Association analysis with microsatellite and SNP markers does not support the involvement of BCL-2 in systemic lupus erythematosus in Mexican and Swedish patients and their families

Association of BCL2 polymorphisms and the IL19 single nucleotide polymorphism rs2243188 with systemic lupus erythematosus

Objective

Abnormal B cell lymphoma-2 (Bcl-2) and interleukin-19 (IL-19) expression is closely related to systemic lupus erythematosus (SLE) pathogenesis. We aimed to determine whether BCL2 polymorphisms and a single nucleotide polymorphism (SNP) of IL19 are significantly associated with SLE susceptibility and if this is affected by synergism between IL19 and BCL2 genotypes.

Methods

This observational cohort study randomly enrolled 150 patients with SLE and 150 healthy controls. Major BCL2 and IL19 allele and genotype distributions were examined in the two groups. The IL19 SNP rs2243188 was determined using the TaqMan-MGB probe method. The synergistic effect between BCL2 and IL19 and clinical symptoms of SLE was also analyzed.

Results

The distribution of major BCL2 genotypes and common BCL2 alleles, especially for genotypes 191, 193, and 197, differed significantly between patients and controls. A significant difference in the dominant genetic model was also observed between groups, but not in the recessive model. The risk of disease in individuals who carried both 195-bp BCL2 and 138-bp IL19 susceptibility alleles was higher than in those carrying either allele alone.

Conclusions

This preliminary study suggested that BCL2 polymorphisms and the IL19 SNP rs2243188 are closely related to the pathogenesis of SLE.

Evaluation of polymorphic variants in apoptotic genes and their role in susceptibility and clinical progression to systemic lupus erythematosus

Background Systemic lupus erythematosus (SLE) is an autoimmune disease marked by the disruption of the immune homeostasis. Patients exhibit a wide range of clinical manifestations, and environmental and genetic factors are involved in SLE pathogenesis. Evidence suggests that abnormalities in the cellular and molecular events that coordinate apoptosis may favour the generation of autoantigens involved in autoimmunity. In this way, the apoptotic deregulation may be affected by polymorphic variants in apoptotic-related genes. Methods We analyzed FAS, FASL, BCL-2 and BAX polymorphisms in order to correlate to SLE susceptibility and clinical features. A total of 427 SLE patients from the Hospital de Clínicas de Porto Alegre and 543 controls from southern Brazil were evaluated. Results We observed higher frequencies of the FASL -844CC genotype and -844C allele, as well as of the FASL-844C/IVS2nt-124A haplotype in African-derived SLE patients when compared to controls ( P < 0.001). FASL -844C, which is related to high FasL expression, could contribute to increased apoptosis and to the breakdown of immunological tolerance, favouring autoantibody production and inflammation. On the other hand, the BAX -248GA genotype and the -248A allele , related to low protein expression, were observed as a protective factor against SLE in this same population. The rate of apoptosis and cell death was evaluated in peripheral lymphocytes, and SLE patients presented a higher percentage of dead lymphocytes (CD3⁺Annexin V⁺ 7-AAD⁺) compared to the control group. Conclusion Our data support a role for apoptosis in SLE susceptibility.

Does HCV Patients Who Have BCL2 43Ala Genotype and Normal GH1 Levels Can Achieve Response to IFN Based Therapy?

The main objective of the current study is to examine the role of the statistical relation between BCL2 gene (Ala43Thr) single nucleotide polymorphism and growth hormone (GH1) levels in Egyptian HCV genotype-4 patients before and after treatment with pegylated interferon plus ribavirin. Eighty patients with HCV genotype-4 and 40 healthy volunteers as controls were enrolled in the prospective study. Gene polymorphism of BCL2 (Ala43Thr) using PCR-RFLP technique and GH1 concentrations using ELISA procedure were measured for all patients and controls. The present study resulted that Responder HCV genotype-4 Patients, with BCL2 43Ala genotype, have high significant increase in pre-treatment GH1 levels (>1 ng/ml); which represent normal levels, as compared to non-responders pre-treatment GH1 levels (<1 ng/ml); which represent low concentrations. We concluded that HCV genotype-4 patients who have normal GH1 concentrations and BCL-2 43Ala genotype can successfully achieve response to interferon based therapy.

Genetic variation in BCL-2 and response to interferon in hepatitis C virus type 4 patients

The prevalence of hepatitis C virus (HCV) infection varies across the world, with the highest number of infections reported in Egypt. BCL-2 gene polymorphism at codon 43 (127G/A) has been found to be a reliable and sensitive marker for the prediction of response to interferon therapy during viral infections. This study examined the correlation of BCL-2 gene polymorphism with the response to treatment with pegylated-IFN-alfa2b and ribavirin. Eighty patients with type 4 HCV and 40 healthy volunteers as controls were enrolled in a prospective study. Quantification of HCV-RNA by real-time PCR was performed for every patient, and gene polymorphism of BCL-2 (ala 43 Thr) was performed for all patients and controls. There was a statistically significant difference between non-responder patients and control group as regards the 43 Thr genotype and allele (P<0.05). Also, there was a statistically significant difference between responders and non-responders (P<0.05) as regards 43 Thr genotype and alleles. We conclude that BCL-2 gene polymorphism at codon 43 (127G/A) is a new biological marker to potentially identify responders and non-responders of HCV genotype 4 patients to achieving a sustained virological response to treatment with IFN in combination with ribavirin.

IL-10 and TNFalpha genotypes in SLE

The production of two regulators of the inflammatory response, interleukin 10 (IL-10) and tumor necrosis factor α (TNFα), has been found to be deeply deregulated in SLE patients, suggesting that these cytokines may be involved in the pathogenesis of the disease. Genetic polymorphisms at the promoter regions of IL-10 and TNFα genes have been associated with different constitutive and induced cytokine production. Given that individual steady-state levels of these molecules may deviate an initial immune response towards different forms of lymphocyte activation, functional genetic variants in their promoters could influence the development of SLE. The present review summarizes the information previously reported about the involvement of IL-10 and TNFα genetic variants on SLE appearance, clinical phenotype, and outcome. We show that, in spite of the heterogeneity of the populations studied, the existing knowledge points towards a relevant role of IL-10 and TNFα genotypes in SLE.

Bcl-2-regulated cell death signalling in the prevention of autoimmunity

Cell death mediated through the intrinsic, Bcl-2-regulated mitochondrial apoptosis signalling pathway is critical for lymphocyte development and the establishment of central and maintenance of peripheral tolerance. Defects in Bcl-2-regulated cell death signalling have been reported to cause or correlate with autoimmunity in mice and men. This review focuses on the role of Bcl-2 family proteins implicated in the development of autoimmune disorders and their potential as targets for therapeutic intervention.

Overexpression of the antiapoptotic gene Bfl-1 in B cells from patients with familial systemic lupus erythematosus

Genetic determinants taking part in the development of systemic lupus erythematosus (SLE) are complex and not fully characterized. Dysregulated expression of genes involved in the control of apoptosis has been previously suggested. We report here a consanguineous family with SLE manifestations in three siblings associated in one of them with severe lymphoproliferative features. Laboratory studies showed no defect in CD95-mediated cell death. Screening expression of Bcl-2 family genes that regulate mitochondrial apoptosis pathway showed an overexpression of the antiapoptotic Bfl-1 gene. Real time RT-PCR analysis indicated that overexpression of Bfl-1 was restricted to B-cells, with normal expression in T-cells. Those results suggest that overexpression of Bfl-1 could result in impaired B-lymphocyte homeostasis and inappropriate immune response leading to autoimmune manifestations.

Evidence for linkage and association between autoimmune thyroid diseases and the 18q12-q21 region in a large Tunisian family

Many studies have shown linkage between IDDM6 locus on 18q12-q21 chromosome and several autoimmune diseases, suggesting that it might harbour susceptibility genes common to autoimmunity. Using 12 families deriving from a large Tunisian multiplex family (the Akr family) from which 38 people were affected with autoimmune thyroid diseases (AITD), and 193 unrelated AITD patients, tested against 100 healthy subjects, we tried to replicate the positive results previously reported for the IDDM6. Akr members were genotyped with eight microsatellite markers harbouring the IDDM6 region. Multipoint non-parametric linkage analysis have shown a clear peak values of NPL score around D18S41 marker (Z = 3.72, P = 0.0001). Family-based association test (FBAT) and transmission disequilibrium test (TDT) have confirmed linkage results. In particular, a significant association with allele 3 of D18S41 and allele 2 of D18S57 markers was found. Case-control studies, using one intragenic microsatellite (locus CTG18.1) marker in the immunoglobulin transcription factor (ITF2) gene, a 5' flanking AC repeat of the anti-apoptotic BCL-2 gene as well as two SNPs at positions +52 and +1955 from transcription start site of BCL-2, showed no significant association between neither genes and AITD. Our study is the first replication of the 18q12-q21 chromosome region as a potential candidate to AITD genetic susceptibility. The Akr family has shown evidence for linkage between IDDM6 locus and AITD. Moreover, case-control study does not support the involvement of ITF2 and BCL2 genes in AITD pathogenesis.

Sex hormones and SLE: influencing the fate of autoreactive B cells

The prevalence of systemic lupus erythematosus (SLE) is far higher in females than in males and numerous investigations to understand this gender bias have been conducted. While it is plausible that some sex-linked genes may contribute to the genetic predisposition for the disease, other likely culprits are the sex hormones estrogen and prolactin. In this chapter we review studies that have addressed the influence of sex hormones in SLE activity and discuss the recent data established in a BALB/c mouse transgenic for the heavy chain of an anti-DNA antibody. These mice are prone to develop lupus following exposure to exogenous sex hormones. We describe how estrogen and prolactin influence B cell maturation and selection, permitting B cells to mature to immunocompetence. Finally, we discuss the relevance and implications of these data for human disease.

Genetics of systemic lupus erythematosus: how far have we come?

There are two primary mechanisms for studying the genetic forces at work in systemic lupus erythematosus (SLE). Several groups have collected large numbers of pedigrees in which multiple family members have SLE for use in linkage studies. These linkage studies serve to isolate areas of the genome in which susceptibility genes lie. Other groups have taken a more direct approach of investigating genes that might contribute to disease pathogenesis in sets of lupus subjects and matched controls. These association studies are accumulating in greater numbers as the technology to determine the genotype at a given locus becomes more accessible. This article discusses the results of both types of studies.

Genetics of lupus nephritis

Susceptibility to lupus nephritis is the end-result of complex interactions between polymorphic genetic factors involved in the regulation of immune responses. In humans, genome-wide screens and candidate-gene analyses led to the identification of several loci containing potential targets (FcgammaRIIa, PTPN22, PD-1, IL-10) for physiopathological research and therapeutic interventions. In mice, the generation of congenic mice, bearing in a normal genetic background one single disease-associated locus, greatly improved our understanding of the mechanisms mediating the genetic contribution to the disease. In the future, the identification of disease-associated genes will open new perspectives for the development of more targeted therapies of lupus nephritis.

Differential effect of IL10 and TNF{alpha} genotypes on determining susceptibility to discoid and systemic lupus erythematosus

OBJECTIVE

To ascertain the possible involvement of functional interleukin 10 (IL10) and tumour necrosis alpha (TNFalpha) cytokine promoter polymorphisms on the susceptibility to discoid and systemic lupus erythematosus (DLE, SLE), and their associations with immunological features.

METHODS

Single nucleotide polymorphisms of the IL10 (-1082, -819, and -592) and TNFalpha (-308) genes were determined using allele specific probes in 248 lupus patients and 343 matched controls. To assess functional significance of genotypes, basal mRNA cytokine levels were quantified in 106 genotyped healthy controls by real time RT-PCR. Specific autoantibodies and cutaneous manifestations were analysed in SLE patients and associated with functional genotypes.

RESULTS

After analysing the distribution of IL10 and TNFalpha transcript levels according to promoter genotypes in healthy individuals, patients and controls were classified into functional single and combined genotypes according to the expected high or low constitutive cytokine production. High TNFalpha genotypes (-308AA or AG) were associated with SLE independently of IL10 alleles, whereas the risk of developing DLE and the prevalence of discoid lesion in SLE were higher in the high IL10/low TNFalpha producer group (-1082GG/-308GG). Cytokine interaction also influences the appearance of autoantibodies. Antibodies against Sm are prevalent among low producer patients for both cytokines, a genotype not associated with lupus incidence, whereas low IL10/high TNFalpha patients have the highest frequency of antibodies to SSa and SSb.

CONCLUSIONS

IL10/TNFalpha interaction influences susceptibility to DLE and the appearance of specific autoantibodies in SLE patients, whereas high TNFalpha producer genotypes represent a significant risk factor for SLE.

The role of interleukin-10 in autoimmune disease: systemic lupus erythematosus (SLE) and multiple sclerosis (MS)

Interleukin-10 (IL-10) is an immunoregulatory cytokine that plays a crucial role in inflammatory and immune reactions. It has potent anti-inflammatory and immunosuppressive activities on myeloid cell functions which forms a solid basis for its use in acute and chronic inflammatory diseases. Here, we discuss the role of IL-10 in autoimmune diseases and examine its beneficial effects in cellular-based autoimmune diseases such as multiple sclerosis (MS) or its involvement in humoral-based autoimmune diseases such as systemic lupus erythematosus (SLE). Inhibition of the immune stimulatory activities of IL-10 may provide novel approaches in the treatment of humoral autoimmune diseases, infectious diseases and cancer.

No evidence of a functionally significant polymorphism of the BCL2 gene in Danish, Finnish and Basque type 1 diabetes families

Accumulating evidence has suggested a role for the anti-apoptotic protein BCL2 in the development of autoimmune diseases, including type 1 diabetes mellitus (T1DM). Recently, the first BCL2 polymorphism (Ala43Thr) with association to T1DM in a Japanese population was reported. The polymorphism was found significantly more frequent in control individuals (14.5%) than in T1DM patients (6.8%), and was furthermore found to be functionally relevant, promoting a increased sensitivity to apoptosis when overexpressed in an IL-7 dependent mouse pre-B cell line. To investigate the relevance of the polymorphism in Caucasians, we have genotyped nearly 1400 individuals comprising Danish, Finnish and Basque T1DM family materials, using a PCR-based RFLP assay. In contrast to what was observed in Japanese diabetic/control individuals, we find no evidence for association of the BCL2 Ala43Thr polymorphism to T1DM in Danish, Finnish and Basque Type 1 diabetes families.