Gene Polymorphisms for Both Auto-antigen and Immune-Modulating Proteins Are Associated with the Susceptibility of Autoimmune Myasthenia Gravis

Association between Cytotoxic T-Lymphocyte-Associated Antigen 4 (CTLA-4) Locus and Early-Onset Anti-acetylcholine Receptor-Positive Myasthenia Gravis in Serbian Patients

Genome-wide association studies (GWAS) have provided strong evidence that early- and late-onset MG have different genetic backgrounds. Recent in silico analysis based on GWAS results revealed rs231735 and rs231770 variants within CTLA-4 locus as possible MG causative genetic factors. We aimed to explore the association of rs231735 and rs231770 with MG in a representative cohort of Serbian patients. We conducted an age-, sex-, and ethnicity-matched case-control study. Using TaqMan allele discrimination assays, the frequency of rs231735 and rs231770 genetic variants was examined in 447 AChR-MG patients and 447 matched controls. There was no significant association of rs231735 and rs231770 with the entire MG cohort (P > 0.05). Nevertheless, when stratifying patients into early-onset (n = 183) and late-onset MG (n = 264), we found early-onset patients had a significantly lower frequency of the rs231735 allele T compared to controls (OR = 0.734, 95% CI = 0.575-0.938, p10e6 permutation < 0.05), and rs231735 genotype TT and rs231770 genotype TT had a protective effect on early-onset MG (OR = 0.548, 95% CI = 0.339-0.888, and OR = 0.563, 95% CI = 0.314-1.011, p10e6 permutation < 0.05). Consequently, we found that individuals with the rs231735-rs231770 haplotype GC had a higher risk for developing early-onset MG (OR = 1.360, P = 0.027, p10e6 permutation < 0.05). Our results suggest that CTLA-4 rs231735 and rs231770 may be risk factors only for patients with early-onset MG in Serbian population.

Cytokines Single Nucleotide Polymorphisms (SNPs) Association With Myasthenia Gravis (MG) In Algerian Patients: A Case-Control Study On A Small Group

ABSTRACT

Myasthenia gravis (MG) is an autoimmune disease of multifactorial etiology in which genetic factors and cytokines seem to play an important role. The aim of this study was to investigate potential associations of cytokines single nucleotide polymorphisms (SNPs) and MG in Algerian patients. We performed a case-control study that included 27 patients and 74 healthy subjects. Cytokines SNPs genotyping was performed by the polymerase chain reaction sequence-specific primers (PCR-SSP) method. Our results showed that the TNF-α -308G/A (P < 0.005) and TGF-β1 +869T/T (P < 0.05) genotypes were more frequent among patients with MG compared with healthy individuals, whereas TNF-α -308G/G (P < 0.0001), TGF-β1 +869T/C (P < 0.05), and IFN-γ +874A/A (P < 0.05) were less frequent. Our results also showed that IL-10 and IL-6 SNPs did not show any significant difference in distribution between MG patients and healthy individuals. Our observations support the hypothesis that implicates genetic variants of certain cytokines in MG. However, ours results should be replicated with a larger sample size. In addition, the precise underlying processes remain to be clarified.

HIGHLIGHTS

TNF-α -308G/A and TGF-β1 +869T/C genotypes predispose to MG.IFN-γ +874A/A genotype protects against MG.IL-6 -174C/G SNP is not associated with MG.

Epigenome-wide DNA methylation analysis of myasthenia gravis

Myasthenia gravis (MG) is a common neuromuscular junction disorder and autoimmune disease mediated by several antibodies. Several studies have shown that genetic factors play an important role in MG pathogenesis. To gain insight into the epigenetic factors affecting MG, we report here genome-scale DNA methylation profiles of MG. DNA was extracted from eight MG patients and four healthy controls for genome-wide DNA methylation analysis using the Illumina HumanMethylation 850K BeadChip. Verification of pyrosequencing was conducted based on differential methylation positions. Subsequently, C2C12 and HT22 cell lines (derived from mouse) were treated with demethylation drugs. Transcribed mRNA of the screened differential genes was detected using quantitative real-time PCR. The control and MG group were compared, and two key probe positions were selected. The corresponding genes were CAMK1D and CREB5 (P < 0.05). Similarly, the myasthenic crisis (MC) and non-MC group were compared and four key probe positions were selected. The corresponding genes were SAV1, STK3, YAP1, and WWTR1 (P < 0.05). Subsequently, pyrosequencing was performed for verification, revealing that hypomethylation of CAMK1D was significantly different between the MG and control group (P < 0.001). Moreover, transcription of CREB5, PKD, YAP1, and STK3 genes in the C2C12 cells was downregulated (P < 0.05) after drug treatment, but only YAP1 mRNA was downregulated in HT22 cells (P < 0.05). This is the first study to investigate genome-scale DNA methylation profiles of MG using 850 K BeadChip. The identified molecular markers of methylation may aid in the prevention, diagnosis, treatment, and prognosis of MG.

Insights Into the Host Contribution of Endocrine Associated Immune-Related Adverse Events to Immune Checkpoint Inhibition Therapy

Blockade of immune checkpoints transformed the paradigm of systemic cancer therapy, enabling substitution of a cytotoxic chemotherapy backbone to one of immunostimulation in many settings. Invigorating host immune cells against tumor neo-antigens, however, can induce severe autoimmune toxicity which in many cases requires ongoing management. Many immune-related adverse events (irAEs) are clinically and pathologically indistinguishable from inborn errors of immunity arising from genetic polymorphisms of immune checkpoint genes, suggesting a possible shared driver for both conditions. Many endocrine irAEs, for example, have analogous primary genetic conditions with varied penetrance and severity despite consistent genetic change. This is akin to onset of irAEs in response to immune checkpoint inhibitors (ICIs), which vary in timing, severity and nature despite a consistent drug target. Host contribution to ICI response and irAEs, particularly those of endocrine origin, such as thyroiditis, hypophysitis, adrenalitis and diabetes mellitus, remains poorly defined. Improved understanding of host factors contributing to ICI outcomes is essential for tailoring care to an individual’s unique genetic predisposition to response and toxicity, and are discussed in detail in this review.

CHRNA1 promotes the pathogenesis of primary focal hyperhidrosis

The aim of the study was to elucidate the involvement of cholinergic receptor nicotinic alpha 1 subunit (CHRNA1) in the pathogenesis of primary focal hyperhidrosis (PFH). The hyperhidrosis mouse model was constructed using pilocarpine injection. The expression levels of CHRNA1 in sweat gland tissues of PFH patients and hyperhidrosis mice were compared using Western blots and quantitative real-time PCR (qRT-PCR) analyses. Sweat secretion in hyperhidrosis mice treated with small-interfering RNA (siRNA) targeting CHRNA1 (si-CHRNA1) or non-specific siRNA were compared. Sweat secretory granules in the sweat gland cells of hyperhidrosis mice were examined using transmission electron microscopy. The serum level of acetylcholine was measured using enzyme-linked immunosorbent assay, while markers associated with PFH, including Aquaporin 5 (AQP5) and Calcium Voltage-Gated Channel Subunit Alpha1 C (CACNA1C), were assessed using immunohistochemical assay and Western blots. Brain-derived neurotrophic factor (BDNF) and Neuregulin 1 (NRG-1) in sympathetic ganglia axons of hyperhidrosis mice were quantified using Western blots. CHRNA1 up-regulation is a characteristic of the sweat glands of PFH patients and Hyperhidrosis mice. Silencing CHRNA1 decreased sweat secretion and the number of sweat secretory granules of hyperhidrosis mice. Serum acetylcholine, as well as AQP5 and CACNA1C expression in the sweat glands, was reduced by siCHRNA1. BDNF1 and NRG-1 levels in the sympathetic ganglia axons were also attenuated by siCHRNA1 treatment. CHRNA1 up-regulation is a potential biomarker of PFH and downregulating CHRNA1 could alleviate the symptoms of PFH through inactivating the sympathetic system.

CTLA-4 Expression Plays a Role in PSC and PBC Progression

BACKGROUND & AIMS

The pathogenesis of primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) remains unclear. The aim of this study was to reveal certain single nucleotide polymorphisms (SNP) in genes for regulatory proteins in the immunologic pathway possibly going along with susceptibility of attaining PBC or PSC.

METHODS

126 patients with either PBC or PSC with clinical and laboratory data were enrolled in the study. SNPs in three genes (CTLA-4, ICOS, and FOX-P3) which are suspected to play a key role in the autoimmune pathway were analyzed to determine allele variants. Gene expression was measured by RealTime PCR using mRNA.

RESULTS

Patients with cirrhosis had a lower number of CTLA-4 copies than patients without cirrhosis (p = 0.04). Accordingly, patients with lower CTLA-4 copies had a poorer recovery of gamma-glutamyltransferase (GGT) in course of their disease (-69.8 U/l vs. -176.1 U/l p = 0.04). Two SNP allele variants (CTLA4 rs733618 and FOXP3 rs2280883) associated with low CTLA-4 expression could be determined. Patients having both variants showed worsening of GGT (-61.7 U/l vs. -132.6 U/l, p = 0.04) and a trend towards a more progressive disease in terms of cirrhosis. (24% vs. 13% p = ns).

CONCLUSIONS

Low expression of CTLA-4 is associated with a more advanced disease in patients with PBC and PSC. Furthermore, we identified two SNP allele variants (CTLA4-SNP rs733618 and FOXP3-SNP rs2280883) associated with a lower CTLA-4 expression and possibly a more severe course of the diseases. Taken together, these results provide further evidence for the involvement of the immune system in the pathogenesis of these two cholestatic liver diseases. Lay summary: Primary biliary cholangitis and primary sclerosing cholangitis are chronic diseases of the bile ducts. Their cause remains widely unclear, but evidence suggests the immune system plays a central role. This study shows that gene alterations connected to the immune system might play a role in the course of the disease.

Investigation of the Correlation between Graves' Ophthalmopathy and CTLA4 Gene Polymorphism

Graves’ disease (GD) is an autoimmune inflammatory disease, and Graves’ ophthalmopathy (GO) occurs in 25–50% of patients with GD. Several susceptible genes were identified to be associated with GO in some genetic analysis studies, including the immune regulatory gene CTLA4. We aimed to find out the correlation of CTLA4 gene polymorphism and GO. A total of 42 participants were enrolled in this study, consisting of 22 patients with GO and 20 healthy controls. Chi-square or Fisher’s exact test were used to appraise the association between Graves’ ophthalmopathy and CTLA4 single nucleotide polymorphisms (SNPs). All regions of CTLA4 including promoter, exon and 3’UTR were investigated. There was no nucleotide substitution in exon 2 and exon 3 of CTLA4 region, and the allele frequencies of CTLA4 polymorphisms had no significant difference between patients with GO and controls. However, the genotype frequency of “TT” genotype in rs733618 significantly differed between patients with GO and healthy controls (OR = 0.421, 95%CI: 0.290–0.611, p = 0.043), and the “CC” and “CT” genotype in rs16840252 were nearly significantly differed in genotype frequency (p = 0.052). Haplotype analysis showed that CTLA4 Crs733618Crs16840252 might increase the risk of GO (OR = 2.375, 95%CI: 1.636–3.448, p = 0.043). In conclusion, CTLA4 Crs733618Crs16840252 was found to be a potential marker for GO, and these haplotypes would be ethnicity-specific. Clinical application of CTLA4 Crs733618Crs16840252 in predicting GO in GD patients may be beneficial.

Association between CTLA-4 gene polymorphism and myasthenia gravis in a Chinese cohort

Abnormal CTLA-4 expression is involved in the development of myasthenia gravis (MG), and serum CTLA-4 levels are positively correlated with serum anti-AChR antibody concentration, which might be related with the severity of MG. Polymorphism in CTLA-4 gene is associated with various autoimmune disorders. We investigated the association of polymorphism in CTLA-4 gene with the clinical variables and severity of MG. The frequencies of alleles and genotypes were compared between 480 MG patients and 487 healthy controls, as well as among subgroups of MG patients. The frequency of rs733618*C allele is significantly higher in MG group and several subgroups than in control group. Genotype is not found as independent factor for essential clinical variables of MG. The frequency of rs231775*A allele is significantly lower in ocular onset subgroup than in control group, and the frequencies of rs231775*A allele and rs3087243*A allele are significantly lower in ocular onset subgroup than in generalized onset subgroup. Genotypes of the two SNPs are found as independent factors for ocular onset. The frequency of rs231775*A allele is significantly lower in mild subgroup than that in control group. Genotype is not found as independent factor for mild severity. A haplotype containing rs733618*C, rs231775*G and rs3087243*G is identified to increase the general risk of MG by 1.278-fold and ocular onset MG subgroup by 1.362-fold. There is association of rs733618 with the general susceptibility of MG, and association of rs231775 and rs3087243 with the susceptibility of ocular onset MG, but no association with the severity of MG.

Susceptible loci associated with autoimmune disease as potential biomarkers for checkpoint inhibitor-induced immune-related adverse events

Unprecedented successes regarding cancer immunotherapy have been achieved, in which therapeutic agents are used to target immune cells rather than cancer cells. The most effective immunotherapy to date is the group of immune checkpoint inhibitors (CPI), targeting, for example, cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) or programmed cell death protein (PD-1). TThe combination of these therapies (anti-PD-1 with anti-CTLA-4) induces high response rates, and seem to be increased further when applied in early-stage disease. However, combined CTLA-4 plus PD-1 blockade causes frequent high-grade immune-related adverse events (irAE). To date, research on biological mechanism of irAEs is scarce and no widely accepted biomarkers predicting onset of severe irAEs have been identified. The similarity of irAEs to autoimmune disorders fuels the hypothesis that irAEs may be linked to susceptible genetic loci related to various autoimmune diseases. In this review, we extensively searched for susceptible loci associated with various autoimmune diseases, and pooled them in groups most likely to be associated with CPI-induced irAEs. These sets could be used in future research on predicting irAEs and guide physicians in a more refined and personal manner.

Correlation between CTLA4 genetic polymorphisms, its serum protein level and the susceptibility to recurrent spontaneous abortion: A case-control study

Present study was aimed to detect the influence of cytotoxic T-lymphocyte associated protein 4 (CTLA4) gene polymorphisms for the risk of recurrent spontaneous abortion (RSA), as well as the serum level of CTLA4 protein in RSA patients.One hundred thirty-three RSA patients and 146 healthy persons were recruited in this case-control study. PCR-RFLP was used to genotype the CTLA4 gene polymorphisms both in case and control groups. Serum level of CTLA4 was detected by ELISA kit. Quantitative variables were compared by t test or Mann-Whitney U test between groups. Qualitative variables were evaluated by χ test or Fisher exact test. Association strength was expressed by odds ratios (ORs) and 95% confidence intervals (95% CIs).G allele of rs4553808 (P = .027, OR = 0.570, 95% CI = 0.345-0.942) and T allele of rs5742909 (P = .027, OR = 0.570, 95% CI = 0.345-0.942) were distinctly associated with reduced susceptibility of RSA. Distinctly negative association has been discovered between rs231775 AA genotype and RSA susceptibility (P = .040, OR = 0.427, 95% CI = 0.188-0.973). CTLA4 protein had significantly higher serum level in RSA patients than in healthy controls (P = .028). In RSA patients, AA genotype carriers had higher CTLA4 serum level than that GG genotype carriers (17.83 ± 6.35 ng/mL vs 10.41 ± 7.28 ng/mL, P = .039).Minor alleles of CTLA4 polymorphisms might inhibit the RSA susceptibility via upregulated the protein expression level.

Juvenile-onset myasthenia gravis: autoantibody status, clinical characteristics and genetic polymorphisms

Myasthenia gravis (MG) is an autoimmune disorder mediated by antibodies against proteins at the neuromuscular junction. Juvenile-onset MG (JMG) has been reported to have special characteristics. It is still unclear whether there are any pathogenic and genetic differences between juvenile and adult MG. In this study, we evaluated the clinical characteristics, autoantibody status (antibodies against AChR, MuSK, LRP4, titin and RyR) and genetic susceptibility (CHRNA1, CTLA4 and AIRE) in 114 Chinese JMG patients, and compared with 207 young adult MG patients (onset age 18-40 years). JMG patients were classified into two subgroups: the very early onset group (<8 years) and puberty onset group (8-18 years). The very early onset MG patients had a higher proportion of ocular MG and thymus hyperplasia, compared with puberty onset MG and young adult MG (P < 0.05). AChR antibodies were found in majority of JMG patients and were associated with more severe disease (P < 0.05), while other antibodies were rare in JMG. Moreover, the very early onset MG had a more prominent genetic predisposition than puberty and adult MG, affecting the susceptible genes CHRNA1 and CTLA4. JMG has the same pathogenic background as adult MG, but has typical clinical features and a prominent genetic predisposition in very early onset patients (<8 years). Specific therapeutic considerations are needed.