An Eclectic Cast of Cellular Actors Orchestrates Innate Immune Responses in the Mechanisms Driving Obesity and Metabolic Perturbation

The escalating problem of obesity and its multiple metabolic and cardiovascular complications threatens the health and longevity of humans throughout the world. The cause of obesity and one of its chief complications, insulin resistance, involves the participation of multiple distinct organs and cell types. From the brain to the periphery, cell-intrinsic and intercellular networks converge to stimulate and propagate increases in body mass and adiposity, as well as disturbances of insulin sensitivity. This review focuses on the roles of the cadre of innate immune cells, both those that are resident in metabolic organs and those that are recruited into these organs in response to cues elicited by stressors such as overnutrition and reduced physical activity. Beyond the typical cast of innate immune characters invoked in the mechanisms of metabolic perturbation in these settings, such as neutrophils and monocytes/macrophages, these actors are joined by bone marrow-derived cells, such as eosinophils and mast cells and the intriguing innate lymphoid cells, which are present in the circulation and in metabolic organ depots. Upon high-fat feeding or reduced physical activity, phenotypic modulation of the cast of plastic innate immune cells ensues, leading to the production of mediators that affect inflammation, lipid handling, and metabolic signaling. Furthermore, their consequent interactions with adaptive immune cells, including myriad T-cell and B-cell subsets, compound these complexities. Notably, many of these innate immune cell-elicited signals in overnutrition may be modulated by weight loss, such as that induced by bariatric surgery. Recently, exciting insights into the biology and pathobiology of these cell type-specific niches are being uncovered by state-of-the-art techniques such as single-cell RNA-sequencing. This review considers the evolution of this field of research on innate immunity in obesity and metabolic perturbation, as well as future directions.

The Impact of Obesity and Metabolic Syndrome on Vaccination Success

The increase in the prevalence of obesity represents a worldwide phenomenon which is associated with several chronic diseases. In this review, we summarize published data showing how obesity, alone or together with the metabolic syndrome, induces defects in B cells similar to those induced by aging, contributes to systemic and B cell intrinsic inflammation and increases the secretion of autoimmune antibodies. We show that obese individuals contract more bacterial, viral, and fungal infections as compared to lean controls. These include periodontal, cutaneous, gastric, and respiratory tract infections, as well as postsurgical infections occurring after solid organ transplantation and surgeries for weight loss. Moreover, because obese individuals have a compromised immune system, they respond poorly to vaccination against influenza, hepatitis B, tetanus, and rabies. The results in this review highlight the importance to vaccinate individuals with obesity and/or with metabolic syndrome to prevent morbidity from vaccine-preventable diseases.

Comparison of silver nanoparticle-induced inflammatory responses between healthy and metabolic syndrome mouse models

Silver nanoparticles (AgNPs) are utilized in surgical implants and medical textiles, thus providing access to the circulation. While research has been conducted primarily in healthy models, AgNP-induced toxicity evaluations in disease conditions are critical, as many individuals have preexisting conditions. Specifically, over 20% of United States adults suffer from metabolic syndrome (MetS). It was hypothesized that MetS may increase susceptibility to AgNP-mediated toxicity due to induction of differential inflammation and altered biodistribution. Mice were injected with 2 mg/kg AgNPs, and organs assessed for inflammatory gene expression (TNF-α, CXCL1, CXCL2, CCL2, TGF-β, HO-1, IL-4, IL-13), and Ag content. AgNPs were determined to induce differential inflammation in healthy and MetS mice. While AgNP exposure increased TNF-α, CXCL1, TGF-β, HO-1, and IL-4 expression within healthy mouse spleens, MetS-treated animals demonstrated decreased CXCL1, IL-4, and IL-13 expression. Healthy and MetS mice livers exhibited similar inflammatory responses to one another. AgNPs localized primarily to the liver and spleen, although Ag was present in all examined organs. In organs of minor AgNP deposition, such as kidney, gene expression was variable. Induction of inflammatory genes did not correspond with biodistribution, suggesting disease-related variations in AgNP-mediated adverse responses. These findings indicate that disease may influence inflammation and biodistribution, impacting AgNP clinical applications.

Vitamin D signaling maintains intestinal innate immunity and gut microbiota: potential intervention for metabolic syndrome and NAFLD

A lack of sunlight exposure, residence in the northern latitudes, and dietary vitamin D insufficiency are coprevalent with metabolic syndrome (MetS), Type 2 diabetes (T2D), and nonalcoholic fatty liver diseases (NAFLD), implying a potential causality and underlying mechanism. Whether vitamin D supplementation or treatment can improve these disorders is controversial, in part, because of the absence of large-scale trials. Experimental investigations, on the other hand, have uncovered novel biological functions of vitamin D in development, tumor suppression, and immune regulation, far beyond its original role as a vitamin that maintained calcium homeostasis. While the large intestine harbors massive numbers of microbes, the small intestine has a minimal quantity of bacteria, indicating the existence of a gating system located in the distal region of the small intestine that may restrain bacterial translocation to the small intestine. Vitamin D receptor (VDR) was found to be highly expressed at the distal region of small intestine, where the vitamin D signaling promotes innate immunity, including the expression of α-defensins by Paneth cells, and maintains the intestinal tight junctions. Thus, a new hypothesis is emerging, indicating that vitamin D deficiency may impair the intestinal innate immunity, including downregulation of Paneth cell defensins, leading to bacterial translocation, endotoxemia, systemic inflammation, insulin resistance, and hepatic steatosis. Here, we review the studies for vitamin D for innate immunity and metabolic homeostasis, and we outline the clinical trials of vitamin D for mitigating MetS, T2D, and NAFLD.

Phytohormones: Multifunctional nutraceuticals against metabolic syndrome and comorbid diseases

Metabolic syndrome is characterized by the co-occurrence of diverse symptoms initiating the development of type 2 diabetes, cardiovascular diseases, and a variety of comorbid diseases. The complex constellation of numerous comorbidities makes it difficult to develop common therapeutic approaches that ameliorate these pathological features simultaneously. The plant hormones abscisic acid, salicylic acid, auxin, and cytokinins, have shown promising anti-inflammatory and pro-metabolic effects that could mitigate several disorders relevant to metabolic syndrome. Intriguingly, besides plants, human cells and gut microbes also endogenously produce these molecules, indicating a role in the complex interplay between inflammatory responses associated with metabolic syndrome, the gut microbiome, and nutrition. Here, we introduce how bioactive phytohormones can be generated endogenously and through the gut microbiome. These molecules subsequently influence immune responses and metabolism. We also elaborate on how phytohormones can beneficially modulate metabolic syndrome comorbidities, and propose them as nutraceuticals.

Clinical effect of simvastatin combined with exercise training in the treatment of stationary chronic obstructive pulmonary disease complicated with metabolic syndrome

The aim of this study is to observe and analyze the clinical efficacy of simvastatin combined with exercise training in the treatment of stationary chronic obstructive pulmonary disease complicated with metabolic syndrome. In this study, 180 patients who had been treated for stable chronic obstructive pulmonary disease (COPD) complicated with metabolic syndrome in our hospital were enrolled as research objects. The selected patients were randomly divided into research group receiving simvastatin combined with exercise training and control group accepting routine therapy, each containing 90 cases. The therapeutic effects of the two groups were compared. The CAT score, insulin resistance index and 6 min walking distance of the two groups were compared. The results showed that compared with the control group, the improvement effect of the research group was more obvious, and the effect was better than that of the control group, p<0.05. The levels of IL-6 (interleukin-6), IL-8 (interleukin-8) and other inflammatory factors were significantly lower in the research group than those in the control group, p<0.05. Simvastatin combined with exercise training in the treatment of stationary chronic obstructive pulmonary disease with metabolic syndrome is an effective treatment, which can significantly improve the treatment effect and help patients to achieve a higher quality of life.

Safety and tolerability of experimental hookworm infection in humans with metabolic disease: study protocol for a phase 1b randomised controlled clinical trial

BACKGROUND

Abdominal obesity and presence of the metabolic syndrome (MetS) significantly increase the risk of developing diseases such as Type 2 diabetes mellitus (T2DM) with escalating emergence of MetS and T2DM constituting a significant public health crisis worldwide. Lower prevalence of inflammatory and metabolic diseases such as T2DM in countries with higher incidences of helminth infections suggested a potential role for these parasites in the prevention and management of certain diseases. Recent studies confirmed the potential protective nature of helminth infection against MetS and T2DM via immunomodulation or, potentially, alteration of the intestinal microbiota. This Phase 1b safety and tolerability trial aims to assess the effect of inoculation with helminths on physical and metabolic parameters, immune responses, and the microbiome in otherwise healthy women and men.

METHODS

Participants eligible for inclusion are adults aged 18-50 with central obesity and a minimum of one additional feature of MetS recruited from the local community with a recruitment target of 54. In a randomised, double-blind, placebo-controlled design, three groups will receive either 20 or 40 stage three larvae of the human hookworm Necator americanus or a placebo. Eligible participants will provide blood and faecal samples at their baseline and 6-monthly assessment visits for a total of 24 months with an optional extension to 36 months. During each scheduled visit, participants will also undergo a full physical examination and complete diet (PREDIMED), physical activity, and patient health (PHQ-9) questionnaires. Outcome measurements include tolerability and safety of infection with Necator americanus, changes in metabolic and immunological parameters, and changes in the composition of the faecal microbiome.

DISCUSSION

Rising cost of healthcare associated with obesity-induced metabolic diseases urgently calls for new approaches in disease prevention. Findings from this trial will provide valuable information regarding the potential mechanisms by which hookworms, potentially via alterations in the microbiota, may positively influence metabolic health.

TRIAL REGISTRATION

The protocol was registered on ANZCTR.org.au on 05 June 2017 with identifier ACTRN12617000818336. Alternatively, a Google search using the above trial registration number will yield a direct link to the trial protocol within the ANZCTR website.

Metabolic syndrome attenuates ulcerative colitis: Correlation with interleukin-10 and galectin-3 expression

BACKGROUND

Ulcerative colitis (UC) is a chronic disease characterized by inflammation of intestinal epithelium, primarily of the colon. An increasing prevalence of metabolic syndrome (MetS) in patients with UC has been documented recently. Still, there is no evidence that MetS alters the course of the UC.

AIM

To test the influence of the MetS on the severity of UC and the local and systemic immune status.

METHODS

Eighty nine patients with de novo histologically confirmed UC were divided in two groups, according to ATP III criteria: Group without MetS (no MetS) and group with MetS.

RESULTS

Clinically and histologically milder disease with higher serum level of immunosuppressive cytokine interleukin-10 (IL-10) and fecal content of Galectin-3 (Gal-3) was observed in subjects with UC and MetS, compared to subjects suffering from UC only. This was accompanied with predomination of IL-10 over pro-inflammatory cytokines tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), and interleukin-17 (IL-17) in the sera as well as Gal-3 over TNF-α and IL-17 in feces of UC patients with MetS. Further, the patients with both conditions (UC and MetS) had higher percentage of IL-10 producing and Gal-3 expressing innate and acquired immune cells in lamina propria.

CONCLUSION

Local dominance of Gal-3 and IL-10 over pro-inflammatory mediators in patients with MetS may present a mechanism for limiting the inflammatory process and subsequent tissue damage in UC.

Comparison of Two Autoimmune Dysglycemia Syndromes: Insulin Autoimmune Syndrome (IAS) and Type B Insulin Resistance Syndrome (B-IRS)

Insulin autoimmune syndrome (IAS) and type B insulin resistance syndrome (B-IRS) are rare autoimmune dysglycemia syndromes, but their treatment and prognosis are different. This study aimed to provide a basis for the clinical differential diagnosis of IAS and B-IRS. This was a retrospective study of the medical records of all patients diagnosed with IAS or B-IRS between January 2006 and March 2018 at the Chinese PLA General Hospital. Demographic, clinical, biochemistry, treatment, and follow-up data were examined. There were several different biochemical parameters between IAS (n=13) and B-IRS (n=6): white blood count (WBC, 7.05±3.06 vs. 2.70±0.73×10⁹/l, p=0.004), platelet (249±56.6 vs. 111±68.0×10⁹/l, p<0.001), serum creatine (59.0±17.8 vs. 43.1±7.05 μmol/l, p=0.013), serum albumin (42.3±5.17 vs. 33.6±3.40 g/l, p=0.002), triglyceride (median, 1.33 (1.01, 1.93) vs. 0.56 (0.50, 0.79) mmol/l, p=0.002), plasma IgG (1183±201 vs. 1832±469 mg/ml, p=0.018), IgA (328±140 vs. 469±150 mg/ml, p=0.018), and C3 (128±23.4 vs. 45.3±13.5 mg/l, p<0.001). Fasting insulin in the IAS and B-IRS patients was high (299-4708 vs. 118-851 mU/l, p=0.106), and there was a difference in 2 h oral glucose tolerance test insulin (4217-8343 mU/l vs. 274-1143 mU/l, p=0.012). Glycated hemoglobin (HbA1c) in the B-IRS patients was higher than in IAS patients (114±14.4. vs. 40.6±8.89 mmol/mol, p<0.001). Serum insulin-like growth factor-1 (IGF-1) was lower in all B-IRS patients (25±0.00 vs. 132±52.7 ng/ml, p<0.001). Although IAS and B-IRS are autoimmune hyperinsulinemic dysglycemic syndromes, several clinical parameters (body mass index, HbA1c, WBC, platelet, albumin, triglyceride, IgG, C3, and IGF-1) are different between these two syndromes.

Relationship between serum levels of immunoglobulins and metabolic syndrome in an adult population: A population study from the TCLSIH cohort study

BACKGROUND AND AIMS

Metabolic syndrome (MetS) is a combination of metabolic disorders that increase the risk of developing cardiovascular disease, and inflammation is considered as a pathological basis for MetS. Immunoglobulins (Igs) are the major secretory products of the adaptive immune system. However, no large-scale population study has focused on a possible relationship between Igs and MetS. We designed a cross-sectional study to investigate the relationship between Igs and prevalence of MetS in a large-scale adult population.

METHODS AND RESULTS

A total of 10,289 participants were recruited among residents in Tianjin, China. Metabolic syndrome was defined in accordance with the criteria of the American Heart Association scientific statements of 2009. Serum levels of Igs were determined by immunonephelometry. Multiple logistic regression models were used to assess the relationship between the quintiles of serum levels of Igs and the prevalence of MetS. The overall prevalence of MetS was 36.1%. The mean (standard deviation) values of Igs (IgG, IgE, IgM, and IgA) were 1205.7 (249.3) mg/dL, 93.1 (238.9) IU/mL, 105.7 (57.3) mg/dL, and 236.2 (97.6) mg/dL, respectively. The adjusted odds ratios (95% confidence interval) of MetS for the highest quintile of Igs (IgG, IgE, IgM, and IgA), when compared to the lowest quintile, were 0.81 (0.70, 0.95), 0.97 (0.83, 1.12), 1.13 (0.97, 1.33), and 1.52 (1.30, 1.77), respectively.

CONCLUSIONS

This study demonstrated that decreased IgG and increased IgA are independently related to a higher prevalence of MetS. The results indicate that the Igs might be useful predictive factors for MetS in the general adult population.

Cytokines and inflammation in adipogenesis: an updated review

The biological relevance of cytokines is known for more than 20 years. Evidence suggests that adipogenesis is one of the biological events involved in the regulation of cytokines, and pro-inflammatory cytokines (e.g., TNFα and IL-1β) inhibit adipogenesis through various pathways. This inhibitory effect can constrain the hyperplastic expandability of adipose tissues. Meanwhile, chronic low-grade inflammation is commonly observed in obese populations. In some individuals, the impaired ability of adipose tissues to recruit new adipocytes to adipose depots during overnutrition results in adipocyte hypertrophy, ectopic lipid accumulation, and insulin resistance. Intervention studies showed that pro-inflammatory cytokine antagonists improve metabolism in patients with metabolic syndrome. This review focuses on the cytokines currently known to regulate adipogenesis under physiological and pathophysiological circumstances. Recent studies on how inhibited adipogenesis leads to metabolic disorders were summarized. Although the interplay of cytokines and lipid metabolism is yet incompletely understood, cytokines represent a class of potential therapeutic targets in the treatment of metabolic disorders.

Fibre Intake Is Independently Associated with Increased Circulating Interleukin-22 in Individuals with Metabolic Syndrome

The positive effects of dietary fibre on gut barrier function and inflammation have not been completely elucidated. Mice studies show gut barrier disruption and diet-induced insulin resistance can be alleviated by cytokine interleukin-22 (IL-22). However, little is known about IL-22 in humans and its association with gut-beneficial nutrients like fibre. We investigated whether fibre intake was associated with circulating levels of IL-22 in 48 participants with metabolic syndrome (MetS). Bivariate analysis was used to explore associations between circulating IL-22, fibre intake, MetS factors, body composition, and cardiorespiratory fitness (peak oxygen uptake, V ˙ O2peak). Hierarchical multiple regression (HMR) was used to test the independent association of fibre intake with circulating IL-22, adjusting for variables correlated with IL-22. Circulating IL-22 was positively associated with fibre intake (rs = 0.393, p < 0.006). The HMR-adjusted model explained 40% of circulating IL-22 variability, and fibre intake significantly improved the prediction model by 8.4% (p < 0.022). Participants with fibre intake above median intake of 21.5 g/day had a significantly higher circulating IL-22 than the lower intake group (308.3 ± 454.4 vs. 69.0 ± 106.4 pg/mL, p < 0.019). Fibre intake is independently associated with increased circulating IL-22 in individuals with MetS. Findings warrant further investigations to evaluate whether changes in dietary fibre intake alter circulating IL-22, and its effects on health outcomes.

Unaccounted risk of cardiovascular disease: the role of the microbiome in lipid metabolism

PURPOSE OF REVIEW

Not all of the risk of cardiovascular disease can be explained by diet and genetics, and the human microbiome, which lies at the interface of these two factors, may help explain some of the unaccounted risk. This review examines some of the well established links between the microbiome and cardiovascular health, and proposes relatively unexplored associations.

RECENT FINDINGS

Byproducts of microbial metabolism are associated with health and disease: Trimethylamine N oxide is associated with atherosclerosis; whereas short-chain fatty acids are associated with decreased inflammation and increased energy expenditure. More broadly, a large number of association studies have been conducted to explore the connections between bacterial taxa and metabolic syndrome. In contrast, the relationship between the microbiome and triglycerides levels remains poorly understood.

SUMMARY

We suggest that deeper understanding of the molecular mechanisms that drive linkages between the microbiome and disease can be determined by replacing 16S rRNA gene sequencing with shotgun metagenomic sequencing or other functional approaches. Furthermore, to ensure translatability and reproducibility of research findings, a combination of multiple different complementary '-omic' approaches should be employed.

Central and Peripheral Inflammation Link Metabolic Syndrome and Major Depressive Disorder

Metabolic syndrome and major depression are two of the most common and debilitating disorders worldwide, occurring with significant rates of comorbidity. Recent studies have uncovered that each of these conditions is associated with chronic, low-grade inflammation. This is characterized by increased circulating pro-inflammatory cytokines, altered leukocyte population frequencies in blood, accumulation of immune cells in tissues including the brain, and activation of these immune cells. Cytokines that become elevated during obesity can contribute to the progression of metabolic syndrome by directly causing insulin resistance. During chronic stress, there is evidence that these cytokines promote depression-like behavior by disrupting neurotransmitter synthesis and signal transduction. Animal models of obesity and depression have revealed a bi-directional relationship whereby high-fat feeding and chronic stress synergize and exacerbate metabolic dysregulation and behavioral abnormalities. Although far from conclusive, emerging evidence suggests that inflammation in the central and peripheral immune system may link metabolic syndrome to major depressive disorder. In this review, we will synthesize available data supporting this view and identify critical areas for future investigation.

Increased mast cell abundance in adipose tissue of metabolic syndrome: relevance to the proinflammatory state and increased adipose tissue fibrosis

Metabolic Syndrome (MetS) affects 35% of American adults > 40 yr and portends an increased risk for both atherosclerotic cardiovascular disease (ASCVD) and diabetes. The role of mast cells in the proinflammatory state of MetS is not well elucidated. We propose that mast cells in subcutaneous adipose tissue (SAT) of MetS patients without diabetes or clinical ASCVD contribute to insulin resistance and inflammation. Matched controls ( n = 15) and MetS ( n = 19) subjects were recruited from Sacramento, CA, and selected based on Adult Treatment Panel III criteria. SAT biopsy was performed on all subjects and processed for immunohistochemistry. The SAT sections were stained using Astra Blue stain and tryptase stain for mast cells. Fasting blood was obtained for chemistries and biomarkers. Abundance of mast cells (Astra Blue stain) in SAT of MetS subjects compared with controls was increased 2.5-fold ( P < 0.0001). Mast cells correlated positively and significantly with waist circumference, glucose, triglycerides, homeostatic model of assessment-insulin resistance (HOMA-IR), AT insulin resistance, leptin, interleukin (IL)-1β, IL-6, chemerin, p38 MAPK activity, and nuclear factor κB activity in circulating monocytes. Mast cells also correlated significantly with markers of fibrosis and angiogenesis. Tryptase staining of mast cells in AT revealed a significant increase ( P = 0.008) with similar correlations. We make the novel observation that there are increased mast cells in SAT of MetS, and these mast cells correlate with insulin resistance (hepatic and adipose tissue), inflammation, and AT fibrosis. Hence, these immune cells appear to occupy a pivotal role in the pathogenesis of MetS.

Immunomodulatory nanogels overcome restricted immunity in a murine model of gut microbiome-mediated metabolic syndrome

Biomaterials-based nanovaccines, such as those made of poly(lactic-co-glycolic acid) (PLGA), can induce stronger immunity than soluble antigens in healthy wild-type mouse models. However, whether metabolic syndrome can influence the immunological responses of nanovaccines remains poorly understood. Here, we first show that alteration in the sensing of the gut microbiome through Toll-like receptor 5 (TLR5) and the resulting metabolic syndrome in TLR5 ^-/- mice diminish the germinal center immune response induced by PLGA nanovaccines. The PLGA nanovaccines, unexpectedly, further changed gut microbiota. By chronically treating mice with antibiotics, we show that disrupting gut microbiome leads to poor vaccine response in an obesity-independent manner. We next demonstrate that the low immune response can be rescued by an immunomodulatory Pyr-pHEMA nanogel vaccine, which functions through TLR2 stimulation, enhanced trafficking, and induced stronger germinal center response than alum-supplemented PLGA nanovaccines. The study highlights the potential for immunomodulation under gut-mediated metabolic syndrome conditions using advanced nanomaterials.

Mediation Effect of Neutrophil Lymphocyte Ratio on Cardiometabolic Risk Factors and Cardiovascular Events

Neutrophil to lymphocyte ratio (NLR), an inflammatory biomarker, is associated with cardiovascular events (CVEs), but its causal pathway is unknown. We aimed to explore the extent to which NLR is directly associated with CVEs or mediated through diabetes mellitus (DM), hypertension (HT) and creatinine (Cr). The study used data on 2,501 subjects from the Electricity Generating Authority of Thailand cohort 2002-2012. Two causal pathways A: NLR→(DM→Cr→HT)→CVEs and B: NLR→(DM → HT→Cr)→CVEs were constructed. A generalized structural equation model and 1,000-replication bootstrapping were applied. The incidence rate of CVE was 8.8/1000/year. Prevalence rates of HT, DM, and chronic kidney disease were 45.1%, 23.6%, and 16.5%, respectively. The total effect of NLR on CVEs was explained partly (44%) by a direct effect and partly (56%) by an indirect effect through DM, HT and Cr. For pathway A, the direct OR of NLR on CVE was 1.25 (95% CI: 1.13, 1.39); the ORs for the indirect effects of NLR on CVEs mediated through DM, Cr, and poor-controlled HT were 1.06 (95% CI: 1.01, 1.11), 1.01 (95% CI: 1.00, 1.02), and 1.07 (95% CI: 1.01, 1.14) respectively. Results were similar for pathway B. Our findings demonstrate that roughly half of the relationship between NLR and CVEs may be mediated through DM, HT and Cr.

Complement Components, C3 and C4, and the Metabolic Syndrome

INTRODUCTION

Increased systemic inflammation plays a significant role in the development of adult cardiometabolic diseases such as insulin resistance, dyslipidemia, atherosclerosis, and hypertension. The complement system is a part of the innate immune system and plays a key role in the regulation of inflammation. Of particular importance is the activation of complement components C3 and C4. C3 is produced primarily by the liver but is also produced in adipocytes, macrophages and endothelial cells, all of which are present in adipose tissues. Dietary fat and chylomicrons stimulate C3 production. Adipocytes in addition to producing C3 also have receptors for activated C3 and other complement components and thus also respond to as well as produce a target for complement. C3adesArg, also known as acylation stimulation factor, increases adipocyte triglyceride synthesis and release. These physiological effects play a significant role in the development of metabolic syndrome. Epidemiologically, obese adults and non-obese adults with cardiometabolic disease who are not obese have been shown to have increased complement levels. C4 levels also correlate with body mass index. Genetically, specific C3 polymorphisms have been shown to predict future cardiovascular events and. D decreased C4 long gene copy number is associated with increased longevity.

CONCLUSION

Future research is clearly needed to clarify the role of complement in the development of cardiovascular disease and mechanisms for its action. The complement system may provide a new area for intervention in the prevention of cardiometabolic diseases.

Effects of Millimolar Steady-State Hydrogen Peroxide Exposure on Inflammatory and Redox Gene Expression in Immune Cells from Humans with Metabolic Syndrome

Reactive oxygen species (ROS) such as hydrogen peroxide (H₂O₂) can exert opposed effects depending on the dosage: low levels can be involved in signalling and adaptive processes, while higher levels can exert deleterious effects in cells and tissues. Our aim was to emulate a chronic ex vivo oxidative stress situation through a 2 h exposure of immune cells to sustained H₂O₂ produced by glucose oxidase (GOX), at high or low production rate, in order to determine dissimilar responses of peripheral blood mononuclear cells (PBMCs) and neutrophils on ROS and cytokine production, and mitochondrial dynamics-related proteins, pro/anti-inflammatory and anti-oxidant gene expression. Immune cells were obtained from subjects with metabolic syndrome. H₂O₂ at low concentrations can trigger a transient anti-inflammatory adiponectin secretion and reduced gene expression of toll-like receptors (TLRs) in PBMCs but may act as a stimulator of proinflammatory genes (IL6, IL8) and mitochondrial dynamics-related proteins (Mtf2, NRF2, Tfam). H₂O₂ at a high concentration enhances the expression of pro-inflammatory genes (TLR2 and IL1β) and diminishes the expression of mitochondrial dynamics-related proteins (Mtf1, Tfam) and antioxidant enzymes (Cu/Zn SOD) in PBMCs. The GOX treatments produce dissimilar changes in immune cells: Neutrophils were more resistant to H₂O₂ effects and exhibited a more constant response in terms of gene expression than PBMCs. We observe emerging roles of H₂O₂ in mitochondrial dynamics and redox and inflammation processes in immune cells.

Dietary phenolic acids reverse insulin resistance, hyperglycaemia, dyslipidaemia, inflammation and oxidative stress in high-fructose diet-induced metabolic syndrome rats

This study investigated the influence of caffeic, ferulic, gallic and protocatechuic acids on high-fructose diet-induced metabolic syndrome in rats. Oral administration of the phenolic acids significantly reversed high-fructose diet-mediated increase in body mass index and blood glucose. Furthermore, phenolic acids restored high-fructose diet-mediated alterations in metabolic hormones (insulin, leptin and adiponectin). Similarly, elevated tumour necrosis factor-α, interleukin-6 and -8 were significantly lowered. Administration of phenolic acids restored High-fructose diet-mediated increase in the levels of lipid parameters and indices of atherosclerosis, cardiac and cardiovascular diseases. High-fructose diet-mediated decrease in activities of antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glucose 6-phosphate dehydrogenase) and increase in oxidative stress biomarkers (reduced glutathione, lipid peroxidation products, protein oxidation and fragmented DNA) were significantly restored by the phenolic acids. The result of this study shows protective influence of caffeic acid, ferulic acid, gallic acid and protocatechuic acid in high-fructose diet-induced metabolic syndrome.

Functions of adipose-resident immune subsets and the impact on metabolic syndrome

There is a growing appreciation of the role in the aetiology of metabolic syndrome that is played by the interplay of diet, microbiota and the interactions of immune cells and adipose cells in visceral adipose tissue. Recent studies have highlighted the programmes, properties and roles of the specialized, resident immune subsets that are abundant in adipose tissue, which may be considered a newly identified lymphoid compartment for immunology research. The findings indicate important roles for resident T effector and regulatory cells, innate lymphoid cells (ILCs), invariant natural killer T (iNKT) cells and macrophages, among others. Immunologists are at the very beginning of trying to narrate a story of complex interactions, with the need to unravel cause from effect. The enterprise will require studies in humans as well as mice, and needs to bring together the collaborative efforts of scientists and clinicians from diverse spheres including metabolic disease, diet and microbiology.

Fecal transplant from resveratrol-fed donors improves glycaemia and cardiovascular features of the metabolic syndrome in mice

Oral administration of resveratrol attenuates several symptoms associated with the metabolic syndrome, such as impaired glucose homeostasis and hypertension. Recent work has shown that resveratrol can improve glucose homeostasis in obesity via changes in the gut microbiota. Studies involving fecal microbiome transplants (FMTs) suggest that either live gut microbiota or bacterial-derived metabolites from resveratrol ingestion are responsible for producing the observed benefits in recipients. Herein, we show that obese mice receiving FMTs from healthy resveratrol-fed mice have improved glucose homeostasis within 11 days of the first transplant, and that resveratrol-FMTs is more efficacious than oral supplementation of resveratrol for the same duration. The effects of FMTs from resveratrol-fed mice are also associated with decreased inflammation in the colon of obese recipient mice. Furthermore, we show that sterile fecal filtrates from resveratrol-fed mice are sufficient to improve glucose homeostasis in obese mice, demonstrating that nonliving bacterial, metabolites, or other components within the feces of resveratrol-fed mice are sufficient to reduce intestinal inflammation. These postbiotics may be an integral mechanism by which resveratrol improves hyperglycemia in obesity. Resveratrol-FMTs also reduced the systolic blood pressure of hypertensive mice within 2 wk of the first transplant, indicating that the beneficial effects of resveratrol-FMTs may also assist with improving cardiovascular conditions associated with the metabolic syndrome.

Plasmatic free light chains as inflammatory marker in insulin resistance: comparison of metabolic syndrome with adult growth hormone deficiency

Biological functions of immunoglobulin-free light chains (FLCs), other than in chronic inflammatory diseases, are still poorly defined; the field of insulin resistance (IR) has not been investigated, despite the strict relationships with oxidative stress (OS) and inflammation. Therefore, we evaluated FLCs levels and their relationships with metabolic parameters in adult growth hormone deficiency (GHD) and metabolic syndrome (MetS), both characterized by IR. One hundred subjects were enrolled: group A, patients with GHD [n =31, 24-69 years, mean ± SEM body mass index (BMI) 26.8 ± 1.5 kg/m² ]; group B, patients with MetS (n = 29, 21-70 years, BMI 31.9 ± 1.3); group C, controls (N = 40, 21-62 years, BMI 21.6 ± 1.1). Groups were matched by age range and, for patients, by BMI. Morning blood sample was collected for metabolic parameters and FLCs, assessed by turbidimetric assay. GHD patients show levels of FLCs significantly higher than MetS and controls (mean ± SEM κ 37.21 ± 6.97, 15.27 ± 0.86, 12.34 ± 0.85 mg/l; λ 19.44 ± 2.61, 11.78 ± 0.72 and 11.67 ± 0.77 mg/l; κ/λ ratio 1.77 ± 0.13, 1.38 ± 0.09; and 1.10 ± 0.06, respectively); only κ were higher in MetS versus controls. Therefore, the ratio showed progressive declining values in GHD versus MetS versus controls. Our data show increased FLCs levels in GHD and MetS, with the highest values in the former. Both conditions show OS, but with different molecular patterns. FLCs may contribute to chronic inflammation, leading to OS, and cardiovascular complications of GHD. Prognostic and therapeutic implications require further investigation. © 2018 BioFactors, 44(5):480-484, 2018.

Metabolic syndrome: an update on diagnostic criteria, pathogenesis, and genetic links

Metabolic syndrome (MetS), today a major global public health problem, is a cluster of clinical, metabolic, and biochemical abnormalities, such as central adiposity, hypertension, insulin resistance, and dyslipidemias. These MetS-related traits significantly increase the risk of type 2 diabetes mellitus, adverse cardiac events, stroke, and hepatic steatosis. The pathogenesis of MetS is multifactorial, with the interplay of environmental, nutritional, and genetic factors. Chronic low-grade inflammation together with visceral adipose tissue, adipocyte dysfunction, and insulin resistance plays a major role in the progression of the syndrome by impairing lipid and glucose homeostasis in insulin-sensitive tissues, such as the liver, muscle, and adipocytes. Adipose-derived inflammatory cytokines and non-esterified fatty acids establish the link between central obesity IR, inflammation, and atherogenesis. Various studies have reported an association between MetS and related traits with single-nucleotide polymorphisms of different susceptibility genes. Modulation of cytokine levels, pro-oxidants, and disturbed energy homeostasis, in relation to the genetic variations, is described in this review of the recent literature, which also provides updated data regarding the epidemiology, diagnostic criteria, and pathogenesis of MetS.

l-Citrulline Supplementation: Impact on Cardiometabolic Health

Diminished bioavailability of nitric oxide (NO), the gaseous signaling molecule involved in the regulation of numerous vital biological functions, contributes to the development and progression of multiple age- and lifestyle-related diseases. While l-arginine is the precursor for the synthesis of NO by endothelial-nitric oxide synthase (eNOS), oral l-arginine supplementation is largely ineffective at increasing NO synthesis and/or bioavailability for a variety of reasons. l-citrulline, found in high concentrations in watermelon, is a neutral alpha-amino acid formed by enzymes in the mitochondria that also serves as a substrate for recycling l-arginine. Unlike l-arginine, l-citrulline is not quantitatively extracted from the gastrointestinal tract (i.e., enterocytes) or liver and its supplementation is therefore more effective at increasing l-arginine levels and NO synthesis. Supplementation with l-citrulline has shown promise as a blood pressure lowering intervention (both resting and stress-induced) in adults with pre-/hypertension, with pre-clinical (animal) evidence for atherogenic-endothelial protection. Preliminary evidence is also available for l-citrulline-induced benefits to muscle and metabolic health (via vascular and non-vascular pathways) in susceptible/older populations. In this review, we examine the impact of supplementing this important urea cycle intermediate on cardiovascular and metabolic health outcomes and identify future directions for investigating its therapeutic impact on cardiometabolic health.