scholarly journals GABA transporter sustains IL-1β production in macrophages

2021 ◽  
Vol 7 (15) ◽  
pp. eabe9274
Author(s):  
Yaoyao Xia ◽  
Fang He ◽  
Xiaoyan Wu ◽  
Bie Tan ◽  
Siyuan Chen ◽  
...  
Keyword(s):  
Immune Responses ◽  
High Fat Diet ◽  
Inflammatory Responses ◽  
Innate Immune ◽  
Innate Immune Cells ◽  
High Fat ◽  
Gaba Transporter ◽  
Host Immune Responses ◽  
Diet Induced Obesity

Accumulating evidence shows that nervous system governs host immune responses; however, how γ-aminobutyric acid (GABA)ergic system shapes the function of innate immune cells is poorly defined. Here, we demonstrate that GABA transporter (GAT2) modulates the macrophage function. GAT2 deficiency lowers the production of interleukin-1β (IL-1β) in proinflammatory macrophages. Mechanistically, GAT2 deficiency boosts the betaine/S-adenosylmethionine (SAM)/hypoxanthine metabolic pathway to inhibit transcription factor KID3 expression through the increased DNA methylation in its promoter region. KID3 regulates oxidative phosphorylation (OXPHOS) via targeting the expression of OXPHOS-related genes and is also critical for NLRP3–ASC–caspase-1 complex formation. Likewise, GAT2 deficiency attenuates macrophage-mediated inflammatory responses in vivo, including lipopolysaccharide-induced sepsis, infection-induced pneumonia, and high-fat diet-induced obesity. Together, we propose that targeting GABAergic system (e.g., GABA transporter) could provide previously unidentified therapeutic opportunities for the macrophage-associated diseases.

scholarly journals Differences in Hematopoietic Stem Cells Contribute to Sexually Dimorphic Inflammatory Responses to High Fat Diet-induced Obesity

2015 ◽  
Vol 290 (21) ◽  
pp. 13250-13262 ◽  
Author(s):  
Kanakadurga Singer ◽  
Nidhi Maley ◽  
Taleen Mergian ◽  
Jennifer DelProposto ◽  
Kae Won Cho ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
High Fat Diet ◽  
Inflammatory Responses ◽  
Sexually Dimorphic ◽  
High Fat ◽  
Hematopoietic Stem ◽  
Diet Induced Obesity

scholarly journals CTRP9 transgenic mice are protected from diet-induced obesity and metabolic dysfunction

2013 ◽  
Vol 305 (5) ◽  
pp. R522-R533 ◽  
Author(s):  
Jonathan M. Peterson ◽  
Zhikui Wei ◽  
Marcus M. Seldin ◽  
Mardi S. Byerly ◽  
Susan Aja ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Adipose Tissue ◽  
Transgenic Mice ◽  
High Fat Diet ◽  
Fat Oxidation ◽  
Acid Oxidation ◽  
Ampk Activation ◽  
High Fat ◽  
Diet Induced Obesity

CTRP9 is a secreted multimeric protein of the C1q family and the closest paralog of the insulin-sensitizing adipokine, adiponectin. The metabolic function of this adipose tissue-derived plasma protein remains largely unknown. Here, we show that the circulating levels of CTRP9 are downregulated in diet-induced obese mice and upregulated upon refeeding. Overexpressing CTRP9 resulted in lean mice that dramatically resisted weight gain induced by a high-fat diet, largely through decreased food intake and increased basal metabolism. Enhanced fat oxidation in CTRP9 transgenic mice resulted from increases in skeletal muscle mitochondrial content, expression of enzymes involved in fatty acid oxidation (LCAD and MCAD), and chronic AMPK activation. Hepatic and skeletal muscle triglyceride levels were substantially decreased in transgenic mice. Consequently, CTRP9 transgenic mice had a greatly improved metabolic profile with markedly reduced fasting insulin and glucose levels. The high-fat diet-induced obesity, insulin resistance, and hepatic steatosis observed in wild-type mice were prevented in transgenic mice. Consistent with the in vivo data, recombinant protein significantly enhanced fat oxidation in L6 myotubes via AMPK activation and reduced lipid accumulation in H4IIE hepatocytes. Collectively, these data establish CTRP9 as a novel metabolic regulator and a new component of the metabolic network that links adipose tissue to lipid metabolism in skeletal muscle and liver.

scholarly journals Diet-induced obesity leads to the development of leptin resistance in vagal afferent neurons

2011 ◽  
Vol 301 (1) ◽  
pp. E187-E195 ◽  
Author(s):  
Guillaume de Lartigue ◽  
Claire Barbier de la Serre ◽  
Elvis Espero ◽  
Jennifer Lee ◽  
Helen E. Raybould
Keyword(s):  
High Fat Diet ◽  
Leptin Resistance ◽  
Afferent Neurons ◽  
High Fat ◽  
Leptin Signaling ◽  
Protein Levels ◽  
Diet Induced Obesity ◽  
Nodose Ganglia ◽  
Vagal Afferent

Ingestion of high-fat, high-calorie diets is associated with hyperphagia, increased body fat, and obesity. The mechanisms responsible are currently unclear; however, altered leptin signaling may be an important factor. Vagal afferent neurons (VAN) integrate signals from the gut in response to ingestion of nutrients and express leptin receptors. Therefore, we tested the hypothesis that leptin resistance occurs in VAN in response to a high-fat diet. Sprague-Dawley rats, which exhibit a bimodal distribution of body weight gain, were used after ingestion of a high-fat diet for 8 wk. Body weight, food intake, and plasma leptin levels were measured. Leptin signaling was determined by immunohistochemical localization of phosphorylated STAT3 (pSTAT3) in cultured VAN and by quantifaction of pSTAT3 protein levels by Western blot analysis in nodose ganglia and arcuate nucleus in vivo. To determine the mechanism of leptin resistance in nodose ganglia, cultured VAN were stimulated with leptin alone or with lipopolysaccharide (LPS) and SOCS-3 expression measured. SOCS-3 protein levels in VAN were measured by Western blot following leptin administration in vivo. Leptin resulted in appearance of pSTAT3 in VAN of low-fat-fed rats and rats resistant to diet-induced obesity but not diet-induced obese (DIO) rats. However, leptin signaling was normal in arcuate neurons. SOCS-3 expression was increased in VAN of DIO rats. In cultured VAN, LPS increased SOCS-3 expression and inhibited leptin-induced pSTAT3 in vivo. We conclude that VAN of diet-induced obese rats become leptin resistant; LPS and SOCS-3 may play a role in the development of leptin resistance.

Amyrins from Protium heptaphyllum Reduce High-Fat Diet-Induced Obesity in Mice via Modulation of Enzymatic, Hormonal And Inflammatory Responses

Planta Medica ◽  
2016 ◽  
Vol 83 (03/04) ◽  
pp. 285-291 ◽  
Author(s):  
Karine Carvalho ◽  
Tiago de Melo ◽  
Karina de Melo ◽  
Ana Quinderé ◽  
Francisca de Oliveira ◽  
...  
Keyword(s):  
High Fat Diet ◽  
Inflammatory Responses ◽  
High Fat ◽  
Diet Induced Obesity ◽  
Obesity In Mice

scholarly journals TLR9-mediated inflammation drives a Ccr2-independent peripheral monocytosis through enhanced extramedullary monocytopoiesis

2016 ◽  
Vol 113 (39) ◽  
pp. 10944-10949 ◽  
Author(s):  
Lehn K. Weaver ◽  
Niansheng Chu ◽  
Edward M. Behrens
Keyword(s):  
Autoimmune Diseases ◽  
Inflammatory Responses ◽  
Innate Immune ◽  
Innate Immune Cells ◽  
Wild Type ◽  
Persistent Inflammation ◽  
The Face ◽  
Independent Expansion ◽  
Responsive Cell

Monocytes are innate immune cells that interact with their environment through the expression of pattern recognition receptors, including Toll-like receptors (TLRs). Both monocytes and TLRs are implicated in driving persistent inflammation in autoimmune diseases. However, cell-intrinsic mechanisms to control inflammation, including TLR tolerance, are thought to limit inflammatory responses in the face of repeated TLR activation, leaving it unclear how chronic TLR-mediated inflammation is maintained in vivo. Herein, we used a well-characterized model of systemic inflammation to determine the mechanisms allowing sustained TLR9 responses to develop in vivo. Monocytes were identified as the main TLR9-responsive cell and accumulated in peripherally inflamed tissues during TLR9-driven inflammation. Intriguingly, canonical mechanisms controlling monocyte production and localization were altered during the systemic inflammatory response, as accumulation of monocytes in the liver and spleen developed in the absence of dramatic increases in bone marrow monocyte progenitors and was independent of chemokine (C-C motif) receptor 2 (Ccr2). Instead, TLR9-driven inflammation induced a Ccr2-independent expansion of functionally enhanced extramedullary myeloid progenitors that correlated with the peripheral accumulation of monocytes in both wild-type and Ccr2−/− mice. Our data implicate inflammation-induced extramedullary monocytopoiesis as a peripheral source of newly produced TLR9 responsive monocytes capable of sustaining chronic TLR9 responses in vivo. These findings help to explain how chronic TLR-mediated inflammation may be perpetuated in autoimmune diseases and increase our understanding of how monocytes are produced and positioned during systemic inflammatory responses.

scholarly journals pMGF505-7R determines pathogenicity of African swine fever virus infection by inhibiting IL-1β and type I IFN production

2021 ◽  
Vol 17 (7) ◽  
pp. e1009733
Author(s):  
Jiangnan Li ◽  
Jie Song ◽  
Li Kang ◽  
Li Huang ◽  
Shijun Zhou ◽  
...  
Keyword(s):  
Immune Responses ◽  
Inflammatory Responses ◽  
African Swine Fever Virus ◽  
African Swine Fever ◽  
Innate Immune ◽  
Fever Virus ◽  
Type I ◽  
Type I Ifn ◽  
Innate Immune Responses

Inflammatory factors and type I interferons (IFNs) are key components of host antiviral innate immune responses, which can be released from the pathogen-infected macrophages. African swine fever virus (ASFV) has developed various strategies to evade host antiviral innate immune responses, including alteration of inflammatory responses and IFNs production. However, the molecular mechanism underlying inhibition of inflammatory responses and IFNs production by ASFV-encoded proteins has not been fully understood. Here we report that ASFV infection only induced low levels of IL-1β and type I IFNs in porcine alveolar macrophages (PAMs), even in the presence of strong inducers such as LPS and poly(dA:dT). Through further exploration, we found that several members of the multigene family 360 (MGF360) and MGF505 strongly inhibited IL-1β maturation and IFN-β promoter activation. Among them, pMGF505-7R had the strongest inhibitory effect. To verify the function of pMGF505-7R in vivo, a recombinant ASFV with deletion of the MGF505-7R gene (ASFV-Δ7R) was constructed and assessed. As we expected, ASFV-Δ7R infection induced higher levels of IL-1β and IFN-β compared with its parental ASFV HLJ/18 strain. ASFV infection-induced IL-1β production was then found to be dependent on TLRs/NF-κB signaling pathway and NLRP3 inflammasome. Furthermore, we demonstrated that pMGF505-7R interacted with IKKα in the IKK complex to inhibit NF-κB activation and bound to NLRP3 to inhibit inflammasome formation, leading to decreased IL-1β production. Moreover, we found that pMGF505-7R interacted with and inhibited the nuclear translocation of IRF3 to block type I IFN production. Importantly, the virulence of ASFV-Δ7R is reduced in piglets compared with its parental ASFV HLJ/18 strain, which may due to induction of higher IL-1β and type I IFN production in vivo. Our findings provide a new clue to understand the functions of ASFV-encoded pMGF505-7R and its role in viral infection-induced pathogenesis, which might help design antiviral agents or live attenuated vaccines to control ASF.

scholarly journals Obesity causes selective and long-lasting desensitization of AgRP neurons to dietary fat

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Lisa R Beutler ◽  
Timothy V Corpuz ◽  
Jamie S Ahn ◽  
Seher Kosar ◽  
Weimin Song ◽  
...  
Keyword(s):  
Weight Loss ◽  
Dietary Fat ◽  
High Fat Diet ◽  
Neural Circuits ◽  
Gastrointestinal Hormones ◽  
Food Cues ◽  
High Fat ◽  
Diet Induced Obesity ◽  
Obesity In Mice

Body weight is regulated by interoceptive neural circuits that track energy need, but how the activity of these circuits is altered in obesity remains poorly understood. Here we describe the in vivo dynamics of hunger-promoting AgRP neurons during the development of diet-induced obesity in mice. We show that high-fat diet attenuates the response of AgRP neurons to an array of nutritionally-relevant stimuli including food cues, intragastric nutrients, cholecystokinin and ghrelin. These alterations are specific to dietary fat but not carbohydrate or protein. Subsequent weight loss restores the responsiveness of AgRP neurons to exterosensory cues but fails to rescue their sensitivity to gastrointestinal hormones or nutrients. These findings reveal that obesity triggers broad dysregulation of hypothalamic hunger neurons that is incompletely reversed by weight loss and may contribute to the difficulty of maintaining a reduced weight.

scholarly journals CX3CL1 action on microglia protects from diet-induced obesity by restoring POMC neuronal excitability and melanocortin system activity impaired by high-fat diet feeding

2021 ◽  
Author(s):  
Jineta Banerjee ◽  
Mauricio D. Dorfman ◽  
Rachael Fasnacht ◽  
John D. Douglass ◽  
Alice C. Wyse-Jackson ◽  
...  
Keyword(s):  
High Fat Diet ◽  
Microglial Activation ◽  
Molecular Mechanisms ◽  
Melanocortin Receptor ◽  
High Fat ◽  
Diet Induced Obesity ◽  
Leptin Sensitivity ◽  
Neuron Excitability ◽  
Melanocortin Signaling

Objective: Diet-induced obesity (DIO) is associated with hypothalamic microglial activation and dysfunction of the melanocortin pathway, but the molecular mechanisms linking the two remain unclear. Previous studies have hypothesized that microglial inflammatory signaling is linked with impaired pro-opiomelanocortin (POMC) neuron function, but this mechanism has never been directly tested in vivo. We addressed this hypothesis using the specific microglial silencing molecule, CX3CL1 (fractalkine), to determine whether reducing hypothalamic microglial activation can restore POMC/melanocortin signaling in the brain to protect against DIO. Methods: We performed metabolic analyses in mice with targeted viral overexpression of CX3CL1 in the hypothalamus exposed to high fat diet (HFD). Electrophysiologic recording in hypothalamic slices from POMC-MAPT-GFP mice was used to determine the effects of HFD feeding and microglial silencing via minocycline or CX3CL1 on GFP-labeled POMC neurons. Finally, mice with hypothalamic overexpression of CX3CL1 received central treatment with the melanocortin receptor antagonist SHU-9119 to determine whether melanocortin signaling is required for the metabolic benefits of CX3CL1. Results: We found that targeted expression of both soluble and membrane-bound forms of CX3CL1 in the mediobasal hypothalamus potently reduced weight gain and increased leptin sensitivity in animals exposed to high fat diet. The protective effect of CX3CL1 rescued diet-induced changes in POMC neuron excitability and required intact melanocortin receptor signaling in vivo. Conclusion: Our results provide the first evidence that HFD-induced POMC neuron dysfunction involves microglial activation. Furthermore, our study suggests that the anti-obesity action of CX3CL1 is mediated through the restoration of POMC neuron excitability and melanocortin signaling.

A more pronounced effect of type III resistant starch vs. type II resistant starch on ameliorating hyperlipidemia in high fat diet-fed mice is associated with its supramolecular structural characteristics

2020 ◽  
Vol 11 (3) ◽  
pp. 1982-1995 ◽  
Author(s):  
Jiangbin Xu ◽  
Zhen Ma ◽  
Xiaoping Li ◽  
Liu Liu ◽  
Xinzhong Hu
Keyword(s):  
Resistant Starch ◽  
High Fat Diet ◽  
Supramolecular Structure ◽  
Structural Characteristics ◽  
Pronounced Effect ◽  
Type Ii ◽  
High Fat ◽  
Diet Induced Obesity ◽  
Relationship Of

The anti-obesity effects of two categories of lentil resistant starch (RS) including RS2 and RS3 on mice with high-fat diet-induced obesity and the supramolecular structure-in vivo physiological functionality relationship of RS were investigated.

Antagonism of peroxisome proliferator-activated receptor γ prevents high-fat diet-induced obesity in vivo

2006 ◽  
Vol 72 (1) ◽  
pp. 42-52 ◽  
Author(s):  
Ryosuke Nakano ◽  
Eiji Kurosaki ◽  
Shigeru Yoshida ◽  
Masanori Yokono ◽  
Akiyoshi Shimaya ◽  
...  
Keyword(s):  
High Fat Diet ◽  
Peroxisome Proliferator ◽  
High Fat ◽  
Peroxisome Proliferator Activated Receptor ◽  
Diet Induced Obesity
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