IFN-gamma/TNF-alpha synergism as the final effector in autoimmune diabetes: a key role for STAT1/IFN regulatory factor-1 pathway in pancreatic beta cell death

Anthraquinones and Aloe Vera Extracts as Potential Modulators of Inflammaging Mechanisms: A Translational Approach from Autoimmune to Onco-Hematological Diseases

Inflammaging is a chronic, low-grade inflammatory state that contributes to age-related diseases, including cardiovascular disorders, osteoporosis, neurodegeneration, and cancer. This process involves immunosenescence, oxidative stress, and immune aging, all of which contribute to the breakdown of immune tolerance and the onset of autoimmune disorders. Aloe vera (AV) has recently gained attention for its immunomodulatory, anti-inflammatory, and antioxidant properties. This review explores the effects of AV extracts and anthraquinones (e.g., aloe-emodin, emodin, aloin) on key inflammaging-driven mechanisms in autoimmunity. Our analysis highlights AV's ability to regulate hormone balance, autoantibody production, and cytokine/chemokine signaling (such as interleukin-1β, tumor necrosis factor-α, and interferon-γ). It modulates inflammatory pathways, including mitogen-activated protein kinases (MAPKs) and phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT), thereby inhibiting nuclear factor kappa-light-chain-enhancer of activated B-cell (NF-κB) activation. Additionally, AV enhances antioxidant defenses and restores immune balance by reducing Th1/Th17 subsets while promoting Th2-mediated regulation. Notably, AV also modulates inflammasome-mediated mechanisms and counteracts immunosenescence, which is driven by autophagy-related processes. These effects position AV as a potential integrative approach to mitigating inflammaging-driven autoimmunity. Furthermore, as inflammaging is increasingly recognized in onco-hematological diseases, AV-based strategies may offer novel therapeutic avenues. Future studies should focus on clinical validation, optimizing formulations, and expanding applications to broader age-related and immune-mediated disorders.

Reformed islets: a long-term primary cell platform for exploring mouse and human islet biology

Pancreatic islets are 3D micro-organs that maintain β-cell functionality through cell-cell and cell-matrix communication. While primary islets, the gold standard for in vitro models, have a short culture life of approximately 1-2 weeks, we developed a novel protocol that employs reformed islets following dispersion coupled with a fine-tuned culture environment. Reformed islets exhibit physiological characteristics similar to primary islets, enabling high-resolution imaging and repeated functional assessment. Unlike other in vitro platforms, reformed islets retain an immune population, allowing the study of interactions between β cells and resident and infiltrating immune cells. Analyses showed that reformed islets have a similar composition and cytoarchitecture to primary islets, including macrophages and T cells, and can secrete insulin in response to glucose. Reformed islets exhibited partial dedifferentiation compared to native islets but were otherwise transcriptionally similar. The reformed islets offer a useful platform for studying diabetes pathology and can recapitulate both T1DM and T2DM disease milieus, providing an advantage over other models, such as mouse and human β-cell lines, which lack the input of non-β-endocrine cells and immune cell crosstalk.

Diabetes and susceptibility to COVID-19: Risk factors and preventive and therapeutic strategies

Coronavirus disease 2019 (COVID-19) is a highly infectious disease caused by a novel human coronavirus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Diabetes is a well-known risk factor for infectious diseases with high prevalence and increased severity. Here, we elucidated the possible factors for the increased vulnerability of diabetic patients to SARS-CoV-2 infection and the more severe COVID-19 illness. The worsened prognosis of patients with both COVID-19 and diabetes may be attributable to host receptor angiotensin-converting enzyme 2-assisted viral uptake. Moreover, insulin resistance is often associated with impaired mucosal and skin barrier integrity, resulting in mic-robiota dysbiosis, which increases susceptibility to viral infections. It may also be associated with higher levels of pro-inflammatory cytokines resulting from an impaired immune system in diabetics, inducing a cytokine storm and excessive inflammation. This review describes diabetes mellitus and its complications, explains the risk factors, such as disease characteristics and patient lifestyle, which may contribute to the high susceptibility of diabetic patients to COVID-19, and discusses preventive and therapeutic strategies for COVID-19-positive diabetic patients.

Cracking the type 1 diabetes code: Genes, microbes, immunity, and the early life environment

Type 1 diabetes (T1D) results from a complex interplay of genetic predisposition, immunological dysregulation, and environmental triggers, that culminate in the destruction of insulin-secreting pancreatic β cells. This review provides a comprehensive examination of the multiple factors underpinning T1D pathogenesis, to elucidate key mechanisms and potential therapeutic targets. Beginning with an exploration of genetic risk factors, we dissect the roles of human leukocyte antigen (HLA) haplotypes and non-HLA gene variants associated with T1D susceptibility. Mechanistic insights gleaned from the NOD mouse model provide valuable parallels to the human disease, particularly immunological intricacies underlying β cell-directed autoimmunity. Immunological drivers of T1D pathogenesis are examined, highlighting the pivotal contributions of both effector and regulatory T cells and the multiple functions of B cells and autoantibodies in β-cell destruction. Furthermore, the impact of environmental risk factors, notably modulation of host immune development by the intestinal microbiome, is examined. Lastly, the review probes human longitudinal studies, unveiling the dynamic interplay between mucosal immunity, systemic antimicrobial antibody responses, and the trajectories of T1D development. Insights garnered from these interconnected factors pave the way for targeted interventions and the identification of biomarkers to enhance T1D management and prevention strategies.

Identification of unique cell type responses in pancreatic islets to stress

Diabetes involves the death or dysfunction of pancreatic β-cells. Analysis of bulk sequencing from human samples and studies using in vitro and in vivo models suggest that endoplasmic reticulum and inflammatory signaling play an important role in diabetes progression. To better characterize cell type-specific stress response, we perform multiplexed single-cell RNA sequencing to define the transcriptional signature of primary human islet cells exposed to endoplasmic reticulum and inflammatory stress. Through comprehensive pair-wise analysis of stress responses across pancreatic endocrine and exocrine cell types, we define changes in gene expression for each cell type under different diabetes-associated stressors. We find that β-, α-, and ductal cells have the greatest transcriptional response. We utilize stem cell-derived islets to study islet health through the candidate gene CIB1, which was upregulated under stress in primary human islets. Our findings provide insights into cell type-specific responses to diabetes-associated stress and establish a resource to identify targets for diabetes therapeutics.

Cytokine-induced killer cells-mediated chlorin e6-loaded gold nanostars for targeted NIR imaging and immuno-photodynamic combination therapy for lung cancer

Recently, cytokine-induced killer (CIK) cells have a broad application prospect in the comprehensive diagnosis and treatment of tumors owing to their unique characteristics of killing and targeting malignant tumors. Herein, we report a facile strategy for synthesis of monodisperse gold nanostars (GNSs) based on PEGylation and co-loaded with the photosensitizer chlorin e6 (Ce6) to form GNSs-PEG@Ce6 NPs. Then employing CIK cells loading the as-prepared GNSs-PEG@Ce6 NPs to fabricate a CIK cells-based drug delivery system (GNSs-PEG@Ce6-CIK) for lung cancer. Among them, GNSs was functioned as transport media, Ce6 acted as the near-infrared (NIR) fluorescence imaging agent and photodynamic therapy (PDT), and CIK cells served as targeting vectors for immunotherapy, which can increase the efficiency of tumor enrichment and treatment effect. The results of cellular experiments demonstrated that GNSs-PEG@Ce6 NPs had good dispersibility, water solubility and low toxicity under physiological conditions, and the cultured CIK cells had strong anti-tumor properties. Subsequently, GNSs-PEG@Ce6-CIK could effectively inhibit the growth of A549 cells under the exposure of 633 nm laser, which showed stronger killing effect than that of GNSs-PEG@Ce6 NPs or CIK cells. In addition, they showed good tumor targeting and tumor synergistic killing activityin vivo. Therefore, GNSs-PEG@Ce6-CIK was constructed for targeted NIR fluorescence imaging, enhanced PDT and immunotherapy of lung cancer.

A pairwise cytokine code explains the organism-wide response to sepsis

Sepsis is a systemic response to infection with life-threatening consequences. Our understanding of the molecular and cellular impact of sepsis across organs remains rudimentary. Here, we characterize the pathogenesis of sepsis by measuring dynamic changes in gene expression across organs. To pinpoint molecules controlling organ states in sepsis, we compare the effects of sepsis on organ gene expression to those of 6 singles and 15 pairs of recombinant cytokines. Strikingly, we find that the pairwise effects of tumor necrosis factor plus interleukin (IL)-18, interferon-gamma or IL-1β suffice to mirror the impact of sepsis across tissues. Mechanistically, we map the cellular effects of sepsis and cytokines by computing changes in the abundance of 195 cell types across 9 organs, which we validate by whole-mouse spatial profiling. Our work decodes the cytokine cacophony in sepsis into a pairwise cytokine message capturing the gene, cell and tissue responses of the host to the disease.

AR-A014418, a glycogen synthase kinase-3β inhibitor, mitigates lipopolysaccharide-induced inflammation in rat dental pulp stem cells via NLR family pyrin domain containing 3 inflammasome impairment

Background/purpose

Cell pyroptosis and gingival inflammation have been implicated in periodontitis progression. Our previous study revealed that AR-A014418, a pharmacological inhibitor of glycogen synthase kinase-3β (GSK-3β), can enhance the migratory and osteogenic differentiation abilities of rat dental pulp stem cells (rDPSCs). The present study aimed to explore the effect of AR on the inflammation of rDPSCs.

Materials and methods

The primary rDPSCs were isolated and identified by flow cytometry, as well as Oil red O and Alizarin Red S staining. The rDPSCs were cultured and exposed to lipopolysaccharide (LPS) before treating them with different concentrations of AR-A014418. The cell viability was detected using the CCK-8 assay. The generation and secretion of pro-inflammatory cytokines (IL-18, TNF-α, L-1β, and IL-6) were examined by qPCR and ELISA, respectively. To investigate the activation of the NLRP3 inflammasome, the expression levels of pro-caspase 1, cleaved caspase 1, as well as NLRP3 were analyzed by western blotting and immunofluorescence, respectively.

Results

In the rDPSCs, LPS prohibited cell viability and enhanced the generation and secretion of pro-inflammatory cytokines. LPS upregulated NLRP3 and cleaved caspase-1 protein levels and promoted ASC speck formation in the rDPSCs. AR-A014418 administration effectively blocked the LPS-induced inflammation of the rDPSCs in a dose-dependent way. Mechanistically, AR-A014418 significantly restrained the up-regulation of NLRP3 and cleaved caspase-1 in LPS-treated rDPSCs.

Conclusion

Collectively, our findings suggest that AR-A014418 significantly mitigates LPS-induced inflammation of rDPSCs by blocking the activation of the NLRP3 inflammasome.

A Supportive Role of Mesenchymal Stem Cells on Insulin-Producing Langerhans Islets with a Specific Emphasis on The Secretome

Type 1 Diabetes (T1D) is a chronic autoimmune disease characterized by a gradual destruction of insulin-producing β-cells in the endocrine pancreas due to innate and specific immune responses, leading to impaired glucose homeostasis. T1D patients usually require regular insulin injections after meals to maintain normal serum glucose levels. In severe cases, pancreas or Langerhans islet transplantation can assist in reaching a sufficient β-mass to normalize glucose homeostasis. The latter procedure is limited because of low donor availability, high islet loss, and immune rejection. There is still a need to develop new technologies to improve islet survival and implantation and to keep the islets functional. Mesenchymal stem cells (MSCs) are multipotent non-hematopoietic progenitor cells with high plasticity that can support human pancreatic islet function both in vitro and in vivo and islet co-transplantation with MSCs is more effective than islet transplantation alone in attenuating diabetes progression. The beneficial effect of MSCs on islet function is due to a combined effect on angiogenesis, suppression of immune responses, and secretion of growth factors essential for islet survival and function. In this review, various aspects of MSCs related to islet function and diabetes are described.

GABA and Combined GABA with GAD65-Alum Treatment Alters Th1 Cytokine Responses of PBMCs from Children with Recent-Onset Type 1 Diabetes

Type 1 diabetes (T1D) is an autoimmune disease culminating in the destruction of insulin-producing pancreatic cells. There is a need for the development of novel antigen-specific strategies to delay cell destruction, including combinatorial strategies that do not elicit systemic immunosuppression. Gamma-aminobutyric acid (GABA) is expressed by immune cells, β-cells, and gut bacteria and is immunomodulatory. Glutamic-acid decarboxylase 65 (GAD65), which catalyzes GABA from glutamate, is a T1D autoantigen. To test the efficacy of combinatorial GABA treatment with or without GAD65-immunization to dampen autoimmune responses, we enrolled recent-onset children with T1D in a one-year clinical trial (ClinicalTrials.gov NCT02002130) and examined T cell responses. We isolated peripheral blood mononuclear cells and evaluated cytokine responses following polyclonal activation and GAD65 rechallenge. Both GABA alone and GABA/GAD65-alum treatment inhibited Th1 cytokine responses over the 12-month study with both polyclonal and GAD65 restimulation. We also investigated whether patients with HLA-DR3-DQ2 and HLA-DR4-DQ8, the two highest-risk human leukocyte antigen (HLA) haplotypes in T1D, exhibited differences in response to GABA alone and GABA/GAD65-alum. HLA-DR4-DQ8 patients possessed a Th1-skewed response compared to HLA-DR3-DQ2 patients. We show that GABA and GABA/GAD65-alum present an attractive immunomodulatory treatment for children with T1D and that HLA haplotypes should be considered.

Pathogenic role of Th17 cells in autoimmune thyroid disease and their underlying mechanisms

Autoimmune thyroid disease, encompassing Graves' disease and Hashimoto's thyroiditis, has a very complex etiology. Pathogenesis of the disease involves both genetic susceptibility and environmental triggers. Traditionally, imbalance of T helper cell 1 and 2 was thought to result in the immune disorders in Graves' disease and Hashimoto's thyroiditis. However, increasing evidence recently revealed the important role of T helper 17 cell and its relative cellular and secretory components in the pathogenesis and progression of autoimmune thyroid disease. This review is aimed to summarize the published studies on the involvement of T helper 17 cell in autoimmune thyroid disease and discuss the underlying regulatory mechanisms, which could possibly serve as the foundation of discovering new therapeutic targets.

Organism-Wide Analysis of Sepsis Reveals Mechanisms of Systemic Inflammation

Sepsis is a systemic response to infection with life-threatening consequences. Our understanding of the impact of sepsis across organs of the body is rudimentary. Here, using mouse models of sepsis, we generate a dynamic, organism-wide map of the pathogenesis of the disease, revealing the spatiotemporal patterns of the effects of sepsis across tissues. These data revealed two interorgan mechanisms key in sepsis. First, we discover a simplifying principle in the systemic behavior of the cytokine network during sepsis, whereby a hierarchical cytokine circuit arising from the pairwise effects of TNF plus IL-18, IFN-γ, or IL-1β explains half of all the cellular effects of sepsis on 195 cell types across 9 organs. Second, we find that the secreted phospholipase PLA2G5 mediates hemolysis in blood, contributing to organ failure during sepsis. These results provide fundamental insights to help build a unifying mechanistic framework for the pathophysiological effects of sepsis on the body.

Pancreatic Islet Cells Response to IFNγ Relies on Their Spatial Location within an Islet

Type 1 diabetes (T1D) is an auto-immune disease characterized by the progressive destruction of insulin-producing pancreatic beta cells. While beta cells are the target of the immune attack, the other islet endocrine cells, namely the alpha and delta cells, can also be affected by the inflammatory milieu. Here, using a flow cytometry-based strategy, we compared the impact of IFNγ, one of the main cytokines involved in T1D, on the three endocrine cell subsets isolated from C57BL/6 mouse islets. RNA-seq analyses revealed that alpha and delta cells exposed in vitro to IFNγ display a transcriptomic profile very similar to that of beta cells, with an increased expression of inflammation key genes such as MHC class I molecules, the CXCL10 chemokine and the programmed death-ligand 1 (PD-L1), three hallmarks of IFNγ signaling. Interestingly, at low IFNγ concentration, we observed two beta cell populations (responders and non-responders) based on PD-L1 protein expression. Our data indicate that this differential sensitivity relies on the location of the cells within the islet rather than on the existence of two different beta cells subsets. The same findings were corroborated by the in vivo analysis of pancreatic islets from the non-obese diabetic mouse model of T1D, showing more intense PD-L1 staining on endocrine cells close to immune infiltrate. Collectively, our work demonstrates that alpha and delta cells are as sensitive as beta cells to IFNγ, and suggests a gradual diffusion of the cytokine into an islet. These observations provide novel insights into the in situ inflammatory processes occurring in T1D progression.

Lipid Peroxidation Linking Diabetes and Cancer: The Importance of 4-Hydroxynonenal

Significance: It is commonly believed that diabetes mellitus may be associated with cancer. Hence, diabetic patients are at higher risk for hepatocellular carcinoma, pancreatic cancer, colorectal cancer, and breast cancer, but the mechanisms that may link these two severe diseases are not well understood. Recent Advances: A number of factors have been suggested to promote tumorigenesis in diabetic patients, including insulin resistance, hyperglycemia, dyslipidemia, inflammation, and elevated insulin-like growth factor-1 (IGF-1), which may also promote pro-oxidants, and thereby alter redox homeostasis. The consequent oxidative stress associated with lipid peroxidation appears to be a possible pathogenic link between cancer and diabetes. Critical Issues: Having summarized the above aspects of diabetes and cancer pathology, we propose that the major bioactive product of oxidative degradation of polyunsaturated fatty acids (PUFAs), the reactive aldehyde 4-hydroxynonenal (4-HNE), which is also considered a second messenger of free radicals, may be the key pathogenic factor linking diabetes and cancer. Future Directions: Because the bioactivities of 4-HNE are cell-type and concentration-dependent, are often associated with inflammation, and are involved in signaling processes that regulate antioxidant activities, proliferation, differentiation, and apoptosis, we believe that further research in this direction could reveal options for better control of diabetes and cancer. Controlling the production of 4-HNE to avoid its cytotoxicity to normal but not cancer cells while preventing its diabetogenic activities could be an important aspect of modern integrative biomedicine. Antioxid. Redox Signal. 37, 1222-1233.

TNFα and IFNγ cooperate for efficient pro- to anti-inflammatory transition of macrophages during muscle regeneration

IFNγ is traditionally known as a proinflammatory cytokine with diverse roles in antimicrobial and antitumor immunity. Yet, findings regarding its sources and functions during the regeneration process following a sterile injury are conflicting. Here, we show that natural killer (NK) cells are the main source of IFNγ in regenerating muscle. Beyond this cell population, IFNγ production is limited to a small population of T cells. We further show that NK cells do not play a major role in muscle regeneration following an acute injury or in dystrophic mice. Surprisingly, the absence of IFNγ per se also has no effect on muscle regeneration following an acute injury. However, the role of IFNγ is partially unmasked when TNFα is also neutralized, suggesting a compensatory mechanism. Using transgenic mice, we showed that conditional inhibition of IFNGR1 signaling in muscle stem cells or fibro-adipogenic progenitors does not play a major role in muscle regeneration. In contrast to common belief, we found that IFNγ is not present in the early inflammatory phase of the regeneration process but rather peaks when macrophages are acquiring an anti-inflammatory phenotype. Further transcriptomic analysis suggests that IFNγ cooperates with TNFα to regulate the transition of macrophages from pro- to anti-inflammatory states. The absence of the cooperative effect of these cytokines on macrophages, however, does not result in significant regeneration impairment likely due to the presence of other compensatory mechanisms. Our findings support the arising view of IFNγ as a pleiotropic inflammatory regulator rather than an inducer of the inflammatory response.

The interferon regulatory factors, a double-edged sword, in the pathogenesis of type 1 diabetes

Type 1 diabetes (T1D) is an autoimmune disease resulted from the unrestrained inflammatory attack towards the insulin-producing islet β cells. Although the exact etiology underlying T1D remains elusive, viral infections, especially those specific strains of enterovirus, are acknowledged as a critical environmental cue involved in the early phase of disease initiation. Viral infections could either directly impede β cell function, or elicit pathological autoinflammatory reactions for β cell killing. Autoimmune responses are bolstered by a massive body of virus-derived exogenous pathogen-associated molecular patterns (PAMPs) and the presence of β cell-derived damage-associated molecular patterns (DAMPs). In particular, the nucleic acid components and the downstream nucleic acid sensing pathways serve as the major effector mechanism. The endogenous retroviral RNA, mitochondrial DNA (mtDNA) and genomic fragments generated by stressed or dying β cells induce host responses reminiscent of viral infection, a phenomenon termed as viral mimicry during the early stage of T1D development. Given that the interferon regulatory factors (IRFs) are considered as hub transcription factors to modulate immune responses relevant to viral infection, we thus sought to summarize the critical role of IRFs in T1D pathogenesis. We discuss with focus for the impact of IRFs on the sensitivity of β cells to cytokine stimulation, the vulnerability of β cells to viral infection/mimicry, and the intensity of immune response. Together, targeting certain IRF members, alone or together with other therapeutics, could be a promising strategy against T1D.

Exocrine pancreas regeneration modifies original pancreas to alleviate diabetes in mouse models

Diabetes is a major public health issue because of its widely epidemic nature and lack of cure. Here, we show that pancreas-derived mesenchymal stem cells (PMSCs) are capable of regenerating exocrine pancreas when implanted into the kidney capsule of mice with streptozotocin (STZ)-induced diabetes. Mechanistically, we found that the regenerated exocrine pancreas elevated interleukin-6 (IL-6) in PMSC implants, which transiently activated tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) to inhibit IL-17, thereby rescuing damaged exocrine pancreas and islet β cells. In addition, we used knockout mouse models to show that global lack of IL-6, TNF-α, or IFN-γ resulted in increased severity of STZ-induced diabetes and resistance to PMSC implantation therapy, confirming the roles of these factors in safeguarding pancreatic β cells. Furthermore, removal of the kidney capsule PMSC implants at 28 days after implantation did not affect the PMSC-initiated therapeutic effect on diabetic mice. This study reveals a previously unknown role of exocrine pancreas regeneration in safeguarding β cells and demonstrates a "soil-rescues-seed" strategy for type 1 diabetes therapy.

Beta cell and immune cell interactions in autoimmune type 1 diabetes: How they meet and talk to each other

Background

Scope of review

Major conclusions

Interleukin-35 Prevents the Elevation of the M1/M2 Ratio of Macrophages in Experimental Type 1 Diabetes

Macrophages play an important role in the early development of type 1 diabetes (T1D). Based on the phenotype, macrophages can be classified into pro-inflammatory (M1) and anti-inflammatory (M2) macrophages. Despite intensive research in the field of macrophages and T1D, the kinetic response of M1/M2 ratio has not been studied in T1D. Thus, herein, we studied the M1 and M2 macrophages in the early development of T1D using the multiple low dose streptozotocin (MLDSTZ) mouse model. We determined the proportions of M1 and M2 macrophages in thymic glands, pancreatic lymph nodes and spleens on days 3, 7 and 10 after the first injection of STZ. In addition, we investigated the effect of IL-35 in vivo on the M1/M2 ratio and IL-35⁺ plasmacytoid dendritic cells in diabetic mice and in vitro on the sorted macrophages. Our results revealed that the M1/M2 ratio is higher in STZ-treated mice but this was lowered upon the treatment with IL-35. Furthermore, IL-35 treated mice had lower blood glucose levels and a higher proportion of IL-35⁺ cells among pDCs. Macrophages treated with IL-35 in vitro also had a higher proportion of M2 macrophages. Together, our data indicate that, under diabetic conditions, pro-inflammatory macrophages increased, but IL-35 treatment decreased the pro-inflammatory macrophages and increased anti-inflammatory macrophages, further suggesting that IL-35 prevents hyperglycemia by maintaining the anti-inflammatory phenotype of macrophages and other immune cells. Thus, IL-35 should be further investigated for the treatment of T1D and other autoimmune disorders.

Type 1 Diabetes and Associated Cardiovascular Damage: Contribution of Extracellular Vesicles in Tissue Crosstalk

Significance: Type 1 diabetes (T1D) is characterized by the autoimmune destruction of the insulin secreting β-cells, with consequent aberrant blood glucose levels. Hyperglycemia is the common denominator for most of the chronic diabetic vascular complications, which represent the main cause of life reduction in T1D patients. For this disease, three interlaced medical needs remain: understanding the underlying mechanisms involved in pancreatic β-cell loss; identifying biomarkers able to predict T1D progression and its related complications; recognizing novel therapeutic targets. Recent Advances: Extracellular vesicles (EVs), released by most cell types, were discovered to contain a plethora of different molecules (including microRNAs) with regulatory properties, which are emerging as mediators of cell-to-cell communication at the paracrine and endocrine level. Recent knowledge suggests that EVs may act as pathogenic factors, and be developed into disease biomarkers and therapeutic targets in the context of several human diseases. Critical Issues: EVs have been recently shown to sustain a dysregulated cellular crosstalk able to exacerbate the autoimmune response in the pancreatic islets of T1D; moreover, EVs were shown to be able to monitor and/or predict the progression of T1D and the insurgence of vasculopathies. Future Directions: More mechanistic studies are needed to investigate whether the dysregulation of EVs in T1D patients is solely reflecting the progression of diabetes and related complications, or EVs also directly participate in the disease process, thus pointing to a potential use of EVs as therapeutic targets/tools in T1D. Antioxid. Redox Signal. 36, 631-651.

Suppressive role of E3 ubiquitin ligase FBW7 in type I diabetes in non-obese diabetic mice through mediation of ubiquitination of EZH2

The current study tried to uncover the molecular mechanism of E3 ubiquitin ligase F-box and WD repeat domain-containing 7 (FBW7) in a heritable autoimmune disease, type I diabetes (T1D). After streptozotocin-induced T1D model establishment in non-obese diabetic (NOD) mouse, the protein expression of FBW7, enhancer of zeste homolog 2 (EZH2), and Zinc finger and BTB domain containing 16 (ZBTB16) was quantified. Next, splenocytes and pancreatic beta cells were isolated to measure the production of pro-inflammatory cytokines in splenocytes, as well as islet beta-cell apoptosis. Additionally, the stability of EZH2 induced by FBW7 was analyzed by cycloheximide chase assay. The binding affinity of FBW7 and EZH2 and the consequence of ubiquitination were monitored by co-immunoprecipitation assay. Last, a chromatin immunoprecipitation assay was employed to analyze the accumulation of EZH2 and H3K27me3 at the ZBTB16 promoter region. Our study demonstrated downregulated FBW7 and ZBTB16 and upregulated EZH2 in diabetic NOD mice. Overexpression of FBW7 in the NOD mice inhibited pro-inflammatory cytokine release in the splenocytes and the apoptosis of islets beta cells. FBW7 destabilized EZH2 and accelerated ubiquitin-dependent degradation. EZH2 and H3K27me3 downregulated the ZBTB16 expression by accumulating in the ZBTB16 promoter and methylation. FBW7 upregulates the expression of ZBTB16 by targeting histone methyltransferase EZH2 thus reducing the occurrence of T1D.

Alpk1 Sensitizes Pancreatic Beta Cells to Cytokine-Induced Apoptosis via Upregulating TNF-α Signaling Pathway

Pancreatic beta cell failure is the hallmark of type 1 diabetes (T1D). Recent studies have suggested that pathogen recognizing receptors (PRRs) are involved in the survival, proliferation and function of pancreatic beta cells. So far, little is known about the role of alpha-protein kinase 1 (ALPK1), a newly identified cytosolic PRR specific for ADP-β-D-manno-heptose (ADP-heptose), in beta cell survival. In current study we aimed to fill the knowledge gap by investigating the role of Alpk1 in the apoptosis of MIN6 cells, a murine pancreatic beta cell line. We found that the expression of Alpk1 was significantly elevated in MIN6 cells exposed to pro-inflammatory cytokines, but not to streptozotocin, low-dose or high-dose glucose. Activation of Alpk1 by ADP heptose alone was insufficient to induce beta cell apoptosis. However, it significantly exacerbated cytokine-induced apoptosis in MIN6 cells. Mechanistic investigations showed that Alpk1 activation was potent to further induce the expression of tumor necrosis factor (TNF)-α and Fas after cytokine stimulation, possibly due to enhanced activation of the TIFA/TAK1/NF-κB signaling axis. Treatment of GLP-1 receptor agonist decreased the expression of TNF-α and Fas and improved the survival of beta cells exposed to pro-inflammatory cytokines and ADP heptose. In summary, our data suggest that Alpk1 sensitizes beta cells to cytokine-induced apoptosis by potentiating TNF-α signaling pathway, which may provide novel insight into beta cell failure and T1D development.

TNF-α synergises with IFN-γ to induce caspase-8-JAK1/2-STAT1-dependent death of intestinal epithelial cells

Rewiring of host cytokine networks is a key feature of inflammatory bowel diseases (IBD) such as Crohn's disease (CD). Th1-type cytokines-IFN-γ and TNF-α-occupy critical nodes within these networks and both are associated with disruption of gut epithelial barrier function. This may be due to their ability to synergistically trigger the death of intestinal epithelial cells (IECs) via largely unknown mechanisms. In this study, through unbiased kinome RNAi and drug repurposing screens we identified JAK1/2 kinases as the principal and nonredundant drivers of the synergistic killing of human IECs by IFN-γ/TNF-α. Sensitivity to IFN-γ/TNF-α-mediated synergistic IEC death was retained in primary patient-derived intestinal organoids. Dependence on JAK1/2 was confirmed using genetic loss-of-function studies and JAK inhibitors (JAKinibs). Despite the presence of biochemical features consistent with canonical TNFR1-mediated apoptosis and necroptosis, IFN-γ/TNF-α-induced IEC death was independent of RIPK1/3, ZBP1, MLKL or caspase activity. Instead, it involved sustained activation of JAK1/2-STAT1 signalling, which required a nonenzymatic scaffold function of caspase-8 (CASP8). Further modelling in gut mucosal biopsies revealed an intercorrelated induction of the lethal CASP8-JAK1/2-STAT1 module during ex vivo stimulation of T cells. Functional studies in CD-derived organoids using inhibitors of apoptosis, necroptosis and JAKinibs confirmed the causative role of JAK1/2-STAT1 in cytokine-induced death of primary IECs. Collectively, we demonstrate that TNF-α synergises with IFN-γ to kill IECs via the CASP8-JAK1/2-STAT1 module independently of canonical TNFR1 and cell death signalling. This non-canonical cell death pathway may underpin immunopathology driven by IFN-γ/TNF-α in diverse autoinflammatory diseases such as IBD, and its inhibition may contribute to the therapeutic efficacy of anti-TNFs and JAKinibs.

An Update of Anthraquinone Derivatives Emodin, Diacerein, and Catenarin in Diabetes

Diabetes is part of metabolic diseases and is characterized by high blood sugar levels over a prolonged period as result of an insulin-deficient production or an inappropriate response to insulin by our cells. This chronic disease was the direct cause of 1.6 million deaths in 2016 as reported by the World Health Organization. Emodin is a natural product and active ingredient of various Chinese herbs with the chemical formula 1,3,8-trihydroxy-6-methylanthraquinone. Diacerein is another naturally occurring anthraquinone (1,8-diacetoxy-3-carboxyanthraquinone) commonly used as commercial drug to treat osteoarthritis. These two anthraquinone derivatives have been shown to exert antidiabetic activities. Emodin seems to enhance the glucose tolerance and insulin sensibility via activation of PPARγ and modulation of metabolic-related genes. Diacerein seems to decrease inflammatory cytokines and increase insulin secretion enhancing insulin sensibility and therefore improving glucose control. Other naturally occurring anthraquinone derivatives, such as catenarin (1,4,6,8-tetrahydroxy-3-methylanthraquinone), have been shown to have antidiabetic activities although few studies have been performed. The synthesis of new emodin derivatives is increasing, but these new molecules have not been tested for diabetes treatment. In the current work, available literature on anthraquinone derivatives' effects in diabetes disease is reviewed. Moreover, we discuss the chemistry, food sources, bioavailability, and toxicity of the naturally occurring anthraquinone with antidiabetic effects.

The Role of Programmed Death-1 in Type 1 Diabetes

PURPOSE OF REVIEW

Programmed death-1 (PD-1) is an inhibitory receptor that controls T and B cell proliferation and function through interacting with its ligand PD-L1 or PD-L2. PD-1/PD-L1 blockade reboots anti-tumor immunity and is currently used to treat > 15 different types of cancer. However, the response rate is not at 100% and some patients relapse. Importantly, up to 37% of patients treated with PD-1/PD-L1 blocking antibodies develop immune-related adverse events, including overt autoimmunity, such as type 1 diabetes (T1D). Herein, we discuss the role of PD-1, PD-L1, and PD-L2 signaling in pre-clinical models of T1D, including recent work from our laboratory.

RECENT FINDINGS

We highlight ongoing efforts to harness PD-1/PD-L1 signaling and treat autoimmunity. We also evaluate studies aimed at defining biomarkers that could reliably predict the development of immune-related adverse events after clinical PD-1/PD-L1 blockade. With increasing use of PD-1 blockade in the clinic, onset of autoimmunity is a growing health concern. In this review, we discuss what is known about the role of PD-1 pathway signaling in T1D and comment on ongoing efforts to identify patients at risk of T1D development after PD-1 pathway blockade.

The Effects of Type 2 Diabetes Mellitus on Organ Metabolism and the Immune System

Metabolic abnormalities such as dyslipidemia, hyperinsulinemia, or insulin resistance and obesity play key roles in the induction and progression of type 2 diabetes mellitus (T2DM). The field of immunometabolism implies a bidirectional link between the immune system and metabolism, in which inflammation plays an essential role in the promotion of metabolic abnormalities (e.g., obesity and T2DM), and metabolic factors, in turn, regulate immune cell functions. Obesity as the main inducer of a systemic low-level inflammation is a main susceptibility factor for T2DM. Obesity-related immune cell infiltration, inflammation, and increased oxidative stress promote metabolic impairments in the insulin-sensitive tissues and finally, insulin resistance, organ failure, and premature aging occur. Hyperglycemia and the subsequent inflammation are the main causes of micro- and macroangiopathies in the circulatory system. They also promote the gut microbiota dysbiosis, increased intestinal permeability, and fatty liver disease. The impaired immune system together with metabolic imbalance also increases the susceptibility of patients to several pathogenic agents such as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Thus, the need for a proper immunization protocol among such patients is granted. The focus of the current review is to explore metabolic and immunological abnormalities affecting several organs of T2DM patients and explain the mechanisms, whereby diabetic patients become more susceptible to infectious diseases.

Pancreatic islet dysfunction in type 2 diabetes mellitus

Islet dysfunction is a hallmark of type 2 diabetes mellitus (T2DM). Compelling evidence suggests that accumulation of islet amyloid in the islets of Langerhans significantly contribute to β-cell dysfunction and diabetes. Emerging evidence implicates a role for cystic fibrosis transmembrane-conductance regulator in the regulation of insulin secretion from pancreatic islets. Impaired first-phase insulin responses and glucose homeostasis have also been reported in cystic fibrosis patients. The transforming growth factor-β protein superfamily is central regulators of pancreatic cell function, and has a key role in pancreas development and pancreatic disease, including diabetes and islet dysfunction. It is also becoming clear that islet inflammation plays a key role in the development of islet dysfunction. Inflammatory changes, including accumulation of macrophages, have been documented in type 2 diabetic islets. Islet dysfunction leads to hyperglycemia and ultimately the development of diabetes. In this review, we describe these risk factors and their associations with islet dysfunction.

Systematic Transcriptome and Regulatory Network Analyses Reveal the Hypoglycemic Mechanism of Dendrobium fimbriatum

Type 2 diabetes (T2D) is a long-term metabolic disorder disease characterized by high blood sugar and relative lack of insulin. Previous studies have demonstrated that Dendrobium has potent glucose-lowing effects and may serve as add-ons or alternatives to classic medications for T2D prevention and treatment, but the underlying molecular mechanisms were still unclear. We performed biochemical and transcriptional profiling (RNA sequencing [RNA-seq] and microRNA sequencing [miRNA-seq]) analyses on the pancreas and liver of Dendrobium fimbriatum extract (DFE)-fed diabetic rats and control animals. Our sequencing and experimental data indicated that DFE significantly alleviated diabetes symptoms through inhibiting inflammation and preventing islet cell apoptosis in diabetic pancreas. Transcription factors in Stat/nuclear factor κB (NF-κB)/Irf families combined with miR-148a/375/9a served as key regulators in the inflammation and apoptosis pathways under DFE administration. Meanwhile, DFE improved the energy metabolism, lipid transport, and oxidoreductase activity in the liver, and thus decreased lipid accumulation and lipotoxicity-induced hepatocyte apoptosis. Our findings revealed that DFE may serve as a potential therapeutic agent to prevent T2D, and also showed the combination of transcriptome profiling and regulatory network analysis could act as an effective approach for investigating potential molecular mechanisms of traditional Chinese medicine on diseases.

JAK/STAT signaling controls the fate of CD8+CD103+ tissue-resident memory T cell in lupus nephritis

Autoimmune mediated inflammation and renal damage in lupus nephritis (LN) depends partly on the infiltration of lymphocytes in glomeruli and renal interstitium. Here we identified a population of CD8⁺ T cells with a CD103⁺-phenotype in the healthy kidneys of human and mouse. These cells were typically CD69⁺CD103⁺ tissue-resident memory T cells (T_RM) in the kidney. CD8⁺ T_RM cells were expanded in the kidneys of patients with LN or MRL/lpr mice. The expansion of renal CD8⁺ T_RM cells correlated significantly with kidney disease activity. These cells were active in producing cytokines, perforin and granzyme B in the kidney of MRL/lpr mice. Importantly, renal CD8⁺ T_RM cells underwent proliferation and self-renewal to maintain a stable T_RM pool in the kidney of MRL/lpr mice, contributing to renal inflammation and damage. JAK/STAT signaling in the MRL/lpr mice was required for renal T_RM self-renewal as well as maintenance of effector functions. Targeting JAK/STAT signaling by tofacitinib effectively suppressed effector functions and impaired the survival of renal T_RM cells in the kidney, contributing to improved kidney function in MRL/lpr mice. These results provided evidences that renal CD8⁺ T_RM cells play a role in the pathogenesis of LN. They could serve as a therapeutic target for LN.

Comprehensive Proteomics Analysis of Stressed Human Islets Identifies GDF15 as a Target for Type 1 Diabetes Intervention

Type 1 diabetes (T1D) results from the progressive loss of β cells, a process propagated by pro-inflammatory cytokine signaling that disrupts the balance between pro- and anti-apoptotic proteins. To identify proteins involved in this process, we performed comprehensive proteomics of human pancreatic islets treated with interleukin-1β and interferon-γ, leading to the identification of 11,324 proteins, of which 387 were significantly regulated by treatment. We then tested the function of growth/differentiation factor 15 (GDF15), which was repressed by the treatment. We found that GDF15 translation was blocked during inflammation, and it was depleted in islets from individuals with T1D. The addition of exogenous GDF15 inhibited interleukin-1β+interferon-γ-induced apoptosis of human islets. Administration of GDF15 reduced by 53% the incidence of diabetes in NOD mice. Our approach provides a unique resource for the identification of the human islet proteins regulated by cytokines and was effective in discovering a potential target for T1D therapy.

Bempegaldesleukin selectively depletes intratumoral Tregs and potentiates T cell-mediated cancer therapy

High dose interleukin-2 (IL-2) is active against metastatic melanoma and renal cell carcinoma, but treatment-associated toxicity and expansion of suppressive regulatory T cells (Tregs) limit its use in patients with cancer. Bempegaldesleukin (NKTR-214) is an engineered IL-2 cytokine prodrug that provides sustained activation of the IL-2 pathway with a bias to the IL-2 receptor CD122 (IL-2Rβ). Here we assess the therapeutic impact and mechanism of action of NKTR-214 in combination with anti-PD-1 and anti-CTLA-4 checkpoint blockade therapy or peptide-based vaccination in mice. NKTR-214 shows superior anti-tumor activity over native IL-2 and systemically expands anti-tumor CD8+ T cells while inducing Treg depletion in tumor tissue but not in the periphery. Similar trends of intratumoral Treg dynamics are observed in a small cohort of patients treated with NKTR-214. Mechanistically, intratumoral Treg depletion is mediated by CD8+ Teff-associated cytokines IFN-γ and TNF-α. These findings demonstrate that NKTR-214 synergizes with T cell-mediated anti-cancer therapies.

Interferon-gamma drives programmed death-ligand 1 expression on islet β cells to limit T cell function during autoimmune diabetes

Type 1 diabetes is caused by autoreactive T cell-mediated β cell destruction. Even though co-inhibitory receptor programmed death-1 (PD-1) restrains autoimmunity, the expression and regulation of its cognate ligands on β cell remains unknown. Here, we interrogated β cell-intrinsic programmed death ligand-1 (PD-L1) expression in mouse and human islets. We measured a significant increase in the level of PD-L1 surface expression and the frequency of PD-L1+ β cells as non-obese diabetic (NOD) mice aged and developed diabetes. Increased β cell PD-L1 expression was dependent on T cell infiltration, as β cells from Rag1-deficient mice lacked PD-L1. Using Rag1-deficient NOD mouse islets, we determined that IFN-γ promotes β cell PD-L1 expression. We performed analogous experiments using human samples, and found a significant increase in β cell PD-L1 expression in type 1 diabetic samples compared to type 2 diabetic, autoantibody positive, and non-diabetic samples. Among type 1 diabetic samples, β cell PD-L1 expression correlated with insulitis. In vitro experiments with human islets from non-diabetic individuals showed that IFN-γ promoted β cell PD-L1 expression. These results suggest that insulin-producing β cells respond to pancreatic inflammation and IFN-γ production by upregulating PD-L1 expression to limit self-reactive T cells.

Neutralization Versus Reinforcement of Proinflammatory Cytokines to Arrest Autoimmunity in Type 1 Diabetes

As physiological pathways of intercellular communication produced by all cells, cytokines are involved in the pathogenesis of inflammatory insulitis as well as pivotal mediators of immune homeostasis. Proinflammatory cytokines including interleukins, interferons, transforming growth factor-β, tumor necrosis factor-α, and nitric oxide promote destructive insulitis in type 1 diabetes through amplification of the autoimmune reaction, direct toxicity to β-cells, and sensitization of islets to apoptosis. The concept that neutralization of cytokines may be of therapeutic benefit has been tested in few clinical studies, which fell short of inducing sustained remission or achieving disease arrest. Therapeutic failure is explained by the redundant activities of individual cytokines and their combinations, which are rather dispensable in the process of destructive insulitis because other cytolytic pathways efficiently compensate their deficiency. Proinflammatory cytokines are less redundant in regulation of the inflammatory reaction, displaying protective effects through restriction of effector cell activity, reinforcement of suppressor cell function, and participation in islet recovery from injury. Our analysis suggests that the role of cytokines in immune homeostasis overrides their contribution to β-cell death and may be used as potent immunomodulatory agents for therapeutic purposes rather than neutralized.

TNF-α and IFN-γ Together Up-Regulates Par-4 Expression and Induce Apoptosis in Human Neuroblastomas

The objective of this study was to examine the combined effect of Interferon-gamma (IFN-γ) and Tumor Necrosis factor-alpha (TNF-α) on cytotoxicity and expression of prostate apoptosis response-4 (Par-4) and Par-4 interacting proteins B-cell lymphoma (Bcl-2), nuclear factor kappa-light-chain-enhancer of activated B cells/p65 subunit (NF-κB/p65), Ak mouse strain thymoma (Akt) in human neuroblastoma (NB) cells. Materials and methods included human neuroblastoma cell lines-SK-N-MC, SK-N-SH, and SH-SY5Y, which were treated with IFN-γ and TNF-α individually, or in combination, and were assessed for viability by tetrazolium (MTT) assay. Apoptosis was monitored by hypodiploid population (by flow cytometry), DNA fragmentation, Poly (ADP-ribose) polymerase (PARP) cleavage, and caspase-8 activity. Transcript level of Par-4 was measured by RT-PCR. Protein levels of Par-4 and suppressor of cytokine signaling 3 (SOCS-3) were assessed by immunoblotting. Cellular localization of Par-4 and p65 was examined by immunofluorescence. Unbiased transcript analysis for IFN-γ, TNF-α, and Par-4 were analyzed from three independent clinical datasets from neuroblastoma patients. In terms of results, SK-N-MC cells treated with a combination of, but not individually with, IFN-γ and TNF-α induced apoptosis characterized by hypodiploidy, DNA fragmentation, PARP cleavage, and increased caspase-8 activity. Apoptosis was associated with up-regulation of Par-4 mRNA and protein expression. Immunofluorescence studies revealed that Par-4 was localized exclusively in cytoplasm in SK-N-MC cells cultured for 24 h. but showed nuclear localization at 48 h. Treatment with IFN-γ and TNF-α together enhanced the intensity of nuclear Par-4. In gene expression, data from human neuroblastoma patients, levels of IFN-γ, and TNF-α have strong synergy with Par-4 expression and provide good survival advantage. The findings also demonstrated that apoptosis was associated with reduced level of pro-survival proteins–Bcl-2 and Akt and NF-κB/p65. Furthermore, the apoptotic effect induced by IFN-γ-induced Signal Transducer and Activator of Transcription-1(STAT-1), and could be due to down-regulation of suppressor of cytokine signaling-3 (SOCS3). The study concludes that a combinatorial approach using IFN-γ and TNF-α can be explored to maximize the effect in chemotherapy in neuroblastoma, and implies a role for Par-4 in the process.

Abnormal Glucose Metabolism in Rheumatoid Arthritis

The incidence of abnormal glucose metabolism in patients with rheumatoid arthritis was considerably higher than the general population. The persistent systemic inflammatory state in rheumatoid arthritis might be associated with the glucose metabolism dysfunction. In this context, insulin resistance, islet β cell apoptosis, inflammatory cytokines, and other aspects which were linked with abnormal glucose metabolism in rheumatoid arthritis were reviewed. This review will be helpful in understanding the abnormal glucose metabolism mechanism in patients with rheumatoid arthritis and might be conducive to finding an effective treatment.

Dual genetic absence of STAT6 and IL-10 does not abrogate anti-hyperglycemic effects of Schistosoma mansoni in streptozotocin-treated diabetic mice

Schistosoma mansoni (Sm) is known to exert protective effects against various allergic and autoimmune disorders. It has been reported that this parasite protects NOD mice from spontaneous type 1 diabetes (T1D) and ameliorates streptozotocin (STZ)-induced T1D in wild-type mice. Here, we tried to clarify the anti-diabetic mechanisms of Sm in the latter model. Sm infection partially prevented the degradation of pancreatic islets and hyperglycemia in multiple low-dose (MLD) STZ-treated mice. Neither Treg cell depletion nor genetic absences of IL-10 and/or STAT6 abrogated the anti-hyperglycemic effects of Sm. Among M2 macrophage markers, Arg-1 and Ym1, but not Retnla, remained up-regulated in the pancreatic lymph nodes and in the spleens of STAT6/IL-10 double deficient (DKO) mice. Collectively, it is suggested that Sm exerts anti-diabetic effects on this experimental T1D model via Treg/IL-4/IL-13/IL-10-independent mechanisms. Augmented expressions of Arg-1 and Ym1 in the lymphoid organs adjacent to pancreas may be relevant to the anti-diabetic effects of Sm.

Interferon regulatory factor signaling in autoimmune disease

Interferon regulatory factors (IRFs) play critical roles in pathogen-induced innate immune responses and the subsequent induction of adaptive immune response. Dysregulation of IRF signaling is therefore thought to contribute to autoimmune disease pathogenesis. Indeed, numerous murine in vivo studies have documented protection from or enhanced susceptibility to particular autoimmune diseases in Irf-deficient mice. What has been lacking, however, is replication of these in vivo observations in primary immune cells from patients with autoimmune disease. These types of studies are essential as the majority of in vivo data support a protective role for IRFs in Irf-deficient mice, yet IRFs are often found to be overexpressed in patient immune cells. A significant body of work is beginning to emerge from both of these areas of study - mouse and human.

T Cell-Mediated Beta Cell Destruction: Autoimmunity and Alloimmunity in the Context of Type 1 Diabetes

Type 1 diabetes (T1D) results from destruction of pancreatic beta cells by T cells of the immune system. Despite improvements in insulin analogs and continuous blood glucose level monitoring, there is no cure for T1D, and some individuals develop life-threatening complications. Pancreas and islet transplantation have been attractive therapeutic approaches; however, transplants containing insulin-producing cells are vulnerable to both recurrent autoimmunity and conventional allograft rejection. Current immune suppression treatments subdue the immune system, but not without complications. Ideally a successful approach would target only the destructive immune cells and leave the remaining immune system intact to fight foreign pathogens. This review discusses the autoimmune diabetes disease process, diabetic complications that warrant a transplant, and alloimmunity. First, we describe the current understanding of autoimmune destruction of beta cells including the roles of CD4 and CD8 T cells and several possibilities for antigen-specific tolerance induction. Second, we outline diabetic complications necessitating beta cell replacement. Third, we discuss transplant recognition, potential sources for beta cell replacement, and tolerance-promoting therapies under development. We hypothesize that a better understanding of autoreactive T cell targets during disease pathogenesis and alloimmunity following transplant destruction could enhance attempts to re-establish tolerance to beta cells.

Cytokine-induced release of ceramide-enriched exosomes as a mediator of cell death signaling in an oligodendroglioma cell line

Th1 pro-inflammatory cytokines, i.e., TNF-α and IFN-γ, in combination are known to induce cell death in several cell types, including oligodendrocytes, but the mechanism of their synergistic cytotoxicity is unclear. Although ceramide (Cer) has been implicated in cytokine- and stress-induced cell death, its intracellular levels alone cannot explain cytokine synergy. We considered the possibility that Cer released as part of extracellular vesicles may contribute to cytokine-induced synergistic cell death. Using a human oligodendroglioma (HOG) cell line as a model, here we show that exosomes derived from TNF-α-treated "donor" cells, while being mildly toxic to fresh cultures (similar to individual cytokines), induce enhanced cell death when added to IFN-γ-primed target cultures in a fashion resembling the effect of cytokine combination. Further, the sphingolipid profiles of secreted exosomes, as determined by HPLC-MS/MS, revealed that the treatment with the cytokines time-dependently induced the formation and exosomal release, in particular of C16-, C24-, and C24:1-Cer species; C16-, C24-, and C24:1-dihydroCer species; and C16-, C24-, and C24:1-SM species. Finally, exogenous C6-Cer or C16-Cer mimicked and enhanced the cytotoxic effects of the cytokines upon HOG cells, thereby supporting the cell death-signaling role of extracellular Cer.

LIGHT/IFN-γ triggers β cells apoptosis via NF-κB/Bcl2-dependent mitochondrial pathway

LIGHT recruits and activates naive T cells in the islets at the onset of diabetes. IFN‐γ secreted by activated T lymphocytes is involved in beta cell apoptosis. However, whether LIGHT sensitizes IFNγ‐induced beta cells destruction remains unclear. In this study, we used the murine beta cell line MIN6 and primary islet cells as models for investigating the underlying cellular mechanisms involved in LIGHT/IFNγ – induced pancreatic beta cell destruction. LIGHT and IFN‐γ synergistically reduced MIN6 and primary islet cells viability; decreased cell viability was due to apoptosis, as demonstrated by a significant increase in Annexin V⁺ cell percentage, detected by flow cytometry. In addition to marked increases in cytochrome c release and NF‐κB activation, the combination of LIGHT and IFN‐γ caused an obvious decrease in expression of the anti‐apoptotic proteins Bcl‐2 and Bcl‐xL, but an increase in expression of the pro‐apoptotic proteins Bak and Bax in MIN6 cells. Accordingly, LIGHT deficiency led to a decrease in NF‐κB activation and Bak expression, and peri‐insulitis in non‐obese diabetes mice. Inhibition of NF‐κB activation with the specific NF‐κB inhibitor, PDTC (pyrrolidine dithiocarbamate), reversed Bcl‐xL down‐regulation and Bax up‐regulation, and led to a significant increase in LIGHT‐ and IFN‐γ‐treated cell viability. Moreover, cleaved caspase‐9, ‐3, and PARP (poly (ADP‐ribose) polymerase) were observed after LIGHT and IFN‐γ treatment. Pretreatment with caspase inhibitors remarkably attenuated LIGHT‐ and IFNγ‐induced cell apoptosis. Taken together, our results indicate that LIGHT signalling pathway combined with IFN‐γ induces beta cells apoptosis via an NF‐κB/Bcl2‐dependent mitochondrial pathway.

Myt3 suppression sensitizes islet cells to high glucose-induced cell death via Bim induction

Diabetes is a chronic disease that results from the body's inability to properly control circulating blood glucose levels. The loss of glucose homoeostasis can arise from a loss of β-cell mass because of immune-cell-mediated attack, as in type 1 diabetes, and/or from dysfunction of individual β-cells (in conjunction with target organ insulin resistance), as in type 2 diabetes. A better understanding of the transcriptional pathways regulating islet-cell survival is of great importance for the development of therapeutic strategies that target β-cells for diabetes. To this end, we previously identified the transcription factor Myt3 as a pro-survival factor in islets following acute suppression of Myt3 in vitro. To determine the effects of Myt3 suppression on islet-cell survival in vivo, we used an adenovirus to express an shRNA targeting Myt3 in syngeneic optimal and marginal mass islet transplants, and demonstrate that suppression of Myt3 impairs the function of marginal mass grafts. Analysis of grafts 5 weeks post-transplant revealed that grafts transduced with the shMyt3 adenovirus contained ~20% the number of transduced cells as grafts transduced with a control adenovirus. In fact, increased apoptosis and significant cell loss in the shMyt3-transduced grafts was evident after only 5 days, suggesting that Myt3 suppression sensitizes islet cells to stresses present in the early post-transplant period. Specifically, we find that Myt3 suppression sensitizes islet cells to high glucose-induced cell death via upregulation of the pro-apoptotic Bcl2 family member Bim. Taken together these data suggest that Myt3 may be an important link between glucotoxic and immune signalling pathways.

Red wine polyphenol extract efficiently protects intestinal epithelial cells from inflammation via opposite modulation of JAK/STAT and Nrf2 pathways

The development of therapeutic approaches combining efficacy and safety represents an important goal in intestinal inflammation research. Recently, evidence has supported dietary polyphenols as useful tools in the treatment and prevention of chronic inflammatory diseases, but the mechanisms of action are still poorly understood. We here reveal molecular mechanisms underlying the anti-inflammatory action of a non-alcoholic polyphenol red wine extract (RWE), operating at complementary levels via the Janus kinase/signal transducer and activator of transcription (JAK/STAT) and Nuclear factor-erythroid 2-related factor-2 (Nrf2) pathways. RWE significantly reduced the nuclear levels of phosphorylated STAT1 and also the cellular levels of phosphorylated JAK1 induced by cytokines, suppressing the JAK/STAT inflammatory signalling cascade. In turn, RWE increased the Nrf2 nuclear level, activating the Nrf2 pathway, leading not only to an up-regulation of the heme oxygenase-1 (HO-1) expression but also to an increase of the glutamate-cysteine ligase subunit catalytic (GCLc) gene expression, enhancing the GSH synthesis, thereby counteracting GSH depletion that occurs under inflammatory conditions. Overall, data indicate that the anti-inflammatory action of RWE is exerted at complementary levels, via suppression of the JAK/STAT inflammatory pathway and positive modulation of the activity of Nrf2. These results point to the potential use of the RWE as an efficient, readily available and inexpensive therapeutic strategy in the context of gastrointestinal inflammation.

The Role of Type I Interferon Subtypes and Interferon-Gamma in Type I Interferon Diabetes Inhibitory Activity in the NOD Mouse

As in bacterial infections and endotoxin shock, type I interferons (IFNs) also have complex and often opposing effects in various models of autoimmune disease. We have shown that type I IFN paradoxically inhibits autoimmune diabetes in the nonobese diabetic mouse (NOD) and biobreeding (BB) rat. We hypothesize that type I IFN activity differs by IFN subtype and interaction with IFN-gamma. We examined the structure-function relationship of the type I IFN molecule and the mechanism of its diabetes-sparing activity in the NOD mouse. While both recombinant human IFN-alpha A/D (bgl 11) (rHuIFN-alphaA/D) and ovine IFN-tauImod (ovIFN-tau) potently inhibited the development of diabetes (P < 0.01), neither recombinant human IFN-alpha B/D (rHuIFN-alphaB/D) nor recombinant human IFN-alpha consensus (CIFN) were efficacious. The activity of IFN subtypes correlate with their NH3-terminal amino acid sequences. All type I IFN save CIFN, which has no diabetes-sparing activity, inhibited the accessory cell function. IFN-tau administration decreased the expression of Fas and ICAM on total cells, class II MHC expression on B cells, and CD40L expression on T cells by 39%, 45%, 45%, and 60%, respectively. In addition, IFN-tau inhibited the development of diabetes in the NOD.IL4(null) but not the NOD.IFN-gamma(null) mice, suggesting a coordinated interaction between type I and type II IFNs to suppress diabetes development. Thus, the amino terminal portion of the type I IFN molecule influences its ability to inhibit the development of autoimmune diabetes in NOD mice. These data also support the contention that IFN-gamma may have a role in mediating the diabetes-sparing effect of high-dose type I IFNs by the inhibition of the IFN-gamma-inducible immune modulators, class II MHC, Fas, ICAM, and CD40L.

The effects of proinflammatory cytokines on the apoptosis of corneal endothelial cells following argon laser iridotomy

The aim of this study was to evaluate the relationship between the expression of proinflammatory cytokines and the apoptosis of corneal endothelial cells after argon laser iridotomy (ALI). ALI was performed on each quadrant of the iris in the right eye of mice (ALI1 group). Left eyes were used as control group. The levels of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-β, and interferon (IFN)-γ in mice eyes were measured, and TUNEL staining was performed 12 h after ALI. Mice in the ALI-Dexa group were pretreated daily with an intraperitoneal injection of dexamethasone for 4 days before undergoing ALI and compared with mice without dexamethasone pretreatment (ALI2 group). Twelve corneas from six rabbits were incubated ex vivo with (n = 6) or without (n = 6) IL-1β. TUNEL staining was performed 24 h after ex vivo incubation. In the mice experiment, the levels of IL-1β, TNF-α, TGF-β, and IFN-γ were increased in the ALI1 group compared to the control group. Although many TUNEL-positive cells were observed in the ALI1 group, those were not detected in the control group. Dexamethasone pretreatment inhibited the increase in the levels of all four proinflammatory cytokines and reduced TUNEL-positive cells. In the rabbit experiment, TUNEL-positive cells were increased in the incubated corneas with IL-1β compared to those without IL-1β. Expression of proinflammatory cytokines following ALI seems to play a role in the apoptosis of corneal endothelial cells after ALI. Dexamethasone pretreatment inhibited increases in proinflammatory cytokines and reduced the apoptosis of corneal endothelial cells.

STAT1 inhibits human hepatocellular carcinoma cell growth through induction of p53 and Fbxw7

Background

Aberrant STAT1 signaling is observed in human hepatocellular carcinoma (HCC) and has been associated with the modulation of cell proliferation and survival. However, the role of STAT1 signaling in HCC and its underlying mechanism remain elusive.

Methods

We transiently transfected pcDNA3.1-STAT1 and STAT1 siRNA into SMMC7721 and HepG2 cells. Western blot and qRT-PCR examined the expression of protein and RNA of target genes. Cell viability was assessed using MTT assay, and cell cycle and apoptosis were analyzed by flow cytometry.

Results

We found that STAT1 overexpression increased protein expression of p53 and Fbxw7, and downregulated the expression of cyclin A, cyclin D1, cyclin E, CDK2, Hes-1 and NF-κB p65. These changes led to growth inhibition and induced G0/G1 cell cycle arrest and apoptosis in SMMC7721 and HepG2 cells. Conversely, ablation of STAT1 had the opposite effect on p53, Fbxw7, Hes-1, NF-κB p65, cyclin A, cyclin D1, cyclin E and CDK2, and improved the viability of SMMC7721 and HepG2 cells.

Conclusions

Our data indicate that STAT1 exerts tumor-suppressive effects in hepatocarcinogenesis through induction of G0/G1 cell cycle arrest and apoptosis, and may provide a basis for the design of new therapies for the intervention of HCC in the clinic.

Interferon-γ differentially modulates the impact of tumor necrosis factor-α on human endometrial stromal cells

The pro-inflammatory T helper (Th)-1 cytokines, tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ), are immunological factors relevant at the feto-maternal interface and involved in the pathophysiology of implantation disorders. The synergistic action of the two cytokines has been described with regard to apoptotic cell death and inflammatory responses in different cell types, but little is known regarding the human endometrium. Therefore, we examined the interaction of TNF-α and IFN-γ in human endometrial stromal cells (ESCs). ESCs were isolated from specimens obtained during hysterectomy and decidualized in vitro. Cells were incubated with TNF-α, IFN-γ or signaling-inhibitor. Insulin-like growth factor binding protein (IGFBP)-1, prolactin (PRL), leukemia inhibitory factor (LIF), interleukin (IL)-6, IL-8, regulated on activation normal T-cell expressed and secreted protein (RANTES) and monocyte chemotactic protein (MCP)-1 were measured using ELISA and real-time RT-PCR. Nuclear factor of transcription (NF)-κB and its inhibitor (IκBα) were analyzed by in-cell western assay and transcription factor assay. TNF-α inhibited and IFN-γ did not affect the decidualization of ESCs. In contrast, IFN-gamma differentially modulated the stimulating effect of TNF-alpha on cytokines by enhancing IL-6, RANTES and MCP-1 and attenuating LIF mRNA expression. These effects were time- and dose-dependent. IFN-γ had no impact on the initial activation of NF-κB signaling. Histone-deacetylase activity was involved in the modulating effect of IFN-γ on RANTES secretion. These observations showed a distinct pattern of interaction of the Th-1 cytokines, TNF-α and IFN-γ in the human endometrium, which could play an important role in the pathophysiology of implantation disorders.