Management of long-term complications from immunosuppression

This review discusses long-term complications from immunosuppressants after liver transplantation and the management of these complications. Common complications of calcineurin inhibitors include nephrotoxicity and metabolic diseases. Nephrotoxicity can be managed by targeting a lower drug level and/or adding an immunosuppressant of a different class. Metabolic disorders can be managed by treating the underlying condition and targeting a lower drug level. Gastrointestinal adverse effects and myelosuppression are common complications of antimetabolites that are initially managed with dose reduction or discontinuation if adverse events persist. Mammalian targets of rapamycin inhibitors are associated with myelosuppression, proteinuria, impaired wound healing, and stomatitis, which may require dose reduction or discontinuation. Induction agents and agents used for steroid-refractory rejection or antibody-mediated rejection are reviewed. Other rare complications of immunosuppressants are discussed as well.

N6-methyladenosine in myeloid cells: a novel regulatory factor for inflammation-related diseases

N6-methyladenosine (m6A) is one of the most abundant epitranscriptomic modifications on eukaryotic mRNA. Evidence has highlighted that m6A is altered in response to inflammation-related factors and it is closely associated with various inflammation-related diseases. Multiple subpopulations of myeloid cells, such as macrophages, dendritic cells, and granulocytes, are crucial for the regulating of immune process in inflammation-related diseases. Recent studies have revealed that m6A plays an important regulatory role in the functional of multiple myeloid cells. In this review, we comprehensively summarize the function of m6A modification in myeloid cells from the perspective of myeloid cell production, activation, polarization, and migration. Furthermore, we discuss how m6A-mediated myeloid cell function affects the progression of inflammation-related diseases, including autoimmune diseases, chronic metabolic diseases, and malignant tumors. Finally, we discuss the challenges encountered in the study of m6A in myeloid cells, intended to provide a new direction for the study of the pathogenesis of inflammation-related diseases.

Human antigen R: Exploring its inflammatory response impact and significance in cardiometabolic disorders

RNA-binding proteins (RBPs) play a crucial role in the regulation of posttranscriptional RNA networks, which can undergo dysregulation in many pathological conditions. Human antigen R (HuR) is a highly researched RBP that plays a crucial role as a posttranscriptional regulator. HuR plays a crucial role in the amplification of inflammatory signals by stabilizing the messenger RNA of diverse inflammatory mediators and key molecular players. The noteworthy correlations between HuR and its target molecules, coupled with the remarkable impacts reported on the pathogenesis and advancement of multiple diseases, position HuR as a promising candidate for therapeutic intervention in diverse inflammatory conditions. This review article examines the significance of HuR as a member of the RBP family, its regulatory mechanisms, and its implications in the pathophysiology of inflammation and cardiometabolic illnesses. Our objective is to illuminate potential directions for future research and drug development by conducting a comprehensive analysis of the existing body of research on HuR.

Adipose Tissue Immunometabolism: Unveiling the Intersection of Metabolic and Immune Regulation

UNASSIGNED

Excess body weight has become a global epidemic and a significant risk factor for developing chronic diseases, which are the leading causes of worldwide morbidities. Adipose tissue (AT), primarily composed of adipocytes, stores substantial amounts of energy and plays a crucial role in maintaining whole-body glucose and lipid metabolism. This helps prevent excessive body fat accumulation and lipotoxicity in peripheral tissues. In addition, AT contains endothelial cells and a substantial population of immune cells (constituting 60-70% of non-adipocyte cells), including macrophages, T and B lymphocytes, and natural killer cells. These resident immune cells engage in crosstalk with adipocytes, contributing to the maintenance of metabolic and immune homeostasis in AT. An exacerbated inflammatory response or inadequate immune resolution can lead to chronic systemic low-grade inflammation, triggering the development of metabolic alterations and the onset of chronic diseases. This review aims to elucidate the regulatory mechanisms through which immune cells influence AT function and energy homeostasis. We also focus on the interactions and functional dynamics of immune cell populations, highlighting their role in maintaining the delicate balance between metabolic health and obesity-related inflammation. Finally, understanding immunometabolism is crucial for unraveling the pathogenesis of metabolic diseases and developing targeted immunotherapeutic strategies. These strategies may offer innovative avenues in the rapidly evolving field of immunometabolism. (Rev Invest Clin. 2024;76(2):65-79).

Adipose tissue macrophages as potential targets for obesity and metabolic diseases

Macrophage infiltration into adipose tissue is a key pathological factor inducing adipose tissue dysfunction and contributing to obesity-induced inflammation and metabolic disorders. In this review, we aim to present the most recent research on macrophage heterogeneity in adipose tissue, with a focus on the molecular targets applied to macrophages as potential therapeutics for metabolic diseases. We begin by discussing the recruitment of macrophages and their roles in adipose tissue. While resident adipose tissue macrophages display an anti-inflammatory phenotype and promote the development of metabolically favorable beige adipose tissue, an increase in pro-inflammatory macrophages in adipose tissue has negative effects on adipose tissue function, including inhibition of adipogenesis, promotion of inflammation, insulin resistance, and fibrosis. Then, we presented the identities of the newly discovered adipose tissue macrophage subtypes (e.g. metabolically activated macrophages, CD9+ macrophages, lipid-associated macrophages, DARC+ macrophages, and MFehi macrophages), the majority of which are located in crown-like structures within adipose tissue during obesity. Finally, we discussed macrophage-targeting strategies to ameliorate obesity-related inflammation and metabolic abnormalities, with a focus on transcriptional factors such as PPARγ, KLF4, NFATc3, and HoxA5, which promote macrophage anti-inflammatory M2 polarization, as well as TLR4/NF-κB-mediated inflammatory pathways that activate pro-inflammatory M1 macrophages. In addition, a number of intracellular metabolic pathways closely associated with glucose metabolism, oxidative stress, nutrient sensing, and circadian clock regulation were examined. Understanding the complexities of macrophage plasticity and functionality may open up new avenues for the development of macrophage-based treatments for obesity and other metabolic diseases.

The clinical significance of the glucocorticoid receptors: Genetics and epigenetics

The impacts of glucocorticoids (GCs) are mainly mediated by a nuclear receptor (GR) existing in almost every tissue. The GR regulates a wide range of physiological functions, including inflammation, cell metabolism, and differentiation playing a major role in cellular responses to GCs and stress. Therefore, the dysregulation or disruption of GR can cause deficiencies in the adaptation to stress and the preservation of homeostasis. The number of GR polymorphisms associated with different diseases has been mounting per year. Tackling these clinical complications obliges a comprehensive understanding of the molecular network action of GCs at the level of the GR structure and its signaling pathways. Beyond genetic variation in the GR gene, epigenetic changes can enhance our understanding of causal factors involved in the development of diseases and identifying biomarkers. In this review, we highlight the relationships of GC receptor gene polymorphisms and epigenetics with different diseases.

Biglycan: an emerging small leucine-rich proteoglycan (SLRP) marker and its clinicopathological significance

Extracellular matrix (ECM) plays an important role in the structural organization of tissue and delivery of external cues to the cell. Biglycan, a class I small leucine-rich proteoglycans (SLRP), is a key component of the ECM that participates in scaffolding the collagen fibrils and mediates cell signaling. Dysregulation of biglycan expression can result in wide range of clinical conditions such as metabolic disorder, inflammatory disorder, musculoskeletal defects and malignancies. In this review, we aim to update our current understanding regarding the link between altered expression of biglycan and different clinicopathological states. Biglycan interacts with toll like receptors (TLR)-2 and TLR-4 on the immune cells which initiates inflammation and aggravates inflammatory disorders. ECM unbound soluble biglycan acts as a DAMP (danger associated molecular pattern) resulting in sterile inflammation. Dysregulation of biglycan expression is also observed in inflammatory metabolic conditions such as atherosclerosis and obesity. In cancer, high-biglycan expression facilitates tumor growth, invasion and metastasis which is associated with poor clinical outcome. As a pivotal structural component of the ECM, biglycan strengthens the musculoskeletal system and its absence is associated with musculoskeletal defects. Thus, SLRP biglycan is a potential marker which is significantly altered in different clinicopathological states.

Metabolic disease and adverse events from immune checkpoint inhibitors

OBJECTIVE

Obese and overweight body mass index (BMI) categories have been associated with increased immune-related adverse events (irAEs) in patients with cancer receiving immune checkpoint inhibitors (ICIs); however, the impact of being overweight in conjunction with related metabolic syndrome-associated factors on irAEs have not been investigated. We aimed to evaluate the impact of overweight and obese BMI according to metabolic disease burden on the development of irAEs.

DESIGN AND METHODS

We conducted a retrospective observational study of patients receiving ICIs at a cancer center. Our main study outcome was development of ≥grade 2 (moderate) irAEs. Our main predictor was weight/metabolic disease risk category: (1) normal weight (BMI 18.5-24.9 kg/m²)/low metabolic risk (<2 metabolic diseases [diabetes, dyslipidemia, hypertension]), (2) normal weight/high metabolic risk (≥2 metabolic diseases), (3) overweight (BMI ≥25 kg/m²)/low metabolic risk, and (4) overweight/high metabolic risk.

RESULTS

Of 411 patients in our cohort, 374 were eligible for analysis. Overall, 111 (30%) patients developed ≥grade 2 irAEs. In Cox analysis, overweight/low metabolic risk was significantly associated with ≥grade 2 irAEs (hazard ratio [HR]: 2.0, 95% confidence interval [95% CI]: 1.2-3.4) when compared to normal weight/low metabolic risk, while overweight/high metabolic risk (HR: 1.3, 95% CI: 0.7-2.2) and normal weight/high metabolic risk (HR: 1.5, 95% CI: 0.7-3.0) were not.

CONCLUSIONS

Overweight patients with fewer metabolic comorbidities were at increased risk for irAEs. This study provides an important insight that BMI should be evaluated in the context of associated metabolic comorbidities in assessing risk of irAE development and ICI immune response.

Regulation of Tissue Inflammation by 12-Lipoxygenases

Lipoxygenases (LOXs) are lipid metabolizing enzymes that catalyze the di-oxygenation of polyunsaturated fatty acids to generate active eicosanoid products. 12-lipoxygenases (12-LOXs) primarily oxygenate the 12th carbon of its substrates. Many studies have demonstrated that 12-LOXs and their eicosanoid metabolite 12-hydroxyeicosatetraenoate (12-HETE), have significant pathological implications in inflammatory diseases. Increased level of 12-LOX activity promotes stress (both oxidative and endoplasmic reticulum)-mediated inflammation, leading to damage in these tissues. 12-LOXs are also associated with enhanced cellular migration of immune cells-a characteristic of several metabolic and autoimmune disorders. Genetic depletion or pharmacological inhibition of the enzyme in animal models of various diseases has shown to be protective against disease development and/or progression in animal models in the setting of diabetes, pulmonary, cardiovascular, and metabolic disease, suggesting a translational potential of targeting the enzyme for the treatment of several disorders. In this article, we review the role of 12-LOXs in the pathogenesis of several diseases in which chronic inflammation plays an underlying role.

Emerging concepts in intestinal immune control of obesity-related metabolic disease

The intestinal immune system is an important modulator of glucose homeostasis and obesity-associated insulin resistance. Dietary factors, the intestinal microbiota and their metabolites shape intestinal immunity during obesity. The intestinal immune system in turn affects processes such as intestinal permeability, immune cell trafficking, and intestinal hormone availability, impacting systemic insulin resistance. Understanding these pathways might identify mechanisms underlying treatments for insulin resistance, such as metformin and bariatric surgery, or aid in developing new therapies and vaccination approaches. Here, we highlight evolving concepts centered on intestinal immunity, diet, and the microbiota to provide a working model of obesity-related metabolic disease.

Could targeting immunometabolism be a way to control the burden of COVID-19 infection?

This review portrays the metabolic consequences of Covid-19 infection at different stages of the clinical syndrome. It also describes how events can change when patients with metabolic problems are infected and the effects that diet and nutrition might play to influence the outcome of infection. We also discuss the types of maneuvers that could be used to reshape metabolic events and question if this approach could be a practical therapy used alone or in combination with other approaches to reduce the burden of Covid-19 infection.

Involvement of Gut Microbiota, Microbial Metabolites and Interaction with Polyphenol in Host Immunometabolism

Immunological and metabolic processes are inextricably linked and important for maintaining tissue and organismal health. Manipulation of cellular metabolism could be beneficial to immunity and prevent metabolic and degenerative diseases including obesity, diabetes, and cancer. Maintenance of a normal metabolism depends on symbiotic consortium of gut microbes. Gut microbiota contributes to certain xenobiotic metabolisms and bioactive metabolites production. Gut microbiota-derived metabolites have been shown to be involved in inflammatory activation of macrophages and contribute to metabolic diseases. Recent studies have focused on how nutrients affect immunometabolism. Polyphenols, the secondary metabolites of plants, are presented in many foods and beverages. Several studies have demonstrated the antioxidant and anti-inflammatory properties of polyphenols. Many clinical trials and epidemiological studies have also shown that long-term consumption of polyphenol-rich diet protects against chronic metabolic diseases. It is known that polyphenols can modulate the composition of core gut microbiota and interact with the immunometabolism. In the present article, we review the mechanisms of gut microbiota and its metabolites on immunometabolism, summarize recent findings on how the interaction between microbiota and polyphenol modulates host immunometabolism, and discuss future research directions.

Metabolism-Associated Molecular Patterns (MAMPs)

Metabolic diseases pose a tremendous health threat in both developed and developing countries. The pathophysiology of metabolic diseases is complex but has been shown to be closely associated with sterile inflammation, which is initiated by various danger molecules derived from metabolic overload, such as oxidized low-density lipoproteins (OxLDLs), free fatty acids (FFAs), glucose, advanced glycation end products (AGEs), and cholesterol. These danger signals are sensed by pattern recognition receptors (PRRs) to activate proinflammatory signaling pathways and promote the release of proinflammatory mediators, leading to chronic low-grade inflammation. Although these harmful metabolic stimuli are generally regarded as damage-associated molecular patterns (DAMPs), a more specific definition and accurate classification for these DAMPs is still missing. In this opinion, we classify the harmful metabolic stimuli that can incite inflammatory responses and tissue damage via instigating PRRs as metabolism-associated molecular patterns (MAMPs), and we summarize their roles in metaflammation-mediated metabolic diseases.

Cardiometabolic risk in young adults with depression and evidence of inflammation: A birth cohort study

BACKGROUND

Young adults with depression and evidence of inflammation may represent a high-risk group for cardiometabolic disorders, but studies of cardiometabolic risk in this population are scarce. We aimed to examine: (1) the prevalence of low-grade inflammation in young-adults with depression; (2) cross-sectional and longitudinal associations between cardiometabolic risk factors and depression with or without evidence of inflammation.

METHOD

The ALSPAC birth cohort participants were assessed for depression and serum high-sensitivity C-Reactive Protein (CRP) levels at age 18, alongside cardiometabolic measures (fasting insulin, fasting plasma glucose, low-density lipoprotein, high-density lipoprotein, triglycerides, smoking, alcohol intake) at age 18 years, and body mass index at ages 9, 13 and 18 years. Low-grade inflammation was defined as CRP>3 mg/L. Multinomial regression was used to examine associations of cardiometabolic markers with depression cases with and without evidence of inflammation. Sensitivity analyses were conducted to examine for interactions between depression, inflammation and cardiometabolic traits.

RESULTS

Out of 2932 participants, 215 met ICD-10 criteria for depressive episode at age 18 years; 23 (10.7 %) had CRP>3 mg/L and 57 (26.5 %) had CRP 1-3 mg/L. Depressive episode with raised CRP (>3 mg/L) was associated with higher triglycerides (adjusted OR = 2.09; 95 % C.I., 1.35-3.24), higher BMI (adjusted OR = 1.13; 95 % C.I., 1.05-1.22) and insulin insensitivity (adjusted OR = 1.12; 95 % C.I., 1.01-1.26), and longitudinally with higher BMI at ages 9 (adjusted OR = 1.27; 95 % C.I., 1.10-1.48) and 13 (adjusted OR = 1.23; 95 % C.I., 1.09-1.38). There was evidence for interaction between BMI and CRP for the risk of depression at age 18 (adjusted OR for the interaction term = 1.56; 95 % C.I. 0.98-2.02) and between CRP and depressive symptoms for the risk of increased BMI at age 18 (adjusted β for the interaction term = 0.05; 95 % C.I. 0.00-0.12).

CONCLUSIONS

A notable proportion of young adults with depression have evidence of inflammation. These individuals are at increased risk of cardiometabolic disorders. Management of cardiometabolic risk in depressed individuals with evidence of inflammation should form part of routine clinical practice.

Lactobacillus pentosus S-PT84 Prevents Low-Grade Chronic Inflammation-Associated Metabolic Disorders in a Lipopolysaccharide and High-Fat Diet C57/BL6J Mouse Model

A long-term exposure to lipopolysaccharides results in the gut inflammation and its impaired barrier function, leading to the development of metabolic disorders. In this study, the role of dietary heat killed Lactobacillus pentosus S-PT84 on preventing endotoxemia to maintain metabolic homeostasis was studied. We demonstrated that the treatment of L. pentosus S-PT84 improved the gut integrity by maintaining tight-junction protein expression, in order to suppress the infiltration of endotoxin into plasma. The systemic inflammatory responses were inhibited via reducing the secretion of TNF-α and MCP-1. Furthermore, the blood lipid profile and glucose level as well as adiponectin in both plasma and white adipose tissues (WAT) were preserved by L. pentosus S-PT84 through upregulation of PPAR-γ and IRS-1 expression in WAT. The above findings suggest that the metabolic homeostasis in mice treated with HFD and LPS was sustained by L. pentosus S-PT84, leading to reducing the early risk for progression into metabolic disorders.

3M-Brazzein as a Natural Sugar Substitute Attenuates Obesity, Metabolic Disorder, and Inflammation

Obesity is a global chronic disease linked to various diseases. Increased consumption of added sugars, especially in beverages, is a key contributor to the obesity epidemic. It is essential to reduce or replace sugar intake with low-calorie sweeteners. Here, a natural sweet protein, 3M-brazzein, was investigated as a possible sugar substitute. Mice were exposed to 3M-brazzein or 10% sucrose of equivalent sweetness, in drinking water to mimic human obesity development over 15 weeks. Consumption of 3M-brazzein in liquid form did not cause adiposity hypertrophy, resulting in 33.1 ± 0.4 g body weight and 0.90 ± 0.2 mm fat accumulation, which were 35.9 ± 0.7 g (p = 0.0094) and 1.53 ± 0.067 mm (p = 0.0031), respectively, for sucrose supplement. Additionally, 3M-brazzein did not disrupt glucose homeostasis or affect insulin resistance and inflammation. Due to its naturally low-calorie content, 3M-brazzein could also be a potential sugar substitute that reduces adiposity.

Immunoregulatory Functions of Nuclear Receptors: Mechanisms and Therapeutic Implications

Members of the nuclear receptor superfamily serve as master regulators in signaling by either positively or negatively regulating gene expression. Accumulating evidence has suggested that nuclear receptors are actively involved in immune responses, with specific roles in different immune cell compartments that contribute to both normal function and to disease development. The druggable properties of nuclear receptors have made them ideal modulatory therapeutic targets. Here, we revisit nuclear receptor biology, summarize recent advances in our understanding of the immunological functions of nuclear receptors, describe cell-type-specific roles and specific nuclear receptors in disease pathogenesis, and explore their potential as novel therapeutic targets. These nuclear receptor-dependent alterations in the immune system are amenable to pharmacological manipulation and suggest novel therapeutic strategies.

Impact of Food Additives on Gut Homeostasis

In physiological conditions, the gut is heavily infiltrated with various subsets of inflammatory cells, whose activity is tightly controlled by counter-regulatory mechanisms. Defects in such mechanisms can favour the development of chronic intestinal disorders, such as Crohn’s disease (CD) and ulcerative colitis (UC), the principal forms of inflammatory bowel diseases (IBD) in humans, as well as systemic disorders. Over the last years, the frequency of intestinal and systemic immune-inflammatory disorders has increased in previously low incidence areas, likely due to the Westernization of lifestyles, including dietary habits. The Western diet is characterized by high consumption of proteins, saturated fats and sweets, as well as by a broad use of food additives (e.g., emulsifiers, bulking agents), which are used to preserve and enhance food quality. Accumulating evidence suggests that food additives can perturb gut homeostasis, thereby contributing to promote tissue-damaging inflammatory responses. For instance, mice given the emulsifiers carboxymethylcellulose and polysorbate 80 develop dysbiosis with overgrowth of mucus-degrading bacteria. Such an effect triggers colitis in animals deficient in either interleukin-10, a cytokine exerting anti-inflammatory and regulatory functions, or Toll-like receptor 5, a receptor recognizing the bacterial flagellin. Similarly, the polysaccharide maltodextrin induces endoplasmic reticulum stress in intestinal goblet cells, thereby impairing mucus release and increasing host susceptibility to colitis. In this review, we report and discuss the current knowledge about the impact of food additives on gut homeostasis and their potential contribution to the development of inflammatory disorders.

Interleukin-6 Expression by Hypothalamic Microglia in Multiple Inflammatory Contexts: A Systematic Review

Interleukin-6 (IL-6) is a unique cytokine that can play both pro- and anti-inflammatory roles depending on the anatomical site and conditions under which it has been induced. Specific neurons of the hypothalamus provide important signals to control food intake and energy expenditure. In individuals with obesity, a microglia-dependent inflammatory response damages the neural circuits responsible for maintaining whole-body energy homeostasis, resulting in a positive energy balance. However, little is known about the role of IL-6 in the regulation of hypothalamic microglia. In this systematic review, we asked what types of conditions and stimuli could modulate microglial IL-6 expression in murine model. We searched the PubMed and Web of Science databases and analyzed 13 articles that evaluated diverse contexts and study models focused on IL-6 expression and microglia activation, including the effects of stress, hypoxia, infection, neonatal overfeeding and nicotine exposure, lipopolysaccharide stimulus, hormones, exercise protocols, and aging. The results presented in this review emphasized the role of "injury-like" stimuli, under which IL-6 acts as a proinflammatory cytokine, concomitant with marked microglial activation, which drive hypothalamic neuroinflammation. Emerging evidence indicates an important correlation of basal IL-6 levels and microglial function with the maintenance of hypothalamic homeostasis. Advances in our understanding of these different contexts will lead to the development of more specific pharmacological approaches for the management of acute and chronic conditions, like obesity and metabolic diseases, without disturbing the homeostatic functions of IL-6 and microglia in the hypothalamus.

Dietary N-Carbamylglutamate (NCG) alleviates liver metabolic disease and hepatocyte apoptosis by suppressing ERK1/2-mTOR-S6K1 signal pathway via promoting endogenous arginine synthesis in Japanese seabass (Lateolabrax japonicus)

N-Carbamylglutamate (NCG), an analogue of N-acetylglutamate (NAG), can promote the synthesis of endogenous Arginine (Arg) in mammals, but not well studied in fish. This study was conducted to investigate the capacity of Arg endogenous synthesis by NCG, and the effects of various dietary NCG doses on growth performance, hepatic health and underlying nutrient regulation metabolism on ERK1/2-mTOR-S6K1 signaling pathway in Japanese seabass (Lateolabrax japonicus). Four experimental diets were prepared with NCG supplement levels of 0 (N0), 360 (N360), 720 (N720) and 3600 (N3600) mg/kg, in which N360 was at the maximum recommended level authorized by MOA, China in fish feed, and the N720 and N3600 levels were 2 and 10-fold of N360, respectively. Each diet was fed to 6 replicates with 30 Japanese seabass (initial body weight, IBW = 11.67 ± 0.02 g) in each tank. The results showed that the dietary NCG supplementation had no significant effects on the SGR and morphometric parameters of Japanese seabass, but 360-720 mg/kg NCG inclusion promoted PPV, while the 10-fold (3600 mg/kg) overdose of NCG had remarkably negative effects with significantly reduced feed efficiency, PPV and LPV. We found that Japanese seabass can utilize 360-720 mg/kg NCG to synthesis Arg to improve the amino acid metabolism by increasing plasma Arg and up-regulating intestinal ASL gene expression. Increased plasma GST and decreased MDA indicated the improved antioxidant response. Dietary NCG inclusion decreased plasma IgM and down-regulated the mRNA levels of inflammation (TNF-α and IL8), apoptosis (caspase family) and fibrosis (TGF-β1) related genes in the liver. The immunofluorescence examination revealed significantly decreased hepatic apoptosis and necrosis signals in the NCG groups. The ameliorated liver function and histological structure were closely related to the improved lipid metabolism parameters with decreased plasma VLDL and hepatic TG and NEFA accumulation, down-regulated fatty acid and cholesterol synthesis and simultaneously increased lipolysis gene mRNA levels, which regulated by inhibiting phosphorylation of ERK1/2-mTOR-S6K1 signaling pathway. Consuming 3600 mg/kg of dietary NCG is not safe for Japanese seabass culturing with the significantly increased FCR and decreased protein and lipid retention, and reduced plasma ALB. Accordingly, the observed efficacy and safety level of dietary NCG in the diet of Japanese seabass is 720 mg/kg.

Impact of the Microbiome on the Immune System

Higher organisms are all born with general immunity as well as with, increasingly, more specific immune systems. All immune mechanisms function with the intent of aiding the body in defense against infection. Internal and external factors alike have varying effects on the immune system, and the immune response is tailored specifically to each one. Accompanying the components of the human innate and adaptive immune systems are the other intermingling systems of the human body. Increasing understanding of the body's immune interactions with other systems has opened new avenues of study, including that of the microbiome. The microbiome has become a highly active area of research over the last 10 to 20 years since the NIH began funding the Human Microbiome Project (HMP), which was established in 2007. Several publications have focused on the characterization, functions, and complex interplay of the microbiome as it relates to the rest of the body. A dysfunction between the microbiome and the host has been linked to various diseases including cancers, metabolic deficiencies, autoimmune disorders, and infectious diseases. Further understanding of the microbiome and its interaction with the host in relation to diseases is needed in order to understand the implications of microbiome dysfunction and the possible use of microbiota in the prevention of disease. In this review, we have summarized information on the immune system, the microbiome, the microbiome's interplay with other systems, and the association of the immune system and the microbiome in diseases such as diabetes and colorectal cancer.

T Cells in Adipose Tissue: Critical Players in Immunometabolism

Adipose tissue performs immunoregulatory functions in addition to fat storage. Various T cells in different fat depots either help maintain metabolic homeostasis under healthy conditions or contribute to metabolic disorders in pathological conditions such as obesity, diabetes, cardiovascular diseases, or even cancer. These T cells play critical roles in immunometabolism, which refers to the intersection of immunity and metabolism. Numerous studies have examined the presence and changes of different T cell subsets, including helper T cells, regulatory T cells, cytotoxic T cells, and natural killer T cells, in adipose depots in health and diseases. In this review, we will discuss the adipose tissue niches that influence the patterns and functions of T cell subsets and in turn the impact of these T cells on cell- or body-based immunometabolism accounting for health and obesity.

Inflammaging: a new immune-metabolic viewpoint for age-related diseases

Ageing and age-related diseases share some basic mechanistic pillars that largely converge on inflammation. During ageing, chronic, sterile, low-grade inflammation - called inflammaging - develops, which contributes to the pathogenesis of age-related diseases. From an evolutionary perspective, a variety of stimuli sustain inflammaging, including pathogens (non-self), endogenous cell debris and misplaced molecules (self) and nutrients and gut microbiota (quasi-self). A limited number of receptors, whose degeneracy allows them to recognize many signals and to activate the innate immune responses, sense these stimuli. In this situation, metaflammation (the metabolic inflammation accompanying metabolic diseases) is thought to be the form of chronic inflammation that is driven by nutrient excess or overnutrition; metaflammation is characterized by the same mechanisms underpinning inflammaging. The gut microbiota has a central role in both metaflammation and inflammaging owing to its ability to release inflammatory products, contribute to circadian rhythms and crosstalk with other organs and systems. We argue that chronic diseases are not only the result of ageing and inflammaging; these diseases also accelerate the ageing process and can be considered a manifestation of accelerated ageing. Finally, we propose the use of new biomarkers (DNA methylation, glycomics, metabolomics and lipidomics) that are capable of assessing biological versus chronological age in metabolic diseases.

Human gut microbiome: hopes, threats and promises

The microbiome has received increasing attention over the last 15 years. Although gut microbes have been explored for several decades, investigations of the role of microorganisms that reside in the human gut has attracted much attention beyond classical infectious diseases. For example, numerous studies have reported changes in the gut microbiota during not only obesity, diabetes, and liver diseases but also cancer and even neurodegenerative diseases. The human gut microbiota is viewed as a potential source of novel therapeutics. Between 2013 and 2017, the number of publications focusing on the gut microbiota was, remarkably, 12 900, which represents four-fifths of the total number of publications over the last 40 years that investigated this topic. This review discusses recent evidence of the impact of the gut microbiota on metabolic disorders and focus on selected key mechanisms. This review also aims to provide a critical analysis of the current knowledge in this field, identify putative key issues or problems and discuss misinterpretations. The abundance of metagenomic data generated on comparing diseased and healthy subjects can lead to the erroneous claim that a bacterium is causally linked with the protection or the onset of a disease. In fact, environmental factors such as dietary habits, drug treatments, intestinal motility and stool frequency and consistency are all factors that influence the composition of the microbiota and should be considered. The cases of the bacteria Prevotella copri and Akkermansia muciniphila will be discussed as key examples.

Intestinal microbiota and the immune system in metabolic diseases

The intestinal microbiota is comprised of millions of microorganisms that reside in the gastrointestinal tract and consistently interact with the host. Host factors such as diet and disease status affect the composition of the microbiota, while the microbiota itself produces metabolites that can further manipulate host physiology. Dysbiosis of the intestinal microbiota has been characterized in patients with certain metabolic diseases, some of which involve damage to the host intestinal epithelial barrier and alterations in the immune system. In this review, we will discuss the consequences of dietdependent bacterial dysbiosis in the gastrointestinal tract, and how the associated interaction with epithelial and immune cells impacts metabolic diseases.

Exposure to cigarette smoke disturbs adipokines secretion causing intercellular damage and insulin resistance in high fructose diet-induced metabolic disorder mice

A large amount of fructose intake along with smoking is associated with increased incidence of diseases linked to metabolic syndrome. More research is necessary to understand the complex mechanism that ultimately results in metabolic syndrome and the effect, if any, of high fructose dietary intake and smoking on individual health. In this study, we investigated changes in ER-Golgi network and disturbance to secretion of adipokines induced by cigarette smoking (CS) and excess fructose intake and their contribution to the disruption of metabolic homeostasis. We used high fructose-induced metabolic disorder mice model by feeding them with high fructose diet for 8 weeks. For CS exposure experiment, these mice were exposed to CS for 28 days according to OECD guideline 412. Our results clearly showed that the immune system was suppressed and ER stress was induced in mice with exposure to CS and fed with high fructose. Furthermore, their concentrations of adipokines including leptin and adiponectin were aberrant. Such alteration in secretion of adipokines could cause insulin resistance which may lead to the development of type 2 diabetes.

Foundations of Immunometabolism and Implications for Metabolic Health and Disease

Highly ordered interactions between immune and metabolic responses are evolutionarily conserved and paramount for tissue and organismal health. Disruption of these interactions underlies the emergence of many pathologies, particularly chronic non-communicable diseases such as obesity and diabetes. Here, we examine decades of research identifying the complex immunometabolic signaling networks and the cellular and molecular events that occur in the setting of altered nutrient and energy exposures and offer a historical perspective. Furthermore, we describe recent advances such as the discovery that a broad complement of immune cells play a role in immunometabolism and the emerging evidence that nutrients and metabolites modulate inflammatory pathways. Lastly, we discuss how this work may eventually lead to tangible therapeutic advancements to promote health.

A Novel Mouse Model of iNKT Cell-deficiency Generated by CRISPR/Cas9 Reveals a Pathogenic Role of iNKT Cells in Metabolic Disease

iNKT cells play important roles in immune regulation by bridging the innate and acquired immune systems. The functions of iNKT cells have been investigated in mice lacking the Traj18 gene segment that were generated by traditional embryonic stem cell technology, but these animals contain a biased T cell receptor (TCR) repertoire that might affect immune responses. To circumvent this confounding factor, we have generated a new strain of iNKT cell-deficient mice by deleting the Traj18 locus using CRISPR/Cas9 technology, and these animals contain an unbiased TCR repertoire. We employed these mice to investigate the contribution of iNKT cells to metabolic disease and found a pathogenic role of these cells in obesity-associated insulin-resistance. The new Traj18-deficient mouse strain will assist in studies of iNKT cell biology.

[Gut microbiota and immune crosstalk in metabolic disease]

The aim of the review is to discuss about the role played by the defence crosstalk between the gut microbiota and the intestinal immune system, in the development of metabolic disease focusing on obesity and diabetes. Starting from physiological and pathological stand points and based on the latest published data, this review is addressing how the concept of the hologenome theory of evolution can drive the fate of metabolic disease. The notion of "metabolic infection" to explain the "metabolic inflammation" is discussed. This imply comments about the process of bacterial translocation and impaired intestinal immune defense against commensals. Eventually this review sets the soil for personalized medicine. The monthly increase in the number of publications on the gut microbiota to intestinal immune defense and the control of metabolism demonstrate the importance of this field of investigation. The notion of commensal as "self or non-self" has to be reevaluated in the light of the current data. Furthermore, data demonstrate the major role played by short chain fatty acids, secondary bile acids, LPS, peptidoglycans, indole derivatives, and other bacteria-related molecules on the shaping of cells involved in the intestinal protection against commensals is now becoming a central player in the incidence of metabolic diseases. The literature demonstrates that the onset of metabolic diseases and some specific co-morbidities can be explained by a gut microbiota to intestinal immune system crosstalk. Therefore, one should now consider this avenue of investigation as a putative source of biomarkers and therapeutic targets to personalize the treatment of metabolic disease and its co-morbidities. Gut microbiota is considered as a major regulator of metabolic disease. This reconciles the notion of metabolic inflammation and the epidemic development of the disease. In addition to evidence showing that a specific gut microbiota characterizes patients with obesity, type 2 diabetes, and hepatic steatosis, the mechanisms causal to the disease could be related to the translocation of microbiota from the gut to the tissues, which induces inflammation. The mechanisms regulating such a process are based on the crosstalk between the gut microbiota and the host immune system. The hologenome theory of evolution supports this concept and implies that therapeutic strategies aiming to control glycemia should take into account both the gut microbiota and the host immune system. This review discusses the latest evidence regarding the bidirectional impact of the gut microbiota on host immune system crosstalk for the control of metabolic disease, hyperglycemia, and obesity. To avoid redundancies with the literature, we will focus our attention on the intestinal immune system, identifying evidence for the generation of novel therapeutic strategies, which could be based on the control of the translocation of gut bacteria to tissues. Such novel strategies should hamper the role played by gut microbiota dysbiosis on the development of metabolic inflammation. Recent evidence in rodents allows us to conclude that an impaired intestinal immune system characterizes and could be causal in the development of metabolic disease. The fine understanding of the molecular mechanisms should allow for the development of a first line of treatment for metabolic disease and its co-morbidities.

Loss of macrophage fatty acid oxidation does not potentiate systemic metabolic dysfunction

Fatty acid oxidation in macrophages has been suggested to play a causative role in high-fat diet-induced metabolic dysfunction, particularly in the etiology of adipose-driven insulin resistance. To understand the contribution of macrophage fatty acid oxidation directly to metabolic dysfunction in high-fat diet-induced obesity, we generated mice with a myeloid-specific knockout of carnitine palmitoyltransferase II (CPT2 Mϕ-KO), an obligate step in mitochondrial long-chain fatty acid oxidation. While fatty acid oxidation was clearly induced upon IL-4 stimulation, fatty acid oxidation-deficient CPT2 Mϕ-KO bone marrow-derived macrophages displayed canonical markers of M2 polarization following IL-4 stimulation in vitro. In addition, loss of macrophage fatty acid oxidation in vivo did not alter the progression of high-fat diet-induced obesity, inflammation, macrophage polarization, oxidative stress, or glucose intolerance. These data suggest that although IL-4-stimulated alternatively activated macrophages upregulate fatty acid oxidation, fatty acid oxidation is dispensable for macrophage polarization and high-fat diet-induced metabolic dysfunction. Macrophage fatty acid oxidation likely plays a correlative, rather than causative, role in systemic metabolic dysfunction.

Comparisons of the Postprandial Inflammatory and Endotoxaemic Responses to Mixed Meals in Young and Older Individuals: A Randomised Trial

Postprandial inflammation and endotoxaemia are determinants of cardiovascular and metabolic disease risk which are amplified by high fat meals. We aimed to examine the determinants of postprandial inflammation and endotoxaemia in older and younger adults following a high fat mixed meal. In a randomised cross-over trial, healthy participants aged 20-25 and 60-75 years (n = 15/group) consumed a high-fat breakfast and a low-fat breakfast. Plasma taken at baseline and post-meal for 5 h was analysed for circulating endotoxin, cytokines (monocyte chemotactic protein-1 (MCP-1), interleukin (IL)-1β, IL-6, and tumour necrosis factor-alpha (TNF-α)), lipopolysaccharide binding protein (LBP), and inflammatory gene expression in peripheral blood mononuclear cells (PBMC). Older subjects had lower baseline PBMC expression of Glutathione peroxidase 1 (GPX-1) but greater insulin-like growth factor-binding protein 3 (IGFBP3) and circulating MCP-1 compared to younger subjects. After either meal, there were no age differences in plasma, chylomicron endotoxin, or plasma LBP concentrations, nor in inflammatory cytokine gene and protein expression (MCP-1, IL-1β, and TNF-α). Unlike younger participants, the older group had decreased superoxide dismutase (SOD)-2 expression after the meals. After a high-fat meal, older adults have no increased inflammatory or endotoxin response, but an altered oxidative stress gene response compared with younger adults. Healthy older adults, without apparent metabolic dysfunction, have a comparable postprandial inflammatory and endotoxaemia response to younger adults.

Gut microbiota interactions with the immunomodulatory role of vitamin D in normal individuals

BACKGROUND

Due to immunomodulatory properties, vitamin D status has been implicated in several diseases beyond the skeletal disorders. There is evidence that its deficiency deteriorates the gut barrier favoring translocation of endotoxins into the circulation and systemic inflammation. Few studies investigated whether the relationship between vitamin D status and metabolic disorders would be mediated by the gut microbiota composition.

OBJECTIVE

We examined the association between vitamin D intake and circulating levels of 25(OH)D with gut microbiota composition, inflammatory markers and biochemical profile in healthy individuals.

METHODS

In this cross-sectional analysis, 150 young healthy adults were stratified into tertiles of intake and concentrations of vitamin D and their clinical and inflammatory profiles were compared. The DESeq2 was used for comparisons of microbiota composition and the log2 fold changes (log2FC) represented the comparison against the reference level. The association between 25(OH)D and fecal microbiota (16S rRNA sequencing, V4 region) was tested by multiple linear regression.

RESULTS

Vitamin D intake was associated with its concentration (r=0.220, p=0.008). There were no significant differences in clinical and inflammatory variables across tertiles of intake. However, lipopolysaccharides increased with the reduction of 25(OH)D (p-trend <0.05). Prevotella was more abundant (log2FC 1.67, p<0.01), while Haemophilus and Veillonella were less abundant (log2FC -2.92 and -1.46, p<0.01, respectively) in the subset with the highest vitamin D intake (reference) than that observed in the other subset (first plus second tertiles). PCR (r=-0.170, p=0.039), E-selectin (r=-0.220, p=0.007) and abundances of Coprococcus (r=-0.215, p=0.008) and Bifdobacterium (r=-0.269, p=0.001) were inversely correlated with 25(OH)D. After adjusting for age, sex, season and BMI, 25(OH)D maintained inversely associated with Coprococcus (β=-9.414, p=0.045) and Bifdobacterium (β=-1.881, p=0.051), but significance disappeared following the addition of inflammatory markers in the regression models.

CONCLUSION

The role of vitamin D in the maintenance of immune homeostasis seems to occur in part by interacting with the gut microbiota. The attenuation of association of bacterial genera by inflammatory markers suggests that inflammation participate in part in the relationship between the gut microbiota and vitamin D concentration. Studies with appropriate design are necessary to address hypothesis raised in the current study.

The Role of the Immune System in Metabolic Health and Disease

In addition to the immune system's traditional roles of conferring anti-infectious and anti-neoplastic protection, it has been recently implicated in the regulation of systemic metabolic homeostasis. This cross-talk between the immune and the metabolic systems is pivotal in promoting "metabolic health" throughout the life of an organism and plays fundamental roles in its adaptation to ever-changing environmental makeups and nutritional availability. Perturbations in this intricate immune-metabolic cross-talk contribute to the tendency to develop altered metabolic states that may culminate in metabolic disorders such as malnutrition, obesity, type 2 diabetes mellitus (T2DM), and other features of the metabolic syndrome. Regulators of immune-metabolic interactions include host genetics, nutritional status, and the intestinal microbiome. In this Perspective, we highlight current understanding of immune-metabolism interactions, illustrate differences among individuals and between populations in this respect, and point toward future avenues of research possibly enabling immune harnessing as means of personalized treatment for common metabolic disorders.

Fatty acid metabolism in macrophages: a target in cardio-metabolic diseases

PURPOSE OF REVIEW

Recent studies have highlighted that macrophages dynamically and autonomously handle all the facets of fatty acid (FA) metabolism including FA oxidation and FA synthesis as well as the synthesis of monounsaturated FAs and long chain n-3 and n-6 polyunsaturated FAs.

RECENT FINDINGS

Macrophage M2 polarization is associated with an increase of FA oxidation. However, whether increased FA oxidation simply correlates with or is required for M2 polarization needs to be further evaluated. Macrophage M1 polarization is associated with the activation of FA synthesis, which directly contributes to the inflammatory response and affects cholesterol homeostasis and neutral lipid accumulation. Finally, recent evidences suggest that macrophages are able to autonomously produce signaling monounsaturated FAs, such as palmitoleic acid (C16 : 1 n-7), and long chain n-3 and n-6 polyunsaturated FAs, such as arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid. This pathway is regulated by liver X receptors and has significant consequences on inflammation and on the FA composition of atheroma plaques.

SUMMARY

These studies shed new light on the tight relationship between FA metabolism, macrophage polarization, and M1/M2 macrophage functions. These processes may have major consequences for atherosclerosis pathogenesis as well as other metabolic disorders.

Tissue Immunometabolism: Development, Physiology, and Pathobiology

Evolution of metazoans resulted in the specialization of cellular and tissue function. This was accomplished by division of labor, which allowed tissue parenchymal cells to prioritize their core functions while ancillary functions were delegated to tissue accessory cells, such as immune, stromal, and endothelial cells. In metabolic organs, the accessory cells communicate with their clients, the tissue parenchymal cells, to optimize cellular processes, allowing organisms to adapt to changes in their environment. Here, we discuss tissue immunometabolism from this vantage point and use examples from adipose tissues (white, beige, and brown) and liver to outline the general principles by which accessory cells support metabolic homeostasis in parenchymal cells. A corollary of this model is that disruption of communication between client and accessory cells might predispose metabolic organs to the development of disease.

The initiation of metabolic inflammation in childhood obesity

An understanding of the events that initiate metabolic inflammation (metainflammation) can support the identification of targets for preventing metabolic disease and its negative effects on health. There is ample evidence demonstrating that the initiating events in obesity-induced inflammation start early in childhood. This has significant implications on our understanding of how early life events in childhood influence adult disease. In this Review we frame the initiating events of metainflammation in the context of child development and discuss what this reveals about the mechanisms by which this unique form of chronic inflammation is initiated and sustained into adulthood.

Function and Dysfunction of Adipose Tissue

Adipose tissue is an endocrine organ which is responsible for postprandial uptake of glucose and fatty acids, consequently producing a broad range of adipokines controlling several physiological functions like appetite, insulin sensitivity and secretion, immunity, coagulation, and vascular tone, among others. Many aspects of adipose tissue pathophysiology in metabolic diseases have been described in the last years. Recent data suggest two main factors for adipose tissue dysfunction: accumulation of nonesterified fatty acids and their secondary products and hypoxia. Both of these factors are thought to be on the basis of low-grade inflammatory activation, further increasing metabolic dysregulation in adipose tissue. In turn, inflammation is involved in the inhibition of substrate uptake, alteration of the secretory profile, stimulation of angiogenesis, and recruitment of further inflammatory cells, which creates an inflammatory feedback in the tissue and is responsible for long-term establishment of insulin resistance.

Regulation of Nlrp3 inflammasome by dietary metabolites

The bidirectional communication between innate immune cells and energy metabolism is now widely appreciated to regulate homeostasis as well as chronic diseases that emerge from dysregulated inflammation. Macronutrients-derived from diet or endogenous pathways that generate and divert metabolites into energetic or biosynthetic pathways – regulate the initiation, duration and cessation of the inflammatory response. The NLRP3 inflammasome is an important innate sensor of structurally diverse metabolic damage-associated molecular patterns (DAMPs) that has been implicated in a wide range of inflammatory disorders associated with caloric excess, adiposity and aging. Understanding the regulators of immune-metabolic interactions and their contribution towards chronic disease mechanisms, therefore, has the potential to reduce disease pathology, improve quality of life in elderly and promote the extension of healthspan. Just as specialized subsets of immune cells dampen inflammation through the production of negative regulatory cytokines; specific immunoregulatory metabolites can deactivate inflammasome-mediated immune activation. Here, we highlight the role of energy substrates, alternative fuels and metabolic DAMPs in the regulation of the NLRP3 inflammasome and discuss potential dietary interventions that may impact sterile inflammatory disease.

Antioxidant Activity of γ-Oryzanol: A Complex Network of Interactions

γ-oryzanol (Orz), a steryl ferulate extracted from rice bran layer, exerts a wide spectrum of biological activities. In addition to its antioxidant activity, Orz is often associated with cholesterol-lowering, anti-inflammatory, anti-cancer and anti-diabetic effects. In recent years, the usefulness of Orz has been studied for the treatment of metabolic diseases, as it acts to ameliorate insulin activity, cholesterol metabolism, and associated chronic inflammation. Previous studies have shown the direct action of Orz when downregulating the expression of genes that encode proteins related to adiposity (CCAAT/enhancer binding proteins (C/EBPs)), inflammatory responses (nuclear factor kappa-B (NF-κB)), and metabolic syndrome (peroxisome proliferator-activated receptors (PPARs)). It is likely that this wide range of beneficial activities results from a complex network of interactions and signals triggered, and/or inhibited by its antioxidant properties. This review focuses on the significance of Orz in metabolic disorders, which feature remarkable oxidative imbalance, such as impaired glucose metabolism, obesity, and inflammation.

Microbial contributions to chronic inflammation and metabolic disease

PURPOSE OF REVIEW

It is long known that immune and metabolic cascades intersect at various cross-points. More recently, the regulatory influence of the microbiota on both of these cascades has emerged. Advances with therapeutic implications for chronic immunologic and metabolic disorders are examined.

RECENT FINDINGS

Disturbances of the microbiota, particularly in early life, may be the proximate environmental risk factor in socioeconomically developed societies for development of chronic immune-allergic and metabolic disorders, including obesity. Antibiotics and dietary factors contribute to this risk. Multiple microbial signalling molecules mediate host-microbe interactions including bacterial metabolites such as short-chain fatty acids, bile salts and others.

SUMMARY

New strategies for manipulating the composition and metabolic activity of the gut microbiota have emerged and offer a realistic prospect of personalized therapeutic options in immune and metabolic diseases.

Safety profile of anakinra in the management of rheumatologic, metabolic and autoinflammatory disorders

Anakinra is a biologic response modifier that competitively antagonises the biologic effects of interleukin-1, the ancestor pleiotropic proinflammatory cytokine produced by numerous cell types, found in excess in the serum, synovial fluid and any involved tissues of patients with many inflammatory diseases. The magnitude of the risk of different infections, including Mycobacterium tuberculosis (Mtb) infection, associated with the large use of anakinra in many rheumatologic, metabolic or autoinflammatory disorders is still unknown. In addition, it is unclear whether this effect is modified by the concomitant use of antirheumatic drugs and corticosteroids. The rates of development of Mtb disease in patients treated with anakinra due to rheumatoid arthritis, systemic autoinflammatory diseases, Schnitzler's syndrome, Behçet's disease, adult-onset Still disease, systemic juvenile idiopathic arthritis, gout and diabetes mellitus have been usually very low. However, clinicians must carefully weigh the benefits of biological drugs against their risks, particularly in patients prone to infections. Additional data are needed to understand whether this risk of Mtb infection and reactivation are representative of a class effect related to biologics or whether anakinra bears specifically an intrinsic lower risk in comparison with other biologic drugs.

Age-associated metabolic dysregulation in bone marrow-derived macrophages stimulated with lipopolysaccharide

Macrophages are major contributors to age-associated inflammation. Metabolic processes such as oxidative phosphorylation, glycolysis and the urea cycle regulate inflammatory responses by macrophages. Metabolic profiles changes with age; therefore, we hypothesized that dysregulation of metabolic processes could contribute to macrophage hyporesponsiveness to LPS. We examined the intracellular metabolome of bone marrow-derived macrophages from young (6-8 wk) and old (18-22 mo) mice following lipopolysaccharide (LPS) stimulation and tolerance. We discovered known and novel metabolites that were associated with the LPS response of macrophages from young mice, which were not inducible in macrophages from old mice. Macrophages from old mice were largely non-responsive towards LPS stimulation, and we did not observe a shift from oxidative phosphorylation to glycolysis. The critical regulatory metabolites succinate, γ-aminobutyric acid, arginine, ornithine and adenosine were increased in LPS-stimulated macrophages from young mice, but not macrophages from old mice. A shift between glycolysis and oxidative phosphorylation was not observed during LPS tolerance in macrophages from either young or old mice. Metabolic bottlenecks may be one of the mechanisms that contribute to the dysregulation of LPS responses with age.

The role of immune cells in metabolism-related liver inflammation and development of non-alcoholic steatohepatitis (NASH)

The low grade inflammatory state present in obesity promotes the progression of Non-Alcoholic Fatty Liver Disease (NAFLD). In Non-Alcoholic Steatohepatitis (NASH), augmented hepatic steatosis is accompanied by aberrant intrahepatic inflammation and exacerbated hepatocellular injury. NASH is an important disorder and can lead to fibrosis, cirrhosis and even neoplasia. The pathology of NASH involves a complex network of mechanisms, including increased infiltration of different subsets of immune cells, such as monocytes, T-lymphocytes and neutrophils, to the liver, as well as activation and in situ expansion of liver resident cells such as Kupffer cells or stellate cells. In this review, we summarize recent advances regarding understanding the role of the various cells of the innate and adaptive immunity in NASH development and progression, and discuss possible future therapeutic options and tools to interfere with disease progression.

The Cellular and Molecular Basis of Translational Immunometabolism

The immune response requires major changes to metabolic processes, and indeed, energy metabolism and functional activation are fully integrated in immune cells to determine their ability to divide, differentiate, and carry out effector functions. Immune cell metabolism has therefore become an attractive target area for therapeutic purposes. A neglected aspect in the translation of immunometabolism is the critical connection between systemic and cellular metabolism. Here, we discuss the importance of understanding and manipulating the integration of systemic and immune cell metabolism through in-depth analysis of immune cell phenotype and function in human metabolic diseases and, in parallel, of the effects of conventional metabolic drugs on immune cell differentiation and function. We examine how the recent identification of selective metabolic programs operating in distinct immune cell subsets and functions has the potential to deliver tools for cell- and function-specific immunometabolic targeting.

The limited storage capacity of gonadal adipose tissue directs the development of metabolic disorders in male C57Bl/6J mice

AIMS/HYPOTHESIS

White adipose tissue (WAT) consists of various depots with different adipocyte functionality and immune cell composition. Knowledge of WAT-depot-specific differences in expandability and immune cell influx during the development of obesity is limited, therefore we aimed to characterise different WAT depots during the development of obesity in mice.

METHODS

Gonadal WAT (gWAT), subcutaneous WAT (sWAT) and mesenteric WAT (mWAT) were isolated from male C57Bl/6J mice with different body weights (approximately 25-60 g) and analysed. Linear and non-linear regression models were used to describe the extent of WAT depot expandability and immune cell composition as a function of body weight.

RESULTS

Whereas mouse sWAT and mWAT continued to expand with body weight, gWAT expanded mainly during the initial phase of body weight gain. The expansion diminished after the mice reached a body weight of around 40 g. From this point on, gWAT crown-like structure formation, liver steatosis and insulin resistance occurred. Mouse WAT depots showed major differences in immune cell composition: gWAT consisted mainly of macrophages, whereas sWAT and mWAT primarily contained lymphocytes.

CONCLUSIONS/INTERPRETATION

Marked inter-depot differences exist in WAT immune cell composition and expandability. The limited storage capacity of gWAT seems to direct the development of metabolic disorders in male C57Bl/6J mice.

Oral Infections, Metabolic Inflammation, Genetics, and Cardiometabolic Diseases

Although several epidemiologic studies reported plausible and potentially causal associations between oral infections and cardiometabolic diseases (CMDs), controversy still lingers. This might be due to unrecognized confounding from metabolic inflammation and genetics, both of which alter the immune responses of the host. Low-grade inflammation termed metainflammation is the hallmark of obesity, insulin resistance, type 2 diabetes, and CMDs. According to the common soil theory, the continuum of obesity to CMDs is the same pathology at different time points, and early metainflammations, such as hyperglycemia and obesity, display many adverse cardiometabolic characteristics. Consequently, adipose tissue is now considered a dynamic endocrine organ that expresses many proinflammatory cytokines such as TNF-α, IL-6, plasminogen activator inhibitor 1, and IL-1β. In metainflammation, IL-1β and reactive oxygen species are generated, and IL-1β is a pivotal molecule in the pathogenesis of CMDs. Note that the same cytokines expressed in metainflammation are also reported in oral infections. In metabolic inflammation and oral infections, the innate immune system is activated through pattern recognition receptors-which include transmembrane receptors such as toll-like receptors (TLRs), cytosolic receptors such as nucleotide-binding oligomerization domain-like receptors, and multiprotein complexes called inflammasome. In general, TLR-2s are presumed to recognize lipoteichoic acid of Gram-positive microbes-and TLR-4s, lipopolysaccharide of Gram-negative microbes-while nucleotide-binding oligomerization domain-like receptors detect both Gram-positive and Gram-negative peptidoglycans on the bacterial cell walls. However, a high-fat diet activates TLR-2s, and obesity activates TLR-4s and induces spontaneous increases in serum lipopolysaccharide levels (metabolic endotoxemia). Moreover, genetics controls lipid-related transcriptome and the differentiation of monocyte and macrophages. Additionally, genetics influences CMDs, and this creates a confounding relationship among oral infections, metainflammation, and genetics. Therefore, future studies must elucidate whether oral infections can increase the risk of CMDs independent of the aforementioned confounding factors.

Lymphocyte roles in metabolic dysfunction: of men and mice

Type 2 diabetes (T2D) is a metabolic disease associated with obesity-related insulin resistance (IR) and chronic inflammation. Animal studies indicate that IR can be caused and/or exacerbated by systemic and/or tissue-specific alterations in lymphocyte differentiation and function. Human studies also indicate that obesity-associated inflammation promotes IR. Nevertheless, clinical trials with anti-inflammatory therapies have yielded modest impacts on established T2D. Unlike mouse models, where obesity is predominantly associated with IR, 20-25% of obese humans are metabolically healthy with high insulin sensitivity. The uncoupling of obesity from IR in humans but not in animal models advocates for a more comprehensive understanding of mediators and mechanisms of human obesity-promoted IR, and better integration of knowledge from human studies into animal experiments to efficiently pursue T2D prevention and treatment.

Cardiovascular and metabolic risk factors in inherited autoinflammation

CONTEXT

The natural progression of metabolic abnormalities among patients with inherited autoinflammation is unclear.

OBJECTIVE

The objective of the study was to assess the cardiometabolic risk of participants with familial Mediterranean fever (FMF).

DESIGN AND SETTING

This study included nationwide cross-sectional and longitudinal cohorts.

PARTICIPANTS

The prevalence of components of the metabolic syndrome at age 17 years was assessed from the medical database of the Israeli Defense Force from 1973 through 1997. Included were 745 males with FMF, 902 healthy male siblings, and a control group of 787,714 participants. A prospective follow-up study traced the incidence of components of the metabolic syndrome to age 45 years among 57 FMF and 1568 control army personnel participants.

INTERVENTIONS

Body mass index (BMI) and blood pressure (BP) were measured at age 17 years (cross-sectional); lifestyle, anthropometric, and biochemical data were periodically recorded from age 25 years.

MAIN OUTCOME MEASURES

Abnormal BMI or BP (age 17 y) and Adult Treatment Panel III criteria of the metabolic syndrome were measured.

RESULTS

In multivariable regression analysis adjusted for known confounders of obesity, FMF participants had an odds ratio of 0.65 for the occurrence of overweight [95% confidence interval (CI) 0.44-0.96, P = .03] and 0.66 (95% CI 0.48-0.92, P = .012) for hypertension-range BP; their siblings tended to obesity (odds ratio 1.48; 95% CI 1.04-2.11, P = .008). In the follow-up arm, a multivariable analysis adjusted for age, birth year, BMI, education, socioeconomic status, ethnicity, and physical activity yielded hazard ratios of 0.32 (95% CI 0.10-0.82, P = .002) for incident obesity, 0.49 (95% CI 0.25-0.95, P = .037) for incident triglycerides 150 mg/dL or greater, 0.56 (95% CI 0.31-0.98, P = .048) for low-density lipoprotein cholesterol 130 mg/dL or greater, and 2.14 (1.368-3.359, P = .001) for high-density lipoprotein cholesterol less than 40 mg/dL for FMF participants compared with controls. Incident elevated BP was lower among FMF participants (hazard ratio 0.49; 95% CI 0.23-1.00, P = .05), whereas dysglycemia incidence was comparable.

CONCLUSIONS

FMF is associated with lower rates of most components of the metabolic syndrome compared with normal subjects, unlike other inflammatory conditions.

Central obesity as a clinical marker of adiposopathy; increased visceral adiposity as a surrogate marker for global fat dysfunction

PURPOSE OF REVIEW

Subcutaneous adipose tissue (SAT) is often described as 'protective'. Visceral adipose tissue (VAT) is often described as 'pathologic'. However, both SAT and VAT have protective and pathologic potential, with interdependent biologic functions.

RECENT FINDINGS

Most of the body's (excess) energy is stored as fat in SAT. If during positive caloric balance, SAT does not undergo adequate adipogenesis, then excess energy may result in adipocyte hypertrophy, leading to hypoxia, immunopathies, and endocrinopathies. Energy overflow may promote accumulation of pericardial fat, perivascular fat, and myocardial fat, which may directly contribute to atherosclerotic cardiovascular disease (CVD). Lipotoxic free fatty acid delivery to nonadipose body organs (e.g. liver, muscle, and pancreas) may indirectly contribute to CVD by promoting the most common metabolic disorders encountered in clinical practice (e.g. high blood sugars, high blood pressure, and dyslipidaemia), all major CVD risk factors. Finally, SAT energy overflow may increase VAT accumulation, which is also associated with increased risk of metabolic diseases and CVD.

SUMMARY

Increased VAT is a surrogate marker for SAT dysfunction which increases waist circumference, reflecting a shared pathologic process leading to the pathogenic fat accumulation of other fat depots and fatty infiltration of nonadipose body organs. Central obesity is a clinical marker for adiposopathy.