Energetic Trade-Offs and Hypometabolic States Promote Disease Tolerance.

Host defenses against pathogens are energetically expensive, leading ecological immunologists to postulate that they might participate in energetic trade-offs with other maintenance programs. However, the metabolic costs of immunity and the nature of physiologic trade-offs it engages are largely unknown. We report here that activation of immunity causes an energetic trade-off with the homeothermy (the stable maintenance of core temperature), resulting in hypometabolism and hypothermia. This immunity-induced physiologic trade-off was independent of sickness behaviors but required hematopoietic sensing of lipopolysaccharide (LPS) via the toll-like receptor 4 (TLR4). Metabolomics and genome-wide expression profiling revealed that distinct metabolic programs supported entry and recovery from the energy-conserving hypometabolic state. During bacterial infections, hypometabolic states, which could be elicited by competition for energy between maintenance programs or energy restriction, promoted disease tolerance. Together, our findings suggest that energy-conserving hypometabolic states, such as dormancy, might have evolved as a mechanism of tissue tolerance.

Selenoproteins as regulators of T cell proliferation, differentiation, and metabolism.

Selenium (Se) is an essential micronutrient that plays a key role in regulating the immune system. T cells are of particular interest due to their important role in promoting adaptive immunity against pathogens and cancer as well as regulating tolerance, all of which are influenced by dietary Se levels. The biological effects of Se are mainly exerted through the actions of the proteins into which it is inserted, i.e. selenoproteins. Thus, the roles that selenoproteins play in regulating T cell biology and molecular mechanisms involved have emerged as important areas of research for understanding how selenium affects immunity. Members of this diverse family of proteins exhibit a wide variety of functions within T cells that include regulating calcium flux induced by T cell receptor (TCR) engagement, shaping the redox tone of T cells before, during, and after activation, and linking TCR-induced activation to metabolic reprogramming required for T cell proliferation and differentiation. This review summarizes recent insights into the roles that selenoproteins play in these processes and their implications in understanding how Se may influence immunity.

Metabolic labeling of HIV-1 envelope glycoprotein gp120 to elucidate the effect of gp120 glycosylation on antigen uptake.

The glycan shield on the envelope glycoprotein gp120 of HIV-1 has drawn immense attention as a vulnerable site for broadly neutralizing antibodies and for its significant impact on host adaptive immune response to HIV-1. Glycosylation sites and glycan composition/structure at each site on gp120 along with the interactions of gp120 glycan shield with broadly neutralizing antibodies have been extensively studied. However, a method for directly and selectively tracking gp120 glycans has been lacking. Here, we integrate metabolic labeling and click chemistry technology with recombinant gp120 expression to demonstrate that gp120 glycans could be specifically labeled and directly detected. Selective labeling of gp120 by N-azidoacetylmannosamine (ManNAz) and N-azidoacetylgalactosamine (GalNAz) incorporation into the gp120 glycan shield was characterized by MS of tryptic glycopeptides. By using metabolically labeled gp120, we investigated the impact of gp120 glycosylation on its interaction with host cells and demonstrated that oligomannose enrichment and sialic acid deficiency drastically enhanced gp120 uptake by bone marrow-derived dendritic cells. Collectively, our data reveal an effective labeling and detection method for gp120, serving as a tool for functional characterization of the gp120 glycans and potentially other glycosylated proteins.

The Interplay of Lipids, Lipoproteins, and Immunity in Atherosclerosis.

PURPOSE OF REVIEW: Atherosclerosis is an inflammatory disorder of the arterial wall, in which several players contribute to the onset and progression of the disease. Besides the well-established role of lipids, specifically cholesterol, and immune cell activation, new insights on the molecular mechanisms underlying the atherogenic process have emerged. RECENT FINDINGS: Meta-inflammation, a condition of low-grade immune response caused by metabolic dysregulation, immunological memory of innate immune cells (referred to as "trained immunity"), cholesterol homeostasis in dendritic cells, and immunometabolism, i.e., the interplay between immunological and metabolic processes, have all emerged as new actors during atherogenesis. These observations reinforced the interest in directly targeting inflammation to reduce cardiovascular disease. The novel acquisitions in pathophysiology of atherosclerosis reinforce the tight link between lipids, inflammation, and immune response, and support the benefit of targeting LDL-C as well as inflammation to decrease the CVD burden. How this will translate into the clinic will depend on the balance between costs (monoclonal antibodies either to PCSK9 or to IL-1ß), side effects (increased incidence of death due to infections for anti-IL-1ß antibody), and the benefits for patients at high CVD risk.

Immunometabolism and autoimmunity.

A continuous increase in the prevalence of autoimmune diseases is to be expected in the aging societies worldwide. Autoimmune disorders not only cause severe disability and chronic pain, but also lead to considerable socio-economic costs. Given that the current treatment options are not curative, have substantial side effects and a high percentage of non-responders, innovative options to the existing therapeutic armament against autoimmune diseases are urgently required. Accumulating evidence suggests that changes in the metabolism of immune cells are associated with, and contribute to the pathogenesis of autoimmunity. Additionally, some autoimmune diseases share alterations in metabolic pathways, key metabolites or metabolic byproducts such as reactive oxygen species. Other examples for metabolic changes in autoimmune settings include modifications in amino acid and cholesterol levels or glucose catabolism. Thus, the emerging field of immunometabolism may hold the potential to discover new therapeutic targets. Here, we discuss recent findings describing metabolic changes in autoimmune arthritis, multiple sclerosis as well as type 1 diabetes, focusing on pathophysiological aspects.

From cytokine to myokine: the emerging role of interleukin-6 in metabolic regulation.

The lack of physical activity and overnutrition in our modern lifestyle culminates in what we now experience as the current obesity and diabetes pandemic. Medical research performed over the past 20 years identified chronic low-grade inflammation as a mediator of these metabolic disorders. Hence, finding therapeutic strategies against this underlying inflammation and identifying molecules implicated in this process is of significant importance. Following the observation of an increased plasma concentration of interleukin-6 (IL-6) in obese patients, this protein, known predominantly as a pro-inflammatory cytokine, came into focus. In an attempt to clarify its importance, several studies implicated IL-6 as a co-inducer of the development of obesity-associated insulin resistance, which precedes the development of type 2 diabetes. However, the identification of IL-6 as a myokine, a protein produced and secreted by skeletal muscle to fulfil paracrine or endocrine roles in the insulin-sensitizing effects following exercise, provides a contrasting and hence paradoxical identity of this protein in the context of metabolism. We review here the literature considering the complex, pleiotropic role of IL-6 in the context of metabolism in health and disease.

EMBO workshop on immunology and metabolism.

Recent findings have identified roles for the immune system in what were previously considered to be prototypic metabolic diseases, and metabolic control has emerged as an important determinant of immune function. Giovanna Chimini, Lee Leserman, Diane Mathis and Philippe Naquet organized the EMBO Workshop on Immunology & Metabolism, which took place in January 2011 at the Centre d'Immunologie de Marseille-Luminy (CIML) in Marseille, France. The meeting brought together approximately 100 scientists to discuss interactions between metabolism and inflammation.

Immunometabolism of Tissue-Resident Macrophages - An Appraisal of the Current Knowledge and Cutting-Edge Methods and Technologies.

Tissue-resident macrophages exist in unique environments, or niches, that inform their identity and function. There is an emerging body of literature suggesting that the qualities of this environment, such as the types of cells and debris they eat, the intercellular interactions they form, and the length of time spent in residence, collectively what we call habitare, directly inform their metabolic state. In turn, a tissue-resident macrophage's metabolic state can inform their function, including whether they resolve inflammation and protect the host from excessive perturbations of homeostasis. In this review, we summarize recent work that seeks to understand the metabolic requirements for tissue-resident macrophage identity and maintenance, for how they respond to inflammatory challenges, and for how they perform homeostatic functions or resolve inflammatory insults. We end with a discussion of the emerging technologies that are enabling, or will enable, in situ study of tissue-resident macrophage metabolism.

Catabolic cytokine expressions in patients with degenerative disc disease.

AIM: Lumbar degenerative disc disease (DDD) is a common disease of advanced age characterized by progressive changes in the intervertebral disc and associated structures. There have been great efforts for years to explain its pathophysiological mechanism(s). This study aims to provide cytokine profile and in addition to the lymphocytes in a population of patients with lumbar DDD. MATERIAL AND METHODS: Twenty-six patients whose clinical and radiological features were suggestive of lumbar DDD that underwent surgery and 14 autopsy cases as control were included. Patient disc samples were obtained during surgery whilst disc materials were collected during autopsy procedures from the controls. Major cytokines and lymphocytes were studied by using the flow cytometry method. RESULTS: Significantly higher levels in disc samples in relation to IL-1ß, IL-2, IL-4, IL-10, IL-12, TNF-α, CD8, CD56, CD19, and CD40 were found in the patients compared to the controls. Positive correlations were shown between CD3/CD4, CD25/CD3, CD25/CD4, CD19/CD4 but negative correlations were shown between CD19/CD3 and CD25/CD19 in both groups. CONCLUSION: The findings suggest that both local inflammatory responses occur in lumbar DDD. Using specific cytokines either by local or systemic application may reverse the degenerative process.

Immune control by amino acid catabolism during tumorigenesis and therapy.

Immune checkpoints arise from physiological changes during tumorigenesis that reprogramme inflammatory, immunological and metabolic processes in malignant lesions and local lymphoid tissues, which constitute the immunological tumour microenvironment (TME). Improving clinical responses to immune checkpoint blockade will require deeper understanding of factors that impact local immune balance in the TME. Elevated catabolism of the amino acids tryptophan (Trp) and arginine (Arg) is a common TME hallmark at clinical presentation of cancer. Cells catabolizing Trp and Arg suppress effector T cells and stabilize regulatory T cells to suppress immunity in chronic inflammatory diseases of clinical importance, including cancers. Processes that induce Trp and Arg catabolism in the TME remain incompletely defined. Indoleamine 2,3 dioxygenase (IDO) and arginase 1 (ARG1), which catabolize Trp and Arg, respectively, respond to inflammatory cues including interferons and transforming growth factor-ß (TGFß) cytokines. Dying cells generate inflammatory signals including DNA, which is sensed to stimulate the production of type I interferons via the stimulator of interferon genes (STING) adaptor. Thus, dying cells help establish local conditions that suppress antitumour immunity to promote tumorigenesis. Here, we review evidence that Trp and Arg catabolism contributes to inflammatory processes that promote tumorigenesis, impede immune responses to therapy and might promote neurological comorbidities associated with cancer.

Immunometabolism at the interface between macrophages and pathogens.

It is generally regarded that the progression of an infection within host macrophages is the consequence of a failed immune response. However, recent appreciation of macrophage heterogeneity, with respect to both development and metabolism, indicates that the reality is more complex. Different lineages of tissue-resident macrophages respond divergently to microbial, environmental and immunological stimuli. The emerging picture that the developmental origin of macrophages determines their responses to immune stimulation and to infection stresses the importance of in vivo infection models. Recent investigations into the metabolism of infecting microorganisms and host macrophages indicate that their metabolic interface can be a major determinant of pathogen growth or containment. This Review focuses on the integration of data from existing studies, the identification of challenges in generating and interpreting data from ongoing studies and a discussion of the technologies and tools that are required to best address future questions in the field.

Endocannabinoid Catabolic Enzymes Play Differential Roles in Thermal Homeostasis in Response to Environmental or Immune Challenge.

Cannabinoid receptor agonists, such as Δ(9)-THC, the primary active constituent of Cannabis sativa, have anti-pyrogenic effects in a variety of assays. Recently, attention has turned to the endogenous cannabinoid system and how endocannabinoids, including 2-arachidonoylglycerol (2-AG) and anandamide, regulate multiple homeostatic processes, including thermoregulation. Inhibiting endocannabinoid catabolic enzymes, monoacylglycerol lipase (MAGL) or fatty acid amide hydrolase (FAAH), elevates levels of 2-AG or anandamide in vivo, respectively. The purpose of this experiment was to test the hypothesis that endocannabinoid catabolic enzymes function to maintain thermal homeostasis in response to hypothermic challenge. In separate experiments, male C57BL/6J mice were administered a MAGL or FAAH inhibitor, and then challenged with the bacterial endotoxin lipopolysaccharide (LPS; 2 mg/kg ip) or a cold (4 °C) ambient environment. Systemic LPS administration caused a significant decrease in core body temperature after 6 h, and this hypothermia persisted for at least 12 h. Similarly, cold environment induced mild hypothermia that resolved within 30 min. JZL184 exacerbated hypothermia induced by either LPS or cold challenge, both of which effects were blocked by rimonabant, but not SR144528, indicating a CB1 cannabinoid receptor mechanism of action. In contrast, the FAAH inhibitor, PF-3845, had no effect on either LPS-induced or cold-induced hypothermia. These data indicate that unlike direct acting cannabinoid receptor agonists, which elicit profound hypothermic responses on their own, neither MAGL nor FAAH inhibitors affect normal body temperature. However, these endocannabinoid catabolic enzymes play distinct roles in thermoregulation following hypothermic challenges.

Adipose tissue-resident immune cells: key players in immunometabolism.

Adipose tissue (AT) plays a pivotal role in whole-body lipid and glucose homeostasis. AT exerts metabolic control through various immunological mechanisms that instigated a new research field termed immunometabolism. Here, we review AT-resident immune cells and their role as key players in immunometabolism. In lean subjects, AT-resident immune cells have housekeeping functions ranging from apoptotic cell clearance to extracellular matrix remodeling and angiogenesis. However, obesity provides bacterial and metabolic danger signals that mimic bacterial infection, and drives a shift in immune-cell phenotypes and numbers, classified as a prototypic T helper 1 (Th1) inflammatory response. The resulting AT inflammation and insulin resistance link obesity to its metabolic sequel, and suggests that targeted immunomodulatory interventions may be beneficial for obese patients.

At the crossroad between immunity and metabolism: focus on leptin.

White adipose tissue is currently considered to be an active endocrine organ that secretes a plethora of factors named adipokines, most of them proinflammatory in nature, which probably contribute to low-level systemic inflammation; a state that is often present in metabolic syndrome-associated chronic pathologies such as obesity and atherosclerosis. Leptin is historically and indisputably one of the most important adipokines secreted by fat cells, with a variety of physiological roles related to the control of metabolism, energy homeostasis and inflammatory response. One of these functions is the connection between nutritional status and immune competence. Indeed, leptin has been shown to modulate both the innate and adaptive immune responses in both normal and pathological conditions. It has been shown that conditions characterized by low leptin levels are associated with increased susceptibility to infection. Conversely, immune-mediated disorders, such as autoimmune diseases, are associated with increased secretion of leptin and the production of proinflammatory pathogenic cytokines. Thus, leptin can easily be considered a frank mediator of the inflammatory/immune response.

Metabolismo energético, proteico e mineral de ovelhas Santa Inês hígidas e com mastite subclínica / Energy, protein and mineral metabolism in Santa Inês ewes, both healthy and with subclinical mastitis

Este estudo teve por objetivo avaliar o metabolismo energético, proteico e mineral de ovelhas Santa Inês hígidas e com mastite subclínica acompanhadas durante o final da gestação e na lactação. Foram acompanhadas ovelhas submetidas ao mesmo sistema de criação semi-intensivo. Os animais foram avaliados conforme os momentos a seguir: 10 dias que precedeu o parto (dap) e 15 dias pós parto (dpp), 30 dpp, 60 dpp e 90 dpp. Os metabólitos sanguíneos foram avaliados a partir do momento que antecedeu ao parto e os metabólitos no soro lácteo nos momentos subsequentes. Após exame clínico e bacteriológico foi realizada a triagem das ovelhas acompanhadas neste estudo, sendo 12 hígidas e 18 com mastite subclínica. Durante a lactação, mantendo os mesmos critérios de triagem, foram selecionadas 11 glândulas mamárias sadias e 20 infectadas, das quais foi colhido o leite para obtenção do soro lácteo. Foram mensurados no soro sanguíneo os metabólitos do perfil energético (ácidos graxos não esterificados (AGNEs), β-hidroxibutirato (BHB), frutosamina, colesterol e triglicérides), do perfil proteico (proteína total, albumina, uréia e creatinina) e do perfil mineral (ferro, cobre, zinco, magnésio, cálcio total, cálcio ionizado, sódio e potássio). No soro lácteo foram mensurados os íons cálcio, sódio e potássio, bem como os AGNEs e o BHB. A bioquímica sanguínea revelou haver influência (P<0,05) do período do periparto e da lactação sobre as concentrações sanguíneas dos AGNEs, BHB, colesterol, albumina, uréia, cálcio ionizado e no soro lácteo sobre o íon potássio. As ovelhas portadoras de mastite subclínica apresentaram valores sanguíneos superiores (P<0,05) de colesterol, albumina e cobre e no soro lácteo teores superiores do íon sódio e dos AGNEs e inferiores do íon potássio. O bom escore corporal das ovelhas observado durante o estudo aliado aos achados bioquímicos permitiu concluir ter ocorrido maior requerimento energético no primeiro mês da lactação, porém não o suficiente para desencadear qualquer transtorno metabólico e o aparecimento de um quadro de cetonemia, sendo estas discretas alterações mais expressivas nas ovelhas com mastite subclínica.

The study aimed to evaluate the energy, protein and mineral metabolism in Santa Inês ewes, healthy and with subclinical mastitis, followed up during late gestation and lactation periods. Ewes subjected to the same semi-intensive nursing system were followed up. The animals were evaluated according to the following stages: 10 days before parturition (dbp) and 15 days postpartum (dpp), 30 dpp, 60 dpp, and 90 dpp. Blood metabolites were evaluated starting from the stage previous to parturition and whey metabolites were evaluated in the subsequent stages. A screening of the ewes followed up in this study (12 healthy and 18 with subclinical mastitis) was performed after a clinical and bacteriological examination. During lactation, maintaining the same screening criteria, 11 healthy and 20 infected mammary glands were selected; the milk for whey extraction was collected from these glands. Energy profile metabolites (non-esterified fatty acids [NEFAs], β-hydroxybutyrate [BHB], fructosamine, cholesterol and triglycerides), protein profile (total protein, albumin, urea and creatinine) and mineral profile (iron, copper, zinc, magnesium, total calcium, ionized calcium, sodium, and potassium) were measured in the blood serum. Calcium, sodium and potassium ions, as well as NEFAs and BHB were measured in the whey. Blood biochemistry revealed an influence (P<0.05) of the peripartum and lactation periods on the blood concentrations of NEFAs, BHB, cholesterol, albumin, urea, ionized calcium. An analysis of the whey also revealed an influence on the potassium ion. Ewes with subclinical mastitis showed higher (P<0.05) blood levels of cholesterol, albumin and copper; higher sodium ion concentrations and NEFAs, and lower potassium ion in whey. Good physical score of ewes observed during this study, combined with the biochemical findings, allowed us to conclude that there was a larger energy requirement in the first month of lactation; however, this requirement was not enough to trigger any metabolic disorder or the emergence of ketonemia, and these discrete changes were more apparent in ewes with subclinical mastitis.

Hormonoterapia en nutrición

Cuando el aporte de sustratos energéticos no es suficiente para frenar el catabolismo, el paso siguiente es intervenir de forma activaen el espectro neuroendocrino que regula el balance anabolismo-catabolismo. En este trabajo se revisa la respuesta endocrina al estrés y sus implicaciones en el metabolismo proteínico, para evaluar las diferentes posibilidades terapéuticas