Metabolic endotoxemia promotes adipose dysfunction and inflammation in human obesity

Impaired adipose tissue (AT) lipid handling and inflammation is associated with obesity-related metabolic diseases. Circulating lipopolysaccharides (LPSs) from gut microbiota (metabolic endotoxemia), proposed as a triggering factor for the low-grade inflammation in obesity, might also be responsible for AT dysfunction. Nevertheless, this hypothesis has not been explored in human obesity. To analyze the relationship between metabolic endotoxemia and AT markers for lipogenesis, lipid handling, and inflammation in human obesity, 33 patients with obesity scheduled for surgery were recruited and classified according to their LPS levels. Visceral and subcutaneous AT gene and protein expression were analyzed and adipocyte and AT in vitro assays performed. Subjects with obesity with a high degree of metabolic endotoxemia had lower expression of key genes for AT function and lipogenesis ( SREBP1, FABP4, FASN, and LEP) but higher expression of inflammatory genes in visceral and subcutaneous AT than subjects with low LPS levels. In vitro experiments corroborated that LPS are responsible for adipocyte and AT inflammation and downregulation of PPARG, SCD, FABP4, and LEP expression and LEP secretion. Thus, metabolic endotoxemia influences AT physiology in human obesity by decreasing the expression of factors involved in AT lipid handling and function as well as by increasing inflammation.

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Impact of Dietary Flavanols on Microbiota, Immunity and Inflammation in Metabolic Diseases

Nutrients ◽

10.3390/nu13030850 ◽

2021 ◽

Vol 13 (3) ◽

pp. 850

Author(s):

María Ángeles Martín ◽

Sonia Ramos

Keyword(s):

Immune System ◽

Fruits And Vegetables ◽

Metabolic Diseases ◽

Nuclear Factor Κb ◽

Low Grade ◽

Beneficial Effects ◽

Health And Disease ◽

Immunological Reactions ◽

And Function ◽

Positive Properties

Flavanols are natural occurring polyphenols abundant in fruits and vegetables to which have been attributed to beneficial effects on health, and also against metabolic diseases, such as diabetes, obesity and metabolic syndrome. These positive properties have been associated to the modulation of different molecular pathways, and importantly, to the regulation of immunological reactions (pro-inflammatory cytokines, chemokines, adhesion molecules, nuclear factor-κB [NF-κB], inducible enzymes), and the activity of cells of the immune system. In addition, flavanols can modulate the composition and function of gut microbiome in a prebiotic-like manner, resulting in the positive regulation of metabolic pathways and immune responses, and reduction of low-grade chronic inflammation. Moreover, the biotransformation of flavanols by gut bacteria increases their bioavailability generating a number of metabolites with potential to affect human metabolism, including during metabolic diseases. However, the exact mechanisms by which flavanols act on the microbiota and immune system to influence health and disease remain unclear, especially in humans where these connections have been scarcely explored. This review seeks to summarize recent advances on the complex interaction of flavanols with gut microbiota, immunity and inflammation focus on metabolic diseases.

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Histamine H2 receptor radioligands: triumphs and challenges

Future Medicinal Chemistry ◽

10.4155/fmc-2021-0058 ◽

2021 ◽

Author(s):

Steffen Pockes ◽

Katharina Tropmann

Keyword(s):

Receptor Expression ◽

In Vitro Assays ◽

Histamine H2 Receptor ◽

Drug Candidates ◽

Carbon 14 ◽

The Central Nervous System ◽

And Function ◽

Role And Function

Since the discovery of the histamine H2 receptor (H2R), radioligands were among the most powerful tools to investigate its role and function. Initially, radiolabeling was used to investigate human and rodent tissues regarding their receptor expression. Later, radioligands gained increasing significance as pharmacological tools in in vitro assays. Although tritium-labeling was mainly used for this purpose, labeling with carbon-14 is preferred for metabolic studies of drug candidates. After the more-or-less successful application of numerous labeled H2R antagonists, the recent development of the G protein-biased radioligand [3H]UR-KAT479 represents another step forward to elucidate the widely unknown role of the H2R in the central nervous system through future studies.

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Comparison of tyrosine kinase domain properties for the neurotrophin receptors TrkA and TrkB

Biochemical Journal ◽

10.1042/bcj20200695 ◽

2020 ◽

Vol 477 (20) ◽

pp. 4053-4070

Author(s):

Stephen C. Artim ◽

Anatoly Kiyatkin ◽

Mark A. Lemmon

Keyword(s):

Tyrosine Kinase ◽

Tyrosine Kinases ◽

Catalytic Efficiency ◽

Kinase Domain ◽

Tyrosine Kinase Domain ◽

Signaling Dynamics ◽

Cellular Context ◽

And Function ◽

High Degree

The tropomyosin-related kinase (Trk) family consists of three receptor tyrosine kinases (RTKs) called TrkA, TrkB, and TrkC. These RTKs are regulated by the neurotrophins, a class of secreted growth factors responsible for the development and function of neurons. The Trks share a high degree of homology and utilize overlapping signaling pathways, yet their signaling is associated with starkly different outcomes in certain cancers. For example, in neuroblastoma, TrkA expression and signaling correlates with a favorable prognosis, whereas TrkB is associated with poor prognoses. To begin to understand how activation of the different Trks can lead to such distinct cellular outcomes, we investigated differences in kinase activity and duration of autophosphorylation for the TrkA and TrkB tyrosine kinase domains (TKDs). We find that the TrkA TKD has a catalytic efficiency that is ∼2-fold higher than that of TrkB, and becomes autophosphorylated in vitro more rapidly than the TrkB TKD. Studies with mutated TKD variants suggest that a crystallographic dimer seen in many TrkA (but not TrkB) TKD crystal structures, which involves the kinase-insert domain, may contribute to this enhanced TrkA autophosphorylation. Consistent with previous studies showing that cellular context determines whether TrkB signaling is sustained (promoting differentiation) or transient (promoting proliferation), we also find that TrkB signaling can be made more transient in PC12 cells by suppressing levels of p75NTR. Our findings shed new light on potential differences between TrkA and TrkB signaling, and suggest that subtle differences in signaling dynamics can lead to substantial shifts in the cellular outcome.

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Tolerogenic Dendritic Cells Shape a Transmissible Gut Microbiota that Protects from Metabolic Diseases

10.2337/figshare.14687523 ◽

2021 ◽

Author(s):

Emelyne Lécuyer ◽

Tiphaine Le Roy ◽

Aurélie Gestin ◽

Amélie Lacombe ◽

Catherine Philippe ◽

...

Keyword(s):

Dendritic Cells ◽

Metabolic Diseases ◽

Intestinal Inflammation ◽

Intestinal Barrier ◽

Intestinal Barrier Function ◽

Low Grade ◽

Obesity And Diabetes ◽

Tolerogenic Dendritic Cells ◽

Tolerogenic Function ◽

And Function

Excess of chronic contact between microbial motifs and intestinal immune cells are known to trigger a low-grade inflammation involved in many pathologies such as obesity and diabetes. The important skewing of intestinal adaptive immunity in the context of diet-induced obesity (DIO) is well described but how dendritic cells (DCs) participate to these changes is still poorly documented. To address this question, transgenic mice with enhanced DCs lifespan and immunogenicity (DChBcl-2 mice) are challenged with a high-fat diet. Those mice display resistance to DIO and metabolic alterations. The DIO-resistant phenotype is associated with healthier parameters of intestinal barrier function and lower intestinal inflammation. DChBcl-2 DIO-resistant mice demonstrate a particular increase in tolerogenic DC numbers and function which is associated with strong intestinal IgA, Th17 and T regulatory immune responses. Microbiota composition and function analyses reveal that the DChBcl-2 mice microbiota is characterized by lower immunogenicity and an enhanced butyrate production. Cohousing experiments and fecal microbial transplantations are sufficient to transfer the DIO resistance status to WT mice demonstrating that maintenance of DCs tolerogenic ability sustains a microbiota able to drive DIO resistance. DCs tolerogenic function is revealed as a new potent target in metabolic disease management.

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Tolerogenic Dendritic Cells Shape a Transmissible Gut Microbiota that Protects from Metabolic Diseases

10.1101/2020.10.22.350033 ◽

2020 ◽

Author(s):

Emelyne Lécuyer ◽

Tiphaine Le Roy ◽

Aurélie Gestin ◽

Amélie Lacombe ◽

Catherine Philippe ◽

...

Keyword(s):

Dendritic Cells ◽

Metabolic Diseases ◽

Intestinal Inflammation ◽

Intestinal Barrier ◽

Intestinal Barrier Function ◽

Low Grade ◽

Obesity And Diabetes ◽

Tolerogenic Dendritic Cells ◽

Tolerogenic Function ◽

And Function

ABSTRACTExcess of chronic contact between microbial motifs and intestinal immune cells are known to trigger a low-grade inflammation involved in many pathologies such as obesity and diabetes.The important skewing of intestinal adaptive immunity in the context of diet-induced obesity (DIO) is well described but how dendritic cells (DCs) participate to these changes is still poorly documented. To address this question, transgenic mice with enhanced DCs lifespan and immunogenicity (DChBcl-2 mice), are challenged with a high fat diet.Those mice display resistance to DIO and metabolic alterations. The DIO resistant phenotype is associated with healthier parameters of intestinal barrier function and lower intestinal inflammation. DChBcl-2 DIO-resistant mice demonstrate a particular increase in tolerogenic DC numbers and function which is associated with strong intestinal IgA, Th17 and T regulatory immune responses.Microbiota composition and function analyses reveal that the DChBcl-2 mice microbiota is characterized by a lower immunogenicity and an enhanced butyrate production. Cohousing experiments and fecal microbial transplantations are sufficient to transfer the DIO resistance status to WT mice demonstrating that maintenance of DCs tolerogenic ability sustains a microbiota able to drive DIO resistance. DCs tolerogenic function is revealed as a new potent target in metabolic diseases management.

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FOXL2 is a Progesterone Target Gene in the Endometrium of Ruminants

International Journal of Molecular Sciences ◽

10.3390/ijms21041478 ◽

2020 ◽

Vol 21 (4) ◽

pp. 1478 ◽

Cited By ~ 1

Author(s):

Caroline Eozenou ◽

Audrey Lesage-Padilla ◽

Vincent Mauffré ◽

Gareth D. Healey ◽

Sylvaine Camous ◽

...

Keyword(s):

Oestrous Cycle ◽

In Vitro Assays ◽

Control Group ◽

Interferon Tau ◽

Forkhead Box ◽

Mrna And Protein Expression ◽

Exogenous Progesterone ◽

And Function ◽

Foxl2 Gene

Forkhead Box L2 (FOXL2) is a member of the FOXL class of transcription factors, which are essential for ovarian differentiation and function. In the endometrium, FOXL2 is also thought to be important in cattle; however, it is not clear how its expression is regulated. The maternal recognition of pregnancy signal in cattle, interferon-Tau, does not regulate FOXL2 expression. Therefore, in the present study, we examined whether the ovarian steroid hormones that orchestrate implantation regulate FOXL2 gene expression in ruminants. In sheep, we confirmed that FOXL2 mRNA and protein was expressed in the endometrium across the oestrous cycle (day 4 to day 15 post-oestrus). Similar to the bovine endometrium, ovine FOXL2 endometrial expression was low during the luteal phase of the oestrous cycle (4 to 12 days post-oestrus) and at implantation (15 days post-oestrus) while mRNA and protein expression significantly increased during the luteolytic phase (day 15 post-oestrus in cycle). In pregnant ewes, inhibition of progesterone production by trilostane during the day 5 to 16 period prevented the rise in progesterone concentrations and led to a significant increase of FOXL2 expression in caruncles compared with the control group (1.4-fold, p < 0.05). Ovariectomized ewes or cows that were supplemented with exogenous progesterone for 12 days or 6 days, respectively, had lower endometrial FOXL2 expression compared with control ovariectomized females (sheep, mRNA, 1.8-fold; protein, 2.4-fold; cattle; mRNA, 2.2-fold; p < 0.05). Exogenous oestradiol treatments for 12 days in sheep or 2 days in cattle did not affect FOXL2 endometrial expression compared with control ovariectomized females, except at the protein level in both endometrial areas in the sheep. Moreover, treating bovine endometrial explants with exogenous progesterone for 48h reduced FOXL2 expression. Using in vitro assays with COS7 cells we also demonstrated that progesterone regulates the FOXL2 promoter activity through the progesterone receptor. Collectively, our findings imply that endometrial FOXL2 is, as a direct target of progesterone, involved in early pregnancy and implantation.

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Interaction of Neuromelanin with Xenobiotics and Consequences for Neurodegeneration; Promising Experimental Models

Antioxidants ◽

10.3390/antiox10060824 ◽

2021 ◽

Vol 10 (6) ◽

pp. 824

Author(s):

Andrea Capucciati ◽

Fabio A. Zucca ◽

Enrico Monzani ◽

Luigi Zecca ◽

Luigi Casella ◽

...

Keyword(s):

Animal Models ◽

Neurodegenerative Diseases ◽

Brain Aging ◽

Experimental Models ◽

Test Tube ◽

Age Related ◽

And Function ◽

Endogenous Metabolites ◽

High Degree

Neuromelanin (NM) accumulates in catecholamine long-lived brain neurons that are lost in neurodegenerative diseases. NM is a complex substance made of melanic, peptide and lipid components. NM formation is a natural protective process since toxic endogenous metabolites are removed during its formation and as it binds excess metals and xenobiotics. However, disturbances of NM synthesis and function could be toxic. Here, we review recent knowledge on NM formation, toxic mechanisms involving NM, go over NM binding substances and suggest experimental models that can help identifying xenobiotic modulators of NM formation or function. Given the high likelihood of a central NM role in age-related human neurodegenerative diseases such as Parkinson’s and Alzheimer’s, resembling such diseases using animal models that do not form NM to a high degree, e.g., mice or rats, may not be optimal. Rather, use of animal models (i.e., sheep and goats) that better resemble human brain aging in terms of NM formation, as well as using human NM forming stem cellbased in vitro (e.g., mid-brain organoids) models can be more suitable. Toxicants could also be identified during chemical synthesis of NM in the test tube.

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Osteostat/Tumor Necrosis Factor Superfamily 18 Inhibits Osteoclastogenesis and Is Selectively Expressed by Vascular Endothelial Cells

Endocrinology ◽

10.1210/en.2005-0518 ◽

2006 ◽

Vol 147 (1) ◽

pp. 70-78 ◽

Cited By ~ 14

Author(s):

Bernardetta Nardelli ◽

Liubov Zaritskaya ◽

William McAuliffe ◽

Yansong Ni ◽

Clint Lincoln ◽

...

Keyword(s):

Endothelial Cells ◽

Vascular Endothelial Cells ◽

Early Stage ◽

Osteoclast Differentiation ◽

Precursor Cells ◽

In Vitro Assays ◽

Vascular Endothelial ◽

Tnf Superfamily ◽

And Function

Vascular endothelial cells (EC) participate in the process of bone formation through the production of factors regulating osteoclast differentiation and function. In this study, we report the selective expression in primary human microvascular EC of Osteostat/TNF superfamily 18, a ligand of the TNF superfamily. Osteostat protein is detectable in human microvascular EC and is highly up-regulated by IFN-α and IFN-β. Moreover, an anti-Osteostat antibody strongly binds to the vascular endothelium in human tissues, demonstrating that the protein is present in the EC layers surrounding blood vessels. Functional in vitro assays were used to define Osteostat involvement in osteoclastogenesis. Both recombinant and membrane-bound Osteostat inhibit differentiation of osteoclasts from monocytic precursor cells. Osteostat suppresses the early stage of osteoclastogenesis via inhibition of macrophage colony-stimulating factor-induced receptor activator of NF-κB (RANK) expression in the osteoclast precursor cells. This effect appears to be specific for the differentiation pathway of the osteoclast lineage, because Osteostat does not inhibit lipopolysaccharide-induced RANK expression in monocytes and dendritic cells, or activation-induced RANK expression in T cells. These findings demonstrate that Osteostat is a novel regulator of osteoclast generation and substantiate the major role played by the endothelium in bone physiology.

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LXRα Phosphorylation in Cardiometabolic Disease: Insight From Mouse Models

Endocrinology ◽

10.1210/endocr/bqaa089 ◽

2020 ◽

Vol 161 (7) ◽

Author(s):

Maud Voisin ◽

Matthew C Gage ◽

Natalia Becares ◽

Elina Shrestha ◽

Edward A Fisher ◽

...

Keyword(s):

Nuclear Receptors ◽

Posttranslational Modifications ◽

Physiological Response ◽

Metabolic Diseases ◽

Cardiometabolic Disease ◽

Nonalcoholic Fatty Liver ◽

Environmental Signals ◽

Powerful Means ◽

And Function

Abstract Posttranslational modifications, such as phosphorylation, are a powerful means by which the activity and function of nuclear receptors such as LXRα can be altered. However, despite the established importance of nuclear receptors in maintaining metabolic homeostasis, our understanding of how phosphorylation affects metabolic diseases is limited. The physiological consequences of LXRα phosphorylation have, until recently, been studied only in vitro or nonspecifically in animal models by pharmacologically or genetically altering the enzymes enhancing or inhibiting these modifications. Here we review recent reports on the physiological consequences of modifying LXRα phosphorylation at serine 196 (S196) in cardiometabolic disease, including nonalcoholic fatty liver disease, atherosclerosis, and obesity. A unifying theme from these studies is that LXRα S196 phosphorylation rewires the LXR-modulated transcriptome, which in turn alters physiological response to environmental signals, and that this is largely distinct from the LXR-ligand–dependent action.

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Gonadotrophin glycosylation and function

Journal of Endocrinology ◽

10.1677/joe.0.1250003 ◽

1990 ◽

Vol 125 (1) ◽

pp. 3-14 ◽

Cited By ~ 61

Author(s):

C. A. Wilson ◽

A. J. Leigh ◽

A. J. Chapman

Keyword(s):

Life Cycle ◽

Old Age ◽

Gonadal Steroids ◽

In Vitro Assays ◽

Heterogeneous Structure ◽

Gonadotrophin Releasing Hormone ◽

And Function ◽

Oligosaccharide Structures

ABSTRACT This review emphasizes the heterogeneous structure of the gonadotrophin hormones and the influence of different oligosaccharide structures on the bioactivity of these hormones. A summary has been made of the changes in biopotency of the gonadotrophins throughout the life-cycle of the human and in different endocrine states in the rat. In general it appears that the charge of the gonadotrophin conferred by the acid radicals attached to the terminal groups on the oligosaccharide structures strongly influences biopotency. Basic structures have a greater potency in in-vitro assays, but a short half-life in the circulation, while acidic isoforms are less potent, but have a longer circulatory time and are thus more active in in-vivo estimations. More basic forms are secreted over the adult reproductive years compared with the prepubertal period and old age. The glycosyl structure of the carbohydrate groups also alters in different endocrine states and is probably also important for the bioactivity and potency of the hormone. Gonadotrophin-releasing hormone (GnRH) and gonadal steroids can influence the type of isoform synthesized and released, and therefore affect the function of gonadotrophins. GnRH enhances glycosylation, sulphation and biopotency. Oestradiol potentiates the glycosylation induced by GnRH and reduces sialylation, while testosterone increases sialylation. Journal of Endocrinology (1990) 125, 3–14

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