Adiponectin regulates expression of hepatic genes critical for glucose and lipid metabolism

New Insights in the Diagnostic Potential of Sex Hormone-Binding Globulin (SHBG)-Clinical Approach

SHBG is a glycoprotein that not only controls serum sex hormone levels but is also strongly correlated with metabolic syndrome, cardiovascular risk, thyroid function, gynecological conditions, and even the process of carcinogenesis. Synthesis of SHBG is controlled by many factors related to obesity, lipogenesis, inflammatory status, and genetic predisposition. By influencing the bioavailability of sex hormones, SHBG regulates their effects not only on the reproductive system, but also cardiomyocytes, vascular epithelium, and more. In this review, we aim to gather and summarize current knowledge on the physiology of SHBG and its association with cardiovascular disease, metabolic syndrome, DM 2, thyroid function, PCOS, hypogonadism, infertility, and its correlations with oral contraception. What is more, genetic alterations are mentioned to highlight SHBG as a potential new diagnostic marker. Furthermore, we assess the clinical usefulness of this parameter in the diagnosis and treatment of patients suffering from the above-specified conditions.

Adiponectin receptor agonist AdipoRon regulates glucose and lipid metabolism via PPARγ signaling pathway in hepatocytes of large yellow croaker (Larimichthys crocea)

Activation of adiponectin receptors (AdipoRs) has been shown to regulate glucose and lipid metabolism in mammalian hepatocytes. However, much less is known for their roles in fish. The current study demonstrated that AdipoRon, a small-molecule activator of AdipoRs, modulated glucose and lipid metabolism in large yellow croaker. In hepatocytes of large yellow croaker, AdipoRon upregulated the mRNA expression of adipors and appl1, while increasing phosphorylation levels of AMPK and AKT. These changes indicate the activation of AdipoR-mediated signaling. Furthermore, AdipoRon promoted glucose uptake, increased intracellular glucose content, as well as upregulated genes involved in glycogen synthesis and glycolysis whereas downregulated gluconeogenesis-related genes. On the other hand, AdipoRon facilitated free fatty acid (FFA) absorption by increasing the expression of fatty acid transport genes (fat/cd36, fatp1, and fabp11). It also enhanced triglyceride (TG) synthesis, evidenced by increased triglyceride levels and upregulation of dgat2 and PPARγ, which is consistent with the effect of adiponectin (APN) in large yellow croaker. Additional evidence suggested that inhibition of PPARγ with GW9662 reduced the effects of AdipoRon on glucose uptake and lipid metabolism, indicating that PPARγ is a key mediator in these metabolic regulations. Overall, AdipoRon was found to modulate multiple metabolic processes in hepatocytes of large yellow croaker via PPARγ signaling pathway, and these findings suggested that AdipoRon might contribute to beneficial effects on metabolic homeostasis in teleosts.

Curcumin mitigates obesity-driven dysbiosis and liver steatosis while promoting browning and thermogenesis in white adipose tissue of high-fat diet-fed mice

Curcumin, recognized for its antioxidant and anti-inflammatory properties, is a promising dietary supplement for liver protection. However, its role in preventing obesity-induced hepatic steatosis is not fully understood. This study aims to show that curcumin mitigates hepatic steatosis and promotes browning and thermogenesis in white adipose tissue (WAT) under obesity. Male C57BL/6 mice were assigned to four groups: standard diet (STD), STD supplemented with 100 mg/kg curcumin, high-fat diet (HFD), or HFD supplemented with 100 mg/kg curcumin, administered for 4 weeks. Compared to STD mice, HFD-fed mice exhibited significantly greater body weight, epididymal fat mass, liver weight, postprandial blood glucose (PBG), insulin, and plasma/hepatic alanine aminotransferase (ALT) and triglyceride (TG) levels, alongside an inflammatory response and macrophage infiltration. Additionally, HFD-fed mice showed reduced adiponectin, adiponectin receptor-1, and PI3K/AKT phosphorylation in liver tissue. Except for liver weight, these effects were reversed in curcumin-treated HFD mice. Curcumin inhibited adipocyte hypertrophy and elevated the expression of PGC-1α, PPARγ, and UCP-1 proteins, as well as Zic1, Prdm16, Tnfrsf9, and Tmem26 genes in epididymal fat pads (EFPs). It also significantly altered gut microbiota composition, reducing pro-inflammatory bacteria such as Helicobacter, Oscillospira, Parabacteroides, and Alistipes, thereby alleviating intestinal dysbiosis and improving obesity-related metabolic parameters. In conclusion, curcumin's protective effects against hepatic steatosis and adiposity in HFD-fed mice stem from its ability to upregulate adiponectin, enhance insulin signaling, promote WAT browning, increase thermogenesis, and modulate intestinal dysbiosis.

Adiponectin signaling regulates urinary bladder function by blunting smooth muscle purinergic contractility

Lower urinary tract symptoms (LUTS) affect approximately 50% of the population over 40 years of age and are strongly associated with obesity and metabolic syndrome. Adipose tissue plays a key role in obesity/metabolic syndrome by releasing adipokines that regulate systemic energy/lipid metabolism, insulin resistance, and inflammation. Adiponectin (ADPN), the most abundant adipokine, modulates energy/metabolism homeostasis through its insulin-sensitizing and antiinflammatory effects. Human plasma ADPN levels are inversely associated with obesity and diabetes. To the best of our knowledge, the role of adipokines such as ADPN in the LUTS associated with obesity/metabolic syndrome remains unknown. We have tested such a possible role in a global ADPN-knockout (Adpn-/-) mouse model. Adpn-/- mice exhibited increased voiding frequency, small voids, and reduced bladder smooth muscle (BSM) contractility, with absence of purinergic contraction. Molecular examination indicated significantly altered metabolic and purinergic pathways. The ADPN receptor agonist AdipoRon was found to abolish acute BSM contraction. Intriguingly, both AMPK activators and inhibitors also abolished BSM purinergic contraction. These data indicate the important contribution of what we believe is a novel ADPN signaling pathway to the regulation of BSM contractility. Dysregulation of this ADPN signaling pathway might be an important mechanism leading to LUTS associated with obesity/metabolic syndrome.

Adiponectin Signaling Regulates Urinary Bladder Function by Blunting Smooth Muscle Purinergic Contractility

Lower urinary tract symptoms (LUTS) affect ∼ 50% of the population aged >40 years and are strongly associated with obesity and metabolic syndrome. Adipose tissue plays a key role in obesity/metabolic syndrome by releasing adipokines that regulate systemic energy/lipid metabolism, insulin resistance, and inflammation. Adiponectin (ADPN), the most abundant adipokine, modulates energy/metabolism homeostasis through its insulin-sensitizing and anti-inflammatory effects. Human plasma ADPN levels are inversely associated with obesity and diabetes. The role of adipokines such as ADPN in the LUTS associated with obesity/metabolic syndrome remains unknown. We have tested such a possible role in a global ADPN knockout mouse model ( Adpn -/- ). Adpn -/- mice exhibited increased voiding frequency, small voids, and reduced bladder smooth muscle (BSM) contractility with absence of purinergic contraction. Molecular examination indicated significantly altered metabolic and purinergic pathways. The ADPN receptor agonist AdipoRon was found to abolish acute BSM contraction. Intriguingly, both AMPK activators and inhibitors also abolished BSM purinergic contraction. These data indicate the important contribution of a novel ADPN signaling pathway to the regulation of BSM contractility. Dysregulation of this ADPN signaling pathway might be an important mechanism leading to LUTS associated with obesity/metabolic syndrome.

ARTICLE HIGHLIGHTS

Lower urinary tract symptom (LUTS) is strongly associated with obesity and metabolic syndrome, however, the underlying molecular mechanisms are missing. Dysregulation of adipokine signaling could be the link for this association.Whether adiponectin, the most abundant adipokine, plays a role in regulating bladder function and dysfunction.Mice null for adiponectin exhibited increased voiding frequency, small voids, and reduced bladder smooth muscle contractility, with corresponding metabolic and purinergic pathway changes.Dysregulation of adiponectin signaling might be an important mechanism leading to LUTS associated with obesity/metabolic syndrome.

Overview of a novel osmotin abolishes abnormal metabolic-associated adiponectin mechanism in Alzheimer's disease: Peripheral and CNS insights

Alzheimer's disease (AD) is a degenerative brain disease that affects millions of people worldwide. It is caused by abnormalities in cholinergic neurons, oxidative stress, and inflammatory cascades. The illness is accompanied by personality changes, memory issues, and dementia. Metabolic signaling pathways help with fundamental processes like DNA replication and RNA transcription. Being adaptable is essential for both surviving and treating illness. The body's metabolic signaling depends on adipokines, including adiponectin (APN) and other adipokines secreted by adipose tissues. Energy homeostasis is balanced by adipokines, and nutrients. Overconsumption of nutrients messes with irregular signaling of adipokines, such as APN in both peripheral and brain which leads to neurodegeneration, such as AD. Despite the failure of traditional treatments like memantine and cholinesterase inhibitors, natural plant bioactive substances like Osmotin (OSM) have been given a focus as potential therapeutics due to their antioxidant properties, better blood brain barrier (BBB) permeability, excellent cell viability, and especially nanoparticle approaches. The review highlights the published preclinical literature regarding the role of OSM in AD pathology while there is a need for more research to investigate the hidden therapeutic potential of OSM which may open a new gateway and further strengthen its healing role in the pathogenesis of neurodegeneration, especially AD.

EGCG alleviates heat-stress-induced fat deposition by targeting HSP70 through activation of AMPK-SIRT1-PGC-1α in porcine subcutaneous preadipocytes

Obesity has emerged as a prominent global health concern, with heat stress posing a significant challenge to both human health and animal well-being. Despite a growing interest in environmental determinants of obesity, very few studies have examined the associations between heat stress-related environmental factors and adiposity. Consequently, there exists a clear need to understand the molecular mechanisms underlying the obesogenic effects of heat stress and to formulate preventive strategies. This study focused on culturing porcine subcutaneous preadipocytes at 41.5 ℃ to induce heat stress, revealing that this stressor triggered apoptosis and fat deposition. Analysis demonstrated an upregulation in the expression of HSP70, BAX, adipogenesis-related genes (PPARγ, AP2, CEBPα and FAS), the p-AMPK/AMPK ratio and SIRT1, PGC-1α in the heat stress group compared to the control group (P < 0.05). Conversely, the expression of lipid lysis-related genes (ATGL, HSL and LPL) and Bcl-2 decreased in the heat stress group compared to the control group (P < 0.05). Furthermore, subsequent activator and/or inhibitor experiments validated that heat stress modulated HSP70 and AMPK signalling pathways to enhance lipogenesis and inhibit lipolysis in porcine subcutaneous preadipocytes. Importantly, this study reveals, for the first time, that EGCG mitigates heat-stress-induced fat deposition by targeting HSP70 through the activation of AMPK-SIRT1-PGC-1α in porcine subcutaneous preadipocytes. These findings elucidate the molecular mechanisms contributing to heat stress-induced obesity and provide a foundation for the potential clinical utilisation of EGCG as a preventive measure against both heat stress and obesity.

The adiponectin-derived peptide ALY688 protects against the development of metabolic dysfunction-associated steatohepatitis

Metabolic dysfunction-associated steatohepatitis (MASH) is the severe form of non-alcoholic fatty liver disease which has a high potential to progress to cirrhosis and hepatocellular carcinoma, yet adequate effective therapies are lacking. Hypoadiponectinemia is causally involved in the pathogenesis of MASH. This study investigated the pharmacological effects of adiponectin replacement therapy with the adiponectin-derived peptide ALY688 (ALY688-SR) in a mouse model of MASH. Human induced pluripotent stem (iPS) cell-derived hepatocytes were used to test cytotoxicity and signaling of unmodified ALY688 in vitro. High-fat diet with low methionine and no added choline (CDAHF) was used to induce MASH and test the effects of ALY688-SR in vivo. Histological MASH activity score (NAS) and fibrosis score were determined to assess the effect of ALY688-SR. Transcriptional characterization of mice through RNA sequencing was performed to indicate potential molecular mechanisms involved. In cultured hepatocytes, ALY688 efficiently induced adiponectin-like signaling, including the AMP-activated protein kinase and p38 mitogen-activated protein kinase pathways, and did not elicit cytotoxicity. Administration of ALY688-SR in mice did not influence body weight but significantly ameliorated CDAHF-induced hepatic steatosis, inflammation, and fibrosis, therefore effectively preventing the development and progression of MASH. Mechanistically, ALY688-SR treatment markedly induced hepatic expression of genes involved in fatty acid oxidation, whereas it significantly suppressed the expression of pro-inflammatory and pro-fibrotic genes as demonstrated by transcriptomic analysis. ALY688-SR may represent an effective approach in MASH treatment. Its mode of action involves inhibition of hepatic steatosis, inflammation, and fibrosis, possibly via canonical adiponectin-mediated signaling.

Metformin Inefficiency to Lower Lipids in Vitamin B12 Deficient HepG2 Cells Is Alleviated via Adiponectin-AMPK Axis

Background: Prolonged metformin treatment decreases vitamin B12 (B12) levels, whereas low B12 is associated with dyslipidaemia. Some studies have reported that metformin has no effect on intrahepatic triglyceride (TG) levels. Although AMP-activated protein kinase (AMPK) activation via adiponectin lowers hepatic TG content, its role in B12 deficiency and metformin has not been explored. We investigated whether low B12 impairs the beneficial effect of metformin on hepatic lipid metabolism via the AMPK-adiponectin axis. Methods: HepG2 was cultured using custom-made B12-deficient Eagle's Minimal Essential Medium (EMEM) in different B12-medium concentrations, followed by a 24-h metformin/adiponectin treatment. Gene and protein expressions and total intracellular TG were measured, and radiochemical analysis of TG synthesis and seahorse mitochondria stress assay were undertaken. Results: With low B12, total intracellular TG and synthesized radiolabelled TG were increased. Regulators of lipogenesis, cholesterol and genes regulating fatty acids (FAs; TG; and cholesterol biosynthesis were increased. FA oxidation (FAO) and mitochondrial function were decreased, with decreased pAMPKα and pACC levels. Following metformin treatment in hepatocytes with low B12, the gene and protein expression of the above targets were not alleviated. However, in the presence of adiponectin, intrahepatic lipid levels with low B12 decreased via upregulated pAMPKα and pACC levels. Again, combined adiponectin and metformin treatment ameliorated the low B12 effect and resulted in increased pAMPKα and pACC, with a subsequent reduction in lipogenesis, increased FAO and mitochondrion function. Conclusions: Adiponectin co-administration with metformin induced a higher intrahepatic lipid-lowering effect. Overall, we emphasize the potential therapeutic implications for hepatic AMPK activation via adiponectin for a clinical condition associated with B12 deficiency and metformin treatment.

Effects of In Utero PFOS Exposure on Epigenetics and Metabolism in Mouse Fetal Livers

Prenatal exposure to perfluorooctanesulfonate (PFOS) increases fetus' metabolic risk; however, the investigation of the underlying mechanism is limited. In this study, pregnant mice in the gestational days (GD, 4.5-17.5) were exposed to PFOS (0.3 and 3 μg/g of body weight). At GD 17.5, PFOS perturbed maternal lipid metabolism and upregulated metabolism-regulating hepatokines (Angptl4, Angptl8, and Selenop). Mass-spectrometry imaging and whole-genome bisulfite sequencing revealed, respectively, selective PFOS localization and deregulation of gene methylation in fetal livers, involved in inflammation, glucose, and fatty acid metabolism. PCR and Western blot analysis of lipid-laden fetal livers showed activation of AMPK signaling, accompanied by significant increases in the expression of glucose transporters (Glut2/4), hexose-phosphate sensors (Retsat and ChREBP), and the key glycolytic enzyme, pyruvate kinase (Pk) for glucose catabolism. Additionally, PFOS modulated the expression levels of PPARα and PPARγ downstream target genes, which simultaneously stimulated fatty acid oxidation (Cyp4a14, Acot, and Acox) and lipogenesis (Srebp1c, Acaca, and Fasn). Using human normal hepatocyte (MIHA) cells, the underlying mechanism of PFOS-elicited nuclear translocation of ChREBP, associated with a fatty acid synthesizing pathway, was revealed. Our finding implies that in utero PFOS exposure altered the epigenetic landscape associated with dysregulation of fetal liver metabolism, predisposing postnatal susceptibility to metabolic challenges.

Targeted Activation of HNF4α by AMPK Inhibits Apoptosis and Ameliorates Neurological Injury Caused by Cardiac Arrest in Rats

Previous studies have shown that AMPK plays an important role in cerebral ischemia-reperfusion injury by participating in apoptosis, but the exact mechanism and target of action remains unclear. This study aimed to investigate the protective mechanism of AMPK activation on brain injury secondary to cardiac arrest. HE, Nills and TUNEL assays were used to evaluate neuronal damage and apoptosis. The relationships between AMPK, HNF4α and apoptotic genes were verified by ChIP-seq, dual-luciferase and WB assays. The results showed that AMPK improved the 7-day memory function of rats, and reduced neuronal cell injury and apoptosis in the hippocampal CA1 region after ROSC, while the use of HNF4α inhibitor weakened the protective effect of AMPK. Further research found that AMPK positively regulated the expression of HNF4α, and AMPK could promote the expression of Bcl-2 and inhibit the expression of Bax and Cleaved-Caspase 3. In vitro experiments showed that AMPK ameliorated neuronal injury by inhibiting apoptosis through the activation of HNF4α. Combined with ChIP-seq, JASPAR analysis and Dual-luciferase assay, the binding site of HNF4α to the upstream promoter of Bcl-2 was found. Taken together, AMPK attenuates brain injury after CA by activating HNF4α to target Bcl-2 to inhibit apoptosis.

Downregulation of PMP22 ameliorates myelin defects in iPSC-derived human organoid cultures of CMT1A

Charcot-Marie-Tooth disease is the most common inherited disorder of the PNS. CMT1A accounts for 40-50% of all cases and is caused by a duplication of the PMP22 gene on chromosome 17, leading to dysmyelination in the PNS. Patient-derived models to study such myelination defects are lacking as the in vitro generation of human myelinating Schwann cells has proved to be particularly challenging. Here, we present an induced pluripotent stem cell-derived organoid culture, containing various cell types of the PNS, including myelinating human Schwann cells, which mimics the human PNS. Single-cell analysis confirmed the PNS-like cellular composition and provides insight into the developmental trajectory. We used this organoid model to study disease signatures of CMT1A, revealing early ultrastructural myelin alterations, including increased myelin periodic line distance and hypermyelination of small axons. Furthermore, we observed the presence of onion-bulb-like formations in a later developmental stage. These hallmarks were not present in the CMT1A-corrected isogenic line or in a CMT2A iPSC line, supporting the notion that these alterations are specific to CMT1A. Downregulation of PMP22 expression using short-hairpin RNAs or a combinatorial drug consisting of baclofen, naltrexone hydrochloride and D-sorbitol was able to ameliorate the myelin defects in CMT1A-organoids. In summary, this self-organizing organoid model can capture biologically meaningful features of the disease and capture the physiological complexity, forms an excellent model for studying demyelinating diseases and supports the therapeutic approach of reducing PMP22 expression.

Growth hormone treatment does not augment the anti-diabetic effects of liraglutide in UCD-T2DM rats

INTRODUCTION

The incretin hormone glucagon-like peptide-1 (GLP-1) slows gastric emptying, increases satiety and enhances insulin secretion. GLP-1 receptor agonists, such as liraglutide, are used therapeutically in humans to improve glycaemic control and delay the onset of type 2 diabetes mellitus (T2DM). In UCD-T2DM rats, a model of polygenic obesity and insulin resistance, we have previously reported that daily liraglutide administration delayed diabetes onset by >4 months. Growth hormone (GH) may exert anti-diabetic effects, including increasing β-cell mass and insulin secretion, while disrupting GH signalling in mice reduces both the size and number of pancreatic islets. We therefore hypothesized that GH supplementation would augment liraglutide's anti-diabetic effects.

METHODS

Male UCD-T2DM rats were treated daily with GH (0.3 mg/kg) and/or liraglutide (0.2 mg/kg) from 2 months of age. Control (vehicle) and food-restricted (with food intake matched to liraglutide-treated rats) groups were also studied. The effects of treatment on diabetes onset and weight gain were assessed, as well as measures of glucose tolerance, lipids and islet morphology.

RESULTS

Liraglutide treatment significantly reduced food intake and body weight and improved glucose tolerance and insulin sensitivity, relative to controls. After 4.5 months, none of the liraglutide-treated rats had developed T2DM (overall p = .019). Liraglutide-treated rats also displayed lower fasting triglyceride (TG) concentrations and lower hepatic TG content, compared to control rats. Islet morphology was improved in liraglutide-treated rats, with significantly increased pancreatic insulin content (p < .05 vs. controls). Although GH treatment tended to increase body weight (and gastrocnemius muscle weight), there were no obvious effects on diabetes onset or other diabetes-related outcomes.

CONCLUSION

GH supplementation did not augment the anti-diabetic effects of liraglutide.

Congenital adiponectin deficiency mitigates high-fat-diet-induced obesity in gonadally intact male and female, but not in ovariectomized mice

Epidemiological literature indicates that women are less susceptible to type II diabetes (T2D) than males. The general consensus is that estrogen is protective, whereas its deficiency in post-menopause is associated with adiposity and impaired insulin sensitivity. However, epidemiological data suggests that males are more prone to developing T2D, and at a lower BMI, compared to females during post-menopausal years; suggesting that another factor, other than estrogen, protects females. We proposed to determine if adiponectin (APN) serves as this protective factor. An initial experiment was performed in which gonadally intact male and female mice were fed either a purified low-fat diet (LFD) or high-fat diet (HFD) (40% kcals from fat) for 16 weeks. An additional group of HFD ovariectomy (OVX) mice were included to assess estrogen deficiency’s impact on obesity. Body composition, adipose tissue inflammation, ectopic lipid accumulation as well as glucose metabolism and insulin resistance were assessed. In corroboration with previous data, estrogen deficiency (OVX) exacerbated HFD-induced obesity in female mice. However, despite a higher body fat percentage and a similar degree of hepatic and skeletal muscle lipid accumulation, female OVX HFD-fed mice exhibited enhanced insulin sensitivity relative to HFD-fed males. Therefore, a subsequent HFD experiment was performed utilizing male and female (both gonadally intact and OVX) APN deficient mice (APN^−/−) and wildtype littermates to determine if APN is the factor which protects OVX females from the similar degree of metabolic dysfunction as males in the setting of obesity. Indirect calorimetry was used to determine observed phenotype differences. APN deficiency limited adiposity and mitigated HFD-induced insulin resistance and adipose tissue inflammation in gonadally intact male and female, but not in OVX mice. Using indirect calorimetry, we uncovered that slight, but non-statistically significant differences in food intake and energy expenditure leading to a net difference in energy balance likely explain the reduced body weight exhibited by male APN-deficient mice. In conclusion, congenital APN deficiency is protective against obesity development in gonadally intact mice, however, in the setting of estrogen deficiency (OVX) this is not true. These findings suggest that gonadal status dictates the protective effects of congenital APN deficiency in the setting of HFD-induced obesity.

In Vitro Hepatoprotective and Human Gut Microbiota Modulation of Polysaccharide-Peptides in Pleurotus citrinopileatus

Pleurotus citrinopileatus, a golden oyster mushroom, is popular in Asia and has pharmacological functions. However, the effects of polysaccharide-peptides extracted from Pleurotus citrinopileatus and underlying mechanism on digestive systme have not yet been clarified. Here, we determined the composition of two polysaccharide-peptides (PSI and PSII) from P. citrinopileatus and investigated the protective effects of on hepatoprotective and gut microbiota. The results showed that PSI and PSII were made up of similar monosaccharide moieties, except for the varying ratios. Furthermore, PSI and PSII showed that they have the hepatoprotective effects and significantly increased the viabilities and cellular total superoxide dismutase activities increased significantly in HepG2 cells. Intracellular triglyceride content and extracellular alanine aminotransferase and aspartate transaminase contents markedly decreased following treatment with 40 and 50 μg/mL PSI and PSII, respectively. Moreover, PSI and PSII activated the adiponectin pathway and reduced lipid accumulation in liver cells. PSI and PSII elevated short-chain fatty acid concentrations, especially butyric and acetic acids. 16S rRNA gene sequencing analysis showed that PSI promoted the relative abundances of Bifidobacteria, Lactobacillus, Faecalibacterium, as well as Prevotella generas in the gut. PSII markedly suppressed the relative abundances of Escherichia-Shigella and Bacteroides generas. We speculate that the PSI and PSII play a role through liver-gut axis system. Polysaccharide-peptides metabolize by gut microbiota to produce short-chain fatty acids (SCFAs) and in turn influence liver functions.

Experimental Study of Potential CD8+ Trivalent Synthetic Peptides for Liver Cancer Vaccine Development Using Sprague Dawley Rat Models

Background. Liver cancer (LC) is the most devastating disease affecting a large set of populations in the world. The mortality due to LC is escalating, indicating the lack of effective therapeutic options. Immunotherapeutic agents may play an important role against cancer cells. As immune cells, especially T lymphocytes, which are part of cancer immunology, the design of vaccine candidates for cytotoxic T lymphocytes may be an effective strategy for curing liver cancer. Results. In our study, based on an immunoinformatics approach, we predicted potential T cell epitopes of MHC class I molecules using integrated steps of data retrieval, screening of antigenic proteins, functional analysis, peptide synthesis, and experimental in vivo investigations. We predicted the binding affinity of epitopes LLECADDRADLAKY, VSEHRIQDKDGLFY, and EYILSLEELVNGMY of LC membrane-bounded extracellular proteins including butyrophilin-like protein-2 (BTNL2), glypican-3 (GPC3), and serum albumin (ALB), respectively, with MHC class I molecules (allele: HLA-A $\ast$ 01:01). These T cell epitopes rely on the level of their binding energy and antigenic properties. We designed and constructed a trivalent immunogenic model by conjugating these epitopes with linkers to activate cytotoxic T cells. For validation, the nonspecific hematological assays showed a significant rise in the count of white blood cells ( $5\times {10}^9/\text{l}$ ), lymphocytes ( $13\times {10}^9/\text{l}$ ), and granulocytes ( $5\times {10}^9/\text{l}$ ) compared to the control after administration of trivalent peptides. Specific immunoassays including granzyme B and IgG ELISA exhibited the significant concentration of these effector molecules in blood serum, indicating the activity of cytotoxic T cells. Granzyme concentration increased to 1050 pg/ml at the second booster dose compared to the control (95 pg/ml), while the concentration of IgG raised to 6 g/l compared to the control (2 g/l). Conclusion. We concluded that a potential therapeutic trivalent vaccine can activate and modulate the immune system to cure liver cancer on the basis of significant outcomes of specific and nonspecific assays.

Metabolic perturbations in fibrosis disease

Metabolic changes occur in all forms of disease but their impact on fibrosis is a relatively recent area of interest. This review provides an overview of the major metabolic pathways, glycolysis, amino acid metabolism and lipid metabolism, and highlights how they influence fibrosis at a cellular and tissue level, drawing on key discoveries in dermal, renal, pulmonary and hepatic fibrosis. The emerging influence of adipose tissue-derived cytokines is discussed and brings a link between fibrosis and systemic metabolism. To close, the concept of targeting metabolism for fibrotic therapy is reviewed, drawing on lessons from the more established field of cancer metabolism, with an emphasis on important considerations for clinical translation.

Apoptosis of hematopoietic progenitor-derived adipose tissue-resident macrophages contributes to insulin resistance after myocardial infarction

Patients with insulin resistance have high risk of cardiovascular disease such as myocardial infarction (MI). However, it is not known whether MI can initiate or aggravate insulin resistance. We observed that patients with ST-elevation MI and mice with MI had de novo hyperglycemia and features of insulin resistance, respectively. In mouse models of both myocardial and skeletal muscle injury, we observed that the number of visceral adipose tissue (VAT)-resident macrophages decreased because of apoptosis after these distant organ injuries. Patients displayed a similar decrease in VAT-resident macrophage numbers and developed systemic insulin resistance after ST-elevation MI. Loss of VAT-resident macrophages after MI injury led to systemic insulin resistance in non-diabetic mice. Danger signaling-associated protein high mobility group box 1 was released by the dead myocardium after MI in rodents and triggered macrophage apoptosis via Toll-like receptor 4. The VAT-resident macrophage population in the steady state in mice was transcriptomically distinct from macrophages in the brain, skin, kidney, bone marrow, lungs, and liver and was derived from hematopoietic progenitor cells just after birth. Mechanistically, VAT-resident macrophage apoptosis and de novo insulin resistance in mouse models of MI were linked to diminished concentrations of macrophage colony-stimulating factor and adiponectin. Collectively, these findings demonstrate a previously unappreciated role of adipose tissue-resident macrophages in sensing remote organ injury and promoting MI pathogenesis.

Polymorphisms rs55710213 and rs56334587 regulate SCD1 expression by modulating HNF4A binding

The stearoyl-CoA desaturase 1 (SCD1) gene at 10q24.31 encodes the rate limiting enzyme SCD1 that catalyzes the biosynthesis of monounsaturated fatty acids (MUFAs) from saturated fatty acids (SFAs). Dysregulated SCD1 activity has been observed in many human diseases including non-alcoholic fatty liver disease (NAFLD), obesity, hypertension, hyperlipidemia, metabolic syndrome and several types of cancer. HNF4A is a central regulator of glucose and lipid metabolism and previous studies suggested that it is deeply involved in regulating the SCD1 activity in the liver. However, the underlying mechanisms on whether and how SCD1 is regulated by HNF4A have not been explored in detail. In this study, we found that HNF4A regulates SCD1 expression by directly binding to the key regulatory regions in the SCD1 locus. Knocking down of HNF4A significantly downregulated the expression of SCD1. Variants rs55710213 and rs56334587 in intron 5 of SCD1 directly reside in a canonical HNF4A binding site. The GG haplotype of rs55710213 and rs56334587 is associated with decreased SCD1 activity by disrupting the binding of HNF4A, which further decreased the enhancer activity and SCD1 expression. In conclusion, our study demonstrated that SCD1 is directly regulated by HNF4A, which may be helpful in the understanding of the altered metabolic pathways in many diseases associated with dysregulated SCD1 or HNF4A or both.

Adiponectin Alleviates Diet-Induced Inflammation in the Liver by Suppressing MCP-1 Expression and Macrophage Infiltration

Adiponectin is an adipokine that exerts insulin-sensitizing and anti-inflammatory roles in insulin target tissues including liver. While the insulin-sensitizing function of adiponectin has been extensively investigated, the precise mechanism by which adiponectin alleviates diet-induced hepatic inflammation remains elusive. Here, we report that hepatocyte-specific knockout (KO) of the adaptor protein APPL2 enhanced adiponectin sensitivity and prevented mice from developing high-fat diet-induced inflammation, insulin resistance, and glucose intolerance, although it caused fatty liver. The improved anti-inflammatory and insulin-sensitizing effects in the APPL2 hepatocyte-specific KO mice were largely reversed by knocking out adiponectin. Mechanistically, hepatocyte APPL2 deficiency enhances adiponectin signaling in the liver, which blocks TNF-α-stimulated MCP-1 expression via inhibiting the mTORC1 signaling pathway, leading to reduced macrophage infiltration and thus reduced inflammation in the liver. With results taken together, our study uncovers a mechanism underlying the anti-inflammatory role of adiponectin in the liver and reveals the hepatic APPL2-mTORC1-MCP-1 axis as a potential target for treating overnutrition-induced inflammation in the liver.

Genome-wide DNA methylation profiling of high-fat emulsion-induced hyperlipidemia mice intervened by a polysaccharide from Cyclocarya paliurus (Batal) Iljinskaja

Genome-wide DNA methylation was used to study the lipid-lowering effect of Cyclocarya paliurus (Batal) Iljinskaja polysaccharide (CPP). The objective of this study was to investigate the hypolipidemic effects and the potential underlying mechanisms of action of CPP-2 in high-fat emulsion (HFE)-induced mice. The results showed that CPP-2 reduced the level of genome-wide DNA methylation in the liver of HFE-induced mice, which had a lipid-lowering effect by regulating the AMP-activated protein kinase (AMPK) signaling-, fatty acid metabolism-, fatty acid biosynthesis- and adipocytokine signaling pathways. A series of lipid metabolism genes were screened out by conjoint analysis of the Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Hereafter, fatty acid synthase (FAS) and peroxisome proliferators-activated receptor α (PPARα) as target genes were selected to validate the accuracy of the results. The findings demonstrated that CPP-2 might be effective in lowering the lipid content, thereby protecting against HFE-induced hyperlipidemia.

Immunonutritional Bioactives from Chenopodium quinoa and Salvia hispanica L. Flour Positively Modulate Insulin Resistance and Preserve Alterations in Peripheral Myeloid Population

Innate immunity plays a determinant role in high fat diet (HFD)-induced insulin resistance. This study compares the effects of immunonutritional bioactives from Chenopodium quinoa (WQ) or Salvia hispanica L. (Ch) when used to partially replace wheat flour (WB) into bread formulations. These flours were chosen to condition starch and lipid content in the products as well as because their immunonutritional activity. To be administered with different bread formulations, HFD-fed C57BL/6J mice were distributed in different groups: (i) wild type, (ii) displaying inherited disturbances in glucose homeostasis, and (iii) displaying dietary iron-mediated impairment of the innate immune TLR4/TRAM/TRIF pathway. We analyze the effects of the products on glycaemia and insulin resistance (HOMA-IR), plasmatic triglycerides, intestinal and hepatic gene expression and variations of myeloid (MY), and lymphoid (LY) cells population in peripheral blood. Our results show that feeding animals with WQ and Ch formulations influenced the expression of lipogenic and coronary risk markers, thus attaining a better control of hepatic lipid accumulation. WQ and Ch products also improved glucose homeostasis compared to WB, normalizing the HOMA-IR in animals with an altered glucose and lipid metabolism. These positive effects were associated with positive variations in the peripheral myeloid cells population.

Removal of Epididymal Visceral Adipose Tissue Prevents Obesity-Induced Multi-organ Insulin Resistance in Male Mice

Obesity is associated with insulin resistance, an important risk factor of type 2 diabetes, atherogenic dyslipidemia, and nonalcoholic fatty liver disease. The major purpose of this study was to test hypothesize that prophylactic removal of epididymal visceral adipose tissue (VAT) prevents obesity-induced multi-organ (liver, skeletal muscle, adipose tissue) insulin resistance. Accordingly, we surgically removed epididymal VAT pads from adult C57BL/6J mice and evaluated in vivo and cellular metabolic pathways involved in glucose and lipid metabolism following chronic high-fat diet (HFD) feeding. We found that VAT removal decreases HFD-induced body weight gain while increasing subcutaneous adipose tissue (SAT) mass. Strikingly, VAT removal prevents obesity-induced insulin resistance and hyperinsulinemia and markedly enhances insulin-stimulated AKT-phosphorylation at serine-473 (Ser473) and threonine-308 (Thr308) sites in SAT, liver, and skeletal muscle. VAT removal leads to decreases in plasma lipid concentrations and hepatic triglyceride (TG) content. In addition, VAT removal increases circulating adiponectin, a key insulin-sensitizing adipokine, whereas it decreases circulating interleukin 6, a pro-inflammatory adipokine. Consistent with these findings, VAT removal increases adenosine monophosphate-activated protein kinase C phosphorylation, a major downstream target of adiponectin signaling. Data obtained from RNA sequencing suggest that VAT removal prevents obesity-induced oxidative stress and inflammation in liver and SAT, respectively. Taken together, these findings highlight the metabolic benefits and possible action mechanisms of prophylactic VAT removal on obesity-induced insulin resistance and hepatosteatosis. Our results also provide important insight into understanding the extraordinary capability of adipose tissue to influence whole-body glucose and lipid metabolism as an active endocrine organ.

The mTORC1 complex in pre-osteoblasts regulates whole-body energy metabolism independently of osteocalcin

Overnutrition causes hyperactivation of mTORC1-dependent negative feedback loops leading to the downregulation of insulin signaling and development of insulin resistance. In osteoblasts (OBs), insulin signaling plays a crucial role in the control of systemic glucose homeostasis. We utilized mice with conditional deletion of Rptor to investigate how the loss of mTORC1 function in OB affects glucose metabolism under normal and overnutrition dietary states. Compared to the controls, chow-fed Rptor_ob^−/− mice had substantially less fat mass and exhibited adipocyte hyperplasia. Remarkably, upon feeding with high-fat diet, mice with pre- and post-natal deletion of Rptor in OBs were protected from diet-induced obesity and exhibited improved glucose metabolism with lower fasting glucose and insulin levels, increased glucose tolerance and insulin sensitivity. This leanness and resistance to weight gain was not attributable to changes in food intake, physical activity or lipid absorption but instead was due to increased energy expenditure and greater whole-body substrate flexibility. RNA-seq revealed an increase in glycolysis and skeletal insulin signaling pathways, which correlated with the potentiation of insulin signaling and increased insulin-dependent glucose uptake in Rptor-knockout osteoblasts. Collectively, these findings point to a critical role for the mTORC1 complex in the skeletal regulation of whole-body glucose metabolism and the skeletal development of insulin resistance.

A stem cell based in vitro model of NAFLD enables the analysis of patient specific individual metabolic adaptations in response to a high fat diet and AdipoRon interference

Non-alcoholic fatty liver disease (NAFLD) is a multifactorial disease. Its development and progression depend on genetically predisposed susceptibility of the patient towards several ‘hits’ that induce fat storage first and later inflammation and fibrosis. Here, we differentiated induced pluripotent stem cells (iPSCs) derived from four distinct donors with varying disease stages into hepatocyte like cells (HLCs) and determined fat storage as well as metabolic adaptations after stimulations with oleic acid. We could recapitulate the complex networks that control lipid and glucose metabolism and we identified distinct gene expression profiles related to the steatosis phenotype of the donor. In an attempt to reverse the steatotic phenotype, cells were treated with the small molecule AdipoRon, a synthetic analogue of adiponectin. Although the responses varied between cells lines, they suggest a general influence of AdipoRon on metabolism, transport, immune system, cell stress and signalling.

Summary: A stem cell based in vitro model of NAFLD recapitulates regulatory networks and suggests a steatosis associated phenotype. AdipoRon treatment influences metabolism, immune system, cell stress and signalling.

Oral administration of potato peel extract affects serum blood metabolites, liver function and ameliorating oxidative stress induced in rabbits exposed to cold stress

This study investigated the effect of potato peel extract (PPE), orally administrated to rabbits, on serum blood metabolites and ameliorating oxidative stress induced by cold stress under Egyptian winter conditions. Twenty-four bucks grouped into three treatments (8 animals per group) were used for the experiment. The animals received 1.5 ml of water orally, containing 0 (PPE0), 25 (PPE25) or 50 (PPE50) mg PPE/kg live weight. Bucks were randomly assigned into three homogenous equal groups according to the level of PPE. Treatments were applied to each animal every two days over a period of three months including one month as an adaptation period. At the 8th week of the experiment, blood samples were collected from each buck and at the end of the experiment, bucks were slaughtered, and some organs were collected and weighed. The PPE improved (p < 0.05) blood total protein, albumin, globulin and glucose. The blood concentration of total lipid, cholesterol, triglyceride, low density lipoprotein and very low-density lipoprotein (were increased (p < 0.02) in PPE rabbits. Furthermore, PPE extract doses decreased (p < 0.001) oxidant thiobarbituric reactive substance (TBARS) in both blood and liver. Other liver and blood antioxidant system enzymes such as catalase, glutathione peroxidase, and superoxide dismutase were improved (p < 0.005) by PPE supplementation. Overall, oral administration of PPE up to 50 mg/kg live weight can have positive effects on rabbit health under cold stress.

Remarkable metabolic reorganization and altered metabolic requirements in frog metamorphic climax

Background

Metamorphic climax is the crucial stage of amphibian metamorphosis responsible for the morphological and functional changes necessary for transition to a terrestrial habitat. This developmental period is sensitive to environmental changes and pollution. Understanding its metabolic basis and requirements is significant for ecological and toxicological research. Rana omeimontis tadpoles are a useful model for investigating this stage as their liver is involved in both metabolic regulation and fat storage.

Results

We used a combined approach of transcriptomics and metabolomics to study the metabolic reorganization during natural and T3-driven metamorphic climax in the liver and tail of Rana omeimontis tadpoles. The metabolic flux from the apoptotic tail replaced hepatic fat storage as metabolic fuel, resulting in increased hepatic amino acid and fat levels. In the liver, amino acid catabolism (transamination and urea cycle) was upregulated along with energy metabolism (TCA cycle and oxidative phosphorylation), while the carbohydrate and lipid catabolism (glycolysis, pentose phosphate pathway (PPP), and β-oxidation) decreased. The hepatic glycogen phosphorylation and gluconeogenesis were upregulated, and the carbohydrate flux was used for synthesis of glycan units (e.g., UDP-glucuronate). In the tail, glycolysis, β-oxidation, and transamination were all downregulated, accompanied by synchronous downregulation of energy production and consumption. Glycogenolysis was maintained in the tail, and the carbohydrate flux likely flowed into both PPP and the synthesis of glycan units (e.g., UDP-glucuronate and UDP-glucosamine). Fatty acid elongation and desaturation, as well as the synthesis of bioactive lipid (e.g., prostaglandins) were encouraged in the tail during metamorphic climax. Protein synthesis was downregulated in both the liver and tail. The significance of these metabolic adjustments and their potential regulation mechanism are discussed.

Conclusion

The energic strategy and anabolic requirements during metamorphic climax were revealed at the molecular level. Amino acid made an increased contribution to energy metabolism during metamorphic climax. Carbohydrate anabolism was essential for the body construction of the froglets. The tail was critical in anabolism including synthesizing bioactive metabolites. These findings increase our understanding of amphibian metamorphosis and provide background information for ecological, evolutionary, conservation, and developmental studies of amphibians.

Exercise augments the modulatory effects of vitamin E on pre-diabetes-induced aortopathy: a potential role of adiponectin

Background: We tested the hypothesis that vitamin E may protect against pre-diabetes-induced aortic injury (aortopathy), and exercise can augment the action of vitamin E.Material and methods: Rats were either fed with a high fat and fructose diet (HFD) (model group) or a standard laboratory chow (control group) for 15 weeks before being sacrificed. The three protective groups were treated with vitamin E (HFD + Vit E), swimming exercises (HFD + Ex), and vitamin E plus swimming exercises (HFD + VitE + Ex), respectively.Results: Aortopathy was developed in the model group as demonstrated by substantial tissue ultrastructural alterations, which were partially protected by vitamin E and effectively protected with vitamin E plus swim exercise. Also, swimming exercises significantly (p < .05) increased the modulatory effects of vitamin E on dyslipidemia, insulin resistance, blood pressure, oxidative stress, inflammation, leptin, and adiponectin, except coagulation and thrombosis.Conclusions: Swim exercise augments the protective effects of vitamin E in a pre-diabetic animal model.

Adiponectin: Role in Physiology and Pathophysiology

Adiponectin, an adipokine secreted by adipocytes, is a well-known homeostatic factor for regulating glucose levels, lipid metabolism, and insulin sensitivity through its anti-inflammatory, anti-fibrotic, and antioxidant effects. All these metabolic processes are mediated via two adiponectin receptors, AdipoR1 and AdipoR2. In addition, adiponectin is one of the hormones with the highest plasma concentrations. Weight loss or caloric restriction leads to increasing adiponectin levels, and this increase is associated with increased insulin sensitivity. Therefore, the adiponectin pathway can play a crucial role in the development of drugs to treat type 2 diabetes mellitus and other obesity-related diseases affected by insulin resistance like cancers or cardiovascular diseases. Adiponectin appears to increase insulin sensitivity by improving glucose and lipid metabolisms. The objective of this review is to analyze current knowledge concerning adiponectin and, in particular, its role in physiology and pathophysiology.

Peroxisome Proliferator-Activated Receptors and Their Novel Ligands as Candidates for the Treatment of Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is a major health issue worldwide, frequently associated with obesity and type 2 diabetes. Steatosis is the initial stage of the disease, which is characterized by lipid accumulation in hepatocytes, which can progress to non-alcoholic steatohepatitis (NASH) with inflammation and various levels of fibrosis that further increase the risk of developing cirrhosis and hepatocellular carcinoma. The pathogenesis of NAFLD is influenced by interactions between genetic and environmental factors and involves several biological processes in multiple organs. No effective therapy is currently available for the treatment of NAFLD. Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors that regulate many functions that are disturbed in NAFLD, including glucose and lipid metabolism, as well as inflammation. Thus, they represent relevant clinical targets for NAFLD. In this review, we describe the determinants and mechanisms underlying the pathogenesis of NAFLD, its progression and complications, as well as the current therapeutic strategies that are employed. We also focus on the complementary and distinct roles of PPAR isotypes in many biological processes and on the effects of first-generation PPAR agonists. Finally, we review novel and safe PPAR agonists with improved efficacy and their potential use in the treatment of NAFLD.

Changes in expression of genes related to glucose metabolism in liver and skeletal muscle of rats exposed to acute hypoxia

The aim of this study was to determine changes in gene expression associated with glucose metabolism in the liver and soleus muscles of rats exposed to hypoxia to improve work capacity under high altitude conditions. Rats were divided into normobaric normoxia (control) and normobaric hypoxia (hypoxia) groups (n = 7 each), and the hypoxia group was exposed to 10.5% oxygen for 90 min. Glucose metabolism-related gene expression was examined by real-time polymerase chain reaction. In the liver, the expression levels of the glucose utilization-related genes solute carrier family 2 member 1, glucokinase, and liver-type phosphofructokinase and the gluconeogenesis-related gene phosphoenolpyruvate carboxykinase 1 (Pck1) were significantly increased upon hypoxic exposure. In contrast, gene expression in the soleus was unchanged, with the exception of Pck1. The results suggest that under hypoxia, both glucose utilization and gluconeogenesis are accelerated in the liver, and liver glycogen is degraded to maintain blood glucose level.

5-Hydroxytryptophan Suppresses the Abdominal Fat Deposit and Is Beneficial to the Intestinal Immune Function in Broilers

Background

Serotonin (5-HT), a monoaminergic neurotransmitter, involves in the regulation of many physiological functions. In the present study, the effects of 5-hydroxytryptophan (5-HTP), the precursor of 5-HT, on lipid metabolism and intestinal immune function in broiler chickens were investigated in chickens.

Methods

Two hundred broilers were divided randomly into two groups and fed separately with a corn-soybean basal diet (CD) or the basal diet supplemented with 0.2% 5-HTP.

Results

The results showed that 5-HTP reduced (P < 0.05) feed intake and the abdominal fat pad weight. 5-HTP treatment tended to upregulate the mRNA level of adiponectin receptor 1 (ADP1R) and ADP2R in abdominal fat but had no significant influence on their protein levels (P > 0.05). In 5-HTP-chickens, lipopolysaccharide exposure decreased secretory immunoglobulin A (sIgA) concentrations in serum and the duodenal contents. Expression of mRNA encoding interleukin (IL), tumor necrosis factor-α (TNF-α), and transforming growth factor-β (TGF-β) decreased after 5-HTP treatment; however, LPS increased expression significantly in 5-HTP-treated chickens compared with CD chickens. In 5-HTP-chickens, the phosphorylation of mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) were reduced, but the phosphorylation of ribosomal p70S6 kinase (p70S6K) was increased in the duodenum.

Conclusion

In summary, the result suggests that dietary 5-HTP supplementation reduces accumulation of abdominal fat and is beneficial to intestinal immune function.

Effects of chronic cadmium exposure at food limitation-relevant levels on energy metabolism in mice

Cadmium (Cd) exposure has been implicated in the perturbation of energy metabolism and the development of cardiometabolic disease, but disease predisposition from chronic low-dose Cd exposure remains unclear. This study employed a mouse model to investigate the toxic effects of chronic Cd exposure at food limitation-relevant levels on energy metabolism and the associated liver and gut microbiome functions. Results showed that the Cd exposure induced the perturbation of energy metabolism in mice, evidenced by the alteration of various metabolites associated with the phosphorogen (adenosine triphosphate-creatine phosphate) system, tricarboxylic acid cycle, and lipid metabolism, as well as the increase of the cardiometabolic risk factor, triglyceride. Moreover, both liver and gut microbiome underwent marked structural/histological and functional alterations, prone to the onset of cardiometabolic disease following the Cd exposure. Certain hepatic transcription factors and gut microbes, specifically PPARα, SREBP1c, HNF4A and the Clostridiales_vadinBB60_group, were identified to be highly correlated with altered urinary metabolites, revealing potential toxicological interactions between the liver and gut microbiome, and energy metabolism. Our findings provide new insights into the progression of metabolic diseases induced by Cd exposure. We also propose a stricter Cd limitation in future food safety standards.

Regulation of adiponectin on lipid metabolism in large yellow croaker (Larimichthys crocea)

Adiponectin (APN), an adipose tissue-derived hormone, plays a key role in regulating energy metabolism in mammals. However, its physiological roles in teleosts remain poorly understood. In the present study, the apn gene was cloned from large yellow croaker, which was mainly expressed in the adipose, muscle and liver. Further studies showed that adaptor protein phosphotyrosine interaction PH domain and leucine zipper 1 (APPL1) was localized in the cytoplasm near the cell membrane and was directly bounded to adiponectin receptors (AdipoRs). Meanwhile, APN played a crucial role in lipid metabolism of primary muscle cells by promoting the synthesis, oxidation and transport of fatty acids, and the promoting effects were blocked by knockdown of appl1 and AdipoRs. Furthermore, the activation/inhibition of peroxisome proliferators activated receptor γ (PPARγ) enhanced/suppressed the APN-mediated lipid metabolism. Overall, results showed that APN mediated lipid metabolism through AdipoRs-APPL1 activated PPARγ and further regulated the synthesis, oxidation and transport of FA. This study will facilitate the investigation of APN functions in lipid metabolism and energy homeostasis and reveal the evolution of lipids utilization and energy homeostasis in vertebrates.

Adipose Tissue Distribution, Inflammation and Its Metabolic Consequences, Including Diabetes and Cardiovascular Disease

Adipose tissue plays essential roles in maintaining lipid and glucose homeostasis. To date several types of adipose tissue have been identified, namely white, brown, and beige, that reside in various specific anatomical locations throughout the body. The cellular composition, secretome, and location of these adipose depots define their function in health and metabolic disease. In obesity, adipose tissue becomes dysfunctional, promoting a pro-inflammatory, hyperlipidemic and insulin resistant environment that contributes to type 2 diabetes mellitus (T2DM). Concurrently, similar features that result from adipose tissue dysfunction also promote cardiovascular disease (CVD) by mechanisms that can be augmented by T2DM. The mechanisms by which dysfunctional adipose tissue simultaneously promote T2DM and CVD, focusing on adipose tissue depot-specific adipokines, inflammatory profiles, and metabolism, will be the focus of this review. The impact that various T2DM and CVD treatment strategies have on adipose tissue function and body weight also will be discussed.

Leptin as a Key Player in Insulin Resistance of Liver Cirrhosis? A Cross-Sectional Study in Liver Transplant Candidates

Insulin resistance is associated with increased risk of death and liver transplantation in the cirrhotic population, independent of disease aetiology. However, factors accounting for insulin resistance in the context of cirrhosis are incompletely understood. This study aimed to investigate the association between adiponectin and leptin with insulin resistance in cirrhotic patients and to assess the influence of disease severity on insulin resistance and metabolic status. This cross-sectional study included 126 non-diabetic cirrhotic transplant candidates. The homeostasis model assessment 2 model was used to determine the insulin resistance index, and fasting adiponectin, leptin, insulin, c-peptide, glucose, HbA1c, and lipid profiles were analysed. Insulin resistance was detected in 83% of subjects and associated with increased leptin, fasting plasma glucose and body mass index, and lower triglyceride levels. Logistic regression analysis identified leptin and triglycerides as independent predictors of insulin resistance (OR 1.247, 95% CI 1.076-1.447, p = 0.003; OR 0.357, 95% CI 0.137-0.917, p = 0.032.). Leptin levels remained unchanged, whereas adiponectin levels increased (p < 0.001) with disease progression, and inversely correlated with HbA1c (ρ = -0.349, p < 0.001). Our results indicate that leptin resistance, as indicated by elevated leptin levels, can be regarded as a contributing factor to insulin resistance in cirrhotic patients, whereas triglycerides elicited a weak protective effect. Progressively increasing adiponectin levels elicited a positive effect on glucose homeostasis, but not insulin sensitivity across disease stages.

Nonalcoholic Fatty Liver Disease in Adults: Current Concepts in Etiology, Outcomes, and Management

Nonalcoholic fatty liver disease (NAFLD) is a spectrum of disease, extending from simple steatosis to inflammation and fibrosis with a significant risk for the development of cirrhosis. It is highly prevalent and is associated with significant adverse outcomes both through liver-specific morbidity and mortality but, perhaps more important, through adverse cardiovascular and metabolic outcomes. It is closely associated with type 2 diabetes and obesity, and both of these conditions drive progressive disease toward the more advanced stages. The mechanisms that govern hepatic lipid accumulation and the predisposition to inflammation and fibrosis are still not fully understood but reflect a complex interplay between metabolic target tissues including adipose and skeletal muscle, and immune and inflammatory cells. The ability to make an accurate assessment of disease stage (that relates to clinical outcome) can also be challenging. While liver biopsy is still regarded as the gold-standard investigative tool, there is an extensive literature on the search for novel noninvasive biomarkers and imaging modalities that aim to accurately reflect the stage of underlying disease. Finally, although no therapies are currently licensed for the treatment of NAFLD, there are interventions that appear to have proven efficacy in randomized controlled trials as well as an extensive emerging therapeutic landscape of new agents that target many of the fundamental pathophysiological processes that drive NAFLD. It is highly likely that over the next few years, new treatments with a specific license for the treatment of NAFLD will become available.

Administration of ginger and/or thyme has ameliorative effects on liver and kidney functions of V-line rabbits: Histological and biochemical studies

This study was conducted to evaluate the effect of Zingiber officinale and Thymus vulgaris aqueous extracts as a natural antioxidant on liver and kidney functions and antioxidant status of growing rabbits. A total of 24 V-line male rabbits, 3 months old, 1.465 ± 0.12 kg average body weight (BW) were used in a complete randomized design. The rabbits were weighed individually and assigned randomly to four groups (6 animals/each). The first group (G1) was taken fresh water and served as control, rabbits of the second group (G2) were taken 100 mg/kg BW in drinking water of the Z. officinale aqueous extract daily. The third group (G3) was taken 50 mg/kg BW in drinking water of the T. vulgaris aqueous extract daily and the fourth group (G4) was taken 100 mg/kg BW of the Z. officinale aqueous extract plus 50 mg/kg BW of the T. vulgaris aqueous extract in drinking water daily. The oral administration of ginger and/or thyme aqueous extracts increased (p < .001) serum protein profile compared with control group. Moreover, results of group 2 showed significant (p < .001) decrease in cholesterol, triglyceride and very low-density lipoprotein cholesterol compared with group 3 and 4. Serum urea, uric acid and creatinine levels were significantly (p < .001) decreased in treated groups compared with control group. Oral administration of ginger and/or thyme aqueous extracts to growing rabbits increased (p < .001) total antioxidant capacity and glutathione content and the activity of superoxide dismutase, catalase and glutathione-S-transferase compared with the control group. In conclusion, the current study showed that oral administration of ginger and thyme aqueous extracts to growing rabbits showed no adverse effects on liver and kidney function parameters, histological structures and improved antioxidant status.

AdipoRon prevents myostatin-induced upregulation of fatty acid synthesis and downregulation of insulin activity in a mouse hepatocyte line

Liver diseases such as non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are characterized by excess hepatic accumulation of lipid droplets and triglycerides which are associated with defective insulin action. Myostatin (Mstn) and adiponectin, secreted by muscle cells and adipocytes, respectively, play important roles in regulating insulin signaling and energy metabolism. The mechanisms underlying the actions of Mstn and adiponectin remain largely unknown. Moreover, the interactions between Mstn and adiponectin in regulating gene expression critical for fatty acid metabolism and insulin action in hepatocytes have not been investigated. The effects of Mstn and AdipoRon, a synthetic adiponectin receptor agonist that is orally active, alone or in combination, on hepatic gene expression and function was investigated. While Mstn increased fatty acid (FA) accumulation and desensitized cellular responses to insulin, AdipoRon protected against Mstn-induced defects in hepatic gene expression and function. In addition, these effects of Mstn were associated with reduced AMPK and PPARα activities which were reversed by AdipoRon. Finally, AdipoRon was able to prevent Mstn-induced activation of the Smad2/3 pathway. These data suggest crosstalk between Mstn-induced Smad2/3 and adiponectin-induced AMPK/PPARα pathways, which may play important roles in the regulation of hepatic gene expression critical for FA metabolism and insulin signaling. In addition, the data suggest that AdipoRon, as an adiponectin receptor agonist, may serve a therapeutic role to reduce the hepatic contribution to the disorders of fat metabolism and insulin action.

Expression Profiling of Inflammatory and Immunological Genes in Collagenous Colitis

BACKGROUND

Collagenous colitis [CC] is a common idiopathic cause of chronic watery diarrhoea. We investigated its pathogenesis by means of gene expression analysis.

METHODS

We analysed the expression of genes implicated in immunological and inflammatory pathways in paired colonic biopsies of histologically involved and uninvolved mucosa from five patients with histologically patchy CC, in pooled colonic biopsies of eight other patients with diffuse CC, and in pooled biopsies of eight normal controls. Analyses were performed with the Nanostring nCounter system. Expression ratios were generated and confirmed by quantitative reverse transcription PCR.

RESULTS

CC mucosa was characterized by enhanced expression of nitric oxide synthase 2; of matrix metalloproteinases 3 and 9 and tissue inhibitor of metalloproteinase 1, but not transforming growth factor β1; of mediators of T-helper 1 immunity including interleukins 12A [IL12A], 12B, IL12 receptor B1 and interferon γ; of immune mediators of the leukocyte immunoglobulin-like receptor subfamily B; and of multiple T cell cytokines and their receptors. The mitogen-activated protein kinase signalling pathway was unchanged. There were no increases in IL22, IL22RA2 or tumour necrosis factor α, which are reportedly elevated in chronic inflammatory bowel disease. In four of five patients with patchy CC, similar gene expression profiles were observed in histologically involved and uninvolved mucosa.

CONCLUSIONS

CC is characterized by altered expression of a limited repertoire of genes involved in nitric oxide synthesis, extracellular matrix remodelling, T-helper 1 immunity and immune modulation. The abnormal gene expression in patchy CC may be expressed in mucosa with and without histological disease manifestations.

The caffeic acid moiety plays an essential role in attenuating lipid accumulation by chlorogenic acid and its analogues

Chlorogenic acid (5-caffeoylquinic, CA) possesses distinct hypolipidemic properties in vivo and in vitro, yet the structure-activity relationship (SAR) of CA on lipid metabolism remains unknown. To achieve this aim, we designed and synthesized two sets of CA analogues and evaluated their efficacies to prevent oleic acid (OA)-elicited lipid accumulation in HepG2 cells. Blockage of all hydroxyl and carboxyl groups on the quinic acid moiety did not deteriorate the hypolipidemic effect of CA while blockage of all phenolic hydroxyl groups on the caffeic acid moiety abolished the activity of CA. Further replacement of the quinic acid moiety with cyclohexane and modification of individual phenolic hydroxyl groups on the caffeic acid moiety showed that the phenolic-hydroxyl-reserved analogues displayed a more potent hypolipidemic effect than CA, whereas the analogue with no phenolic hydroxyl displayed little effect on the OA-elicited lipid accumulation. In accordance, the modulating effects of CA on the transcription of the lipogenic gene sterol-regulatory element binding protein (SREBP)1c/1a, acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS) and peroxisome proliferator-activated receptor α (PPARα) were also abolished when the phenolic hydroxyl groups on the caffeic acid moiety were blocked. Our results suggest that the phenolic hydroxyl on the caffeic acid moiety is vital for the lipid-lowering activity of CA.

Contribution of Adipose Tissue Inflammation to the Development of Type 2 Diabetes Mellitus

The objective of this comprehensive review is to summarize and discuss the available evidence of how adipose tissue inflammation affects insulin sensitivity and glucose tolerance. Low-grade, chronic adipose tissue inflammation is characterized by infiltration of macrophages and other immune cell populations into adipose tissue, and a shift toward more proinflammatory subtypes of leukocytes. The infiltration of proinflammatory cells in adipose tissue is associated with an increased production of key chemokines such as C-C motif chemokine ligand 2, proinflammatory cytokines including tumor necrosis factor α and interleukins 1β and 6 as well as reduced expression of the key insulin-sensitizing adipokine, adiponectin. In both rodent models and humans, adipose tissue inflammation is consistently associated with excess fat mass and insulin resistance. In humans, associations with insulin resistance are stronger and more consistent for inflammation in visceral as opposed to subcutaneous fat. Further, genetic alterations in mouse models of obesity that reduce adipose tissue inflammation are-almost without exception-associated with improved insulin sensitivity. However, a dissociation between adipose tissue inflammation and insulin resistance can be observed in very few rodent models of obesity as well as in humans following bariatric surgery- or low-calorie-diet-induced weight loss, illustrating that the etiology of insulin resistance is multifactorial. Taken together, adipose tissue inflammation is a key factor in the development of insulin resistance and type 2 diabetes in obesity, along with other factors that likely include inflammation and fat accumulation in other metabolically active tissues. © 2019 American Physiological Society. Compr Physiol 9:1-58, 2019.

Tributyltin reduces the levels of serum adiponectin and activity of AKT and induces metabolic syndrome in male mice

Tributyltin (TBT), a proven environmental obesogen, functions as a nanomolar agonist of the peroxisome proliferator activated receptor-γ (PPARγ). However, the adverse effects of TBT on metabolism are incompletely understood. In this study, male ICR mice were administered TBT (5 and 50 μg·kg^-1 ) by an intraperitoneal injection once every 3 days for 30 days from 28 days of age and bred for another 30 days after the last administration of TBT. We analyzed the effects of these exposures on the fat depot weights, serum lipid profile, serum leptin and adiponectin, hepatic lipid accumulation, and activity of AKT in the liver and skeletal muscle isolated from mice 8 mins after receiving an insulin injection. Pubertal exposure to TBTCl resulted in a higher body weight, increased epididymal and liver fat accumulation, hyperlipidemia, an elevated low-density lipoprotein/high-density lipoprotein ratio, serum adiponectin deficiency, worse glucose tolerance, and lower insulin-dependent AKT phosphorylation in the liver and muscle in mice. These results showed that TBT exposure induced peripheral insulin resistance and metabolic syndrome in mice.

Enterobacter cloacae administration induces hepatic damage and subcutaneous fat accumulation in high-fat diet fed mice

Accumulating evidence indicates that gut microbiota plays a significant role in obesity, insulin resistance and associated liver disorders. Family Enterobacteriaceae and especially Enterobacter cloacae strain B29 have been previously linked to obesity and hepatic damage. The underlying mechanisms, however, remain unclear. Therefore, we comprehensively examined the effects of E. cloacae subsp. cloacae (ATCC® 13047™) administration on host metabolism of mice fed with high-fat diet (HFD). C57BL/6N mice were randomly divided into HFD control, chow control, and E. cloacae treatment groups. The E. cloacae treatment group received live bacterial cells in PBS intragastrically twice a week, every other week for 13 weeks. Both control groups received PBS intragastrically. After the 13-week treatment period, the mice were sacrificed for gene and protein expression and functional analyses. Our results show that E. cloacae administration increased subcutaneous fat mass and the relative proportion of hypertrophic adipocytes. Both subcutaneous and visceral fat had signs of decreased insulin signaling and elevated lipolysis that was reflected in higher serum glycerol levels. In addition, E. cloacae -treated mice had significantly higher hepatic AST and AST/ALT ratio, and their liver histology indicated fibrosis, demonstrating that E. cloacae subsp. cloacae administration promotes hepatic damage in HFD fed mice.