B7-H4 expression in normal and diseased human islet β cells

Integrated Bioinformatics Analysis Revealed Immune Checkpoint Genes Relevant to Type 2 Diabetes

Objective

Chronic low-grade inflammation of the pancreatic islets is the characteristic of type 2 diabetes (T2D), and some of the immune checkpoints may play important roles in the pancreatic islet inflammation. Thus, we aim to explore the immune checkpoint genes (ICGs) associated with T2D, thereby revealing the role of ICGs in the pathogenesis of T2D based on bioinformatic analyses.

Methods

Differentially expressed genes (DEGs) and immune checkpoint genes (ICGs) of islets between T2D and control group were screened from datasets of the Gene Expression Omnibus (GEO). A risk model was built based on the coefficients of ICGs calculated by ridge regression. Functional enrichment analysis and immune cell infiltration estimation were conducted. Correlations between ICGs and hub genes, T2D-related disease genes, insulin secretion genes, and beta cell function-related genes were analyzed. Finally, we conducted RT-PCR to verify the expression of these ICGs.

Results

In total, pancreatic islets from 19 cases of T2D and 84 healthy subjects were included. We identified 458 DEGs. Six significantly upregulated ICGs (CD44, CD47, HAVCR2, SIRPA, TNFSF9, and VTCN1) in T2D were screened out. These ICGs were significantly correlated with several hub genes and T2D-related genes; furthermore, they were correlated with insulin secretion and β cell function-related genes. The analysis of immune infiltration showed that the concentrations of eosinophils, T cells CD4 naive, and T cells regulatory (Tregs) were significantly higher, but CD4 memory resting T cells and monocytes were lower in islets of T2D patients. The infiltrated immune cells in T2D pancreatic islet were associated with these six ICGs. Finally, the expression levels of four ICGs were confirmed by RT-PCR, and three ICGs were validated in another independent dataset.

Conclusion

In conclusion, the identified ICGs may play an important role in T2D. Identification of these differential genes may provide new clues for the diagnosis and treatment of T2D.

B7-H4 Polymorphism Influences the Prevalence of Diabetes Mellitus and Pro-Atherogenic Dyslipidemia in Patients with Psoriasis

Background: The co-inhibitory molecule B7-H4 is located in the genomic regions associated with type 1 diabetes (T1D) susceptibility. However, the correlation of B7-H4 with glycometabolism and dyslipidemia has never been studied. Objective: To explore the influence of B7-H4 polymorphism on the prevalence of diabetes mellitus (DM) and dyslipidemia in psoriasis. Methods: In this single-center cross-sectional study, we recruited 265 psoriatic patients receiving methotrexate (MTX) treatment. Thirteen single-nucleotide polymorphisms (SNPs) in B7-H4 were genotyped. Serum levels of total cholesterol (TC), triglycerides (TG), lipoprotein (a) (LP(a)), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein (LDL), apolipoprotein A1 (ApoA1), and apolipoprotein B (ApoB) were measured at baseline and week 12. Results: The GG genotype carriers of rs12025144 in B7-H4 had a higher prevalence of DM (57.14% vs. 17.71% vs. 18.67%, p = 0.0018), and had a poorer response to MTX in diabetic patients (p < 0.05), compared with AA or AG genotype carriers. The AG genotype of rs2066398 was associated with higher levels of pro-atherogenic lipids. MTX significantly downregulated the level of anti-atherogenic lipid ApoA1 in AA genotype carriers of rs2066398. Conclusions: The genotypes rs12025144 and rs2066398 in B7-H4 were correlated with a higher prevalence of DM and dyslipidemia in psoriasis, respectively.

Antibody targeting of B7-H4 enhances the immune response in urothelial carcinoma

Patients with locally advanced and metastatic urothelial carcinoma have a low survival rate (median 15.7 months, 13.1-17.8), with only a 23% response rate to monotherapy treatment with anti-PDL1 checkpoint immunotherapy. To identify new therapeutic targets, we profiled the immune regulatory signatures during murine cancer development using the BBN carcinogen and identified an increase in the expression of the T cell inhibitory protein B7-H4 (VTCN1, B7S1, B7X). B7-H4 expression temporally correlated with decreased lymphocyte infiltration. While the increase in B7-H4 expression within the bladder by CD11b+ monocytes is shared with human cancers, B7-H4 expression has not been previously identified in other murine cancer models. Higher expression of B7-H4 was associated with worse survival in muscle-invasive bladder cancer in humans, and increased B7-H4 expression was identified in luminal and luminal-papillary subtypes of bladder cancer. Evaluation of B7-H4 by single-cell RNA-Seq and immune mass cytometry of human bladder tumors found that B7-H4 is expressed in both the epithelium of urothelial carcinoma and CD68+ macrophages within the tumor. To investigate the function of B7-H4, treatment of human monocyte and T cell co-cultures with a B7-H4 blocking antibody resulted in enhanced IFN-γ secretion by CD4+ and CD8+ T cells. Additionally, anti-B7-H4 antibody treatment of BBN-carcinogen bladder cancers resulted in decreased tumor size, increased CD8+ T cell infiltration within the bladder, and a complimentary decrease in tumor-infiltrating T regulatory cells (Tregs). Furthermore, treatment with a combination of anti-PD-1 and anti-B7-H4 antibodies resulted in a significant reduction in tumor stage, a reduction in tumor size, and an increased level of tumor necrosis. These findings suggest that antibodies targeting B7-H4 may be a viable strategy for bladder cancers unresponsive to PD-1 checkpoint inhibitors.

B7-H4, a promising target for immunotherapy

The coinhibitory molecule B7-H4, an important member of the B7 family, is abnormally expressed in tumors, inflammation and autoimmune diseases. B7-H4 negatively regulates T cell immune response and promotes immune escape by inhibiting the proliferation, cytokine secretion, and cell cycle of T cells. Moreover, B7-H4 plays an extremely important role in tumorigenesis and tumor development including cell proliferation, invasion, metastasis, anti-apoptosis, etc. In addition, B7-H4 has the other biological functions, such as protection against type 1 diabetes (T1D) and islet cell transplantation. Therefore, B7-H4 has been identified as a novel marker or a therapeutic target for the treatment of tumors, inflammation, autoimmune diseases, and organ transplantation. Here, we summarized the expression profiles, physiological and pathological functions, and regulatory mechanisms of B7-H4, the signaling pathways involved, as well as B7-H4-based immunotherapy.

The B7x Immune Checkpoint Pathway: From Discovery to Clinical Trial

B7x (B7 homolog x, also known as B7-H4, B7S1, and VTCN1) was discovered by ourselves and others in 2003 as the seventh member of the B7 family. It is an inhibitory immune checkpoint of great significance to human disease. Tissue-expressed B7x minimizes autoimmune and inflammatory responses. It is overexpressed in a broad spectrum of human cancers, where it suppresses antitumor immunity. Further, B7x and PD-L1 tend to have mutually exclusive expression in cancer cells. Therapeutics targeting B7x are effective in animal models of cancers and autoimmune disorders, and early-phase clinical trials are underway to determine the efficacy and safety of targeting B7x in human diseases. It took 15 years moving from the discovery of B7x to clinical trials. Further studies will be necessary to identify its receptors, reveal its physiological functions in organs, and combine therapies targeting B7x with other treatments.

Probiotics and Prebiotics for the Amelioration of Type 1 Diabetes: Present and Future Perspectives

Type 1-diabetes (T1D) is an autoimmune disease characterized by immune-mediated destruction of pancreatic beta (β)-cells. Genetic and environmental interactions play an important role in immune system malfunction by priming an aggressive adaptive immune response against β-cells. The microbes inhabiting the human intestine closely interact with the enteric mucosal immune system. Gut microbiota colonization and immune system maturation occur in parallel during early years of life; hence, perturbations in the gut microbiota can impair the functions of immune cells and vice-versa. Abnormal gut microbiota perturbations (dysbiosis) are often detected in T1D subjects, particularly those diagnosed as multiple-autoantibody-positive as a result of an aggressive and adverse immunoresponse. The pathogenesis of T1D involves activation of self-reactive T-cells, resulting in the destruction of β-cells by CD8⁺ T-lymphocytes. It is also becoming clear that gut microbes interact closely with T-cells. The amelioration of gut dysbiosis using specific probiotics and prebiotics has been found to be associated with decline in the autoimmune response (with diminished inflammation) and gut integrity (through increased expression of tight-junction proteins in the intestinal epithelium). This review discusses the potential interactions between gut microbiota and immune mechanisms that are involved in the progression of T1D and contemplates the potential effects and prospects of gut microbiota modulators, including probiotic and prebiotic interventions, in the amelioration of T1D pathology, in both human and animal models.

Upregulation of B7-H4 promotes tumor progression of intrahepatic cholangiocarcinoma

Recent reports show that B7-H4 is highly expressed in a variety of tumor cells, functions as a negative regulator of T cells and then promotes tumor progression. However, its expression and role in intrahepatic cholangiocarcinoma (ICC) remain unclear. In present study, B7-H4 expression in ICC and peritumoral tissues was determined at the level of mRNA and protein, and its bioactivity in ICC cells was studied after modification of B7-H4 expression. Then, the mechanism related to tumor progression induced by B7-H4 expression in ICC cells was explored. Finally, clinical significance of B7-H4 expression in ICC patients was further analyzed. The results showed that B7-H4 expression in ICC was much higher than that in peritumoral tissues at the level of both mRNA and protein. The high level of B7-H4 in ICC cells induced epithelial-to-mesenchymal transitions and promoted invasion and metastasis of tumor cells through activation of ERK1/2 signaling. The elevated B7-H4 expression was associated with the downregulated Bax, upregulated Bcl-2 expression, and activation of caspase-3. Clinically, high B7-H4 expression in tumor samples was significantly related to malignant phenotype, such as lymph node metastasis, high tumor stage, and poor differentiation. ICC patients with high expression of B7-H4 had shorter overall survival (OS) and disease-free survival. Moreover, the B7-H4 expression was an independent prognostic factor for predicting OS and tumor recurrence of ICC patients after operation. In conclusion, high expression of B7-H4 promotes tumor progression of ICC and may be a novel therapeutic target for ICC patients.

Potential targeting of B7-H4 for the treatment of cancer

Observations noting the presence of white blood cell infiltrates within tumors date back more than a century, however the cellular and molecular mechanisms regulating tumor immunity continue to be elucidated. The recent successful use of monoclonal antibodies to block immune regulatory pathways to enhance tumor-specific immune responses for the treatment of cancer has encouraged the identification of additional immune regulatory receptor/ligand pathways. Over the past several years, a growing body of data has identified B7-H4 (VTCN1/B7x/B7S1) as a potential therapeutic target for the treatment of cancer. The potential clinical significance of B7-H4 is supported by the high levels of B7-H4 expression found in numerous tumor tissues and correlation of the level of expression on tumor cells with adverse clinical and pathologic features, including tumor aggressiveness. The biological activity of B7-H4 has been associated with decreased inflammatory CD4⁺ T-cell responses and a correlation between B7-H4-expressing tumor-associated macrophages and FoxP3⁺ regulatory T cells (Tregs) within the tumor microenvironment. Since B7-H4 is expressed on tumor cells and tumor-associated macrophages in various cancer types, therapeutic blockade of B7-H4 could favorably alter the tumor microenvironment allowing for antigen-specific clearance tumor cells. The present review highlights the therapeutic potential of targeting B7-H4.

Tumor Regression and Delayed Onset Toxicity Following B7-H4 CAR T Cell Therapy

B7-H4 protein is frequently overexpressed in ovarian cancer. Here, we engineered T cells with novel B7-H4-specific chimeric antigen receptors (CARs) that recognized both human and murine B7-H4 to test the hypothesis that B7-H4 CAR T cell therapy can be applied safely in preclinical models. B7-H4 CAR T cells specifically secreted IFN-γ and lysed B7-H4(+) targets. In vivo, B7-H4 CAR T cells displayed antitumor reactivity against B7-H4(+) human ovarian tumor xenografts. Unexpectedly, B7-H4 CAR T cell treatment reproducibly showed delayed, lethal toxicity 6-8 weeks after therapy. Comprehensive assessment of murine B7-H4 protein distribution uncovered expression in ductal and mucosal epithelial cells in normal tissues. Postmortem analysis revealed the presence of widespread histologic lesions that correlated with B7-H4(+) expression, and were inconsistent with graft versus host disease. Lastly, expression patterns of B7-H4 protein in normal human tissue were comparable to distribution in mice, advancing our understanding of B7-H4. We conclude that B7-H4 CAR therapy mediates control of cancer outgrowth. However, long-term engraftment of B7-H4 CAR T cells mediates lethal, off-tumor toxicity that is likely due to wide expression of B7-H4 in healthy mouse organs. This model system provides a unique opportunity for preclinical evaluation of safety approaches that limit CAR-mediated toxicity after tumor destruction in vivo.

Loss of Peripheral Protection in Pancreatic Islets by Proteolysis-Driven Impairment of VTCN1 (B7-H4) Presentation Is Associated with the Development of Autoimmune Diabetes

Ag-specific activation of T cells is an essential process in the control of effector immune responses. Defects in T cell activation, particularly in the costimulation step, have been associated with many autoimmune conditions, including type 1 diabetes (T1D). Recently, we demonstrated that the phenotype of impaired negative costimulation, due to reduced levels of V-set domain-containing T cell activation inhibitor 1 (VTCN1) protein on APCs, is shared between diabetes-susceptible NOD mice and human T1D patients. In this study, we show that a similar process takes place in the target organ, as both α and β cells within pancreatic islets gradually lose their VTCN1 protein during autoimmune diabetes development despite upregulation of the VTCN1 gene. Diminishment of functional islet cells' VTCN1 is caused by the active proteolysis by metalloproteinase N-arginine dibasic convertase 1 (NRD1) and leads to the significant induction of proliferation and cytokine production by diabetogenic T cells. Inhibition of NRD1 activity, alternatively, stabilizes VTCN1 and dulls the anti-islet T cell responses. Therefore, we suggest a general endogenous mechanism of defective VTCN1 negative costimulation, which affects both lymphoid and peripheral target tissues during T1D progression and results in aggressive anti-islet T cell responses. This mechanism is tied to upregulation of NRD1 expression and likely acts in two synergistic proteolytic modes: cell-intrinsic intracellular and cell-extrinsic systemic. Our results highlight an importance of VTCN1 stabilization on cell surfaces for the restoration of altered balance of immune control during T1D.

A run on the biobank: what have we learned about type 1 diabetes from the nPOD tissue repository?

PURPOSE OF REVIEW

Since the inaugural year of its biobank in 2007, the Network for Pancreatic Organ Donors with Diabetes program has provided 70 370 human samples to 127 investigators worldwide for projects focused on the pathogenesis of type 1 diabetes (T1D). The purpose of this review was to highlight major advances in our understanding of T1D using works that contain original data from experiments utilizing biospecimens provided by the Network for Pancreatic Organ Donors with Diabetes program. A total of 15 studies, published between 1 June 2013 and 31 December 2014, were selected using various search and filter strategies.

RECENT FINDINGS

The type and frequency of B and/or T-cell immune markers in both the endocrine and exocrine compartments vary in T1D. Enterovirus signals have been identified as having new proteins in the extracellular matrix around infiltrated islets. Novel genes within human islet cell types have been shown to play a role in immunity, infiltration, inflammation, disease progression, cell mass and function. Various cytokines and a complement degradation product have also been detected in the blood or surrounding pancreatic ducts/vasculature.

SUMMARY

These findings, from T1D donors across the disease spectrum, emphasize the notion that pathogenic heterogeneity is a hallmark of the disorder.

A Population-Based Cohort Study of All-Cause and Site-Specific Cancer Incidence Among Patients With Type 1 Diabetes Mellitus in Taiwan

BACKGROUND

The relationship between type 1 diabetes mellitus (T1DM) and cancer incidence remains unclear. We sought to assess the all-cause and site-specific cancer incidence in patients with T1DM.

METHODS

A retrospective cohort study design was employed, in which 14 619 patients with T1DM were retrieved from Taiwan's National Health Insurance medical claims between 2000 and 2007. The study subjects were followed to the end of 2008, and cancer incidence was assessed. We calculated age-, sex-, and calendar year-standardized incidence ratios (SIRs) of all-cause cancer incidence and site-specific neoplasm incidence, with reference to the general population.

RESULTS

Seven hundred and sixty patients were identified for all-cause cancer over 86,610 person-years, representing an incidence rate of 87.75 cases per 10,000 person-years. The incidence rate was higher in males than in female patients (109.86 vs 69.75 cases per 10,000 person-years). T1DM was associated with a significantly increased SIR of all-cause cancer (1.13; 95% confidence interval [CI], 1.05-1.22). The sex-specific SIR was significantly elevated in female patients (1.19; 95% CI, 1.07-1.33), but the SIR for male patients was insignificantly elevated (1.09; 95% CI, 0.99-1.20). Pancreatic cancer showed the greatest increase in SIR among both male and female patients with T1DM. Male patients experienced significantly increased SIRs for kidney, rectum, liver, and colon neoplasm, and significantly increased SIRs were noted for ovarian, bladder, and colon cancer in female patients.

CONCLUSIONS

T1DM was associated with a 13% increase in risk of all-cause cancer incidence. Patients with T1DM should be advised to undergo cancer screening for certain types of cancer.

An anti-B7-H4 antibody-drug conjugate for the treatment of breast cancer

B7-H4 has been implicated in cancers of the female reproductive system and investigated for its possible use as a biomarker for cancer, but there are no preclinical studies to demonstrate that B7-H4 is a molecular target for therapeutic intervention of cancer. We provide evidence that the prevalence and expression levels of B7-H4 are high in different subtypes of breast cancer and that only a few normal tissues express B7-H4 on the cell membrane. These profiles of low normal expression and upregulation in cancer provide an opportunity for the use of antibody-drug conjugates (ADCs), cytotoxic drugs chemically linked to antibodies, for the treatment of B7-H4 positive cancers. We have developed an ADC specific to B7-H4 that uses a linker drug consisting of a potent antimitotic, monomethyl auristatin E (MMAE), linked to engineered cysteines (THIOMAB) via a protease labile linker. We will refer to ADCs that use the THIOMAB format as TDCs to help distinguish the format from standard MC-vc-MMAE ADCs that are conjugated to the interchain disulfide bonds. Anti-B7-H4 (h1D11)-MC-vc-PAB-MMAE (h1D11 TDC) produced durable tumor regression in cell line and patient-derived xenograft models of triple-negative breast cancer. It also binds rat B7-H4 with similar affinity to human and allowed us to test for target dependent toxicity in rats. We found that our anti-B7-H4 TDC has toxicity findings similar to untargeted TDC. Our results validate B7-H4 as an ADC target for breast cancer and support the possible use of this TDC in the treatment of B7-H4(+) breast cancer.

B7-H4 as a protective shield for pancreatic islet beta cells

Auto- and alloreactive T cells are major culprits that damage β-cells in type 1 diabetes (T1D) and islet transplantation. Current immunosuppressive drugs can alleviate immune-mediated attacks on islets. T cell co-stimulation blockade has shown great promise in autoimmunity and transplantation as it solely targets activated T cells, and therefore avoids toxicity of current immunosuppressive drugs. An attractive approach is offered by the newly-identified negative T cell co-signaling molecule B7-H4 which is expressed in normal human islets, and its expression co-localizes with insulin. A concomitant decrease in B7-H4/insulin co-localization is observed in human type 1 diabetic islets. B7-H4 may play protective roles in the pancreatic islets, preserving their function and survival. In this review we outline the protective effect of B7-H4 in the contexts of T1D, islet cell transplantation, and potentially type 2 diabetes. Current evidence offers encouraging data regarding the role of B7-H4 in reversal of autoimmune diabetes and donor-specific islet allograft tolerance. Additionally, unique expression of B7-H4 may serve as a potential biomarker for the development of T1D. Future studies should continue to focus on the islet-specific effects of B7-H4 with emphasis on mechanistic pathways in order to promote B7-H4 as a potential therapy and cure for T1D.