Adiponectin Protein Expression Research Articles

SLC25A28 Overexpression Promotes Adipogenesis by Reducing ATGL.

Adipose tissue dysfunction is seen among obese and type 2 diabetic individuals. Adipocyte proliferation and hypertrophy are the root causes of adipose tissue expansion. Solute carrier family 25 member 28 (SLC25A28) is an iron transporter in the inner mitochondrial membrane. This study is aimed at validating the involvement of SLC25A28 in adipose accumulation by tail vein injection of adenovirus (Ad)-SLC25A28 and Ad-green fluorescent protein viral particles into C57BL/6J mice. After 16 weeks, the body weight of the mice was measured. Subsequently, morphological analysis was performed to establish a high-fat diet (HFD)-induced model. SLC25A28 overexpression accelerated lipid accumulation in white and brown adipose tissue (BAT), enhanced body weight, reduced serum triglyceride (TG), and impaired serum glucose tolerance. The protein expression level of lipogenesis, lipolysis, and serum adipose secretion hormone was evaluated by western blotting. The results showed that adipose TG lipase (ATGL) protein expression was reduced significantly in white and BAT after overexpression SLC25A28 compared to the control group. Moreover, SLC25A28 overexpression inhibited the BAT formation by downregulating UCP-1 and the mitochondrial biosynthesis marker PGC-1α. Serum adiponectin protein expression was unregulated, which was consistent with the expression in inguinal white adipose tissue (iWAT). Remarkably, serum fibroblast growth factor (FGF21) protein expression was negatively related to the expansion of adipose tissue after administrated by Ad-SLC25A28. Data from the current study indicate that SLC25A28 overexpression promotes diet-induced obesity and accelerates lipid accumulation by regulating hormone secretion and inhibiting lipolysis in adipose tissue.

Experimental periodontitis induced hypoadiponectinemia by IRE1α-mediated endoplasmic reticulum stress in adipocytes

BackgroudHypoadiponectinemia is the important cause of insulin resistance. Recent studies have shown that periodontitis is associated with hypoadiponectinemia. The purpose of this study was to investigate the effect of periodontitis-induced endoplasmic reticulum stress (ERS) in visceral adipocytes on hypoadiponectinemia.MethodsRat periodontitis models were established by local ligation with silk around the bilateral maxillary second molars. Porphyromonas gingivalis-lipopolysaccharid (P.g-LPS) was also used to stimulate the visceral adipocytes in vitro. The protein expression levels of glucose regulated protein 78 (GRP78), inositol-requiring protein 1α (IRE1α), protein kinase RNA-like ER kinase (PERK), activating transcription factor 6 (ATF6) and adiponectin were detected. IRE1α lentiviruses were transfected into visceral adipocytes in vitro, and an IRE1α inhibitor (KIRA6) was injected in epididymal adipose tissue of rats to detect and verify the effect of ERS on adiponectin expression in visceral adipocytes in vivo.ResultsHypoadiponectinemia was observed in periodontitis rat, and the expression levels of ERS key proteins GRP78 and the phosphorylation levels of IRE1α (p-IRE1α)/IRE1α in visceral adipocytes were increased, while the expression levels of adiponectin protein were decreased. After KIRA6 injection into epididymal adipose tissue of rats with periodontitis, adiponectin levels in visceral adipocytes increased, and serum adiponectin levels recovered to a certain extent. The protein expression levels of GRP78 and p-IRE1α/IRE1α were increased and adiponectin protein expression was decreased in P.g-LPS-induced visceral adipocytes. Overexpression of IRE1α further inhibited adiponectin expression in P.g-LPS-stimulated visceral adipocytes, and conversely, IRE1α inhibition restored adiponectin expression.ConclusionsOur findings suggest that periodontitis induces ERS in visceral adipocytes leading to hypoadiponectinemia. IRE1α is a key protein regulating adiponectin expression in visceral adipocytes.

Cimifugin inhibits adipogenesis and TNF-α-induced insulin resistance in 3T3-L1 cells.

To investigate the effects of cimifugin on adipogenesis and tumor necrosis factor (TNF-α)-induced insulin resistance (IR) and inflammation in 3T3-L1 adipocytes. 3T3-L1 adipocytes were treated with 3-isobutyl-1-methyl-xanthine, dexamethasone, and insulin or cimifugin and then Oil Red O staining and intracellular triglyceride content detection were performed to assess adipogenesis. Subsequently, after cimifugin treatment, TNF-α was used to induce IR and inflammation. The results showed that cimifugin reduced intracellular lipids accumulation of 3T3-L1 adipocytes. Cimifugin improved IR of 3T3-L1 adipocytes induced by TNF-α, as reflected in decreased adiponectin, GLUT-4, and IRS-1 mRNA and protein expression. Moreover, cimifugin reduced TNF-α-induced pro-inflammatory factors production and phospho-P65 expression, and MAPK pathway activation in the 3T3-L1 adipocytes. These findings suggested that cimifugin might be useful for the prevention and therapy of obesity-related IR and inflammation.

Nicotine Impairs the Anti-Contractile Function of Perivascular Adipose Tissue by Inhibiting the PPARγ-Adiponectin-AdipoR1 Axis.

Nicotine is an addictive compound found in cigarette smoke that leads to vascular dysfunction and cardiovascular diseases. Perivascular adipose tissue (PVAT) exerts an anti-contractile effect on the underlying vasculature through the production of adipokines, such as adiponectin, which acts on adiponectin receptors 1 (adipoR1) to cause vasorelaxation. Peroxisome proliferator-activated receptor gamma (PPARγ) is a transcription factor that regulates adiponectin gene expression and PVAT development. This study aimed to determine the effect of nicotine on the anti-contractile function of PVAT via the PPARγ-adiponectin-adipoR1 axis. Male Sprague Dawley rats were divided into a control group (given normal saline), a nicotine group (given 0.8 mg/kg of nicotine), and a nicotine + PPARγ agonist group (given nicotine and 5 mg/kg of telmisartan). Thoracic aorta PVAT was harvested after 21 days of treatment. The results showed that nicotine reduced the anti-contractile effect of PVAT on the underlying thoracic aorta. Nicotine also decreased the gene and protein expression of PPARγ, adiponectin, and adipoR1 in PVAT. Treatment with telmisartan restored the anti-contractile effect of PVAT and increased the gene and protein expression of PPARγ, adiponectin, and adipoR1 in PVAT. In conclusion, nicotine attenuates the anti-contractile function of PVAT through inhibition of the PPARγ-adiponectin-adipoR1 axis.

Monocyte Chemoattractant Protein-1-Supplemented Plasma Enhances Adiponectin and Adipogenesis-Related Gene Expression.

Increasing adipogenesis has been explored to treat metabolic diseases and atherosclerosis through the release of adiponectin. The effects and mechanism of platelet-rich plasma treatment on fat graft survival and adipogenesis have not been clarified. Here, we aimed to study the effects of monocyte chemoattractant protein-1 (MCP-1)-supplemented plasma on adipogenesis-related gene expression and adiponectin levels. Stromal vascular fractions (SVFs) purified from the inguinal adipose tissue of obese and diabetic (Leprdb/db) mice were treated with plasma from control (Lepr+/+) mice supplemented with 10 or 50 ng of MCP-1. The expression of adiponectin and interleukin-33 (IL-33) mRNA in adipose tissue was increased in Leprdb/db mice, whereas control (Lepr+/+) plasma reduced expression of IL-33 mRNA as well as peroxisome proliferator-activated receptor gamma (PPARγ), pJNK, and pNF-κB protein, and increased the expression of IL-10 mRNA in SVFs of Leprdb/db mice. MCP-1-supplemented control plasma increased the expression of adiponectin, CCAAT-enhancer-binding protein α (C/EBPα), dipeptidyl peptidase 4 (DPP4), IL-33, and PDGFα mRNA and the expression of adiponectin protein as well as PPARγ of SVFs and the expression of PPARγ mRNA in adipose tissue macrophages (ATMs). Injection of MCP-1-supplemented plasma into adipose tissue of Leprdb/db mice increased the expression of IL-33 and Col3a1 mRNA in SVFs and IL-33, FABP4, PDGFα, PPARγ and PPARγ2 of ATMs, protein expression of adiponectin and PPARγ of SVFs, and plasma adiponectin levels, as well as DPP4 activity. In conclusion, our results demonstrate that control plasma decreases adipogenesis and increases IL-10, and decreases IL-33, pJNK, and pNF-κB in adipose tissue. MCP-1-supplemented plasma enhances adipogenesis-related gene expression in SVFs and adiponectin levels, which may be mediated through an increase of IL-33 and PPARγ. Thus, our findings suggest that MCP-1-supplemented plasma represents a novel therapy to stimulate local adipogenesis and systemic adiponectin levels.

Different ratios of DHA/EPA reverses insulin resistance by improving adipocyte dysfunction and lipid disorders in HFD-induced IR mice.

Objective: Insulin resistance (IR) is linked to the development of diabetes, non-alcoholic fatty liver disease (NAFLD), and cardiovascular disease (CVDs). Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) from fish oils (FOs) were used to investigate their potential in high-fat diet (HFD)-induced IR mice under different ratios. Methods: A total of 84 male C57BL/6J (6 weeks old) mice were fed with HFD containing 45% kcal from fat for 16 weeks to establish the IR model. The IR mice were then fed with HFD or HFD + 4% DHA/EPA with different ratios (3 : 1, 1.5 : 1, 1 : 1, 1 : 1.5, 1 : 3, respectively) for another 12 weeks. During the experiment, the CON group (n = 12) was set to feed with a basic diet containing 10% kcal from fat. Results: HFD feeding for 16 weeks reduced insulin sensitivity and accelerated hypertrophy of white adipose tissue (WAT). Different ratios of DHA/EPA except for 1 : 1 decreased the HOMA-IR index, average area of adipocytes, and serum MDA, but increased the protein expression of PI3K. All ratios of DHA/EPA increased the protein expression of IRS-1, GLUT4, and adiponectin. Moreover, dietary DHA/EPA changed serum fatty acid (FA) composition by increasing the serum concentration of n-3 PUFAs. DHA/EPA supplements also improved serum lipid profiles (TG/TC/LDL-c/HDL-c, FFA) and reduced the hepatic steatosis area. Conclusions: The results indicate that an appropriate higher ratio of DHA (1.5 : 1) in DHA/EPA supplementation is recommended for IR prevention.

Edible and medicinal mushrooms (Pleurotus ostreatus, Ustilago maydis, Ganoderma lucidum) reduce endoplasmic reticulum stress and inflammation in adipose tissue of obese Wistar rats fed with a high fat plus saccharose diet.

Obesity is an increasing global public health problem. A strategy to treat obesity is the use of functional foods. Edible and medicinal mushrooms contain diverse bioactive compounds showing important antihyperlipidemic, antioxidant, and prebiotic properties. We analysed the effects of adding (10%) of Pleurotus ostreatus (Po, basidiomata), Ganoderma lucidum (Gl, basidiomata), or Ustilago maydis (Um, galls), milled, to a high fat plus saccharose diet (HFD + S) for 6 months in a model of obesity with Wistar rats. We assessed weight gain, body composition, lipid parameters, endoplasmic reticulum stress (proteins and inflammatory markers: BiP, XBP-1, JNK, p-JNK, TNF-α), and adiponectin in subcutaneous adipose tissue (SAT). The consumption of edible and medicinal mushrooms decreased weight gain (-17.2-30.1%) and fat mass (-23.7-43.1%), maintained fat-free mass, reduced levels of serum biochemical parameters (TC: -40.1-44.1%, TG: -37.7-51.6%, LDL-C: -64.5-71.1%), and prevented adipocyte hypertrophy (-30.9-36.9%) and collagen deposition (-70.9-73.7%) in SAT. Compared with the HFD + S group, mushroom consumption by Wistar rats significantly reduced the expression of proteins associated with endoplasmic reticulum stress and inflammation (BiP: -72.2-88.2%; XBP-1: -71.5-81.8%; JNK: -71.2-90.0%; p-JNK: -37.3-81.0%; TNF-α: -80.7-91.5%), whereas significantly increased adiponectin protein expression (246.4-654.2%) in SAT. These effects outperformed those obtained through the commercial lipid-lowering drug atorvastatin, contributing synergistically to prevent further obesity-related dysfunctions, such as insulin resistance derived from inflammation and ER stress in adipose tissue. Bioactive compounds from edible, functional and medicinal mushrooms represent new emerging therapies for obesity treatments using natural products.

Genetic and Functional Effects of Adiponectin in Type 2 Diabetes Mellitus Development.

Diabetes mellitus (DM) is a common chronic metabolic disease, and the C57BLKsJ-db/db mice are good animal models for type 2 diabetes mellitus (T2DM). In this study, Western blotting and immunohistochemistry (IHC) were employed to examine the protein expression of adiponectin in the liver tissues of T2DM mice with different disease courses (4, 16, and 32 weeks). Adiponectin expression reduced in the liver tissues of T2DM mice in different disease courses. The genotypic and allelic frequencies of the adiponectin gene rs1063538 and rs2241766 single nucleotide polymorphisms (SNPs) in a Taiwanese population (570 T2DM patients and 1700 controls) were investigated. Based on the genetic distribution of the rs2241766 locus, the distribution frequency of the T allele in the T2DM group (72.8%) was higher than in the control group (68.8%). Individuals carrying the G allele had a 0.82-fold greater risk of developing T2DM than individuals carrying the T allele. Differences were evident in the genotypic and allelic distributions (p < 0.05). Enzyme-linked immunosorbent assay (ELISA) was used to measure changes in serum adiponectin protein concentrations in the healthy population and in patients with T2DM. Serum adiponectin concentration in patients with T2DM was lower than in the control group. In summary, adiponectin was determined to be a T2DM susceptibility gene and may be involved in T2DM progression.

HDL AND ITS SUBPOPULATION (HDL2 AND HDL3) PROMOTE CHOLESTEROL TRANSPORTERS EXPRESSION AND ATTENUATES INFLAMMATION IN 3T3-L1 MATURE ADIPOCYTES INDUCED BY TUMOR NECROSIS FACTOR ALPHA

Obesity activates inflammation causing dysfunction of adipocytes. Increasing high-density lipoprotein (HDL) levels in obesity may be beneficial in overcoming this effect. However, not much data is available on the effects of HDL and its subpopulations in inflamed adipocytes. The objective of this study was to investigate the effects of total HDL (tHDL) and the comparison between its subpopulations (HDL2 & HDL3) on protein and gene expression of cholesterol transporters, inflammation, and adipokines in TNF-α stimulated 3T3-L1 mature adipocytes. TNFα alone had lower adiponectin and higher protein and gene expression of IL-6 and NF-ĸβ (p65) compared to unstimulated adipocytes and these effects were attenuated by HDLs especially HDL3 (in most of the biomarkers). HDL and its subpopulation had higher cholesterol transporters expression in 3T3-L1 mature adipocytes induced by TNF-α compared to unstimulated cells. Increment of cholesterol transporters expression by HDL leads to reduce secretion of inflammatory markers [IL-6 & NF-kB (p65)] and visfatin and increases adiponectin secretion in the inflamed mature adipocytes. HDL exhibits beyond its reverse cholesterol transporter property by exhibiting anti-inflammatory effects thru the deactivation of NF-ĸβ (p65). This may contribute to reducing the progression of obesity-related complications.

Adiponectin Intervention to Regulate Betatrophin Expression, Attenuate Insulin Resistance and Enhance Glucose Metabolism in Mice and Its Response to Exercise.

Aims: Adiponectin stimulates mitochondrial biogenesis through peroxisome proliferator-activated receptor-coactivator1α (PGC-1α), a major regulator of mitochondrial biogenesis, and its effect on the genesis of insulin resistance is organ-specific. Expressed predominantly in fat and liver tissues, betatrophin is primarily involved in lipid metabolism, and could be a putative therapeutic target in metabolic syndrome and T2D. We hypothesized that the adiponectin pathway may regulate the production and/or secretion of betatrophin in liver. We aimed to determine whether exercise and adiponectin affect betatrophin to improve insulin resistance in mice. Methods: To investigate this hypothesis, we used wild-type C57BL/6 mice subjected to a high-fat diet, an exercise regimen, and i.p. injection of recombinant mouse adiponectin (Acrp30), and adiponectin knockout (Adipoq−/−) mice (C57BL/6 background) subjected to i.p. injection of Acrp30. Results: In Adipoq–/– mice, betatrophin levels in the plasma and liver were upregulated. In mice, plasma and liver betatrophin levels were significantly upregulated following a high-fat diet. Exercise and i.p. Acrp30 downregulated betatrophin levels and increased adiponectin mRNA and protein expression in the plasma and liver. The trend of change in PGC-1α and betatrophin levels in the liver was consistent. Conclusions/interpretation: Exercise reverses pathogenic changes in adiponectin and betatrophin levels in insulin-resistant mice. Exercise increased adiponectin levels and reduced betatrophin levels. Furthermore, exercise reduced betatrophin levels via adiponectin, which modulated the LKB1/AMPK/PGC-1α signaling axis but was not solely dependent on it for exerting its effects.

009 Adiponectin-derived pentapeptide ameliorates psoriasiform skin inflammation by suppressing IL-17 production in γδT cells

Adiponectin, a hormone secreted from adipocytes, is closely associated with psoriasis and suppresses psoriasiform inflammation. Recently, a small-sized transdermally deliverable 5-mer peptide (GLYYF; P5) was discovered as a potential adiponectin receptor 1 agonist. This study aims at confirming the reduction of adiponectin protein level in the human psoriasis skin and investigating whether functional adiponectin replenishment by topical P5 application improves psoriasiform skin inflammation. We examined the adiponectin protein expression in the skin of individuals with psoriasis and normal skin.

Electroacupuncture improves follicular development and metabolism and regulates the expression of adiponectin, AMPK and ACC in an obese rat model of polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) is a common endocrine disorder characterized by hyperandrogenism and follicular arrest. Electroacupuncture (EA) has been shown to be effective at improving hyperandrogenism and follicular arrest in PCOS; however, its mechanism of action remains to be deciphered. In this study, we investigated whether EA improved follicular development in an obese rat model of PCOS and regulated the expression of adiponectin, AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC). EA was administered at CV3, CV4 and ST40. Changes in body weight, paraovarian fat, estrus cycle, ovarian morphology, levels of related hormones, and glucose and lipid metabolism were evaluated. In addition, protein and mRNA expression of adiponectin, AMPK and ACC was measured. The body weight and paraovarian fat of rats in the EA group were reduced, while estrus cyclicity and ovarian morphology improved. Levels of free fatty acids, triglycerides, total cholesterol and low-density lipoprotein cholesterol were significantly reduced in the EA group, as well as blood glucose levels. Furthermore, levels of testosterone and luteinizing hormone were reduced in the EA group, while estradiol levels were increased. Protein and mRNA expression of adiponectin, AMPKα1 and liver kinase B1 (LKB1) was found to be increased in the EA group, while protein and mRNA expression of ACC were significantly reduced.Conclusion: Our findings suggest that EA improved follicular development and metabolism and regulated expression levels of adiponectin, AMPKα1, LKB1 and ACC in our obese rat model of PCOS.

Adipose tissue alleviates the stress response by releasing adiponectin during laparoscopic surgery in patients with colorectal cancer

Background and objectivesLaparoscopic colorectal surgery causes a lower stress response than open surgery. Adiponectin is mainly derived from adipocytes and has antidiabetic, antioxidative, and anti-inflammatory capabilities. The objective of the present study was to investigate the protein expression of adiponectin in adipose tissue, and the serum levels of adiponectin, oxidative stress markers and proinflammatory factors during laparoscopic colorectal surgery and open surgery periods.MethodsForty patients aged 60 to 80, with American Society of Anesthesiologists (ASA) I ~ II who underwent radical resection of colorectal cancer were recruited to the study. Laparoscopic group and open group included 20 patients each. Mesenteric adipose tissue and venous blood before (T1) and at the end (T2) of surgery were collected to examine adiponectin levels, and venous blood was collected to examine serum levels of oxidative stress related markers (superoxide dismutase (SOD), glutathione (GSH), lipid peroxide (LPO), malondialdehyde (MDA)), and inflammation-related factors (interleukin (IL)-1β, interleukin (IL)-6, tumor necrosis factor-α (TNF-α)).ResultsProtein and serum levels of adiponectin were analyzed, and adiponectin levels were significantly increased at T2 than T1 in the laparoscopic surgery, while adiponectin levels were significantly higher in the laparoscopic surgery than in the open surgery at T2. In addition, the serum levels of SOD and GSH were significantly higher in the laparoscopic surgery than in open surgery at T2. However, the serum levels of LPO, TNF-α, IL-1β, and IL-6 were significantly lower in the laparoscopic group than in open group at T2.ConclusionLaparoscopic surgery induced higher levels of adiponectin in both adipose tissue and the bloodstream. Oxidative stress and the inflammatory response were lower during laparoscopic colorectal surgery than during conventional open surgery. These data suggest that adipose tissue may alleviate the stress response during laparoscopic surgery by releasing adiponectin in patients with colorectal cancer.

The locoregional adiponectin and its synergistic antitumor effect with HIF-1α blockade in TSCC.

Adiponectin (APN) is a kind of endogenous anti-tumor adipocytokine, which exerts its function by binding to its receptors (AdipoR1 and AdipoR2). However, hyperadiponectinemia is found in some pathophysiological processes without significant protective effect, which indicates the existence of APN resistance. Here, we aimed to investigate the locoregional expression of APN in tongue squamous cell carcinoma (TSCC) tissues, and to explore the potential regulatory mechanism of APN resistance under hypoxia. Consequently, we found that the protein expression of APN and AdipoR1, but not AdipoR2, was upregulated in the early stage of TSCC and after hypoxic treatment ex vivo and in vitro. Knockdown of HIF-1α decreased the level of APN and AdipoR1, and simultaneously, HIF-1α was identified as transcriptor of the APN. Intriguingly, a regenerative feedback of HIF-1α was unexpectedly detected after application of recombinant globular APN (gAPN), which most likely contributed to the APN resistance. Furthermore, HIF-1α blockade combined with gAPN has a prominent synergistic antitumor effect, which suggested an effective amelioration in APN resistance. In all, our study revealed the possible mechanism of APN resistance under hypoxia and provides a promising strategy of bi-target treatment with APN and HIF-1α for TSCC therapy.

Alteration in Aromatase and Estrogen Receptor Target Gene Expression in Human Benign Mammary Tissue After Bariatric Surgery

Abstract Background: Over 30% of US adults are obese (body mass index (BMI) of ≥ 30 kg/m2). Obesity is considered a significant and modifiable risk factor for ER+ postmenopausal breast cancer (BC). However, the effect on pre-menopausal breast cancer risk is less clear. Bariatric surgery is performed on obese patients who have a BMI of >35. It has been associated with reduced risk of BC, but the mechanisms behind this are unknown. Studies in obese patients have revealed multiple changes in the physiology of the microenvironment that contribute to BC development. The molecular changes in the stroma and epithelium from metabolic syndrome, excess inflammation, and ectopic hormone synthesis likely play key role in obesity related BC. Therefore, understanding how we can alter the risk posed will have an impact on decreasing the incidence of BC. We hypothesize that bariatric surgery will reduce the incidence of postmenopausal ER+ BC by reducing estradiol availability and ER activity. Methods: We recruited 30 women undergoing bariatric surgery, who underwent core needle biopsy at the time of surgery and after they had lost 25% of their excess body weight. Changes in hormone concentration by LCMS/MS in serum and breast tissue, protein expression in breast tissue by IHC and the altered gene expression in breast epithelium and stroma by RNA seq were measured. Results: When segregated by menopausal status, Androstenedione (p=0.02), Testosterone (p < 0.0001) and 27-hydroxycholesterol (p=0.017) showed significant reduction in the plasma post-surgery in premenopausal women. There were no significant differences in the hormone levels in the breast tissue and in postmenopausal women post-surgery. We observed that African Americans (AA) were half as likely to show a reduction in tissue concentration compared to Caucasian women. IHC was performed to examine protein expression of Ki67, leptin R, aromatase, CYP27A1, Stat3, adiponectin, CYP27B1 and ER in the breast core biopsy. Aromatase expression (p < 0.0001) was significantly reduced in both the epithelial and stromal compartments. In addition, Stat3 levels (p=0.044) were significantly reduced in the stroma. RNA -seq analysis revealed distinct differentially expressed genes pre and post-surgery. Specifically, genes associated with metabolic process, epithelial development, extracellular space, immune and inflammatory response pathways. Furthermore, known ER target genes TFF1, AGR2 expression were significantly decreased in Caucasian women, but not in AA women, post- surgery. Conclusions: Taken together, these data show that bariatric surgery decreased aromatase expression, some hormones in pre-menopausal women and reduced estrogen availability and ER activity. Further analysis of differentially regulated genes due to bariatric surgery can allow us to explore previously unknown pathways related to breast cancer risk reduction.

L‐Citrulline Decreases LPS‐Induced Inflammation and Oxidative Stress in Newborn Rat Lungs

Introduction Extremely low birth weight infants have immature lungs at birth as well as low levels of anti-inflammatory and antioxidative defences, placing them at high risk of developing bronchopulmonary dysplasia (BPD). Adiponectin (APN) is produced by adipocytes and has potent anti-inflammatory and antioxidative properties, and anti-proliferative effects; APN levels are quite low in premature infants. We showed that exogenous APN markedly attenuated lipopolysaccharide (LPS)-induced lung injury (Ivanovska et al. 2020) in newborn rats. Recombinant APN is not available for human use; however, L-citrulline (L-CIT) increases APN gene expression in adult rats (Joffin et al., 2015) and upregulates expression of peroxisome proliferator-activated receptor-gamma coactivator alpha (PGC-1α). PGC-1α is a master coactivator of genes involved in mitochondrial biogenesis, inflammation and oxidative stress. L-CIT levels are also low in premature infants. Thus, we sought to determine the effect of exogenous L-CIT on LPS-induced changes in protein expression of PGC-1α, APN, APN receptors (AdipoR1/2), cytokines, and superoxide dismutase (SOD) in lung and pulmonary artery smooth muscle cells (PASMC) homogenates, and on LPS-induced changes of intracellular ROS levels in PASMC. Methods in-vivo: Sprague Dawley rat pups were treated with L-CIT (2.5 g/kg) or saline intraperitoneally from postnatal day (PND) 1-5. On PND 5, intra-pharyngeal LPS (5mg/kg) or saline was given to L-CIT (n=4-6) or saline (n=4-6) treated animals; pups were euthanized 24 h after LPS treatment and lungs were removed and processed for western blot. In-vitro: PASMCisolated from PND 4 rats were treated with L-CIT (4 mM/ml), LPS (5μg/ml) and a combination of the two, for 3 h; cells were harvested and processed for protein expression (n=4 replicate experiments). PASMC were assayed for the level of LPS-induced intracellular ROS with fluorescence dye in the presence and absence of blocker for PGC-1α (SR 18292) Results In vivo, L-CIT, in the presence of LPS, increased lung protein expression of APN (1.36-fold), AdipoR1/2 (2-fold), PGC-1α (1.8-fold), phosphorylated AMP-kinase (2.1-fold), SOD1 (2.3-fold), SOD2 (1.7-fold), SOD3 (1.43-fold), and decreased tumor necrosis factor α (1.2-fold), and interleukin-8 (1.28-fold) compared to saline and LPS treated animals (p<0.05 L-CIT+LPS vs saline+LPS for all proteins). In vitro, in the presence of LPS, L-CIT increased PASMC protein expression of PGC-1α (1.55-fold), SOD1 (2-fold), SOD2 (1.57-fold), and SOD3 (2.2-fold) compared to cells only exposed to LPS (p<0.05; L-CIT+LPS vs medium+LPS). L-CIT decreased LPS-induced ROS production in PASMC, an effect that was inhibited in the presence of PGC-1α blocker. Conclusion L-CIT upregulates APN signaling in presence of LPS and decreases LPS-induced lung inflammation and oxidative stress in newborn rats through activation of PGC1-α. The translational significance of these findings warrants further clinical studies of the L-CIT potential preventative/curative benefit in BPD.

Secreted frizzled-related protein 4 promotes brown adipocyte differentiation.

Secreted frizzled-related protein 4 (SFRP4) is a member of the SFRP family that contains a cysteine-rich domain homologous to the putative Wnt-binding site of frizzled proteins. In the present report, the effects of SFRP4 on murine brown adipocyte differentiation were evaluated, which exhibited an intrinsic capacity to differentiate with high efficiency. Brown preadipocytes were isolated from the scapular region of brown adipose tissue, which showed that the overexpression of recombinant active SFRP4 protein at three concentrations (1, 10 and 100 ng/ml) significantly increased the expression of adipocyte differentiation-associated genes (C/EBPα, C/EBPβ, UCP-1, PRDM16, PGC1α and GLUT4) in a dose-dependent manner compared with the control group. Secondly, adiponectin protein expression was significantly inhibited in a dose-independent manner, while leptin was increased in brown adipocytes by incubation with the high concentration (100 ng/ml) of SFRP4. Thirdly, the role of interleukin-1β (IL-1β) was investigated in brown adipocytes and discovered that IL-1β cannot induce SFRP4 mRNA expression in brown adipocytes, similar to human islet cells. These data suggested that SFRP4-treated brown adipocytes represent a valuable in vitro model for the study of adipogenesis and indicated that SFRP4 served various functions during brown adipocyte differentiation.

Adipokine signatures of subcutaneous and visceral abdominal fat in normal-weight and obese women with different metabolic profiles.

IntroductionMetabolic syndrome arises from abnormal adipose function accompanied by insulin resistance. As early factors reflecting/impacting lipid storage dysfunction of adipose tissues, we sought to determine adipokine levels in subcutaneous and visceral adipose tissues (SAT and VAT).Material and methodsGene and protein expression levels of leptin, adiponectin, and resistin were analysed in SAT and VAT of normal-weight and overweight/obese women, subclassified according to insulin resistance index, triglyceride, total, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol levels into metabolically healthy and “at risk” groups.ResultsCompared with normal-weight women, obese women had higher serum leptin levels (p < 0.05), as well as increased leptin gene and protein expression in VAT. Conversely, expression levels of leptin were lower in SAT of obese women, and minor in the SAT of “at risk” groups of women, compared with weight-matched healthy groups. In addition, lower adiponectin levels were detected in SAT of metabolically healthy obese women (p < 0.01), and lower in SAT and VAT (p < 0.05) of “at risk” obese women compared to healthy, obese women. Significant differences in resistin levels were only observed in obese women; resistin gene expression was higher in VAT and SAT of obese, compared to normal-weight women. However, higher gene expression was not consistent with protein expression of resistin.ConclusionsLow adiponectin in both examined adipose tissues and inappropriate leptin expression levels in SAT appear to be important characteristics of obesity-related metabolic syndrome. Intriguingly, this adipokine dysregulation is primary seen in SAT, suggesting that endocrine dysfunction in this abdominal depot may be an early risk sign of metabolic syndrome.

Evaluation of adipokines and inflammatory mediator expression levels in patients with periodontitis and peri-implantitis: a cross-sectional study.

The aim of this study was to analyze the mRNA and protein expression of adiponectin, leptin, visfatin, tumor necrosis factor (TNF)-α, and interleukin (IL)-6 levels in periodontitis and peri-implantitis sites in systemically healthy individuals and to investigate the influence of the presence of current periodontitis on their expression levels in peri-implantitis sites. Soft tissue biopsy samples were collected from 60 systemically healthy patients [15 periodontally healthy patients (group I), 16 patients with periodontitis (group II), 15 patients with peri-implantitis (group III), and 14 patients with peri-implantitis and periodontitis (group IV)]; mRNA expression levels of adiponectin, leptin, visfatin, TNF-α, and IL-6 were measured by quantitative real-time PCR; and their protein levels were assessed by immunohistochemistry. The mRNA expression levels of all biomarkers were significantly higher for group II compared to group I, while significantly higher levels of leptin, TNF-α, and IL-6 were observed in group III in comparison with group I. Group II exhibited significantly higher mRNA expression of adiponectin and TNF-α than group III. Group IV showed significantly higher expression levels of adiponectin, leptin, TNF-α, and IL-6 compared to group III. Regarding the expression of protein levels, which was estimated through quantification of the histoscore, both groups II and III presented higher H-scores than group I for all biomarkers except leptin. The presence of current periodontitis may enhance expression levels of adiponectin, leptin, TNF-α, and IL-6 in peri-implant soft tissue. The presence of periodontitis is an important risk factor for the severity of peri-implant inflammation as well as the onset of peri-implantitis.

Adiponectin treatment improves insulin resistance in mice by regulating the expression of the mitochondrial-derived peptide MOTS-c and its response to exercise via APPL1-SIRT1-PGC-1α.

Adiponectin stimulates mitochondrial biogenesis through peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α), a major regulator of mitochondrial biogenesis. MOTS-c (mitochondrial open reading frame of the 12S rRNA) is a biologically active mitochondrial-derived peptide encoded by mitochondrial DNA. It influences the mechanisms of obesity and diabetes. We hypothesised that the adiponectin pathway may regulate the production and/or secretion of MOTS-c in skeletal muscle. We aimed to determine whether exercise and adiponectin affect MOTS-c to improve insulin resistance in mice. To investigate this hypothesis, we used wild-type C57BL/6 mice subjected to high-fat diet, an exercise regimen, and i.p. injection of recombinant mouse adiponectin (Acrp30) or MOTS-c, and adiponectin knockout (Adipoq-/-) mice (C57BL/6 background) subjected to i.p. injection of Acrp30. C2C12 myotubes were also treated with sirtuin 1 (SIRT1) inhibitor, PGC-1α inhibitor, SIRT1 activator, plasmid-expressed active APPL1 (adaptor protein, phosphotyrosine interacting with PH domain and leucine zipper), pcDNA-SIRT1, or siRNA against APPL1, SIRT1 or PGC-1α. In Adipoq-/- mice, MOTS-c levels in the plasma and skeletal muscle were downregulated. In C2C12 myotubes, adiponectin increased the mRNA expression of MOTS-c. APPL1 protein level following adiponectin treatment positively correlated with MOTS-c protein and mRNA levels in C2C12 myotubes. SIRT1 overexpression increased the adiponectin-induced mRNA and protein expression of MOTS-c, SIRT1 and PGC-1α. Pharmacologic and genetic inhibition of PGC-1α suppressed the increases in MOTS-c mRNA and protein levels induced by SIRT1 overexpression. In mice, plasma and skeletal muscle MOTS-c levels were significantly downregulated following high-fat-diet. Exercise and i.p. Acrp30 or MOTS-c increased MOTS-c levels and adiponectin mRNA and protein expression in the plasma and skeletal muscle. Our findings showed that the APPL1-SIRT1-PGC-1α pathway regulates the production and/or secretion of skeletal muscle MOTS-c by mediating adiponectin signalling. Our study provides an insight into the cellular and molecular pathways underlying the pathogenesis of diabetes and shows that MOTS-c is a potential novel therapeutic target in the treatment of diabetes. Graphical abstract.