Soluble Form Of CTLA-4 Research Articles

Soluble form of CTLA-4 is a good predictor for tumor recurrence after radiofrequency ablation in hepatocellular carcinoma patients.

BackgroundA soluble form of cytotoxic‐T‐lymphocyte‐antigen‐4 (sCTLA‐4) is a prognostic biomarker for several cancers but remains unclear in HCC patients. The aim of study is to evaluate the predictive role of serum sCTLA‐4 levels for tumor recurrence of chronic hepatis C (CHC)‐HCC patients receiving radiofrequency ablation (RFA).Material and methodA prospective study recruiting 88 CHC‐HCC patients was done between 2013 and 2019. Cox regression analysis was used to determine the predictors of early recurrence. All tests were two‐tailed, and the level of statistical significance was set as p < 0.05.ResultsDuring a median follow‐up of 44.4 months, 53 of the 88 (60.2%) CHC‐HCC patients encountered early recurrence within 2 years. The predictability of sCTLA‐4 for local recurrence (LR) and intrahepatic metastasis (IHM) by 2‐years using AUROC curve analysis were 0.740 and 0.715, respectively. Patients with high sCTLA‐4 levels (>9 ng/ml) encountered shorter recurrence‐free survival (RFS) for LR (log‐rank p = 0.017) but paradoxically longer RFS for IHM (log‐rank p = 0.007) compared to those with low levels (≤9 ng/ml). By multivariate Cox regression analysis, sCTLA‐4 levels and antiviral therapy were independent prognostic factor of early recurrence both in LR and IHM. A combination of baseline sCTLA‐4 and AFP level could improve the predictability of early LR and IHM with specificity of 80.0% and 79.7% and positive predictive value of 63.3% and 67.3%, respectively.ConclusionssCTLA‐4 level is a good predictor for early HCC recurrence with higher levels indicating susceptibility to early LR, but protecting from early IHM.

Serum sCTLA-4 level is not associated with type 1 diabetes or the coexistence of autoantibodies in children and adolescent patients from the southern region of Saudi Arabia

BackgroundThe soluble form of CTLA-4 (sCTLA-4) is associated with several autoimmune diseases. The aim of the study is to measure the serum sCTLA-4 levels in type I diabetic (T1DM) patients and to assess the presence of autoantibodies for a possible association.MethodsOne hundred forty-two T1DM patients were enrolled in the study. Fifty of them were serologically positive for co-existing autoantibodies. One hundred and five subjects were enrolled in the study, as non-diabetic controls (1–17 years of age; median age—10 years). The serum samples of all the subjects were analyzed with ELISA to detect the concentration of sCTLA-4 and anti-GAD/IA2 IgG. Standard statistical analysis was conducted as required.ResultsNinety-four (66%) subjects of T1DM patients and five (4.7%) subjects of the non-diabetic group had antibodies positive for anti-GAD/IA2. Serum sCTLA-4 was low in most of the subjects of both the diabetic and control groups (p = 0.18). In the control group, nine individuals (8.6%) were positive for sCTLA-4. Similarly, only seven patients (4.9%) in the T1DM group had high levels of sCTLA-4, of which two were found to be double positive for anti-thyroid peroxidase and anti-thyroglobulin antibodies. In addition, among the T1DM patients, no significant relationships were observed between sCTLA-4 levels and age of onset (p = 0.43), disease duration (p = 0.09), or glycemic control (p = 0.32).ConclusionDespite the previous findings of high sCTLA-4 levels in autoimmune diseases, serum levels of sCTLA-4 are not significantly different between T1DM patients and non-diabetic adolescents. Furthermore, we did not observe any association with autoantibody presence, glycemic control, or disease duration.

RGMB enhances the suppressive activity of the monomeric secreted form of CTLA-4

The immunoregulatory molecule CTLA-4 plays a crucial role in the maintenance of immune homeostasis. CTLA-4-neutralizing antibodies are now approved for the treatment of advanced melanoma, and are in development for treating other cancers as well. However, a thorough understanding of CTLA-4 function at the molecular level is necessary in order to develop strategies to prevent the unintended autoimmunity that is frequently associated with systemic blockade of CTLA-4 activity. Here, we describe an extracellular molecule, repulsive guidance molecule B (RGMB) as a novel binding partner of CTLA-4. RGMB expression was detected at high levels in dendritic cell subsets that have been suggested to have tolerogenic capabilities. RGMB binds an extracellular domain of CTLA-4, and specifically strengthens the binding of the monomeric, soluble form of CTLA-4 (sCTLA-4) to CD80, enhancing CTLA-4’s suppressive effect on co-stimulation. Examination of expression data from tumor tissues revealed a negative correlation between RGMB expression and immune activation status in the majority of non-hematologic tumor tissues. These findings advance our understanding of CTLA-4 activity, as well as identify the RGMB/CTLA-4 binding interface as a potential target for the development of novel immune checkpoint blockade therapies.

How far are we from understanding the genetic basis of Hashimoto’s thyroiditis?

Hashimoto’s thyroiditis (HT) is a common autoimmune disease affecting the thyroid. The prevalence of the disease has been increasing in the last years and in many cases it clusters in families. It is currently believed that susceptibility to HT involves interaction between mutation(s) in generally autoimmune-predisposing genes HLA-DR, PTPN22, CTLA-4, and thyroid autoantigen-specific genes, as well as environmental factors. Several mutations have been associated with HT susceptibility, including mutations predisposing to autoimmune disorders in general. The most often cited include PTPN22 c.1858C>T (p.R620W), and CTLA4 c.49A>G (p.T17A) and CT60 (c.6230A>G) in the 3’UTR region. Polymorphisms in CTLA4 contribute to a higher production of autoantibodies in HT patients. In addition, the protective A allele at position 49 causes an increased amount of soluble form of CTLA4, which is much lower in CT60 G/G-positive disease-susceptible individuals. Contrary to expectations, the PTPN22 c.1858C>T transition has been shown to be a gain-of-function mutation, which inhibits TCR signalling. So far only the thyroid-specific gene associated with HT, thyroglobulin (TG), the exons 10 -12 SNP cluster (p.S734A, p.P778=, p.M1027V) has been found to be more prevalent in HT patients. Homozygosity for the C susceptibility allele of an exon 33 SNP (p.R1999W), together with the presence of 1 or 2 copies of the susceptibility allele of one of the 10-12 exons SNP cluster seems to confer the strongest association with AITD for this gene. However, none of the mentioned genes has an effect which would be large enough to explain the predisposition to HT on its own. It is currently accepted that it is rather interaction of a couple of altered genes rather than one single gene, which triggers the phenotype of disorder. In contrast to many other autoimmune diseases, it was impossible to unanimously associate HT with one HLA-DR type. It has but been found that a specific amino acid signature in exon 2 of the HLA-DRB1 gene is important for HT susceptibility. Additional presence of the exon 33 SNP in the TG gene causes a synergistic effect on disease susceptibility. This co-existence probably causes the preferred presentation of mutated TG to autoreactive T-cells by the altered HLA pocket, which then lead to AITD development. Other mutations could partially explain the impact of environmental factors on HT susceptibility: Carriers of the susceptibility allele at position -1623 of the TG promoter region are prone to produce high amounts of TG when encountering IFNα. In summary however, it is impossible to identify a single etiological polymorphism or even gene, which would be responsible for the etiopathology of Hashimoto’s thyroiditis. It seems that there are at least a couple of genes responsible for this disease and that different mutations could be responsible for the different phenotypes of this disorder like the age of symptom onset, occurrence of postpartum thyroiditis, presence of goitre, or a coexisting thyroid carcinoma.

A soluble form of CTLA-4 is present in serum of pediatric patients with acute lymphoblastic leukaemia

A soluble form of CTLA-4 is present in serum of pediatric patients with acute lymphoblastic leukaemia

Lack of association between sCTLA-4 levels in human plasma and common CTLA-4 polymorphisms

BackgroundCytotoxic T lymphocyte antigen-4 (CTLA-4) is an important downregulatory molecule expressed on both T and B lymphocytes. Numerous population genetics studies have documented significant associations between autoimmune diseases and single nucleotide polymorphisms (SNPs) within and around the CTLA-4 region of chromosome 2 in man. Furthermore, circulating levels of a soluble form of CTLA-4 (sCTLA-4) have been reported in a variety of autoimmune mediated diseases. Despite these findings, the relationship between levels of sCTLA-4 protein, mRNA transcript levels, and SNPs within the CTLA-4 region have not been clearly defined. In order to further clarify this relationship, we have tested four different SNPs within the CTLA-4 region among subjects whom are negative (n = 53) versus positive (n = 28) for sCTLA-4.ResultsOur data do not support a clear association between sCTLA-4 levels and any of the four SNPs tested.ConclusionThe variation in the SNPs tested does not appear to effect sCTLA-4 protein levels, despite reports that they affect sCTLA-4 mRNA.

Adenoviral vector persistence in vivo with a soluble form of CTLA4.

Adenoviral vector persistence in vivo with a soluble form of CTLA4.

Requirement of CD28-CD86 costimulation for allergen-specific T cell proliferation and cytokine expression.

Allergen-specific T lymphocytes biased to the production of type 2 cytokines play an important role in the pathophysiology of atopic disease. It is not known whether optimal activation of these T cells requires costimulation via interaction of B7 (CD86/CD80) with CD28. Peripheral blood mononuclear cells (PBMC), isolated from 10 house dust mite Dermatophagoides pteronyssinus (Der p)-allergic asthma patients and 10 non-allergic control individuals, were stimulated with house dust mite (Der p) and the control antigens Candida albicans (CA) and tetanus toxoid (TT). The role of costimulation in activation for proliferation and cytokine mRNA production of peripheral blood T cells was studied by blocking CD28, CTLA-4, and their ligands CD80 (B7-1) and CD86 (B7-2). The proliferation and the production of type 1 and 2 cytokine mRNA by T cells in response to Der p as well as the control antigens TT and CA was inhibited by simultaneously masking CD80 and CD86 using CTLA4-Ig, a soluble form of CTLA-4. Notably, Der p-specific proliferation of T cells from Der p-allergic asthma patients and non-allergic controls were inhibited equally well. Additional experiments with MoAbs revealed that activation of these T cells was optimally inhibited by blocking the interaction of CD28 with CD86. In vitro responses of allergen- and antigen-specific T cells of allergic patients and non-allergic control persons are equally dependent on costimulation via the CD28-CD86 pathway, suggesting that inhibition of this pathway may prevent complete activation of allergen-specific T cells in allergic individuals in vivo.

Prevention and amelioration of collagen-induced arthritis by blockade of the CD28 co-stimulatory pathway: requirement for both B7-1 and B7-2.

Collagen type II-induced arthritis (CIA) is an experimental model of arthritis that has been successfully used to dissect the pathogenesis of human rheumatoid arthritis and to identify potential therapeutic targets. We have used this model to evaluate the role of T cell co-stimulation in both disease development and progression. T cell co-stimulation is provided by ligation of CD28 with either B7-1 or B7-2 present on antigen-presenting cells and can be prevented by a soluble form of CTLA-4 (CTLA-4Ig) which binds with high affinity to both B7-1 and B7-2. We found that administration of CTLA-4Ig at the time of immunization prevented the development of CIA and was associated with lack of lymphocyte expansion within the draining lymph node and failure to produce anti-collagen IgG1 or IgG2a antibodies. To determine which CD28 ligand plays a more dominant role in CIA, we treated mice with monoclonal antibodies (mAb) against either B7-1 or B7-2. Neither anti-B7-1 nor anti-B7-2 had any effect on the course of CIA when given alone, but resulted in reduced incidence and clinical scores when given together. Interestingly, when treatment was delayed until after the onset of clinical disease, both CTLA-4Ig or anti-B7-1 plus anti-B7-2 mAb still ameliorated disease. Effective treatment was associated with a reduction in interferon-gamma production by lymph node cells following stimulation in vitro, suggesting that Th1 responses were diminished. This study points to a critical role of CD28 co-stimulation in the development and perpetuation of CIA in DBA/1 mice. Interestingly, it demonstrates an active role for T cells in the later stages of this disease and implicates both B7-1 and B7-2-mediated co-stimulation in the pathogenesis of CIA.

Collagen-induced arthritis in the BB rat. Prevention of disease by treatment with CTLA-4-Ig.

Antigen-specific T cell activation requires two independent signalling events, one mediated through T cell receptor engagement by the antigen-presenting cell-expressed peptide/class II major histocompatibility complex, and the second through the cognate interactions of costimulatory molecules expressed on the T cell and antigen-presenting cell. There is evidence from in vitro and in vivo experimental systems suggesting that the CD28/B7 costimulatory pathway is crucial for induction of maximal T cell proliferation and T helper-B cell collaboration for IgG production. This pathway can be blocked by CTLA-4-Ig, a soluble form of CTLA-4 which binds with high avidity to the CD28 ligands, B7-1 and B7-2. Here, we show that CTLA-4-Ig treatment prevents clinical and histological manifestations of disease in a collagen-induced arthritis model of rheumatoid arthritis in the diabetes resistant BB/Wor rat, when therapy is initiated before immunization with bovine type II collagen (BIIC). Anti-BIIC antibody titers are reduced in CTLA-4-Ig-treated rats compared to diseased control animals. Histologically, joints from CTLA-4-Ig-treated animals show no histological abnormalities, in contrast to control antibody-treated animals, which show complete erosion of the articular cartilage and bone. Despite the efficacy of CTLA-4-Ig in preventing clinical and histological signs of arthritis and reducing antibody responses to BIIC, delayed type hypersensitivity responses to collagen 18 d or more after CTLA-4-Ig treatment ends are similar in CTLA-4-Ig-treated and untreated rats, suggesting that the prolonged disease suppression observed does not result from induction of T cell anergy.

CTLA4Ig treatment ameliorates the lethality of murine graft-versus-host disease across major histocompatibility complex barriers.

Graft-versus-host disease (GVHD), a pathological condition associated with BMT, results from activation of donor T lymphocytes by host tissues. CD28 and CTLA-4 are structurally related T cell receptors for members of the B7 (CD80) gene family, which transmit important costimulatory signals for T cell activation in vitro and in vivo. Here we have investigated the effects of CTLA4Ig, a soluble form of CTLA-4, on lethal GVHD in a murine model. Lethal GVHD was induced by transfer of parent C57BL/6 bone marrow and spleen cells into lethally irradiated (C57BL/6 x DBA/2)F1 recipients. Short courses of treatment with CTLA4Ig did not block engraftment, but prolonged survival of BMT recipients even when administration was delayed for 6 days after transplantation. CTLA4Ig-treated survivors of GVHD maintained body weight and did not exhibit visible signs of GVHD. However, treatment regimens that maximally prolonged survival did not detectably prevent T cell-mediated hematological abnormalities associated with GVHD, including pancytopenia and abnormal cellular composition of the spleen. Our data thus show that the lethality of acute GVHD in this model system is more dependent upon CD28/CTLA-4 costimulation than are other GVHD-associated abnormalities, and can be blocked for an extended period by brief treatment with CTLA4Ig.

Costimulation of T-cell activation and virus production by B7 antigen on activated CD4+ T cells from human immunodeficiency virus type 1-infected donors.

Infection with the human immunodeficiency virus type 1 (HIV-1) requires T-cell activation. Recent studies have shown that interactions of the T-lymphocyte receptors CD28 and CTLA-4 with their counter receptor, B7, on antigen-presenting cells are required for optimal T-cell activation. Here we show that HIV-1 infection is associated with decreased expression of CD28 and increased expression of B7 on CD4+ T-cell lines generated from seropositive donors by alloantigen stimulation. Loss of CD28 expression was not seen on CD4+ T-cell lines from seronegative donors, but up-regulation of B7 expression was observed upon more prolonged culture. Both T-cell proliferation and interleukin 2 mRNA accumulation in HIV-1-infected cultures required costimulation with exogenous B7 because these events were blocked by CTLA4Ig, a soluble form of CTLA-4 that binds B7 with high avidity. In contrast, levels of HIV-1 RNA were not affected by CTLA4Ig, indicating that regulation of virus transcription in these cultures did not depend upon CD28-B7 engagement. Infected T cells could present alloantigen to fresh, uninfected CD4+ T cells, leading to increased proliferation and virus spread to the activated cells. Both of these events were blocked by CTLA4Ig. Thus, chronic activation of HIV-1-infected CD4+ T cells reduces expression of CD28 and increases expression of B7, thereby enabling these T cells to become antigen-presenting cells for uninfected CD4+ T cells; this might be another mechanism for HIV-1 transmission via T-cell-T-cell contact.