Activation of AdipoR1 with rCTRP9 Preserves BBB Integrity through the APPL1/AMPK/Nrf2 Signaling Pathway in ICH Mice.

BACKGROUND: The disruption of the blood brain barrier (BBB) is the key factor leading to neurological impairment after intracerebral hemorrhage (ICH) injury. Adiponectin receptor 1 (AdipoR1) has an important effect contributing to the integrity of BBB. As a homologue of adiponectin, recombinant C1q/TNF-related protein 9 (rCTRP9) has neuroprotective effect in cerebrovascular diseases. The aim of this study was to investigate the protective effect of AdipoR1 activation with rCTRP9 on BBB integrity after ICH injury and the potential mechanisms. METHODS: 177 male mice were subjected in this study. ICH was induced by injecting collagenase into the right basal ganglia. rCTRP9 was treated intranasally at 1 hour after ICH. Selective siRNA was administered prior to ICH. Western blot, immunofluorescence staining, neurobehavioral tests, and BBB permeability were evaluated. RESULTS: ICH increased the expression of endogenous AdipoR1 and CTRP9. Administration of rCTRP9 ameliorated neurological deficits and reduced the BBB permeability at 24 hours in ICH mice. Furthermore, rCTRP9 promoted the expression of AdipoR1, APPL1, p-AMPK, Nrf2, and tight junctional proteins. The intervention of specific siRNA of AdipoR1, APPL1, and p-AMPK reversed the protective effects of rCTRP9. CONCLUSIONS: Activation of AdipoR1 with rCTRP9 improved neurological functions and preserved BBB integrity through the APPL1/AMPK/Nrf2 signaling pathway in ICH mice. Therefore, CTRP9 could serve as a promising therapeutic method to alleviate BBB injury following ICH in patients.

Human Milk Hormone Intake in the First Month of Life and Physical Growth Outcomes in Preterm Infants.

CONTEXT: Human milk contains hormones that regulate metabolism. Extrauterine growth restriction remains common among preterm infants, but the effect of ingesting milk hormones on preterm infant growth is poorly understood. OBJECTIVE: To quantify associations of longitudinal exposure to leptin, adiponectin, and insulin in milk with physical growth of preterm infants. DESIGN/METHODS: In 50 preterm neonates (median gestational age 29.4 weeks), we sampled maternal milk on day-of-life 7, 14, 21, and 28 and measured hormone levels in whole milk by ELISA. Milk leptin levels were available for a subset of 18 infants. We calculated milk hormone doses by multiplying the hormone level by the milk volume ingested on each day and estimated the area under the curve (AUC) to reflect longitudinal exposure. We analyzed associations of milk hormone exposure with growth outcomes in generalized estimated equations. MAIN OUTCOME MEASURES: Weight gain velocity and z-scores in weight, length, head circumference, and body mass index at 36 weeks' postmenstrual age (PMA). RESULTS: Higher leptin intake was associated with greater weight gain (2.17g/kg/day [95% CI, 1.31, 3.02]) and weight z-score at 36 weeks' PMA (0.30 [0.08, 0.53] higher z-score per tertile). Higher adiponectin intake was associated with greater length z-score (0.41 [0.13, 0.69]), however, this association was nullified after adjustment of protein and calorie intake. Higher adiponectin was associated with smaller head circumference z-score (-0.36 [-0.64, -0.07]). Insulin was not associated with growth outcomes. CONCLUSIONS: Milk leptin and adiponectin exposures may affect growth of preterm infants. The long-term effects of milk hormones warrant further investigation.

Adiponectin ameliorates lung injury induced by intermittent hypoxia through inhibition of ROS-associated pulmonary cell apoptosis.

PURPOSE: Obstructive sleep apnea hypopnea syndrome has been reported to be associated with pulmonary hypertension (PH). Adiponectin (Ad) has many protective roles in the human body, including its function as an anti-inflammatory and an anti-oxidant, as well as its role in preventing insulin resistance and atherosclerosis. This study aimed to investigate the molecular mechanism of chronic intermittent hypoxia (CIH)-induced pulmonary injury and the protective role of Ad in experimental rats. METHODS: Thirty male Sprague-Dawley rats were randomly divided into three groups with 10 rats in each group: normal control (NC) group, CIH group, and CIH + Ad group. Rats in the NC group were kept breathing room air for 12 weeks. Rats in the CIH group were intermittently exposed to a hypoxic environment for 8 h/day for 12 weeks. Rats in the CIH + Ad group received 10 µg Ad twice weekly via intravenous injection. After 12 weeks of CIH exposure, we detected the pulmonary function, pulmonary artery pressure, lung histology, pulmonary cell apoptosis, pulmonary artery endothelial cell apoptosis, mitochondrial membrane potential (MMP), and reactive oxygen species (ROS) level. We also analyzed expression proteins involved in the mitochondria-, endoplasmic reticulum (ER) stress-, and Fas receptor-associated pulmonary apoptosis pathways, as well as the SIRT3/SOD2 pathway. RESULTS: CIH exposure for 12 weeks did not lead to abnormal pulmonary function, PH, or pulmonary artery endothelial cell apoptosis. However, we observed a significant increase in the rate of pulmonary cell apoptosis, the expression of proteins involved in mitochondria-, ER stress-, and Fas receptor-associated pulmonary apoptosis pathways, and the generation of ROS in the CIH group compared with the NC group. In contrast, the MMP and protein expressions of SIRT3/SOD2 pathway were significantly decreased in the CIH group compared with the NC group. Ad supplementation in the CIH + Ad group partially improved these changes induced by CIH. CONCLUSION: Even though CIH did not cause abnormal pulmonary function or PH, early lung injury was detected at the molecular level in rats exposed to CIH. Treatment with Ad ameliorated the pulmonary injury by activating the SIRT3/SOD2 pathway, reducing ROS generation, and inhibiting ROS-associated lung cell apoptosis.

Crosstalk between adipocytes and M2 macrophages compensates for osteopenic phenotype in the Lrp5-deficient mice.

A loss-of-function mutation in the Lrp5 gene in mice leads to a low bone mass disorder due to the inhibition of the canonical Wnt signaling pathway; however, the role of bone marrow microenvironment in mice with this mutation remains unclear. In this study, we evaluated proliferation and osteogenic potential of mouse osteoblasts using the MTT assay and Alizarin red staining. The levels of alkaline phosphatase, tartrate-resistant acid phosphatase, and adiponectin in culture supernatants were measured using the enzyme-linked immunosorbent assay. Osteoclast bone resorbing activity was evaluated by toluidine staining and the number and area of bone resorption pits were determined. We observed increased osteogenesis in osteoblasts co-cultured with the BM-derived myeloid cells compared to the osteoblasts cultured alone. Mice with global Lrp5 deletion had a relatively higher bone density compared to the mice carrying osteoblast/osteocyte-specific Lrp5 deletion. An increased frequency of M2 macrophages and reduced expression of inflammatory cytokines were detected in the myeloid cells derived from the bone marrow of mice with global Lrp5 deletion. Higher adipogenic potential and elevated levels of adiponectin in the global Lrp5 deletion mice contributed to the preferential M2 macrophage polarization. Here, we identified a novel systemic regulatory mechanism of bone formation and degradation in mice with global Lrp5 deletion. This mechanism depends on a crosstalk between the adipocytes and M2 macrophages in the bone marrow and is responsible for partly rescuing osteopenia developed as a result of decreased Wnt signaling.

Adiponectin alleviates liver injury in sepsis rats through AMPK/MTOR pathway.

OBJECTIVE: To investigate the influences of adiponectin (APN) on the liver injury in sepsis rats and to explore whether it exerts a therapeutic effect through the adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway. MATERIALS AND METHODS: A rat model of sepsis was established through cecal ligation and puncture (CLP) (CLP group), and APN treatment group (APN group) and control group were also set. The changes in the liver function-related indicators, serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST), were determined by automatic biochemistry analyzer, and the levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1, and IL-6 were measured via enzyme-linked immunosorbent assay (ELISA). Hematoxylin-eosin (HE) staining was employed to detect liver tissue injury, and the hepatocyte apoptosis and necrosis after intervention with APN were evaluated using in situ fluorescence staining. Moreover, the mRNA expression of APN in liver tissues was detected via quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR), and the expression levels of phosphorylated AMPK and mTOR proteins in liver tissue samples were determined using Western blotting. RESULTS: In terms of changes in liver function-related indicators, the concentrations of ALT and AST were substantially raised in the CLP group, and compared with those in the control group, the concentrations of the two indicators significantly declined in the APN group, showing statistically significant differences (p<0.05). CLP and APN group had evidently higher levels of inflammatory factors than the control group, but their levels in APN group were notably lower than those in the CLP group (p<0.05). It was found through the HE staining that the sepsis rats in CLP group had massive inflammatory cell infiltration, and that the inflammatory cells were remarkably decreased in the APN group after APN treatment. According to the in-situ fluorescence staining detection results, CLP group exhibited a notable increase in the cell apoptosis rate, and APN group had substantially reduced apoptotic cells (p<0.05). The determination results of APN expression revealed that CLP group had a lowered level of APN, and that the level of APN in APN group was markedly higher than that in the control group. Based on the results of Western blotting, the level of phosphorylated AMPK was remarkably elevated, and that of phosphorylated mTOR was lowered in the CLP group compared with those in the control group, while in comparison with CLP group, APN group showed a considerable elevation of phosphorylated AMPK level and a distinct decline in the phosphorylated mTOR level. CONCLUSIONS: APN can activate the AMPK/mTOR pathway and reduce hepatocyte apoptosis to alleviate liver injury in sepsis rats.

Adiponectin Reduces Embryonic Loss Rate and Ameliorates Trophoblast Apoptosis in Early Pregnancy of Mice with Polycystic Ovary Syndrome by Affecting the AMPK/PI3K/Akt/FoxO3a Signaling Pathway.

Reports in recent years have suggested that adiponectin (APN) improves insulin resistance and inhibits apoptosis by activating the AMP-activated protein kinase (AMPK) pathway and the PI3K/Akt signaling pathway after binding to its receptor. This study aims to explore the mechanism by which APN reduces embryo loss rate and trophoblast apoptosis in early pregnancy of mice with polycystic ovary syndrome (PCOS). PCOS mice were subcutaneously injected with APN (10 µg mg kg-1 day-1) on 11 consecutive days from the 3rd day of pregnancy onwards to observe the change of the embryo loss rate of PCOS mice induced by APN. Quantitative real-time PCR and Western blot were used to determine the relative expressions of mRNA and the proteins AMPK, PI3K, and Akt in mouse uterine tissue. At the same time, primary cultured mouse villous trophoblast cells were used to further explore the underlying mechanisms in vitro. APN significantly reduces the pregnancy loss rate of PCOS mice. At the same time, APN increases phosphorylation and mRNA expression levels of AMPK, PI3K, and Akt in PCOS mouse uterine tissue. In addition, trophoblast cells of model mice were treated with APN and inhibitors, and APN was found to reduce trophoblast cell apoptosis by affecting the phosphorylation levels of AMPK, PI3K, Akt, and FoxO3a proteins. APN reduces the embryo loss rate and ameliorates trophoblast apoptosis in PCOS mice by affecting the AMPK/PI3K/AKT/FoxO3a signaling pathway.

Novel insights into adiponectin action in breast cancer: Evidence of its mechanistic effects mediated by ERα expression.

This review describes the multifaceted effects of adiponectin on breast cancer cell signalling, tumour metabolism, and microenvironment. It is largely documented that low adiponectin levels are associated with an increased risk of breast cancer. However, it needs to be still clarified what are the extents of the decrease of local/intra-tumoural adiponectin concentrations, which promote breast tumour malignancy. Most of the anti-proliferative and pro-apoptotic effects induced by adiponectin have been obtained in breast cancer cells not expressing estrogen receptor alpha (ERα). Here, we will highlight recent findings demonstrating the mechanistic effects through which adiponectin is able to fuel genomic and non-genomic estrogen signalling, inhibiting LKB1/AMPK/mTOR/S6K pathway and switching energy balance. Therefore, it emerges that the reduced adiponectin levels in patients with obesity work to sustain tumour growth and progression in ERα-positive breast cancer cells. All this may contribute to remove the misleading paradigm that adiponectin univocally inhibits breast cancer cell growth and progression independently on ERα status. The latter concept, here clearly provided by pre-clinical studies, may have translational relevance adopting adiponectin as a potential therapeutic tool. Indeed, the interfering role of ERα on adiponectin action addresses how a separate assessment of adiponectin treatment needs to be considered in novel therapeutic strategies for ERα-positive and ERα-negative breast cancer.

Effects of Adiponectin on Diastolic Function in Mice Underwent Transverse Aorta Constriction.

Diastolic dysfunction is common in various cardiovascular diseases, which could be affected by adiponectin (APN). Nevertheless, the effects of APN on diastolic dysfunction in pressure overload model induced by transverse aorta constriction (TAC) remain to be further elucidated. Here, we demonstrated that treatment of APN attenuated diastolic dysfunction and cardiac hypertrophy in TAC mice. Notably, APN also improved active relaxation of adult cardiomyocytes, increased N2BA/N2B ratios of titin isoform, and reduced collagen type I to type III ratio and lysyl oxidase (Lox) expressions in the myocardial tissue. Moreover, APN supplementation suppressed TAC-induced oxidative stress. In vitro, inhibition of AMPK by compound C (Cpc) abrogated the effect of APN on modulation of titin isoform shift and the anti-hypertrophic effect of APN on cardiomyocytes induced by AngII. In summary, our findings indicate that APN could attenuate diastolic dysfunction in TAC mice, which are at least partially mediated by AMPK pathway.

Normalisation of circulating adiponectin levels in obese pregnant mice prevents cardiac dysfunction in adult offspring.

BACKGROUND/OBJECTIVES: Adiponectin concentrations are low in obese pregnant women. Restoring normal adiponectin concentrations by infusion in obese pregnant mice prevents placental dysfunction, foetal overgrowth and metabolic syndrome in the offspring. We hypothesised that normalising maternal adiponectin in obese late pregnant dams prevents cardiac dysfunction in the adult offspring. SUBJECTS/METHODS: Pregnant female mice with diet-induced obesity were infused with adiponectin (0.62 µg g-1 day-1, n = 24) or saline (n = 22) over days 14.5-18.5 of pregnancy (term = day 19.5). Control dams ate standard chow and received saline (n = 22). Offspring were studied at 3 and 6 months of age. RESULTS: Maternal obesity impaired ventricular diastolic function, increased cardiomyocyte cross-sectional area and upregulated cardiac brain natriuretic peptide (Nppb) and α-skeletal actin (Acta1) gene expression in adult male offspring, compared to control offspring. In adult female offspring, maternal obesity increased Nppb expression, decreased end-diastolic volume and caused age-dependent diastolic dysfunction but not cardiomyocyte hypertrophy. Maternal obesity also activated cardiac Akt and mechanistic target of rapamycin (mTOR) signalling in male, but not in female, offspring and inhibited cardiac extracellular signal-regulated kinase 1/2 (ERK1/2) in both sexes. Normalising maternal circulating adiponectin concentrations by infusing obese dams with adiponectin prevented offspring diastolic dysfunction and ventricular dilation and normalised cardiac Akt-mTOR signalling irrespective of sex. Maternal adiponectin infusion also reduced cardiac Nppb expression and increased ERK1/2 signalling in offspring of obese dams. Adiponectin infusion did not prevent cardiomyocyte hypertrophy but reduced ventricular wall thickness in male offspring and increased collagen content in female offspring of obese dams, compared to controls. CONCLUSIONS: Low maternal adiponectin levels in obese mice in late pregnancy are mechanistically linked to in utero programming of cardiac dysfunction in their offspring. Interventions enhancing endogenous adiponectin secretion or signalling in obese pregnant women could prevent the development of cardiac dysfunction in their children.

Therapeutic Effect of Topical Adiponectin-Derived Short Peptides Compared with Globular Adiponectin in Experimental Dry Eye and Alkali Burn.

Purpose: To evaluate the efficacy of adiponectin (APN)-derived short peptides (ADPs) 355 compared with globular APN in a mouse model of experimental dry eye (EDE) and corneal alkali burn. Methods: EDE and chemical burn were induced in C57BL/6 mice by desiccating stress and application of NaOH, respectively. Eye drops consisting of 0.01% globular APN, 0.01% ADPs, 0.1% ADPs, or balanced salt solution (BSS) were applied. Tear volume, tear film break-up time, and corneal staining scores were measured. Concentrations of interleukin (IL)-1ß, interferon (IFN)-γ, IL-6, CXCL-9, and CXCL-10 using multiplex immunobead assay were evaluated, and flow cytometry were performed. Corneal epithelial defects and haze degree were analyzed, and enzyme-linked immunosorbent assay for IL-1ß and transforming growth factor (TGF)-ß levels were observed. Results: All treatment groups showed an improvement in clinical parameters and CD4+CCR5+ T cell and CD11b+ cell infiltrations in the conjunctiva (all P < 0.05). Both ADPs groups had significantly decreased concentrations of IL-1ß, IFN-γ, IL-6, CXCL-9, and CXCL-10 in the conjunctiva than the EDE or BSS group. Significantly improved parameters of epithelial defect, degree of haze, and concentrations of IL-1ß and TGF-ß were observed in all treatment groups. However, no significant differences were noted in clinical or experimental parameters among treatment groups. Conclusion: Topical ADPs could effectively improve clinical signs and inflammation of ocular surface in the EDE or alkali burn, and its efficacy and potency were similar to those of globular APN.