Project description:Astrocyte activation is associated with progressive inflammatory demyelination in multiple sclerosis (MS). The molecular mechanisms underlying astrocyte activation remain incompletely understood. Recent studies have suggested that classical neurotransmitter receptors are implicated in the modulation of brain innate immunity. We investigated the role of dopamine signaling in the process of astrocyte activation. Here, we show the upregulation of dopamine D2 receptor (DRD2) in reactive astrocytes in MS brain and noncanonical role of astrocytic DRD2 in MS pathogenesis. Mice deficient in astrocytic Drd2 exhibit a remarkable suppression of reactive astrocytes and amelioration of experimental autoimmune encephalomyelitis (EAE). Mechanistically, DRD2 regulates the expression of 6-pyruvoyl-tetrahydropterin synthase, which modulates NF-κB activity through protein kinase C-δ. Pharmacological blockade of astrocytic DRD2 with a DRD2 antagonist dehydrocorybulbine remarkably inhibits the inflammatory response in mice lacking neuronal Drd2. Together, our findings reveal previously an uncharted role for DRD2 in astrocyte activation during EAE-associated CNS inflammation. Its therapeutic inhibition may provide a potent lever to alleviate autoimmune diseases.
Project description:Natalizumab, a recombinant humanized monoclonal antibody directed against the α4 subunit of the integrins α4ß1 and α4ß7, has been approved for the treatment of active relapsing-remitting MS. Although natalizumab is a highly beneficial drug that effectively reduces the risk of sustained disability progression and the rate of clinical relapses, some patients do not respond to it, and some are at higher risk of developing progressive multifocal leukoencephalopathy (PML). The histopathological effects after natalizumab therapy are still unknown. We, therefore, performed a detailed histological characterization of the CNS inflammatory cell infiltrate of 24 brain specimens from natalizumab treated patients, consisting of 20 biopsies and 4 autopsies and 21 MS controls. To complement the analysis, immune cells in blood and cerebrospinal fluid (CSF) of 30 natalizumab-treated patients and 42 MS controls were quantified by flow cytometry. Inflammatory infiltrates within lesions were mainly composed of T cells and macrophages, some B cells, plasma cells, and dendritic cells. There was no significant difference in the numbers of T cells or macrophages and microglial cells in lesions of natalizumab-treated patients as compared to controls. A shift towards cytotoxic T cells of a memory phenotype was observed in the CSF. Plasma cells were significantly increased in active demyelinating lesions of natalizumab-treated patients, but no correlation to clinical disability was observed. Dendritic cells within lesions were found to be reduced with longer ongoing therapy duration. Our findings suggest that natalizumab does not completely prevent immune cells from entering the CNS and is associated with an accumulation of plasma cells, the pathogenic and clinical significance of which is not known. As B cells are considered to serve as a reservoir of the JC virus, the observed plasma cell accumulation and reduction in dendritic cells in the CNS of natalizumab-treated patients may potentially play a role in PML development.
Project description:Multiple sclerosis (MS) is an autoimmune inflammatory disease of the CNS driven by the inflammatory activity of peripheral immune cells recruited to the CNS and by CNS-resident glial cells. MS pathogenesis has been linked to both genetic and environmental factors. In addition, the commensal flora have been shown to modulate immune processes relevant to MS pathogenesis. We discuss the effects of the gut microbiota on T cells and glial cells, and their relevance for the control of inflammation and neurodegeneration in MS. A better understanding of the gut-CNS axis will shed new light on the mechanisms of disease pathogenesis, and may help to guide the development of efficacious therapies for MS.
Project description:BackgroundThere are limited data to guide clinicians in differentiating tumefactive multiple sclerosis (TMS) from CNS neoplasms. Identifying distinguishing features will inform diagnosis and management and avoid unnecessary diagnostic biopsy. Our study aimed to determine the clinical and radiologic features that differentiate TMS from glioma and CNS lymphoma (CNSL) in patients who present with tumefactive lesions.MethodsWe retrospectively reviewed all patients with tumefactive lesions and histologically proven or clinically diagnosed TMS, glioma, or CNSL at our tertiary center from 1999 to 2012. Two independent blinded neuroradiologists rated MRI brain scans at presentation. We correlated patients' demographic, clinical, laboratory, and radiologic data to final diagnosis.ResultsA total of 133 patients (10 TMS, 85 glioma, 38 CNSL) were analyzed. Patients with TMS were younger and a greater proportion were women. Presenting symptoms did not distinguish between diagnoses. TMS lesions were smaller compared to glioma and CNSL, had no or mild mass effect, and were always associated with contrast enhancement. Radiologic features that were more frequent in TMS lesions were incomplete rim (open-ring) enhancement, incomplete peripheral diffusion restriction, and mixed T2 signal and CT hypoattenuation of MRI-enhancing components (all p < 0.05).ConclusionsRadiologic features but not presenting symptoms are useful in distinguishing TMS from CNS neoplasms.
Project description:Astrocyte activation is associated with progressive inflammatory demyelination in multiple sclerosis (MS). The molecular mechanisms underlying astrocyte activation remain incompletely understood. Recent studies have suggested that classical neurotransmitter receptors are implicated in the modulation of brain innate immunity. We investigated the role of dopamine signaling in the process of astrocyte activation. Here, we show the upregulation of dopamine D2 receptor (DRD2) in reactive astrocytes in MS brain and non-canonical role of astrocytic DRD2 in MS pathogenesis. Mice deficient in astrocytic Drd2 exhibit a remarkable suppression of reactive astrocytes and inflammation which are highly correlated with the amelioration of experimental autoimmune encephalomyelitis (EAE). Mechanistically, DRD2 regulates the expression of 6-pyruvoyl-tetrahydropterin synthase which modulates NF-κB activity through protein kinase C-δ. Pharmacological blockade of astrocytic DRD2 with a DRD2 antagonist dehydrocorybulbine remarkably inhibits the inflammatory response in mice lacking Drd2 in neurons. Together, our findings reveal previously uncharted roles for a DRD2 in astrocyte activation during EAE-associated CNS inflammation. Its therapeutic inhibition may provide a potent lever to alleviate autoimmune diseases.
Project description:Astrocyte activation is associated with progressive inflammatory demyelination in multiple sclerosis (MS). The molecular mechanisms underlying astrocyte activation remain incompletely understood. Recent studies have suggested that classical neurotransmitter receptors are implicated in the modulation of brain innate immunity. We investigated the role of dopamine signaling in the process of astrocyte activation. Here, we show the upregulation of dopamine D2 receptor (DRD2) in reactive astrocytes in MS brain and non-canonical role of astrocytic DRD2 in MS pathogenesis. Mice deficient in astrocytic Drd2 exhibit a remarkable suppression of reactive astrocytes and inflammation which are highly correlated with the amelioration of experimental autoimmune encephalomyelitis (EAE). Mechanistically, DRD2 regulates the expression of 6-pyruvoyl-tetrahydropterin synthase which modulates NF-κB activity through protein kinase C-δ. Pharmacological blockade of astrocytic DRD2 with a DRD2 antagonist dehydrocorybulbine remarkably inhibits the inflammatory response in mice lacking Drd2 in neurons. Together, our findings reveal previously uncharted roles for a DRD2 in astrocyte activation during EAE-associated CNS inflammation. Its therapeutic inhibition may provide a potent lever to alleviate autoimmune diseases.
Project description:The purpose of this study was to examine whether application of optical coherence tomography (OCT) measurements can provide a useful biomarker for distinguishing central nervous system (CNS) involvement in autoimmune connective tissue diseases (CTD) from multiple sclerosis (MS). An observational study included non-optic neuritis eyes of 121 individuals: 59 patients with MS, 30 patients with CNS involvement in CTD, and 32 healthy controls. OCT examination was performed in all subjects to measure retinal nerve fiber layer (RNFL) thickness, ganglion cell complex (GCC) thickness, ganglion cell layer-inner plexiform layer (GCIPL) thickness, and volume of the macula. There was a significant group effect with regard to superior optic disc RNFL, macular RNFL, GCC, and GCIPL thickness, and macular volume. Post-hoc analysis revealed that MS patients have significantly smaller macular volume and thinner superior optic disc RNFL, macular RNFL, GCC, and GCIPL compared to healthy controls. CTD patients have significantly smaller superior optic disc RNFL, GCIPL, and GCC thickness compared to healthy controls. However, no significant group differences were observed between the patient groups (MS vs. CTD) on any outcome. Although a prominent retinal thinning may be a useful biomarker in MS patients, in a general population of individuals with a confirmed CNS involvement the use of OCT is not specific enough to discriminate between MS and autoimmune CTD.
Project description:Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS) that results in significant neurodegeneration in the majority of those affected and is a common cause of chronic neurological disability in young adults1,2. Here, to provide insight into the potential mechanisms involved in progression, we conducted a genome-wide association study of the age-related MS severity score in 12,584 cases and replicated our findings in a further 9,805 cases. We identified a significant association with rs10191329 in the DYSF-ZNF638 locus, the risk allele of which is associated with a shortening in the median time to requiring a walking aid of a median of 3.7 years in homozygous carriers and with increased brainstem and cortical pathology in brain tissue. We also identified suggestive association with rs149097173 in the DNM3-PIGC locus and significant heritability enrichment in CNS tissues. Mendelian randomization analyses suggested a potential protective role for higher educational attainment. In contrast to immune-driven susceptibility3, these findings suggest a key role for CNS resilience and potentially neurocognitive reserve in determining outcome in MS.