Divergent responses to thermogenic stimuli in BAT and subcutaneous adipose tissue from interleukin 18 and interleukin 18 receptor 1-deficient mice

Brown and beige adipocytes recruitment in brown (BAT) or white adipose tissue, mainly in the inguinal fat pad (iWAT), meet the need for temperature adaptation in cold-exposure conditions and protect against obesity in face of hypercaloric diets. Using interleukin18 (Il18) and Il18 receptor 1- knockout (Il18r1-KO) mice, this study aimed to investigate the role of IL18 signaling in BAT and iWAT activation and thermogenesis under both stimuli. Il18-KO, extremely dietary obesity-prone as previously described, failed to develop diet-induced thermogenesis as assessed by BAT and iWAT Ucp1 mRNA levels. Overweight when fed standard chow but not HFD, HFD-fed Il18r1-KO mice exhibited increased iWAT Ucp1 gene expression. Energy expenditure was reduced in pre-obese Il18r1-KO mice and restored upon HFD-challenge. Cold exposure lead to similar results; Il18r1-KO mice were protected against acute body temperature drop, displaying a more brown-like structure, alternative macrophage activation and thermogenic gene expression in iWAT than WT controls. Opposite effects were observed in Il18-KO mice. Thus, Il18 and Il18r1 genetic ablation disparate effects on energy homeostasis are likely mediated by divergent BAT responses to thermogenic stimuli as well as iWAT browning. These results suggest that a more complex receptor-signaling system mediates the IL18 adipose-tissue specific effects in energy expenditure.This work has been supported by European Community (FP7/2007n° 245009: “NeuroFAST”), Ministerio de Economía y Competitividad (PP and MCGG: BFU2007–62683/BFI and PP, MCGG and CD: CIBERobn (CB06/03)) and Xunta de Galicia Grants (MCGG and LL: PGIDIT06PXIB208067PR and GPC2014/030). CIBER de Fisiopatología de la Obesidad y Nutrición is an initiative of ISCIIIS

Rational design of polyarginine nanocapsules intended to help peptides overcoming intestinal barriers

The aim of this work was to rationally design and characterize nanocapsules (NCs) composed of an oily core and a polyarginine (PARG) shell, intended for oral peptide delivery. The cationic polyaminoacid, PARG, and the oily core components were selected based on their penetration enhancing properties. Insulin was adopted as a model peptide to assess the performance of the NCs. After screening numerous formulation variables, including different oils and surfactants, we defined a composition consisting of oleic acid, sodium deoxycholate (SDC) and Span 80. This selected NCs composition, produced by the solvent displacement technique, exhibited the following key features: (i) an average size of 180 nm and a low polydispersity (0.1), (ii) a high insulin association efficacy (80–90% AE), (iii) a good colloidal stability upon incubation in simulated intestinal fluids (SIF, FaSSIF-V2, FeSSIF-V2), and (iv) the capacity to control the release of the associated insulin for > 4 h. Furthermore, using the Caco-2 model cell line, PARG nanocapsules were able to interact with the enterocytes, and reversibly modify the TEER of the monolayer. Both cell adhesion and membrane permeabilization could account for the pronounced transport of the NCs-associated insulin (3.54%). This improved interaction was also visualized by confocal fluorescent microscopy following oral administration of PARG nanocapsulesto mice. Finally, in vivo efficacy studies performed in normoglycemic rats showed a significant decrease in their plasma glucose levels after treatment. In conclusion, here we disclose key formulation elements for making possible the oral administration of peptidesThis work was supported by the European TRANS-INT Consortium, which received funding from the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement No. 281035. Z. Niu also would like to thank the Chinese Scholarship Council for his scholarshipS

Melanin-Concentrating Hormone acts through hypothalamic kappa opioid system and p70S6K to stimulate acute food intake.

Melanin-Concentrating Hormone (MCH) is one of the most relevant orexigenic factors specifically located in the lateral hypothalamic area (LHA), with its physiological relevance demonstrated in studies using several genetically manipulated mice models. However, the central mechanisms controlling MCH-induced hyperphagia remain largely uncharacterized. Here, we show that central injection of MCH in mice deficient for kappa opoid receptor (k-OR) failed to stimulate feeding. To determine the hypothalamic area responsible for this MCH/k-OR interaction, we performed virogenetic studies and found that downregulation of k-OR by adeno-associated viruses (shOprk1-AAV) in LHA, but not in other hypothalamic nuclei, was sufficient to block MCH-induced food intake. Next, we sought to investigate the molecular signaling pathway within the LHA that mediates acute central MCH stimulation of food intake. We found that MCH activates k-OR and that increased levels of phosphorylated extracellular signal regulated kinase (ERK) are associated with downregulation of phospho-S6 Ribosomal Protein. This effect was prevented when a pharmacological inhibitor of k-OR was co-administered with MCH. Finally, the specific activation of the direct upstream regulator of S6 (p70S6K) in the LHA attenuated MCH-stimulated food consumption. Our results reveal that lateral hypothalamic k-OR system modulates the orexigenic action of MCH via the p70S6K/S6 pathway

The interaction of protamine nanocapsules with the intestinal epithelium: A mechanistic approach.

Single-layer protamine and double layer polysialic acid (PSA)/protamine nanocapsules (NCs) were designed in order to be used as carriers to facilitate the transport of macromolecules across the intestinal epithelium. The rational for the design of these NCs was based on that protamine is a non-toxic yet potent cell-penetrating peptide, capable of translocating protein cargos through cell membranes, while PSA is a low molecular weight polysaccharide used to enhance the stability of macromolecules and nanocarriers. The aim of this work was to study in vitro the mechanism of interaction of these NCs with different intestinal cell models (Caco-2, Caco-2/Raji mimicking follicle associated epithelium and Caco-2/HT29-MTX to study the effect of mucus). For this, a fluorescent marker, TAMRA was covalently linked to protamine. The interaction and transport of the NCs with the Caco-2 cells was found to be concentration, temperature and size dependent. In all cases, the double layer PSA-protamine NCs exhibited a significantly higher transport compared to protamine NCs. On the other hand, the transport of the NCs was significantly higher in the co-culture (Caco-2/Raji monolayer) compared to the monoculture model (Caco-2 monolayer), implying that M cells are involved in the transport of these nanosystems. The formulations, administered intra-jejunally to healthy rats (4h fasting) resulted in a moderate reduction of the glucose levels (20% reduction), which lasted for up to 4h. This work raises prospects that protamine-based nanocapsules may have the potential as oral peptide delivery nanocarriers

Hypothalamic κ-opioid receptor modulates the orexigenic effect of ghrelin

The opioid system is well recognized as an important regulator of appetite and energy balance. We now hypothesized that the hypothalamic opioid system might modulate the orexigenic effect of ghrelin. Using pharmacological and gene silencing approaches, we demonstrate that ghrelin utilizes a hypothalamic ?-opioid receptor (KOR) pathway to increase food intake in rats. Pharmacological blockade of KOR decreases the acute orexigenic effect of ghrelin. Inhibition of KOR expression in the hypothalamic arcuate nucleus is sufficient to blunt ghrelin-induced food intake. By contrast, the specific inhibition of KOR expression in the ventral tegmental area does not affect central ghrelin-induced feeding. This new pathway is independent of ghrelin-induced AMP-activated protein kinase activation, but modulates the levels of the transcription factors and orexigenic neuropeptides triggered by ghrelin to finally stimulate feeding. Our novel data implicate hypothalamic KOR signaling in the orexigenic action of ghrelin

Absence of Intracellular Ion Channels TPC1 and TPC2 Leads to Mature-Onset Obesity in Male Mice, Due to Impaired Lipid Availability for Thermogenesis in Brown Adipose Tissue

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Hypothalamic κ-Opioid Receptor Modulates the Orexigenic Effect of Ghrelin

The opioid system is well recognized as an important regulator of appetite and energy balance. We now hypothesized that the hypothalamic opioid system might modulate the orexigenic effect of ghrelin. Using pharmacological and gene silencing approaches, we demonstrate that ghrelin utilizes a hypothalamic κ-opioid receptor (KOR) pathway to increase food intake in rats. Pharmacological blockade of KOR decreases the acute orexigenic effect of ghrelin. Inhibition of KOR expression in the hypothalamic arcuate nucleus is sufficient to blunt ghrelin-induced food intake. By contrast, the specific inhibition of KOR expression in the ventral tegmental area does not affect central ghrelin-induced feeding. This new pathway is independent of ghrelin-induced AMP-activated protein kinase activation, but modulates the levels of the transcription factors and orexigenic neuropeptides triggered by ghrelin to finally stimulate feeding. Our novel data implicate hypothalamic KOR signaling in the orexigenic action of ghrelin