Chloride channel-3 (ClC-3), a member of the ClC family of voltage-gated Cl channels, is involved in the resistance of tumor cells to chemotherapeutic drugs. Here, we report a new mechanism for ClC-3 in mediating multidrug resistance (MDR). ClC-3 was highly expressed in the P-glycoprotein (P-gp)-dependent human lung adenocarcinoma cell line (A549)/paclitaxel (PTX) and the human breast carcinoma cell line (MCF-7)/doxorubicin (DOX) resistant cells. Changes in the ClC-3 expression resulted in the development of drug resistance in formerly drug-sensitive A549 or MCF-7 cells, and drug sensitivity in formerly drug-resistant A549/Taxol and MCF-7/DOX cells. Double transgenic MMTV-PyMT/CLCN3 mice with spontaneous mammary cancer and ClC-3 overexpression demonstrated drug resistance to PTX and DOX. ClC-3 expression upregulated the expression of MDR1 messenger RNA and P-gp by activating the nuclear factor-κB (NF-κB)-signaling pathway. These data suggest that ClC-3 expression in cancer cells induces MDR by upregulating NF-κB-signaling-dependent P-gp expression involving another new mechanism for ClC-3 in the development of drug resistance of cancers.
Our objective was to examine the brain biopsies by histopathology and investigate the prognosis of patients with myelin oligodendrocyte glycoprotein antibody‐associated demyelinating pseudotumor. The clinical, MRI , and histological features of two patients with myelin oligodendrocyte glycoprotein antibody‐associated demyelinating pseudotumor were reviewed. Both patients were treated with steroid plus rituximab and followed up. The brain biopsies of both cases revealed T cells, macrophages, and complement‐mediated demyelination, which was in accord with multiple sclerosis‐like pathology. Moreover, both cases showed favorable response to steroid plus rituximab therapy. Our cases add a new variant to the myelin oligodendrocyte glycoprotein‐encephalomyelitis spectrum, which favorably responds to immunotherapy.
ObjectiveMyelin oligodendrocyte glycoprotein-associated disorders (MOGADs) are a rare new neurological autoimmune disease with unclear pathogenesis. Since a linkage of the disease to the human leucocyte antigen (HLA) has not been shown, we here investigated whether MOGAD is associated with the HLA locus.MethodsHLA genotypes of 95 patients with MOGADs, assessed between 2016 and 2018 from three academic centres, were compared with 481 healthy Chinese Han individuals. Patients with MOGADs included 51 paediatric-onset and 44 adult-onset cases. All patients were seropositive for IgG targeting the myelin oligodendrocyte glycoprotein (MOG).ResultsPaediatric-onset MOGAD was associated with the DQB1*05:02–DRB1*16:02 alleles (OR=2.43; OR=3.28) or haplotype (OR=2.84) of HLA class II genes. The prevalence of these genotypes in patients with paediatric-onset MOGAD was significantly higher than healthy controls (padj=0.0154; padj=0.0221; padj=0.0331). By contrast, adult-onset MOGAD was not associated with any HLA genotype. Clinically, patients with the DQB1*05:02–DRB1*16:02 haplotype exhibited significantly higher expanded disability status scale scores at onset (p=0.004) and were more likely to undergo a disease relapse (p=0.030). HLA–peptide binding prediction algorithms and computational docking analysis provided supporting evidence for the close relationship between the MOG peptide subunit and DQB1*05:02 allele. In vitro results indicated that site-specific mutations of the predicted target sequence reduced the antigen–antibody binding, especially in the paediatric-onset group with DQB1*05:02 allele.ConclusionsThis study demonstrates a possible association between specific HLA class II alleles and paediatric-onset MOGAD, providing evidence for the conjecture that different aetiology and pathogenesis likely underlie paediatric-onset and adult-onset cases of MOGAD.
Background A high-salt diet (HSD) is one of the major risk factors for acute ischemic stroke (AIS). As a potential mechanism, surplus salt intake primes macrophages towards a proinflammatory phenotype. In this study, whether HSD could blunt the efferocytic capability of macrophages after ischemic stroke, thus exacerbating post-stroke neural inflammation, was investigated. Methods Wild-type male C57BL/6 mice were fed with fodder containing 8% sodium chloride for 4 weeks and subjected to transient middle cerebral occlusion (tMCAO). Disease severity, macrophage polarization as well as efferocytic capability were evaluated. Bone marrow-derived macrophages were cultured in vitro, and the impact of high salinity on their efferocytic activity, as well as their expression of phagocytic molecules, were analyzed. The relationships among sodium concentration, macrophage phenotype, and disease severity in AIS patients were explored. Results HSD-fed mice displayed increased infarct volume and aggravated neurological deficiency. Mice fed with HSD suffered exacerbated neural inflammation as shown by higher inflammatory mediator expression and immune cell infiltration levels. Infiltrated macrophages within stroke lesions in HSD-fed mice exhibited a shift towards proinflammatory phenotype and impaired efferocytic capability. As assessed with a PCR array, the expression of triggering receptor expressed on myeloid cells 2 (TREM2), a receptor relevant to phagocytosis, was downregulated in high-salt-treated bone marrow-derived macrophages. Enhancement of TREM2 signaling restored the efferocytic capacity and cellular inflammation resolution of macrophages in a high salinity environment in vitro and in vivo. A high concentration of urine sodium in AIS patients was found to be correlated with lower TREM2 expression and detrimental stroke outcomes. Conclusions HSD inhibited the efferocytic capacity of macrophages by downregulating TREM2 expression, thus impeding inflammation resolution after ischemic stroke. Enhancing TREM2 signaling in monocytes/macrophages could be a promising therapeutic strategy to enhance efferocytosis and promote post-stroke inflammation resolution.
Immunoglobulin G against myelin oligodendrocyte glycoprotein (MOG-IgG) is detectable in neuromyelitis optica spectrum disorder (NMOSD) without aquaporin-4 IgG (AQP4-IgG), but its pathogenicity remains unclear. In this study, we explored the pathogenic mechanisms of MOG-IgG in vitro and in vivo and compared them with those of AQP4-IgG. MOG-IgG-positive serum induced complement activation and cell death in human embryonic kidney (HEK)-293T cells transfected with human MOG. In C57BL/6 mice and Sprague-Dawley rats, MOG-IgG only caused lesions in the presence of complement. Interestingly, AQP4-IgG induced astroglial damage, while MOG-IgG mainly caused myelin loss. MOG-IgG also induced astrocyte damage in mouse brains in the presence of complement. Importantly, we also observed ultrastructural changes induced by MOG-IgG and AQP4-IgG. These findings suggest that MOG-IgG directly mediates cell death by activating complement in vitro and producing NMOSDlike lesions in vivo. AQP4-IgG directly targets astrocytes, while MOG-IgG mainly damages oligodendrocytes.Keywords Neuromyelitis optica spectrum disorder Á Aquaporin-4 immunoglobulin G Á Myelin oligodendrocyte glycoprotein immunoglobulin G Á Complement-dependent cytotoxicity Á Transmission electron microscopy Ling Fang, Xinmei Kang, and Zhen Wang contributed equally to this work.
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