role of HSD during ischemia and provides rationale for post cerebral ischemic attack management.

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MicroRNA 182 is important for the clonal expansion of CD4 + T cells (Th) following IL-2 stimulation and is a potential therapeutic target for autoimmune diseases. In the present study, we investigated the role of microRNA 182 in the differentiation of pro-inflammatory CD4 + T helper cell by overexpressing or silencing microRNA 182 expression both in in vivo and in vitro settings. We report that in the studied Chinese cohort, microRNA 182 is upregulated in patients with relapse and remitting multiple sclerosis (RRMS) and this upregulation is associated with increased IFN-γ producing CD4 + Th1 cells in the circulation. In the murine experimental autoimmune encephalomyelitis (EAE) model, global microRNA 182 overexpression exacerbates clinical symptoms and results in augmented CD4 + IFN-γ + Th1 and CD4 + IL-17 + Th17 differentiation in vivo. Addition of microRNA 182 mimics in vitro represses both the protein expression and transcriptional activity of hypoxia induced factor 1α (HIF-1α) but increases the level of IFN-γ transcripts in sorted murine CD4 + T cells. Together, our results provide evidence that microRNA 182 may be one of the transitional hubs contribution to regulate Th cells expansion in response to self-antigens and differentiation of antigen specific Th cells during the progression of autoimmune inflammations.Keywords: autoimmunity r EAE/MS r HIF-1α r microRNA 182 r Th1 cells Additional supporting information may be found online in the Supporting Information section at the end of the article.

The classically activated (M1) macrophage has been shown to play an indispensable role in experimental autoimmune encephalomyelitis (EAE), the animal model of multiple sclerosis (MS). However, most studies focus on the effect of macrophage on CNS demyelination of EAE; whether the M1 macrophage participates in early EAE and the molecular mechanism underlying remains unclear. Here, we showed that the immunity-related GTPase family member 1 (Irgm1), also known as LRG-47, was expressed in M1 macrophages of draining lymph nodes (dLNs) from C57BL/6 mice with early EAE, and the IRGM1 heterozygote substantially reduced M1 macrophage accumulation in dLNs and spleen of the primary EAE stage. In vitro silence of IRGM1 in M1 macrophages impaired NOS2 expression and inflammatory cytokine release. We also found that IRGM1 knockout (Irgm1) in M1 macrophages increased Akt activation but attenuated NF-κB p65 activation, which may reveal Irgm1-mediated mechanisms of action. Interestingly, macrophage depletion in vivo inhibited Th1/Th17 differentiation in the spleen and promoted regulatory T cell (T) polarization in dLNs at 7 d postimmunization (dpi). Moreover, we observed that M1 macrophages in vitro promoted Th1/Th17 differentiation, which was reversed by treatment with IRGM1 small interfering RNA (siRNA), anti-TNF-α, or anti-IL-1β mAb. These results suggest that the M1 macrophage may promote Th1/Th17 cell differentiation during the early EAE, and the proinflammatory function of M1 cells requires Irgm1.