Dysregulation of circulating CD4+CXCR5+ T cells in type 2 diabetes mellitus

Identification and characterization of circulating and adipose tissue infiltrated CD20+T cells from subjects with obesity that undergo bariatric surgery

T cells play critical roles in adipose tissue (AT) inflammation. The role of CD20+T cell in AT dysfunction and their contributing to insulin resistance (IR) and type 2 diabetes progression, is not known. The aim was to characterize CD20+T cells in omental (OAT), subcutaneous (SAT) and peripheral blood (PB) from subjects with obesity (OB, n = 42), by flow cytometry. Eight subjects were evaluated before (T1) and 12 months post (T2) bariatric/metabolic surgery (BMS). PB from subjects without obesity (nOB, n = 12) was also collected. Higher percentage of CD20+T cells was observed in OAT, compared to PB or SAT, in OB-T1. CD20 expression by PB CD4+T cells was inversely correlated with adiposity markers, while follicular-like CD20+T cells were positively correlated with impaired glucose tolerance (increased HbA1c). Notably, among OB-T1, IR establishment was marked by a lower percentage and absolute number of PB CD20+T cells, compared nOB. Obesity was associated with higher percentage of activated CD20+T cells; however, OAT-infiltrated CD20+T cells from OB-T1 with diabetes displayed the lowest activation. CD20+T cells infiltrating OAT from OB-T1 displayed a phenotype towards IFN-γ-producing Th1 and Tc1 cells. After BMS, the percentage of PB CD4+CD20+T cells increased, with reduced Th1 and increased Th17 phenotype. Whereas in OAT the percentage of CD20+T cells with Th1/17 and Tc1/17 phenotypes increased. Interestingly, OAT from OB pre/post BMS maintained higher frequency of effector memory CD20+T cells. In conclusion, CD20+T cells may play a prominent role in obesity-related AT inflammation.

The Functions of SARS-CoV-2 Receptors in Diabetes-Related Severe COVID-19

Angiotensin-converting enzyme 2 (ACE2) is considered a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor of high importance, but due to its non-ubiquitous expression, studies of other proteins that may participate in virus internalisation have been undertaken. To date, many alternative receptors have been discovered. Their functioning may provide an explanation for some of the events observed in severe COVID-19 that cannot be directly explained by the model in which ACE2 constitutes the central point of infection. Diabetes mellitus type 2 (T2D) can induce severe COVID-19 development. Although many mechanisms associated with ACE2 can lead to increased SARS-CoV-2 virulence in diabetes, proteins such as basigin (CD147), glucose-regulated protein 78 kDa (GRP78), cluster of differentiation 4 (CD4), transferrin receptor (TfR), integrins α5β1/αvβ3, or ACE2 co-receptors neuropilin 2 (NRP2), vimentin, and even syalilated gangliosides may also be responsible for worsening the COVID-19 course. On the other hand, some others may play protective roles. Understanding how diabetes-associated mechanisms can induce severe COVID-19 via modification of virus receptor functioning needs further extensive studies.

Advances in Understanding of the Role of Immune Cell Phenotypes in Hypertension and Associated Vascular Disease

Many studies in the past 20 years have identified a contribution of inflammation and immune mechanisms to the pathophysiology of hypertension. Innate and adaptive immunity participate in this process. Among innate immune cells, macrophages and monocytes as well as dendritic cells, myeloid-derived suppressor cells, and neutrophils directly or via formation of neutrophil extracellular traps, play roles in the modulation of the inflammatory response in hypertension. Among adaptive immune cells, T and B cells have been implicated to varying degrees, particularly interleukin (IL)-17- and interferon γ-producing T lymphocytes, antagonized by T regulatory lymphocytes that are anti-inflammatory via production of IL-10. Among T cells that produce abundant IL-17, γδ T cells are unconventional T lymphocytes that are infrequent in the circulation in contrast to the much more abundant circulating αβ T lymphocytes, but are found mostly in tissues, and appear to play a role in triggering and sustaining inflammation in hypertension leading to vascular and renal injury. This review will provide an overview of these different immune cell phenotypes involved in the immune pathophysiology of hypertension and associated vascular disease.

Naturally acquired antibodies against 4 Streptococcus pneumoniae serotypes in Pakistani adults with type 2 diabetes mellitus

Immune response elicited during pneumococcal carriage has been shown to protect against subsequent colonization and infection by Streptococcus pneumoniae. The study was designed to measure the baseline serotype-specific anti-capsular IgG concentration and opsonic titers elicited in response to asymptomatic carriage in adults with and without type 2-diabetes. Level of IgG to capsular polysaccharide was measured in a total of 176 samples (124 with type 2 diabetes and 52 without type 2 diabetes) against serotype 1, 19F, 9V, and 18C. From within 176 samples, a nested cohort of 39 samples was selected for measuring the functional capacity of antibodies by measuring opsonic titer to serotypes 19F, 9V, and 18C. Next, we measured levels of IgG to PspA in 90 samples from individuals with and without diabetes (22 non-diabetes and 68 diabetes). Our results demonstrated comparable IgG titers against all serotypes between those with and without type 2-diabetes. Overall, we observed higher opsonic titers in those without diabetes as compared to individuals with diabetes for serotypes 19F and 9V. The opsonic titers for 19F and 9V significantly negatively correlated with HbA1c. For 19F, 41.66% (n = 10) showed opsonic titers ≥ 1:8 in the diabetes group as compared to 66.66% (n = 10) in the non-diabetes group. The percentage was 29.6% (n = 7) vs 66.66% (n = 10) for 9V and 70.83% (n = 17) vs 80% (n = 12) for 18C in diabetes and non-diabetes groups respectively. A comparable anti-PspA IgG (p = 0.409) was observed in those with and without diabetes, indicating that response to protein antigen is likely to remain intact in those with diabetes. In conclusion, we demonstrated comparable IgG titers to both capsular polysaccharide and protein antigens in those with and without diabetes, however, the protective capacity of antibodies differed between the two groups.

Changes of B cell subsets in different types of diabetes and its effect on the progression of latent autoimmune diabetes in adults

PURPOSE

Developmental abnormalities in B cells is one of the key players in autoimmune diabetes, but little is known about its role in latent autoimmune diabetes in adults (LADA). This study aimed to investigate the distribution of B cell subsets in different types of diabetes and to analyze their correlations with other biochemical parameters.

METHODS

A total of 140 participants were prospectively enrolled from January 2021 to December 2022. Diabetes-related autoantibodies and laboratory indicators were tested. Flow cytometry was used to analyze the percentage of circulating B cell subsets and T follicular cells. The correlation of B cell subsets with different indicators was assessed by Spearman's correlation method.

RESULTS

We observed that the Naïve phenotype cells tended to be less frequent in patients with diabetes than in healthy controls. The frequency of plasmablasts (PB) and Breg cell-related phenotype (B10) were significantly higher in LADA. Notably, the percentage of PB was positively associated with levels of islet cell antibody (ICA) and insulin autoantibody (IAA), but inversely associated with fasting C-peptide (FCP), further indicating that PB may promote the destruction of β-cell in patients with diabetes.

CONCLUSIONS

This study showed that patients with LADA had significantly altered frequencies of B cell subsets, particularly in the naïve to memory B cell ratio. Our study provided valuable information on the distribution characteristics of B cell subsets in LADA and suggested the feasibility of B-cell targeted therapy in LADA patients.

Elevated serum IL-2 and Th17/Treg imbalance are associated with gout

Gout is considered an auto-inflammatory disorder, and the immunological drivers have not been fully unraveled. This study compared the peripheral lymphocyte and CD4+T cell subsets, and cytokines in gout and healthy controls (HCs) to explore the contributions of T helper 17 (Th17) cells, T regulatory (Treg) cells and cytokines to the pathogenesis of gout. We enrolled 126 gout patients (53 early-onset gout with age of first presentation < 40 years, and 73 late-onset gout with age of first presentation ≥ 40 years) and 77 HCs. Percentage and absolute numbers of peripheral lymphocyte and CD4+T cell subpopulations in each group were detected by flow cytometry. The serum cytokine levels were determined by flow cytometric bead array. For circulating CD4+T cell subsets, Th17/Treg ratio was significantly higher in early-onset gout, late-onset gout and gout without tophus than HCs; Th17 cells were significantly elevated in early-onset gout and gout without tophus, while the percentage of Treg cells was significantly decreased in early-onset and late-onset gout. Additionally, gout patients had significantly higher cytokines levels (including IL-2, IL-4, IL-6, IL-10, IL-17, IFN-γ, and TNF-α) than HCs; IL-2 levels were positively correlated with Treg cells and negatively correlated with ESR. ROC analysis showed that disease duration, CRP and fibrinogen, had moderate predictive performances for tophus in gout (the AUCs were 0.753, 0.703 and 0.701, respectively). Our study suggests that early-onset and late-onset gout differ in Th17/Treg imbalance, which in early-onset gout is due to elevated Th17 cells and in late-onset gout is due to decreased Treg cells. And increased serum cytokine levels, especially IL-2, may play an essential role in that. Restoring Th17/Treg balance may be a crucial way to improve the prognosis of gout patients.

Wounds under diabetic milieu: The role of immune cellar components and signaling pathways

A major challenge in the field of diabetic wound healing is to confirm the body's intrinsic mechanism that could sense the immune system damage promptly and protect the wound from non-healing. Accumulating literature indicates that macrophage, a contributor to prolonged inflammation occurring at the wound site, might play such a role in hindering wound healing. Likewise, other immune cell dysfunctions, such as persistent neutrophils and T cell infection, may also lead to persistent oxidative stress and inflammatory reaction during diabetic wound healing. In this article, we discuss recent advances in the immune cellular components in wounds under the diabetic milieu, and the role of key signaling mechanisms that compromise the function of immune cells leading to persistent wound non-healing.

A nine-hub-gene signature of metabolic syndrome identified using machine learning algorithms and integrated bioinformatics

Early risk assessments and interventions for metabolic syndrome (MetS) are limited because of a lack of effective biomarkers. In the present study, several candidate genes were selected as a blood-based transcriptomic signature for MetS. We collected so far the largest MetS-associated peripheral blood high-throughput transcriptomics data and put forward a novel feature selection strategy by combining weighted gene co-expression network analysis, protein-protein interaction network analysis, LASSO regression and random forest approaches. Two gene modules and 51 hub genes as well as a 9-hub-gene signature associated with metabolic syndrome were identified. Then, based on this 9-hub-gene signature, we performed logistic analysis and subsequently established a web nomogram calculator for metabolic syndrome risk (https://xjtulgz.shinyapps.io/DynNomapp/). This 9-hub-gene signature showed excellent classification and calibration performance (AUC = 0.968 in training set, AUC = 0.883 in internal validation set, AUC = 0.861 in external validation set) as well as ideal potential clinical benefit.

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.

The Alterations in and the Role of the Th17/Treg Balance in Metabolic Diseases

Chronic inflammation plays an important role in the development of metabolic diseases. These include obesity, type 2 diabetes mellitus, and metabolic dysfunction-associated fatty liver disease. The proinflammatory environment maintained by the innate immunity, including macrophages and related cytokines, can be influenced by adaptive immunity. The function of T helper 17 (Th17) and regulatory T (Treg) cells in this process has attracted attention. The Th17/Treg balance is regulated by inflammatory cytokines and various metabolic factors, including those associated with cellular energy metabolism. The possible underlying mechanisms include metabolism-related signaling pathways and epigenetic regulation. Several studies conducted on human and animal models have shown marked differences in and the important roles of Th17/Treg in chronic inflammation associated with obesity and metabolic diseases. Moreover, Th17/Treg seems to be a bridge linking the gut microbiota to host metabolic disorders. In this review, we have provided an overview of the alterations in and the functions of the Th17/Treg balance in metabolic diseases and its role in regulating immune response-related glucose and lipid metabolism.

Frequency of Efficient Circulating Follicular Helper T Cells Correlates with Dyslipidemia and WBC Count in Atherosclerosis

Background

The significance of cTfh cells and their subsets in atherosclerosis is not well understood. We measured the frequency of cTfh subsets in patients with different degrees of stenosis using flow-cytometry.

Methods

Participants included high (≥50%; n = 12) and low (<50%; n = 12) stenosis groups, as well as healthy controls (n = 6).

Results

The frequency of CCR7loPD-1hiefficient-cTfh was significantly higher in patients with high stenosis compared to healthy controls (p = 0.003) and correlated with low-density lipoprotein (LDL; p = 0.043), cholesterol (p = 0.043), triglyceride (p = 0.019), neutrophil count (p = 0.032), platelet count (p = 0.024), neutrophil/lymphocyte ratio (NLR; p = 0.046), and platelet/lymphocyte ratio (PLR; p = 0.025) in high stenosis group. The frequency of CCR7hiPD-1lo quiescent-cTfh was higher in healthy controls compared to the high-stenosis group (p = 0.001) and positively correlated with high-density lipoprotein (p = 0.046). The frequency of efficient-cTfh cells was correlated with platelet count (p = 0.043), NLR (p = 0.036), and PLR (p P = 0.035) in low-stenosis group, while that of quiescent-cTfh cells was negatively correlated with LDL (p = 0.034), cholesterol (p = 0.047), platelet count (p = 0.032), and PLR (p = 0.041).

Conclusion

High percentages of cTfh and efficient-cTfh cells in patients with advanced atherosclerosis and their correlation with dyslipidemia and white blood cell counts suggest an ongoing cTfh subset deviation, towards efficient phenotype in the milieu of inflammation and altered lipid profile. Efficient cTfh cells have an effector phenotype and could in turn contribute to atherosclerosis progression.

The frequency of Tim-3 on circulating Tfh cells was increased in type 2 diabetes mellitus patients

Type 2 diabetes mellitus (T2DM) is a chronic, low-grade inflammation disease. T follicular helper (Tfh) cells and T cell immunoglobulin and mucin domain 3 (Tim-3) are implicated in many immune diseases. This study aims to explore whether Tim-3 expression on Tfh cells is associated with T2DM progression. White blood cells (WBCs) were harvested from 30 patients with T2DM and 20 healthy donors. The abundance of circulating Tfh cells (cTfh) and the frequency of Tim-3 were analyzed by flow cytometry. Levels of fasting plasma glucose (FPG), insulin, hemoglobin A1C (HbA1C), and fasting plasma C-peptide were measured. Body mass index (BMI) and diabetes duration were also recorded. Patients with T2DM had higher numbers of cTfh cells. In addition, cTfh cells showed a negative correlation with HbA1C and diabetes duration, a positive correlation with fasting plasma C-peptide. The frequency of Tim-3 on cTfh cells was higher among T2DM patients compared with healthy donors. The in vitro experiment showed that high glucose levels increased the abundance cTfh cells but had no effect on Tim-3 expression. Our results suggest that cTfh cells and associated Tim-3 frequency may contribute to the progression of T2DM, and high glucose levels may influence cTfh cells directly.

Unlike PD-L1, PD-1 Is Downregulated on Partial Immune Cells in Type 2 Diabetes

INTRODUCTION

Type 2 diabetes is a worldwide disease which is associated with chronic, low-grade inflammation. The PD-1/PD-L1 pathway has been reported to be a negative regulatory element in immune homeostasis and to be involved in many diseases.

MATERIALS AND METHODS

Peripheral blood mononuclear cells (PBMCs) were obtained from type 2 diabetes patients (n = 23) and healthy donors (n = 20). The PD-L1 and PD-1 expressions on corresponding immune cells were evaluated by flow cytometry.

RESULTS

The PD-L1 expression on corresponding immune cells has no significant difference between these two groups. We showed the downregulated PD-1 expression in type 2 diabetes patients. The correlation analysis indicated that the PD-1 on NK cells has a positive correlation with insulin and diabetes duration. And an inverse correlation has been shown between the PD-1 expression on monocytes and BMI (body mass index).

CONCLUSIONS

The results in this article suggest that PD-1, unlike PD-L1, might participate in the progression of type 2 diabetes. This investigation will provide evidence for the potential immune therapy for T2D.

Integrative analysis of super enhancer SNPs for type 2 diabetes

Clinical studies in type 2 diabetes (T2D) primarily focused on the single nucleotide polymorphisms (SNPs) located in protein-coding regions. Recently, the SNPs located in noncoding regions have also been recognized to play an important role in disease susceptibility. The super enhancer is a cluster of transcriptional enhancers located in noncoding regions. It plays a critical role in cell-type specific gene expression. However, the exact mechanism of the super enhancer SNPs for T2D remains unclear. In this study, we integrated genome-wide association studies (GWASs) and T2D cell/tissue-specific histone modification ChIP-seq data to identify T2D-associated SNPs in super enhancer, followed by comprehensive bioinformatics analyses to further explore the functional importance of these SNPs. We identified several interesting T2D super enhancer SNPs. Interesting, most of them were clustered within the same or neighboring super enhancers. A number of SNPs are involved in chromatin interactive regulation and/or potentially influence the binding affinity of transcription factors. Gene Ontology (GO) analysis showed a significant enrichment in several well-known signaling pathways and regulatory process, e.g. WNT signaling pathway, which plays a key role in T2D metabolism. Our results highlighted the potential functional importance of T2D super enhancer SNPs, which may yield novel insights into the pathogenesis of T2D.

Dysregulation of Circulating Tfr/Tfh Ratio in Primary biliary cholangitis

Follicular helper T (Tfh) cells and follicular regulatory T (Tfr) cells are critical for the development and maintenance of germinal centre (GC) and humoral immune responses. Accumulating evidence has demonstrated that the dysregulation of either Tfh cells or Tfr cells contributes to the pathogenesis of autoimmune diseases. We aim to investigate the roles of circulating Tfh cells and circulating Tfr cells in the pathogenesis of primary biliary cholangitis (PBC). A total of 34 patients with PBC and 27 health individuals were enrolled in this study. Flow cytometry revealed that circulating Tfh (CD4⁺ CXCR5⁺ CD127^hi CD25^lo ) cells were increased, but Tfr (CD4⁺ CXCR5⁺ CD127^lo CD25^hi ) cells and ratio of Tfr/Tfh were dramatically decreased in PBC patients compared with healthy controls. The Tfr/Tfh ratio was negatively correlated with level of serum IgM. Meanwhile, we also observed effector memory (CCR7^lo PD-1^hi ) Tfh cells and Tfr cells were dramatically increased, but central memory (CCR7^hi PD-1^lo ) Tfh cells and Tfr cells were decreased in PBC patients compared with healthy controls. Effector memory Tfr cells were positively correlated with level of serum ALP. These results indicate that an imbalance of circulating Tfr cells and Tfh cells may be involved in the immunopathogenesis of PBC and may provide novel insight for the development of PBC therapies.

Publication trends of research on diabetes mellitus and T cells (1997-2016): A 20-year bibliometric study

Introduction

Diabetes Mellitus (DM) is a huge burden for human health. Recent studies show the close relationship between DM and T cells. We investigated the trend in DM and T cells research.

Methods

Using the Web of Science database, we searched the publications on DM and T cells in 1997–2016, and studied the source data using bibliometric methodology. Excel 2016, GraphPad Prism 5, and VOSviewer software were used to analyze the publication trend in DM and T cells research.

Results

We found a total of 1077 publications with 38109 citations up to January 23, 2017. The highest contribution came from the United States, with 48.38% of the publications, 61.44% of the citations and the highest H-index (74). China had the 5th place for total publications, but ranked 11th both for citation frequency (604) and H-index (13). The inflection point of the global DM and T cells publications was in 2000. Journal of Immunology published the most related articles (164). Santamaria P. was the leading scholar in this field with the most publications (35). The keywords “regulatory T cell” and “autoimmune diabetes” were mentioned more than 300 times. Furthermore, type 2 (T2)DM, T cell immunoglobulin and mucin domain (TIM) and obesity are becoming popular research topics in this field.

Conclusion

The quantity of publications on DM and T cells grew rapidly around year 2000, but has relatively decreased recently. The United States had the leading position in global research. There was a discrepancy between productivity and quality of publications from China. Latest progress is most likely first published by the Journal of Immunology. Santamaria P., Roep B.O. and Peakman M. were the pioneer scholars in this field. Most researchers have focused on “regulatory T cell” and “autoimmune diabetes” research. In future, T2DM, TIM and obesity may be the popular areas.

Relationship between different subpopulations of circulating CD4+ T lymphocytes and microvascular or systemic oxidative stress in humans

BACKGROUND AND OBJECTIVE

Different components of the immune system, including innate and adaptive immunity (T effector lymphocytes and T regulatory lymphocytes - TREGs) may be involved in the development of hypertension, vascular injury and inflammation. However, no data are presently available in humans about possible relationships between T-lymphocyte subtypes and microvascular oxidative stress. Our objective was to investigate possible relationships between T-lymphocyte subtypes and systemic and microvascular oxidative stress in a population of normotensive subjects and hypertensive patients.

PATIENTS AND METHODS

In the present study we enrolled 24 normotensive subjects and 12 hypertensive patients undergoing an elective surgical intervention. No sign of local or systemic inflammation was present. All patients underwent a biopsy of subcutaneous fat during surgery. A peripheral blood sample was obtained before surgery for assessment of T lymphocyte subpopulations by flow cytometry and circulating indices of oxidative stress.

RESULTS

A significant direct correlation was observed between Th1 lymphocytes and reactive oxygen species (ROS) production (mainly in microvessels). Additionally, significant inverse correlations were observed between ROS and total TREGs, or TREGs subtypes. Significant correlations were detected between circulating indices of oxidative stress/inflammation and indices of microvascular morphology/Th1 and Th17 lymphocytes. In addition, a significant inverse correlation was detected between TREGs in subcutaneous small vessels and C reactive protein.

CONCLUSIONS

Our data suggest that TREG lymphocytes may be protective against microvascular damage, probably because of their anti-oxidant properties, while Th1-Th17 lymphocytes seem to exert an opposite effect, confirming an involvement of adaptive immune system in microvascular damage.

Relationship Between Different Subpopulations of Circulating CD4+ T-lymphocytes and Microvascular Structural Alterations in Humans

BACKGROUND

Different components of the immune system, including innate and adaptive immunity (T-effector lymphocytes and T-regulatory lymphocytes-TREGs) may be involved in the development of hypertension. In addition, it was demonstrated in animal models that TREGs may prevent angiotensin II-induced hypertension and vascular injury/inflammation. However, no data are presently available in humans about possible relationships between T-lymphocyte subtypes and microvascular structural alterations.

METHODS

For this purpose, in the present study, we enrolled 24 normotensive subjects and 12 hypertensive patients undergoing an elective surgical intervention. No sign of local or systemic inflammation was present. All patients underwent a biopsy of subcutaneous fat during surgery. Subcutaneous small resistance arteries were dissected and mounted on a wire myograph and the media to lumen ratio (M/L) was calculated. In addition, retinal arteriolar structure was evaluated noninvasively by scanning laser Doppler flowmetry. Capillary density in the nailfold, dorsum of the finger, and forearm were evaluated by videomicroscopy. A peripheral blood sample was obtained before surgery for assessment of T-lymphocyte subpopulations by flow cytometry.

RESULTS

Significant negative correlations were observed between indices of microvascular structure (M/L of subcutaneous small arteries and wall to lumen ratio of retinal arterioles) and circulating TREG lymphocytes. A direct correlation was observed between M/L of subcutaneous small arteries and circulating Th17 lymphocytes. In addition, total capillary density was correlated with a TREG effector memory subpopulation.

CONCLUSION

Our data suggest that some lymphocyte subpopulations may be related to microvascular remodeling, confirming previous animal data, and opening therapeutic possibilities.

Autoantibodies against β1-adrenoceptor induce blood glucose enhancement and insulin insufficient via T lymphocytes

Diabetes mellitus is a chronic metabolic disorder with a high morbidity and mortality, but its pathogenesis is not fully understood. An increasing amount of evidence indicates that an immune mechanism plays an important role in the pathogenesis of diabetes. We demonstrated previously that the long-term presence of autoantibodies against the second extracellular loop of the β₁-adrenoceptor (β₁-AA) could change the ratio of peripheral CD4+T/CD8+T in rats, which was accompanied by lymphocytes infiltration in the rat heart, liver, and kidneys. To investigate whether β₁-AA is involved in the pathogenesis of diabetes, BALB/c or nude mice were passively immunized with monoclonal antibodies against β₁-AR (β₁-AR mAb). Compared with vehicle control mice, β₁-AA-positive BALB/c mice exhibited significantly increased blood glucose (P < 0.01) and increased fasting insulin (P < 0.05). However, the same changes did not occur in the nude mice. And altered islet morphology was found at week 28 in β₁-AA immunization group compared with vehicle control. The basal insulin level of NIT-1 β-cells was decreased markedly (P < 0.01), and the lactate dehydrogenase level was increased (P < 0.01) after the administration of conditioned media from T lymphocytes that had been treated with β₁-AA alone. However, these effects were reversed by treatment with metoprolol or peptides of the second extracellular loop of β₁-adrenoceptor (β₁-AR-EC_II). These results suggest that β₁-AA could induce hyperglycemia in both rats and mice, and also impair insulin secretion and change islet structure. T lymphocytes may play a key role in the pathogenesis of these changes in the islets.

Regulators of Tfh Cell Differentiation

The follicular helper T (Tfh) cells help is critical for activation of B cells, antibody class switching, and germinal center (GC) formation. The Tfh cells are characterized by the expression of CXC chemokine receptor 5 (CXCR5), ICOS, programed death 1 (PD-1), B cell lymphoma 6 (BCL-6), and IL-21. They are involved in clearing infections and are adversely linked with autoimmune diseases and also have a role in viral replication as well as clearance. On the one hand, Tfh cells are generated from naive CD4⁺ T cells with sequential steps involving cytokine signaling (IL-21, IL-6, IL-12, activin A), migration, and positioning in the GC by CXCR5, surface receptors (ICOS/ICOSL, signaling lymphocyte activation molecule-associated protein/signaling lymphocyte activation molecule) as well as transcription factor (BCL-6, c-Maf, and signal transducer and activator of transcription 3) signaling and repressor miR155. On the other hand, Tfh generation is negatively regulated at specific steps of Tfh generation by specific cytokine (IL-2, IL-7), surface receptor (PD-1, CTLA-4), transcription factors B lymphocyte maturation protein 1, signal transducer and activator of transcription 5, T-bet, KLF-2 signaling, and repressor miR 146a. Interestingly, miR-17-92 and FOXO1 act as a positive as well as a negative regulator of Tfh differentiation depending on the time of expression and disease specificity. Tfh cells are also generated from the conversion of other effector T cells as exemplified by Th1 cells converting into Tfh during viral infection. The mechanistic details of effector T cells conversion into Tfh are yet to be clear. To manipulate Tfh cells for therapeutic implication and or for effective vaccination strategies, it is important to know positive and negative regulators of Tfh generation. Hence, in this review, we have highlighted and interlinked molecular signaling from cytokines, surface receptors, transcription factors, ubiquitin ligase, and microRNA as positive and negative regulators for Tfh differentiation.

T cell immunoglobulin and mucin domain-containing molecule 3 on CD14+ monocytes serves as a novel biological marker for diabetes duration in type 2 diabetes mellitus

Aims/Introduction

Type 2 diabetes is a worldwide disease that is associated with increased rates of obesity and reduced physical activity. Obesity‐associated insulin resistance in type 2 diabetes is a disorder in the balance between pro‐inflammatory and anti‐inflammatory signals. T cell immunoglobulin and mucin domain‐containing molecule 3 (Tim‐3) has been reported as an important regulatory inflammation molecule, and plays a pivotal role in several inflammation‐related diseases.

Materials and Methods

Peripheral blood mononuclear cells were obtained from type 2 diabetes patients (n = 31) and healthy donors (n = 18), and Tim‐3 expression on peripheral blood mononuclear cells was evaluated by flow cytometry.

Results

We showed the downregulated expression of Tim‐3 on CD14⁺ monocytes from type 2 diabetes patients. In addition, the upregulated expression of Tim‐3 on peripheral CD4⁺ T cells and CD8⁺ T cells was observed in the present study. The correlation analysis between Tim‐3 expression on CD14⁺ monocytes and diabetes duration showed the longer diabetes duration time, the lower Tim‐3 expression on CD14 monocytes.

Conclusions

The present results suggest that Tim‐3 might participate in the progression of type 2 diabetes by its negative regulation on these immune cells, and Tim‐3 on CD14⁺ monocytes serves as a novel biological marker for diabetes duration in type 2 diabetes patients.

Adaptive Immunity and Antigen-Specific Activation in Obesity-Associated Insulin Resistance

Type 2 diabetes mellitus (T2D) is a metabolic disease that is strongly tied to obesity and often preceded by insulin resistance (IR). It has been established that chronic inflammation of hypertrophic adipose tissue depots in obese individuals leads to obesity-associated IR and is mediated by cells of the innate immune system, particularly macrophages. More recently, cells of the adaptive immune system, B and T lymphocytes, have also emerged as important regulators of glucose homeostasis, raising the intriguing possibility that antigen-driven immune responses play a role in disease. In this review, we critically evaluate the roles that various B and T cell subsets play in IR, and then we examine the data suggesting that antigen-driven mechanisms, such as antigen presentation and costimulation, may drive the activity of these lymphocytes.