Adiponectin Resistance in Obesity: Adiponectin Leptin/Insulin Interaction.

The adiponectin (APN) levels in obesity are negatively correlated with chronic subclinical inflammation markers. The hypertrophic adipocytes cause obesity-linked insulin resistance and metabolic syndrome. Furthermore, macrophage polarization is a key determinant regulating adiponectin receptor (AdipoR1/R2) expression and differential adiponectin-mediated macrophage inflammatory responses in obese individuals. In addition to decrease in adiponectin concentrations, the decline in AdipoR1/R2 messenger ribonucleic acid (mRNA) expression leads to a decrement in adiponectin binding to cell membrane, and this turns into attenuation in the adiponectin effects. This is defined as APN resistance, and it is linked with insulin resistance in high-fat diet-fed subjects. The insulin-resistant group has a significantly higher leptin-to-APN ratio. The leptin-to-APN ratio is more than twofold higher in obese individuals. An increase in expression of AdipoRs restores insulin sensitivity and ß-oxidation of fatty acids via triggering intracellular signal cascades. The ratio of high molecular weight to total APN is defined as the APN sensitivity index (ASI). This index is correlated to insulin sensitivity. Homeostasis model of assessment (HOMA)-APN and HOMA-estimated insulin resistance (HOMA-IR) are the most suitable methods to estimate the metabolic risk in metabolic syndrome. While morbidly obese patients display a significantly higher plasma leptin and soluble (s)E-selectin concentrations, leptin-to-APN ratio, there is a significant negative correlation between leptin-to-APN ratio and sP-selectin in obese patients. When comparing the metabolic dysregulated obese group with the metabolically healthy obese group, postprandial triglyceride clearance, insulin resistance, and leptin resistance are significantly delayed following the oral fat tolerance test in the first group. A neuropeptide, Spexin (SPX), is positively correlated with the quantitative insulin sensitivity check index (QUICKI) and APN. APN resistance together with insulin resistance forms a vicious cycle. Despite normal or high APN levels, an impaired post-receptor signaling due to adaptor protein-containing pleckstrin homology domain, phosphotyrosine-binding domain, and leucine zipper motif 1 (APPL1)/APPL2 may alter APN efficiency and activity. However, APPL2 blocks adiponectin signaling through AdipoR1 and AdipoR2 because of the competitive inhibition of APPL1. APPL1, the intracellular binding partner of AdipoRs, is also an important mediator of adiponectin-dependent insulin sensitization. The elevated adiponectin levels with adiponectin resistance are compensatory responses in the condition of an unusual discordance between insulin resistance and APN unresponsiveness. Hypothalamic recombinant adeno-associated virus (rAAV)-leptin (Lep) gene therapy reduces serum APN levels, and it is a more efficient strategy for long-term weight maintenance.

Unraveling the rationale and conducting a comprehensive assessment of AdipoRon (adiponectin receptor agonist) as a candidate drug for diabetic nephropathy and cardiomyopathy prevention and intervention-a systematic review.

Type 2 diabetes mellitus (T2DM) is a widespread chronic disease characterized by persistent hyperglycemia, leading to severe complications such as diabetic cardiomyopathy and nephropathy, significantly affecting patient health and quality of life. The complex mechanisms underlying these complications include chronic inflammation, oxidative stress, and metabolic dysregulation. Diabetic cardiomyopathy, marked by structural and functional heart abnormalities, and diabetic nephropathy, characterized by progressive kidney damage, are major contributors to the increased morbidity and mortality associated with T2DM. AdipoRon, a synthetic adiponectin receptor agonist, has shown potential in preclinical studies for mimicking the beneficial effects of endogenous adiponectin, reducing inflammation and oxidative stress, and improving lipid metabolism and mitochondrial function. This systematic review evaluates the therapeutic potential of AdipoRon, focusing on its impact on diabetic cardiomyopathy and nephropathy. Through a comprehensive literature search and analysis, we highlight AdipoRon's role in ameliorating cardiovascular and renal complications in various animal models and cellular systems. The findings underscore the urgent need for translational clinical studies to validate AdipoRon's efficacy and safety in human populations, aiming to advance this promising therapeutic approach from experimental models to clinical application, potentially offering new hope for improved management of diabetic complications.

Apigenin-6-C-glucoside ameliorates MASLD in rodent models via selective agonism of adiponectin receptor 2.

Adiponectin plays key roles in energy metabolism and ameliorates inflammation, oxidative stress, and mitochondrial dysfunction via its primary receptors, adiponectin receptors -1 and 2 (AdipoR1 and AdipoR2). Systemic depletion of adiponectin causes various metabolic disorders, including MASLD; however adiponectin supplementation is not yet achievable owing to its large size and oligomerization-associated complexities. Small-molecule AdipoR agonists, thus, may provide viable therapeutic options against metabolic disorders. Using a novel luciferase reporter-based assay here, we have identified Apigenin-6-C-glucoside (ACG), but not apigenin, as a specific agonist for the liver-rich AdipoR isoform, AdipoR2 (EC50: 384 pM) with >10000X preference over AdipoR1. Immunoblot analysis in HEK-293 overexpressing AdipoR2 or HepG2 and PLC/PRF/5 liver cell lines revealed rapid AMPK, p38 activation and induction of typical AdipoR targets PGC-1α and PPARα by ACG at a pharmacologically relevant concentration of 100 nM (reported cMax in mouse; 297 nM). ACG-mediated AdipoR2 activation culminated in a favorable modulation of key metabolic events, including decreased inflammation, oxidative stress, mitochondrial dysfunction, de novo lipogenesis, and increased fatty acid ß-oxidation as determined by immunoblotting, QRT-PCR and extracellular flux analysis. AdipoR2 depletion or AMPK/p38 inhibition dampened these effects. The in vitro results were recapitulated in two different murine models of MASLD, where ACG at 10 mg/kg body weight robustly reduced hepatic steatosis, fibrosis, proinflammatory macrophage numbers, and increased hepatic glycogen content. Together, using in vitro experiments and rodent models, we demonstrate a proof-of-concept for AdipoR2 as a therapeutic target for MASLD and provide novel chemicobiological insights for the generation of translation-worthy pharmacological agents.

Regulation and Role of Adiponectin Secretion in Rat Ovarian Granulosa Cells.

Adiponectin is an important adipokine involved in glucose and lipid metabolism, but its secretion and potential role in regulating glucose utilization during ovarian development remains unclear. This study aims to investigate the mechanism and effects of follicle-stimulating hormones (FSHs) on adiponectin secretion and its following impact on glucose transport in the granulosa cells of rat ovaries. A range of experimental techniques were utilized to test our research, including immunoblotting, immunohistochemistry, immunofluorescence, ELISA, histological staining, real-time quantitative PCR, and transcriptome analysis. The immunohistochemistry results indicated that adiponectin was primarily located in the granulosa cells of rat ovaries. In primary granulosa cells cultured in vitro, both Western blot and immunofluorescence assays demonstrated that FSH significantly induced adiponectin secretion within 2 h of incubation, primarily via the PKA signaling pathway rather than the PI3K/AKT pathway. Concurrently, the addition of the AdipoR1/AdipoR2 dual agonist AdipoRon to the culture medium significantly stimulated the protein expression of GLUT1 in rat granulosa cells, resulting in enhanced glucose absorption. Consistent with these in vitro findings, rats injected with eCG (which shares structural and functional similarities with FSH) exhibited significantly increased adiponectin levels in both the ovaries and blood. Moreover, there was a notable elevation in mRNA and protein levels of AdipoRs and GLUTs following eCG administration. Transcriptomic analysis further revealed a positive correlation between the expression of the intraovarian adiponectin system and glucose transporter. The present study represents a novel investigation, demonstrating that FSH stimulates adiponectin secretion in ovarian granulosa cells through the PKA signaling pathway. This mechanism potentially influences glucose transport (GLUT1) and utilization within the ovaries.

Adiponectin-mediated regulation of the adiponectin cascade in cardiovascular disease: Updates.

The endocrine function of white adipose tissue is characterized by the synthesis of one its main hormones: adiponectin. Although the biological role of adiponectin has not been fully defined, clinical and experimental observations have shown that low plasma concentrations of adiponectin participate in the prevalence of insulin resistance and cardiovascular diseases, mainly in obese patients. Adiponectin also exerts its effects on the heart and blood vessels, thereby influencing their physiology. Studying the effects of adiponectin presents some complexities, primarily due to potential cross-interactions and interference with other pathways, such as the AdipoR1/R2 pathways. Under optimal conditions, the activation of the adiponectin cascade may involve signals such as AMPK and PPARα. Interestingly, these pathways may trigger similar responses, such as fatty acid oxidation. Understanding the downstream effectors of these pathways is crucial to comprehend the extent to which adiponectin signaling impacts metabolism. In this review, the aim is to explore the current mechanisms that regulate the adiponectin pathways. Additionally, updates on the major downstream factors involved in adiponectin signaling are provided, specifically in relation to metabolic syndrome and atherosclerosis.

As a matter of fat: Emerging roles of lipid-sensitive E3 ubiquitin ligases.

The dynamic structure and composition of lipid membranes need to be tightly regulated to control the vast array of cellular processes from cell and organelle morphology to protein-protein interactions and signal transduction pathways. To maintain membrane integrity, sense-and-response systems monitor and adjust membrane lipid composition to the ever-changing cellular environment, but only a relatively small number of control systems have been described. Here, we explore the emerging role of the ubiquitin-proteasome system in monitoring and maintaining membrane lipid composition. We focus on the ER-resident RNF145 E3 ubiquitin ligase, its role in regulating adiponectin receptor 2 (ADIPOR2), its lipid hydrolase substrate, and the broader implications for understanding the homeostatic processes that fine-tune cellular membrane composition.

[Cloning of adipor1 and adipor2 genes in Rana dybowskii and its expression pattern upon infection].

Adiponectin receptor 1 (AdipoR1) and Adiponectin receptor 2 (AdipoR2) can bind to adiponectin (AdipoQ) secreted by adipose tissue to participate in various physiological functions of the body. In order to explore the role of AdipoR1 and AdipoR2 in amphibians infected by Aeromonas hydrophila (Ah), the genes adipor1 and adipor2 of Rana dybowskii were cloned by reverse transcription-polymerase chain reaction (RT-PCR) and analyzed by bioinformatics. The tissue expression difference of adipor1 and adipor2 was analyzed by real-time fluorescence quantitative polymerase chain reaction (qRT-PCR), and an inflammatory model of R. dybowskii infected by Ah was constructed. The histopathological changes were observed by hematoxylin-eosin staining (HE staining); the expression profiles of adipor1 and adipor2 after infection were dynamically detected by qRT-PCR and Western blotting. The results show that AdipoR1 and AdipoR2 are cell membrane proteins with seven transmembrane domains. Phylogenetic tree also shows that AdipoR1 and AdipoR2 cluster with the amphibians in the same branch. qRT-PCR and Western blotting results show that adipor1 and adipor2 were up-regulated at different levels of transcription and translation upon Ah infection, but the response time and level were different. It is speculated that AdipoR1 and AdipoR2 participate in the process of bacterial immune response, providing a basis for further exploring the biological functions of AdipoR1 and AdipoR2 in amphibians.

A novel small molecule AdipoR2 agonist ameliorates experimental hepatic steatosis in hamsters and mice.

Adiponectin receptor 2 (AdipoR2) can be activated by its endogenous ligand adiponectin to reduce hepatic steatosis, and is regarded as a therapeutic target for metabolic associated fatty liver disease (MAFLD). This study proposes a novel anthraquinone compound, emodin succinate monoethyl ester (ESME), which activates AdipoR2, inhibits hepatic lipogenesis, promotes fatty acid oxidation, and alleviates experimental hepatic steatosis in hamsters and mice. Molecular docking shows that ESME has strong binding potential with AdipoR2 by forming a arene-arene interaction. AdipoR2 on the cytomembrane of HepG2 cells can be labeled by fluorescent ESME (Cy5-ESME). ESME activates AdipoR2, AMPK and PPARα, and reduces lipid deposition in palmitic acid or oleic acid-induced HepG2 and L02 cells. Suppression of AdipoR2 expression or AMPK activation completely eliminates the effect of ESME on reducing lipid accumulation in hepatocytes. Oral administration of ESME reduces liver lipid production and accumulation, and alleviates hepatic steatosis in hamsters and Apoe-/- mice induced by high-fat diet. Compared with statins and emodin, ESME showed prepotent efficacy and safety in reducing hepatic steatosis and protecting hepatocytes. Furthermore, ESME activates CaMKK2 and LKB1 in liver to activate AMPK and reduce lipogenesis through stimulating AdipoR2. Taken together, ESME reduces hepatic lipid accumulation and alleviates hepatic steatosis by agonizing AdipoR2. ESME is a promising new agent for clinical treatment of MAFLD.

Distinct roles of ADIPOR1 and ADIPOR2: A pan-cancer analysis.

Introduction: AdipoR1 and AdipoR2 proteins, encoded by ADIPOR1 and ADIPOR2 genes respectively, are the receptors of adiponectin secrected by adipose tissue. Increasing studies have identified the vital role of adipose tissue in various diseases, including cancers. Hence, there is an urgent need to explore the roles of AdipoR1 and AdipoR2 in cancers. Methods: We conducted a comprehensive pan-cancer analysis for the roles of AdipoR1 and AdipoR2 via several public databases, including expression differences, prognostic value, and the correlations with tumor microenvironment, epigenetic modification, and drug sensitivity. Results: Both ADIPOR1 and ADIPOR2 genes are dysregulated in most cancers, but their genomic alteration frequencies are low. In addition, they are also correlated with the prognosis of some cancers. Although they are not strongly correlated with tumor mutation burden (TMB) or microsatellite instability (MSI), ADIPOR1/2 genes display a significant association with cancer stemness, tumor immune microenvironment, immune checkpoint genes (especially CD274 and NRP1), and drug sensitivity. Discussion: ADIPOR1 and ADIPOR2 play critical roles in diverse cancers, and it is a potential strategy to treat tumors through targeting ADIPOR1 and ADIPOR2.

Cloning of adipor1 and adipor2 genes in Rana dybowskii and its expression pattern upon infection / 生物工程学报

Adiponectin receptor 1 (AdipoR1) and Adiponectin receptor 2 (AdipoR2) can bind to adiponectin (AdipoQ) secreted by adipose tissue to participate in various physiological functions of the body. In order to explore the role of AdipoR1 and AdipoR2 in amphibians infected by Aeromonas hydrophila (Ah), the genes adipor1 and adipor2 of Rana dybowskii were cloned by reverse transcription-polymerase chain reaction (RT-PCR) and analyzed by bioinformatics. The tissue expression difference of adipor1 and adipor2 was analyzed by real-time fluorescence quantitative polymerase chain reaction (qRT-PCR), and an inflammatory model of R. dybowskii infected by Ah was constructed. The histopathological changes were observed by hematoxylin-eosin staining (HE staining); the expression profiles of adipor1 and adipor2 after infection were dynamically detected by qRT-PCR and Western blotting. The results show that AdipoR1 and AdipoR2 are cell membrane proteins with seven transmembrane domains. Phylogenetic tree also shows that AdipoR1 and AdipoR2 cluster with the amphibians in the same branch. qRT-PCR and Western blotting results show that adipor1 and adipor2 were up-regulated at different levels of transcription and translation upon Ah infection, but the response time and level were different. It is speculated that AdipoR1 and AdipoR2 participate in the process of bacterial immune response, providing a basis for further exploring the biological functions of AdipoR1 and AdipoR2 in amphibians.

Circulating adiponectin levels, expression of adiponectin receptors, and methylation of adiponectin gene promoter in relation to Alzheimer's disease.

BACKGROUND: The role of adiponectin (ADIPOQ) in Alzheimer's disease (AD) has been documented, however, demonstrating controversial results. In this study, we investigated blood serum ADIPOQ levels, methylation of the adiponectin gene promoter, and adiponectin receptors (AdipoR1 and AdipoR2) expression in blood samples isolated from AD patients and healthy controls. METHODS: We performed a case-control study including 248 subjects (98 AD patients and 150 healthy controls); ADIPOQ serum levels, AdipoR1, and AdipoR2 levels in PBMC were measured by ELISA Kits, and ADIPOQ gene methylation was analyzed using methyl-specific PCR. RESULTS: Serum adiponectin levels were threefold higher in the AD group compared to the controls. We have also found a positive correlation between adiponectin and MMSE scores and high-density lipoprotein cholesterol (HDL-C) in AD patients. A significant difference in the proportion of methylation of the CpG sites at - 74 nt of the ADIPOQ gene promoter was detected in AD cases, and the levels of adiponectin in blood serum were significantly higher in methylated samples in the AD group compared to controls. The amount of AdipoR1 was significantly higher among AD subjects, while the expression of AdipoR2 did not vary between AD patients and controls. CONCLUSION: These findings may contribute to a deeper understanding of the etiological factors leading to the development of dementia and may serve as a basis for the development of predictive biomarkers of AD.

Greater Body Fatness Is Associated With Higher Protein Expression of LEPR in Breast Tumor Tissues: A Cross-Sectional Analysis in the Women's Circle of Health Study.

Background: The mechanisms underlying the association of overall and central body fatness with poorer breast cancer outcomes remain unclear; altered gene and/or protein expression of the adipokines and their receptors in breast tumors might play a role. Methods: In a sample of Black and White women with primary invasive breast cancer, we investigated associations of body mass index (BMI), waist circumference, hip circumference, waist-to-hip ratio (WHR), fat mass index (FMI), and percent body fat with protein expression (log-transformed, n = 722) and gene expression (log2-transformed, n = 148) of leptin (LEP), leptin receptor (LEPR), adiponectin (ADIPOQ), and adiponectin receptors 1 and 2 (ADIPOR1, ADIPOR2). Multivariable linear models, adjusting for race, menopausal status, and estrogen receptor status, were used to assess these associations, with Bonferroni correction for multiple comparisons. Results: In multivariable models, we found that increasing BMI (ß = 0.0529, 95% CI: 0.0151, 0.0906) and FMI (ß = 0.0832, 95% CI: 0.0268, 0.1397) were associated with higher LEP gene expression, corresponding to 34.5% and 38.3% increases in LEP gene expression for a standard deviation (SD) increase in BMI and FMI, respectively. Increasing BMI (ß = 0.0028, 95% CI: 0.0011, 0.0045), waist circumference (ß = 0.0013, 95% CI: 0.0005, 0.0022), hip circumference (ß = 0.0015, 95% CI: 0.0007, 0.0024), and FMI (ß = 0.0041, 95% CI: 0.0015, 0.0067) were associated with higher LEPR protein expression. These associations equate to 16.8%, 17.6%, 17.7%, 17.2% increases in LEPR protein expression for a 1-SD increase in BMI, waist circumference, hip circumference, and FMI, respectively. Further, these associations were stronger among White and postmenopausal women and ER+ cases; formal tests of interaction yielded evidence of effect modification by race. No associations of body fatness with LEP protein expression, LEPR gene expression, or protein or gene expression of ADIPOQ, ADIPOR1, and ADIPOR2 were found. Conclusions: These findings support an association of increased body fatness - beyond overall body size measured using BMI - with higher LEP gene expression and higher LEPR protein expression in breast tumor tissues. Clarifying the impact of adiposity-related adipokine and adipokine receptor expression in breast tumors on long-term breast cancer outcomes is a critical next step.

Overexpressing circ_0000831 is sufficient to inhibit neuroinflammation and vertigo in cerebral ischemia through a miR-16-5p-dependent mechanism.

Circular RNAs (circRNAs) hold potential as stroke-related biomarkers due to involvement in various pathophysiological processes associated with cerebral ischemia and stability in peripheral blood. Differentially expressed circulating circRNAs were identified by preliminary sequencing analysis, through which we identified underexpressed circ_0000831 in ischemic stroke (IS). Validation was performed in peripheral blood of IS patients by quantitative polymerase chain reaction. Microglia was exposed to oxygen-glucose deprivation (OGD), where polarization phenotypes and inflammation were assessed. Middle cerebral artery occlusion was performed in mice to mimic ischemic stroke-induced vertigo, where cerebral blood flow, neurological deficits, vertigo degree, infarct area, inflammation and cell apoptosis were assayed in response to ectopic expression and knockdown of circ_0000831, miR-16-5p, and AdipoR2. Mechanically, circ_0000831 bound to miR-16-5p and downregulated miR-16-5p, and AdipoR2 was targeted by miR-16-5p and increased PPARγ expression in microglia. Furthermore, circ_0000831, AdipoR2, or PPARγ overexpression or miR-16-5p inhibition alleviated neuroinflammation, vertigo, neurological deficit, and cell apoptosis in MCAO mice. Consistently, circ_0000831, AdipoR2, or PPARγ upregulation or miR-16-5p downregulation diminished apoptosis and inflammation of OGD-induced microglia. Consequently, these findings pinpoint the circ_0000831/miR-16-5p/AdipoR2 axis as an essential signaling pathway during ischemia stroke. Thus, the circRNA circ_0000831 may work as a possible target for novel treatment in patients with ischemic stroke.

Adiponectin Influences FGF2 in the Developing Porcine Corpus Luteum.

Luteal angiogenesis is regulated by pro-angiogenic hormones including fibroblast growth factor 2 (FGF2) and angiopoietin 1 (Ang1), which are regulated by the adipokine leptin during development. Another adipokine, adiponectin, exhibits an inverse relationship with leptin and has been identified in the CL. Therefore, it is hypothesized that adiponectin will influence pro-angiogenic hormones in the developing porcine CL. Crossbred sows were randomly allocated to one of two days of the estrous cycle, day 5 (D5; n = 4) or day 7 (D7; n = 5) for CL collection. Tissue was processed for immunohistochemical localization of adiponectin receptor 2 (AdipoR2), gene expression of FGF2, Ang1, leptin, AdipoR2, and cell culture for adiponectin treatment. The expression of AdipoR2 tended (p = 0.09) to be higher in D7 lutea and was more prevalently localized to the cell surface of large and small luteal cells than in D5 tissue. Adiponectin influenced (p ≤ 0.05) FGF2, leptin, and AdipoR2 gene expression relative to the dose and day (D5 or D7). Collectively, the evidence supports the supposition that adiponectin influences angiogenic factors in the developing CL.

Identification of miRNAs involved in liver injury induced by chronic exposure to cadmium.

To elaborate the molecular mechanism underlying the hepatotoxicity induced by chronic exposure to cadmium (Cd), a mouse model with hepatocyte-specific deletion of Ppp2r1a (encoding protein phosphatase 2 A Aα subunit, PP2A Aα) gene was used to investigate the effect of cadmium exposure on liver injury. The wild type littermates (WT) and PP2A Aα-/- mice (KO) were treated with cadmium chloride (CdCl2) at concentrations of 0 mg/L, 10 mg/L, 100 mg/L in drinking water for 3, 6 and 9 months (KO mice only for 9 months), respectively. The pathological findings were characterized by progressive inflammation, steatosis, and liver fibrosis upon treatment of CdCl2 in a dose-response and time-dependent manner. Notably, PP2A Aα depletion leads to a more profound liver injury induced by CdCl2 treatment. The transcriptome analysis in livers of KO mice revealed 20 differentially expressed microRNAs (miRNAs) appeared in both 3- and 9-month. Particularly, the alterations of miR-34a-5p, miR-345-5p, and miR-30e-5p expressions were implicated in the development of liver disease and correlated with the degree of liver injury induced by cadmium treatment. Further analysis indicated that miR-34a-5p, miR-345-5p, and miR-30e-5p might be involved in CdCl2-induced liver injury, in part by dysregulation of lipid metabolism and inflammation. The in vitro studies showed that miR-34a-5p was involved in regulation of CdCl2-induced cytotoxicity through directly targeted adiponectin receptor 2 (AdipoR2) mRNA. Taken together, we identified that specific miRNAs were implicated in hepatotoxicity induced by chronic exposure to CdCl2. These findings also provide new insight into the role of PP2A in regulation of miRNAs-mediated liver injury.

Enhanced Immunomodulation, Anti-Apoptosis, and Improved Tear Dynamics of (PEG)-BHD1028, a Novel Adiponectin Receptor Agonist Peptide, for Treating Dry Eye Disease.

Dry eye disease (DED) is characterized by impaired tear dynamics, leading to complex pathophysiological conditions. (PEG)-BHD1028, a peptide agonist to AdipoRs, was evaluated as a potential therapeutic agent for DED based on the reported physiological function of adiponectin, including anti-inflammation and epithelial protection. Therapeutic effects of (PEG)-BHD1028 were evaluated in experimentally induced EDE with 0.001%, 0.01%, and 0.1% (PEG)-BHD1028 in mice and 0.1%, 0.2%, and 0.4% in rabbits for 10 days. In the rabbit study, 0.05% cyclosporine was also tested as a comparator. The results from the mouse study revealed significant improvement in tear volumes, tear breakup time (TBUT), inflammation, and corneal severity score (CSS) within 10 days at all (PEG)-BHD1028 concentrations. In the rabbit study, the tear volume and TBUT significantly increased in (PEG)-BHD1028 groups compared with vehicle and 0.05% cyclosporine groups. The CSS, apoptosis rate, and corneal thickness of all (PEG)-BHD1028 and 0.05% cyclosporine groups were significantly improved relative to the vehicle group. The immune cell counts of 0.2% and 0.4% (PEG)-BHD1028 treated groups were significantly lower than those of the vehicle group. These results represent the potential of (PEG)-BHD1028 as an effective therapeutic agent for DED.

The CTRP3-AdipoR2 Axis Regulates the Development of Experimental Autoimmune Encephalomyelitis by Suppressing Th17 Cell Differentiation.

C1q/TNF-related proteins (CTRP) including CTRP3 are a group of secreted proteins which have a complement C1q-like domain in common, and play versatile roles in lipid metabolism, inflammation, tumor metastasis and bone metabolism. Previously, we showed that the expression of C1qtnf3, encoding CTRP3, is highly augmented in joints of autoimmune arthritis models and CTRP3-deficiency exacerbates collagen-induced arthritis in mice. However, the mechanisms how CTRP3-deficiency exacerbates arthritis still remain to be elucidated. In this study, we showed that CTRP3 was highly expressed in Th17 cell, a key player for the development of autoimmune diseases, and Th17 cell differentiation was augmented in C1qtnf3-/- mice. Th17 cell differentiation, but not Th1 cell differentiation, was suppressed by CTRP3 and this suppression was abolished by the treatment with a receptor antagonist against AdipoR2, but not AdipoR1, associated with suppression of Rorc and Stat3 expression. Furthermore, AdipoR1 and AdipoR2 agonist, AdipoRon suppressed Th17 cell differentiation via AdipoR2, but not AdipoR1. The development of myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis was enhanced in C1qtnf3-/- mice associated with increase of Th17 cell population. CTRP3 inhibited MOG-induced IL-17 production from T cells by affecting both T cells and dendritic cells. These results show that CTRP3 is an endogenous regulator of Th17 differentiation, suggesting that the CTRP3-AdipoR2 axis is a good target for the treatment of Th17 cell-mediated diseases.

Effects of Obesity on Adiponectin System Skin Expression in Dogs: A Comparative Study.

Obesity is an important health issue in dogs since it influences a plethora of associated pathologies, including dermatological disorders. Considering the scarcity of information in pets, this work aimed to evaluate the localization and expression of adiponectin (ADIPOQ) and its two receptors (ADIPOR1 and ADIPOR2) in the skin of 10 obese dogs, compared with serum ADIPOQ level. Through immunohistochemistry, ADIPOQ and ADIPOR2 were observed in the adipose tissue, sweat and sebaceous glands, endothelium, and some connective cells. Both receptors were observed in the epidermis and the hair follicles, other than in the sweat and sebaceous glands. Real-time PCR evidenced that the ADIPOQ and ADIPOR2 transcripts were expressed 5.4-fold (p < 0.01) and 2.3-fold less (p < 0.01), respectively, in obese than in normal weight dogs, while ADIPOR1 expression did not change. Obese dogs showed lower serum ADIPOQ levels than the normal weight group. Accordingly, ADIPOQ and ADIPOR2 expression in the skin appear negatively correlated with obesity in the same way as the serum ADIPOQ level. These findings evidence that ADIPOQ system changes in the skin of obese dogs and suggest that the ADIPOQ effect on the skin is at least in part regulated by the reduced expression of ADIPOR2.

Crosstalk between AdipoR1/AdipoR2 and Nrf2/HO-1 signal pathways activated by ß-caryophyllene suppressed the compound 48/80 induced pseudo-allergic reactions.

Mast cell activation is initiated by two signalling pathways: immunoglobulin E (IgE)-dependent and IgE-independent pathway. It is reported that the IgE-independent type or pseudo-allergy pathway gets activated by G-protein-dependent activation of the mast cell. Recently, adiponectin (APN) receptors, AdipoR1, and AdipoR2 have been identified as G-protein-coupled receptors (GPCRs). Interestingly, APN replenishment is reported to activate the Nrf2/HO-1 signalling axis. However, no study has been performed interlinking the role of APN and the Nrf2/HO-1 signalling axis in pseudo-allergic reaction. In the present study, we evaluated the anti-pseudo-allergic effects of ß-caryophyllene, an FDA-approved food additive, in activating AdipoR1/AdipoR2 and Nrf2/HO-1 axis signalling pathway. Compound 48/80 (C48/80)-induced systemic and cutaneous anaphylaxis-like shock in BALB/c mice was performed to assess the efficacy of ß-caryophyllene (BCP). To assess the effect of BCP in anaphylactic hypotension, mean arterial pressure was measured in Wistar rats. Inhibitory properties of BCP in mast cell degranulation were estimated in rat peritoneal mast cells (RPMCs). ELISA was performed to estimate interleukin (IL)-6, tumour necrosis factor (TNF), IL-1ß, IgE, ovalbumin (OVA)-IgE and APN and western blotting for protein expression of Nrf2/HO-1 and AdipoR1-AdipoR2. BCP dose-dependently inhibited systemic and cutaneous anaphylaxis-like shock induced by C48/80. BCP dose-dependently inhibited the mast cell degranulation followed by inhibition of histamine release. Also BCP dose-dependently activated the Nrf2/HO-1 and AdipoR1-AdipoR2 signalling axis pathway. Moreover, BCP reversed the drop in blood pressure when the haemodynamic parameters were accessed. Our findings suggest that BCP is a potent AdipoR1/AdipoR2-Nrf2/HO-1 axis pathway agonist that may suppress the IgE-independent pathway towards allergic response to secretagogues.

AdipoR2 inhibits human glioblastoma cell growth through the AMPK/mTOR pathway.

BACKGROUND: AdipoR2, which belongs to the seven-transmembrane-domain receptor family, has been shown to play an important role in the development of human tumours, but the underlying mechanisms are poorly understood. In this study, we found that AdipoR2 expression correlates with glioma grade. In addition, we also investigated the mechanisms behind the antiproliferative effects of AdipoR2 in U251 cells (a human glioma cell line) using colony formation and WST-8 growth assays. METHODS: The U251 cell line was cultured in vitro. Western blotting was used to detect the expression of relevant proteins. Quantitative RT-PCR was used to detect AdipoR1 and AdipoR2 expression. Flow cytometry was used to detect cell cycle assay results. The gene expression profiles of glioma samples from the CGGA database were analysed by MATLAB and GSEA software. RESULTS: The AMPK/mTOR pathway plays a central role in the regulation of cell proliferation, differentiation and migration and may promote tumorigenesis. Therefore, we can control cancer progression by modulating the AMPK/mTOR pathway. However, there is no information on the relationship between AdipoR and AMPK/mTOR in central nervous system tumours such as GBM. In this study. We found 648 upregulated genes and 436 downregulated genes correlated with AdipoR2 expression in 158 glioma samples. GSEA suggested that AdipoR2 is a cell cycle-associated gene. The results of the flow cytometry analysis indicated that AdipoR2 induced G0/G1 cell cycle arrest in U251 cells. Furthermore, we identified the AMPK/mTOR signalling axis to be involved in AdipoR2-induced cell cycle arrest. CONCLUSIONS: Our results suggest that AdipoR2 may represent a novel endogenous negative regulator of GBM cell proliferation. These findings also suggest that AdipoR2 may be a promising therapeutic target in GBM patients.