The increased T helper cells proliferation and inflammatory responses in patients with type 2 diabetes mellitus is suppressed by sitagliptin and vitamin D3 in vitro

Effect of sitagliptin therapy on IL-29 and its associated signaling molecules in patients with type 2 diabetes mellitus

OBJECTIVE

The potential immunoregulatory capacity of sitagliptin on interleukin-29 (IL-29) and genes involved in its intracellular pathway were explored in type 2 diabetes mellitus (T2D).

MATERIALS AND METHODS

T2D patients treated with six months of sitagliptin (Sita+), patients not treated with sitagliptin (Sita-), and healthy controls (HCs) were included. IL-29 levels in the supernatant of stimulated mononuclear immune cells was determined with ELISA. The mRNA expression levels of IL-29, FOS, JUN, NF-AT2, NF-KB1, STAT1-2, IRF1, IRF3, IRF7, and IRF9 was assessed with real-time qPCR.

RESULTS

Increased protein and gene levels of IL-29 were observed in Sita- group compared to HCs (p < 0.001 and p = 0.026), while those levels were diminished in Sita+ group in comparison with Sita- group (p < 0.001 and p = 0.008). Expression of FOS, NF-AT2 and NF-KB1 in Sita- patients was higher than HCs (p = 0.018, p = 0.021, and p = 0.001). A significant decrease in expression of FOS, NF-AT2, and NF-KB1 was found in Sita+ group versus Sita- parients (p = 0.027, p = 0.003, and p = 0.002). In Sita- patients, IL-29 levels were correlated to glucose metabolism parameters including FPG and HbA1c (p < 0.05 for all).

CONCLUSION

Sitagliptin administration has a regulatory effect on the aggressive expression of IL-29 and its signaling molecules including FOS, NF-AT2 and NF-KB1 in T2D.

Vitamin D and Cardiovascular Diseases: From Physiology to Pathophysiology and Outcomes

Vitamin D is rightly recognized as an essential key factor in the regulation of calcium and phosphate homeostasis, affecting primary adequate bone mineralization. In the last decades, a more complex and wider role of vitamin D has been postulated and demonstrated. Cardiovascular diseases have been found to be strongly related to vitamin D levels, especially to its deficiency. Pre-clinical studies have suggested a direct role of vitamin D in the regulation of several pathophysiological pathways, such as endothelial dysfunction and platelet aggregation; moreover, observational data have confirmed the relationship with different conditions, including coronary artery disease, heart failure, and hypertension. Despite the significant evidence available so far, most clinical trials have failed to prove any positive impact of vitamin D supplements on cardiovascular outcomes. This discrepancy indicates the need for further information and knowledge about vitamin D metabolism and its effect on the cardiovascular system, in order to identify those patients who would benefit from vitamin D supplementation.

Benefits and risks of drug combination therapy for diabetes mellitus and its complications: a comprehensive review

Diabetes is a chronic metabolic disease, and its therapeutic goals focus on the effective management of blood glucose and various complications. Drug combination therapy has emerged as a comprehensive treatment approach for diabetes. An increasing number of studies have shown that, compared with monotherapy, combination therapy can bring significant clinical benefits while controlling blood glucose, weight, and blood pressure, as well as mitigating damage from certain complications and delaying their progression in diabetes, including both type 1 diabetes (T1D), type 2 diabetes (T2D) and related complications. This evidence provides strong support for the recommendation of combination therapy for diabetes and highlights the importance of combined treatment. In this review, we first provided a brief overview of the phenotype and pathogenesis of diabetes and discussed several conventional anti-diabetic medications currently used for the treatment of diabetes. We then reviewed several clinical trials and pre-clinical animal experiments on T1D, T2D, and their common complications to evaluate the efficacy and safety of different classes of drug combinations. In general, combination therapy plays a pivotal role in the management of diabetes. Integrating the effectiveness of multiple drugs enables more comprehensive and effective control of blood glucose without increasing the risk of hypoglycemia or other serious adverse events. However, specific treatment regimens should be tailored to individual patients and implemented under the guidance of healthcare professionals.

Immunomodulatory activity of dipeptidyl peptidase-4 inhibitors in immune-related diseases

Dipeptidyl peptidase-4 (DPP-4), also known as CD26, is a 110-kDa cell surface glycoprotein with enzymatic and signal transducing activity. DPP-4/CD26 is expressed by various cells, including CD4+ and CD8+ T cells, B cells, dendritic cells, macrophages, and NK cells. DPP-4 inhibitors (DPP-4i) were introduced to clinics in 2006 as new oral antihyperglycemic drugs approved for type 2 diabetes mellitus treatment. In addition to glucose-lowering effects, emerging data, from clinical studies and their animal models, suggest that DPP-4i could display anti-inflammatory and immunomodulatory effects as well, but the molecular and immunological mechanisms of these actions are insufficiently investigated. This review focuses on the modulatory activity of DPP-4i in the immune system and the possible application of DPP-4i in other immune-related diseases in patients with or without diabetes.

Sitagliptin Induces Tolerogenic Human Dendritic Cells

Sitagliptin, an anti-diabetic drug, is a dipeptidyl peptidase (DPP)-4/CD26 inhibitor with additional anti-inflammatory and immunomodulatory properties. In this study, we investigated for the first time the effect of sitagliptin on the differentiation and functions of human dendritic cells generated from monocytes (MoDCs) for 4 days using the standard GM-CSF/IL-4 procedure. LPS/IFN-γ treatment for an additional 24 h was used for maturation induction of MoDCs. Sitagliptin was added at the highest non-cytotoxic concentration (500 µg/mL) either at the beginning (sita 0d protocol) or after MoDC differentiation (sita 4d protocol). Sitagliptin impaired differentiation and maturation of MoDCs as judged with the lower expression of CD40, CD83, CD86, NLRP3, and HLA-DR, retention of CD14 expression, and inhibited production of IL-β, IL-12p70, IL-23, and IL-27. In contrast, the expression of CD26, tolerogenic DC markers (ILT4 and IDO1), and production of immunoregulatory cytokines (IL-10 and TGF-β) were increased. Generally, the sita 0d protocol was more efficient. Sitagliptin-treated MoDCs were poorer allostimulators of T-cells in MoDC/T-cell co-culture and inhibited Th1 and Th17 but augmented Th2 and Treg responses. Tolerogenic properties of sitagliptin-treated MoDCs were additionally confirmed by an increased frequency of CD4+CD25+CD127- FoxP3+ Tregs and Tr1 cells (CD4+IL-10+FoxP3-) in MoDC/T-cell co-culture. The differentiation of IL-10+ and TGF-β+ Tregs depended on the sitagliptin protocol used. A Western blot analysis showed that sitagliptin inhibited p65 expression of NF-kB and p38MAPK during the maturation of MoDCs. In conclusion, sitagliptin induces differentiation of tolerogenic DCs, and the effect is important when considering sitagliptin for treating autoimmune diseases and allotransplant rejection.

Insights on the role of anti-inflammatory and immunosuppressive agents in the amelioration of diabetes

Diabetes is a major health problem worldwide. It is a chronic metabolic disorder that produces overt hyperglycemic condition that occurs either when the pancreas does not produce enough insulin due to excessive destruction of pancreatic β-cells (type 1 diabetes) or due to development of insulin resistance (type 2 diabetes). An autoimmune condition known as type 1 diabetes (T1D) results in the targeted immune death of β-cells that produce insulin. The only available treatment for T1D at the moment is the lifelong use of insulin. Multiple islet autoantibody positivity is used to diagnose T1D. There are four standard autoantibodies observed whose presence shows the development of T1D: antibodies against insulin, glutamic acid decarboxylase (GAD65), zinc T8 transporter (ZnT8), and tyrosine phosphatase-like protein (ICA512). In type 2 diabetes (T2D), an inflammatory response precipitates as a consequence of the immune response to high blood glucose level along with the presence of inflammation mediators produced by macrophages and adipocytes in fat tissue. The slow and chronic inflammatory condition of adipose tissue produces insulin resistance leading to increased stress on pancreatic β-cells to produce more insulin to compensate for the insulin resistance. Thus, this stress condition exacerbates the apoptosis of β-cells leading to insufficient production of insulin, resulting in hyperglycemia which signifies late stage T2D. Therefore, the therapeutic utilization of immunosuppressive agents may be a better alternative over the use of insulin and oral hypoglycemic agents for the treatment of T1D and T2D, respectively. This review enlightens the immune intervention for the prevention and amelioration of T1D and T2D in humans with main focus on the antigen-specific immune suppressive therapy.

Enhanced production of interleukin-29 and related genes are associated with T helper 1 cell parameters in patients with type 2 diabetes mellitus

OBJECTIVE

The production of interleukin (IL)-29 andthe genes related to IL-29 signaling pathway (STAT1, NF-κB, and NFATc1), and T helper (Th) 1 cells (T-bet, IFN-γ, TNF-α, and IL-2) were evaluated in type 2 diabetes mellitus (T2DM). Correlations between IL-29 and diabetes parameters, and between gene expression in IL-29 pathway and Th1 cells were also examined.

MATERIALS AND METHODS

41 newly diagnosed patients with T2DM and 41 healthy controls were recruited. CD4⁺ T cells were purifed and the production of IL-29 in the supernatant of anti- CD3 and anti- CD28 activated Th cells was detected using ELISA. The expression of IL-29- and Th1- related genes was determined with real-time PCR.

RESULTS

The secretion of IL-29 and the expression levels of NF-κB, NFATc1, IFN-γ, and TNF-α in Th cells were seen to be increased in diabetes persons compared to controls. Positive connections between IL-29 with hemoglobin A1c (HbA1c) and fasting plasma glucose (FPG) were found in diabetes persons. IL-29 was positively correlated with NFATc1 and TNF-α. NFATc1 was positively related to TNF-α.

CONCLUSION

Abnormal expression levels of IL-29- and Th1- related genes are linked with T2DM pathogenesis. IL-29 may amplify the expression of Th1-specific genes especially TNF-α by upregulating NFATc1 expression.

Impact of interleukin-32α on T helper cell-related cytokines, transcription factors, and proliferation in patients with type 2 diabetes mellitus

OBJECTIVE

The ability of interleukin (IL)-32α to induce T helper (Th) 1, Th17, and Treg cytokines (IFN-γ, IL-17, and IL-10, respectively), and transcription factors [(signal transducer and activator of transcription (STAT) 1 and T-box (T-bet) for Th1, STAT3 and retinoid-related orphan receptor (ROR)-γt for Th17, and STAT5 and forkhead box P3 (Foxp3) for Treg)] were investigated in type 2 diabetes mellitus (T2DM). IL-32α effects on Th cell proliferation and related factors including IL-2 and NF-κB were also explored.

METHODS

Serum levels of IL-32α in 31 patients and 31 healthy controls (HCs) were determined by ELISA assay. CD4⁺ T cells cultured with polyclonal activators in the presence and absence of recombinant IL-32α (rIL-32α). Gene expressions in cultured Th cells were assessed with real-time PCR. Cytokines in supernatants were measured with ELISA. Proliferation experiments were assessed by flow cytometry.

RESULTS

The patients showed significant increase in IL-32α levels compared with HCs and its levels were positively correlated with fasting plasma glucose and hemoglobin A1c. rIL-32α enhanced IL-17 and IL-2 production, increased ROR-γt and NF-κB expression, and enhanced Th proliferation in both patients and HCs. In patients, IL-17, ROR-γt, NF-κB, and proliferation levels were higher than those in HCs, in cultures with and without rIL-32α (rIL-32α⁺ and rIL-32α^-). IL-2 levels in rIL-32α⁺cultures of patients were significantly higher than the HCs, and it was positively correlated with proliferation rate and NF-κB expression.

CONCLUSIONS

Aberrant IL-32α levels are participated in T2DM pathogenesis. IL-32α potently induces Th17-related factors and amplifies the proliferative function of T cells.

The mechanisms of saffron (Crocus sativus') on the inflammatory pathways of diabetes mellitus: A systematic review

BACKGROUND

and amis: Diabetes is one of the major medical problems, which can lead to damage to cells or organs in various parts of the body. Saffron as herbal medicine has contained several active ingredients, including safranal, flavonoids, crocetin, and crocin, which are effective in modulating oxidative stress and inflammation, which can play the main role in reducing the effects of diabetes. However, so far, the effect of saffron on diabetes inflammation has not been evaluated in the form of systematic review studies. The purpose of this systematic study was to evaluate the evidence obtained from in-vitro, animal, and clinical trials studies on the effects of saffron on inflammation in diabetes.

METHODS

The present systematic review was conducted according to the guidelines of the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statements. In this systematic review, databases such as Embase, Pubmed, SCOPUS, ProQuest, and sciences direct database were searched from the beginning to February 2021. All eligible in-vitro, animal and human studies that examined the effect of saffron on inflammatory factors in diabetes were published in the form of a full article in English.

RESULTS

In the end, only 20 of the 596 articles met the criteria for analysis. Of the 20 articles, 3 were in-vitro studies, 13 were animal studies, and 4 were human studies.

CONCLUSION

The findings of this systematic study (Except for two studies) suggest that saffron supplementation with potential anti-inflammatory properties may reduce the expression of the inflammatory pathway and the production of inflammatory products in diabetes.

Nitazoxanide Exerts Immunomodulatory Effects on Peripheral Blood Mononuclear Cells from Type 2 Diabetes Patients

Background: Type 2 diabetes (T2D) is a low-grade inflammatory condition with abnormalities in the immune response mediated by T lymphocytes and macrophages. Drug repositioning for immunomodulatory molecules is an attractive proposal for treating T2D. Nitazoxanide (NTZ) is a broad-spectrum drug with promising immunomodulatory effects. Thus, we investigated the immunomodulatory effect of NTZ on peripheral blood mononuclear cells (PBMCs) from patients with T2D. Methods: Fifty patients with T2D were selected, and the proliferative response of T lymphocytes and the M1/M2 ratio of macrophages post cell culture were evaluated by flow cytometry, as well as measuring the concentration of cytokines by ELISA and the relative expression of microRNAs (miRNAs) related to the immune response by real-time PCR. Results: NTZ exerts an inhibitory effect on the cell proliferation of T lymphocytes stimulated with anti-CD3 and anti-CD28 antibodies without modifying cell viability, and significant decreases in the supernatant concentrations of interleukin (IL)-1β, IL-2, IL-6, IL-10, and IL-12. Furthermore, NTZ negatively regulates the relative expression of miR-155-5p without changes in miR-146a-5p. The M1/M2 ratio of monocytes/macrophages decreased the M1 and increased the M2 subpopulation by NTZ. Conclusions: Our results suggest that NTZ exerts immunomodulatory effects on PBMCs from T2D patients, and shows potential alternative therapeutic benefits.

Cytokine storm modulation in COVID-19: a proposed role for vitamin D and DPP-4 inhibitor combination therapy (VIDPP-4i)

A dysregulated immune response characterized by the hyperproduction of several pro-inflammatory cytokines (a.k.a. ‘cytokine storm’) plays a central role in the pathophysiology of severe coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this Perspective article we discuss the evidence for synergistic anti-inflammatory and immunomodulatory properties exerted by vitamin D and dipeptidyl peptidase-4 (DPP-4) inhibitors, the latter being a class of antihyperglycemic agents used for the treatment of Type 2 diabetes, which have also been reported as immunomodulators. Then, we provide the rationale for investigation of vitamin D and DPP-4 inhibitor combination therapy (VIDPP-4i) as an immunomodulation strategy to ratchet down the virulence of SARS-CoV-2, prevent disease progression and modulate the cytokine storm in COVID-19.

The so-called ‘cytokine storm’ that drives the hyperproduction of pro-inflammatory mediators, plays a central role in the pathophysiology of severe coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Vitamin D has increasingly been shown to play anti-inflammatory and immunomodulatory properties beyond its role in the regulation of bone homeostasis. Similarly, dipeptidyl peptidase-4 inhibitors (DPP-4i) – a class of antihyperglycemic agents used for the treatment of Type 2 diabetes – have been reported as immunomodulators regardless of their glucose-lowering properties. We, therefore, discuss the role of vitamin D and DPP-4 inhibitor combination therapy (VIDPP-4i) as a potential immunomodulation strategy to prevent the development and/or halt the progression of the COVID-19-induced cytokine storm, particularly in patients with diabetes and cardiovascular disease.

Vitamin D and DPP-4 inhibitors exert anti-inflammatory and immunomodulatory properties. Vitamin D and DPP-4 inhibitor combination therapy (VIDPP-4i) may represent a valid therapeutic approach to ratchet down the virulence of SARS-CoV-2 and modulate the cytokine storm in COVID-19.

Association of lower vitamin D levels with inflammation and leucocytes parameters in patients with and without diabetes mellitus undergoing coronary angiography

BACKGROUND

Diabetes mellitus has been associated with a chronic low-grade inflammation and a higher risk of cardiovascular and infectious disease, that could be prevented by the effects of vitamin D. We aimed at evaluating the impact of vitamin D levels on the biomarkers of acute-phase response, inflammation and glucose metabolism in a large cohort of diabetic patients with cardiovascular disease.

MATERIALS AND METHODS

Consecutive patients undergoing coronary angiography were included. Diabetes mellitus was defined as previous diagnosis, specific treatment administration (oral drug or insulin), fasting glycaemia >6.99 mmol/L or HbA1c >48 mmol/L. Glucose parameters, white blood cells, Neutrophil-to-Lymphocyte Ratio (NLR), Monocyte-to-Lymphocyte Ratio (MLR), C-reactive protein (CRP) and vitamin D were measured at admission. Vitamin D levels were measured by chemiluminescence immunoassay kit LIAISON® Vitamin D assay (Diasorin Inc).

RESULTS

We included 1472 diabetic patients and 2499 non-diabetic patients that were divided according to vitamin D tertiles. Among diabetic patients, lower levels of vitamin D were associated with female gender (P = .02), obesity (P = .004), active smoking and acute presentation (P < .001) and with a more atherogenic metabolic profile. The levels of white blood cells, leucocytes subfamilies, and inflammatory parameters significantly correlated with vitamin D levels in both patients with and without diabetes (diabetic: P = .012 for WBC, P = .004 for NLR and P < .001 for MLR and C-reactive protein, non-diabetic: P < .001 for WBC; NLR, MLR and C-reactive protein, respectively). Among diabetic patients, results were confirmed at multivariate analysis with no significant interaction according to glycaemic control.

CONCLUSION

The present study demonstrates that, among patients with cardiovascular disease, vitamin D deficiency is associated with metabolic dysregulation and with an elevation of cellular and humoural inflammatory parameters, especially among diabetics, although not being dependent from glycaemic control.

Changes in T helper cell-related factors in patients with type 2 diabetes mellitus after empagliflozin therapy

The immune factors related to T helper (Th) 1 (T-bet, STAT1, and IFN-γ), Th17 (ROR-γt, STAT3, and IL-17), and Treg (FOXP3, STAT5, and IL-10) cells, and SOCS1/3 and the proliferation of Th cells were investigated in type 2 diabetes mellitus patients before (baseline) and after empagliflozin therapy. A total of 56 patients on metformin and gliclazide were separated into two groups: Group 1 did not receive empagliflozin (EMPA^-) and the Group 2 received 10 mg/day of empagliflozin for 6 months (EMPA⁺). The expressions of T-bet, ROR-γt, FOXP3, STAT1/3/5 and SOCS1/3 were evaluated in CD4⁺ T cells with real-time PCR. The production of IFN-γ, IL-17, and IL-10 from CD4⁺ T cells was measured using ELISA. The proliferation of Th cells was assessed with flow cytometry. Six months of empagliflozin therapy significantly reduced the expression of ROR-γt and increased FOXP3 and STAT5 expression, compared to baseline. Production of IL-17 decreased after empagliflozin treatment, while IL-10 was enhanced in the EMPA⁺ group. Oral administration of empagliflozin or the addition of empagliflozin to the cell cultures diminished the proliferation of Th cells. Empagliflozin showed anti-inflammatory effects on Th cells by decreasing Th17-related factors, reducing proliferation capacity, and increasing Treg cell properties.

Combination of vitamin D and dipeptidyl peptidase-4 inhibitors (VIDPP-4i) as an immunomodulation therapy for autoimmune diabetes

Type 1 diabetes (T1D) and latent autoimmune diabetes in adults (LADA) represent the most common types of autoimmune diabetes and are characterized by different age of onset, degrees of immune-mediated destruction of pancreatic beta cells and rates of disease progression towards insulin dependence. Several immunotherapies aimed to counteract autoimmune responses against beta cells and preserve beta-cell function are currently being investigated, particularly in T1D. Preliminary findings suggest a potential role of combination therapy with vitamin D and dipeptidyl peptidase-4 (DPP-4) inhibitors (VIDPP-4i) in preserving beta-cell function in autoimmune diabetes. This manuscript aims to provide a comprehensive overview of the immunomodulatory properties of vitamin D and DPP-4 inhibitors, as well as the rationale for investigation of their combined use as an immunomodulation therapy for autoimmune diabetes.

Recreational Dance Practice Modulates Lymphocyte Profile and Function in Diabetic Women

This study aimed to investigate the impact of a 16-week dance-based aerobic exercise program on lymphocyte function in healthy and type 2 diabetes mellitus (T2DM) women. We enrolled 23 women: 11 with T2DM and 12 non-diabetic controls. Initially, we performed anthropometry and body composition measurements, afterwards, plasma levels of C-reactive protein, lipids, and glucose were determined. We used flow cytometry to measure the CD25 and CD28 expression in circulating lymphocytes, T-regulatory (Treg) cell percentage, lymphocyte proliferation, and cytokines released by cultured lymphocytes. The T2DM group had a lower proportion of CD28+ cells and a higher percentage of Treg lymphocytes and proliferative capacity at the baseline compared with the control group. After 16 weeks of the program, differences in lymphocytes between the T2DM and the control groups disappeared. The dance program promoted IL-10 increase in both groups. We found decreased IL-4, IL-2, and IL-6 secretion in lymphocytes from the control group and increased IL-17 secretion and IL-10/IL-17 ratio in the T2DM group after the program. The program promoted marked changes in lymphocytes in diabetic women, leading to a balance between the different profiles.

Evaluation of Interleukin-23 and JAKs/STATs/SOCSs/ROR-γt Expression in Type 2 Diabetes Mellitus Patients Treated With or Without Sitagliptin

The production of interleukin-23 (IL-23) and the expression levels of related genes were evaluated in type 2 diabetes mellitus patients. The correlations between them were also determined. Thirty patients without sitagliptin (sitagliptin negative; SN), 30 patients with sitagliptin (sitagliptin positive; SP), and 30 healthy controls (HCs) were recruited. The level of IL-23 in the supernatant of anti CD3-activated peripheral blood mononuclear cells (PBMCs) was assessed using enzyme-linked immunosorbent assay. The expressions of IL-23, JAK1/JAK2/TYK2, STAT1/STAT3, ROR-γt, and SOCS1/SOCS3 in PBMCs were evaluated by real-time polymerase chain reaction. The production of IL-23 and the expressions of IL-23, JAK2, STAT3, and ROR-γt were observed to be enhanced in SN patients versus HCs, while the levels were decreased in SP patients versus SN patients (P < 0.05). SOCS1 and SOCS3 expressions were lower in SN patients than HCs, and their expressions were elevated in SP patients versus SN patients (P < 0.05). In SN patients, positive correlations between the IL-23 with fasting plasma glucose and HbA1c were observed, and JAK2/STAT3/ROR-γt were positively correlated with IL-23. JAK2, STAT3, and ROR-γt were positively related to each other and were negatively related to SOCS3. Enhanced IL-23/JAK2/STAT3/ROR-γt and reduced SOCS1/SOCS3 were found in SN patients. Sitagliptin may regulate the IL-23 and related gene expression.

Sustaining Circulating Regulatory T Cell Subset Contributes to the Therapeutic Effect of Paroxetine on Mice With Diabetic Cardiomyopathy

BACKGROUND

G protein coupled receptor kinase 2 (GRK2) inhibitor, paroxetine, has been approved to ameliorate diabetic cardiomyopathy (DCM). GRK2 is also involved in regulating T cell functions; the potential modifications of paroxetine on the immune response to DCM is unclear.Methods and Results:DCM mouse was induced by high-fat diet (HFD) feeding. A remarkable reduction in the regulatory T (Treg) cell subset in DCM mouse was found by flow cytometry, with impaired cardiac function evaluated by echocardiography. The inhibited Treg differentiation was attributable to insulin chronic stimulation in a GRK2-PI3K-Akt signaling-dependent manner. The selective GRK2 inhibitor, paroxetine, rescued Treg differentiation in vitro and in vivo. Furthermore, heart function, as well as the activation of excitation-contraction coupling proteins such as phospholamban (PLB) and troponin I (TnI) was effectively promoted in paroxetine-treated DCM mice compared with vehicle-treated DCM mice. Blockade of FoxP3 expression sufficiently inhibited the proportion of Treg cells, abolished the protective effect of paroxetine on heart function as well as PLB and TnI activation in HFD-fed mice. Neither paroxetine nor carvedilol could effectively ameliorate the metabolic disorder of HFD mice.

CONCLUSIONS

The impaired systolic heart function of DCM mice was effectively improved by paroxetine therapy, partially through restoring the population of circulating Treg cells by targeting the GRK2-PI3K-Akt pathway.

Enhanced expression of TIGIT but not neuropilin-1 in patients with type 2 diabetes mellitus

BACKGROUND

The aggressive T helper cell responses and regulatory T (Treg) cells dysfunction exist in type 2 diabetes mellitus (T2DM). The co-inhibitory T cell immunoglobulin and ITIM-domain (TIGIT), neuropilin-1 (Nrp-1), and the co-stimulatory CD226 play a critical role in the inhibition or activation of immune responses. In this project, the expression of TIGIT, CD226, Nrp-1, and their ligands, CD155 and semaphorin 3A (Sema-3A) were investigated in T2DM.

METHODS

Peripheral blood mononuclear cells (PBMCs) were collected from 30 patients with T2DM, and 30 healthy controls (HCs). The frequencies of TIGIT and Nrp-1 on CD4⁺CD25^hi Treg cells, CD4⁺CD25^- responder T cells, total CD4⁺ T cells, and non-CD4⁺ cells were assessed using flow cytometry. The mRNA levels of TIGIT, CD226, Nrp-1, CD155, and Sema-3A were assessed by real-time PCR.

RESULTS

The percentage and MFI of TIGIT on CD4⁺CD25^hi T cells, CD4⁺CD25^- T cells, total CD4⁺ T cells, and non-CD4⁺ cells were higher in patients versus HCs (p < 0.05 for all). The mRNA level of TIGIT was increased in patients compared with HCs (p = 0.003). No differences were observed in the expression of CD226, CD155, Nrp-1, and Sema-3A between the groups.

CONCLUSIONS

The expression of TIGIT was enhanced in T2DM and the TIGIT axis could be considered as a new therapeutic purpose for the T2DM.