Adrenomedullin 2 Enhances Beiging in White Adipose Tissue Directly in an Adipocyte-autonomous Manner and Indirectly through Activation of M2 Macrophages.

Adrenomedullin 2 (ADM2) is an endogenous bioactive peptide belonging to the calcitonin gene-related peptide family. Our previous studies showed that overexpression of ADM2 in mice reduced obesity and insulin resistance by increasing thermogenesis in brown adipose tissue. However, the effects of ADM2 in another type of thermogenic adipocyte, beige adipocytes, remain to be understood. The plasma ADM2 levels were inversely correlated with obesity in humans, and adipo-ADM2-transgenic (tg) mice displayed resistance to high-fat diet-induced obesity with increased energy expenditure. Beiging of subcutaneous white adipose tissues (WAT) was more noticeably induced in high-fat diet-fed transgenic mice with adipocyte-ADM2 overexpression (adipo-ADM2-tg mice) than in WT animals. ADM2 treatment in primary rat subcutaneous adipocytes induced beiging with up-regulation of UCP1 and beiging-related marker genes and increased mitochondrial uncoupling respiration, which was mainly mediated by activation of the calcitonin receptor-like receptor (CRLR)·receptor activity-modifying protein 1 (RAMP1) complex and PKA and p38 MAPK signaling pathways. Importantly, this adipocyte-autonomous beiging effect by ADM2 was translatable to human primary adipocytes. In addition, M2 macrophage activation also contributed to the beiging effects of ADM2 through catecholamine secretion. Therefore, our study reveals that ADM2 enhances subcutaneous WAT beiging via a direct effect by activating the CRLR·RAMP1-cAMP/PKA and p38 MAPK pathways in white adipocytes and via an indirect effect by stimulating alternative M2 polarization in macrophages. Through both mechanisms, beiging of WAT by ADM2 results in increased energy expenditure and reduced obesity, suggesting ADM2 as a novel anti-obesity target.

Minimal-access video-assisted retroperitoneal and/or transperitoneal debridement (VARTD) in the management of infected walled-off pancreatic necrosis with deep extension: initial experience from a prospective single-arm study.

BACKGROUND: The currently preferred minimally invasive approaches have substantially improved outcomes of infected walled-off pancreatic necrosis (iWON). However, iWON with deep extension (iWONde) still poses a tricky challenge for sufficient necrosis evacuation by one stand-alone approach, often requiring repeated interventions. The aim of this study was to assess the effectiveness and safety of a minimal-access video-assisted retroperitoneal and/or transperitoneal debridement (hereafter called VARTD) in the management of iWONde. METHODS: Patients who had developed an iWONde were recruited to receive the VARTD in this prospective single-arm study. The primary efficacy endpoint was clinical improvement up to day 28 after the VARTD, defined as a ≥ 75% reduction in size of necrotic collection (in any axis) on CT and clinical resolution of sepsis or organ dysfunction. The primary safety endpoint was a composite of major complications or death during follow-up. Six-month postdischarge follow-up was available. RESULTS: Between July 18, 2018, and November 12, 2020, we screened 95 patients with necrotizing pancreatitis; of these, 21 iWONde patients (mean [SD] age, 42.9 [11.7] years; 10 [48%] women) were finally enrolled. The primary efficacy endpoint was achieved by most participants (14/21, 67%). No participants required repeated interventions. The primary safety endpoint occurred in six patients (29%). Except one in-hospital death attributable to repeated intra-abdominal hemorrhage, others were discharged without any major complication. CONCLUSIONS: The VARTD approach appears to have a reasonable efficacy with acceptable complication rates and thus might be an option for improving clinical management of iWONde. TRIAL REGISTRATION: This study is registered with Chinese Clinical Trial Registry (chictr.org.cn number, ChiCTR1800016950).

Intestinal hypoxia-inducible factor 2α regulates lactate levels to shape the gut microbiome and alter thermogenesis.

Accumulating evidence suggests that the gut microbiota regulates obesity through metabolite-host interactions. However, the mechanisms underlying such interactions have been unclear. Here, we found that intestinal hypoxia-inducible factor 2α (HIF-2α) positively regulates gut lactate by controlling the expression of intestinal Ldha. Intestine-specific HIF-2α ablation in mice resulted in lower lactate levels, and less Bacteroides vulgatus and greater Ruminococcus torques abundance, respectively. Together, these changes resulted in elevated taurine-conjugated cholic acid (TCA) and deoxycholic acid (DCA) levels and activation of the adipose G-protein-coupled bile acid receptor, GPBAR1 (TGR5). This activation upregulated expression of uncoupling protein (UCP) 1 and mitochondrial creatine kinase (CKMT) 2, resulting in elevation of white adipose tissue thermogenesis. Administration of TCA and DCA mirrored these phenotypes, and colonization with B. vulgatus and R. torques inhibited and induced thermogenesis, respectively. This work deepens our understanding of how host genes regulate the microbiome and provides novel strategies for alleviating obesity.

Suppressing the intestinal farnesoid X receptor/sphingomyelin phosphodiesterase 3 axis decreases atherosclerosis.

Intestinal farnesoid X receptor (FXR) signaling is involved in the development of obesity, fatty liver disease, and type 2 diabetes. However, the role of intestinal FXR in atherosclerosis and its potential as a target for clinical treatment have not been explored. The serum levels of fibroblast growth factor 19 (FGF19), which is encoded by an FXR target gene, were much higher in patients with hypercholesterolemia than in control subjects and were positively related to circulating ceramide levels, indicating a link between intestinal FXR, ceramide metabolism, and atherosclerosis. Among ApoE-/- mice fed a high-cholesterol diet (HCD), intestinal FXR deficiency (in FxrΔIE ApoE-/- mice) or direct FXR inhibition (via treatment with the FXR antagonist glycoursodeoxycholic acid [GUDCA]) decreased atherosclerosis and reduced the levels of circulating ceramides and cholesterol. Sphingomyelin phosphodiesterase 3 (SMPD3), which is involved in ceramide synthesis in the intestine, was identified as an FXR target gene. SMPD3 overexpression or C16:0 ceramide supplementation eliminated the improvements in atherosclerosis in FxrΔIE ApoE-/- mice. Administration of GUDCA or GW4869, an SMPD3 inhibitor, elicited therapeutic effects on established atherosclerosis in ApoE-/- mice by decreasing circulating ceramide levels. This study identified an intestinal FXR/SMPD3 axis that is a potential target for atherosclerosis therapy.

Gut microbiota-bile acid-interleukin-22 axis orchestrates polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) is characterized by androgen excess, ovulatory dysfunction and polycystic ovaries1, and is often accompanied by insulin resistance2. The mechanism of ovulatory dysfunction and insulin resistance in PCOS remains elusive, thus limiting the development of therapeutics. Improved metabolic health is associated with a relatively high microbiota gene content and increased microbial diversity3,4. This study aimed to investigate the impact of the gut microbiota and its metabolites on the regulation of PCOS-associated ovarian dysfunction and insulin resistance. Here, we report that Bacteroides vulgatus was markedly elevated in the gut microbiota of individuals with PCOS, accompanied by reduced glycodeoxycholic acid and tauroursodeoxycholic acid levels. Transplantation of fecal microbiota from women with PCOS or B. vulgatus-colonized recipient mice resulted in increased disruption of ovarian functions, insulin resistance, altered bile acid metabolism, reduced interleukin-22 secretion and infertility. Mechanistically, glycodeoxycholic acid induced intestinal group 3 innate lymphoid cell IL-22 secretion through GATA binding protein 3, and IL-22 in turn improved the PCOS phenotype. This finding is consistent with the reduced levels of IL-22 in individuals with PCOS. This study suggests that modifying the gut microbiota, altering bile acid metabolism and/or increasing IL-22 levels may be of value for the treatment of PCOS.

Publisher Correction: Gut microbiota-bile acid-interleukin-22 axis orchestrates polycystic ovary syndrome.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Activation of intestinal hypoxia-inducible factor 2α during obesity contributes to hepatic steatosis.

Nonalcoholic fatty liver disease is becoming the most common chronic liver disease in Western countries, and limited therapeutic options are available. Here we uncovered a role for intestinal hypoxia-inducible factor (HIF) in hepatic steatosis. Human-intestine biopsies from individuals with or without obesity revealed that intestinal HIF-2α signaling was positively correlated with body-mass index and hepatic toxicity. The causality of this correlation was verified in mice with an intestine-specific disruption of Hif2a, in which high-fat-diet-induced hepatic steatosis and obesity were substantially lower as compared to control mice. PT2385, a HIF-2α-specific inhibitor, had preventive and therapeutic effects on metabolic disorders that were dependent on intestine HIF-2α. Intestine HIF-2α inhibition markedly reduced intestine and serum ceramide levels. Mechanistically, intestine HIF-2α regulates ceramide metabolism mainly from the salvage pathway, by positively regulating the expression of Neu3, the gene encoding neuraminidase 3. These results suggest that intestinal HIF-2α could be a viable target for hepatic steatosis therapy.