Aberrant production of soluble co-stimulatory molecules CTLA-4 and CD28 in patients with chronic hepatitis B

sCD163, sCD28, sCD80, and sCTLA-4 as soluble marker candidates for detecting immunosenescence

BACKGROUND

Inflammaging, the characteristics of immunosenescence, characterized by continuous chronic inflammation that could not be resolved. It is not only affect older people but can also occur in young individuals, especially those suffering from chronic inflammatory conditions such as autoimmune disease, malignancy, or chronic infection. This condition led to altered immune function and as consequent immune function is reduced. Detection of immunosenescence has been done by examining the immune risk profile (IRP), which uses flow cytometry. These tests are not always available in health facilities, especially in developing countries and require fresh whole blood samples. Therefore, it is necessary to find biomarkers that can be tested using stored serum to make it easier to refer to the examination. Here we proposed an insight for soluble biomarkers which represented immune cells activities and exhaustion, namely sCD163, sCD28, sCD80, and sCTLA-4. Those markers were reported to be elevated in chronic diseases that caused early aging and easily detected from serum samples using ELISA method, unlike IRP. Therefore, we conclude these soluble markers are beneficial to predict pathological condition of immunosenescence.

AIM

To identify soluble biomarkers that could replace IRP for detecting immunosenescence.

CONCLUSION

Soluble costimulatory molecule suchsCD163, sCD28, sCD80, and sCTLA-4 are potential biomarkers for detecting immunosenescence.

Soluble Forms of Immune Checkpoints and Their Ligands as Potential Biomarkers in the Diagnosis of Recurrent Pregnancy Loss-A Preliminary Study

Immune checkpoints (ICPs) serve as regulatory switches on immune-competent cells. Soluble ICPs consist of fragments derived from ICP molecules typically located on cell membranes. Research has demonstrated that they perform similar functions to their membrane-bound counterparts but are directly present in the bloodstream. Effective control of the maternal immune system is vital for a successful pregnancy due to genetic differences between the mother and fetus. Abnormalities in the immune response are widely acknowledged as the primary cause of spontaneous abortions. In our research, we introduce a novel approach to understanding the immune-mediated mechanisms underlying recurrent miscarriages and explore new possibilities for diagnosing and preventing pregnancy loss. The female participants in the study were divided into three groups: RSA (recurrent spontaneous abortion), pregnant, and non-pregnant women. The analysis of soluble forms of immune checkpoints and their ligands in the serum of the study groups was conducted using the Luminex method Statistically significant differences in the concentrations of (ICPs) were observed between physiological pregnancies and the RSA group. Among patients with RSA, we noted reduced concentrations of sGalectin-9, sTIM-3, and sCD155, along with elevated concentrations of LAG-3, sCD80, and sCD86 ICPs, in comparison to physiological pregnancies. Our study indicates that sGalectin-9, TIM-3, sLAG-3, sCD80, sCD86, sVISTA, sNectin-2, and sCD155 could potentially serve as biological markers of a healthy, physiological pregnancy. These findings suggest that changes in the concentrations of soluble immune checkpoints may have the potential to act as markers for early pregnancy loss.

Immune checkpoints on T and NK cells in the context of HBV infection: Landscape, pathophysiology and therapeutic exploitation

In hepatitis B virus (HBV) infection, the interplay between the virus and the host immune system is crucial in determining the pathogenesis of the disease. Patients who fail to mount a sufficient and sustained anti-viral immune response develop chronic hepatitis B (CHB). T cells and natural killer (NK) cells play decisive role in viral clearance, but they are defective in chronic HBV infection. The activation of immune cells is tightly controlled by a combination of activating and inhibitory receptors, called immune checkpoints (ICs), allowing the maintenance of immune homeostasis. Chronic exposure to viral antigens and the subsequent dysregulation of ICs actively contribute to the exhaustion of effector cells and viral persistence. The present review aims to summarize the function of various ICs and their expression in T lymphocytes and NK cells in the course of HBV infection as well as the use of immunotherapeutic strategies targeting ICs in chronic HBV infection.

Soluble TIM3 and Its Ligands Galectin-9 and CEACAM1 Are in Disequilibrium During Alcohol-Related Liver Disease and Promote Impairment of Anti-bacterial Immunity

Background and Aims

Immunoregulatory checkpoint receptors (CR) contribute to the profound immunoparesis observed in alcohol-related liver disease (ALD) and in vitro neutralization of inhibitory-CRs TIM3/PD1 on anti-bacterial T-cells can rescue innate and adaptive anti-bacterial immunity. Recently described soluble-CR forms can modulate immunity in inflammatory conditions, but the contributions of soluble-TIM3 and soluble-PD1 and other soluble-CRs to immune derangements in ALD remain unclear.

Methods

In Alcoholic Hepatitis (AH; n = 19), alcohol-related cirrhosis (ARC; n = 53) and healthy control (HC; n = 27) subjects, we measured by Luminex technology (i) plasma levels of 16 soluble-CRs, 12 pro/anti-inflammatory cytokines and markers of gut bacterial translocation; (ii) pre-hepatic, post-hepatic and non-hepatic soluble-CR plasma levels in ARC patients undergoing TIPS; (iii) soluble-CRs production from ethanol-treated immunocompetent precision cut human liver slices (PCLS); (iv) whole-blood soluble-CR expression upon bacterial challenge. By FACS, we assessed the relationship between soluble-TIM3 and membrane-TIM3 and rescue of immunity in bacterial-challenged PBMCs.

Results

Soluble-TIM3 was the dominant plasma soluble-CR in ALD vs. HC (p = 0.00002) and multivariate analysis identified it as the main driver of differences between groups. Soluble-CRs were strongly correlated with pro-inflammatory cytokines, gut bacterial translocation markers and clinical indices of disease severity. Ethanol exposure or bacterial challenge did not induce soluble-TIM3 production from PCLS nor from whole-blood. Bacterial challenge prompted membrane-TIM3 hyperexpression on PBMCs from ALD patient's vs. HC (p < 0.002) and was inversely correlated with plasma soluble-TIM3 levels in matched patients. TIM3 ligands soluble-Galectin-9 and soluble-CEACAM1 were elevated in ALD plasma (AH > ARC; p < 0.002). In vitro neutralization of Galectin-9 and soluble-CEACAM1 improved the defective anti-bacterial and anti-inflammatory cytokine production from E. coli-challenged PBMCs in ALD patients.

Conclusions

Alcohol-related liver disease patients exhibit supra-physiological plasma levels of soluble-TIM3, particularly those with greater disease severity. This is also associated with increased levels of soluble TIM3-ligands and membrane-TIM3 expression on immune cells. Soluble-TIM3 can block the TIM3-ligand synapse and improve anti-bacterial immunity; however, the increased levels of soluble TIM3-binding ligands in patients with ALD negate any potential immunostimulatory effects. We believe that anti-TIM3 neutralizing antibodies currently in Phase I clinical trials or soluble-TIM3 should be investigated further for their ability to enhance anti-bacterial immunity. These agents could potentially represent an innovative immune-based supportive approach to rescue anti-bacterial defenses in ALD patients.

Circulating CTLA-4 levels and CTLA4 polymorphisms associate with disease condition and progression and hepatocellular carcinoma patients' survival in chronic hepatitis B virus infection

BACKGROUND

CTLA-4 is involved in the immune dysfunction of hepatitis B virus (HBV) infection and hepatocellular carcinoma (HCC). This study analyzed the association of circulating CTLA-4 levels and CTLA4 polymorphisms with disease condition and progression in chronic HBV infection.

METHODS

Serum CTLA-4 levels and CTLA4 rs231775 and rs5742909 polymorphisms were determined in patients with various HBV-related diseases [53 asymptomatic HBV carrier status (ASC), 147 chronic hepatitis, 130 cirrhosis and 102 HCC] and nearly a 10-year follow-up.

RESULTS

Serum CTLA-4 levels were stepwisely increased from ASC, chronic hepatitis, cirrhosis to HCC and independently associated with HCC (OR 2.628, P < 0.001). HCC patients had lower frequencies of rs231775 genotype GA, genotype AA and allele A than ASC, chronic hepatitis and cirrhosis patients. Rs231775 genotype GG was independently associated with HCC (OR 2.324, P = 0.010) and higher CTLA-4 levels in patients with HBV infection. In the follow-up, higher baseline CTLA-4 levels and CTLA4 rs231775 genotype GG significantly associated with disease progression from chronic hepatitis to cirrhosis (OR 2.561, P = 0.011 and OR 2.799, P = 0.015, respectively) or from cirrhosis to HCC (OR 2.673, P = 0.008 and OR 2.097, P = 0.023, respectively) and with a shorter overall survival in HCC patients (HR 0.317, P = 0.018 and HR 0.682, P = 0.026, respectively). Rs5742909 had no significant association with CTLA-4 levels and disease progression.

CONCLUSION

CTLA-4 levels and CTLA4 rs231775 polymorphism associate with the disease condition and progression and HCC development in chronic HBV infection and their determination may be used for monitoring disease progression and predicting patient prognosis.

Soluble CTLA-4 as a favorable predictive biomarker in metastatic melanoma patients treated with ipilimumab: an Italian melanoma intergroup study

CTLA-4 blockade by means of ipilimumab (IPI) potentiates the immune response and improves overall survival (OS) in a minority of metastatic melanoma (MM) patients. We investigated the role of soluble CTLA-4 (sCTLA-4) as a possible biomarker for identifying this subset of patients. sCTLA-4 levels were analyzed at baseline in sera from 113 IPI-treated MM patients by ELISA, and the median value (200 pg/ml) was used to create two equally sized subgroups. Associations of sCTLA-4 with best overall response (BOR) to IPI and immune-related adverse events (irAEs) were evaluated through logistic regression. Kaplan-Meier and Cox regression methods were used to analyze OS. A remarkable association between sCTLA-4 levels and BOR was found. Specifically, the proportion of patients with sCTLA-4 > 200 pg/ml in irSD or irPD (immune-related stable or progressive disease) was, respectively, 80% (OR = 0.23; 95%CL = 0.03-1.88) and 89% (OR = 0.11; 95%CL = 0.02-0.71) and was lower than that observed among patients in irCR/irPR (immune-related complete/partial response). sCTLA-4 levels increased during IPI treatment, since the proportion of patients showing sCTLA > 200 pg/ml after 3 cycles was 4 times higher (OR = 4.41, 95%CL = 1.02-19.1) than that after 1 cycle. Moreover, a significantly lower death rate was estimated for patients with sCTLA-4 > 200 pg/ml (HR = 0.61, 95%CL = 0.39-0.98). Higher baseline sCTLA-4 levels were also associated with the onset of any irAE (p value = 0.029), in particular irAEs of the digestive tract (p value = 0.041). In conclusion, our results suggest that high sCTLA-4 serum levels might predict favorable clinical outcome and higher risk of irAEs in IPI-treated MM patients.

Soluble immune checkpoints in cancer: production, function and biological significance

Immune checkpoints play important roles in immune regulation, and blocking immune checkpoints on the cell membrane is a promising strategy in the treatment of cancer. Based on this, monoclonal antibodies are having much rapid development, such as those against CTLA-4 (cytotoxic T lymphocyte antigen 4) and PD-1 (programmed cell death protein 1).But the cost of preparation of monoclonal antibodies is too high and the therapeutic effect is still under restrictions. Recently, a series of soluble immune checkpoints have been found such as sCTLA-4 (soluble CTLA-4) and sPD-1 (soluble PD-1). They are functional parts of membrane immune checkpoints produced in different ways and can be secreted by immune cells. Moreover, these soluble checkpoints can diffuse in the serum. Much evidence has demonstrated that these soluble checkpoints are involved in positive or negative immune regulation and that changes in their plasma levels affect the development, prognosis and treatment of cancer. Since they are endogenous molecules, they will not induce immunological rejection in human beings, which might make up for the deficiencies of monoclonal antibodies and enhance the utility value of these molecules. Therefore, there is an increasing need for investigating novel soluble checkpoints and their functions, and it is promising to develop relevant therapies in the future. In this review, we describe the production mechanisms and functions of various soluble immune checkpoint receptors and ligands and discuss their biological significance in regard to biomarkers, potential candidate drugs, therapeutic targets, and other topics.

Increased levels of soluble co-stimulatory molecule PD-L1 (B7-H1) in the plasma of viraemic HIV-1+ individuals

Recent evidence has revealed that PD-L1 is expressed in two functional forms, namely, a membrane-bound form (mPD-L1) and a soluble form (sPD-L1). The identification of the soluble form of PD-L1 represents the discovery of a new potential mechanism for the activation of the PD-1 pathway that may mediate a physiological apoptotic mechanism through a cell-cell signalling-independent pathway and may also favour T cell dysfunction during HIV infection. Since the presence of sPD-L1 has not been well established in the scenario of chronic viral infection, we investigated the presence of sPD-L1 in the plasma of viraemic HIV⁺ individuals and the potential mechanism that promotes its production. We report the following: 1) the level of the soluble form of PD-L1 is increased in the plasma of viraemic HIV⁺ individuals, 2) the level of the soluble form of PD-L1 in viraemic HIV⁺ individuals correlates with markers of microbial product translocation and inflammation, 3) the expression of the membrane-bound form of PD-L1 on conventional dendritic cells from viraemic HIV⁺ individuals correlates with the levels of soluble PD-L1 and MMP-2, and 4) monocyte-derived dendritic cells not only increase their expression of mPD-L1 and MMP-2 but also produce sPD-L1 after LPS and TNF-α stimulation, as demonstrated by functional in vitro experiments, which provides insight into the potential source of sPD-L1 production.

A meta-analysis of the association between CTLA-4 genetic polymorphism and susceptibility of asthma

BACKGROUND

Numerous studies have reported an association between cytotoxic T-lymphocyte associated antigen 4 gene (CTLA4) polymorphism and susceptibility to asthma, in different populations, but the results have been inconsistent. We performed a meta-analysis of 19 published case-control studies to obtain a reasonably accurate estimation of the relationship between CTLA4 polymorphism and asthma.

METHODS

We searched the Pubmed, EMBASE, Chinese National Knowledge Infrastructure, and Wanfang databases and extracted data from 19 independent, eligible studies. Odds ratios (ORs) with 95% confidence intervals (CIs) and Egger test were separately used to assess the strength of associations and publication bias.

RESULTS

A total of 19 case-control studies involving 4831 cases and 4534 controls were identified. The combined results revealed that there was significant association between the +49A/G polymorphism and asthma (for GG + GA vs. AA: OR = 0.82, 95% CI = 0.70-0.97, P = .02). Stratification by race or age indicated a significant association between the CTLA-4 +49 GA+GG genotype and asthma in Asians (OR = 0.80, 95% CI = 0.68-0.95, P = .01) and children (OR = 0.75, 95% CI = 0.62-0.90, P = .002), but there was no association in whites (OR = 0.94, 95% CI = 0.80-1.10, P = .44) and adults (OR = 0.85, 95% CI = 0.68-1.06, P = .15). Additionally, there was a significant association with atopic asthma under the random-effects model (OR = 0.81, 95% CI = 0.67-0.98, P = .03). In addition, there was no significant association between the -318 C/T polymorphism and asthma risk.

CONCLUSIONS

Our meta-analysis results suggested that the +49A/G polymorphism in CTLA-4 was an important risk factor for asthma susceptibility, especially in Asian individuals, children, and atopic patients.

Aberrant production of soluble inducible T cell co‑stimulator and soluble programmed cell death protein 1 in patients with chronic hepatitis B

Previous studies demonstrated that immune dysregulation is an important cause of hepatitis B virus (HBV)‑mediated liver damage. Co‑stimulators including programmed cell death protein 1 (PD‑1) and inducible T cell co‑stimulator (ICOS) are involved in the pathogenesis of HBV. In the present study, the serum levels of soluble (s)PD‑1 and sICOS in patients with chronic HBV infections, were investigated, and the association between sPD‑1 and sICOS levels and liver injury degree was investigated. Serum sPD‑1 and sICOS levels were increased in the HBV‑patient group particularly in the HBV external core antigen positive group. In the immune clearance group, sPD‑1 and sICOS were increased compared with the tolerance group. Furthermore, the relative mRNA expression levels were also increased in patients with HBV. However there was no correlation between sPD‑1 and sICOS levels and HBV antibodies or PD‑1/ICOS mRNA copies. The altered sPD‑1 and sICOS serum levels in the different HBV groups may reflect the dysregulation of T cell activation, and may be associated with the HBV pathological process.

CTLA-4 in mesothelioma patients: tissue expression, body fluid levels and possible relevance as a prognostic factor

CTLA-4 function as a negative regulator of T cell-mediated immune response is well established, whereas much less is known about the immunoregulatory role of its soluble isoform (sCTLA-4). No data are available on CTLA-4 expression and prognostic impact in malignant pleural mesothelioma (MPM). We investigated, by immunohistochemistry, CTLA-4 expression in tumor tissues and, by ELISA, sCTLA-4 levels in sera and matched pleural effusions from 45 MPM patients. Prognostic effect of CTLA-4 expression on overall survival (OS) was assessed through Cox regression and prognostic significance expressed as death rate ratio (HR). We found that 56.0 % of MPM tissues expressed CTLA-4 with variable intensity and percentage of positive cells estimated by the immunoreactive score. sCTLA-4 levels were significantly higher in sera (S-sCTLA-4) than in pleural effusions (PE-sCTLA-4) (geometric mean ratio = 2.70, P value = 0.020). CTLA-4 expression at the tissue level was higher in the epithelioid histological subtype than in the sarcomatoid, whereas at the serum level, it was higher in the sarcomatoid subtype. A homogeneous favorable prognostic effect was found for CTLA-4 overexpression in tissue, serum and pleural effusion. Interestingly, only the PE-sCTLA-4 was found to be a statistically significant positive prognostic factor (HR = 0.37, 95 % CI = 0.18-0.77, P value = 0.007). Indeed, PE-sCTLA-4 correlated with CTLA-4 expression in tissues, whereas this latter expression showed a weak association with OS. To confirm our findings, further experimental evidences obtained from a larger cohort of MPM patients are required. However, our results would indicate a positive correlation of PE-sCTLA-4 levels and OS in MPM patients.

Changes of costimulatory molecule CD28 on circulating CD8+ T cells correlate with disease pathogenesis of chronic hepatitis B

Costimulatory signals are critical for antiviral immunity. The aim of this study was to evaluate the change of costimulatory molecule CD28 on circulating CD8⁺ T cells in chronic hepatitis B patients (CHB). Seventy CHB patients and fifty-six healthy controls were included, and forty-eight CHB patients were recruited for 52 weeks of longitudinal investigation. The proportions of circulating CD8⁺CD28⁺ and CD8⁺CD28⁻ subpopulations were determined by flow cytometry, and the CD8⁺CD28⁺/CD8⁺CD28⁻ T cells ratio was calculated. Compared with the subpopulation in healthy controls, high proportions of CD8⁺CD28⁻ subpopulation were observed in CHB patients. Similarly, the CD8⁺CD28⁺/CD8⁺CD28⁻ T cells ratio was significantly decreased in CHB patients compared with healthy controls and correlated significantly with hepatitis B virus (HBV) loads. High proportions of CD8⁺CD28⁻ subpopulation and low CD8⁺CD28⁺/CD8⁺CD28⁻ T cells ratio were observed in hepatitis B e antigen- (HBeAg-) positive individuals as compared with that in HBeAg-negative subjects. A significant decrease in CD8⁺CD28⁻ subpopulation, increase in CD8⁺CD28⁺ subpopulation, and CD8⁺CD28⁺/CD8⁺CD28⁻ T cells ratio were seen in those patients who received efficient antiviral therapy. Thus, aberrant CD28 expression on circulating CD8⁺ T cells and the CD8⁺CD28⁺/CD8⁺CD28⁻ T cells ratio reflect the dysregulation of T cell activation and are related to the pathogenesis of chronic HBV infection.

The CD28/B7 pathway: a novel regulator of plasma cell function

The CD28/B7 pathway is pivotal for the activation, optimal function, and regulation of T cell function. While the CD28 receptor and its ligands B7.1/B7.2 are also expressed on plasma cells, little is known of the role of the CD28/B7 pathway in plasma cell function. In this chapter we discuss the recent studies that have examined the role of CD28 expression on plasma cell function. Both stimulatory and inhibitory effects of CD28 on plasma cells have been reported. Based on our findings we propose that under homeostatic conditions the CD28/B7 interaction mediates regulation of plasma cell function whereas during inflammation this pathway can be perturbed to ramp up Ab production from existing plasma cells.

Immunotherapies: the blockade of inhibitory signals

T lymphocytes require signaling by the T cell receptor and by nonclonotypic cosignaling receptors. The costimulatory and inhibitory signals profoundly influence the course of immune responses by amplifying or reducing the transcriptional effects of T cell receptor triggering. The inhibitory receptors such as CTLA-4, PD-1, and BTLA have recently drawn much attention as potential targets for immunotherapies. This review focuses on the progress that has been made with the mentioned receptors in the field of immunotherapies for autoimmune diseases, malignancies, infectious diseases, and transplantation.

Plasma sCD28, sCTLA-4 levels in neuromyelitis optica and multiple sclerosis during relapse

BACKGROUND

Soluble forms of CD28 (sCD28) and CTLA-4 (sCTLA-4) were associated with many autoimmune diseases like Sjögren's syndrome, systemic lupus erythematosus, asthma, and autoimmune myasthenia gravis. However, sCD28 and sCTLA-4 in neuromyelitis optica (NMO) and multiple sclerosis (MS) patients were less studied.

OBJECTIVE

To measure the plasma sCD28, sCTLA-4 in NMO and MS patients, and investigate whether sCD28 and sCTLA-4 possible use as sensitive biomarkers for diseases activity.

METHODS

Plasma concentrations of sCD28, sCTLA-4 were measured by an enzyme-linked immunosorbent assay (ELISA) in NMO (n=22), MS (n=21) patients and controls (n=18).

RESULTS

The concentration of sCD28 levels were higher in the inflammatory demyelinating diseases cohort compared with the controls (NMO, p=0.034; MS, p=0.026) and the levels of sCD28 were slightly higher in NMO compared with MS. The sCTLA-4 levels were lower in the MS subgroup compared with the controls (p=0.032). Both sCD28 and sCTLA-4 did not show any correlation with EDSS score in NMO and MS patients.

CONCLUSIONS

Our study revealed for the first time that the levels of increased plasma sCD28 and decreased plasma sCTLA-4 in NMO and MS patients, but had little correlation with clinical presentations.