Interleukin 17 gene polymorphism is associated with anti-aquaporin 4 antibody-positive neuromyelitis optica in the Southern Han Chinese--a case control study

Neuromyelitis Optica Spectrum Disorders: Clinical Perspectives, Molecular Mechanisms, and Treatments

Neuromyelitis optica (NMO) is a rare autoimmune inflammatory disorder affecting the central nervous system (CNS), specifically the optic nerve and the spinal cord, with severe clinical manifestations, including optic neuritis (ON) and transverse myelitis. Initially, NMO was wrongly understood as a condition related to multiple sclerosis (MS), due to a few similar clinical and radiological features, until the discovery of the AQP4 antibody (NMO-IgG/AQP4-ab). Various etiological factors, such as genetic-environmental factors, medication, low levels of vitamins, and others, contribute to the initiation of NMO pathogenesis. The autoantibodies against AQP4 target the AQP4 channel at the blood–brain barrier (BBB) of the astrocyte end feet, which leads to high permeability or leakage of the BBB that causes more influx of AQP4-antibodies into the cerebrospinal fluid (CSF) of NMO patients. The binding of AQP4-IgG onto the AQP4 extracellular epitopes initiates astrocyte damage through complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC). Thus, a membrane attack complex is formed due to complement cascade activation; the membrane attack complex targets the AQP4 channels in the astrocytes, leading to astrocyte cell damage, demyelination of neurons and oligodendrocytes, and neuroinflammation. The treatment of NMOSD could improve relapse symptoms, restore neurological functions, and alleviate immunosuppression. Corticosteroids, apheresis therapies, immunosuppressive drugs, and B cell inactivating and complement cascade blocking agents have been used to treat NMOSD. This review intends to provide all possible recent studies related to molecular mechanisms, clinical perspectives, and treatment methodologies of the disease, particularly focusing on recent developments in clinical criteria and therapeutic formulations.

A Comprehensive Review on the Role of Genetic Factors in Neuromyelitis Optica Spectrum Disorder

Neuromyelitis optica spectrum disorders (NMOSD) comprise a variety of disorders being described by optic neuritis and myelitis. This disorder is mostly observed in sporadic form, yet 3% of cases are familial NMO. Different series of familial NMO cases have been reported up to now, with some of them being associated with certain HLA haplotypes. Assessment of HLA allele and haplotypes has also revealed association between some alleles within HLA-DRB1 or other loci and sporadic NMO. More recently, genome-wide SNP arrays have shown some susceptibility loci for NMO. In the current manuscript, we review available information about the role of genetic factors in NMO.

BLK polymorphisms and expression level in neuromyelitis optica spectrum disorder

Aim

This study aimed to determine the correlation between B‐lymphoid tyrosine kinase (BLK) polymorphism, mRNA gene expression of BLK, and NMOSD in a Chinese Han population.

Background

B‐lymphoid tyrosine kinase gene expressed mainly in B cells plays a key role in various autoimmune disorders. However, no studies have investigated the association of BLK polymorphisms with neuromyelitis optica spectrum disorder (NMOSD).

Methods

Han Chinese population of 310 subjects were recruited to analyze three single nucleotide polymorphisms (rs13277113, rs4840568, and rs2248932) under allele, genotype, and haplotype frequencies, followed by clinical characteristics stratified analysis. Real‐time PCR was used to analyze mRNA expression levels of BLK in the peripheral blood mononuclear cells of 64 subjects.

Results

Patients with NMOSD showed lower frequencies of the minor allele G of rs2248932 than healthy controls (odds ratio (OR) =0.57, 95% confidence intervals (CI) 0.39–0.83, p = 0.003). The association between minor allele G of rs2248932 and reduced NMOSD susceptibility was found by applying genetic models of inheritance (codominant, dominant, and recessive) and haplotypes analysis. Subsequently, by stratification analysis for AQP4‐positivity, the minor allele G frequencies of rs2248932 in AQP4‐positive subgroup were significantly lower than in the healthy controls (OR =0.46, 95% CI 0.30–0.72, p = 0.001). Notably, the genotype GG of rs2248932 was more frequent in AQP4‐negative subgroup (n = 14) than in AQP4‐positive subgroup (n = 93) (p = 0.003, OR =0.05, 95% CI =0.01–0.57). BLK mRNA expression levels in the NMOSD patients (n = 36) were lower than in healthy controls (n = 28) (p < 0.05). However, the acute non‐treatment (n = 7), who were untreated patients in the acute phase from the NMOSD group, showed BLK mRNA expression levels 1.8‐fold higher than healthy controls (n = 8) (p < 0.05).

Conclusion

This study evaluated that the minor allele G of rs2248932 in BLK is associated with reduced susceptibility to NMOSD and protected the risk of AQP4‐positive. BLK mRNA expression in NMOSD was lower as compared to healthy controls while significantly increased in acute‐untreated patients.

Interaction of HLA Class II rs9272219 and TMPO rs17028450 (Arg690Cys) Variants Affects Neuromyelitis Optica Spectrum Disorder Susceptibility in an Admixed Mexican Population

Neuromyelitis Optica Spectrum Disorder (NMOSD) is a demyelinating autoimmune disease of the central nervous system, more prevalent in individuals of non-European ancestry. Few studies have analyzed genetic risk factors in NMOSD, and HLA class II gene variation has been associated NMOSD risk in various populations including Mexicans. Thymopoietin (TMPO) has not been tested as a candidate gene for NMOSD or other autoimmune disease, however, experimental evidence suggests this gene may be involved in negative selection of autoreactive T cells and autoimmunity. We thus investigated whether the missense TMPO variant rs17028450 (Arg630Cys, frequent in Latin America) is associated with NMOSD, and whether this variant shows an interaction with HLA-class II rs9272219, previously associated with NMOSD risk. A total of 119 Mexican NMOSD patients, 1208 controls and 357 Native Mexican individuals were included. The HLA rs9272219 “T” risk allele frequency ranged from 21 to 68%, while the rs17028450 “T” minor allele frequency was as high as 18% in Native Mexican groups. Both rs9272219 and rs17028450 were significantly associated with NMOSD risk under additive models (OR = 2.48; p = 8 × 10^–10 and OR = 1.59; p = 0.0075, respectively), and a significant interaction between both variants was identified with logistic regression models (p = 0.048). Individuals bearing both risk alleles had an estimated 3.9-fold increased risk of NMOSD. To our knowledge, this is the first study reporting an association of TMPO gene variation with an autoimmune disorder and the interaction of specific susceptibility gene variants, that may contribute to the genetic architecture of NMOSD in admixed Latin American populations.

Neuromyelitis optica

Neuromyelitis optica (NMO; also known as Devic syndrome) is a clinical syndrome characterized by attacks of acute optic neuritis and transverse myelitis. In most patients, NMO is caused by pathogenetic serum IgG autoantibodies to aquaporin 4 (AQP4), the most abundant water-channel protein in the central nervous system. In a subset of patients negative for AQP4-IgG, pathogenetic serum IgG antibodies to myelin oligodendrocyte glycoprotein, an antigen in the outer myelin sheath of central nervous system neurons, are present. Other causes of NMO (such as paraneoplastic disorders and neurosarcoidosis) are rare. NMO was previously associated with a poor prognosis; however, treatment with steroids and plasma exchange for acute attacks and with immunosuppressants (in particular, B cell-depleting agents) for attack prevention has greatly improved the long-term outcomes. Recently, a number of randomized controlled trials have been completed and the first drugs, all therapeutic monoclonal antibodies, have been approved for the treatment of AQP4-IgG-positive NMO and its formes frustes.

Native American ancestry significantly contributes to neuromyelitis optica susceptibility in the admixed Mexican population

Neuromyelitis Optica (NMO) is an autoimmune disease with a higher prevalence in non-European populations. Because the Mexican population resulted from the admixture between mainly Native American and European populations, we used genome-wide microarray, HLA high-resolution typing and AQP4 gene sequencing data to analyze genetic ancestry and to seek genetic variants conferring NMO susceptibility in admixed Mexican patients. A total of 164 Mexican NMO patients and 1,208 controls were included. On average, NMO patients had a higher proportion of Native American ancestry than controls (68.1% vs 58.6%; p = 5 × 10^-6). GWAS identified a HLA region associated with NMO, led by rs9272219 (OR = 2.48, P = 8 × 10^-10). Class II HLA alleles HLA-DQB1*03:01, -DRB1*08:02, -DRB1*16:02, -DRB1*14:06 and -DQB1*04:02 showed the most significant associations with NMO risk. Local ancestry estimates suggest that all the NMO-associated alleles within the HLA region are of Native American origin. No novel or missense variants in the AQP4 gene were found in Mexican patients with NMO or multiple sclerosis. To our knowledge, this is the first study supporting the notion that Native American ancestry significantly contributes to NMO susceptibility in an admixed population, and is consistent with differences in NMO epidemiology in Mexico and Latin America.

The GTF2I rs117026326 polymorphism is associated with neuromyelitis optica spectrum disorder but not with multiple sclerosis in a Northern Han Chinese population

Multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) are common demyelinating disorders of the central nervous system. The etiology and pathogenesis of MS and NMOSD remain unclear. The pathogenesis of these two diseases involves a genetic predisposition as well as environmental factors. NMOSD sometimes co-exists with Sjögren's syndrome, systemic lupus erythematosus (SLE), and rheumatoid arthritis (RA), and these diseases are frequently associated with central nervous system disorder involvement, as manifest in MS- and NMOSD-like clinical features. Genetic variant rs117026326 upstream of the general transcription factor II-I (GTF2I) has been associated with primary Sjögren's syndrome, SLE and RA in East Asian populations. In this study, we genotyped single nucleotide rs117026326 polymorphisms of the GTF2I gene in 168 patients with MS, 144 patients with NMOSD, and 1403 healthy controls. We observed a significant genetic association between the variant rs117026326 and NMOSD (P = 1.09 × 10-11, OR = 2.535), however, the association with MS was not significant (P = .4289, OR = 1.129). Gene expression analyses showed that there was no significant association between the messenger RNA expression of GTF2I and genotypes at the variant. We conclude that the risk T allele of rs117026326 increases the risk of NMOSD, suggesting that NMOSD and MS may have different genetic risk factors.

Association Between BDNF Val66Met Polymorphism and Optic Neuritis Damage in Neuromyelitis Optica Spectrum Disorder

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune inflammatory disease of the central nervous system (CNS). The purpose of the study was to examine the association between the brain-derived neurotrophic factor (BDNF) Val66Met genotype and structural and functional optic nerve damage in the eyes of NMOSD patients. A total of 17 NMOSD subjects (34 eyes) were included in the study and were divided into subgroups based on optic neuritis (ON) history and BDNF Val66Met polymorphisms. The mean (range) age was 47.8 (23–78) years, and the mean (SD) disease duration was 7.4 (2–39) years. All participants had undergone optical coherence tomography (OCT) scans for global retinal nerve fiber layer (gRNFL) and ganglion cell-inner plexiform layer (GCIPL) thickness and multifocal visual evoked potential (mfVEP) test for amplitude and latency. BDNF Val66Met polymorphisms were genotyped in all participants. OCT and mfVEP changes were compared between two genotype groups (Met carriers vs. Val homozygotes) by using the generalised estimating equation (GEE) models. The BDNF Val66Met polymorphism was significantly associated with more severe nerve fiber layer damage and axonal loss in ON eyes of NMOSD subjects. Met carriers had more significantly reduced GCIPL (P = 0.002) and gRNFL (P < 0.001) thickness as well as more delayed mfVEP latency (P = 0.008) in ON eyes. No association was found between Val66Met variants and non-ON (NON)-eye of the participants. These findings suggest that the BDNF Val66Met polymorphism may be associated with optic nerve damage caused by acute ON attacks in NMOSD patients.

Identifying the culprits in neurological autoimmune diseases

The target organ of neurological autoimmune diseases (NADs) is the central or peripheral nervous system. Multiple sclerosis (MS) is the most common NAD, whereas Guillain-Barré syndrome (GBS), myasthenia gravis (MG), and neuromyelitis optica (NMO) are less common NADs, but the incidence of these diseases has increased exponentially in the last few years. The identification of a specific culprit in NADs is challenging since a myriad of triggering factors interplay with each other to cause an autoimmune response. Among the factors that have been associated with NADs are genetic susceptibility, epigenetic mechanisms, and environmental factors such as infection, microbiota, vitamins, etc. This review focuses on the most studied culprits as well as the mechanisms used by these to trigger NADs.

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Neurological autoimmune diseases are caused by a complex interaction between genes, environmental factors, and epigenetic deregulation.

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Infectious agents can cause an autoimmune reaction to myelin epitopes through molecular mimicry and/or bystander activation.

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Gut microbiota dysbiosis contributes to neurological autoimmune diseases.

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Smoking increases the risk of NADs through inflammatory signaling pathways, oxidative stress, and Th17 differentiation.

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Deficiency in vitamin D favors NAD development through direct damage to the central and peripheral nervous system.

Association of GTF2IRD1-GTF2I polymorphisms with neuromyelitis optica spectrum disorders in Han Chinese patients

Variants at the GTF2I repeat domain containing 1 (GTF2IRD1)–GTF2I locus are associated with primary Sjögren’s syndrome, systemic lupus erythematosus, and rheumatoid arthritis. Numerous studies have indicated that this susceptibility locus is shared by multiple autoimmune diseases. However, until now there were no studies of the correlation between GTF2IRD1–GTF2I polymorphisms and neuromyelitis optica spectrum disorders (NMOSD). This case control study assessed this association by recruiting 305 participants with neuromyelitis optica spectrum disorders and 487 healthy controls at the Department of Neurology, from September 2014 to April 2017. Peripheral blood was collected, DNA extracteds and the genetic association between GTF2IRD1–GTF2I polymorphisms and neuromyelitis optica spectrum disorders in the Chinese Han population was analyzed by genotyping. We found that the T allele of rs117026326 was associated with an increased risk of neuromyelitis optica spectrum disorders (odds ratio (OR) = 1.364, 95% confidence interval (CI) 1.019–1.828; P = 0.037). This association persisted after stratification analysis for aquaporin-4 immunoglobulin G antibodies (AQP4-IgG) positivity (OR = 1.397, 95% CI 1.021–1.912; P = 0.036) and stratification according to coexisting autoimmune diseases (OR = 1.446, 95% CI 1.072–1.952; P = 0.015). Furthermore, the CC genotype of rs73366469 was frequent in AQP4-IgG-seropositive patients (OR = 3.15, 95% CI 1.183–8.393, P = 0.022). In conclusion, the T allele of rs117026326 was associated with susceptibility to neuromyelitis optica spectrum disorders, and the CC genotype of rs73366469 conferred susceptibility to AQP4-IgG-seropositivity in Han Chinese patients. The protocol was approved by the Ethics Committee of West China Hospital of Sichuan University, China (approval number: 2016-31) on March 2, 2016.

Comprehensive review of neuromyelitis optica and clinical characteristics of neuromyelitis optica patients in Puerto Rico

Neuromyelitis optica (NMO) is an immune-mediated inflammatory disorder of the central nervous system. It is characterized by concurrent inflammation and demyelination of the optic nerve (optic neuritis [ON]) and the spinal cord (myelitis). Multiple studies show variations in prevalence, clinical, and demographic features of NMO among different populations. In addition, ethnicity and race are known as important factors on disease phenotype and clinical outcomes. There are little data on information about NMO patients in underserved groups, including Puerto Rico (PR). In this research, we will provide a comprehensive overview of all aspects of NMO, including epidemiology, environmental risk factors, genetic factors, molecular mechanism, symptoms, comorbidities and clinical differentiation, diagnosis, treatment, its management, and prognosis. We will also evaluate the demographic features and clinical phenotype of NMO patients in PR. This will provide a better understanding of NMO and establish a basis of knowledge that can be used to improve care. Furthermore, this type of population-based study can distinguish the clinical features variation among NMO patients and will provide insight into the potential mechanisms that cause these variations.

The combined effect of IL-17F and CCL20 gene polymorphism in susceptibility to multiple sclerosis in Egypt

BACKGROUND

Levels of CCL20 and its CCR6 receptor are elevated in many autoimmune diseases which help in the recruitment of T helper (Th17) cells to site of inflammation.

OBJECTIVES

Determine the value of single nucleotide polymorphism of CCL20 (rs6749704) and IL-17F (rs763780) genes and their concomitant effect on the serum CCL20 level and susceptibility to MS in Egyptian patients.

SUBJECTS AND METHODS

Blood samples were collected from 83 patients and 95 healthy subjects. Serum levels of CCL20 were measured by ELISA. The DNA was analyzed for rs6749704 and rs763780 using Genotyping Taqman assay.

RESULTS

The mean serum levels of CCL20 in the MS group were significantly higher than healthy group (P < 0.001). Frequencies of CT genotype of rs6749704 in CCL20 gene and C allele in MS patients were significantly higher compared to controls. Also significant increase of rs763780 in IL-17F gene was detected in MS patients. Concomitant polymorphism in both genes in MS patients showed an increase risk to MS rather than individual locus.

CONCLUSION

CCL20 may play an important role in the pathogenesis of MS. Both allelic variation of (rs6749704) within CCL20 gene and (rs763780) within IL-17F gene can be considered risk factor for development of MS in Egyptian patients.

Immunopathogenesis in Myasthenia Gravis and Neuromyelitis Optica

Myasthenia gravis (MG) and neuromyelitis optica (NMO) are autoimmune channelopathies of the peripheral neuromuscular junction (NMJ) and central nervous system (CNS) that are mainly mediated by humoral immunity against the acetylcholine receptor (AChR) and aquaporin-4 (AQP4), respectively. The diseases share some common features, including genetic predispositions, environmental factors, the breakdown of tolerance, the collaboration of T cells and B cells, imbalances in T helper 1 (Th1)/Th2/Th17/regulatory T cells, aberrant cytokine and antibody secretion, and complement system activation. However, some aspects of the immune mechanisms are unique. Both targets (AChR and AQP4) are expressed in the periphery and CNS, but MG mainly affects the NMJ in the periphery outside of CNS, whereas NMO preferentially involves the CNS. Inflammatory cells, including B cells and macrophages, often infiltrate the thymus but not the target—muscle in MG, whereas the infiltration of inflammatory cells, mainly polymorphonuclear leukocytes and macrophages, in NMO, is always observed in the target organ—the spinal cord. A review of the common and discrepant characteristics of these two autoimmune channelopathies may expand our understanding of the pathogenic mechanism of both disorders and assist in the development of proper treatments in the future.

Infections in neuromyelitis optica spectrum disorder

Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory astrocytopathy that has both genetic and environmental causes. A growing body of evidence suggests that the presence of several infectious agents correlates with the development of NMOSD. In this review, we summarize studies that either support or present evidence against the hypothesized association between infection and NMOSD. We will also present an overview of potential mechanisms underlying the pathogenesis of NMOSD. Finally, we provide some beneficial properties that infectious elements may have based on "hygiene hypothesis". It is of great clinical significance to further investigate the complex mechanisms by which infections may affect autoimmune diseases to develop better strategies to prevent and treat them, although so far no causal link between infectious agents and NMOSD has been established.

Mutation of the cellular adhesion molecule NECL2 is associated with neuromyelitis optica spectrum disorder

AIMS

To investigate the association of the Nectin/Necl family genes with the risk of developing NMOSD.

METHODS

Whole-exome sequencing was performed on two familial NMOSD cases and two unaffected family members. Additionally, 106 patients with sporadic NMOSD and 212 healthy controls (HCs) underwent screening for mutant Necl2. Finally, the molecular weight and cellular localization of mutant NECL2 was examined in transfected HeLa cells.

RESULTS

We identified a novel deletion mutation in Necl2 (c.1052_1060delCCACCACCA; p. Thr351_Thr353del), which was associated with disease manifestation in the NMOSD familial cases. The frequency at which the mutation occurred in patients with sporadic NMOSD was significantly higher than for HCs (5.7% and 0, respectively; p<0.01). The mutation was located in the extracellular domain close to the transmembrane region, at a point in the protein sequence characterized by threonine enrichment. The mutant NECL2 had a lower molecular weight and exhibited defective trafficking to the cell surface.

CONCLUSIONS

Our results suggest that the Necl2 mutation identified herein may be associated with the risk of developing NMOSD. Furthermore, mutated NECL2 may play a role in the pathogenesis of the disease, potentially through its roles in axonal regeneration and/or via neuron-glia interactions that are relevant to myelination.

Association of TNFSF4 Polymorphisms with Neuromyelitis Optica Spectrum Disorders in a Chinese Population

The tumor necrosis factor ligand superfamily member 4 (TNFSF4) gene encodes a vital co-stimulatory molecule of the immune system and has been identified as a susceptibility locus for systemic lupus erythematosus, systemic sclerosis, and primary Sjögren's syndrome. However, the association of TNFSF4 polymorphisms with neuromyelitis optica spectrum disorders (NMOSD), an inflammatory, demyelinating autoimmune disease of the central nervous system, has not yet been investigated. To evaluate whether TNFSF4 polymorphisms contribute to risk of NMOSD, four single-nucleotide polymorphisms (SNPs) (rs1234315, rs2205960, rs704840, and rs844648) were selected and genotyped in a cohort of 312 patients with NMOSD and 487 healthy controls. Our study showed that rs844648 was associated with an increased risk of NMOSD, according to the allelic model (OR = 1.30, 95% CI 1.06-1.59, P = 0.011, Pcorr = 0.044). Significant associations of rs844648 (OR = 1.67, 95% CI 1.17-2.38, P = 0.005, Pcorr = 0.02) and rs704840 (OR = 1.75, 95% CI 1.17-2.63, P = 0.007, Pcorr = 0.027) with NMOSD occurrence were also observed under the recessive model. Moreover, linkage disequilibrium analysis revealed two blocks within TNFSF4; in one block, the haplotype A_rs844648G_rs704840 significantly increased the risk of NMOSD, whereas G_rs844648T_rs704840 reduced the risk. This study demonstrates an association between TNFSF4 polymorphisms and susceptibility for the development of NMOSD in the Chinese population.

Th17 cells in neuromyelitis optica spectrum disorder: a review

Neuromyelitis optica spectrum disorder (NMOSD) has been identified as a central nervous system (CNS) autoimmune inflammatory disorder, which has been recognized as a B cell-mediated humoral immune disease. However, cases have been reported indicating that some of the neuromyelitis optica (NMO) patients have been resistant to B cell-related treatments. Recently, more and more evidence has shown that T cell-mediated immunity may take part in the pathogenesis of NMOSD, especially in the Th17 phenotype. In our PUBMED search, we used the following keywords: Th17 cell, Th17 cell-related cytokines, T cells, B cells, B cell-related productions, NMO, NMOSD, recurrent/bilateral optic neuritis, recurrent transverse myelitis and longitudinally extensive transverse myelitis. We systemically reviewed the role of Th17 cells and Th17 cell-related cytokines in NMOSD. We found that Th17 cells and Th17-related cytokines, such as IL-6, IL-1β, IL-17, IL-21, IL-22, IL-23 and TGF-β, are not only directly involved in the pathogenesis but also collaborated with B cells and B cell-related antibody production to induce CNS lesions. Th17 cell-related therapy has also been reviewed in this article, and the data suggested that Th17 may be a new therapeutic target of NMOSD.

Association study between IL-17A and IL-17F gene polymorphism and myasthenia gravis in Chinese patients

Alleles of IL-17A and IL-17F genes were reported to be associated with many inflammatory and autoimmune disorders in Asian patients. Serum level and mRNA of IL-17A in peripheral blood mononuclear cells were reported to be significantly higher in MG patients than in healthy controls. In experimental autoimmune myasthenia gravis (EAMG) animals, IL-17 may have effects on the severity of MG. This study investigated the association between four SNPs of IL-17A and IL-17F gene (rs8193036, rs2275913 and rs3748067 in IL-17A; rs763780 in IL-17F) and MG in Chinese patients. The allele frequencies were compared between 480 MG patients and 487 healthy controls, between each MG subgroup and the control group, and between each pairs of MG subgroups. Subgroups were specified by clinical features (onset age, gender, thymoma, AChRAb and muscle involvement at onset) and maximal severity during the follow-up. No associations were found between the four SNPs of IL-17A and IL-17F gene and MG in Chinese patients.

Epidemiological, clinical, and immunological characteristics of neuromyelitis optica: A review

The aim of this study was to review the epidemiological and clinical characteristics of neuromyelitis optica (NMO) and the immunopathological mechanisms involved in the neuronal damage. NMO is an inflammatory demyelinating autoimmune disease of the central nervous system that most commonly affects the optic nerves and spinal cord. NMO is thought to be more prevalent among non-Caucasians and where multiple sclerosis (MS) prevalence is low. NMO follows a relapsing course in more than 80-90% of cases, which is more commonly in women. It is a complex disease with an interaction between host genetic and environmental factors and the main immunological feature is the presence of anti-aquaporin 4 (AQP4) antibodies in a subset of patients. NMO is frequently associated with multiple other autoantibodies and there is a strong association between NMO with other systemic autoimmune diseases. AQP4-IgG can cause antibody-dependent cellular cytotoxicity (ADCC) when effector cells are present and complement-dependent cytotoxicity (CDC) when complement is present. Acute therapies, including corticosteroids and plasma exchange, are designed to minimize injury and accelerate recovery. Several aspects of NMO pathogenesis remain unclear. More advances in the understanding of NMO disease mechanisms are needed in order to identify more specific biomarkers to NMO diagnosis.

IL2RA Allele Increases Risk of Neuromyelitis Optica in Southern Han Chinese

Background:

Neuromyelitis optica (NMO) and multiple sclerosis (MS) are chronic neuro-inflammatory diseases believed to arise from complex interactions between environmental and genetic factors. Recently, single nucleotide polymorphisms (SNPs) in interleukin (IL)-2 and -7 receptor alpha genes have been identified as novel susceptibility alleles for MS in genome-wide association studies. However, similar research on NMO is limited. We aimed to investigate the association of IL2RA SNPs rs2104286 and rs12722489 and IL7RA SNP rs6897932 with Southern Han Chinese NMO and MS patients.

Methods:

Frequencies of the three SNPs were examined in Southern Han Chinese mS cases (n=78), NMS cases (n=67) and controls (n=133) using sequencing-based typing.

Results:

The rs2104286G frequency in the IL2RA gene was significantly higher in NMO patients than in controls (puncorr=0.013, pcorr=0.026, OR:1.942, 95%CI:1.146-3.291).

Conclusion:

The rs2104286 G allele in IL2RA is present at higher frequencies in NMO patients than in healthy controls within a Southern Han Chinese population.

Association of IL-17 gene polymorphisms and serum level with graft versus host disease after allogeneic hematopoietic stem cell transplantation

BACKGROUND

Cytokines are important factors determining the outcome of transplantation. Host ability in cytokine production may be affected by cytokine genes polymorphisms. The aim of the present study was to investigate the effect of IL-17 gene polymorphisms on outcome of Hematopoietic stem cell transplantation.

MATERIALS AND METHODS

A total of 60 bone marrow recipients were included in this study. Twenty-five recipients (41.66%) underwent a GVHD. IL-17 gene polymorphisms were evaluated by PCR-RFLP method and the serum levels were also checked by ELISA.

RESULTS

No significant differences in distribution of the IL-17(A/G) (rs3819025) genotypes and alleles were observed between two groups. But, IL-17 (A/G, -197) GG genotype was found to be significantly higher in GVHD group compared to those of non-GVHD group (P = 0.04). Interestingly, after stratification of patients according severity of GVHD, IL-17 (rs3819025) G allele was remained significantly higher in GVHD grade (0-I) group compared to those of grade (II-IV) group (P = 0.05). In addition, after categorization of patients according to their sex, IL-17-197 GG genotype showed a significant association with non-GVHD in male patients (P = 0.05). IL-17 serum levels did not show any significant difference between GVHD and non GVHD groups.

CONCLUSION

Results indicated that IL-17197 GG genotype, G allele of (rs3819025) and its serum level have predictive values for severity of GVHD. Also, IL-17-197 GG genotype is a sex dependent genetic risk factor for development of GVHD, but this subject need to be studied in different population.

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

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.

Neuromyelitis optica: clinical features, immunopathogenesis and treatment

The term 'neuromyelitis optica' ('Devic's syndrome', NMO) refers to a syndrome characterized by optic neuritis and myelitis. In recent years, the condition has raised enormous interest among scientists and clinical neurologists, fuelled by the detection of a specific serum immunoglobulin (Ig)G reactivity (NMO-IgG) in up to 80% of patients with NMO. These autoantibodies were later shown to target aquaporin-4 (AQP4), the most abundant water channel in the central nervous system (CNS). Here we give an up-to-date overview of the clinical and paraclinical features, immunopathogenesis and treatment of NMO. We discuss the widening clinical spectrum of AQP4-related autoimmunity, the role of magnetic resonance imaging (MRI) and new diagnostic means such as optical coherence tomography in the diagnosis of NMO, the role of NMO-IgG, T cells and granulocytes in the pathophysiology of NMO, and outline prospects for new and emerging therapies for this rare, but often devastating condition.

IL-17F but not IL-17A gene polymorphism confers risk to multiple sclerosis in a Chinese Han population

Interleukin-17 has been shown to be associated with autoimmune disease. The aim of the current study is to investigate the potential association of IL-17 polymorphisms with multiple sclerosis (MS) in Chinese Han patients. Two SNPs, rs763780 of IL-17F gene and rs2275913 of IL-17A gene were genotyped in 622 MS patients and 743 healthy controls by using a polymerase chain reaction-restriction fragment length polymorphism method (PCR-RFLP). Allele and genotype frequencies distribution of the two SNPs were examined between patients and controls using the Chi-Square test. All genotypic and allelic frequencies of the tested IL-17 polymorphisms in control cohort were in Hardy-Weinberg equilibrium. A significantly increased frequency of rs763780 TT genotype (corrected p value (Pc)=0.024, odds ratio=1.472, 95% CI=1.133-1.913) and T allele (corrected P (Pc)=0.018, odds ratio=1.446, 95% CI=1.134-1.844) was detected in MS patients compared with controls. The genotypic and allelic frequencies of rs2275913 in IL-17A gene were not different between patients with MS and controls. These results suggest that rs763780 is associated with multiple sclerosis in a Chinese Han population.

Immunopathogenesis of neuromyelitis optica

Neuromyelitis optica (NMO, Devic's syndrome) is a clinical syndrome characterized by optic neuritis and (mostly longitudinally extensive) myelitis. If untreated, NMO usually takes a relapsing course and often results in blindness and tetra- or paraparesis. The discovery of autoantibodies to aquaporin-4, the most abundant water channel in the CNS, in 70-80% of patients with NMO (termed NMO-IgG or AQP4-Ab) and subsequent investigations into the pathogenic impact of this new reactivity have led to the recognition of NMO as an autoimmune condition and as a disease entity in its own right, distinct from classic multiple sclerosis. Here, we comprehensively review the current knowledge on the role of NMO-IgG/AQP4-Ab, B cells, T cells, and the innate immune system in the pathogenesis of NMO.

Associations of CD6, TNFRSF1A and IRF8 polymorphisms with risk of inflammatory demyelinating diseases

AIMS

Multiple sclerosis (MS) and neuromyelitis optica (NMO) are inflammatory autoimmune diseases that affect the central nervous system. Several genome-wide and candidate gene studies have identified genetic polymorphisms associated with the risk of MS or NMO. In particular, two recently published studies of meta-analysis in European-origin populations have suggested associations of single-nucleotide polymorphisms (SNPs) in CD6, TNFRSF1A and IRF8 with MS. The aim of our study was to assess the associations between SNPs in these three genes and the risk of inflammatory demyelinating disease (IDD) including MS and NMO. To the best of our knowledge, this is the first time such a study has been performed in an Asian population.

METHODS

A total of 21 SNPs of CD6, TNFRSF1A and IRF8 were genotyped in 178 IDD cases (79 MS and 99 NMO patients) and 237 normal controls in a Korean population.

RESULTS

Logistic analyses revealed that one SNP in CD6 (rs12288280, P = 0.04) and three SNPs in TNFRSF1A (rs767455, rs4149577 and rs1800693, P = 0.01-0.03) were associated with NMO. However, there was no association of IRF8 polymorphisms with IDD, including MS and NMO. Using further information from the SNP Function Prediction website, two exonic splicing enhancers (ESEs), including the polymorphic site of rs767455, were predicted to be binding sites for splicing factors (SRp55, SF2/ASF2 and SF2/ASF1).

CONCLUSION

Although additional studies are needed, our findings could provide information regarding the genetic aetiology of IDD in the Korean population.

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.

Cerebrospinal fluid high-mobility group box protein 1 in neuromyelitis optica and multiple sclerosis

BACKGROUND

Neuromyelitis optica (NMO) and multiple sclerosis (MS) are two autoimmune inflammatory demyelinating diseases in the central nervous system. Interleukin (IL)-6 and IL-17 may play important roles in the pathogenesis of these diseases. High-mobility group box protein 1 (HMGB1) can activate the nuclear factor light chain enhancer of activated B cells and release cytokines such as IL-6 and IL-17. However, whether cerebrospinal fluid (CSF) HMGB1 levels were altered in NMO and MS patients is still unclear.

OBJECTIVES

It was our aim to measure the CSF HMGB1 concentration in NMO patients and explore their relationship with IL-6, IL-17 and disease activity.

METHODS

CSF HMGB1 was measured by enzyme-linked immunosorbent assay in NMO (n = 22) and MS (n = 18) patients as well as in controls (n = 14).

RESULTS

CSF HMGB1 was notably higher in the NMO group compared with controls (p = 0.007). CSF HMGB1 positively correlated with IL-6 and IL-17 in NMO patients (IL-6, p = 0.034; IL-17, p < 0.001).

CONCLUSIONS

In conclusion, our study suggests that CSF levels of HMGB1 are increased in patients with NMO and reflect the neuroinflammatory process.

Human aquaporin 4281-300 is the immunodominant linear determinant in the context of HLA-DRB1*03:01: relevance for diagnosing and monitoring patients with neuromyelitis optica

OBJECTIVE To identify linear determinants of human aquaporin 4 (hAQP4) in the context of HLA-DRB1*03:01. DESIGN In this controlled study with humanized experimental animals, HLA-DRB1*03:01 transgenic mice were immunized with whole-protein hAQP4 emulsified in complete Freund adjuvant. To test T-cell responses, lymph node cells and splenocytes were cultured in vitro with synthetic peptides 20 amino acids long that overlap by 10 amino acids across the entirety of hAQP4. The frequency of interferon γ, interleukin (IL) 17, granulocyte-macrophage colony-stimulating factor, and IL-5-secreting CD4+ T cells was determined by the enzyme-linked immunosorbent sport assay. Quantitative immunofluorescence microscopy was performed to determine whether hAQP4281-300 inhibits the binding of anti-hAQP4 recombinant antibody to surface full-length hAQP4. SETTING Academic neuroimmunology laboratories. SUBJECTS Humanized HLA-DRB1*03:01+/+ H-2b-/- transgenic mice on a B10 background. RESULTS Peptide hAQP4281-300 generated a significantly (P &lt;.01) greater TH1 and TH17 immune response than any of the other linear peptides screened. This 20mer peptide contains 2 dominant immunogenic 15mer peptides. hAQP4284-298 induced predominantly an IL-17 and granulocyte-macrophage colony-stimulating factor TH cell phenotype, whereas hAQP4285-299 resulted in a higher frequency of TH1 cells. hAQP4281-300 did not interfere with recombinant AQP4 autoantibody binding. CONCLUSIONS hAQP4281-330 is the dominant linear immunogenic determinant of hAQP4 in the context of HLA-DRB1*03:01. Within hAQP4281-330 are 2 dominant immunogenic determinants that induce differential TH phenotypes. hAQP4 determinants identified in this study can serve as diagnostic biomarkers in patients with neuromyelitis optica and may facilitate the monitoring of treatment responses to pharmacotherapies.