Guixian Zhao

MicroRNA miR-326 regulates T H -17 differentiation and is associated with the pathogenesis of multiple sclerosis

Interleukin 17 (IL-17)-producing T helper cells (TH-17 cells) are increasingly recognized as key participants in various autoimmune diseases, including multiple sclerosis. Although sets of transcription factors and cytokines are known to regulate TH-17 differentiation, the role of noncoding RNA is poorly understood. Here we identify a TH-17 cell–associated microRNA, miR-326, whose expression was highly correlated with disease severity in patients with multiple sclerosis and mice with experimental autoimmune encephalomyelitis (EAE). In vivo silencing of miR-326 resulted in fewer TH-17 cells and mild EAE, and its overexpression led to more TH-17 cells and severe EAE. We also found that miR-326 promoted TH-17 differentiation by targeting Ets-1, a negative regulator of TH-17 differentiation. Our data show a critical role for microRNA in TH-17 differentiation and the pathogenesis of multiple sclerosis.

Blocking A2B Adenosine Receptor Alleviates Pathogenesis of Experimental Autoimmune Encephalomyelitis via Inhibition of IL-6 Production and Th17 Differentiation

Adenosine is a key endogenous signaling molecule that regulates immune responses. A2B adenosine receptor (AR) is a relatively low-affinity receptor for adenosine, and the activation of A2BAR is believed to require pathological level of adenosine that is associated with ischemia, inflammation, trauma, or other types of stress. The role of A2BAR in the pathogenesis of multiple sclerosis (MS) is still unclear. In this study, we discovered that A2BAR was upregulated both in the peripheral blood leukocytes of MS patients and the peripheral lymphoid tissues of experimental autoimmune encephalomyelitis (EAE) mice. A2BAR-specific antagonists, CVT-6883 and MRS-1754, alleviated the clinical symptoms of EAE and protected the CNS from immune damage. A2BAR-knockout mice also developed less severe EAE. Further study indicated that blocking or deleting A2BAR inhibited Th17 cell differentiation by blocking IL-6 production from APCs such as dendritic cells. In dendritic cells, A2BAR was also upregulated during the development of EAE. CVT-6883 and genetic deletion of A2BAR significantly reduced adenosine-mediated IL-6 production. The phospholipase Cβ–protein kinase C and p38 MAPK pathways were found to be involved in the A2BAR-mediated IL-6 production. Our findings not only revealed the pathological role of A2BAR in EAE, but also suggested that this receptor might be a new therapeutic target for the development of anti-MS drugs.

Impaired regulatory function and enhanced intrathecal activation of B cells in neuromyelitis optica: distinct from multiple sclerosis

Background: The effective treatment of neuromyelitis optica (NMO) with rituximab has suggested an important role for B cells in NMO pathogenesis. Objective: To explore the antibody-independent function of B cells in NMO and relapsing–remitting multiple sclerosis (RRMS). Methods: Fifty-one NMO patients and 42 RRMS patients in an acute relapse phase and 37 healthy controls (HC) were enrolled in the study. The B cell expression of B cell activating factor receptor (BAFF-R), CXCR5 and very late antigen-4 (VLA-4), the B cell production of interleukin (IL)-10 and interferon (IFN)-γ and the proportion of circulating memory and CD19+CD24highCD38high regulatory B cells were evaluated by flow cytometry. The cerebrospinal fluid (CSF) levels of BAFF and CXCL13 were determined by enzyme-linked immunosorbent assay (ELISA). Results: The CD19+CD24highCD38high regulatory B cell levels and the B cell expression of IL-10 were significantly lower in NMO patients than in RRMS patients and the HC. In aquaporin-4 antibody (AQP4-ab)-positive NMO patients, the B cell IL-10 production and CD19+CD24highCD38high regulatory B cell levels were even lower than in AQP4-ab-negative NMO patients. The CSF BAFF and CXCL13 levels were significantly higher in NMO patients than in patients with RRMS and other non-inflammatory neurologic diseases (ONDs). Conclusions: The immuno-regulatory properties of B cells are significantly impaired in NMO patients and particularly in AQP4-ab-positive NMO patients. The elevated CSF levels of BAFF and CXCL13 in NMO suggest an enhanced intrathecal B cell recruitment and activation. Our results further define the distinct immunological nature of NMO and RRMS from the B cell perspective.

The antiepileptic drug valproic acid restores T cell homeostasis and ameliorates pathogenesis of experimental autoimmune encephalomyelitis

Background: Dysregulation of T cell survival and apoptosis is the common cause of autoimmune diseases including multiple sclerosis (MS). Results: Valproic acid (VPA) treatment restores the dysregulated apoptosis of T cells and reduces the symptoms of EAE. Conclusion: In addition to the antiepileptic activity, VPA also regulates T cell homeostasis. Significance: As an orally available drug, VPA might be used to treat autoimmune diseases, such as MS. Maintaining a constant number and ratio of immune cells is one critical aspect of the tight regulation of immune homeostasis. Breakdown of this balance will lead to autoimmune diseases such as multiple sclerosis (MS). The antiepileptic drug valproic acid (VPA) was reported to regulate the growth, survival, and differentiation of many cells. However, its function in T cell homeostasis and MS treatment remains unknown. In this study, VPA was found to reduce spinal cord inflammation, demyelination, and disease scores in experimental autoimmune encephalomyelitis, a mouse model of MS. Further study indicated that VPA induces apoptosis in activated T cells and maintains the immune homeostasis. This effect was found to be mainly mediated by the caspase-8/caspase-3 pathway. Interestingly, this phenomenon was also confirmed in T cells from normal human subjects and MS patients. Considering the long history of clinical use and our new findings, we believe VPA might be a safe and effective therapy for autoimmune diseases, such as multiple sclerosis.

Variants in the promoter region of CYP7A1 are associated with neuromyelitis optica but not with multiple sclerosis in the Han Chinese population

Multiple sclerosis (MS) and neuromyelitis optica (NMO) are common autoimmune demyelinating disorders of the central nervous system. The exact etiology of each remains unclear. CYP7A1 was reported to be associated with NMO in Korean patients, but this is yet to be confirmed in other populations. In this study, we used Sanger sequencing to detect SNPs in the promoter region of CYP7A1 in a population consisting of unrelated patients and controls from the Han Chinese population (129 MS; 89 NMO; 325 controls). Two known SNPs, −204A>C (rs3808607) and −469T>C (rs3824260), and a novel SNP (−208G>C) were identified in the 5′-UTR of CYP7A1. The −204A>C was in complete linkage with −469T>C and both were associated with NMO but not with MS. Results suggest that the CYP7A1 allele was associated with NMO. NMO and MS have different genetic risk factors. This further supports the emerging evidence that MS and NMO are distinct disorders.

Variants of CYP27B1 are associated with both multiple sclerosis and neuromyelitis optica patients in Han Chinese population.

Multiple sclerosis (MS) and neuromyelitis optica (NMO) are chronic demyelinating diseases of the central nervous system (CNS). Recently, variants of vitamin D metabolizing genes, including rs12368653, rs10876994, rs118204009 and rs703842 in CYP27B1, and rs2248359 in CYP24A1 have been identified to be associated with the pathogenicity of MS in Caucasian populations. However, these results have not been replicated in Han Chinese population. Here we investigated the association of these variants with MS and NMO susceptibility in 149 MS patients, 110 NMO patients and 294 healthy controls using MassARRAY system and Sanger sequencing. We found that the frequencies of the A allele of rs703842 were higher in MS patients than controls (p=0.032), and statistical differences were observed in the genotypes of both rs703842 (p=0.013) and rs10876994 (p=0.001) between NMO patients and controls. In addition, we found difference in the genotype of rs12368653 between MS patients and controls (p=0.008). However, no difference was found in rs2248359 among these three groups. The reported rare mutation p.R389H (rs118204009) was not found in our study. In conclusion, our study suggested that variants of CYP27B1 were associated with both MS and NMO patients in Han Chinese population.

Variants of autophagy-related gene 5 are associated with neuromyelitis optica in the Southern Han Chinese population.

Abstract Neuromyelitis optica (NMO) and multiple sclerosis (MS) are autoimmune demyelinating diseases of the central nervous system. The discovery of NMO immunoglobulin G (NMO-IgG) antibody has improved the clinical definition of NMO. Recently, the autophagy-related genes (ATGs) have been proved to be associated with several autoimmune and inflammation diseases. Increased T cell expression of ATG5 may be correlated with the pathogenesis of inflammatory demyelination in MS. However, the association of ATG5 variants with MS and NMO patients has not been well studied. In this study, five ATG5 variants were genotyped in 144 MS patients, 109 NMO patients and 288 controls in the Han Chinese population. In the cohort of NMO patients, we observed that the CC genotype of rs548234 increased susceptibility to NMO (p = 0.016), while the allele T of rs548234 (p = 0.003) and the allele A of rs6937876 (p = 0.009) acted as protective factors for NMO-IgG positive NMO patients. However, no association was found between ATG5 variants and MS patients. These results indicated that ATG5 variants are associated with NMO but not MS patients, which may provide a clue for further clarifying the autoimmune mechanisms of autophagy-related pathogenesis in NMO.

Novel Function of Extracellular Matrix Protein 1 in Suppressing Th17 Cell Development in Experimental Autoimmune Encephalomyelitis

Multiple sclerosis (MS) is a chronic inflammatory disease of the CNS characterized by demyelination and axonal damage. Experimental autoimmune encephalomyelitis (EAE) is a well-established animal model for human MS. Although Th17 cells are important for disease induction, Th2 cells are inhibitory in this process. In this article, we report the effect of a Th2 cell product, extracellular matrix protein 1 (ECM1), on the differentiation of Th17 cells and the development of EAE. Our results demonstrated that ECM1 administration from day 1 to day 7 following the EAE induction could ameliorate the Th17 cell responses and EAE development in vivo. Further study of the mechanism revealed that ECM1 could interact with αv integrin on dendritic cells and block the αv integrin–mediated activation of latent TGF-β, resulting in an inhibition of Th17 cell differentiation at an early stage of EAE induction. Furthermore, overexpression of ECM1 in vivo significantly inhibited the Th17 cell response and EAE induction in ECM1 transgenic mice. Overall, our work has identified a novel function of ECM1 in inhibiting Th17 cell differentiation in the EAE model, suggesting that ECM1 may have the potential to be used in clinical applications for understanding the pathogenesis of MS and its diagnosis.

No association between identified multiple sclerosis non-MHC risk loci and neuromyelitis optica

Neuromyelitis optica (NMO) and multiple sclerosis (MS) are both autoimmune inflammatory and demyelinating disorders of the central nervous system. Recently, more than 50 MS-susceptibility single-nucleotide polymorphisms (SNPs) have been detected outside the major histocompatibility complex (MHC) region. In this study, we aimed to evaluate the association of these identified non-MHC MS risk loci with Chinese patients with NMO. Thirty-five non-MHC SNPs were selected and genotyped by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) in 110 NMO patients and 332 controls from southeastern China. Among the 35 SNPs, only one, rs1800693 in the TNFRSF1A locus, was nominally associated with NMO (P = 0.045, OR = 1.550, 95% CI = 1.007–2.384). However, none of the 35 SNPs was associated with NMO after Bonferroni correction. Our results showed no association between these identified non-MHC MS risk loci and NMO, suggesting there are genetic differences in the etiology of NMO and MS.

Clinical features and mutation spectrum in Chinese patients with CADASIL: A multicenter retrospective study

To characterize clinical features and mutation spectrum in Chinese patients with CADASIL.