Elevated proinflammatory cytokine production by a skewed T cell compartment requires monocytes and promotes inflammation in type 2 diabetes

Interplay Between Insulin Resistance and Immune Dysregulation in Type 2 Diabetes Mellitus: Implications for Therapeutic Interventions

Type 2 Diabetes Mellitus (T2DM) is a rapidly growing global health issue characterized by insulin resistance and chronic inflammation. Beyond regulating glucose homeostasis, insulin plays a pivotal role in modulating immune cell function, linking metabolic dysregulation with immune responses. This review examines the intricate relationship between insulin resistance and immune dysfunction in T2DM, focusing on how impaired insulin signaling pathways, particularly PI3K/Akt and MAPK, contribute to immune cell activation, proliferation, and chronic inflammation. Insulin resistance impacts immune cells such as T cells, B cells, macrophages, and neutrophils, leading to an imbalance between pro-inflammatory and anti-inflammatory responses. Elevated pro-inflammatory cytokines (eg, TNF-α, IL-6) and adipokines (eg, leptin, resistin) exacerbate insulin resistance, promoting a vicious cycle of metabolic and immune dysregulation. This interplay contributes to the chronic low-grade inflammation that underlies T2DM pathogenesis, further impairing insulin signaling and glucose metabolism. Restoration of insulin sensitivity is, therefore, a critical step toward correcting immune imbalance in insulin-resistant states like T2DM. Therapeutic approaches that reduce inflammation could also support improvements in insulin sensitivity, addressing both metabolic and immune disturbances simultaneously. The review also explores therapeutic strategies, including insulin therapy, targeting insulin signaling pathways, and lifestyle interventions. Insulin therapy can reduce pro-inflammatory cytokine production and enhance anti-inflammatory responses, although challenges such as potential immune suppression and hyperinsulinemia remain. Targeting key signaling pathways and transcription factors offers promising avenues for modulating immune responses, while lifestyle interventions, such as dietary modifications, physical activity, and weight management, can improve insulin sensitivity and reduce inflammation. By understanding the dual role of insulin in regulating both metabolic and immune functions, this review underscores the importance of addressing immune dysfunction as part of comprehensive T2DM management. Targeting the interconnected pathways of insulin signaling and immune regulation could lead to more effective therapeutic approaches, ultimately improving patient outcomes and reducing disease complications.

Diabetes can impact cellular immunity in solid tumors

Cancer is increasingly prevalent worldwide, often coexisting with type 2 diabetes (T2D). Recent breakthroughs reveal the immune system's pivotal role in eliminating tumors and how the metabolic environment, such as glucose availability, affects antitumor immunity. Diabetes is known to dysregulate both innate and adaptive immune responses, while cancer creates an immunosuppressive microenvironment. We hypothesize that diabetes in cancer subjects may exacerbate this immunosuppression. Here, we examine the current understanding of the interplay between T2D and solid tumors and the associated challenges. Despite inconsistencies in data from mouse models and human tissues, evidence suggests that T2D can impact the antitumor response. Possible mechanisms may involve myeloid cells, inducing local immunosuppression and impairing antigen presentation, and certain lymphoid cell populations, exhibiting exhaustion.

The Role of Th17/Treg Axis in Retinal Pathology Associated with Diabetes and Treatment Options

Diabetic retinopathy (DR) is a major complication of diabetes, leading to vision impairment and blindness. The pathogenesis of DR involves multiple factors, including hyperglycemia-induced vascular damage, hypertension, obesity, anemia, immune dysregulation, and disruption of the blood-retinal barrier (BRB). Th17 and Treg cells, two types of CD4+ T cells, play opposing roles in inflammation. Th17 cells are pro-inflammatory, producing cytokines such as IL-17A, while Treg cells help suppress immune responses and promote anti-inflammatory effects. Recent studies highlight the importance of the Th17/Treg balance in retinal inflammation and disease progression in DR. Our literature review reveals an imbalance in DR, with increased Th17 activity and reduced Treg function. This shift creates a pro-inflammatory environment in the retina, worsening vascular leakage, neovascularization, and vision loss. The limited infiltration of Treg cells suggests that Th17 cells may uniquely infiltrate the retina by overwhelming or outnumbering Tregs or increasing the expression of recruiting chemokines, rather than only taking advantage of a damaged BRB. Therapeutic strategies, such as neutralizing IL-17A and enhancing Treg function with compounds like IL-35 or curcumin, may reduce inflammation and retinal damage. Restoring the balance between Th17 and Treg cells could provide new approaches for treating DR by controlling inflammation and preventing further retinal damage.

The adaptive immune system in the retina of diabetics

As the prevalence of diabetes mellitus increases each year, its most common microvascular complication, diabetic retinopathy (DR), is also on the rise. DR is now regarded as an inflammatory disease in which innate immunity plays a crucial role, and a large number of innate immune cells with associated cytokines are involved in the pathologic process of DR. The role of adaptive immunity in DR is seldom mentioned, probably due to the general perception of the immune privileged environment of the retina; however, in recent years there has been a gradual increase in research on the role of adaptive immunity in DR, and with the discovery of the retinal lymphatic system, it seems that the role of adaptive immunity can no longer be ignored. Here, we discuss the immunosuppressive environment of the retina, the phenomenon and potential mechanisms of lymphocyte infiltration in DR, and the role of the adaptive immune system in the diabetic retina, which may point the way for future research.

San Huang Xiao Yan recipe promoted wound healing in diabetic ulcer mice by inhibiting Th17 cell differentiation

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetic ulcer is a serious diabetes complication and a primary reason for amputations. For many years, the San Huang Xiao Yan (SHXY) recipe has served as a conventional remedy for these ulcers, effectively reducing inflammatory factors and exhibiting considerable therapeutic efficacy. However, the precise mechanism remains incompletely understood.

AIM OF THE STUDY

To explore the efficacy and mechanisms of SHXY and its active ingredients in treating diabetic ulcer.

MATERIALS AND METHODS

A diabetic ulcer mouse model was established using C57BL/6J mice on a high-fat diet, followed by streptozotocin injection and skin damage. We investigated the bioactive compounds, key targets, and pharmacological mechanisms of SHXY in addressing diabetic ulcers through network pharmacology, molecular docking, both in vitro and in vivo validation experiments.

RESULTS

One week after intragastric administration, SHXY can reduce inflammation and edema, increase collagen synthesis, and reduce the expression of RORγT and IL-17A without affecting Treg cells. In vitro, SHXY-containing serum inhibited the differentiation of Th17 cells but did not affect Treg and Th1 cells. Network pharmacology found that SHXY acts through inflammatory pathways, including TNF, IL-17, Th17 cell differentiation, HIF-1, and PI3K-Akt.

CONCLUSIONS

SHXY and its candidate enhance healing in diabetic ulcers by modulating CD4+ T cells, particularly by inhibiting Th17 cell differentiation.

An in-depth understanding of the role and mechanisms of T cells in immune organ aging and age-related diseases

T cells play a critical and irreplaceable role in maintaining overall health. However, their functions undergo alterations as individuals age. It is of utmost importance to comprehend the specific characteristics of T-cell aging, as this knowledge is crucial for gaining deeper insights into the pathogenesis of aging-related diseases and developing effective therapeutic strategies. In this review, we have thoroughly examined the existing studies on the characteristics of immune organ aging. Furthermore, we elucidated the changes and potential mechanisms that occur in T cells during the aging process. Additionally, we have discussed the latest research advancements pertaining to T-cell aging-related diseases. These findings provide a fresh perspective for the study of T cells in the context of aging.

Lymphocyte Subset Imbalance in Cardiometabolic Diseases: Are T Cells the Missing Link?

Cardiometabolic and cardiovascular diseases (CVDs) remain the leading cause of death worldwide, with well-established risk factors such as smoking, obesity, and diabetes contributing to plaque formation and chronic inflammation. However, emerging evidence suggests that the immune system plays a more significant role in the development and progression of CVD than previously thought. Specifically, the finely tuned regulation of lymphocyte subsets governs post-injury inflammation and tissue damage resolution and orchestrates the functions and activation of endothelial cells, cardiomyocytes, and fibroblasts in CVD-associated lesions (e.g., atherosclerotic plaques). A deeper understanding of the immune system's involvement in CVD development and progression will provide new insights into disease biology and uncover novel therapeutic targets aimed at re-establishing immune homeostasis. In this review, we summarize the current state of knowledge on the distribution and involvement of lymphocyte subsets in CVD, including atherosclerosis, diabetes, hypertension, myocardial infarction, and stroke.

Assessing the effects of diabetes mellitus on the monocyte-to-lymphocyte ratio and the QuantiFERON-TB gold plus assays for tuberculosis treatment monitoring: a prospective cohort study

Diabetes mellitus (DM) is an important risk factor for the development of active tuberculosis (TB). QuantiFERON-TB Gold Plus (QFT-P), white blood cell count (WBC) assays and monocyte-to-lymphocyte ratio (MLR) reflect the inflammatory reactions associated with TB and offer the potential to monitor TB treatment to allow a better management of the disease. The aim of this study was to assess the influence of DM on the respective performances of QFT-P and WBC assays in their capacities to monitor the treatment of drug-sensitive pulmonary TB (TBP). The QFT-P and WBC were prospectively compared between TB patients with and without DM at inclusion (D0), at the end of treatment (M6) and two months after the end of treatment (M8). After laboratory measurement of glycated hemoglobin (HbA1c), the patients were categorized into two groups: the TBP (n=43) and the TBDM (n=30) groups. The TBDM patients were characterized by an elevated Mycobacterium tuberculosis-specific QFT-P IFN-γ response after TB treatment compared to the TBP group (p<0.001 and p<0.05, respectively, after TB1 and TB2 antigens stimulation). A significantly higher proportion of positive QFT-P tests was observed in the TBDM group compared to the TBP group (91.3% vs 64.1%) at the end of the treatment (p=0.03). MLR analysis showed a decrease of MLR value after TB treatment for both diabetic and nondiabetic TB patients (p<0.001 and p<0.05). These data reflected from immune-host based tests used to monitor the TB treatment, seemed to further suggest that TB with concomitant DM is associated with a persistent inflammatory response after TB treatment.

Immunometabolic alterations in type 2 diabetes mellitus revealed by single-cell RNA sequencing: insights into subtypes and therapeutic targets

Background

Type 2 Diabetes Mellitus (T2DM) represents a major global health challenge, marked by chronic hyperglycemia, insulin resistance, and immune system dysfunction. Immune cells, including T cells and monocytes, play a pivotal role in driving systemic inflammation in T2DM; however, the underlying single-cell mechanisms remain inadequately defined.

Methods

Single-cell RNA sequencing of peripheral blood mononuclear cells (PBMCs) from 37 patients with T2DM and 11 healthy controls (HC) was conducted. Immune cell types were identified through clustering analysis, followed by differential expression and pathway analysis. Metabolic heterogeneity within T cell subpopulations was evaluated using Gene Set Variation Analysis (GSVA). Machine learning models were constructed to classify T2DM subtypes based on metabolic signatures, and T-cell-monocyte interactions were explored to assess immune crosstalk. Transcription factor (TF) activity was analyzed, and drug enrichment analysis was performed to identify potential therapeutic targets.

Results

In patients with T2DM, a marked increase in monocytes and a decrease in CD4+ T cells were observed, indicating immune dysregulation. Significant metabolic diversity within T cell subpopulations led to the classification of patients with T2DM into three distinct subtypes (A-C), with HC grouped as D. Enhanced intercellular communication, particularly through the MHC-I pathway, was evident in T2DM subtypes. Machine learning models effectively classified T2DM subtypes based on metabolic signatures, achieving an AUC > 0.84. Analysis of TF activity identified pivotal regulators, including NF-kB, STAT3, and FOXO1, associated with immune and metabolic disturbances in T2DM. Drug enrichment analysis highlighted potential therapeutic agents targeting these TFs and related pathways, including Suloctidil, Chlorpropamide, and other compounds modulating inflammatory and metabolic pathways.

Conclusion

This study underscores significant immunometabolic dysfunction in T2DM, characterized by alterations in immune cell composition, metabolic pathways, and intercellular communication. The identification of critical TFs and the development of drug enrichment profiles highlight the potential for personalized therapeutic strategies, emphasizing the need for integrated immunological and metabolic approaches in T2DM management.

Hyperglycemia-triggered lipid peroxidation destabilizes STAT4 and impairs anti-viral Th1 responses in type 2 diabetes

Patients with type 2 diabetes (T2D) are more susceptible to severe respiratory viral infections, but the underlying mechanisms remain elusive. Here, we show that patients with T2D and coronavirus disease 2019 (COVID-19) infections, and influenza-infected T2D mice, exhibit defective T helper 1 (Th1) responses, which are an essential component of anti-viral immunity. This defect stems from intrinsic metabolic perturbations in CD4+ T cells driven by hyperglycemia. Mechanistically, hyperglycemia triggers mitochondrial dysfunction and excessive fatty acid synthesis, leading to elevated oxidative stress and aberrant lipid accumulation within CD4+ T cells. These abnormalities promote lipid peroxidation (LPO), which drives carbonylation of signal transducer and activator of transcription 4 (STAT4), a crucial Th1-lineage-determining factor. Carbonylated STAT4 undergoes rapid degradation, causing reduced T-bet induction and diminished Th1 differentiation. LPO scavenger ameliorates Th1 defects in patients with T2D who have poor glycemic control and restores viral control in T2D mice. Thus, this hyperglycemia-LPO-STAT4 axis underpins reduced Th1 activity in T2D hosts, with important implications for managing T2D-related viral complications.

Investigation into changes in inflammatory and immune cell markers in pre-diabetic patients from Durban, South Africa

The prevalence of pre-diabetes is increasing in rapidly urbanizing cities, especially in individuals aged 25 - 45 years old. Studies also indicate that this condition is associated with aberrant immune responses that are also influenced by environmental factors. This study sought to investigate changes in the concentration of immune cells and select inflammatory markers in patients with pre-diabetes in Durban, South Africa. Blood samples collected from King Edward Hospital, after obtaining ethics approval, were divided into non-diabetic (ND), pre-diabetic (PD) and type 2 diabetic (T2D) using ADA criteria. In each sample, the concentration of immune cells and select inflammatory markers were determined. The results showed a significant increase in eosinophil and basophil levels in the PD group as compared to the ND group. Compared to ND, the PD and T2D groups had significant increases in serum TNFα, CD40L and fibrinogen concentrations. Additionally, there were decreases in serum CRP, IL-6, and P-selectin in the PD group while these markers increased in the T2D group. These findings were indicative of immune activation and highlight the impact of pre-diabetes in this population. More studies are recommended with a higher number of samples that are stratified by gender and represent the gender ratio in the city.

Omega-3 Fatty Acids Weaken Lymphocyte Inflammatory Features and Improve Glycemic Control in Nonobese Diabetic Goto-Kakizaki Rats

BACKGROUND/OBJECTIVES

Goto-Kakizaki (GK) rats exhibit insulin resistance and type 2 diabetes mellitus (T2DM) without obesity. This study explored the effects of ω-3 fatty acid supplementation on T lymphocyte polarization in Wistar (WT) and GK rats.

METHODS

They were administered ω-3 fatty acid-rich fish oil (FO) containing eicosapentaenoic (540 mg/g) and docosahexaenoic acids (100 mg/g) by oral gavage at 2 g/kg, thrice a week for 8 weeks. The control groups (WT CT and GK CT) received the same volume of water. The following groups were investigated: GK CT, n = 14; GK ω-3, n = 15; Wistar CT, n = 15; and Wistar ω-3, n = 11. Glucose and insulin tolerance tests (GTT and ITT) were performed. Fasting plasma insulinemia and glycemia were measured. After euthanasia, the lymphocytes were extracted from the mesenteric lymph nodes.

RESULTS

The results showed that GK rats supplemented with FO had significantly improved glucose tolerance and insulin sensitivity (kITT). It also promoted greater polarization of lymphocytes toward T regulatory (Treg) features and a reduction in Th1 and Th17 profiles. Additionally, the GK ω-3 group exhibited lower cell proliferation, decreased pro-inflammatory cytokines, and increased IL-10 levels compared to the GK control.

CONCLUSIONS

In conclusion, FO supplementation benefited GK rats by improving glucose intolerance, suppressing insulin resistance, and modulating lymphocytes toward Treg polarization.

Comparative analysis of White and African American groups reveals unique lipid and inflammatory features of diabetes

Importance

African Americans have a higher prevalence of Type 2 Diabetes (T2D) compared to White groups. T2D is a health disparity clinically characterized by dysregulation of lipids and chronic inflammation. However, how the relationships among biological and sociological predictors of T2D drive this disparity remains to be addressed.

Objective

To determine characteristic plasma lipids and systemic inflammatory biomarkers contributing to diabetes presentation between White and African American groups.

Design

We performed a cross-sectional retrospective cohort study using pre-existing demographic and clinical data from two diverse studies: Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) and AllofUs. From HANDLS (N=40), we used information from wave 1 (2004). From AllofUs (N=17,339), we used data from the Registered Tier Dataset v7, available in the AllofUs researcher workbench.

Setting

HANDLS is a population-based cohort study involving 3720 participants in the Baltimore area supported by the Intramural Research Program of the National Institute on Aging. HANDLS is a longitudinal study designed to understand the sources of persistent health disparities in overall longevity and chronic disease in White and African American individuals. The AllofUs study is an NIH funded multicenter study consisting of patient-level data from 331,382 individuals from 35 hospitals in the United States aimed at sampling one million or more people living in the United States to provide a collection of broadly accessible data.

Participants

The HANDLS subcohort participants (N=40) were divided into four groups equally distributed by race, sex, and diabetes status. Groups were also matched by age, body mass index, and poverty status. The analysis pipeline consisted of evaluating the significance of the variables race and disease status using the 2-way ANOVA test and post-ANOVA comparisons using Fisher LSD test, reporting unadjusted p-values. Additionally, unsupervised (PCA) and supervised (OPLS-DA) clustering analysis was performed to determine putative biological drivers of variability and main immunological and metabolic features characterizing diabetes in White and African American groups from HANDLS. Major clinical findings were validated in a large cohort of White and African American groups with T2D in the AllofUS research study (N=17,339). AllofUs groups were of similar range in age and BMI as HANDLS. Furthermore, a linear regression model was built adjusting for age and BMI to determine differences in clinical findings between White and African American groups with T2D.

Main Outcomes and Measures

Primary outcomes using a HANDLS subcohort (N=40) were clinical parameters related to diabetes, plasma lipids determined by lipidomics and measured by mass spectrometry, and cytokine profiling using a customized panel of 52 cytokines and growth factors measured by Luminex. Outcomes evaluated in the AllofUs study (N=17,339) were clinical: cholesterol to HDL ratio, triglycerides, fasting glucose, insulin, and hemoglobin A1C.

Results

In the HANDLS subcohort, White individuals with diabetes had elevated cholesterol to HDL ratio (mean difference -1.869, p =0.0053 ) , high-sensitivity C-reactive protein (mean difference -9.135, p =0.0040), and clusters of systemic triglycerides measured by lipidomics, compared to White individuals without diabetes. These clinical markers of dyslipidemia (cholesterol to HDL ratio and triglycerides) and inflammation (hs-CRP) were not significantly elevated in diabetes in African Americans from the HANDLS subcohort. These results persisted even when controlling for statin use. Diabetes in White individuals in the HANDLS cohort was characterized by a marked elevation in plasma lipids, while an inflammatory status characterized by Th17-cytokines was predominant in the African American group from the HANDLS subcohort. We validated the key findings of elevated triglycerides and cholesterol to HDL ratio in White individuals with T2D in a sample (N=17,339) of the AllofUs study.

Conclusions and Relevance

Our results show that diabetes can manifest with healthy lipid profiles, particularly in these cohorts of African Americans. This study suggests that Th17-inflammation associated with diabetes is characteristic of African Americans, while a more classic inflammation is distinctive of White individuals from HANDLS cohort. Further, clinical markers of dyslipidemia seem to characterize diabetes presentation only in White groups, and not in African Americans.

Changes in Metabolic and Inflammatory Markers after a Combined Exercise Program in Workers: A Randomized Controlled Trial

PURPOSE

We investigated the effects of a 16-wk combined exercise training on body composition, and metabolic and inflammatory markers in sedentary middle-aged workers. We also assessed whether alterations in metabolic markers were associated with changes in health-related outcomes.

METHODS

This randomized controlled trial involved 46 participants randomly allocated into control and exercise groups. The exercise group performed 16-wk combined aerobic and resistance training for 75 min per session, 3 times a week. Fasting blood samples were collected at baseline and after 16-wk intervention to determine lipid profile, and metabolic and inflammatory markers as primary outcomes.

RESULTS

A total of 36 participants completed the intervention (53.70 ± 6.92 yr old; n = 18 in each group). Waist circumference (interaction effect: F = 7.423, P = 0.002), fat mass (interaction effect: F = 5.070, P = 0.011), and muscle mass (interaction effect: F = 5.420, P = 0.007) were improved in the exercise group compared with the control group. Fasting glucose increased after the 16-wk follow-up (time effect: F = 73.253, P < 0.001), without an intergroup difference. Insulin levels were greater in the control compared with exercise group (group effect: F = 6.509, P = 0.015). The control group tended to increase the homeostatic model assessment of insulin resistance index (interaction effect: F = 3.493, P = 0.070) and to decrease the QUICKI index (interaction effect: F = 3.364, P = 0.075) to a greater extent compared with the exercise group. Exercise group reduced leptin (interaction effect: F = 11.175, P = 0.002) and adiponectin (interaction effect: F = 4.437, P = 0.043) concentrations in a greater magnitude than the control group. Interleukin (IL)-6 (time effect: F = 17.767, P < 0.001) and tumor necrosis factor α (time effect: F = 9.781, P = 0.004) concentrations decreased after the intervention, without an intergroup difference. IL-17A levels increased in the control compared with exercise group (interaction effect: F = 5.010, P = 0.033). Effects on adiponectin, IL-6, and IL-17A levels seem to depend on baseline body mass index, age, and sex. Percentage changes in leptin correlated positively with changes in homeostatic model assessment of insulin resistance index in the exercise ( r = 0.565, P = 0.015) and control ( r = 0.670, P = 0.002) groups.

CONCLUSIONS

A combined training program can be an effective strategy to improve body composition and inflammatory markers and prevent marked reductions in insulin sensitivity among middle-aged workers.

Periodontitis and Diabetes Differentially Affect Inflammation in Obesity

Periodontitis (PD) potentiates systemic inflammatory diseases and fuels a feed-forward loop of pathogenic inflammation in obesity and type 2 diabetes (T2D). Published work in this area often conflates obesity with obesity-associated T2D; thus, it remains unclear whether PD similarly affects the inflammatory profiles of these 2 distinct systemic diseases. We collected peripheral blood mononuclear cells (PBMCs) from cross-sectionally recruited subjects to estimate the ability of PD to affect cytokine production in human obesity and/or T2D. We analyzed 2 major sources of systemic inflammation: T cells and myeloid cells. Bioplex quantitated cytokines secreted by PBMCs stimulated with T cell- or myeloid-targeting activators, and we combinatorially analyzed outcomes using partial least squares discriminant analysis. Our data show that PD significantly shifts peripheral T cell- and myeloid-generated inflammation in obesity. PD also changed myeloid- but not T cell-generated inflammation in T2D. T2D changed inflammation in samples from subjects with PD, and PD changed inflammation in samples from subjects with T2D, consistent with the bidirectional relationship of inflammation between these 2 conditions. PBMCs from T2D subjects with stage IV PD produced lower amounts of T cell and myeloid cytokines compared with PBMCs from T2D subjects with stage II to III PD. We conclude that PD and T2D affect systemic inflammation through overlapping but nonidentical mechanisms in obesity, indicating that characterizing both oral and metabolic status (beyond obesity) is critical for identifying mechanisms linking PD to systemic diseases such as obesity and T2D. The finding that stage IV PD cells generate fewer cytokines in T2D provides an explanation for the paradoxical findings that the immune system can appear activated or suppressed in PD, given that many studies do not report PD stage. Finally, our data indicate that a focus on multiple cellular sources of cytokines will be imperative to clinically address the systemic effects of PD in people with obesity.

Macrophages and T cells in metabolic disorder-associated cancers

Cancer and metabolic disorders have emerged as major global health challenges, reaching epidemic levels in recent decades. Often viewed as separate issues, metabolic disorders are shown by mounting evidence to heighten cancer risk and incidence. The intricacies underlying this connection are still being unraveled and encompass a complex interplay between metabolites, cancer cells and immune cells within the tumour microenvironment (TME). Here, we outline the interplay between metabolic and immune cell dysfunction in the context of three highly prevalent metabolic disorders, namely obesity; two associated liver diseases, metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH); and type 2 diabetes. We focus primarily on macrophages and T cells, the critical roles of which in dictating inflammatory response and immune surveillance in metabolic disorder-associated cancers are widely reported. Moreover, considering the ever-increasing number of patients prescribed with metabolism disorder-altering drugs and diets in recent years, we discuss how these therapies modulate systemic and local immune phenotypes, consequently impacting cancer malignancy. Collectively, unraveling the determinants of metabolic disorder-associated immune landscape and their role in fuelling cancer malignancy will provide a framework essential to therapeutically address these highly prevalent diseases.

Impact of hyperglycemia on immune cell function: a comprehensive review

Hyperglycemia, a hallmark of diabetes and various metabolic disorders, has profound implications for immune cell function. The relationship between elevated blood glucose levels and immune cell function is a topic of significant medical interest. In this review, we aim to comprehensively review effects of hyperglycemia on various immune cell types and its clinical implications, particularly T cells, macrophages, natural killer cells, and neutrophils. It aims to consolidate current knowledge on the subject, with a focus on both type 1 and type 2 diabetes, as well as other pathological states where hyperglycemia is a concern. A comprehensive examination of recent studies and clinical data was conducted to assess effects of hyperglycemia on immune cell function. Evidence indicates that hyperglycemia can significantly alter immune cell function, with different diabetic conditions showing varied responses. Roles of key metabolic hormones in regulating T cell function highlight potential therapeutic targets for restoring immune balance. In addition, reprogramming of innate immune cells such as macrophages and natural killer cells under hyperglycemic conditions suggests a complex metabolic-immunological interface. This review will contribute to a better understanding of the link between diabetes, other metabolic disorders, and immune function. By examining recent research and clinical findings, this review will enhance our comprehension of the mechanisms at play and guide future medical strategies for managing and treating conditions associated with hyperglycemia.

Insulin resistance in nonobese type 2 diabetic Goto Kakizaki rats is associated with a proinflammatory T lymphocyte profile

Goto-Kakizaki (GK) rats develop a well-defined insulin resistance (IR) and type 2 diabetes mellitus (T2DM) without presenting obesity. The lymphocyte profile in nonobese diabetic conditions is not yet characterized. Therefore, GK rats were chosen to explore T lymphocyte (TL) dynamics at various stages (21, 60, and 120 days) compared to Wistar rats. GK rats exhibit progressive disruption of glucose regulation, with early glucose intolerance at 21 days and reduced insulin sensitivity at 60 days, confirming IR. Glucose transporter 1 (GLUT1) expression was consistently elevated in GK rats, suggesting heightened TL activation. T-regulatory lymphocyte markers diminished at 21 days. However, GK rats showed increased Th1 markers and reduced Gata-3 expression (crucial for Th2 cell differentiation) at 120 days. These findings underscore an early breakdown of anti-inflammatory mechanisms in GK rats, indicating a proinflammatory TL profile that may worsen chronic inflammation in T2DM.

Blue mussel (Mytilus edulis) water extract ameliorates intestinal immune response in high-fat diet-streptozotocin-induced diabetic mice

Diabetes mellitus is a metabolic disease characterized by high blood glucose levels or hyperglycemia. Diabetes causes a decrease in immune function in the human body. Mytilus edulis has been identified as having anti-inflammatory properties and the ability to improve inflammation. Thus, this study aimed to investigate the function of Matsu M. edulis water extract (MWE) in mediating the regulation of immune responses and dysregulating the intestinal immune system in hyperglycemia mouse models. The mice were treated with MWE for seven weeks. The results showed that treatment with MWE has the ability to decrease triglyceride and total cholesterol concentrations. MWE also increases the interleukin (IL)-10 concentration and natural killer cell activation. It also improves the phagocytic capacity of monocytes in the colon and the proliferative capacity of lymphocytes in the mesentery. Furthermore, MWE also regulates the IL-6 concentration and the ratio of T helper 17 cells to regulatory T cells. Collectively, this extract can improve dyslipidemia, inflammatory responses, and dysregulation of the intestinal immune system. Therefore, M. edulis water extract can be used as an alternative treatment to reduce diabetes complications.

Regulatory T cells protect against diabetic cardiomyopathy in db/db mice

AIMS/INTRODUCTION

Regulatory T cells (Tregs) have protected against many cardiovascular diseases. This study was intended to explore the effect of Tregs on diabetic cardiomyopathy (DCM) using a db/db mouse model.

MATERIALS AND METHODS

Eight-week-old male db/db mice were randomly divided into four groups: the control group, administered 200 μL phosphate-buffered saline; the small-dose Treg group, administered 105 Tregs; the large-dose Treg group, administered 106 Tregs; and the PC group, administered 100 μg anti-CD25 specific antibody (PC61) and 106 Tregs. After 12 weeks, mice were euthanized. Transthoracic echocardiography was carried out at the beginning and end of the experiment. Relevant basic experiments to evaluate the effects of Tregs on DCM were carried out.

RESULTS

Echocardiography showed that the impaired diastolic and systolic functions were significantly improved in mice administered large-dose Tregs. Large-dose Tregs significantly ameliorated myocardial hypertrophy and fibrosis, and decreased hypertrophic gene expression and collagen deposition. The protective effects of Tregs on diabetic hearts were associated with decreased oxidative stress, inflammatory response and apoptosis. In addition, Tregs promoted the activation of the phosphatidylinositol 3-kinase-protein kinase B signaling pathway, whereas they inhibited extracellular signal-regulated kinase 1/2 and Jun N-terminal kinase phosphorylation, which might be responsible for the cardioprotective role of Tregs against DCM.

CONCLUSIONS

Tregs ameliorated myocardial hypertrophy and fibrosis, improved cardiac dysfunction, and protected against DCM progression in db/db mice. The mechanisms involved a decrease of inflammatory response, oxidative stress and apoptosis, which might be mediated by phosphatidylinositol 3-kinase-protein kinase B and mitogen-activated protein kinase pathways. Hence, Tregs might serve as a promising therapeutic approach for DCM treatment.

LL37/self-DNA complexes mediate monocyte reprogramming

LL37 alone and in complex with self-DNA triggers inflammatory responses in myeloid cells and plays a crucial role in the development of systemic autoimmune diseases, like psoriasis and systemic lupus erythematosus. We demonstrated that LL37/self-DNA complexes induce long-term metabolic and epigenetic changes in monocytes, enhancing their responsiveness to subsequent stimuli. Monocytes trained with LL37/self-DNA complexes and those derived from psoriatic patients exhibited heightened glycolytic and oxidative phosphorylation rates, elevated release of proinflammatory cytokines, and affected naïve CD4+ T cells. Additionally, KDM6A/B, a demethylase of lysine 27 on histone 3, was upregulated in psoriatic monocytes and monocytes treated with LL37/self-DNA complexes. Inhibition of KDM6A/B reversed the trained immune phenotype by reducing proinflammatory cytokine production, metabolic activity, and the induction of IL-17-producing T cells by LL37/self-DNA-treated monocytes. Our findings highlight the role of LL37/self-DNA-induced innate immune memory in psoriasis pathogenesis, uncovering its impact on monocyte and T cell dynamics.

Interleukin-17A in diabetic retinopathy: The crosstalk of inflammation and angiogenesis

Diabetic retinopathy (DR) is a severe ocular complication of diabetes which can leads to irreversible vision loss in its late-stage. Chronic inflammation results from long-term hyperglycemia contributes to the pathogenesis and progression of DR. In recent years, the interleukin-17 (IL-17) family have attracted the interest of researchers. IL-17A is the most widely explored cytokine in IL-17 family, involved in various acute and chronic inflammatory diseases. Growing body of evidence indicate the role of IL-17A in the pathogenesis of DR. However, the pro-inflammatory and pro-angiogenic effect of IL-17A in DR have not hitherto been reviewed. Gaining an understanding of the pro-inflammatory role of IL-17A, and how IL-17A control/impact angiogenesis pathways in the eye will deepen our understanding of how IL-17A contributes to DR pathogenesis. Herein, we aimed to thoroughly review the pro-inflammatory role of IL-17A in DR, with focus in how IL-17A impact inflammation and angiogenesis crosstalk.

T cells in obesity-associated inflammation: The devil is in the details

Obesity presents a significant health challenge, affecting 41% of adults and 19.7% of children in the United States. One of the associated health challenges of obesity is chronic low-grade inflammation. In both mice and humans, T cells in circulation and in the adipose tissue play a pivotal role in obesity-associated inflammation. Changes in the numbers and frequency of specific CD4+ Th subsets and their contribution to inflammation through cytokine production indicate declining metabolic health, that is, insulin resistance and T2D. While some Th subset alterations are consistent between mice and humans with obesity, some changes mainly characterize male mice, whereas female mice often resist obesity and inflammation. However, protection from obesity and inflammation is not observed in human females, who can develop obesity-related T-cell inflammation akin to males. The decline in female sex hormones after menopause is also implicated in promoting obesity and inflammation. Age is a second underappreciated factor for defining and regulating obesity-associated inflammation toward translating basic science findings to the clinic. Weight loss in mice and humans, in parallel with these other factors, does not resolve obesity-associated inflammation. Instead, inflammation persists amid modest changes in CD4+ T cell frequencies, highlighting the need for further research into resolving changes in T-cell function after weight loss. How lingering inflammation after weight loss affecting the common struggle to maintain lower weight is unknown. Semaglutide, a newly popular pharmaceutical used for treating T2D and reversing obesity, holds promise for alleviating obesity-associated health complications, yet its impact on T-cell-mediated inflammation remains unexplored. Further work in this area could significantly contribute to the scientific understanding of the impacts of weight loss and sex/hormones in obesity and obesity-associated metabolic decline.

The amelioration effect of antidiabetic agents on cytokine expression in patients with type 2 diabetes mellitus

Inflammation is a condition that is closely linked to diabetes mellitus type 2 (T2DM), short for T2DM several different antidiabetic medications have been produced to regulate hyperglycemia, with indications that these therapies may have anti-inflammatory effects along with their glucose-lowering efficacy. Thus, this research was planned to explore the impact of antidiabetic agents on the cytokine expression levels -interleukin (IL)-1β, IL-6, IL-17, and IL-37 when patients have T2DM. In this study, 168 eligible subject matter was split into two groups: 50 healthy individuals and 118 cases with T2DM, who were classified into two subgroups: 30 untreated patients and 88 patients treated with metformin-based therapy. The outcome exhibited a significant increase within HbA1c% and proinflammatory cytokines (i.e., IL-1β, IL- 6, and IL-17), whereas IL-37 decreased considerably in untreated cases with T2DM compared to those in subjects who are healthy. Furthermore, the results showed increased levels Regarding waist size, body mass index and assessment using that homeostasis model, cholesterol, triglycerides, low-density lipoprotein levels, and heart danger elements in untreated cases with T2DM in comparison with hygienic subjects. Notably, treated patients with T2DM revealed an ameliorative impact on HbA1c, IL-6, IL-17, IL-37, IL-1β levels and lipid profile compared with untreated patients with T2DM. Antidiabetic agents may have a beneficial activity on the inflammatory status by reducing blood glucose levels, hyperlipidemia, and proinflammatory cytokines. The anti-inflammatory activity of IL-37 can apply a potentially effective therapeutic goal in treating T2DM and its complications.

Exploring the Interplay between Fatty Acids, Inflammation, and Type 2 Diabetes

Around 285 million people worldwide currently have type 2 diabetes and it is projected that this number will be surpassed by 2030. Therefore, it is of the utmost importance to enhance our comprehension of the disease's development. The regulation of diet, obesity, and inflammation in type 2 diabetes is believed to play a crucial role in enhancing insulin sensitivity and reducing the risk of onset diabetes. Obesity leads to an increase in visceral adipose tissue, which is a prominent site of inflammation in type 2 diabetes. Dyslipidemia, on the other hand, plays a significant role in attracting activated immune cells such as macrophages, dendritic cells, T cells, NK cells, and B cells to visceral adipose tissue. These immune cells are a primary source of pro-inflammatory cytokines that are believed to promote insulin resistance. This review delves into the influence of elevated dietary free saturated fatty acids and examines the cellular and molecular factors associated with insulin resistance in the initiation of inflammation induced by obesity. Furthermore, it explores novel concepts related to diet-induced inflammation and its relationship with type 2 diabetes.

Plasmacytoid dendritic cells contribute to vascular endothelial dysfunction in type 2 diabetes

Objective

Type 2 diabetes (T2D) is associated with an increased risk of cardiovascular disease due to macro- and microvascular dysfunction. This study aimed to investigate the potential involvement of plasmacytoid dendritic cells (pDCs) in T2D-related vascular dysfunction.

Approach and results

pDCs were isolated from db/db and control mice. It was found that pDCs from db/db mice impaired endothelial cell eNOS phosphorylation in response to ATP and decreased vascular endothelium-dependent relaxation compared to pDCs from control mice. Moreover, isolated CD4+ cells from control mice, when stimulated overnight with high glucose and lipids, and isolated pDCs from db/db mice, display elevated levels of ER stress, inflammation, and apoptosis markers. Flow cytometry revealed that pDC frequency was higher in db/db mice than in controls. In vivo, the reduction of pDCs using anti-PDCA-1 antibodies in male and female db/db mice for 4 weeks significantly improved vascular endothelial function and eNOS phosphorylation.

Conclusion

pDCs may contribute to vascular dysfunction in T2D by impairing endothelial cell function. Targeting pDCs with anti-PDCA-1 antibodies may represent a promising therapeutic strategy for improving vascular endothelial function in T2D patients. This study provides new insights into the pathogenesis of T2D-related vascular dysfunction and highlights the potential of immunomodulatory therapies for treating this complication. Further studies are warranted to explore the clinical potential of this approach.

Mitochondrial quality control and its emerging role in the pathogenesis of diabetic kidney disease

Most eukaryotic cells have mitochondrial networks that can change in shape, distribution, and size depending on cellular metabolic demands and environments. Mitochondrial quality control is critical for various mitochondrial functions including energy production, redox homeostasis, intracellular calcium handling, cell differentiation, proliferation, and cell death. Quality control mechanisms within mitochondria consist of antioxidant defenses, protein quality control, DNA damage repair systems, mitochondrial fusion and fission, mitophagy, and mitochondrial biogenesis. Defects in mitochondrial quality control and disruption of mitochondrial homeostasis are common characteristics of various kidney cell types under hyperglycemic conditions. Such defects contribute to diabetes-induced pathologies in renal tubular cells, podocytes, endothelial cells, and immune cells. In this review, we focus on the roles of mitochondrial quality control in diabetic kidney disease pathogenesis and discuss current research evidence and future directions.

Monocyte adhesive hyaluronan matrix induced by hyperglycemia in diabetic lung injuries

Infiltrated pre-inflammatory monocytes and macrophages have important roles in the induction of diabetic lung injuries, but the mechanism mediating their infiltration is still unclear. Here, we showed that airway smooth muscle cells (SMCs) activated monocyte adhesion in response to hyperglycemic glucose (25.6 mM) by significantly increasing hyaluronan (HA) in the cell matrix, with concurrent 2- to 4-fold increases in adhesion of U937 monocytic-leukemic cells. The HA-based structures were attributed directly to the high-glucose and not to increased extracellular osmolality, and they required growth stimulation of SMCs by serum. Treatment of SMCs with heparin in high-glucose induces synthesis of a much larger HA matrix, consistent with our observations in the glomerular SMCs. Further, we observed increases in tumor necrosis factor-stimulated gene-6 (TSG-6) expression in high-glucose and high-glucose plus heparin cultures, and the heavy chain (HC)-modified HA structures existed on the monocyte-adhesive cable structures in high-glucose and in high-glucose plus heparin-treated SMC cultures. Interestingly, these HC-modified HA structures were unevenly distributed along the HA cables. Further, the in vitro assay with recombinant human TSG-6 and the HA14 oligo showed that heparin has no inhibitory activity on the TSG-6-induced HC-transfer to HA, consistent with the results from SMC cultures. These results support the hypothesis that hyperglycemia in airway smooth muscle induces the synthesis of a HA matrix that recruits inflammatory cells and establishes a chronic inflammatory process and fibrosis that lead to diabetic lung injuries.

Diabetes and climate change: current evidence and implications for people with diabetes, clinicians and policy stakeholders

Climate change will be a major challenge for the world's health systems in the coming decades. Elevated temperatures and increasing frequencies of heat waves, wildfires, heavy precipitation and other weather extremes can affect health in many ways, especially if chronic diseases are already present. Impaired responses to heat stress, including compromised vasodilation and sweating, diabetes-related comorbidities, insulin resistance and chronic low-grade inflammation make people with diabetes particularly vulnerable to environmental risk factors, such as extreme weather events and air pollution. Additionally, multiple pathogens show an increased rate of transmission under conditions of climate change and people with diabetes have an altered immune system, which increases the risk for a worse course of infectious diseases. In this review, we summarise recent studies on the impact of climate-change-associated risk for people with diabetes and discuss which individuals may be specifically prone to these risk conditions due to their clinical features. Knowledge of such high-risk groups will help to develop and implement tailored prevention and management strategies to mitigate the detrimental effect of climate change on the health of people with diabetes.

Causal relationship between circulating immune cells and the risk of type 2 diabetes: a Mendelian randomization study

Objectives

Though type 2 diabetes (T2D) has been known as a metabolic disease caused by multiple factors, the etiology remains insufficiently understood. Here, we aimed to figure out whether circulating immune cell profiles causally impact T2D liability.

Methods

We applied one genome-wide association study (GWAS) summary statistics of blood traits in 563,085 participants from the Blood Cell Consortium and another GWAS of flow cytometric profile of lymphocyte subsets comprising 3,757 Sardinians to identify genetically predicted blood immune cells. We also obtained GWAS summary statistics in 898,130 individuals from the DIAGRAM Consortium to evaluate genetically predicted T2D. We primarily used inverse variance weighted (IVW) and weighted median methods to perform Mendelian randomization analyses and sensitivity analyses to evaluate heterogeneity and pleiotropy.

Results

For circulating blood leukocyte and its subpopulations, the increase of genetically predicted circulating monocyte count was causally correlated with a higher risk of T2D [odds ratio (OR) = 1.06, 95% confidence interval (CI) = 1.02-1.10, p = 0.0048]. For lymphocyte subsets, CD8⁺ T cell and CD4⁺ CD8^dim T cell count were identified with causal effect on T2D susceptibility (CD8⁺ T cell: OR = 1.09, 95% CI = 1.03-1.17, p = 0.0053; CD4⁺ CD8^dim T cell: OR = 1.04, 95% CI = 1.01-1.08, p = 0.0070). No pleiotropy was determined.

Conclusions

These findings demonstrated that higher circulating monocyte and T-lymphocyte subpopulation predicted increased T2D susceptibility, which confirmed the immunity predisposition for T2D. Our results may have the potential to provide new therapeutic targets for the diagnosis and treatment of T2D.

Coronavirus Disease 2019, Diabetes, and Inflammation: A Systemic Review

People with cardiometabolic diseases [namely type 2 diabetes (T2D), obesity, or metabolic syndrome] are more susceptible to coronavirus disease 2019 (COVID-19) infection and endure more severe illness and poorer outcomes. Hyperinflammation has been suggested as a common pathway for both diseases. To examine the role of inflammatory biomarkers shared between COVID-19 and cardiometabolic diseases, we reviewed and evaluated published data using PubMed, SCOPUS, and World Health Organization COVID-19 databases for English articles from December 2019 to February 2022. Of 248 identified articles, 50 were selected and included. We found that people with diabetes or obesity have (i) increased risk of COVID-19 infection; (ii) increased risk of hospitalization (those with diabetes have a higher risk of intensive care unit admissions) and death; and (iii) heightened inflammatory and stress responses (hyperinflammation) to COVID-19, which worsen their prognosis. In addition, COVID-19-infected patients have a higher risk of developing T2D, especially if they have other comorbidities. Treatments controlling blood glucose levels and or ameliorating the inflammatory response may be valuable for improving clinical outcomes in these patient populations. In conclusion, it is critical for health care providers to clinically evaluate hyperinflammatory states to drive clinical decisions for COVID-19 patients.

Maternal DNA methylation signatures of arsenic exposure is associated with adult offspring insulin resistance in the Strong Heart Study

Exposure to low to moderate arsenic (As) levels has been associated with type 2 diabetes (T2D) and other chronic diseases in American Indian communities. Prenatal exposure to As may also increase the risk for T2D in adulthood, and maternal As has been associated with adult offspring metabolic health measurements. We hypothesized that T2D-related outcomes in adult offspring born to women exposed to low to moderate As can be evaluated utilizing a maternally-derived molecular biosignature of As exposure. Herein, we evaluated the association of maternal DNA methylation with incident T2D and insulin resistance (Homeostatic model assessment of insulin resistance [HOMA2-IR]) in adult offspring. For DNA methylation, we used 20 differentially methylated cytosine-guanine dinucleotides (CpG) previously associated with the sum of inorganic and methylated As species (ΣAs) in urine in the Strong Heart Study (SHS). Of these 20 CpGs, we found six CpGs nominally associated (p < 0.05) with HOMA2-IR in a fully adjusted model that included clinically relevant covariates and offspring adiposity measurements; a similar model that adjusted instead for maternal adiposity measurements found three CpGs nominally associated with HOMA2-IR, two of which overlapped the offspring adiposity model. After adjusting for multiple comparisons, cg03036214 remained associated with HOMA2-IR (q < 0.10) in the offspring adiposity model. The odds ratio of incident T2D increased with an increase in maternal DNA methylation at one HOMA2-IR associated CpG in the model adjusting for offspring adiposity, cg12116137, whereas adjusting for maternal adiposity had a minimal effect on the association. Our data suggests offspring adiposity, rather than maternal adiposity, potentially influences the effects of maternal DNAm signatures on offspring metabolic health parameters. Here, we have presented evidence supporting a role for epigenetic biosignatures of maternal As exposure as a potential biomarker for evaluating risk of T2D-related outcomes in offspring later in life.

Pneumocystis pneumonia in a patient with diabetes mellitus: A case report

RATIONALE

Pneumocystis pneumonia (PCP) is an opportunistic infection of patients with congenital or acquired immunodeficiency. It is most frequently occurred in human immunodeficiency virus (HIV) infection, organ transplantation, leukemia, and immunosuppressive therapy. Here we describe the rare case of PCP in a non-HIV-infected diabetic patient and find possible reasons for the association through a literature review.

PATIENT CONCERNS

A 65-years-old male was admitted to our hospital due to a 10-year history of abnormal blood glucose levels and edema of both lower extremities for half a month. However, the patient developed a high fever and progressive dyspnea during hospitalization.

DIAGNOSES

The patient had elevated blood sugar levels, a low white blood cell count within normal limits, and severe lymphopenia. His blood G test and lactate dehydrogenase levels increased significantly. Multiple sputa and bronchoalveolar lavage fluid specimens for Pneumocystis jirovecii (PJ) nucleic acid detection were positive. Chest computed tomography scan demonstrated hazy patchy shadows in the lungs suspected to be pulmonary infections. No tumor, transplantation, or an autoimmune disease was found in the examinations. The patient was diagnosed with PCP finally.

INTERVENTIONS

A combination of oral trimethoprim-sulfamethoxazole and intravenous caspofungin was administered immediately against PJ. The patient was also treated with noninvasive ventilator-assisted ventilation, subcutaneous insulin, and hemodialysis therapy.

OUTCOMES

The patient was discharged home finally with a fair general condition and was followed up without respiratory symptoms.

LESSONS

The compromised immunity in HIV-negative patients with diabetes may be related to lymphocyte decrease and dysfunction, which may cause diabetic patients prone to PJ. Although PCP is rare in diabetes, it should be paid attention to the high rate of misdiagnosis and missed diagnosis.

Peripheral Blood Mononuclear Cells from Patients with Type 1 Diabetes and Diabetic Retinopathy Produce Higher Levels of IL-17A, IL-10 and IL-6 and Lower Levels of IFN-γ-A Pilot Study

Inflammation is key to the pathogenesis of diabetic retinopathy (DR). This prospective study investigated alterations in inflammatory cytokines in peripheral blood mononuclear cells (PBMCs) in 41 people with type 1 diabetes (T1D), sub-grouped into mild non-proliferative DR (mNPDR; n = 13) and active and inactive (each n = 14) PDR. Age/gender-matched healthy controls (n = 13) were included. PBMCs were isolated from blood samples. Intracellular cytokine expression by PBMCs after 16-h stimulation (either E. coli lipopolysaccharide (LPS), phorbol 12-myristate 13-acetate plus ionomycin, D-glucose or D-mannitol) were assessed by flow cytometry. Cytokine production in plasma, non-stimulated and LPS-stimulated PBMC supernatant was also assessed. Increased BMC IL-10 secretion and reduced expression of IL-6 and IFN-γ in CD3⁺ cells were observed in mNPDR. Reduced IL-6 and IL-10 secretion, and higher levels of intracellular IL-6 expression, especially in CD11b⁺ PBMCs, was detected in aPDR; levels were positively correlated with DR duration. Patients with T1D demonstrated increased intracellular expression of IL-17A in myeloid cells and reduced IFN-γ expression in CD3⁺ cells. Plasma levels of IL-1R1 were increased in mNPDR compared with controls. Results suggest that elevated PBMC-released IL-10, IL-6, in particular myeloid-produced IL-17A, may be involved in early stages of DR. IL-6-producing myeloid cells may play a role in PDR development.

Immunologic, metabolic and genetic impact of diabetes on tuberculosis susceptibility

Due to the increasing prevalence of diabetes mellitus (DM) globally, the interaction between DM and major global diseases like tuberculosis (TB) is of great public health significance, with evidence of DM having about a three-fold risk for TB disease. TB defense may be impacted by diabetes-related effects on immunity, metabolism, and gene transcription. An update on the epidemiological aspects of DM and TB, and the recent trends in understanding the DM-associated immunologic, metabolic, and genetic mechanisms of susceptibility to TB will be discussed in this review. This review highlights gaps in the incomplete understanding of the mechanisms that may relate to TB susceptibility in type 2 DM (T2DM). Understanding these three main domains regarding mechanisms of TB susceptibility in T2DM patients can help us build practical treatment plans to lessen the combined burden of the diseases in rampant areas.

Advances in T Cells Based on Inflammation in Metabolic Diseases

With the increasing incidence of metabolic diseases year by year and their impact on the incidence of cardiovascular diseases, metabolic diseases have attracted great attention as a major health care problem, but there is still no effective treatment. Oxidative stress and inflammation are the main mechanisms leading to metabolic diseases. T cells are involved in the inflammatory response, which can also regulate the development of metabolic diseases, CD4+ T cells and CD8+ T cells are mainly responsible for the role. Th1 and Th17 differentiated from CD4+ T promote inflammation, while Th2 and Treg inhibit inflammation. CD8+ T cells also contribute to inflammation. The severity and duration of inflammatory reactions can also lead to different degrees of progression of metabolic diseases. Moreover, mTOR, PI3K-Akt, and AMPK signaling pathways play unique roles in the regulation of T cells, which provide a new direction for the treatment of metabolic diseases in the future. In this review, we will elaborate on the role of T cells in regulating inflammation in various metabolic diseases, the signaling pathways that regulate T cells in metabolic diseases, and the latest research progress.

The role of the adaptive immune system and T cell dysfunction in neurodegenerative diseases

The adaptive immune system and associated inflammation are vital in surveillance and host protection against internal and external threats, but can secondarily damage host tissues. The central nervous system is immune-privileged and largely protected from the circulating inflammatory pathways. However, T cell involvement and the disruption of the blood-brain barriers have been linked to several neurodegenerative diseases including Parkinson's disease, Alzheimer's disease, and multiple sclerosis. Under normal physiological conditions, regulatory T cells (Treg cells) dampen the inflammatory response of effector T cells. In the pathological states of many neurodegenerative disorders, the ability of Treg cells to mitigate inflammation is reduced, and a pro-inflammatory environment persists. This perspective review provides current knowledge on the roles of T cell subsets (e.g., effector T cells, Treg cells) in neurodegenerative and ocular diseases, including uveitis, diabetic retinopathy, age-related macular degeneration, and glaucoma. Many neurodegenerative and ocular diseases have been linked to immune dysregulation, but the cellular events and molecular mechanisms involved in such processes remain largely unknown. Moreover, the role of T cells in ocular pathologies remains poorly defined and limited literature is available in this area of research. Adoptive transfer of Treg cells appears to be a vital immunological approach to control ocular pathologies. Similarities in T cell dysfunction seen among non-ocular neurodegenerative diseases suggest that this area of research has a great potential to develop better therapeutic agents for ocular diseases and warrants further studies. Overall, this perspective review article provides significant information on the roles of T cells in numerous ocular and non-ocular neurodegenerative diseases.

T cells dominate peripheral inflammation in a cross-sectional analysis of obesity-associated diabetes

OBJECTIVE

Myeloid cells dominate metabolic disease-associated inflammation (metaflammation) in mouse obesity, but the contributions of myeloid cells to the peripheral inflammation that fuels sequelae of human obesity are untested. This study used unbiased approaches to rank contributions of myeloid and T cells to peripheral inflammation in people with obesity across the spectrum of metabolic health.

METHODS

Peripheral blood mononuclear cells (PBMCs) from people with obesity with or without prediabetes or type 2 diabetes were stimulated with T cell-targeting CD3/CD28 or myeloid-targeting lipopolysaccharide for 20 to 72 hours to assess cytokine production using Bio-Plex. Bioinformatic modeling ranked cytokines with respect to their predictive power for metabolic health. Intracellular tumor necrosis factor α was quantitated as a classical indicator of metaflammation.

RESULTS

Cytokines increased over 72 hours following T cell-, but not myeloid-, targeted stimulation to indicate that acute myeloid inflammation may shift to T cell inflammation over time. T cells contributed more tumor necrosis factor α to peripheral inflammation regardless of metabolic status. Bioinformatic combination of cytokines from all cohorts, stimuli, and time points indicated that T cell-targeted stimulation was most important for differentiating inflammation in diabetes, consistent with previous identification of a mixed T helper type 1/T helper type 17 cytokine profile in diabetes.

CONCLUSIONS

T cells dominate peripheral inflammation in obesity; therefore, targeting T cells may be an effective approach for prevention/management of metaflammation.

T-cell Metabolism as Interpreted in Obesity-associated Inflammation

The appreciation of metabolic regulation of T-cell function has exploded over the past decade, as has our understanding of how inflammation fuels comorbidities of obesity, including type 2 diabetes. The likelihood that obesity fundamentally alters T-cell metabolism and thus chronic obesity-associated inflammation is high, but studies testing causal relationships remain underrepresented. We searched PubMed for key words including mitochondria, obesity, T cell, type 2 diabetes, cristae, fission, fusion, redox, and reactive oxygen species to identify foundational and more recent studies that address these topics or cite foundational work. We investigated primary papers cited by reviews found in these searches and highlighted recent work with >100 citations to illustrate the state of the art in understanding mechanisms that control metabolism and thus function of various T-cell subsets in obesity. However, "popularity" of a paper over the first 5 years after publication cannot assess long-term impact; thus, some likely important work with fewer citations is also highlighted. We feature studies of human cells, supplementing with studies from animal models that suggest future directions for human cell research. This approach identified gaps in the literature that will need to be filled before we can estimate efficacy of mitochondria-targeted drugs in clinical trials to alleviate pathogenesis of obesity-associated inflammation.

Variable frequencies of peripheral T-lymphocyte subsets in the diabetes spectrum from type 1 diabetes through latent autoimmune diabetes in adults (LADA) to type 2 diabetes

T lymphocytes are key players in the pathogenesis of autoimmune diabetes. We recruited subjects with T1D (n=81), LADA (n=82), T2D (n=95) and NGT (n=218) and analyzed the percentages of T-lymphocyte subsets, including T helper 1 (Th1), T helper 2 (Th2), T helper 17 (Th17), T cytotoxic 1 (Tc1), regulatory T cells (Tregs), effector T (Teff), naïve T, central memory T (Tcm), and effector memory T (Tem) cells by flow cytometry. LADA patients possessed similar frequencies of IFN-γ⁺CD4⁺ T (Th1), IFN-γ⁺CD8⁺ T and CD4⁺ Teff cells compared with T1D patients, but much lower than those of NGT subjects. Like T2D patients, LADA patients had increased frequencies of CD4⁺ Tem and CD8⁺ Tem cells with respect to T1D and NGT subjects. In LADA patients, Th2 cells were decreased while CD4⁺ Tcm cells were increased compared with NGT subjects. Notably, we observed significant negative correlations between the CD4⁺ Tcm cell frequency and C-peptide in LADA subjects. These data demonstrates that LADA patients possess T-cell subset changes resembling both T1D and T2D and represent the middle of the diabetes spectrum between T1D and T2D. Based on these T-cell subset alterations, we speculate that autoimmunity-induced β-cell destruction and inflammation-induced insulin resistance might both be involved in the pathogenesis of LADA.

A Review of COVID-19 in Relation to Metabolic Syndrome: Obesity, Hypertension, Diabetes, and Dyslipidemia

Although severe cases and mortality of coronavirus disease 2019 (COVID-19) are proportionally infrequent, these cases are strongly linked to patients with conditions of metabolic syndrome (obesity, hypertension, diabetes, and dyslipidemia). However, the pathophysiology of COVID-19 in relation to metabolic syndrome is not well understood. Thus, the goal of this secondary literature review was to examine the relationship between severe acute respiratory syndrome (SARS-CoV-2) infection and the individual conditions of metabolic syndrome.

The objective of this secondary literature review was achieved by examining primary studies, case studies, and other secondary studies, to obtain a comprehensive perspective of theories and observations of COVID-19 etiology with metabolic syndrome. The most extensive research was available on the topics of diabetes, hypertension, and obesity, which yielded multiple (and sometimes conflicting) hypothetical pathophysiology. The sources on dyslipidemia and COVID-19 were scarcer and failed to provide an equally comprehensive image, highlighting the need for further research.

It was concluded that hypertension had the strongest correlation with COVID-19 incidence (followed by obesity), yet the causative pathophysiology was ambiguous; most likely related to cardiovascular, angiotensin-converting enzyme 2 (ACE-2)-related complications from renin-angiotensin-aldosterone system (RAAS) imbalance. Obesity was also positively correlated to the severity of COVID-19 cases and was believed to contribute to mechanical difficulties with respiration, in addition to hypothetical connections with the expression of ACE-2 on abundant adipose tissue. Diabetes was believed to contribute to COVID-19 severity by producing a chronic inflammatory state and interfering with neutrophil and T-cell function. Furthermore, there were indications that COVID-19 may induce acute-onset diabetes and diabetic ketoacidosis. Lastly, dyslipidemia was concluded to potentially facilitate SARS-CoV-2 infection by enhancing lipid rafts and immunosuppressive functions. There were also indications that cholesterol levels may have prognostic indications and that statins may have therapeutic benefits.

The Promising Role of Microbiome Therapy on Biomarkers of Inflammation and Oxidative Stress in Type 2 Diabetes: A Systematic and Narrative Review

Background

One in 10 adults suffer from type 2 diabetes (T2D). The role of the gut microbiome, its homeostasis, and dysbiosis has been investigated with success in the pathogenesis as well as treatment of T2D. There is an increasing volume of literature reporting interventions of pro-, pre-, and synbiotics on T2D patients.

Methods

Studies investigating the effect of pro-, pre-, and synbiotics on biomarkers of inflammation and oxidative stress in T2D populations were extracted from databases such as PubMed, Scopus, Web of Science, Embase, and Cochrane from inception to January 2022.

Results

From an initial screening of 5,984 hits, 47 clinical studies were included. Both statistically significant and non-significant results have been compiled, analyzed, and discussed. We have found various promising pro-, pre-, and synbiotic formulations. Of these, multistrain/multispecies probiotics are found to be more effective than monostrain interventions. Additionally, our findings show resistant dextrin to be the most promising prebiotic, followed closely by inulin and oligosaccharides. Finally, we report that synbiotics have shown excellent effect on markers of oxidative stress and antioxidant enzymes. We further discuss the role of metabolites in the resulting effects in biomarkers and ultimately pathogenesis of T2D, bring attention toward the ability of such nutraceuticals to have significant role in COVID-19 therapy, and finally discuss few ongoing clinical trials and prospects.

Conclusion

Current literature of pro-, pre- and synbiotic administration for T2D therapy is promising and shows many significant results with respect to most markers of inflammation and oxidative stress.

Changes of Th17 cells, regulatory T cells, Treg/Th17, IL-17 and IL-10 in patients with type 2 diabetes mellitus: a systematic review and meta-analysis

PURPOSE

The aim of this study was to investigate the changes of Helper T cells 17 (Th17 cells), Regulatory T cells (Treg cells), Treg/Th17, Interleukin-17 (IL-17) and Interleukin-10 (IL-10) in patients with type 2 diabetes mellitus (T2DM).

METHODS

Four electronic resource databases were searched from their inception to 1 August 2021. Case-control studies about changes of Th17 cells, Treg cells, Treg/Th17, IL-17 and IL-10 in patients with T2DM were retrieved. We performed this meta-analysis via RevMan V.5.3 and Stata14.

RESULTS

20 studies with 1242 individuals were included in the meta-analysis. Compared with the controls, the patients with T2DM had significantly increased levels of percentage of Th17 cells (SMD, 1.74; 95% CI, 0.47-3.01; p < 0.001), IL-17 (SMD, 2.17; 95% CI, 0.06-4.28; p < 0.001), IL-10 (SMD, 1.20; 95% CI, 0.81-1.59; p = 0.003), but decreased levels of percentage of Treg cells (SMD, -1.17; 95% CI, -2.22 to -0.13; p < 0.001) and Treg/Th17 ratio (SMD, -4.43; 95% CI, -7.07 to -1.78; p < 0.001). Subgroup analysis showed that percentage of CD4⁺CD25⁺FOXP3⁺ Tregs (SMD, -2.36; 95% CI, -3.19 to -1.52; p = 0.003) in patients was notably lower than controls. While not significant changes were found in the percentage of CD4⁺CD25⁺Tregs (SMD, 0.03; 95% CI, -0.34-0.40; p = 0.63) between patients and controls. For plasma or serum IL-10, a higher plasma IL-10 level (SMD,1.37; 95% CI, 0.92-1.82; p = 0.01) was observed in T2DM. While serum IL-10 (SMD, 0.73; 95% CI, 0.35-1.12; p = 0.79) had no obvious difference between patients and controls. For ELISA or flow cytometry, IL-10 (SMD, 1.2; 95% CI, 0.71-1.70; p = 0.001) was higher in T2DM patients by using detection method of ELISA. Yet IL-10 using flow cytometry and subgroup analysis of IL-17 had no significant differences.

CONCLUSIONS

Adaptive immune system indeed plays an essential role in the process of T2DM. Imbalance between Th17 and Treg triggers pro-inflammatory environment in patients with T2DM.

Human Kidney Organoids and Tubuloids as Models of Complex Kidney Disease

Kidney organoids derived from pluripotent stem cells and epithelial organoids derived from adult tissue (tubuloids) have been used to study various kidney disorders with a strong genetic component, such as polycystic kidney disease, Wilms tumor, and congenital nephrotic syndrome. However, complex disorders without clear genetic associations, such as acute kidney injury and many forms of chronic kidney disease, are only just beginning to be investigated using these in vitro approaches. Although organoids are a reductionist model, they contain clinically relevant cell populations that may help to elucidate human-specific pathogenic mechanisms. Thus, organoids may complement animal disease models to accelerate the translation of laboratory proof-of-concept research into clinical practice. This review discusses whether kidney organoids and tubuloids are suitable models for the study of complex human kidney disease and highlights their advantages and limitations compared with monolayer cell culture and animal models.

Clinical Significance of COVID-19 and Diabetes: In the Pandemic Situation of SARS-CoV-2 Variants including Omicron (B.1.1.529)

Simple Summary

Amidst the dual pandemics of diabetes and coronavirus disease 2019 (COVID-19), with the constant emergence of novel variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a vicious cycle has been created, i.e., a hyperglycemic state contributes to the severe clinical course of COVID-19, which in turn has deleterious effects on glycometabolism and in some cases causes new-onset diabetes. Here, we present a comprehensive review of the current literature on the clinical and experimental findings associated with the interrelationship between diabetes and COVID-19. To control disease outcomes and glucometabolic complications in COVID-19, this issue is still being investigated.

Abstract

The coronavirus disease 2019 (COVID-19) global pandemic, which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), remains uncontrolled, with the spread of emerging variants. According to accumulating evidence, diabetes is one of the leading risk factors for a severe COVID-19 clinical course, depending on the glycemic state before admission and during COVID-19 hospitalization. Multiple factors are thought to be responsible, including an altered immune response, coexisting comorbidity, and disruption of the renin-angiotensin system through the virus–host interaction. However, the precise underlying mechanisms remain under investigation. Alternatively, the focus is currently on the diabetogenic and ketosis-prone potential of SARS-CoV-2 itself, even for probable triggers of stress and steroid-induced hyperglycemia in COVID-19. In this article, we present a comprehensive review of the recent literature on the clinical and experimental findings associated with diabetes and COVID-19, and we discuss their bidirectional relationship, i.e., the risk for an adverse prognosis and the deleterious effects on glycometabolism. Accurate assessments of the incidence of new-onset diabetes induced by COVID-19 and its pathogenicity are still unknown, especially in the context of the circulation of SARS-CoV-2 variants, such as Omicron (B.1.1.529), which is a major challenge for the future.

Immunoregulatory Intestinal Microbiota and COVID-19 in Patients with Type Two Diabetes: A Double-Edged Sword

Coronavirus disease 2019, or COVID-19, is a major challenge facing scientists worldwide. Alongside the lungs, the system of organs comprising the GI tract is commonly targeted by COVID-19. The dysbiotic modulations in the intestine influence the disease severity, potentially due to the ability of the intestinal microbiota to modulate T lymphocyte functions, i.e., to suppress or activate T cell subpopulations. The interplay between the lungs and intestinal microbiota is named the gut-lung axis. One of the most usual comorbidities in COVID-19 patients is type 2 diabetes, which induces changes in intestinal microbiota, resulting in a pro-inflammatory immune response, and consequently, a more severe course of COVID-19. However, changes in the microbiota in this comorbid pathology remain unclear. Metformin is used as a medication to treat type 2 diabetes. The use of the type 2 diabetes drug metformin is a promising treatment for this comorbidity because, in addition to its hypoglycemic action, it can increase amount of intestinal bacteria that induce regulatory T cell response. This dual activity of metformin can reduce lung damage and improve the course of the COVID-19 disease.

Regulation of Immune Cell Function by Nicotinamide Nucleotide Transhydrogenase

Redox homeostasis is elemental for the normal physiology of all cell types. Cells use multiple mechanisms to regulate the redox balance tightly. The onset and progression of many metabolic and aging-associated diseases occur due to the dysregulation of redox homeostasis. Thus, it is critical to identify and therapeutically target mechanisms that precipitate abnormalities in redox balance. Reactive oxygen species (ROS) produced within the immune cells regulate homeostasis, hyperimmune and hypoimmune cell responsiveness, apoptosis, immune response to pathogens, and tumor immunity. Immune cells have both cytosolic and organelle-specific redox regulatory systems to maintain appropriate levels of ROS. Nicotinamide nucleotide transhydrogenase (NNT) is an essential mitochondrial redox regulatory protein. Dysregulation of NNT function prevents immune cells from mounting an adequate immune response to pathogens, promotes a chronic inflammatory state associated with aging and metabolic diseases, and initiates conditions related to a dysregulated immune system such as autoimmunity. While many studies have reported on NNT in different cell types, including cancer cells, relatively few studies have explored NNT in immune cells. This review provides an overview of NNT and focuses on the current knowledge of NNT in the immune cells.

Regulatory T Cells Control Effector T Cell Inflammation in Human Prediabetes

A disparate array of plasma/serum markers provides evidence for chronic inflammation in human prediabetes, a condition that is most closely replicated by standard mouse models of obesity and metaflammation. These remain largely nonactionable and contrast with our rich understanding of inflammation in human type 2 diabetes. New data show that inflammatory profiles produced by CD4+ T cells define human prediabetes as a unique inflammatory state. Regulatory T cells (Treg) control mitochondrial function and cytokine production by CD4+ effector T cells (Teff) in prediabetes and type 2 diabetes by supporting T helper (Th)17 or Th1 cytokine production, respectively. These data suggest that Treg control of Teff metabolism regulates inflammation differentially in prediabetes compared with type 2 diabetes. Queries of genes that impact mitochondrial function or pathways leading to transcription of lipid metabolism genes identified the fatty acid importer CD36 as highly expressed in Treg but not Teff from subjects with prediabetes. Pharmacological blockade of CD36 in Treg from subjects with prediabetes decreased Teff production of the Th17 cytokines that differentiate overall prediabetes inflammation. We conclude that Treg control CD4+ T cell cytokine profiles through mechanisms determined, at least in part, by host metabolic status. Furthermore, Treg CD36 uniquely promotes Th17 cytokine production by Teff in prediabetes.