Effects Of Leptin Research Articles

Low-dose peripheral leptin infusion produces selective activation of ventromedial hypothalamic and hindbrain STAT3.

Previous studies have shown that very low dose, acute, single peripheral leptin injections fully activate arcuate nucleus signal transducer and activator of transcription 3 (STAT3), but ventromedial hypothalamus (VMH) pSTAT3 continues to increase with higher doses of leptin that inhibit food intake. The lowest dose that inhibited intake increased circulating leptin 300-fold whereas food intake is inhibited by chronic peripheral leptin infusions that only double circulating leptin. This study examined whether the pattern of hypothalamic pSTAT3 was the same in leptin-infused rats as in leptin-injected rats. Male Sprague-Dawley rats received intraperitoneal infusions of 0, 5, 10, 20, or 40 µg leptin/day for 9 days. The highest dose of leptin increased serum leptin by 50-100%, inhibited food intake for 5 days, but inhibited weight gain and retroperitoneal fat mass for 9 days. Energy expenditure, respiratory exchange ratio, and brown fat temperature did not change. pSTAT3 was quantified in hypothalamic nuclei and the nucleus of the solitary tract (NTS) when food intake was inhibited and when it had returned to control levels. There was no effect of leptin on pSTAT3 in the medial or lateral arcuate nucleus or in the dorsomedial nucleus of the hypothalamus. VMH pSTAT3 was increased only at day 4 when food intake was inhibited, but NTS pSTAT3 was increased at both 4 and 9 days of infusion. These results suggest that activation of leptin VMH receptors contributes to the suppression of food intake, but that hindbrain receptors contribute to a sustained change in metabolism that maintains a reduced weight and fat mass.NEW & NOTEWORTHY Low-dose, chronic peripheral infusions of leptin produced an initial, transient inhibition of food intake that correlated with signal transducer and activator of transcription 3 (STAT3) activation in the ventromedial hypothalamus (VMH) and nucleus of the solitary tract (NTS). When intake normalized, but weight remained suppressed, the NTS was the only area that remained activated. These data suggest that leptin's primary function is to reduce body fat, that hypophagia is a means of achieving this and that different areas of the brain are responsible for the progressive response.

Exploring the effects of adiponectin and leptin in correlating obesity with cognitive decline: a systematic review.

Obesity and cognitive decline including dementia and Alzheimer's Disease (AD) affect millions worldwide. Several studies have shown that obese individuals suffer from cognitive decline. Here, we suggest that adiponectin and leptin, protein hormones secreted by white adipose tissue explain the relationship between obesity and cognitive decline. We systematically searched PubMed and World Health Organization (WHO) websites with the keywords obesity and dementia and compiled literature that explains how adiponectin and leptin impact obesity and cognitive decline. Full-text, free-access articles on PubMed published after 2009 have been included. Whereas articles published before 2009, books, and reports were excluded. We concentrated on mechanisms via which adiponectin and leptin affect energy expenditure, fatty acid catabolism, satiety, hunger, Body Mass Index (BMI), neurogenesis, and brain structures that lead to the development of cognitive dysfunction. Moreover, we hypothesized that adiponectin and leptin hormones explain how obesity and dementia are connected. After compiling the research studies, we summarized that adiponectin and leptin negatively correlate to BMI. Adiponectin arbitrates energy expenditure and fatty acid catabolism to prevent obesity. In the presence of adiponectin, hippocampal cells proliferate, whereas neurogenesis is reduced in its absence. However, leptin prevents obesity by promoting satiety, reducing hunger, and increasing insulin sensitivity. It also has neuroprotective effects thus reducing the risk of developing cognitive decline. So, physical exercise, diet alteration, weight reduction, adiponectin, and leptin supplementation should be carried out to protect against obesity-induced cognitive decline. Therefore, further research studies should be done in this area.

Obesity and cancer: focus on leptin.

Over the past decades, obesity has grown to epidemic proportions worldwide. It hasbeen associated with an increasedriskfordifferent typesofcancer. In addition, obesity has been associated with a poor prognosis, an increased risk of metastasis and mortality, and resistance to anti-cancer therapies. The pathophysiological mechanisms underlying the obesity-cancer connection have not yet been fully elucidated. However, this connection could result, at least in part, from the action of adipokines, whose levels are increased in obesity. Among these adipokines, evidence suggests leptin's critical role in linking obesity to cancer. In this review, we first summarize the current state of the literature regarding the implication of leptin in tumorigenic processes. Next, we focus on the effects of leptin on the anti-tumor immune response. Then, we discuss the influence of leptin on the efficiency of antineoplastic treatments and the development of tumor resistance. Finally, we highlight the use of leptin as a potential target for the prevention and treatment of cancer.

Leptin-VEGF crosstalk in excess body mass and related disorders: A systematic review.

By 2030, it is expected that a billion people will have suffer from obesity. Adipose tissue synthesizes leptin, an adipokine that affects cardiovascular risk. Leptin intensifies the synthesis of vascular endothelial growth factor (VEGF). Our study reviews recent reports on leptin-VEGF crosstalk in obesity and related disorders. PubMed, Web of Science, Scopus, and Google Scholar were searched. One hundred and one articles involving human, animal, and in vitro research were included. In vitro studies show the crucial role of interaction between endothelial cells and adipocytes and hypoxia as a factor that intensifies leptin's effects on VEGF. Leptin-VEGF crosstalk promotes the progression of cancer. The animal research reveal that a high-fat diet enhances leptin and VEGF crosstalk. Genetic and epigenetic mechanisms and procreator-offspring programming may be involved in leptin-VEGF crosstalk. Some female-specific characteristics of leptin-VEGF relation in obesity were observed. The human studies have shown that increased leptin and VEGF synthesis and leptin-VEGF crosstalk are factors linking obesity with elevated cardiovascular risk. The studies of the last 10 years documented a range of significant aspects of leptin-VEGF crosstalk specific for obesity and related disorders, shedding new light on the link between obesity and increased cardiovascular risk.

(083) EMT Induced Transcription Factors Direct Leptin-LEPR-DHH Signaling to Modulate Leydig Stem Cells Differentiation in Testis

Abstract Introduction The primary source of testosterone (T) in men are Leydig cells (LCs) and their dysfunction can lead to T deficiency. Testicular microenvironment (TME) which is comparised of cells such as Sertoli and Peritubular myoid cells releases the paracrine factors to influence the growth and differentiation of LCs. Leptin is a 16-kDa protein produced primarily by adipose tissue and exerts a significant influence on hormonal regulation. In our recent study, we demonstrated that Leptin, a paracrine factor secreted by TME, is critical for Leydig stem cell (LSCs) differentiation and subsequent T production under the regulation of the desert hedgehog signalling pathway. We also showed that this regulation is inverse concentration dependent such as Leptin increases LSC differentiation at low doses and decrease it at higher doses. However, an in-depth understanding of mechanisms that derive the Leptin secretion and decide the fate of LCs are still unclear and is the focus of the present study. Objective To study the mechanisms that derive the Leptin secretion and decide the fate of LCs. Methods A total of 18 men with testicular failure underwent testis biopsies. The testicular cells were characterized using Flow cytometry, Immunostaining and RNA sequencing then the cells were also treated with Leptin in a dose dependent (0, 1, 10 ng/mL respectively) and time dependent (24, 48, 72, and 96 hours) manner. For the functional studies, UCSC genome browser was used to study the transcription factor genes (TFs) binding the leptin receptor (LEPR) promoter. The list of TFs was subjected to enrichment analysis. To evaluate the effects of shortlisted TFs on leptin-LEPR-DHH to induce EMT in LSCs, qPCR and western blotting were performed. For statistical analysis GraphPad Prism was used. For statistical analysis GraphPad Prism was used. All data were presented as the means ± SEM. All data were presented as the means ± SEM Results Over 60 TF’s were identified by UCSC Genome browser, which were subjected to enrichment analysis using ENRICHR and Ingenuity pathway analysis. Output revealed TFs; SOX2, SOX8 and SOX9 that were enriched for mechanisms influencing hormonal regulation via hypothalamic pituitary gonadal axis. The role of these TFs has been well established in epithelial to mesenchymal transition in different cancer types, however their impact on LSC differentiation remained underexplored. RNA sequencing data from cells exposed to different concentrations of Leptin showed an inducing effect of Leptin on SOX2, SOX8 Sox9 respectively. This was confirmed at RNA as well as at protein levels. Consequently, upon inhibition of LEPR, the expression of SOX2, SOX8 and SOX9 was reduced as well. Furthermore we used SOX8, SOX9 and SOX2 antagonists in the presence or absence of Leptin to validate the effects on EMT of LCs. Conclusions Our results demonstrate that Leptin-LEPR-DHH induced Leydig stem cells differentiation in testis is modulated by EMT inducing transcription factors which binds to LEPR. Further studies are ongoing to explore the potential therapeutic effects of leptin treatment in improving fertility. Disclosure No

Concentration-dependent effects of leptin on osteoarthritis-associated changes in phenotype of human chondrocytes

ABSTRACT Metabolic syndrome is a risk factor for osteoarthritis. Elevated leptin levels have been implicated as a potential cause of this association. Previous studies have shown that supra-physiological leptin concentrations can induce osteoarthritis-like changes in chondrocyte phenotype. Here, we tested the effects of leptin in the concentration range found in synovial fluid on chondrocyte phenotype. Chondrocytes isolated from macroscopically normal regions of cartilage within osteoarthritic joints from patients undergoing knee arthroplasty, all with body mass index >30 kg/m2 were treated with 2-40 ng/ml leptin for 24 h. Chondrocyte phenotype marker expression was measured by RT-qPCR and western blot. The role of HES1 in mediating the effects of leptin was determined by gene knockdown using RNAi and over-expression using adenoviral-mediated gene delivery. Treatment of chondrocytes with 20 or 40 ng/ml leptin resulted in decreased SOX9 levels and decreased levels of the SOX9-target genes COL2A1 and ACAN. Levels of HES1 were lower and ADAMTS5 higher in chondrocytes treated with 20 or 40 ng/ml leptin. HES1 knockdown resulted in increased ADAMTS5 expression whereas over-expression of HES1 prevented the leptin-induced increase in ADAMTS5. An increase in MMP13 expression was only evident in chondrocytes treated with 40 ng/ml leptin and was not mediated by HES1 activity. High concentrations of leptin can cause changes in chondrocyte phenotype consistent with those seen in osteoarthritis. Synovial fluid leptin concentrations of this level are typically observed in patients with metabolic syndrome and/or women, suggesting elevated leptin levels may form part of the multifactorial network that leads to osteoarthritis development in these patients.

Reversion of breast epithelial polarity alterations caused by obesity

Molecular links between breast cancer risk factors and pro-oncogenic tissue alterations are poorly understood. The goal of this study was to characterize the impact of overweight and obesity on tissue markers of risk, using normal breast biopsies, a mouse model of diet-induced obesity, and cultured breast acini. Proliferation and alteration of epithelial polarity, both necessary for tumor initiation, were quantified by immunostaining. High BMI (>30) and elevated leptin were associated with compromised epithelial polarity whereas overweight was associated with a modest increase in proliferation in human and mice mammary glands. Human serum with unfavorable adipokine levels altered epithelial polarization of cultured acini, recapitulating the effect of leptin. Weight loss in mice led to metabolic improvements and restored epithelial polarity. In acini cultures, alteration of epithelial polarity was prevented by antioxidants and could be reverted by normalizing culture conditions. This study shows that obesity and/or dietary factors modulate tissue markers of risk. It provides a framework to set target values for metabolic improvements and to assess the efficacy of interventional studies aimed at reducing breast cancer risk.

Effects of Leptin and Body Weight on Inflammation and Knee Osteoarthritis Phenotypes in Female Rats.

Leptin is a proinflammatory adipokine that contributes to obesity-associated osteoarthritis (OA), especially in women. However, the extent to which leptin causes knee OA separate from the effect of increased body weight is not clear. We hypothesized that leptin is necessary to induce knee OA in obese female rats but not sufficient to induce knee OA in lean rats lacking systemic metabolic inflammation. The effect of obesity without leptin signaling was modeled by comparing female lean Zucker rats to pair fed obese Zucker rats, which possess mutant fa alleles of the leptin receptor gene. The effect of leptin without obesity was modeled in female F344BN F1 hybrid rats by systemically administering recombinant rat leptin versus saline for 23 weeks via osmotic pumps. Primary OA outcomes included cartilage histopathology and subchondral bone micro-computed tomography. Secondary outcomes included targeted cartilage proteomics, serum inflammation, and synovial fluid inflammation following an acute intra-articular challenge with interleukin-1β (IL-1β). Compared to lean Zucker rats, obese Zucker rats developed more severe tibial osteophytes and focal cartilage lesions in the medial tibial plateau, with modest changes in proximal tibial epiphysis trabecular bone structure. In contrast, exogenous leptin treatment, which increased plasma leptin sixfold without altering body weight, caused mild generalized cartilage fibrillation and reduced Safranin O staining compared to vehicle-treated animals. Leptin also significantly increased subchondral and trabecular bone volume and bone mineral density in the proximal tibia. Cartilage metabolic and antioxidant enzyme protein levels were substantially elevated with leptin deficiency and minimally suppressed with leptin treatment. In contrast, leptin treatment induced greater changes in systemic and local inflammatory mediators compared to leptin receptor deficiency, including reduced serum IL-6 and increased synovial fluid IL-1β. In conclusion, rat models that separately elevate leptin or body weight develop distinct OA-associated phenotypes, revealing how obesity increases OA pathology through both leptin-dependent and independent pathways. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Leptin deficiency in CD8+ T cells ameliorates non-segmental vitiligo by reducing interferon-γ and Granzyme B.

Vitiligo is an autoimmune skin disease mainly mediated by CD8+ T cells, which affects about 0.1%-2% population of the world. Leptin plays a critical role in regulating the activation of CD8+ T cells. However, the effect of Leptin on vitiligo remains unclear. To explore the effect of leptin on CD8+ T cells and its influence on vitiligo. RNA sequencing and Quantitative Real-time PCR (RT-qPCR) were used to explore the differentially expressed genes. Immunofluorescence staining was performed on skin lesions. Leptin in serum was detected by enzyme linked immunosorbent assay (ELISA). The peripheral blood mononuclear cells were detected by flow cytometry after leptin stimulation for 72 hours. A vitiligo model was established by monobenzone on Leptin KO mice. 557 differentially expressed genes were found, including 154 up-regulated and 403 down-regulated genes. Lipid metabolism pathways showed a close relationship to the pathogenesis of vitiligo, especially the PPAR signaling pathway. RT-qPCR (p = 0.013) and immunofluorescence staining (p = 0.0053) verified that LEPR expressed significantly higher in vitiligo. The serum leptin level of vitiligo patients was significantly lower than that of healthy controls (p = 0.0245). The interferon-γ subset of CD8+LEPR+ T cells from vitiligo patients was significantly higher (p = 0.0189). The protein level of interferon-γ was significantly increased after leptin stimulation in vitro (p = 0.0217). In mice, Leptin deficiency resulted in less severe hair depigmentation. Leptin deficiency also resulted in significantly lower expressed vitiligo-related genes, such as Cxcl9 (p = 0.0497), Gzmb (p < 0.001), Ifng (p = 0.0159), and Mx1 (p < 0.001) after modeling. Leptin could promote the progression of vitiligo by enhancing the cytotoxic function of CD8+ T cells. Leptin may become a new target for vitiligo treatment.

Issue Information

Journal of NeurochemistryVolume 165, Issue 4 p. 455-456 ISSUE INFORMATIONFree Access Issue Information First published: 15 May 2023 https://doi.org/10.1111/jnc.15632 Read the full article: ‘A critical update on the leptin-melanocortin system’ by O. Lavoie, N. J. Michael and A. Caron (J. Neurochem. 2023, vol. 165 (4), pp. 467– 486) on doi:10.1111/jnc.15765 AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Graphical Abstract Front cover The race is ongoing to identify the still unknown GABAergic neurons that mediate the direct effects of leptin on energy homeostasis. However, does that one population really exist? Or is it the combination of many neurons, acting in a wide network to differentially control the various effects of leptin? Image content This RNA fluorescence in situ hybridization of the vesicular inhibitory amino acid transporter (VGAT, Slc32a1) shows the vast distribution of GABAergic neurons within the mouse nervous system. Read the full article ‘A critical update on the leptin-melanocortin system’ by O. Lavoie, N. J. Michael and A. Caron (J. Neurochem. 2023, vol. 165 (4), pp. 467– 486) on doi:10.1111/jnc.15765 Volume165, Issue4May 2023Pages 455-456 RelatedInformation

Setmelanotide, a melanocortin-4-receptor agonist, increases the hypercapnic ventilatory response and relieves hypoventilation in obese mice

Introduction: Obesity leads to high cardiorespiratory morbidity and mortality. Obese individuals can develop obesity hypoventilation syndrome (OHS) characterized by daytime hypercapnia in the absence of alternative underlying causes. OHS leads to daytime sleepiness, cardiovascular complications, and cyanosis. There is no effective pharmacotherapy for OHS. Leptin, an adipose-produced hormone, improves breathing in OHS, but obese individuals and rodents are resistant to the beneficial effects of leptin. The melanocortin axis is a downstream target of leptin but effects of this axis on control of breathing are poorly studied. Setmelanotide is an FDA-approved drug for weight loss that specifically binds to the melanocortin 4 receptor (MC4R). We have previously demonstrated that C57BL/6J mice with diet induced obesity (DIO) hypoventilate during sleep and exhibit all features of OHS. We hypothesized that the activation of MC4R by setmelanotide augments the control of breathing during sleep in DIO mice. Methods: We performed a proof-of-concept single dose randomized trial of intraperitoneal setmelanotide (1.0 mg/kg) vs vehicle in DIO C57BL/6J mice using a cross-over design. The injections were followed by sleep studies, and measurements of the hypercapnic ventilatory response, oxygen consumption (VO2), and carbon dioxide production (VCO2). Results: Activation of MC4R by setmelanotide increased inspiratory flow, respiratory rate, and minute ventilation during NREM and REM sleep compared to vehicle. Activation of MC4R by setmelanotide increased the hypercapnic ventilatory response. Setmelanotide also increased VCO2, and VO2, but the ventilation was increased out of proportion to the upregulation of metabolism, which was evident from increases in the VE/VO2 and VE/VCO2 ratios. Conclusion: Activation of MC4R by setmelanotide relieved hypoventilation during sleep and increased the hypercapnic ventilatory response in obese mice. Our study identified MC4 as a promising therapeutic target in OHS. NIH (R01 HL128970, R01 HL133100, and R01 HL138932), AHA (#915167). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Intranasal Leptin Prevents Opioid-Induced Respiratory Depression in Obese, Opioid Tolerant Mice

Opioid-induced respiratory depression (OIRD) is the primary cause of death associated with opioids and individuals with obesity are particularly susceptible due to comorbid obstructive sleep apnea (OSA). Repeated exposure to opioids, as in the case of pain management, results in diminished therapeutic effect and/or the need for higher doses to maintain the same effect. With limited means to address the negative impact of repeated exposure it is critical to develop drugs that prevent deaths induced by opioids without reducing beneficial analgesia or causing withdrawal symptoms. We have previously shown that intranasal (IN) leptin can reverse apneas, hypoventilation, and upper airway obstruction while enhancing analgesia following acute morphine administration. Here we hypothesize that OIRD as a result of chronic opioid use can be attenuated by administration of IN leptin without acute withdrawal while also maintaining analgesia in both lean mice and mice with diet-induced obesity (DIO). To test this hypothesis, an opioid tolerance protocol was developed and a model of OIRD in mice chronically receiving morphine and tolerant to morphine analgesia was established. Subsequently, sleep and breathing were recorded by barometric plethysmography following acute or chronic administration of IN leptin. Operant behavioral assays and Pavlovian conditioning procedures were used to determine the impact of IN leptin on the analgesic efficacy of morphine and opioid withdrawal symptoms. Acute administration of IN leptin significantly attenuated OIRD in DIO male mice decreasing the apnea index by 58.9% and apnea time by 60.1%. In lean mice leptin was ineffective. Chronic IN leptin induced &gt; 50% reduction in the OIRD in morphine tolerant DIO male mice suggesting the protective effect of leptin remained after the two-week treatment. Morphine caused a complete loss of temperature aversion which was not reduced by intranasal leptin indicating IN leptin does not decrease morphine analgesia. IN leptin did not modify naloxone conditional place aversion or naloxone withdrawal symptoms, suggesting that IN treatment does not induce opioid withdrawal. We conclude that IN leptin is ineffective in lean mice but prevents OIRD in obesity by increasing hypercapnic sensitivity when leptin resistance at the BBB is present without reducing analgesia or inducing withdrawal. NIH R61HL156240; NIH R01HL128970; NIH R41DA056239 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Maturational effect of leptin on CO2 chemosensitivity in newborn rats.

Leptin augments central CO2 chemosensitivity and stabilizes breathing in adults. Premature infants have unstable breathing and low leptin levels. Leptin receptors are on CO2 sensitive neurons in the Nucleus Tractus Solitarius (NTS) and locus coeruleus (LC). We hypothesized that exogenous leptin improves hypercapnic respiratory response in newborn rats by improving central CO2 chemosensitivity. In rats at postnatal day (p)4 and p21, hyperoxic and hypercapnic ventilatory responses, and pSTAT and SOCS3 protein expression in the hypothalamus, NTS and LC were measured before and after treatment with exogenous leptin (6 µg/g). Exogenous leptin increased the hypercapnic response in p21 but not in p4 rats (P ≤ 0.001). At p4, leptin increased pSTAT expression only in the LC, and SOCS3 expression in the NTS and LC; while at p21 pSTAT and SOCS3 levels were higher in the hypothalamus, NTS, and LC (P ≤ 0.05). We describe the developmental profile of the effect of exogenous leptin on CO2 chemosensitivity. Exogenous leptin does not augment central CO2 sensitivity during the first week of life in newborn rats. The translational implication of these findings is that low plasma leptin levels in premature infants may not be contributing to respiratory instability. Exogenous leptin does not augment CO2 sensitivity during the first week of life in newborn rats, similar to the developmental period when feeding behavior is resistant to leptin. Exogenous leptin increases CO2 chemosensitivity in newborn rats after the 3rd week of life and upregulates the expression of pSTAT and SOC3 in the hypothalamus, NTS and LC. Low plasma leptin levels in premature infants are unlikely contributors to respiratory instability via decreased CO2 sensitivity in premature infants. Thus, it is highly unlikely that exogenous leptin would alter this response.

Obesity Is Associated with Immunometabolic Changes in Adipose Tissue That May Drive Treatment Resistance in Breast Cancer: Immune-Metabolic Reprogramming and Novel Therapeutic Strategies.

White adipose tissue (WAT) represents an endocrinologically and immunologically active tissue whose primary role is energy storage and homeostasis. Breast WAT is involved in the secretion of hormones and proinflammatory molecules that are associated with breast cancer development and progression. The role of adiposity and systemic inflammation in immune responses and resistance to anti-cancer treatment in breast cancer (BC) patients is still not clear. Metformin has demonstrated antitumorigenic properties both in pre-clinical and clinical studies. Nevertheless, its immunomodulating properties in BC are largely unknown. This review aims to evaluate the emerging evidence on the crosstalk between adiposity and the immune-tumour microenvironment in BC, its progression and treatment resistance, and the immunometabolic role of metformin in BC. Adiposity, and by extension subclinical inflammation, are associated with metabolic dysfunction and changes in the immune-tumour microenvironment in BC. In oestrogen receptor positive (ER+) breast tumours, it is proposed that these changes are mediated via a paracrine interaction between macrophages and preadipocytes, leading to elevated aromatase expression and secretion of pro-inflammatory cytokines and adipokines in the breast tissue in patients who are obese or overweight. In HER2+ breast tumours, WAT inflammation has been shown to be associated with resistance to trastuzumab mediated via MAPK or PI3K pathways. Furthermore, adipose tissue in patients with obesity is associated with upregulation of immune checkpoints on T-cells that is partially mediated via immunomodulatory effects of leptin and has been paradoxically associated with improved responses to immunotherapy in several cancers. Metformin may play a role in the metabolic reprogramming of tumour-infiltrating immune cells that are dysregulated by systemic inflammation. In conclusion, evidence suggests that body composition and metabolic status are associated with patient outcomes. To optimise patient stratification and personalisation of treatment, prospective studies are required to evaluate the role of body composition and metabolic parameters in metabolic immune reprogramming with and without immunotherapy in patients with BC.

Effects of leptin on the viability of human ovarian cancer cells and changes in cytokine expression levels.

Obesity is associated with increased mortality among ovarian cancer and is a poor prognostic factor. There are significant links between the leptin hormone, a product of the obesity gene, and the development of ovarian cancer. Leptin is a vital hormone-like cytokine secreted from adipose tissue and is mainly involved in the maintenance of energy homeostasis. It regulates several intracellular signaling pathways and also interacts with various hormones and energy regulators. It acts as a growth factor by stimulating cell proliferation and differentiation and in this way contributes to cancer cell development. The aim of the study was to investigate the effects of leptin on human ovarian cancer cells. In this study, the effects of increasing the concentration of leptin were investigated on the cell viability of OVCAR-3 and MDAH-2774 ovarian cancer lines by MTT assay. Moreover, to elucidate the molecular mechanisms of leptin in ovarian cancer cells, changes in the expression levels of 80 cytokines were evaluated after leptin treatment via a human cytokine antibody array. Leptin increases the proliferation of both ovarian cancer cell lines. IL-1 level was increased in OVCAR-3 cells and TGF-β level was increased in MDAH-2774 cells after leptin treatment. A decrease in IL-2, MCP-2/CCL8 and MCP-3/CCL7 levels was detected in both ovarian cancer cell lines with leptin administration. An increase in IL-3 and IL-10 expressions, insulin-like growth factor binding proteins (IGFBP) IGFBP-1, IGFBP-2 and IGFBP-3 levels were detected in both ovarian cancer cell lines with leptin administration. In conclusion; leptin has a proliferative effect on human ovarian cancer cell lines and affects different cytokines in different types of ovarian cancer cells.

Identification of a GABAergic neural circuit governing leptin signaling deficiency-induced obesity.

The hormone leptin is known to robustly suppress food intake by acting upon the leptin receptor (LepR) signaling system residing within the agouti-related protein (AgRP) neurons of the hypothalamus. However, clinical studies indicate that leptin is undesirable as a therapeutic regiment for obesity, which is at least partly attributed to the poorly understood complex secondary structure and key signaling mechanism of the leptin-responsive neural circuit. Here, we show that the LepR-expressing portal neurons send GABAergic projections to a cohort of α3-GABAA receptor expressing neurons within the dorsomedial hypothalamic nucleus (DMH) for the control of leptin-mediated obesity phenotype. We identified the DMH as a key brain region that contributes to the regulation of leptin-mediated feeding. Acute activation of the GABAergic AgRP-DMH circuit promoted food intake and glucose intolerance, while activation of post-synaptic MC4R neurons in the DMH elicited exactly opposite phenotypes. Rapid deletion of LepR from AgRP neurons caused an obesity phenotype which can be rescued by blockage of GABAA receptor in the DMH. Consistent with behavioral results, these DMH neurons displayed suppressed neural activities in response to hunger or hyperglycemia. Furthermore, we identified that α3-GABAA receptor signaling within the DMH exerts potent bi-directional regulation of the central effects of leptin on feeding and body weight. Together, our results demonstrate a novel GABAergic neural circuit governing leptin-mediated feeding and energy balance via a unique α3-GABAA signaling within the secondary leptin-responsive neural circuit, constituting a new avenue for therapeutic interventions in the treatment of obesity and associated comorbidities.

Leptinin Yara İyileşmesi Üzerine In Vitro Etkisinin Büyüme Faktörleri Üzerinden İncelenmesi

Yara iyileşmesi; epitelyal, endotelyal, mezenkimal ve inflamatuvar hücrelerin biraraya gelip, normal işlevlerini belirli bir sıra ve düzen içerisinde yerine getirmeleriyle karakterizedir. Leptin, ağırlıklı olarak yağ dokusundan salgılanan ve yara iyileşme süresini kısalttığı bilinen sitokin benzeri bir hormondur. Bu çalışmada; fibroblast hücrelerinde yara iyileşmesi modeli oluşturarak leptinin doz (100 ng/mL, 200 ng/mL, 400 ng/mL ve 800 ng/mL) ve süre (24 ve 48 saat) bağımlı etkilerinin in vitro yöntemlerle incelenmesi amaçlanmıştır. Yara modeli oluşturulan hücreler üzerine artan dozlarda leptin uygulaması yapıldıktan 24 ve 48 saat sonra yara alanlarının kapanma oranları hesaplandı. Hücre canlılığını belirlemek amacı ile WST-1 analizi yapıldı. Crystal Violet boyaması ile fibroblast hücreleri morfolojik olarak incelendi ve FGFR2, KGF (FGF7), TGF-α, TGF-β1 ve Ki67 ekspresyonlarını belirlemek için de immunositokimya (ICC) analizi yapılarak H-Skor değerleri hesaplandı. In vitro yara modeli analizinde fibroblast hücrelerinin en yüksek yüzde kapanma oranı ve WST-1 analizi ile en yüksek hücre canlılık yüzdesi 48 saat 800 ng/mL leptin uygulanan grupta tespit edildi. ICC sonucunda elde edilen H-Skor değerleri ise, değerlendirilen proteinlerin ekspresyonlarının fibroblast hücrelerinde leptin dozu ve süresine bağlı olarak arttığını gösterdi. Çalışma sonucunda fibroblast hücrelerinde leptinin in vitro yara iyileşmesini sağlayan en etkili dozunun 800 ng/mL olduğu belirlenmiştir. Ayrıca FGFR2, KGF (FGF7), TGF-α, TGF-β1 ve Ki67 ekspresyonlarının leptin dozuna ve uygulama süresine bağlı olarak hücrelerde arttığı ve en yüksek artışın en yüksek dozda ortaya çıktığı gösterilmiştir. Bu çalışmanın sonuçlarının, yapılacak olan in vivo yara iyileşmesi araştırmalarında leptin kullanımına öncülük edeceği düşünülmektedir.

Deficient leptin receptor signaling in T cells of human SLE.

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease mainly mediated by IgG autoantibody. While follicular helper T (Tfh) cells are crucial for supporting IgG autoantibody generation in human SLE, underlying mechanisms for Tfh cell mal-differentiation remain unclear. In total, 129 SLE patients and 37 healthy donors were recruited for this study. Circulating leptin was determined by ELISA from patients with SLE and healthy individuals. CD4 T cells isolated from SLE patients and healthy donors were activated with anti-CD3/CD28 beads under cytokine-unbiased conditions in the presence or absence of recombinant leptin protein, followed by detection for Tfh cell differentiation by quantifying intracellular transcription factor Bcl-6 and cytokine IL-21. AMPK activation was assessed by analyzing phosphor-AMPK using phosflow cytometry and immunoblots. Leptin receptor expression was determined using flow cytometry and its overexpression was achieved by transfection with an expression vector. Humanized SLE chimeras were induced by injecting patients' immune cells into immune-deficient NSG mice and used for translational studies. Circulating leptin was elevated in patients with SLE, inversely associated with disease activity. In healthy individuals, leptin efficiently inhibited Tfh cell differentiation through inducing AMPK activation. Meanwhile, leptin receptor deficiency was a feature of CD4 T cells in SLE patients, impairing the inhibitory effect of leptin on the differentiation of Tfh cells. As a result, we observed the coexistence of high circulating leptin and increased Tfh cell frequencies in SLE patients. Accordingly, overexpression of leptin receptor in SLE CD4 T cells abrogated Tfh cell mal-differentiation and IgG anti-dsDNA generation in humanized lupus chimeras. Leptin receptor deficiency blocks the inhibitory effect of leptin on SLE Tfh cell differentiation, serving as a promising therapeutic target for lupus management.

Smooth Muscle Cells from a Rat Model of Obesity and Hyperleptinemia Are Partially Resistant to Leptin-Induced Reactive Oxygen Species Generation

The aim of this study was to evaluate the effect of leptin on reactive oxygen species' (ROS) generation of smooth muscle cells (SMCs) from a rat model of obesity and hyperleptinemia. Obesity and hyperleptinemia were induced in rats by a sucrose-based diet for 24 weeks. ROS generation was detected by using dichloro-dihydrofluorescein (DCF), a fluorescent ROS probe in primary SMCs culture. An increase in plasma leptin and oxidative stress markers was observed in sucrose-fed (SF) rats. At baseline SMCs from SF rats showed a more than twofold increase in fluorescence intensity (FI) compared to that obtained in control (C) cells. When the C cells were treated with 20 ng leptin, the FI increased by about 250%, whereas the leptin-induced FI in the SF cells increased only by 28%. In addition, sucrose feeding increased the levels of p22phox and gp91phox, subunits of Nox as an O2•- source in SMCs. Treatment of cells with leptin significantly increased p22phox and gp91phox levels in C cells and did not affect SF cells. Regarding STAT3 phosphorylation and the content of PTP1B and SOCS3 as protein markers of leptin resistance, they were found to be significantly increased in SF cells. These results suggest that SF aortic SMCs are partially resistant to leptin-induced ROS generation.

Role of the adipocyte immune brain axis in Parkinson's disease: friend or foe?

Role of the adipocyte immune brain axis in Parkinson's disease: friend or foe?