Immunoglobulin KM genes in Guillain-Barré syndrome

Genetic basis of Guillain-Barre syndrome

Guillain-Barré syndrome (GBS) is an autoimmune disease in which the peripheral nerves are affected. GBS has different subtypes, such as acute inflammatory demyelinating polyneuropathy (AIDP) and acute motor axonal neuropathy (AMAN). Infections, e.g. Campylobacter jejuni, influenza, etc., can lead to GBS. Both environmental and genetic factors play a major role in the occurrence of GBS. Several studies have investigated the genetic basis of GBS. Human leukocyte antigens (HLA) genes, Cluster of Differentiation (CD) 1A, FAS, Fc gamma receptors (FcGR), Intercellular adhesion molecule-1 (ICAM1), different interleukins, Nucleotide oligomerization domain (NOD), Toll-like receptor 4 (TLR4), Tumor necrosis factor-α (TNF-α) are among the genes reported to be involved in susceptibility to the disease. Dysregulation and dysfunction of the mentioned gene products, even though their role in the pathogenesis of GBS is controversial, play a role in inflammatory pathways, regulation of immune cells and system, antigen presentation, axonal degeneration, apoptosis, and cross-reaction. This review aims to summarize associated genes with GBS to contribute to better understanding of GBS pathogenesis and discover the gene pathways that play role in GBS occurrence.

Genetic polymorphisms in Guillain-Barré Syndrome: A field synopsis and systematic meta-analysis

OBJECTIVE

Guillain-Barré Syndrome (GBS) is considered to be a complex immune-mediated neuropathy. In the past few years, numerous studies were performed to detect the association between genetic polymorphisms and GBS risk. However, the findings of these studies were controversial. Thus, we conducted this field synopsis and systematic meta-analysis for further evaluating the possible associations between all available genetic polymorphisms and GBS susceptibility.

METHODS

Relevant studies focusing on the association between all genetic polymorphisms and GBS risk were obtained by a comprehensive literature search. The pooled odds ratios (ORs) as well as 95% confidence intervals (CIs) were used for assessing the strength of association. Subgroup analyses stratified by ethnicity and GBS subtype were further performed. Moreover, sensitive analysis and publication bias were conducted for evaluating the reliability of the results.

RESULTS

Among the initial identified 333 articles, 41 articles reporting on 220 genetic polymorphisms were extracted for conducting this systematic review. Then, we performed 95 primary and 94 subgroup meta-analyses for 59 variants with at least three independent studies available. The results showed significant association between four variants (FcγR IIA rs1801274, TNF-α rs1800629, HLA DRB1*0401 and HLA DRB1*1301) and GBS susceptibility. In the subgroup analysis, three (TNF-α rs1800629, TNF-α rs1800630 and TLR4 rs4986790) and two (FcγR IIA rs1801274, HLA DRB1*14) variants showed association with increased GBS risk in Asian and Caucasian population, respectively. Also, TNF-α rs1800629 was significant associated with AMAN subtypes of GBS. Furthermore, sensitivity analysis, funnel plots and Egger's test displayed robust results, except for FcγR IIA rs1801274. Additionally, for 161 variants with less than three studies, 17 genetic variants have been found to be significantly related with GBS risk in our systematic review.

INTERPRETATION

In our study, we assessed the association between all available genetic polymorphisms and GBS susceptibility. We hope our findings would be helpful for identifying novel genetic biomarkers and potential therapeutic targets for GBS.

Role of cytokines and Toll-like receptors in the immunopathogenesis of Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) is an autoimmune disease of the peripheral nervous system, mostly triggered by an aberrant immune response to an infectious pathogen. Although several infections have been implicated in the pathogenesis of GBS, not all such infected individuals develop this disease. Moreover, infection with a single agent might also lead to different subtypes of GBS emphasizing the role of host factors in the development of GBS. The host factors regulate a broad range of inflammatory processes that are involved in the pathogenesis of autoimmune diseases including GBS. Evidences suggest that systemically and locally released cytokines and their involvement in immune-mediated demyelination and axonal damage of peripheral nerves are important in the pathogenesis of GBS. Toll-like receptors (TLRs) link innate and adaptive immunity through transcription of several proinflammatory cytokines. TLR genes may increase susceptibility to microbial infections; an attenuated immune response towards antigen and downregulation of cytokines occurs due to mutation in the gene. Herein, we discuss the crucial role of host factors such as cytokines and TLRs that activate the immune response and are involved in the pathogenesis of the disease.

Familial Guillain-Barré syndrome: First Indian report

Guillain-Barré syndrome (GBS) is the commonest acute immune-mediated peripheral neuropathy. Specific human leukocyte antigen types have been found in patients with axonal and demyelinating subtypes of GBS suggesting genetic susceptibility in the generation of GBS. However, familial occurrence of GBS is rare and 42 patients from 20 families have been reported. Majority of them are from European countries and two families have been documented from Asian countries, while none have been reported from India. Electrophysiological characterization in familial GBS has been limited. We report the clinical and detailed electrophysiological findings in two affected brothers with familial GBS from India who had GBS five years apart. Both of them had mixed axonal and demyelinating features in nerve conductions and had complete clinical recovery. Our report documents the first Indian familial occurrence of GBS. Detailed genetic and epidemiological studies are required to find the true prevalence of familial GBS.

The effect of TNF-alpha, FcγR and CD1 polymorphisms on Guillain-Barré syndrome risk: evidences from a meta-analysis

BACKGROUND AND OBJECTIVES

The findings on the associations between potential genetic variants and risk of Guillain-Barré syndrome (GBS) are controversial. We conducted a meta-analysis for candidate genes to provide the evidences for the current understanding of the genetic association with GBS.

METHODS

We searched relevant studies without language restriction in PubMed, Embase and Cochrane library through May 2011. The strengths of the associations between genetic variants and GBS risk were estimated by odds ratios (ORs) with 95% confidence intervals (CIs). Random-effects models or fixed effects model was applied based on the heterogeneity test.

RESULTS

We identified 12 case-control studies involving 1,590 GBS cases and 2,154 controls for the analysis. Because of limited eligible data, our meta-analysis specifically focused on 6 genetic variants of 3 candidate genes, TNF-α, FcγR and CD1. We found that TNF-α 308 G/A polymorphism was significantly associated with the risk of GBS in the overall population (GG+GA vs. AA: OR=0.32, 95%CI=0.16-0.62; GG vs. AA: OR=0.36, 95%CI=0.19-0.68). Subgroup analysis further provided evidence of significant association between TNF-α 308 G/A and risk of the GBS in Asian population (GG+GA vs. AA: OR=32, 95%CI=0.11-0.93; GG vs. AA: OR=0.32, 95%CI=0.15-0.68). In addition, we did not observe significant associations between FcγRIIA R/H, FcγRIIIA F/V, FcγRIIIB NA1/NA2, CD1A 1/2 and CD1E 1/2 polymorphisms and susceptibility for developing GBS.

CONCLUSIONS

Our findings showed that TNF-α 308A allele might be a moderate risk factor for GBS. However, the results should be interpreted with caution due to the limited number of studies available.

Immunoglobulin GM and KM allotypes and prevalence of anti-LKM1 autoantibodies in patients with hepatitis C virus infection

GM and KM allotypes-genetic markers of immunoglobulin (Ig) gamma and kappa chains, respectively-are associated with humoral immunity to several infection- and autoimmunity-related epitopes. We hypothesized that GM and KM allotypes contribute to the generation of autoantibodies to liver/kidney microsomal antigen 1 (LKM1) in hepatitis C virus (HCV)-infected persons. To test this hypothesis, we characterized 129 persons with persistent HCV infection for several GM and KM markers and for anti-LKM1 antibodies. The heterozygous GM 1,3,17 23 5,13,21 phenotype was significantly associated with the prevalence of anti-LKM1 antibodies (odds ratio, 5.13; P=0.002), suggesting its involvement in this autoimmune phenomenon in HCV infection.

Immunoglobulin KM allotypes are associated with the prevalence of autoantibodies to GD1a ganglioside, but not with susceptibility to the disease, in Japanese patients with Guillain–Barré syndrome

Guillain-Barré syndrome (GBS), an autoimmune disease of the peripheral nervous system, is associated with antecedent Campylobacter jejuni infection. GM and KM allotypes--genetic markers of immunoglobulin gamma and kappa chains, respectively--are implicated in the etiopathogenesis of several autoimmune diseases. To determine if GM/KM phenotypes are associated with GBS and influence antibody responses to C. jejuni and to GM1 and GD1a gangliosides, 72 Japanese GBS patients and 73 controls were allotyped for several GM and KM markers. Sera from patients were characterized for antibodies to C. jejuni, GM1, and GD1a. The distribution of KM phenotypes was significantly different in patients with anti-GD1a ganglioside antibodies from those who lacked these antibodies (P=0.029). No other significant associations were found. These results suggest that KM allotypes are not risk factors for developing GBS, but contribute significantly to the generation of autoimmune responses to GD1a ganglioside in patients with this disease.

Functional polymorphisms in LPS receptors CD14 and TLR4 are not associated with disease susceptibility or Campylobacter jejuni infection in Guillain-Barré patients

Guillain-Barré syndrome (GBS) is an acute immune-mediated polyneuropathy preceded by infections. Campylobacter jejuni is the most frequent pathogen and its lipopolysaccharide (LPS) induces antibodies cross-reactive with gangliosides. In this study we assessed whether known functional polymorphisms in the LPS receptors CD14 and Toll-like receptor 4 (TLR4) are associated with an increased susceptibility for GBS or with C. jejuni serology or C. jejuni related clinical and serological features. Comparison of the genotypes of 242 GBS patients and 210 healthy subjects showed that polymorphisms in CD14 and TLR4 did not confer disease susceptibility and were not associated with C. jejuni infection.

Epistatic effects of genes encoding immunoglobulin GM allotypes and interleukin-6 on the production of autoantibodies to 60- and 65-kDa heat-shock proteins

Immunoglobulin GM and KM genes have been associated with antibody responses to a variety of antigens. A promoter-region polymorphism of interleukin-6 (IL-6) gene (-174 G/C) has been shown to be associated with antibody responses to heat-shock proteins (hsp) 60 and hsp65. To examine the possible epistatic effects of these unlinked genetic systems on the autoimmune responses to hsp60 and hsp65, 176 healthy Caucasian subjects from Finland were genotyped for several allelic determinants of GM, KM, and IL-6 genes by PCR-RFLP methods. IgG antibodies to hsp60 and hsp65 were measured by an ELISA. Significant interactive effects of GM f,z and IL-6-174 genotypes were noted for both anti-hsp60 (P=0.002) and anti-hsp65 (P=0.038) antibody levels. Since these autoantibodies have been implicated in susceptibility to coronary heart disease and carotid atherosclerosis, the associations reported here might be relevant to the etiology of these diseases.