The CTLA-4 gene polymorphisms are associated with CTLA-4 protein expression levels in multiple sclerosis patients and with susceptibility to disease

CCR5 Δ32 and CTLA-4 +49 A/G Gene Polymorphisms and Interferon-β Treatment Response in Croatian and Slovenian Multiple Sclerosis Patients

The aim of the present study was to investigate the impact of CCR5 Δ32 and CTLA-4 polymorphisms on the response to IFN-β treatment in our cohort of MS patients from Croatia and Slovenia. Genomic DNA was obtained from 295 MS patients (230 female; 65 male) classified as responders (n = 173) and non-responders (n = 122) based on clinical criteria for treatment efficacy. Genotyping was performed via PCR/PCR-RFLP. No significant differences in the genotype/allele frequencies of CCR5Δ32 and CTLA-4 +49 A/G were detected between male responders and non-responders. A significantly higher prevalence (p = 0.039) of the CTLA-4 +49 AA genotype was found in female responders (42.1%) compared to non-responders (28.9%). Using multiple forward regression analysis, the CTLA-4 +49 AA genotype significantly predicted a positive response to IFN-β therapy in females (p = 0.011) and contributed to 4.5% of response variability. Furthermore, the combined presence of the CCR5Δ32 wtwt/CTLA-4 +49 AA genotype significantly predicted a positive response to treatment in females (p = 0.025). The age at disease onset, pretreatment relapse rate, and baseline EDSS score were not reliable predictors of treatment response in MS patients. Our results indicate that the presence of the CCR5Δ32 polymorphism was not associated with the response to IFN-β treatment, whereas the CTLA-4 +49 polymorphism showed a positive correlation with an optimal response in female patients.

Advances in immune checkpoint-based immunotherapies for multiple sclerosis: rationale and practice

Beyond the encouraging results and broad clinical applicability of immune checkpoint (ICP) inhibitors in cancer therapy, ICP-based immunotherapies in the context of autoimmune disease, particularly multiple sclerosis (MS), have garnered considerable attention and hold great potential for developing effective therapeutic strategies. Given the well-established immunoregulatory role of ICPs in maintaining a balance between stimulatory and inhibitory signaling pathways to promote immune tolerance to self-antigens, a dysregulated expression pattern of ICPs has been observed in a significant proportion of patients with MS and its animal model called experimental autoimmune encephalomyelitis (EAE), which is associated with autoreactivity towards myelin and neurodegeneration. Consequently, there is a rationale for developing immunotherapeutic strategies to induce inhibitory ICPs while suppressing stimulatory ICPs, including engineering immune cells to overexpress ligands for inhibitory ICP receptors, such as program death-1 (PD-1), or designing fusion proteins, namely abatacept, to bind and inhibit the co-stimulatory pathways involved in overactivated T-cell mediated autoimmunity, and other strategies that will be discussed in-depth in the current review. Video Abstract.

Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) as an undetermined tool in tumor cells

In the tumor microenvironment, the function of T cells is a fate-changer for tumor progression. In the meantime, CD28 and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) are vital role players in the controlling activity of T cells as an activator and deactivator, respectively. In T cells in comparison to CD28, the molecular mechanism of CTLA-4 is unclear. In addition, despite the fact that most tumor cell types express CTLA-4, its role in tumor cells is not well understood and only few studies focused on the role of CTLA-4 signaling in tumor cells. It is illustrated that CTLA-4 signaling causes PD-L1 expression in tumor cells. However, numerous characteristics of CTLA-4 signaling in tumor cells are ambiguous and require to be described. In this article, we proposed that the CTLA-4 signaling during immunotherapy with anti-CTLA-4 antibodies may cause poor responses by patients. In addition, we attract attention to several fundamental questions regarding CTLA-4 signaling in tumor cells. Overall, the CTLA-4 signaling function and the related gaps about its role in tumor cells in the present review are challenged.

Computational analysis of structural and functional evaluation of the deleterious missense variants in the human CTLA4 gene

CTLA-4 is an immune checkpoint receptor that negatively regulates the T-cell function expressed after T-cell activation to break the immune response. The current study predicted the genomic analysis to explore the functional variations of missense SNPs in the human CTLA4 gene using PolyPhen2, SIFT, PANTHER, PROVEAN, Fathmm, Mutation Assessor, PhD-SNP, SNPs&GO, SNAP2, and MutPred2. Phylogenetic conservation protein was predicted by ConSurf. Protein structural analysis was carried out by I-Mutant3, MUpro, iStable2, PremPS, and ERIS servers. Molecular dynamics trajectory analysis (RMSD, RMSF, Rg, SASA, H-bonds, and PCA) was performed to analyze the dynamic behavior of native and mutant CTLA-4 at the atomic level. Our in-silico analysis suggested that C58S, G118R, P137Q, P137R, P137L, P138T, and G146L variants were predicted to be the most deleterious missense variants and highly conserved residues. Moreover, the molecular dynamics analysis proposed a decrease in the protein stability and compactness with the P137R and P138T highlighting the impact of these variants on the function of the CTLA-4 protein.Communicated by Ramaswamy H. Sarma.

Can Soluble Immune Checkpoint Molecules on Exosomes Mediate Inflammation?

Immune checkpoints (ICPs) are major co-signaling pathways that trigger effector functions in immune cells, with isoforms that are either membrane bound, engaging in direct cell to cell activation locally, or soluble, acting at distant sites by circulating freely or potentially via extracellular vesicles (EVs). Exosomes are small EVs secreted by a variety of cells carrying various proteins and nucleic acids. They are distributed extensively through biological fluids and have major impacts on infectious diseases, cancer, and neuroinflammation. Similarly, ICPs play key roles in a variety of disease conditions and have been extensively utilized as a prognostic tool for various cancers. Herein, we explored if the association between exosomes and ICPs could be a significant contributor of inflammation, particularly in the setting of cancer, neuroinflammation and viral infections, wherein the up regulation in both exosomal proteins and ICPs correlate with immunosuppressive effects. The detailed literature review of existing data highlights the significance and complexity of these two important pathways in mediating cancer and potentiating neuroinflammation via modulating overall immune response. Cells increasingly secret exosomes in response to intracellular signals from invading pathogens or cancerous transformations. These exosomes can carry a variety of cargo including proteins, nucleic acids, cytokines, and receptors/ligands that have functional consequences on recipient cells. Illustration generated using BioRender software.

The Role of Cytotoxic T-Lymphocyte Antigen 4 in the Pathogenesis of Multiple Sclerosis

Multiple sclerosis (MS) is an autoimmune neurodegenerative disorder of the central nervous system that presents heterogeneous clinical manifestations and course. It has been shown that different immune checkpoints, including Cytotoxic T-Lymphocyte Antigen 4 (CTLA-4), can be involved in the pathogenesis of MS. CTLA-4 is a critical regulator of T-cell homeostasis and self-tolerance and represents a key inhibitor of autoimmunity. In this scopingreview, we resume the current preclinical and clinical studies investigating the role of CTLA-4 in MS with different approaches. While some of these studies assessed the expression levels of CTLA-4 on T cells by comparing MS patients with healthy controls, others focused on the evaluation of the effects of common MS therapies on CTLA-4 modulation or on the study of the CTLA-4 blockade or deficiency in experimental autoimmune encephalomyelitis models. Moreover, other studies in this field aimed to discover if the CTLA-4 gene might be involved in the predisposition to MS, whereas others evaluated the effects of treatment with CTLA4-Ig in MS. Although these results are of great interest, they are often conflicting. Therefore, further studies are needed to reveal the exact mechanisms underlying the action of a crucial immune checkpoint such as CTLA-4 in MS to identify novel immunotherapeutic strategies for MS patients.

Activation pathways that drive CD4+ T cells to break tolerance in autoimmune diseases. Immunol Rev 2022;307:161-190. [PMID: 35142369 PMCID: PMC9255211 DOI: 10.1111/imr.13071]

Autoimmune diseases are characterized by dysfunctional immune systems that misrecognize self as non-self and cause tissue destruction. Several cell types have been implicated in triggering and sustaining disease. Due to a strong association of major histocompatibility complex II (MHC-II) proteins with various autoimmune diseases, CD4+ T lymphocytes have been thoroughly investigated for their roles in dictating disease course. CD4+ T cell activation is a coordinated process that requires three distinct signals: Signal 1, which is mediated by antigen recognition on MHC-II molecules; Signal 2, which boosts signal 1 in a costimulatory manner; and Signal 3, which helps to differentiate the activated cells into functionally relevant subsets. These signals are disrupted during autoimmunity and prompt CD4+ T cells to break tolerance. Herein, we review our current understanding of how each of the three signals plays a role in three different autoimmune diseases and highlight the genetic polymorphisms that predispose individuals to autoimmunity. We also discuss the drawbacks of existing therapies and how they can be addressed to achieve lasting tolerance in patients.

Regulation of CTLA-4 and PD-L1 Expression in Relapsing-Remitting Multiple Sclerosis Patients after Treatment with Fingolimod, IFNβ-1α, Glatiramer Acetate, and Dimethyl Fumarate Drugs

Multiple sclerosis (MS) is a chronic demyelinating disease of the central nervous system (CNS) that is characterized by inflammation which typically results in significant impairment in most patients. Immune checkpoints act as co-stimulatory and co-inhibitory molecules and play a fundamental role in keeping the equilibrium of the immune system. Cytotoxic T-lymphocyte antigen-4 (CTLA-4) and Programmed death-ligand 1 (PD-L1), as inhibitory immune checkpoints, participate in terminating the development of numerous autoimmune diseases, including MS. We assessed the CTLA-4 and PD-L1 gene expression in the different cell types of peripheral blood mononuclear cells of MS patients using single-cell RNA-seq data. Additionally, this study outlines how CTLA-4 and PD-L1 expression was altered in the PBMC samples of relapsing-remitting multiple sclerosis (RRMS) patients compared to the healthy group. Finally, it investigates the impact of various MS-related treatments in the CTLA-4 and PD-L1 expression to restrain autoreactive T cells and stop the development of MS autoimmunity.

Cytotoxic T Lymphocyte Antigen 4 Gene +49 A/G (rs231775) Polymorphism and Susceptibility to Systemic Lupus Erythematosus

AIM

To assess the probable role of +49AG polymorphism in susceptibility to SLE in an Egyptian population.

BACKGROUND

Systemic lupus erythematosus (SLE) is a compound inflammatory chronic disease distinguished through the release of autoantibodies. Cytotoxic T lymphocyte associated antigen-4 is a main down controller of T-cell response; its dysregulation could affect SLE pathogenesis by altered T cells activation to self-antigens.

OBJECTIVES

To evaluate the CTLA-4 +49AG allelic and genotype frequency in a sample of the Egyptian population and correlate them with disease susceptibility and clinical severity.

MATERIALS AND METHODS

Including 100 patients with SLE and 100 healthy controls (age and gender matched), CTLA-4 exon 1 49 A>G Genotyping was done using Real-Time PCR.

RESULTS

No difference was noticed in genotype or allele distributions of the studied polymorphism between both groups. Similar genotypes and allele frequencies were established for the 2 groups after their stratification by the age of disease onset, clinical course, or severity.

CONCLUSION

CTLA-4 +49AG gene polymorphism is not linked with the liability to develop SLE in the studied Egyptian population. Yet it is significantly related to disease severity.

Genetic variants and risk of thyroid cancer among Iranian patients

The definition of an exclusive panel of genetic markers is of high importance to initially detect among this review population. Therefore, we gave a summary of each main genetic marker among Iranian patients with thyroid cancer for the first time which were classified based on their cellular function. Due to the results, a significant relationship was found between SNP in codons 194, 280, and 399 (XRCC1), Allele 3434Thr (XRCC7), GC or CC genotype 31, G/C (Survivin), 399G>A (XRCC1), Tru9I (vitamin D receptor), G-D haplotype (MDM2), TT genotype, -656 G/T (IL-18), TAGTT haplotype (IL-18), G allele in +49 A>G (CTLA-4), +7146 G/A (PD-1.3), +7785 C/T (PD-1.5), rs1143770 (let7a-2), rs4938723 (pri-mir-34b/c) genes, and thyroid cancers. Moreover, SNP in 677C-->T (MTHFR), GG genotype Asp1312Gly (thyroglobulin), 2259C>T (Rad52), R188H, (XRCC2), T241M (XRCC3) had higher risks of thyroid cancer and lower risks were observed in -16 Ins-Pro (p53), rs3742330 (DICER1). At last, the protective effects were explored in 127 CC genotype (IL-18), rs6877842 (DROSHA). Conduct further studies on the types of DNA repair gene polymorphisms with a larger number in the thyroid cancer using modern methods such as SNP array so that these genes could be used as a biomarker in prediction, diagnosis, and treatment of thyroid cancer. This review presents for the first time a summary of important genetic markers in Iranian patients with thyroid cancer.

Autoimmunity-Related Risk Variants in PTPN22 and CTLA4 Are Associated With ME/CFS With Infectious Onset

Single nucleotide polymorphisms (SNP) in various genes have been described to be associated with susceptibility to autoimmune disease. In this study, myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) patients and controls were genotyped for five immune gene SNPs in tyrosine phosphatase non-receptor type 22 (PTPN22, rs2476601), cytotoxic T-lymphocyte-associated protein 4 (CTLA4, rs3087243), tumor necrosis factor (TNF, rs1800629 and rs1799724), and interferon regulatory factor 5 (IRF5, rs3807306), which are among the most important risk variants for autoimmune diseases. Analysis of 305 ME/CFS patients and 201 healthy controls showed significant associations of the PTPN22 rs2476601 and CTLA4 rs3087243 autoimmunity-risk alleles with ME/CFS. The associations were only found in ME/CFS patients, who reported an acute onset of disease with an infection (PTPN22 rs2476601: OR 1.63, CI 1.04–2.55, p = 0.016; CTLA4 rs3087243: OR 1.53, CI 1.17–2.03, p = 0.001), but not in ME/CFS patients without infection-triggered onset (PTPN22 rs2476601: OR 1.09, CI 0.56–2.14, p = 0.398; CTLA4 rs3087243: OR 0.89, CI 0.61–1.30, p = 0.268). This finding provides evidence that autoimmunity might play a role in ME/CFS with an infection-triggered onset. Both genes play a key role in regulating B and T cell activation.

Reduced GLP-1 response to a meal is associated with the CTLA4 rs3087243 G/G genotype

Although insulitis is the characteristic main feature of type 1 diabetes mellitus (T1DM), many aspects of β cell loss still remain elusive. Immune dysregulation and alterations in the dipeptidyl-peptidase-4-incretin system might have a role in disease development, but their connection is poorly understood. We assessed the associations of a few selected, immunologically relevant single nucleotide gene variants with the DPP-4-incretin system in individuals with T1DM and in healthy controls. Prandial plasma (total, active) GLP-1 levels, serum DPP-4 activity, CD25 and CTLA-4 expression of T cells and DPP4 rs6741949, CTLA4 rs3087243, CD25 rs61839660 and PTPN2 rs2476601 SNPs were assessed in 33 T1DM patients and 34 age-, gender-, BMI-matched non-diabetic controls without a family history of T1DM. CTLA-4 expression was lower in the Foxp3+CD25+ regulatory T cells from individuals homozygous for the CTLA4 rs3087243-G variant compared to those who carry an A allele. Prandial plasma total GLP-1 levels 45 min after a standardized meal were reduced in individuals homozygous for the CTLA4 rs3087243 G major allele compared to A allele carriers both in the entire study population (with statistical power over 90%) and within the T1DM group. Here we report for the first time a reduced total prandial GLP-1 plasma concentration in individuals with the CTLA4 rs3087243 G/G genotype. One may speculate that immune response-related L cell damage might possibly explain this novel association.

CTLA-4 Genetic Variants Predict Survival in Patients with Sepsis

Cytotoxic T lymphocyte-associated protein 4 (CTLA-4) is a coinhibitory checkpoint protein expressed on the surface of T cells. A recent study by our working group revealed that the rs231775 single nucleotide polymorphism (SNP) in the CTLA-4 gene was associated with the survival of patients with sepsis and served as an independent prognostic variable. To further investigate the impact of CTLA-4 genetic variants on sepsis survival, we examined the effect of two functional SNPs, CTLA-4 rs733618 and CTLA-4 rs3087243, and inferred haplotypes, on the survival of 644 prospectively enrolled septic patients. Kaplan⁻Meier survival analysis revealed significantly lower 90-day mortality for rs3087243 G allele carriers (n = 502) than for AA-homozygous (n = 142) patients (27.3% vs. 40.8%, p = 0.0024). Likewise, lower 90-day mortality was observed for TAA haplotype-negative patients (n = 197; compound rs733618 T/rs231775 A/rs3087243 A) than for patients carrying the TAA haplotype (n = 447; 24.4% vs. 32.9%, p = 0.0265). Carrying the rs3087243 G allele hazard ratio (HR): 0.667; 95% confidence interval (CI): 0.489⁻0.909; p = 0.0103) or not carrying the TAA haplotype (HR: 0.685; 95% CI: 0.491⁻0.956; p = 0.0262) remained significant covariates for 90-day survival in the multivariate Cox regression analysis and thus served as independent prognostic variables. In conclusion, our findings underscore the significance of CTLA-4 genetic variants as predictors of survival of patients with sepsis.

Association between CTLA-4 + 49A > G and - 318C > T single-nucleotide polymorphisms and susceptibility to thyroid neoplasm

PURPOSE

Cytotoxic T-Lymphocyte Antigen 4 (CTLA-4 or CD152) is among the immune checkpoint molecules and its abnormal expression in cancer predisposed individuals might make the person more susceptible to tumor initiation and progression. Considering the implication of single-nucleotide polymorphisms (SNPs) in CTLA-4 gene expression and probably protein function, one can assume the involvement of these SNPs in neoplastic diseases. rs5742909 ( - 318C > T) and rs231775 ( + 49 A > G) are among the most commonly studied SNPs and have been considered as genetic factors related to thyroid diseases. In this cross-sectional study, we aimed to elucidate the association between these SNPs and susceptibility to various types of thyroid cancers.

METHODS

We investigated the genetic polymorphisms of - 318C > T and + 49 A > G in the CTLA-4 gene by means of ARMS-PCR and RFLP-PCR, respectively, in 167 patients with thyroid carcinomas (papillary, follicular, and anaplastic). The results were then compared with a group of 100 age-sex matched healthy individuals.

RESULTS

A statistically significant association was observed between the presence of G allele in + 49 A > G locus and thyroid carcinoma, when comparing cases and controls (OR = 2.10; 95% CI = 1.35-3.28; P = 0.001) and the frequency of heterozygotes (AG) was higher than homozygotes for allele A (AA), in patients with and papillary thyroid carcinoma (PTC). Regarding Hashimoto's thyroiditis, the frequencies of A allele and AA genotype in PTC patients were higher than Hashimoto patients with no history of cancer (OR = 4.67, 95% CI = 2.70-8.08, P < 0.0001; and, OR = 4.68, 95% CI = 1.84-11.91, P = 0.0012; respectively). However; we observed no difference among allele/genotype frequencies in regards to locus - 318C > T.

CONCLUSION

In this study, we observed that G allele in + 49 A > G and possibly lower expression of mutated CTLA-4 molecule, is associated with higher susceptibility to thyroid carcinoma. Although the G allele frequency was higher in thyroid cancer patients, when justified for the presence of lymphocytic thyroiditis, the presence of A allele seemed to increase the odds for PTC in patients with Hashimoto's disease.

CTLA-4 Genetic Variants (rs11571317 and rs3087243): Role in Susceptibility and Progression of Breast Cancer

Background

Dysfunctional regulation at immune checkpoints may lead to escape of the tumor cells and gives a scope to set in the unresolved Breast cancer (BC). The major anti-tumor retort is cell-mediated response which involves T lymphocytes. CTLA-4 (Cytotoxic T lymphocyte associated protein-4) with immune suppressive function and tolerance is associated with various autoimmune diseases and cancers including BC. The present study deals with CTLA-4 gene selected polymorphisms (rs11571317 C/T and rs3087243G/A) to explore their relation with breast cancer susceptibility and progression in BC patients.

Methods

For the present case-control study, we recruited a total of 570 women which include breast cancer patients and healthy control women from south India. Blood samples were collected, genomic DNA was isolated and genotyped by using PCR-RFLP method, and the data were analysed through suitable statistics.

Results

We observed a significant association of rs11571317 with BC in our study group, where CC genotype showed a three-fold increased risk towards BC and CT genotype to be protective. In-silico analyses strengthened our observation revealing the abolition of SP1 binding site in the CTLA-4 promoter by the mutant allele T. The CTLA-4 rs3087243 polymorphism showed an association not with the susceptibility but towards the tumor progression, where GG genotype was coupled with reduced tumor growth (OR = 0.01) and GA (OR = 6.2), AA (OR = 3.4) with increased tumor growth. The T-G haplotype was found to confer protection against breast cancer risk while C-A (OR = 3.6) and T-A (OR = 15.8) haplotypes were associated with disease progression. In-silico analysis for rs3087243 revealed change in threshold values between reference and variant sequences.

Conclusion

The study suggests varied roles of different polymorphisms of CTLA-4 in the aetiopathogenesis of BC. Understanding the mechanism may help in the CTLA-4 based immunotherapy for BC.

CTLA-4 gene polymorphisms associate with efficacy of postoperative radioiodine-131 for differentiated thyroid carcinoma

AIM

To investigate the association of CTLA-4 polymorphisms with efficacy of postoperative radioiodine-131 (I-131) treatment for differentiated thyroid carcinoma (DTC).

METHODS

A total of 324 DTC patients and 350 healthy individuals were enrolled in our study. Patients received I-131 remnant ablation following surgical resection. Based on the treatment efficacy, patients were divided into the effective (n = 183) and ineffective groups (n = 141). CTLA-4 polymorphisms (+49A>G, CT60A>G and -318C>T) were genotyped by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

AG + AA genotype distribution and A allele frequency of +49A>G and CT60A>G polymorphisms were higher in the effective group than the ineffective group.

CONCLUSION

+49A>G and CT60A>G polymorphisms were associated with the efficacy of postoperative I-131 treatment for DTC; and they might be bioindicators related to the prognosis of I-131 treatment.

PD-1 gene polymorphic variation is linked with first symptom of disease and severity of relapsing-remitting form of MS

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system (CNS), where inflammation, demyelination together with the axonopathy are the cardinal features on pathologic ground, with a combined genetic and environmental background. The associations of PD-1 single nucleotide polymorphisms (SNPs): PD-1.3 (in intron 4), PD-1.5 and PD-1.9 (both in exon 5) with clinical manifestation of MS in 479 south Polish individuals including 203 MS patients were analyzed. Presence of PD-1.5T allele was linked with the first manifestations of disease: diplopia and pyramidal signs - favored pyramidal signs but protected against of diplopia development. Farther, PD-1.3G/PD-1.5C/PD-1.9C haplotype significantly favored whereas GTC protected against diplopia. Besides, GTT haplotype strongly favored non-severe RRMS outcome and ATC haplotype was specific only for these MS patients. Our population-based case-control study, investigating selected three PD-1 SNPs: PD-1.3, PD-1.5 and PD-1.9, revealed that polymorphic variation may be rather disease-modifying than MS risk factor.

Is the Genetic Background of Co-Stimulatory CD28/CTLA-4 Pathway the Risk Factor for Prostate Cancer?

The impairment of immunological surveillance caused by aberrant T cell activation can lead to an inadequate anti-tumor response. Therefore, deregulation in co-stimulatory pathway might be associated with cancer susceptibility. Here we undertook a prospective study to investigate whether genetic variations in gene encoding molecule CD28 and CTLA-4 playing pivotal role in regulating adoptive immune response can influence susceptibility to prostate cancer. Single nucleotide polymorphisms (SNPs) in CTLA-4 and CD28 genes were genotyped in 301 prostate cancer (PCa) patients and 301 controls. The distributions of the genotypes and haplotypes in the CTLA-4/CD28 SNPs were similar in both studied groups. However, the overrepresentation of carriers of CTLA-4c.49A>G[A] allele and carriers of CTLA-4g.319C>T[T] allele in PCa as compared to controls was observed (p = 0.082 and p = 0.13, respectively). The risk of disease was higher (OR 1.78) for carriers of both susceptibility alleles as compared to carriers of protective genotypes (p = 0.03). The CTLA-4c.49A>G and CTLA-4g.319C>T SNPs might be considered as low risk susceptibility locus for PCa.

CTLA4 and CD28 Gene Polymorphisms with Respect to Affective Symptom Domain in Schizophrenia

BACKGROUND

Accumulating evidence indicates that immune alterations in schizophrenia are due to genetic underpinnings. Here, we aimed at investigating whether polymorphisms in CTLA4 and CD28 genes, encoding molecules that regulate T-cell activity, influence schizophrenia symptomatology.

METHOD

We recruited 120 schizophrenia patients and 380 healthy age- and sex-matched controls. We divided the patients into two groups: one with no co-occurrence between psychotic and affective symptoms and the second one with psychotic symptoms dominating in the clinical manifestation, although also with occasional affective disturbances in the course of illness.

RESULTS

Among the patients with co-occurring affective symptoms, there were significantly more CTLA4 c.49A>G[A] alleles (p = 0.018, odds ratio (OR) 2.03, 95% confidence interval (CI) 1.2-3.66) and more CTLA4 g.319C>T[T] alleles (p = 0.07, OR 1.93, 95% CI 0.94-4.13) in comparison to the second group. Additionally, we have shown that CD28 c.17 + 3T>C[C+] were more significantly overrepresented among patients with co-occurring psychotic and affective symptoms (p = 0.0003, OR 3.36, 95% CI 1.69-6.68) than in patients without co-occurence between these symptoms (p = 0.012, OR 1.88, 95% CI 1.15-3.10).

CONCLUSION

CTLA4 and CD28 gene polymorphisms may not only act in immune deregulation observed in schizophrenia, but may also influence the course of the illness by modifying the susceptibility to the co-occurrence of psychotic and affective symptoms.

CTLA-4 and CD28 genes' polymorphisms and renal cell carcinoma susceptibility in the Polish population--a prospective study

Polymorphisms in co-stimulatory genes are associated with susceptibility to several malignances such as breast cancer, cervical cancer and chronic lymphocytic leukemia, but have been scarcely investigated in renal cell cancer (RCC). A total of 310 RCC patients and 518 controls were genotyped for single-nucleotide polymorphisms (SNPs) in the CTLA-4 and CD28 genes: CTLA-4c.49A>G (rs231775), CTLA-4g.319C>T (rs5742909), CTLA-4g.*6230G>A (CT60; rs3087243), CTLA-4g.*10223G>T (Jo31; rs11571302), CD28c.17+3T>C (rs3116496) and CD28c.-1042G>A (rs3181098). The distribution of the alleles, genotypes and haplotypes in the CTLA-4 and CD28 genes were similar in the RCC patients and in the controls. However, among the patients with a clear cell RCC (CCRCC), the G allele carriers of CT60 and Jo31 SNPs were overrepresented, and the overrepresentation became significant for the carriers of CT60[G] allele in CCRCC patients with necrosis in the primary tumor (P = 0.046). The CTLA-4c.49A>G[A]/CTLA-4g.319C>T[C]/CT60[A]/Jo31[T]/CD28c.17+3T>C[T]/ CD28c.1042G>A[G] haplotype was associated with an approximately threefold increased risk of primary tumor necrosis in CCRCC patients (P corrected = 0.0000007) and with the advanced stage of disease (IV) (P corrected = 0.001). When stratified by gender, CD28c.-1042G>A[GG] genotype was more frequent in the female CCRCC patients compared with healthy women (P = 0.042). Polymorphisms in the CTLA-4 and CD28 genes, in particular considered together as haplotypes, were associated with increased risk of CCRCC, especially with necrosis and with the advanced stage of disease. The CD28c.-1042G>A SNP modulates the risk of CCRCC in women. These findings indicate that the associations of the CTLA-4 and CD28 polymorphisms with the risk of renal cancer are worth further study in a larger group of patients.

Study of association of CTLA4 gene variants to non-anterior uveitis

This study was undertaken to investigate the possible genetic association of functional CTLA4 polymorphisms with susceptibility to non-anterior uveitis. Four hundred and seventeen patients with endogenous non-anterior uveitis and 1517 healthy controls of Spanish Caucasian origin were genotyped for the CTLA4 polymorphisms rs733618, rs5742909 and rs231775, using predesigned TaqMan(©) allele discrimination assays. PLINK software was used for the statistical analyses. No significant associations between the CTLA4 polymorphisms and susceptibility to global non-anterior uveitis were found. It was also the case when the potential association of these genetic variants with the anatomical localization of the disease, such as intermediate, posterior or panuveitis, was assessed. Our results do not support a relevant role of these CTLA4 polymorphisms in the non-anterior uveitis genetic predisposition.

A CT60G>A polymorphism in the CTLA-4 gene of the recipient may confer susceptibility to acute graft versus host disease after allogeneic hematopoietic stem cell transplantation

T cell activation plays a crucial role in the development of acute graft versus host disease (aGvHD). Cytotoxic T cell antigen-4 (CTLA-4) is a co-inhibitory molecule that negatively regulates T cell activation, differentiation, and proliferation. Single-nucleotide polymorphisms (SNPs) in CTLA-4 gene may affect its function. Inconsistent observations have been reported regarding the associations of CTLA-4 SNPs with complications after hematopoietic stem cell transplantation (HSCT). Moreover, the majority of the observations were focused on the donors' SNPs. Recently, a few studies have shown that recipients' genetic variations in the CTLA-4 gene might influence HSCT results. The aim of our study was to determine the influence of the CTLA-4 gene polymorphisms of the donors and the recipients on the outcome of HSCT. Altogether, 312 donor-recipient pairs were genotyped for the CTLA-4c.49A>G (rs231775) and CT60G>A (rs3087243) SNPs using the TaqMan®SNP Genotyping Assays. In this study, it was shown that the recipients' CT60G>A[GG] genotype, the myeloablative conditioning regimen, and HSCT from an unrelated donor were independent aGvHD risk factors (odds ratio (OR) 2.63, 95% confidence intervals (95% CI) 1.45-4.59, p = 0.001; OR 2.68, 95% CI 1.65-4.07, p = 0.00003; and OR 1.87, 95 % CI 1.02-3.24, p = 0.04, respectively). Moreover, haplotype analysis revealed that possessing allele A in both of the SNPs decreased the risk of aGvHD approximately 1.5-fold (RR 0.69, p = 0.008). Our data suggest that the CT60G>A[GG] genotype in the recipient has an impact on aGvHD development, especially in patients receiving transplants from unrelated donors together with the myeloablative conditioning regimen.

Immune checkpoints in central nervous system autoimmunity

A number of autoimmune diseases, including multiple sclerosis, are mediated by self-reactive T cells that have escaped the deletional mechanisms of central tolerance. Usually, these T cells are kept at bay through peripheral tolerance mechanisms, including regulation through coinhibitory receptors and suppression by regulatory T cells. However, if these mechanisms fail, self-reactive T cells are activated and autoimmune responses ensue. This review outlines how the coinhibitory receptors CTLA-4 (cytotoxic T-lymphocyte antigen-4), PD-1 (programed death-1), Tim-3 (T-cell immunoglobulin- and mucin domain-containing molecule 3), and TIGIT (T-cell immunoreceptor with immunoglobulin and ITIM domains) act at different checkpoints to inhibit autoreactive T cells and suppress the development of central nervous system autoimmunity. Loss of each of these receptors predisposes to autoimmunity, indicating a non-redundant role in maintaining peripheral tolerance. At the same time, their functional patterns seem to overlap to a large degree. Therefore, we propose that only the concerted action of a combination of inhibitory receptors is able to maintain peripheral tolerance and prevent autoimmunity.

Self-tolerance in multiple sclerosis

During the last decade, several defects in self-tolerance have been identified in multiple sclerosis. Dysfunction in central tolerance leads to the thymic output of antigen-specific T cells with T cell receptor alterations favouring autoimmune reactions. In addition, premature thymic involution results in a reduced export of naïve regulatory T cells, the fully suppressive clone. Alterations in peripheral tolerance concern costimulatory molecules as well as transcriptional and epigenetic mechanisms. Recent data underline the key role of regulatory T cells that suppress Th1 and Th17 effector cell responses and whose immunosuppressive activity is impaired in patients with multiple sclerosis. Those recent observations suggest that a defect in self-tolerance homeostasis might be the primary mover of multiple sclerosis leading to subsequent immune attacks, inflammation and neurodegeneration. The concept of multiple sclerosis as a consequence of the failure of central and peripheral tolerance mechanisms to maintain a self-tolerance state, particularly of regulatory T cells, may have therapeutic implications. Restoring normal thymic output and suppressive functions of regulatory T cells appears an appealing approach. Regulatory T cells suppress the general local immune response via bystander effects rather than through individual antigen-specific responses. Interestingly, the beneficial effects of currently approved immunomodulators (interferons β and glatiramer acetate) are associated with a restored regulatory T cell homeostasis. However, the feedback regulation between Th1 and Th17 effector cells and regulatory T cells is not so simple and tolerogenic mechanisms also involve other regulatory cells such as B cells, dendritic cells and CD56(bright) natural killer cells.

Association of polymorphisms in non-classic MHC genes with susceptibility to autoimmune hepatitis

BACKGROUND

Autoimmune hepatitis is a chronic, generally progressive inflammatory disorder of the liver, of which the cause is unclear. It was demonstrated that genetic factors are involved in its pathogenesis. Previous studies showed that human leukocyte antigen in the major histocompatibility complex (MHC) is associated with susceptibility to autoimmune hepatitis. Current genome scanning studies suggest that genes outside the MHC also play a critical role in autoimmune disorders. This article focuses on our current understanding of the polymorphisms of these genes and their roles in the pathogenesis of autoimmune hepatitis.

DATA SOURCES

Studies were identified by searching MEDLINE and PubMed for articles using the keywords autoimmune hepatitis, polymorphism, CTLA-4, Fas, TNF-alpha, TGF-beta1, TBX21 and VDR up to May 2011. Additional papers were identified by a manual search of the references from key articles.

RESULTS

According to the case-control studies on genetic polymorphisms, at least six genes (CTLA-4, Fas, TNF-alpha, TGF-beta1, TBX21 and VDR) are involved in autoimmune hepatitis besides HLA. So far, there has been no agreement about gene susceptibility and the actual clinical significance of these genes is still controversial.

CONCLUSION

Studies on gene polymorphisms outside the MHC and knowledge of genetic predispositions for autoimmune hepatitis may not only elucidate pathogenic mechanisms, but also provide new targets for therapy in the future.

Low expression and secretion of circulating soluble CTLA-4 in peripheral blood mononuclear cells and sera from type 1 diabetic children

BACKGROUND

High levels of soluble cytotoxic T-lymphocyte antigen 4 (soluble CTLA-4), an alternative splice form of the regulatory T-cell (Treg) associated CTLA-4 gene, have been associated with type 1 diabetes (T1D) and other autoimmune diseases, such as Grave's disease and myasthenia gravis. At the same time, studies have shown soluble CTLA-4 to inhibit T-cell activation through B7 binding. This study aimed to investigate the role of soluble CTLA-4 in relation to full-length CTLA-4 and other Treg-associated markers in T1D children and in individuals with high or low risk of developing the disease.

METHODS

T1D children were studied at 4 days, 1 and 2 years after diagnosis in comparison to individuals with high or low risk of developing the disease. Isolated peripheral blood mononuclear cells were stimulated with the T1D-associated glutamic acid decarboxylase 65 and phytohaemagglutinin. Subsequently, soluble CTLA-4, full-length CTLA-4, FOXP3 and TGF-β mRNA transcription were quantified and protein concentrations of soluble CTLA-4 were measured in culture supernatant and sera.

RESULTS AND CONCLUSIONS

Low protein concentrations of circulating soluble CTLA-4 and a positive correlation between soluble CTLA-4 mRNA and protein were seen in T1D, in parallel with a negative correlation in healthy subjects. Further, low levels of mitogen-induced soluble CTLA-4 were accompanied by low C-peptide levels. Interestingly, low mitogen-induced soluble CTLA-4 mRNA and low TGF-β mRNA expression were seen in high risk individuals, suggesting an alteration in activation and down-regulating immune mechanisms during the pre-diabetic phase.

Genetic polymorphisms and surface expression of CTLA-4 and PD-1 on T cells of silica-exposed workers

Exposure to silica dust has been examined as a possible risk factor for autoimmune diseases, including scleroderma, rheumatoid arthritis and systemic lupus erythematosus. Since CTLA-4 [CD152] and PD-1 [CD279] are important for the maintenance of peripheral tolerance by regulating T cell responsiveness, we evaluated the expression of these molecules on the surface of CD4 and CD8 T cells, as well as single nucleotide polymorphisms (SNP) in CTLA-4 and PDCD1 genes, of 70 silica-exposed workers and 30 non-exposed, age-, ethnically- and sex-matched controls. Expression of CTLA-4 was significantly (P<0.05) reduced in CD4 T cells of exposed individuals [median=0.1% and interquartile range, IQR 0.0-0.1% (exposed), median=0.20%, IQR 0.0-0.4% (control)]. Also the expression of PD-1 was significantly (P<0.0001) reduced in both CD4 [median=0.9%, IQR 0.4-2.3% (exposed), median=5.7%, IQR 1.4-13.3% (control)] and CD8 T cells [median=0.9%, IQR 0.3-1.9% (exposed), median=5.0%, IQR 3.4-8.9% (control)]. The study of polymorphisms demonstrated a lower frequency of the A allele in the analysis of the PD1.3 SNP in the exposed group, which might be associated with the lower expression of PD-1 on the surface of CD4 T cells. Our findings provide evidence for the association of silica exposure and the maintenance of self-tolerance, i.e., the susceptibility to autoimmune disorders.

Variations in suppressor molecule ctla-4 gene are related to susceptibility to multiple myeloma in a polish population

Various phenotype and functional T-cell abnormalities are observed in multiple myeloma (MM) patients. The aim of this study was to investigate the association between polymorphisms in the gene encoding cytotoxic T-lymphocyte antigen-4 (CTLA-4), a negative regulator of the T-lymphocyte immune response and susceptibility to multiple myeloma in a Polish population. Two hundred MM patients and 380 healthy subjects were genotyped for the following polymorphisms: CTLA-4c.49A>G, CTLA-4g.319C>T, CTLA-4g.*642AT(8_33), CT60 (CTLA-4g.*6230G>A), Jo31 (CTLA-4g.*10223G>T). Our study is the largest and most comprehensive evaluation to date of the association between genetic polymorphisms in the CTLA-4 molecule and multiple myeloma. It was found that CTLA-4c.49A>G[G], CT60[G], and Jo31[G] alleles were more frequently observed in MM patients than in controls (0.50 vs. 0.44, p = 0.03, 0.65 vs. 0.58, p = 0.04, and 0.63 vs. 0.57, p = 0.03, respectively). Moreover, the haplotype CTLA-4c.49A>G[G], CTLA-4g.319C>T[C], CTLA-4g.*642AT(8_33) [8], CT60[G], Jo31[G] including all susceptibility alleles increases the risk of MM about fourfold (OR: 3.79, 95%CI: 2.08–6.89, p = 0.00001). These findings indicate that genetic variations in the CTLA-4 gene play role in susceptibility to multiple myeloma and warrant further investigation through replication studies.

CTLA-4, CD28, and ICOS gene polymorphism associations with non-small-cell lung cancer

Polymorphisms in genes encoding CD28, ICOS, and CTLA-4 were demonstrated to be associated with susceptibility to malignancies. To the best of our knowledge, no study on this association has been performed in a Caucasian population for non-small-cell lung cancer (NSCLC). In the present work, we investigated the polymorphisms CTLA-4c.49A>G (rs231775), CTLA-4g.319C>T (rs5742909), CTLA-4g.*642AT(8_33), CTLA-4g.*6230G>A (CT60) (rs3087243), CTLA-4g.*10223G>T (Jo31) (rs11571302), CD28c.17+3T>C (rs3116496), and ICOSc.1554+4GT(8_15) in 208 NSCLC patients and 326 controls. The distributions of the allele and genotype were similar in both groups for CTLA-4, CD28, and ICOS gene polymorphisms. However, we noted a tendency toward overrepresentation of individuals possessing the CTLA-4c.49A>G[A] allele in NSCLC patients compared with controls (0.84 vs 0.79, p = 0.09). The association became significant compared with controls in women for the CTLA-4c.49A>G[A] allele and CTLA-4c.49A>G[AA] genotype (0.67 vs 0.54, p = 0.01, and 0.47 vs 0.30, p = 0.02; respectively). Moreover, the constellation of alleles CTLA-4c.49A>G[A]/CT60[G]/CD28c.17+3T>C[T]/ICOSc.1554+4GT(8_15)[>10] increased the risk of NSCLC about 2-fold (p = 0.002). The same constellation of alleles combined with smoking, CTLA-4g.319C>T[T], and ICOSc.1554+4GT(8_15)[>10] was associated with a decreased overall survival rate. In conclusion, the constellation of specific alleles in CTLA-4, CD28, and ICOS genes contributes to the susceptibility and clinical course of NSCLC.

Alternative splicing in multiple sclerosis and other autoimmune diseases

Alternative splicing is a general mechanism for regulating gene expression that affects the RNA products of more than 90% of human genes. Not surprisingly, alternative splicing is observed among gene products of metazoan immune systems, which have evolved to efficiently recognize pathogens and discriminate between "self" and "non-self", and thus need to be both diverse and flexible. In this review we focus on the specific interface between alternative splicing and autoimmune diseases, which result from a malfunctioning of the immune system and are characterized by the inappropriate reaction to self-antigens. Despite the widespread recognition of alternative splicing as one of the major regulators of gene expression, the connections between alternative splicing and autoimmunity have not been apparent. We summarize recent findings connecting splicing and autoimmune disease, and attempt to find common patterns of splicing regulation that may advance our understanding of autoimmune diseases and open new avenues for therapy.

Prostaglandins in pathogenesis and treatment of multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS) characterized by inflammation, demyelination, axonal loss, and gliosis. The inflammatory lesions are manifested by a large infiltration and a heterogeneous population of cellular and soluble mediators of the immune system, such as T cells, B cells, macrophages, and microglia, as well as a broad range of cytokines, chemokines, antibodies, complement, and other toxic substances. Prostaglandins (PGs) are arachidonic acid-derived autacoids that have a role in the modulation of many physiological systems including the CNS, respiratory, cardiovascular, gastrointestinal, genitourinary, endocrine, and immune systems. PG production is associated with inflammation, a major feature in MS that is characterized by the loss of myelinating oligodendrocytes in the CNS. With respect to the role of PGs in the induction of inflammation, they can be effective mediators in the pathophysiology of MS. Thus use of agonists or antagonists of PG receptors may be considered as a new therapeutic protocol in MS. In this review, we try to clarify the role of PGs in immunopathology and treatment of MS.