Immune regulators of inflammation in obesity-associated type 2 diabetes and coronary artery disease

Epicardial adipose tissue and cardiac lipotoxicity: A review

Epicardial adipose tissue (EAT) has morphological and physiological contiguity with the myocardium and coronary arteries, making it a visceral fat deposit with some unique properties. Under normal circumstances, EAT exhibits biochemical, mechanical, and thermogenic cardioprotective characteristics. Under clinical processes, epicardial fat can directly impact the heart and coronary arteries by secreting proinflammatory cytokines via vasocrine or paracrine mechanisms. It is still not apparent what factors affect this equilibrium. Returning epicardial fat to its physiological purpose may be possible by enhanced local vascularization, weight loss, and focused pharmacological therapies. This review centers on EAT's developing physiological and pathophysiological dimensions and its various and pioneering clinical utilities.

Immunomodulatory effects of colchicine on peripheral blood mononuclear cell subpopulations in human obesity: Data from a randomized controlled trial

OBJECTIVE

Colchicine is known to reduce inflammation and improve endothelial cell function and atherosclerosis in obesity, but there is little knowledge of the specific circulating leukocyte populations that are modulated by colchicine.

METHODS

A secondary analysis of a double-blind randomized controlled trial of colchicine 0.6 mg or placebo twice daily for 3 months on circulating leukocyte populations and regulation of the immune secretome in 35 adults with obesity was performed.

RESULTS

Colchicine altered multiple innate immune cell populations, including dendritic cells and lymphoid progenitor cells, monocytes, and natural killer cells when compared with placebo. Among all subjects and within the colchicine group, changes in natural killer cells were significantly positively associated with reductions in biomarkers of inflammation, including cyclooxygenase 2, pulmonary surfactant-associated protein D, myeloperoxidase, proteinase 3, interleukin-16, and resistin. Changes in dendritic cells were positively correlated with changes in serum heart-type fatty acid-binding protein concentrations. Additionally, colchicine treatment reduced cluster of differentiation (CD) CD4+ T effector cells and CD8+ T cytotoxic cells. Conversely, colchicine increased CD4+ and CD8+ T central memory cells and activated CD38High CD8+ T cells. Changes in CD4+ T effector cells were associated with changes in serum heart-type fatty acid-binding protein.

CONCLUSIONS

In adults with obesity, colchicine significantly affects circulating leukocyte populations involved in both innate and adaptive immune systems along with the associated inflammatory secretome.

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.

Role of NOD-Like Receptors in a Miniature Pig Model of Diabetic Renal Injuries

Activation of NOD-like receptor (NLR) signaling pathway can promote downstream cytokine and proinflammatory cytokines release, and inflammation induced by excess nutrients leads to renal metabolic injury. How the NLRs influence metabolic progress and then lead to the renal injury remains poorly investigated. Compared with rodents, minipigs are more similar to humans and are more ideal animal models for human disease research. In this study, we established a diabetic minipig model through a high-sugar and high-fat diet combined with streptozotocin (STZ) injection. Blood biological markers and renal pathological markers, expression of NLRP subfamily members (NLRP1 and NLRP3) and their downstream cytokines (precursors of IL-1β and IL-18 and mature forms of IL-1β and IL-18), expression of NLRC subfamily members (NLRC1, NLRC2, and NLRC5) and their downstream nuclear factor-κB (NF-κB) signaling pathway molecules (IKKβ, IκBα, and NF-κB p65), and inflammatory cytokines (TNF-α and interleukin-6 (IL-6)) were systematically evaluated. The expression of NLRP3 and its downstream cytokine signaling molecules, the precursors of IL-1β and IL-18, and the mature forms of IL-1β and IL-18 was significantly upregulated. The expression levels of NLRC1, NLRC2, and NLRC5 and activation of the downstream NF-κB pathway molecules phospho-IKKβ, phospho-IκBα, NF-κB p65, and phospho-NF-κB p65 were significantly increased. The TNF-α and IL-6 levels were significantly increased in diabetic pig kidneys. The TGF-β/Smad signaling molecules, TGF-β and P-SMAD2/3, were also increased. These results suggested that the metabolic inflammation activated by NLRs might play an important role in diabetic renal injuries.

Taurodeoxycholic acid and valine reverse obesity-associated augmented alloimmune responses and prolong allograft survival

Obesity initiates a chronic inflammatory network linked to perioperative complications and increased acute rejection rates in organ transplantation. Bariatric surgery is the most effective treatment of obesity recommended for morbidly obese transplant recipients. Here, we delineated the effects of obesity and bariatric surgery on alloimmunity and transplant outcomes in diet-induced obese (DIO) mice. Allograft survival was significantly shorter in DIO-mice. When performing sleeve gastrectomies (SGx) prior to transplantation, we found attenuated T cell-derived alloimmune responses resulting in prolonged allograft survival. Administering taurodeoxycholic acid (TDCA) and valine, metabolites depleted in DIO-mice and restored through SGx, prolonged graft survival in DIO-mice comparable with SGx an dampened Th1 and Th17 alloimmune responses while Treg frequencies and CD4+ T cell-derived IL-10 production were augmented. Moreover, in recipient animals treated with TDCA/valine, levels of donor-specific antibodies had been reduced. Mechanistically, TDCA/valine restrained inflammatory M1-macrophage polarization through TGR5 that compromised cAMP signaling and inhibited macrophage-derived T cell activation. Consistently, administering a TGR5 agonist to DIO-mice prolonged allograft survival. Overall, we provide novel insights into obesity-induced inflammation and its impact on alloimmunity. Furthermore, we introduce TDCA/valine as a noninvasive alternative treatment for obese transplant patients.

The Role of Obesity in the Immunopathogenesis of COVID-19 Respiratory Disease and Critical Illness

Coronavirus disease (COVID-19), the clinical syndrome caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is currently a global health pandemic with substantial morbidity and mortality. COVID-19 has cast a shadow on nearly every aspect of society, straining health systems and economies across the world. Although it is widely accepted that a close relationship exists between obesity, cardiovascular disease, and metabolic disorders on infection, we are only beginning to understand ways in which the immunological sequelae of obesity functions as a predisposing factor related to poor clinical outcomes in COVID-19. As both the innate and adaptive immune systems are each primed by obesity, the alteration of key pathways results in both an immunosuppressed and hyperinflammatory state. The present review will discuss the cellular and molecular immunology of obesity in the context of its role as a risk factor for severe COVID-19, discuss the role of cytokine storm, and draw parallels to prior viral epidemics such as severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), and 2009 H1N1.

Roles of Epicardial Adipose Tissue in the Pathogenesis of Coronary Atherosclerosis - An Update on Recent Findings

Adipose tissue serves not only as an energy store or a mechanical cushion, but also as an endocrine organ. Recent evidence revealed that perivascular adipose tissue is involved in vascular homeostasis and pathophysiology of adjacent arteries by producing various adipokines. Epicardial adipose tissue (EAT) is located between the surface of the heart and the visceral layer of the pericardium and surrounds the coronary arteries. Many clinical studies suggest that an increase in EAT volume is associated with coronary artery disease. It has been reported that exercise and some antidiabetic drugs can reduce EAT volume. In this review, we outline recent findings on the roles of EAT in the pathogenesis of coronary atherosclerosis.

Nomogram developed with selenoprotein S (SelS) genetic variation and clinical characteristics predicting risk of coronary artery disease in a Chinese population

BACKGROUND

Selenoprotein S (SelS) is a novel selenoprotein encoded by the SelS gene on chromosome 15q26.3. SelS is associated with the development of diabetes, dyslipidemia and macrovascular complications. However, the relationship between genetic polymorphisms of SelS and coronary artery disease (CAD) remains unclear.

METHODS

In the present study, we genotyped four single nucleotide polymorphisms (rs117613208, rs117512970, rs986500879, rs542989868) of SelS gene using direct sequencing method in a case-control study (576 CAD cases and 452 control subjects). Furthermore, we developed a predictive model using SelS genetic variation and clinical variables to predict risk of CAD.

RESULTS

We found that rs117613208 T allele was more frequent in the CAD cases than that in the controls. Logistic regression analysis suggested after adjustment of other confounders, the difference remained significant between the two groups [odds ratio (OR) =2.107, 95% confidence interval (CI): 1.239-3.583, P<0.006]. Using SelS rs117613208 T allele, age, smoking, diabetes, hypertension, apolipoprotein A1 (apoA1), and lipoprotein A [Lp(a)] (GASDLY score), we developed a diagnostic model of CAD (AUC: 0.806, 95% CI: 0.776-0.836, P<0.001, sensitivity: 74.7%, specificity:75.5%).

CONCLUSIONS

The present study suggested that genetic polymorphism of SelS was independent associated with CAD and GASDLY score may be a novel diagnostic model for CAD in a Chinese population.

The Effects of Diabetes and Diabetic Medications on Bone Health

The incidence and prevalence of diabetes continues to increase, and proper understanding of the adverse effects on bone metabolism is important. This review attempts to discuss the pathophysiology of the effects of diabetes and diabetic medications on bone metabolism and bone health. In addition, this review will address the mechanisms resulting in increased fracture risk and delayed bone healing to better treat and manage diabetic patients in the orthopedic clinical setting.

Pharmacological potential of the combination of Salvia miltiorrhiza (Danshen) and Carthamus tinctorius (Honghua) for diabetes mellitus and its cardiovascular complications

Metabolic syndrome, such as diabetes mellitus, obesity, atherosclerosis, and high blood pressure (HBP), are closely linked pathophysiologically. However, current monotherapies for metabolic syndrome fail to target the multifactorial pathology via multiple mechanisms, as well as resolving the dysfunctionality of the cells and organs of the body. We aimed to provide a comprehensive and up-to-date review of the pharmacological advances, therapeutic potential, and phytochemistry of Salvia miltiorrhiza, Carthamus tinctorius, and Danhong injection (DHI). We discussed the molecular mechanisms of the bioactive constituents relating to diabetes mellitus and metabolic disease for further research and drug development. Interestingly, Salvia miltiorrhiza, Carthamus tinctorius, and DHI have anti-inflammatory, anti-glycemic, anti-thrombotic, and anti-cancer properties; and they mainly act by targeting the dysfunctional vasculatures including the inflammatory components of the disease to provide vascular repair as well as resolving oxidative stress. The major bioactive chemical constituents of these plants include polyphenolic acids, diterpene compounds, carthamin, and hydroxysafflor yellow A. Treatment of diabetes mellitus and its associated cardiovascular complication requires a comprehensive approach involving the use of appropriate traditional Chinese medicine formula. Danshen, Honghua, and DHI target the multiple risk factors regulating the physiologic function of the body and restore normalcy, apart from the traditional advice on exercise and diet control as treatment options in a metabolic syndrome patient.

[Muramyldipeptide - based compounds in current medicine: focus on glucosaminylmuramyl dipeptide]

The role of immune mechanisms in the pathogenesis of almost all human diseases shown in recent decades, increase in antibiotic resistance and secondary immunodeficiency, aging of the population and widespread use of immunosuppressive drugs and procedures suggest a wider use of immunomodulators in current clinical practice, but the use of most of them limits the lack of knowledge. The most promising compounds for the development as immunomodulating agents and adjuvants for a wide range of vaccines are low molecular weight fragments of peptidoglycan - muramylpeptides. The article describes the mechanisms of action of muramylpeptides, their biological effects and properties of medicines developed on their basis. Special emphasis is placed to glucosaminylmuramyl dipeptide registered in the Russian Federation under the trade name Likopid, which is currently the best - studied drug in its group. The results of Likopid studies when used as a prophylactic and therapeutic agent for infections of various localization in adults and children, for oncological diseases and complications of chemotherapy and radiation therapy, psoriasis, atopic and other diseases are presented. It is emphasized that in diseases associated with human papillomavirus and plaque psoriasis, according to current criteria of evidence - based medicine, Likopid should be classified as drug with level A efficacy (high efficiency in 80-100% of patients). High safety of Likopid in adults and children, including newborns, is noted.

MicroRNAs or Long Noncoding RNAs in Diagnosis and Prognosis of Coronary Artery Disease

Coronary artery disease (CAD) is the result of atherosclerotic plaque development in the wall of the coronary arteries. The underlying mechanism involves atherosclerosis of the arteries of the heart which is a relatively complex process comprising several steps. In CAD, atherosclerosis induces functional and structural changes. The pathogenesis of CAD results from various changes in and interactions between multiple cell types in the artery walls; these changes mainly include endothelial cell (EC) dysfunction, vascular smooth muscle cell (SMC) alteration, lipid deposition and macrophage activation. Various blood markers associated with an increased risk for cardiovascular endpoints have been identified; however, few have yet been shown to have a diagnostic impact or important clinical implications that would affect patient management. Noncoding RNAs, especially microRNAs (miRNAs) and long noncoding RNAs (lncRNAs), can be stable in plasma and other body fluids and could therefore serve as biomarkers for some diseases. Many studies have shown that some miRNAs and lncRNAs play key roles in heart and vascular development and in cardiac pathophysiology. Thus, we summarize here the latest research progress, focusing on the molecular mechanism of miRNAs and lncRNAs in CAD, with the intent of seeking new targets for the treatment of heart disease.

Acyl-CoA: cholesterol acyltransferases-2 gene polymorphism is associated with increased susceptibility to coronary artery disease in Uygur population in Xinjiang, China

BACKGROUND

Acyl-CoA: cholesterol acyltransferases (ACAT) is the only enzyme that catalyzes the synthesis of cholesterol esters (CE) from free cholesterol and long-chain fatty acyl-CoA and plays a critical role in cellular cholesterol homeostasis. In the present study, our primary objective was to explore whether the single-nucleotide polymorphisms (SNPs) in ACAT-2 gene were associated with coronary artery disease (CAD) in Uygur subjects, in Xinjiang, China.

METHODS

We designed a case-control study including 516 CAD patients and 318 age- and sex-matched control subjects. Using the improved multiplex ligation detection reaction (iMLDR) method, we genotyped two SNPs (rs28765985 and rs7308390) of ACAT-2 gene in all subjects.

RESULTS

We found that the genotypes, the dominant model (CC + CT vs TT) and over-dominant model (CT vs CC + TT) of rs28765985 were significantly different between CAD patients and the controls (P=0.027, P=0.012 and P=0.035, respectively). The rs28765985 C allele was associated with a significantly elevated CAD risk [CC/CT vs TT: odds ratio (OR) = 1.48, 95% confidence interval (CI) = 1.02-2.16, P=0.04] after adjustment for confounders. The TC and LDL-C levels were significantly higher in rs28765985 CC/CT genotypes than that in TT genotypes (P<0.05).

CONCLUSIONS

Rs28765985 of ACAT-2 gene are associated with CAD in Uygur subjects. Subjects with CC/CT genotype or C allele of rs28765985 were associated with an increased risk of CAD.

An increased waist-to-hip ratio is a key determinant of atherosclerotic burden in overweight subjects

AIMS

The association of overweight status and cardiovascular disease is not clear. In this study we aimed to investigate coronary atherosclerotic disease, evaluated as coronary artery calcium score (CACs), in overweight patients with or without abdominal obesity as defined by waist-to-hip ratio (WHR).

METHODS

We enrolled 276 patients aged between 40 and 70 years, with a body mass index of 25-29.9 kg/m² and at least one cardiovascular risk factor. Exclusion criteria were history of diabetes, cardiovascular or renal disease. Patients were stratified in high WHR (H-WHR) or low WHR (L-WHR) group according to WHR (≥ 0.85 for women and ≥ 0.90 for men) and underwent multi-detector computed tomography for CACs. Mean carotid intima-media thickness (IMT) and plaque presence were equally assessed.

RESULTS

CACs was higher in the H-WHR group compared to L-WHR (9.05 [0.0-83.48] vs 0.0 [0.0-64.7] AU, p < 0.01); the prevalence of CACs > 0 in the H-WHR group was significantly higher than subjects with L-WHR (59.6% vs 38.5%, p < 0.001). Moreover, H-WHR group had higher mean IMT (0.64 [0.56-0.72] vs 0.59 [0.55-0.67] mm, p < 0.05) and higher carotid plaque prevalence (63.7% vs 50.8%, p < 0.05) compared to subjects with L-WHR. Logistic regression showed that H-WHR was associated with presence of CACs and carotid plaque (p < 0.01). In a multiple linear regression, WHR was positively associated with CACs and IMT (p < 0.01).

CONCLUSIONS

H-WHR is a marker of coronary and peripheral atherosclerotic burden in overweight patients.

Dioscin protects against coronary heart disease by reducing oxidative stress and inflammation via Sirt1/Nrf2 and p38 MAPK pathways

Cardiovascular diseases are common diseases in Sweden as in most countries. In 2016, 25,700 persons suffered from coronary heart disease (CHD) and 25% of these died within 28 days. The present study investigated whether dioscin may exert protective effects against CHD‑induced heart apoptosis, oxidative stress and inflammation in a pig model and the potential underlying mechanisms. Adult pigs were used to establish a CHD model group and 80 mg/kg dioscin was administered for 4 weeks. Histological analysis and measurement of serum levels of heart injury markers demonstrated that 80 mg/kg dioscin markedly alleviated CHD, while left ventricular ejection fraction and left ventricular systolic internal diameter measurements indicated that 80 mg/kg dioscin also increased heart function in the CHD pig model. Furthermore, western blotting demonstrated that 80 mg/kg dioscin significantly reduced protein levels of apoptosis markers in the heart of CHD model pigs, including Bcl‑2‑associated X and caspase‑3, potentially via the suppression of poly (ADP‑ribose) polymerase 1 (PARP)/p53 expression. Additionally, the results of ELISA and western blotting demonstrated that 80 mg/kg dioscin may reduce oxidative stress and inflammation in CHD model pigs through the promotion of sirtuin 1 (Sirt1)/nuclear factor erythroid 2‑related factor 2 (Nrf2) protein expression and the suppression of PARP/p53 and p38 mitogen‑activated protein kinase (MAPK) expression. The results of the current study indicate that dioscin may protect against CHD by regulating oxidative stress and inflammation via Sirt1/Nrf2 and p38 MAPK pathways.

Influence of Inflammation and Atherosclerosis in Atrial Fibrillation

BACKGROUND

Inflammation markers have been associated with cardiovascular diseases including atrial fibrillation. This arrhythmia is the most frequent, with an incidence of 38/1000 person-years.

PURPOSE OF REVIEW

The aims of this study are to discuss the association between inflammation, atherosclerosis and atrial fibrillation and its clinical implications. Atherosclerosis is a chronic inflammatory disease and inflammation is a triggering factor of atherosclerotic plaque rupture. In addition to coronary artery disease, clinical conditions identified as risk factors for atrial fibrillation (AF) are also associated with the inflammatory state such as obesity, diabetes mellitus, hypertension, heart failure, metabolic syndrome and sedentary lifestyle. Biomarkers of inflammation, oxidative stress, coagulation, and myocardial necrosis have been identified in patients with atrial fibrillation and these traditional risk factors. Some markers of inflammation were identified as predictors of recurrence of this arrhythmia, subsequent myocardial infarction, stroke by embolism, and death. Thus, approaches to manipulate the inflammatory pathways may be therapeutic interventions, benefiting patients with AF and increased inflammatory markers.

Heterogeneity in effects of genetically determined adiposity on insulin resistance and type 2 diabetes: The atherosclerosis risk in communities study

BACKGROUND

A recent genome-wide association study has identified 12 genetic variants robustly associated with body fat percentage (BF%) with diverse cardiometabolic consequences. We developed three genetic risk scores (GRSs) according to the associations of the 12 individual variants with type 2 diabetes (T2D) and test the GRSs' associations with insulin resistance and T2D in the Atherosclerosis Risk in Communities Study.

METHODS

In 6895 European-American participants, we calculated GRS-I as the number of BF%-increasing alleles from variants associated with increased risk of T2D, GRS-D from variants associated with decreased risk of T2D, and GRS-ALL from all 12 variants. Linear and logistic regression models were used to evaluate associations of the GRSs with insulin resistance and risk of T2D, respectively, adjusted for age, sex, smoking, and drinking, and additionally for body mass index (BMI).

RESULTS

GRS-D was significantly associated with decreased levels of fasting insulin (P = 0.014) and homeostasis assessment of insulin resistance (P = 0.023). While GRS-I was not associated with insulin resistance measures, it was with T2D (P = 0.002). Further adjustment for BMI did not substantially change the above associations. GRS-ALL was inversely associated with insulin resistance after controlling for covariates including BMI; GRS-ALL was not associated with T2D.

CONCLUSION

Genetically determined BF% has differential effects on cardiometabolic risk, which may partly explain the heterogeneity in obesity-induced cardiometabolic risk and have implications for developing new strategies mitigating obesity-induced cardiometabolic consequences.

Physical activity and central adiposity in a cohort of African-American adults

Background

Visceral adipose tissue (VAT) is known as an independent predictor of cardiometabolic risk and all-cause mortality, while increased physical activity has been shown to improve cardiometabolic risk. The purpose of the present study was to determine whether or not there is an association between objectively-measured physical activity and VAT in a community-based cohort of African-American adults, a population at higher-than-average risk for cardiometabolic diseases.

Methods

Free-living physical activity was quantified using accelerometry while VAT and abdominal subcutaneous fat were estimated using dual x-ray absorptiometry in a cohort of African Americans, ages 30–50 years, enrolled in the Modeling the Epidemiologic Transition Study. Univariate and multivariate analyses were used to determine the degree of association comparing moderate-to-vigorous physical activity (MVPA), vigorous activity, and sedentary behavior with measures of central adiposity including VAT, subcutaneous fat, and waist circumference.

Results

A total of 271 individuals with complete data were included in the analyses. Women, on average, had significantly more VAT and abdominal subcutaneous fat than men. There were statistically significant inverse univariate correlations between MVPA and measures of abdominal adiposity (−0.30, p < 0.001) and activity counts and adiposity (−0.31, p < 0.001) among both sexes. These significant associations remained after controlling for age, sex, and smoking status; neither alcohol consumption nor employment status were associated with abdominal adiposity. Time in sedentary behavior was not meaningfully associated with central adiposity in either sex (women: −0.02, p = 0.79; men: −0.21, p = 0.04).

Conclusions

To our knowledge, this study is the first to identify significant inverse associations between MVPA and measures of central adiposity among African American adults from a community-based cohort using an objective measure of physical activity and a validated quantitative imaging technique.

Adaptive Immunity and Metabolic Health: Harmony Becomes Dissonant in Obesity and Aging

Adipose tissue (AT) is the primary energy reservoir organ, and thereby plays a critical role in energy homeostasis and regulation of metabolism. AT expands in response to chronic overnutrition or aging and becomes a major source of inflammation that has marked influence on systemic metabolism. The chronic, sterile inflammation that occurs in the AT during the development of obesity or in aging contributes to onset of devastating diseases such as insulin resistance, diabetes, and cardiovascular pathologies. Numerous studies have shown that inflammation in the visceral AT of humans and animals is a critical trigger for the development of metabolic syndrome. This work underscores the well-supported conclusion that the inflammatory immune response and metabolic pathways in the AT are tightly interwoven by multiple layers of relatively conserved mechanisms. During the development of diet-induced obesity or age-associated adiposity, cells of the innate and the adaptive immune systems infiltrate and proliferate in the AT. Macrophages, which dominate AT-associated immune cells in mouse models of obesity, but are less dominant in obese people, have been studied extensively. However, cells of the adaptive immune system, including T cells and B cells, contribute significantly to AT inflammation, perhaps more in humans than in mice. Lymphocytes regulate recruitment of innate immune cells into AT, and produce cytokines that influence the helpful-to-harmful inflammatory balance that, in turn, regulates organismal metabolism. This review describes inflammation, or more precisely, metabolic inflammation (metaflammation) with an eye toward the AT and the roles lymphocytes play in regulation of systemic metabolism during obesity and aging. © 2017 American Physiological Society. Compr Physiol 7:1307-1337, 2017.

Epicardial adipose tissue: at the heart of the obesity complications

In recent years, the anatomic and functional contiguity of epicardial adipose tissue (EAT) to myocardium and coronary arteries has gained increasing interest for its potential pathogenetic role in obesity-related cardiac diseases. Besides its known and attributed biochemical cardioprotective properties, it is becoming evident that, in metabolic disease states, EAT-secreted bioactive molecules may play an important role in the pathogenesis of coronary artery disease and cardiac arrhythmias. EAT-derived inflammatory cytokines and reactive oxidative species may, indeed, play a part in the development of a local proatherogenic milieu by paracrine and vasocrine mechanisms of interaction. In addition, initial clinical and in vitro studies have pointed out that EAT could be a determinant of the substrate of atrial fibrillation by contributing to the structural and electrical remodeling of myocardium. This article reviews the current state of knowledge on the association of EAT with cardiac dysfunction and the potential factors mediating the cross talk between this fat depot and the underlying cardiac structures.

Metabolic syndrome and inflammation in adipose tissue occur at different times in animals submitted to a high-sugar/fat diet

Obesity is associated with low-grade inflammation, triggered in adipose tissue, which may occur due to an excess of SFA from the diet that can be recognised by Toll-like receptor-4. This condition is involved in the development of components of the metabolic syndrome associated with obesity, especially insulin resistance. The aim of the study was to evaluate the manifestation of the metabolic syndrome and adipose tissue inflammation as a function of the period of time in which rats were submitted to a high-sugar/fat diet (HSF). Male Wistar rats were divided into six groups to receive the control diet (C) or the HSF for 6, 12 or 24 weeks. HSF increased the adiposity index in all HSF groups compared with the C group. HSF was associated with higher plasma TAG, glucose, insulin and leptin levels. Homeostasis model assessment increased in HSF compared with C rats at 24 weeks. Both TNF-α and IL-6 were elevated in the epididymal adipose tissue of HSF rats at 24 weeks compared with HSF at 6 weeks and C at 24 weeks. Only the HSF group at 24 weeks showed increased expression of both Toll-like receptor-4 and NF-κB. More inflammatory cells were found in the HSF group at 24 weeks. We can conclude that the metabolic syndrome occurs independently of the inflammatory response in adipose tissue and that inflammation is associated with hypertrophy of adipocytes, which varies according to duration of exposure to the HSF.

The Immune System in Obesity: Developing Paradigms Amidst Inconvenient Truths

PURPOSE OF REVIEW

Adipose tissue (AT) houses both innate and adaptive immune systems that are crucial for preserving AT function and metabolic homeostasis. In this review, we summarize recent information regarding progression of obesity-associated AT inflammation and insulin resistance. We additionally consider alterations in AT distribution and the immune system in males vs. females and among different racial populations.

RECENT FINDINGS

Innate and adaptive immune cell-derived inflammation drives insulin resistance both locally and systemically. However, new evidence also suggests that the immune system is equally vital for adipocyte differentiation and protection from ectopic lipid deposition. Furthermore, roles of anti-inflammatory immune cells such as regulatory T cells, "M2-like" macrophages, eosinophils, and mast cells are being explored, primarily due to promise of immunotherapeutic applications. Both immune responses and AT distribution are strongly influenced by factors like sex and race, which have been largely underappreciated in the field of metabolically-associated inflammation, or meta-flammation. More studies are required to recognize factors that switch inflammation from controlled to uncontrolled in obesity-associated pathogenesis and to integrate the combined effects of meta-flammation and immunometabolism. It is critical to recognize that the AT-associated immune system can be alternately beneficial and destructive; therefore, simply blocking immune responses early in obesity may not be the best clinical approach. The dearth of information on gender and race-associated disparities in metabolism, AT distribution, and the immune system suggest that a greater understanding of such differences will be critical to develop personalized treatments for obesity and the associated metabolic dysfunction.

In obese mice, exercise training increases 11β-HSD1 expression, contributing to glucocorticoid activation and suppression of pulmonary inflammation

Exercise training is advocated for treating chronic inflammation and obesity-related metabolic syndromes. Glucocorticoids (GCs), the anti-inflammatory hormones, are synthesized or metabolized in extra-adrenal organs. This study aims to examine whether exercise training affects obesity-associated pulmonary inflammation by regulating local GC synthesis or metabolism. We found that sedentary obese (ob/ob) mice exhibited increased levels of interleukin (IL)-1β, IL-18, monocyte chemotactic protein (MCP)-1, and leukocyte infiltration in lung tissues compared with lean mice, which was alleviated by 6 wk of exercise training. Pulmonary corticosterone levels were decreased in ob/ob mice. Exercise training increased pulmonary corticosterone levels in both lean and ob/ob mice. Pulmonary corticosterone levels were negatively correlated with IL-1β, IL-18, and MCP-1. Immunohistochemical staining of the adult mouse lung sections revealed positive immunoreactivities for the steroidogenic acute regulatory protein, the cholesterol side-chain cleavage enzyme (CYP11A1), the steroid 21-hydroxylase (CYP21), 3β-hydroxysteroid dehydrogenase (3β-HSD), and type 1 and type 2 11β-hydroxysteroid dehydrogenase (11β-HSD) but not for 11β-hydroxylase (CYP11B1). Exercise training significantly increased pulmonary 11β-HSD1 expression in both lean and ob/ob mice. In contrast, exercise training per se had no effect on pulmonary 11β-HSD2 expression, although pulmonary 11β-HSD2 levels in ob/ob mice were significantly higher than in lean mice. RU486, a glucocorticoid receptor antagonist, blocked the anti-inflammatory effects of exercise training in lung tissues of obese mice and increased inflammatory cytokines in lean exercised mice. These findings indicate that exercise training increases pulmonary expression of 11β-HSD1, thus contributing to local GC activation and suppression of pulmonary inflammation in obese mice.NEW & NOTEWORTHY Treadmill training leads to a significant increase in pulmonary corticosterone levels in ob/ob mice, which is in parallel with the favorable effects of exercise on obesity-associated pulmonary inflammation. Exercise training increases pulmonary 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) expression but has no significant effect on 11β-HSD2 expression in both lean and ob/ob mice. These findings indicate that exercise training increases pulmonary expression of 11β-HSD1, thus contributing to local glucocorticoid activation and suppression of pulmonary inflammation in obese mice.

Adiponectin administration prevents weight gain and glycemic profile changes in diet-induced obese immune deficient Rag1-/- mice lacking mature lymphocytes

BACKGROUND

Obesity is associated with chronic low-grade inflammation leading to insulin resistance and diabetes. Adiponectin is an adipokine that regulates inflammatory responses. The aim of our study was to investigate whether any effects of adiponectin against obesity and insulin-resistance may depend on the adaptive immune system.

METHODS

We treated high-fat-diet fed Rag1-/- mice lacking mature lymphocytes with adiponectin over 7weeks and investigated alterations in their metabolic outcome and inflammatory state.

RESULTS

Adiponectin protects from weight gain despite a small compensatory stimulation of energy intake in mice lacking an adaptive immune system. Additionally, adiponectin protects from dysglycemia. Minor alterations in the macrophage phenotype, but not in the circulating cytokine levels, may contribute to the protective role of adiponectin against hyperglycemia and diabetes.

CONCLUSION

Adiponectin or agents increasing adiponectin may be a promising therapeutic option against obesity and hyperglycemia in immune-deficient populations.

Inflammatory Adipokines Decrease Expression of Two High Molecular Weight Isoforms of Tropomyosin Similar to the Change in Type 2 Diabetic Patients

Cardiovascular disease and cancer are increased in Type 2 diabetes. TPM1 and TPM4 genes encode proteins associated with cardiovascular and neoplastic disease. High (HMW) and low (LMW) molecular weight isoforms from TPM1 and TPM4 are altered in several cancer cells and the 3'UTR of TPM1 mRNA is tumour suppressive. Leukocytes influence cardiovascular and neoplastic disease by immunosurveillance for cancer and by chronic inflammation in Type 2 diabetes and cardiovascular disease. The aim was to determine changes in expression of isoforms from TPM1 and TPM4 genes in leukocytes from Type 2 diabetic patients and to use the leukocyte cell line THP1 to identify possible mediators of changes in the patients. Gene expression was determined by RT-qPCR. In diabetes, expression of HMW isoforms from TPM1 were markedly decreased (0.55 v 1.00; p = 0.019) but HMW isoforms from TPM4 were not significantly different (0.76 v 1.00; p = 0.205). Within individual variance in expression of HMW isoforms was very high. The change in expression in HMW isoforms from TPM1 and TPM4 was replicated in THP1 cells treated with 1 ng/ml TNFα (0.10 and 0.12 v 1.00 respectively) or 10 ng/ml IL-1α (0.17 and 0.14 v 1.00 respectively). Increased insulin or glucose concentrations had no substantial effects on TPM1 or TPM4 expression. Decreased TPM1 mRNA resulted in decreases in HMW protein levels. Expression of HMW isoforms from TPM1 is decreased in Type 2 diabetes. This is probably due to increased levels of inflammatory cytokines TNFα and IL-1α in Type 2 diabetes. Lower levels of TPM1 mRNA reduce tumour suppression and could contribute to increased cancer risk in Type 2 diabetes. Decreased HMW tropomyosin isoforms are associated with cancer. Decreased HMW isoforms give rise to cells that are more plastic, motile, invasive and prone to dedifferentiation resulting in leukocytes that are more invasive but less functionally effective.

Statin therapy and inflammation in patients with diabetes treated with high dose aspirin

BACKGROUND

Statin and aspirin form the therapeutic cornerstone in patients with coronary artery disease (CAD) and diabetes. Little is known about relationship of statins with blood thrombogenicity and inflammation in these patients.

METHODS

Two hundred nine consecutive patients with diabetes and suspected CAD undergoing elective cardiac catheterization were divided in groups based on statin treatment in the Multi-Analyte, Thrombogenic, and Genetic Markers Atherosclerosis study. Urinary 11-dehydrothromboxane B2 (11-dh-TxB2), lipid profile and oxLDL/β2GPI were measured by AspirinWorks™ ELISA assay, vertical density gradient ultracentrifugation and immunoassay respectively. Thrombelastography, and ADP- and collagen-induced light transmittance aggregometry assessed thrombogenicity. CAD was classified as none/minor [<20% diameter stenosis (DS)], moderate (20-75% DS), or severe (>75% DS).

RESULTS

Severe, moderate, and no CAD was observed in 66, 19, and 15% of patients respectively. Patients on statins had significantly lower 11-dh-TxB2, collagen-induced aggregation, total cholesterol, total LDL, LDL3, oxidized-LDL, Apo B100, and ApoB100/A1 ratio (p<0.01 for all). Statin therapy demonstrated a lower proportion of patients with high urinary 11-dh-TxB2 (>1500pg 11-dh-TxB2/mg creatinine) (25 vs. 57%, p=0.01).

CONCLUSION

Statins along with aspirin, confers additional anti-inflammatory and antithrombotic effect in diabetics with CAD. Urinary 11-dh-TxB2 may be a useful biomarker for personalizing statin therapy.

Thermogenic potential and physiological relevance of human epicardial adipose tissue

Epicardial adipose tissue is a unique fat depot around the heart that shares a close anatomic proximity and vascular supply with the myocardium and coronary arteries. Its accumulation around the heart, measured using various imaging modalities, has been associated with the onset and progression of coronary artery disease in humans. Epicardial adipose tissue is also the only fat depot around the heart that is known to express uncoupling protein 1 at both mRNA and protein levels in the detectable range. Recent advances have further indicated that human epicardial fat exhibits beige fat-like features. Here we provide an overview of the physiological and pathophysiological relevance of human epicardial fat, and further discuss whether its thermogenic properties can serve as a target for the therapeutic management of coronary heart disease in humans.

Survivorship in Immune Therapy: Assessing Chronic Immune Toxicities, Health Outcomes, and Functional Status among Long-term Ipilimumab Survivors at a Single Referral Center

Ipilimumab, a novel immune checkpoint inhibitor, is associated with long-term survival in approximately 20% of patients with advanced melanoma and is also being evaluated in the adjuvant setting. With this growing cohort of survivors, long-term health outcomes, chronic toxicities, and functional outcomes among survivors treated with ipilimumab need to be defined. Using retrospective medical record abstraction, we evaluated disease status, chronic immune- and non-immune-related health events, pharmacologic management of symptoms, and functional status in patients with melanoma, with overall survival ≥2 years following ipilimumab treatment at Vanderbilt University. Ninety patients received ipilimumab for metastatic disease or as adjuvant therapy between January 2006 and September 2012, and 33 patients survived ≥2 years, with a median overall survival of 60.1 months. Of these, 24 patients were alive at the last follow-up (73%), with 14 patients free of disease (42%). Gastrointestinal and dermatologic adverse events were frequent but largely transient. By contrast, patients with hypophysitis universally required ongoing corticosteroids, although largely remained asymptomatic with appropriate hormone replacement. Surviving patients generally had excellent performance status (ECOG 0-1 in 23 of 24). Chronic neurologic toxicities caused substantial morbidity and mortality in 2 patients who received whole-brain radiotherapy >5 years before analysis, and in one patient with chronic, painful peripheral neuropathy. No previously undescribed cardiac, pulmonary, gastrointestinal, hematologic, or neoplastic safety signals were identified. In conclusion, ipilimumab was associated with largely excellent functional outcomes among long-term survivors. Chronic endocrine dysfunction and occasional neurologic toxicity (primarily associated with whole-brain radiation) were observed in a small number of patients.