Alterations of peripheral CD4+CD25+Foxp3+ T regulatory cells in mice with STZ-induced diabetes. Cell Mol Immunol. 2012;9:75-85. [PMID: 21983870 DOI: 10.1038/cmi.2011.37]

Hyperglycemia Exacerbates Periodontal Destruction via Systemic Suppression of Regulatory T Cell Number and Function

AIM

Diabetes is a significant risk factor that exacerbates the pathological progression of periodontal disease. In recent years, attention has focused on the effect of regulatory T cells (Tregs), which play a central role in immune tolerance, on inflammatory processes in periodontal tissue, suggesting a link with diabetes-associated periodontitis. In this study, we examined the dynamics of Tregs in periodontal tissue of mice with streptozotocin (STZ)-induced hyperglycemia.

METHODS

Eleven-week-old male C57BL/6J mice were divided into four treatment groups: Untreated (C group), ligature placed around the maxillary second molars with silk sutures (PD group), intraperitoneal administration of STZ (HG group), and ligature placed after STZ administration (PHG group). Establishment of hyperglycemia was assessed 14 days after STZ administration, and ligation was performed 7 days later. After another 7 days of ligation, the mice were euthanized. The right side of the maxilla was observed histopathologically, whereas the palatal gingiva on the left side of the maxilla was analyzed genetically, and the microstructure of the alveolar bone was also assessed. In addition, lymphocytes from peripheral blood, spleen, and periodontal tissue were analyzed using flow cytometry.

RESULTS

In bone structure analyses, alveolar bone height, bone volume/tissue volume (BV/TV), and bone mineral density (BMD) were lower in the PHG group than the PD group. In the gingival tissue, expression of the Foxp3 gene was up-regulated in the PHG group compared with the C group, and IL-17a was up-regulated in the PHG group compared with the PD group. Flow cytometry analyses showed that the number of Tregs (CD4+CD25+Foxp3+ cells) in the blood and gingival tissue was significantly higher in the PD and PHG groups than the C group. The number of CD4+CD25-Foxp3+ cells, which are reportedly functionally attenuated as Tregs, was increased in blood of the PHG group. Immunofluorescence staining of periodontal tissue showed that the number of CD25+Foxp3+ cells was significantly increased only in the PD group, whereas a trend toward an increased number of CD25-Foxp3+ cells was observed in the PHG group.

CONCLUSION

The present study showed that STZ-induced hyperglycemia numerically and functionally attenuates Tregs in a mouse model of experimental periodontitis. Furthermore, impaired immune tolerance capacity appears to be involved in exacerbating inflammation and bone destruction in periodontal tissue.

Assessing the effectiveness of Interleukin-2 therapy in experimental type 1 diabetes

AIM

Much focus of immunotherapy for type 1 diabetes (T1D) has been devoted on selectively boosting regulatory T (Treg) cells using low dose IL-2 due to their constitutive expression of IL-2Rα, CD25. However, several clinical trials using a low dose of IL-2 only showed a limited improvement of metabolic control. It can therefore be hypothesized that further decreasing IL-2 dosage may increase the selective responsiveness of Treg cells.

METHODS

We induced experimental T1D using multiple low dose streptozotocin (STZ) injections and treated the mice with an ultra-low dose IL-2 (uIL-2, approximately 7-fold lower than low dose). Immune response was studied using multicolor flow cytometry.

RESULTS

We found that uIL-2 did not protect STZ mice from developing hyperglycemia. It did neither increase Treg cell proportions, nor did it correct the phenotypic shift of Treg cells seen in T1D. It only partially decreased the proportion of IFN-γ+ T cells. Likewise, uIL-2 also did not protect the dysfunction of regulatory B (Breg) cells. Strikingly, when administered in combination with an anti-inflammatory cytokine IL-35, uIL-2 abrogated IL-35's protective effect. Low dose IL-2, on the other hand, protected half of the STZ mice from developing hyperglycemia. No difference was found in the Treg and Breg response, and it only tended to decrease CD80 expression in macrophages and dendritic cells.

CONCLUSION

In conclusion, further decreasing IL-2 dosage may not be a suitable approach for T1D therapy, and the limited success suggests that an alternative low dose IL-2 therapy strategy or other immunotherapies should be considered.

Autoimmune uveitis attenuated in diabetic mice through imbalance of Th1/Th17 differentiation via suppression of AP-1 signaling pathway in Th cells

Purpose

Inflammation is involved in the pathogenesis of diabetes, however the impact of diabetes on organ-specific autoimmune diseases remains unexplored. Experimental autoimmune uveoretinitis (EAU) is a widely accepted animal model of human endogenous uveitis. In this study, we investigated the effects of diabetic conditions on the development of EAU using a mouse diabetes model.

Methods

EAU was induced in wild-type C57BL/6 (WT) mice and Ins2Akita (Akita) mice with spontaneous diabetes by immunization with IRBP peptide. Clinical and histopathological examinations, and analysis of T cell activation state were conducted. In addition, alternations in the composition of immune cell types and gene expression profiles of relevant immune functions were identified using single-cell RNA sequencing.

Results

The development of EAU was significantly attenuated in immunized Akita (Akita-EAU) mice compared with immunized WT (WT-EAU) mice, although T cells were fully activated in Akita-EAU mice, and the differentiation into Th17 cells and regulatory T (Treg) cells was promoted. However, Th1 cell differentiation was inhibited in Akita-EAU mice, and single-cell analysis indicated that gene expression associated AP-1 signaling pathway (JUN, FOS, and FOSB) was downregulated not only in Th1 cells but also in Th17, and Treg cells in Akita-EAU mice at the onset of EAU.

Conclusions

In diabetic mice, EAU was significantly attenuated. This was related to selective inhibition of Th1 cell differentiation and downregulated AP-1 signaling pathway in both Th1 and Th17 cells.

Oxidative stress as a culprit in diabetic kidney disease

Diabetic kidney disease (DKD) has become the leading cause of end-stage renal disease (ESRD), and the prevalence of DKD has increased worldwide during recent years. DKD is associated with poor therapeutic outcomes in most patients, but there is limited understanding of its pathogenesis. This review suggests that oxidative stress interacts with many other factors in causing DKD. Highly active mitochondria and NAD(P)H oxidase are major sources of oxidants, and they significantly affect the risk for DKD. Oxidative stress and inflammation may be considered reciprocal causes of DKD, in that each is a cause and an effect of DKD. Reactive oxygen species (ROS) can act as second messengers in various signaling pathways and as regulators of metabolism, activation, proliferation, differentiation, and apoptosis of immune cells. Epigenetic modifications, such as DNA methylation, histone modifications, and non-coding RNAs can modulate oxidative stress. The development of new technologies and identification of new epigenetic mechanisms may provide novel opportunities for the diagnosis and treatment of DKD. Clinical trials demonstrated that novel therapies which reduce oxidative stress can slow the progression of DKD. These therapies include the NRF2 activator bardoxolone methyl, new blood glucose-lowering drugs such as sodium-glucose cotransporter 2 inhibitors, and glucagon-like peptide-1 receptor agonists. Future studies should focus on improving early diagnosis and the development of more effective combination treatments for this multifactorial disease.

Anti-Inflammatory Effects of Melatonin in Rats with Induced Type 2 Diabetes Mellitus

Introduction: Insulin resistance is associated with a pro-inflammatory state increasing the risk for complications in patients with type 2 diabetes mellitus (T2DM). In addition to its chronobiotic effects, the pineal hormone melatonin is known to exert anti-inflammatory and antioxidant effects. Melatonin was also suggested to affect insulin secretion. The aim of this study was therefore to investigate the effect of melatonin on inflammation in diabetic rats and to study the possible involvement of the melatonin receptor, MT2. Materials and Methods: Male Sprague Dawley rats were randomly divided into four experimental groups (n = 10 per group): (1) control, (2) streptozotocin/nicotinamide induced diabetes type 2 (T2DM), (3) T2DM treated with melatonin (500 µg/kg/day), and (4) T2DM treated with melatonin (500 µg/kg/day for 6 weeks) and the selective MT2 receptor antagonist luzindole (0.25 g/kg/day for 6 weeks). Blood samples were taken for biochemical parameters and various tissue samples (liver, adipose tissue, brain) were removed for immunohistochemistry (IHC), Western blot (WB), and Q-PCR analyses, respectively. Results: Melatonin significantly reduced increased blood levels of liver transaminases (AST, ALT), blood urea nitrogen (BUN), triglyceride, very low-density lipoprotein (VLDL), and cholesterol in diabetic rats with luzindole treatment partly reversing this effect regarding the lipids. Furthermore, the liver and adipose tissues of T2DM rats treated with melatonin showed lower expression of the inflammatory markers IL-1β, IL-6, TNF-α, and NF-κB as compared to the T2DM group without melatonin. The results also showed that the MT2 receptor is at least partly involved in the protective effects of melatonin. Conclusions: Our results suggest that melatonin exerts relevant anti-inflammatory effects on various tissues in type 2 diabetic rats.

Antiparasitic and immunomodulating effects of nitazoxanide, ivermectin and selenium on Cryptosporidium infection in diabetic mice

The present work aims to investigate the antiparasitic and the immunomodulating effects of nitazoxanide (NTZ) and ivermectin (IVC) alone or combined together or combined with selenium (Se), on Cryptosporidium infection in diabetic mice. The results revealed that the combined NTZ and IVC therapy achieved the highest reduction of fecal oocysts (92%), whereas single NTZ showed the lowest reduction (63%). Also, adding Se to either NTZ or IVC resulted in elevation of oocyst reduction from 63% to 71% and from 82% to 84% respectively. All treatment regimens, with the exception of NTZ monotherapy, showed a significant improvement in the intestinal histopathology, the highest score was in combined NTZ and IVC therapy. The unique results of immunohistochemistry in this study showed reversal of the normal CD4/CD8 T cell ratio in the infected untreated mice, however, following therapy it reverts back to a normal balanced ratio. The combined (NTZ+ IVC) treatment demonstrated the highest level of CD4 T cell expression. Taken together, NTZ and IVC combined therapy showed remarkable anti-parasitic and immunostimulatory effects, specifically towards the CD4 population that seem to be promising in controlling cryptosporidiosis in diabetic individuals. Further research is required to explore other effective treatment strategies for those comorbid patients.

Diabetes mellitus exacerbates experimental autoimmune myasthenia gravis via modulating both adaptive and innate immunity

BACKGROUND

Diabetes mellitus (DM) is a common concomitant disease of late-onset myasthenia gravis (MG). However, the impacts of DM on the progression of late-onset MG were unclear.

METHODS

In this study, we examined the immune response in experimental autoimmune myasthenia gravis (EAMG) rats with DM or not. The phenotype and function of the spleen and lymph nodes were determined by flow cytometry. The serum antibodies, Tfh cells, and germinal center B cells were determined by ELISA and flow cytometry. The roles of advanced glycation end products (AGEs) in regulating Tfh cells were further explored in vitro by co-culture assays.

RESULTS

Our results indicated clinical scores of EAMG rats were worse in diabetes rats compared to control, which was due to the increased production of anti-R97-116 antibody and antibody-secreting cells. Furthermore, diabetes induced a significant upregulation of Tfh cells and the subtypes of Tfh1 and Tfh17 cells to provide assistance for antibody production. The total percentages of B cells were increased with an activated statue of improved expression of costimulatory molecules CD80 and CD86. We found CD4⁺ T-cell differentiation was shifted from Treg cells towards Th1/Th17 in the DM+EAMG group compared to the EAMG group. In addition, in innate immunity, diabetic EAMG rats displayed more CXCR5 expression on NK cells. However, the expression of CXCR5 on NKT cells was down-regulated with the increased percentages of NKT cells in the DM+EAMG group. Ex vivo studies further indicated that Tfh cells were upregulated by AGEs instead of hyperglycemia. The upregulation was mediated by the existence of B cells, the mechanism of which might be attributed the elevated molecule CD40 on B cells.

CONCLUSIONS

Diabetes promoted both adaptive and innate immunity and exacerbated clinical symptoms in EAMG rats. Considering the effect of diabetes, therapy in reducing blood glucose levels in MG patients might improve clinical efficacy through suppressing the both innate and adaptive immune responses. Additional studies are needed to confirm the effect of glucose or AGEs reduction to seek treatment for MG.

Altered Renal Pathology in an Autoimmune Disease Mouse Model After Induction of Diabetes Mellitus

Diabetes mellitus (DM) is a predisposing factor for renal disorder progression and is referred to as diabetic kidney disease (DKD). However, there are no reports of DKD with an underlying autoimmune disorder. In this study, we compared the pathophysiological changes caused by DM induction after streptozotocin (STZ) injection in comparison with that in a control group receiving citrate buffer (CB) in the autoimmune disease model mice “BXSB/MpJ-Yaa” (Yaa) and the wild-type strain BXSB/MpJ. Both strains showed hyperglycemia after 12 weeks of STZ injection. Interestingly, the Yaa group developed membranous and proliferative glomerulonephritis, which tended to be milder glomerular lesions in the STZ group than in the CB group, as indicated by a decreased mesangial area and ameliorated albuminuria. Statistically, the indices for hyperglycemia and autoimmune abnormalities were negatively and positively correlated with the histopathological parameters for mesangial matrix production and glomerular proliferative lesions, respectively. STZ treatment induced renal tubular anisonucleosis and dilations in both strains, and they were more severe in Yaa. Significantly decreased cellular infiltration was observed in the Yaa group compared to the CB group. Thus, in DKD related to autoimmune nephritis, hyperglycemia modifies its pathology by decreasing the mesangial area and interstitial inflammation and aggravating renal tubular injury.

Regulatory T Cells and Diabetes Mellitus

Immune system dysfunction causes dysregulation of immune homeostasis, which in turn leads to autoimmune diseases. Regulatory T cells (Tregs) are a specialized T cell subpopulation that maintain peripheral tolerance and immune homeostasis. Diabetic patients are at an increased risk of developing cardiovascular diseases; thus, in terms of coronary risk, diabetes mellitus (DM) is considered coronary heart disease equivalent. Accumulating evidence indicates that Tregs play an important role in protecting against the development of various cardiovascular diseases. In this review, we provide an overview of the role of Tregs in the pathogenesis of DM, including type 1 DM, type 2 DM, latent autoimmune diabetes of adults, and gestational DM. In addition, we discuss the role of Tregs in diabetic complications, including cardiovascular diseases, nephropathy, neuropathy, and retinopathy. Tregs play a beneficial role in the pathogenesis of DM and diabetic complications, although the precise molecular mechanisms underlying the protective effect of Tregs against DM are still obscure. Collectively, modification of Tregs may provide a promising and novel future strategy for the prevention and therapy of DM and diabetic complications.

Negative regulation of FOXP3 expression by c-Rel O-GlcNAcylation

O-GlcNAcylation is a reversible post-translational protein modification that regulates fundamental cellular processes including immune responses and autoimmunity. Previously, we showed that hyperglycemia increases O-GlcNAcylation of the transcription factor, nuclear factor kappaB c-Rel at serine residue 350 and enhances the transcription of the c-Rel-dependent proautoimmune cytokines interleukin-2, interferon gamma and granulocyte macrophage colony stimulating factor in T cells. c-Rel also plays a critical role in the transcriptional regulation of forkhead box P3 (FOXP3)-the master transcription factor that governs development and function of Treg cells. Here we show that the regulatory effect of c-Rel O-GlcNAcylation is gene-dependent, and in contrast to its role in enhancing the expression of proautoimmune cytokines, it suppresses the expression of FOXP3. Hyperglycemia-induced O-GlcNAcylation-dependent suppression of FOXP3 expression was found in vivo in two mouse models of autoimmune diabetes; streptozotocin-induced diabetes and spontaneous diabetes in nonobese diabetic mice. Mechanistically, we show that both hyperglycemia-induced and chemically enhanced cellular O-GlcNAcylation decreases c-Rel binding at the FOXP3 promoter and negatively regulates FOXP3 expression. Mutation of the O-GlcNAcylation site in c-Rel, (serine 350 to alanine), augments T cell receptor-induced FOXP3 expression and resists the O-GlcNAcylation-dependent repression of FOXP3 expression. This study reveals c-Rel S350 O-GlcNAcylation as a novel molecular mechanism inversely regulating immunosuppressive FOXP3 expression and proautoimmune gene expression in autoimmune diabetes with potential therapeutic implications.

Cell Based Therapy for Type 1 Diabetes: Should We Take Hyperglycemia Into Account?

Diabetes mellitus is characterized by long standing hyperglycemia leading to numerous life-threatening complications. For type 1 diabetes mellitus, resulting from selective destruction of insulin producing cells by exaggerated immune reaction, the only effective therapy remains exogenous insulin administration. Despite accurate compliance to treatment of certain patients, transient episodes of hyperglycemia cannot be completely eliminated by this symptomatic treatment. Novel immunotherapeutic approaches based on tolerogenic dendritic cells, T regulatory cells and mesenchymal stem cells (MSCs) have been tested in clinical trials, endeavoring to directly modulate the autoimmune destruction process in pancreas. However, hyperglycemia itself affects the immune system and the final efficacy of cell-based immunotherapies could be affected by the different glycemic control of enrolled patients. The present review explores the impact of hyperglycemia on immune cells while providing greater insight into the molecular mechanisms of high glucose action and subsequent metabolic reprogramming of different immune cells. Furthermore, over-production of mitochondrial reactive oxygen species, formation of advanced glycation end products as a consequence of hyperglycemia and their downstream signalization in immune cells are also discussed. Since hyperglycemia in patients with type 1 diabetes mellitus might have an impact on immune-interventional treatment, the maintenance of a tight glucose control seems to be beneficial in patients considered for cell-based therapy.

Immune and vascular dysfunction in diabetic wound healing

The diminished capacity for wound healing in patients with diabetes contributes to morbidity through ulceration and recurrent infections, loss of function and decreased workplace productivity, increased hospitalisation rates, and rising health-care costs. These are due to diabetes' effects on signalling molecules, cellular cascades, different cell populations, and the vasculature. The function of multiple immune system components including cellular response, blood factors, and vascular tone are all negatively impacted by diabetes. The purpose of this paper is to review the current understanding of immune and vascular dysfunction contributing to impaired wound healing mechanisms in the diabetic population. Normal wound healing mechanisms are reviewed followed by diabetic aberrations to immune and inflammatory function and atherogenesis and angiopathy.

DECLARATION OF INTEREST

The authors have no financial or personal relationships to people or organisations that could potentially and inappropriately influence their work and conclusions.

Impact of hyperglycemia on autoimmune pancreatitis and regulatory T-cells

AIM

To evaluate the influence of hyperglycemia on the progression of autoimmune pancreatitis.

METHODS

We induced hyperglycemia by repetitive intraperitoneal (ip) injection of 50 mg/kg streptozotocin in MRL/MpJ mice, which develop autoimmune pancreatitis due to a genetic predisposition. We compared the extent of inflammation (histological score, CD3+ lymphocytes, CD8+ T-cells, CD4+ T-cells, Foxp3+ T-helper cells) in the pancreas of hyperglycemic and normoglycemic mice. We also analyzed the number of leukocytes, lymphocytes, granulocytes and monocytes in the blood. In addition, we determined the percentage of CD3+ lymphocytes, CD8+ T-cells, CD4+ T-cells, Foxp3+ T-helper cells, Foxp3+ CD25+ T-helper and Foxp3- T-helper cells in the spleen by flow cytometry.

RESULTS

Treatment with streptozotocin caused a strong induction of hyperglycemia and a reduction in body weight (P < 0.001). Severe hyperglycemia did not, however, lead to an aggravation, but rather to a slight attenuation of autoimmune pancreatitis. In the pancreas, both the histological score of the pancreas as well as the number of CD3+ lymphocytes (P < 0.053) were decreased by hyperglycemia. No major changes in the percentage of CD8+ T-cells, CD4+ T-cells, Foxp3+ T-helper cells were observed between hyperglycemic and normoglycemic mice. Hyperglycemia increased the numbers of leukocytes (P < 0.001), lymphocytes (P = 0.016), granulocytes and monocytes (P = 0.001) in the blood. Hyperglycemia also moderately reduced the percentage of CD3+ lymphocytes (P = 0.057), significantly increased the percentage of Foxp3+ T-helper cells (P = 0.018) and Foxp3+ CD25+ T-helper cells (P = 0.021) and reduced the percentage of Foxp3- T-helper cells (P = 0.034) in the spleen.

CONCLUSION

Hyperglycemia does not aggravate but moderately attenuates autoimmune pancreatitis, possibly by increasing the percentage of regulatory T-cells in the spleen.

Polysaccharides from Chinese Herbal Lycium barbarum Induced Systemic and Local Immune Responses in H22 Tumor-Bearing Mice

Lycium barbarum polysaccharide (LBP) is isolated from the fruit of Chinese herbal Lycium barbarum. Previous studies had demonstrated that LBP could inhibit tumor growth and enhance the immunity in mice. However, the effect of LBP on systemic and local immune responses in vivo, especially on phenotypic and functional changes of T cells, is still largely unknown. In the present study, we investigated the effects of LBP on systemic and local T cell-dependent antitumor immune responses in H22 tumor-bearing mice. The results showed that LBP could inhibit the solid tumor growth in mice, but showed little effect on the body weight or spleen index. Furthermore, LBP could maintain high levels of T cells in peripheral blood (PB), tumor draining lymph node (TDLN), and tumor tissue, prevent the increase of Tregs while promote infiltration of CD8+ T cells in tumor tissue, inhibit the production of TGF-β1 and IL-10 in serum, decrease the exhaustion phenotype of T cells, and maintain cytotoxicity of lymphocytes. Taken together, our results demonstrated that LBP simultaneously induced systemic and local immune responses in H22 tumor-bearing mice by alleviating immunosuppression and maintaining antitumor immune responses in mice.

Exendin-4 Exhibits Enhanced Anti-tumor Effects in Diabetic Mice

Type 2 diabetes (T2D) is associated with increased risk of cancers. In this connection, we previously demonstrated the promoting effect of diabetes on HPV-associated carcinogenesis using a xenograft model in db/db diabetic mice. The underlying mechanism of this observation might be partly contributed by dysregulated immune response in diabetes. In this study, we hypothesized that the impaired anti-tumor immune response in diabetic status could be modulated by exendin-4, a glucagon-like protein receptor agonist which exhibits anti-diabetic effects. We inoculated 10-week old db/db mice with 2 × 10⁷ CUP-1 cells (Human Papilloma Virus (HPV)-16 E7 transfected continuous cell line) subcutaneously underneath the scruff, and treated mice with high (30 nmol/kg) or low (10 nmol/kg) dose of exendin-4 for 13 days. Compared with control groups, exendin-4 suppressed subcutaneous tumor growth in a dose-dependent manner, accompanied by increased interferon (IFN)-γ secreting CD8⁺ cytotoxic T lymphocyte (CTL)/Foxp3⁺ regulatory T cell (Treg) ratio as well as Th1 proinflammatory cytokines IFN-γ and IL-2. Collectively, these findings suggested an anti-tumor effect of exendin-4 in diabetic conditions, which might be resulted from direct immunomodulation.

T regulatory lymphocytes in type 1 diabetes: Impaired CD25 expression and IL-2 induced STAT5 phosphorylation in pediatric patients

T regulatory cells (Tregs) are essential for maintaining tolerance and preventing autoimmune diseases, such as type 1 diabetes (T1D). In our study, we investigated CD25 + FoxP3 + Tregs and thymic FoxP3 + Helios + Tregs in large cohorts of children with T1D at onset and with long-term T1D, and further in their relatives and healthy controls. We observed significantly decreased numbers of CD25 + FoxP3 + Tregs, but not FoxP3 + Helios + Tregs, in long-term patients compared with the control group and T1D onset. Furthermore, long-term T1D patients exhibited highly significant decrease of CD25 expression on both CD25 + FoxP3 + Tregs and FoxP3 + Helios + Tregs, independently on age or the duration of diabetes. A similar reduction of CD25 expression was also found in T1D relatives, more significant in those with positive autoantibodies. Low CD25 expression was associated with impaired signal transducer and activator of transcription 5 (STAT5) phosphorylation after IL-2 exposure. Our results show that the frequency of Tregs is altered in a large cohort of long-term T1D patients, a profound decrease in CD25 expression and altered IL-2 signaling are typical features of Tregs populations in long-term diabetic patients and their relatives.

Hepatic immunophenotyping for streptozotocin-induced hyperglycemia in mice

Emerging evidence revealed that diabetes induces abnormal immune responses that result in serious complications in organs. However, the effect of hyperglycemia on hepatic immunity remains obscure. We evaluated the population and function of hepatic immune cells in streptozotocin (STZ)-induced hyperglycemic mice. CC chemokine receptor 2 (CCR2)-knockout mice and mice with a depletion of regulatory T cells (DEREG) were used to investigate the migration and role of regulatory T cells (Tregs) in hyperglycemic mice. The inflammatory cytokines and hepatic transaminase levels were significantly increased in the hyperglycemic mice. The population and number of infiltrating monocytes, granulocytes, and Tregs were enhanced in the livers of the hyperglycemic mice. Hepatic monocytes other than macrophages showed the increased expression of inflammatory cytokines and chemokines in the hyperglycemic mice. The CCR2 knockout and DEREG chimeric mice exhibited increased populations of activated T cells and neutrophils compared to the WT chimeric mice, which promoted hepatic inflammation in the hyperglycemic mice. The migration of CCR2 knockout Tregs into the liver was significantly reduced compared to the WT Tregs. We demonstrated that hyperglycemia contributes to increase in infiltrating monocytes and Tregs, which are associated with hepatic immune dysfunction in mice. CCR2-mediated migration of Tregs regulates hyperglycemia-induced hepatic inflammation.

Regulatory role of natural killer T cells in diabetes

Type 1 and type 2 diabetes are growing public health problems. Despite having different pathophysiologies, both diseases are associated with defects in immune regulation. Invariant natural killer T (iNKT) cells are innate-like T cells that recognize glycolipids presented by CD1d. These cells not only play a key role in the defense against pathogens, but also exert potent immunoregulatory functions. The regulatory role of iNKT cells in the prevention of type 1 diabetes has been demonstrated in murine models and analyzed in diabetic patients. The decreased frequency of iNKT cells in non-obese diabetic mice initially suggested the regulatory role of this cell subset. Increasing the frequency or the activation of iNKT cells with agonists protects non-obese diabetic mice from the development of diabetes. Several mechanisms mediate iNKT regulatory functions. They can rapidly produce immunoregulatory cytokines, interleukin (IL)-4 and IL-10. They induce tolerogenic dendritic cells, thereby inducing the anergy of autoreactive anti-islet T cells and increasing the frequency of T regulatory cells (Treg cells). Synthetic agonists are able to activate iNKT cells and represent potential therapeutic treatment in order to prevent type 1 diabetes. Growing evidence points to a role of immune system in glucose intolerance and type 2 diabetes. iNKT cells are resident cells of adipose tissue and their local and systemic frequencies are reduced in obese patients, suggesting their involvement in local and systemic inflammation during obesity. With the discovery of potential continuity between type 1 and type 2 diabetes in some patients, the role of iNKT cells in these diseases deserves further investigation.

Indirubin Increases CD4+CD25+Foxp3+ Regulatory T Cells to Prevent Immune Thrombocytopenia in Mice

Indirubin, a traditional Chinese medicine, is used to treat autoimmune diseases in clinics. However, the effects of indirubin on the immunosuppressive CD4+CD25+Foxp3+ regulatory T cells (Treg) have not been addressed. Thus, we aimed to investigate the effects of indirubin on CD4+CD25+Treg cells in immune thrombocytopenia (ITP) CBA mice, which were established by immunization with Wistar rat platelets. 50 mg/kg indirubin treatment daily for 4 weeks significantly decreased anti-platelet antibody production and prevented the decrease of platelets caused by immunization in ITP mice. Consistently, indirubin significantly enhanced the percentage and cell number of CD4+CD25+Foxp3+Treg cells in the peripheral blood, spleen and lymph nodes. We also observed a significant increase of the frequency and cell number of CD4+CD25+Foxp3+Treg cells in the thymus upon indirubin treatment. Furthermore, CD4+CD25+Treg cells from indirubin-treated mice showed similar immunosuppression on T effector cells as compared to those from control mice. Altogether, indirubin ameliorates ITP by enhancing CD4+CD25+Foxp3+Treg cell level with preserving immunosuppressive function.

Resistance of spontaneously diabetic Ins2(akita) mice to allograft tolerance induced by anti-CD154 therapy

BACKGROUND

Despite ongoing advances in the clinical islet transplant field, progressive decline in graft function continues to reduce the long-term success of islet transplantation for restoring euglycemia in type 1 diabetic recipients. To preserve graft function and avoid the use of chronic immunosuppressive drug therapy, a key goal is to induce donor-specific immune tolerance to islet transplants. Preclinical rodent studies of islet transplantation largely utilize models of diabetes either induced experimentally with beta cell toxins or spontaneously occurring in strains genetically prone to autoimmune diabetes. In this study, we sought to determine if chronic, severe hyperglycemia itself, independent of both beta cell toxins and host autoimmunity, influenced acute allograft rejection and/or the capacity to induce allograft tolerance.

METHOD

To this end, we studied the response to islet allografts in severely diabetic, non-autoimmune C57Bl/6 Ins2(akita) recipients.

RESULTS

Results indicate that diabetic Ins2(akita) mice display higher levels of blood glucose, show more rapid acute islet allograft rejection, and are resistant to allograft prolongation induced with anti-CD154 therapy relative to wild-type littermates rendered diabetic with streptozotocin. As such, results suggest that severe hyperglycemia may be an independent risk factor impacting the capacity to induce tolerance to islet allografts. Thus, Ins2(akita) mice represent a stringent model for evaluating anti-rejection strategies in the setting of severe metabolic demand on islet transplants.

Regulatory Role of Natural Killer T Cells in Diabetes

Type 1 and type 2 diabetes are growing public health problems. Despite having different pathophysiologies, both diseases are associated with defects in immune regulation. Invariant natural killer T (iNKT) cells are innate-like T cells that recognize glycolipids presented by CD1d. These cells not only play a key role in the defense against pathogens, but also exert potent immunoregulatory functions. The regulatory role of iNKT cells in the prevention of type 1 diabetes has been demonstrated in murine models and analyzed in diabetic patients. The decreased frequency of iNKT cells in non-obese diabetic mice initially suggested the regulatory role of this cell subset. Increasing the frequency or the activation of iNKT cells with agonists protects non-obese diabetic mice from the development of diabetes. Several mechanisms mediate iNKT regulatory functions. They can rapidly produce immunoregulatory cytokines, interleukin (IL)-4 and IL-10. They induce tolerogenic dendritic cells, thereby inducing the anergy of autoreactive anti-islet T cells and increasing the frequency of T regulatory cells (Treg cells). Synthetic agonists are able to activate iNKT cells and represent potential therapeutic treatment in order to prevent type 1 diabetes. Growing evidence points to a role of immune system in glucose intolerance and type 2 diabetes. iNKT cells are resident cells of adipose tissue and their local and systemic frequencies are reduced in obese patients, suggesting their involvement in local and systemic inflammation during obesity. With the discovery of potential continuity between type 1 and type 2 diabetes in some patients, the role of iNKT cells in these diseases deserves further investigation.

Advances in understanding relationship between peripheral blood CD4+CD25+ regulatory T cells and antiviral treatment in CHB patients

The immunosuppressive function of CD4⁺ CD25⁺ regulatory T cells may closely associate with the occurrence, development and prognosis of CHB patients. The change and function of CD4⁺CD25⁺ regulatory T cells in CHB patients undergoing antiviral treatment have aroused the attention of scholars. Here we review the types, immunophenotypes, and function of CD4⁺CD25⁺ regulatory T cells, as well as the relationship between peripheral blood CD4⁺CD25⁺ regulatory T cells and antiviral treatment in CHB patients.

Could T cells be involved in lung deterioration and hyperglycemia in cystic fibrosis?

Cystic fibrosis-related diabetes (CFRD) is the most frequent complication of cystic fibrosis (CF) and associated with increased mortality. Why patients have an accelerated loss of lung function before the diagnosis of CFRD remains poorly understood. We reported that patients with or without CFRD had increased glucose excursions when compared to healthy peers. Studies have demonstrated that patients with CF have increased glucose fluctuations and hyperglycemia and that this may affect the clinical course of CF and lead to lymphocyte dysfunction. T-helper 17 (Th17) lymphocytes produce and secrete the pro-inflammatory cytokine IL-17. The Th17 pathway is involved in CF lung inflammation, β-cell destruction in type 1 diabetes (T1D) and Th17 cells of patients with type 2 diabetes have increased production of IL-17 when compared to healthy peers. Also, regulatory T-cells (Tregs) have been shown to be dysfunctional and produce IL-17 in T1D. Furthermore, vitamin D can affect inflammation in CF, diabetes and the differentiation of lymphocytes. In this review, we discuss the potential roles of hyperglycemia on Th17 cells, Tregs and IL-17 as a potential cause for accelerated lung function decline before CFRD and how this could be modulated by vitamin D or by directly intervening in the IL-17A pathway.

Statin therapy may prevent development of tuberculosis in diabetic state

Host cholesterol is widely getting recognized as an important factor in the pathogenesis of tuberculosis in multiple ways. Therefore it is logically expected that cholesterol reduction by statins is going to have a positive outcome in the context of tuberculosis management. But at the present moment statin therapy in non diabetic individuals is believed to pose a small risk for development of diabetes mellitus, a prevalent disease throughout the globe that is known to be associated with tuberculosis infection. Consequently, in diabetic individuals statins are commonly prescribed drugs for multiple positive outcomes. Therefore it seems that statin therapy in diabetes mellitus has the potential to prevent the increased occurrence of tuberculosis in diabetic state.

Differential control of Helios(+/-) Treg development by monocyte subsets through disparate inflammatory cytokines

Foxp3(+) regulatory T cells (Tregs) play a pivotal role in control of autoimmunity and pathological immune responses. Helios, the Ikarus family transcription factor, binds to the Foxp3 promoter, stabilizing its expression, and is expressed in 70% of peripheral Tregs of healthy individuals. This frequency is altered during malignancy, infection, and autoimmunity, although the mechanisms that control proliferation and relative numbers of Helios(+/-) Tregs remain largely unknown. Using a T-cell-monocyte in vitro stimulation assay, we now show that proliferation of Helios(+) Tregs is inhibited by CD16(+) monocyte subset. Antibody blocking with anti-interleukin (IL)-12 reversed this inhibition, whereas addition of IL-12 suppressed Helios(+) Treg expansion, indicating that CD16(+) monocyte control of Helios(+) Treg numbers is mediated through IL-12. In contrast, proliferation of Helios(-) Tregs, which express higher levels of tumor necrosis factor receptor II (TNFRII), was suppressed by TNF-α, whereas anti-TNF-α and anti-TNFRII reversed the inhibition. CD16(-) monocyte subset was mainly responsible for TNF-α-mediated control of Helios(-) Treg expansion. Altogether, these data suggest a differential role for monocyte subsets in control of Helios(+/-) Treg development that is mediated by distinct inflammatory cytokines. These data may have important implications for understanding the pathogenesis as well as control of chronic inflammatory and autoimmune diseases.

Inflammation in diabetic nephropathy

Diabetic nephropathy is the leading cause of end-stage kidney disease worldwide but current treatments remain suboptimal. This review examines the evidence for inflammation in the development and progression of diabetic nephropathy in both experimental and human diabetes, and provides an update on recent novel experimental approaches targeting inflammation and the lessons we have learned from these approaches. We highlight the important role of inflammatory cells in the kidney, particularly infiltrating macrophages, T-lymphocytes and the subpopulation of regulatory T cells. The possible link between immune deposition and diabetic nephropathy is explored, along with the recently described immune complexes of anti-oxidized low-density lipoproteins. We also briefly discuss some of the major inflammatory cytokines involved in the pathogenesis of diabetic nephropathy, including the role of adipokines. Lastly, we present the latest data on the pathogenic role of the stress-activated protein kinases in diabetic nephropathy, from studies on the p38 mitogen activated protein kinase and the c-Jun amino terminal kinase cell signalling pathways. The genetic and pharmacological approaches which reduce inflammation in diabetic nephropathy have not only enhanced our understanding of the pathophysiology of the disease but shown promise as potential therapeutic strategies.