Leptin Receptor Expression Research Articles

Expression of leptin and leptin receptor transcript in ovine corpus luteum

Background: Leptin, the product of the obesity (ob) gene, acts as a signaling adipokine for modulating food intake, energy metabolism and reproductive functions in mammals. Leptin’s effects on the reproductive system at various levels of the hypothalamic-pituitary-gonadal axis have been established. Moreover, the direct and local effect of leptin on bovine oocyte maturation and corpus luteum function has been determined. Objectives: Due to species differences, this study was designed to investigate expression of leptin mRNA as well as its long isoform receptor (Ob-Rb) mRNA in sheep corpus luteum. Methods: Ovaries of sheep containing mature corpus luteum were collected in the reproductive season from abattoirs. Total RNA of corpus luteum was extracted, cDNA synthesis was carried out subsequently and PCR reaction was performed using primers which were designed specifically for each gene. Beta-actin was used as housekeeping gene to verify reactions, and adipose tissue was selected as positive sample for expression of leptin and leptin receptor. Results: Gel electrophoresis of PCR products showed the amplification of 162 and 121-bp amplicons in all samples for leptin and leptin receptor respectively. Moreover, sequencing the amplified fragments and blasting them confirmed the accuracy of results. Conclusion: Our findings confirm the expression of leptin and its functional receptor transcripts in ovine corpus luteum. More studies for determining leptin effects on corpus luteum are guaranteed.

Gene expression profiling in embryonic chicken ovary during asymmetric development.

The reproductive system in female birds arises as bilateral asymmetrical anlagen, excluding the birds of prey. Earlier, histological and messenger RNA (mRNA) expression profile studies of several genes related to gonadal sex differentiation in chicken embryos tried to elucidate the query of this asymmetry in a scattered manner. To understand the matter precisely, we have focused on mRNA expression of a cohort of genes (FSHR, CYP19A1, caspase 3, caspase 8) in second half of the embryonic days (E10-E18). The established role of leptin in development of the embryo and its expression in the embryonic ovary also drove us to check leptin receptor (LEPR) expression in the ovary. Increased expression of FSHR and CYP19A1 in the left ovary compared with that in the right ovary was identified (P<0.05), promoting preferential left ovarian development and functionality. Significant high expression (P<0.05) of the apoptotic genes in the right ovary were also involved here. Leptin probably has no direct influence on ovarian asymmetry as no significant variation in gonadal mRNA expression of LEPR was observed within the same experimental days. We propose that asymmetric expression of this cohort of genes (FSHR, CYP19A1, caspase 3, caspase 8) leads to the development of dimorphic gonads during embryogenesis.

Associations between serum leptin levels, hyperlipidemia, and cholelithiasis in dogs.

Leptin and its receptor play several physiological roles in the canine gallbladder, and the dysregulation of leptin might play a role in the pathogenesis of gallbladder diseases such as gallbladder mucocele. Previous studies revealed a positive association between hyperlipidemia and gallstones in humans. However, the latter is still unclear in dogs with cholelithiasis. In this study, we examined the differences in leptin, leptin receptor, total cholesterol, and triglyceride levels between healthy dogs and dogs with cholelithiasis, and evaluated the correlation between leptin and hyperlipidemia. Twenty-eight healthy dogs and 34 client-owned dogs with cholelithiasis were enrolled in the study. Leptin concentrations and lipid profiles were determined from sera, and leptin and leptin receptor expression levels were quantified in gallbladder tissue. In dogs with cholelithiasis, serum concentrations of leptin (p < 0.001), total cholesterol (p < 0.001), and triglycerides (p < 0.001) were significantly higher compared with those in healthy dogs. Positive correlations were observed between serum leptin and total cholesterol (95% confidence interval (CI) = 0.61–0.89, r = 0.725, p < 0.001), and between leptin and triglycerides (95% CI = 0.63–0.89, r = 0.782, p < 0.001) in the cholelithiasis group. Hypercholesterolemia (Odds Ratio (OR) = 9.720; 95% CI = 1.148–82.318) and hypertriglyceridemia (OR = 12.913; 95% CI = 1.548–107.722) were shown to be risk factors for gallstone disease. In cholelithiasis patients who underwent cholecystectomy, serum leptin levels were significantly higher than in patients that had not undergone surgery (p < 0.001). Leptin and leptin receptor expression was upregulated in the gallbladder tissues of cholelithiasis patients (p < 0.01 and p < 0.001, respectively). These results indicate that increased serum leptin concentrations and hyperlipidemia (hypercholesterolemia or hypertriglyceridemia) are associated with canine cholelithiasis and that homeostatic imbalance of these parameters might affect the pathogenesis of gallstones.

Differential adipokine receptor expression on circulating leukocyte subsets in lean and obese children

BackgroundChildhood obesity prevalence has increased worldwide and is an important risk factor for type 2 diabetes (T2D) and cardiovascular disease (CVD). The production of inflammatory adipokines by obese adipose tissue contributes to the development of T2D and CVD. While levels of circulating adipokines such as adiponectin and leptin have been established in obese children and adults, the expression of adiponectin and leptin receptors on circulating immune cells can modulate adipokine signalling, but has not been studied so far. Here, we aim to establish the expression of adiponectin and leptin receptors on circulating immune cells in obese children pre and post-lifestyle intervention compared to normal weight control children.Methods13 obese children before and after a 1-year lifestyle intervention were compared with an age and sex-matched normal weight control group of 15 children. Next to routine clinical and biochemical parameters, circulating adipokines were measured, and flow cytometric analysis of adiponectin receptor 1 and 2 (AdipoR1, AdipoR2) and leptin receptor expression on peripheral blood mononuclear cell subsets was performed.ResultsObese children exhibited typical clinical and biochemical characteristics compared to controls, including a higher BMI-SD, blood pressure and circulating leptin levels, combined with a lower insulin sensitivity index (QUICKI). The 1-year lifestyle intervention resulted in stabilization of their BMI-SD. Overall, circulating leukocyte subsets showed distinct adipokine receptor expression profiles. While monocytes expressed high levels of all adipokine receptors, NK and iNKT cells predominantly expressed AdipoR2, and B-lymphocytes and CD4+ and CD8+ T-lymphocyte subsets expressed AdipoR2 as well as leptin receptor. Strikingly though, leukocyte subset numbers and adipokine receptor expression profiles were largely similar in obese children and controls. Obese children showed higher naïve B-cell numbers, and pre-intervention also higher numbers of immature transition B-cells and intermediate CD14++CD16+ monocytes combined with lower total monocyte numbers, compared to controls. Furthermore, adiponectin receptor 1 expression on nonclassical CD14+CD16++ monocytes was consistently upregulated in obese children pre-intervention, compared to controls. However, none of the differences in leukocyte subset numbers and adipokine receptor expression profiles between obese children and controls remained significant after multiple testing correction.ConclusionsFirst, the distinct adipokine receptor profiles of circulating leukocyte subsets may partly explain the differential impact of adipokines on leukocyte subsets. Second, the similarities in adipokine receptor expression profiles between obese children and normal weight controls suggest that adipokine signaling in childhood obesity is primarily modulated by circulating adipokine levels, instead of adipokine receptor expression.

Age-Dependent Neurochemical Remodeling of Hypothalamic Astrocytes.

The hypothalamus is a crucial integrative center in the central nervous system, responsible for the regulation of homeostatic activities, including systemic energy balance. Increasing evidence has highlighted a critical role of astrocytes in orchestrating hypothalamic functions; they participate in the modulation of synaptic transmission, metabolic and trophic support to neurons, immune defense, and nutrient sensing. In this context, disturbance of systemic energy homeostasis, which is a common feature of obesity and the aging process, involves inflammatory responses. This may be related to dysfunction of hypothalamic astrocytes. In this regard, the aim of this study was to evaluate the neurochemical properties of hypothalamic astrocyte cultures from newborn, adult, and aged Wistar rats. Age-dependent changes in the regulation of glutamatergic homeostasis, glutathione biosynthesis, amino acid profile, glucose metabolism, trophic support, and inflammatory response were observed. Additionally, signaling pathways including nuclear factor erythroid-derived 2-like 2/heme oxygenase-1 p38 mitogen-activated protein kinase, nuclear factor kappa B, phosphatidylinositide 3-kinase/Akt, and leptin receptor expression may represent putative mechanisms associated with the cellular alterations. In summary, our findings indicate that as age increases, hypothalamic astrocytes remodel and exhibit changes in their neurochemical properties. This process may play a role in the onset and/or progression of metabolic disorders.

Regulation of PD-1 and leptin receptor expression by estrogen through AKT3 in human uterine fibroids

Regulation of PD-1 and leptin receptor expression by estrogen through AKT3 in human uterine fibroids

OP.8B.05] TRANSGENERATIONAL INHERITANCE OF OBESITY AND HYPERTENSION

Objective: Maternal obesity increases the risk of developing hypertension in the offspring. Circulating leptin is closely linked to the control of sympathetic nerve activity (SNA) and blood pressure (BP) in the central nerve system. The ventromedial hypothalamus (VMH) is a key center of energy homeostasis, hemodynamic and sympathetic tone to renal vasculature. Exposure to overnutrition during early development changes the activity of the neurons and the receptors in the CNS, amplifying sympathetic output which leads to hypertension. We assessed the effects of maternal high fat diet (HFD) feeding during pregnancy on cardiovascular variables and sympathetic nerve activity (SNA) with changes in leptin and insulin signaling pathways in adulthood. Design and method: Breeder rabbits were fed a HFD (13%; HFD) or a control diet (4%; CD) during pregnancy and lactation. Offspring received CD after weaning. All rabbits had a VMH cannula and a renal nerve recording electrode. Mean arterial pressure (MAP), heart rate (HR) and renal sympathetic nerve activity (RSNA) were measured at baseline and after receiving increasing doses of αMSH (α-Melanocortin stimulating hormone, 0.3, 1nmol), SHU9119 (melanocortin receptor antagonist, 0.02, 0.04nmol), leptin receptor antagonist (5, 10 μg) or insulin receptor antagonist (0.01, 0.05U). Hypothalamic expression of leptin receptor (LepR) and Phosphoinositide 3-kinase (PI3K) was examined using real-time PCR. Results: Offspring from HFD fed rabbits (mHFD) showed higher MAP (+11%) and RSNA (+42%) than controls in adulthood (P < 0.05). αMSH into the VMH increased MAP, HR and RSNA (+6.6 ± 1mmHg, +23.4 ± 3.45 b/min and +3.66 ± 0.7nu) and SHU9119 reduced MAP and RSNA (−5.6 ± 0.8mmHg, −1.3 ± 0.13 nu) in mHFD rabbits. Leptin receptor antagonist normalized hypertension (−5.8 ± 0.8mmHg) in mHFD rabbits (P < 0.05). Insulin receptor antagonist administration into the VMH showed no changes in MAP, HR and RSNA in both mHFD and mCD rabbits. Offspring from maternal HFD rabbits exhibited an increase in LepR and PI3K expression in the hypothalamus compared to the control group (+47% and +74%). Conclusions: Exposure to over-nutrition during early development leads to permanently altered leptin and MC signaling pathways, due to programming of the key receptors and/or by neuronal plasticity, leading to sympathoexcitation and hypertension in adulthood.

Effects of androgens on the leptin system in immature male Atlantic salmon parr

Leptin modulates all levels of the reproductive endocrine axis in mammals, and in turn, both leptin and the leptin receptor are regulated by sex steroids. The aim of this study was to investigate if sex steroids regulate the leptin system also in fish. Immature one-year old male Atlantic salmon parr were implanted with Silclear capsules that were either empty or filled with 11-ketoandrostenedione (11KA) or testosterone (T) and the effects of 35-days treatment were investigated on measures of maturation, gene expression of leptin (lepa1, lepa2), leptin receptor (lepra1) and circulating plasma leptin. Both 11-KA and T stimulated the reproductive axis by increasing testes weight and up-regulated pituitary lh-β mRNA levels and for T also fsh-β. T up-regulated transcription levels of lepa1 and lepra1 in the pituitary, while 11-KA had no effect. Leptin receptor expression in the testis was unaltered by either androgen. T up-regulated lepa1 mRNA levels significantly also in the liver, but had no effect on lepa2, and 11KA did not affect hepatic gene expression of either lepa1 or lepa2. Plasma leptin levels did not differ significantly between treatments. The results indicate that androgens regulate gene expression of leptin and the leptin receptor in different tissues in fish and that the effects of leptin might be tissue specific considering plasma levels remained unaltered. Overall, the results suggest a role for leptin in fish reproduction, where sex steroids are able to regulate components of the leptin system differentially in liver and important tissues of the reproductive axis.

The role of leptin in the central nervous system remyelination

Leptin is identified as a mouse obesity gene, which is also preserved in humans. Leptin receptor is highly expressed in the hypothalamus relative to other tissues; therefore, the function of leptin is mainly attributed to hypothalamic control of food intake and body weight. Although the expression of leptin receptors is not limited to the hypothalamus but is also present in other regions of the central nervous system (CNS), such as the spinal cord, the functions of leptin and leptin receptor in the CNS have not been fully clarified. In this research highlight, we focus on the novel function of leptin in CNS remyelination in pathologic conditions, such as the demyelination mouse model. Because remyelination is a crucial process for repair of neuronal networks after injury and wound healing, knowledge of the underlying molecular mechanism of remyelination is useful to establish a therapeutic strategy against demyelinating diseases. We only revealed the role of leptin in remyelination at a histological level; however, a behavioral analysis and evidence of the beneficial effect of leptin for humans may add to knowledge of the effect of leptin on remyelination function.

Correction: Maternal High-Fat Diet During Pregnancy and Lactation has Opposite Effects on Gonadal Expression of Leptin and Leptin Receptor in Rat Dams and Their Offspring.

This study investigated the effect of a high-fat (HF) diet on protein expression of leptin and its receptor in the gonads of dams and their offspring. Female Wistar rats were fed a HF diet (30% fat) or a standard breeding (BD) diet (5% fat) during pregnancy and lactation. At 21 days of lactation, mothers and both sexes of prepubertal offspring were killed by decapitation. The protein expression of leptin and its receptor was assayed by Western blot and immunohistochemistry in gonadal, periovarian, and epididymal white adipose tissue (WAT). We demonstrated that leptin protein expression in ovary, and both leptin and ObRb expression in periovarian WAT was decreased in HF dams compared with BD animals. Immunohistochemistry showed lower leptin expression in growing antral follicles and corpora lutea of HF dams. Conversely, in both gonads and epididymal WAT of HF offspring, leptin and its receptor were significantly higher expressed compared with BD. Immunolocalization of leptin system in HF offspring gonads showed higher expression in growing and antral follicles of the ovary, seminiferous tubules, and interstitial tissue of testes. In conclusion, high gonadal and gonadal-WAT expression of leptin system was observed in the offspring of dams fed a HF diet during pregnancy and lactation.

Maternal High-Fat Diet During Pregnancy and Lactation has Opposite Effects on Gonadal Expression of Leptin and Leptin Receptor in Rat Dams and Their Offspring.

This study investigated the effect of a high-fat (HF) diet on protein expression of leptin and its receptor in the gonads of dams and their offspring. Female Wistar rats were fed a HF diet (30% fat) or a standard breeding (BD) diet (5% fat) during pregnancy and lactation. At 21 days of lactation, mothers and both sexes of prepubertal offspring were killed by decapitation. The protein expression of leptin and its receptor was assayed by Western blot and immunohistochemistry in gonadal, periovarian, and epididymal white adipose tissue (WAT). We demonstrated that leptin protein expression in ovary, and both leptin and ObRb expression in periovarian WAT was decreased in HF dams compared with BD animals. Immunohistochemistry showed lower leptin expression in growing antral follicles and corpora lutea of HF dams. Conversely, in both gonads and epididymal WAT of HF offspring, leptin and its receptor were significantly higher expressed compared with BD. Immunolocalization of leptin system in HF offspring gonads showed higher expression in growing and antral follicles of the ovary, seminiferous tubules, and interstitial tissue of testes. In conclusion, high gonadal and gonadal-WAT expression of leptin system was observed in the offspring of dams fed a HF diet during pregnancy and lactation.

Roux-en-Y gastric bypass surgery suppresses hypothalamic PTP1B protein level and alleviates leptin resistance in obese rats.

The present study aimed to explore the effect of Roux-en-Y gastric bypass (RYGB) surgery on protein tyrosine phosphatase 1B (PTP1B) expression levels and leptin activity in hypothalami of obese rats. Obese rats induced by a high-fat diet (HFD) that underwent RYGB (n=11) or sham operation (SO, n=9), as well as an obese control cohort (Obese, n=10) and an additional normal-diet group (ND, n=10) were used. Food efficiency was measured at 8 weeks post-operation. Plasma leptin levels were evaluated and hypothalamic protein tyrosine phosphatase 1B (PTP1B) levels and leptin signaling activity were examined at the genetic and protein levels. The results indicated that food efficiency was typically lower in RYGB rats compared with that in the Obese and SO rats. In the RYGB group, leptin receptor expression and proopiomelanocortin was significantly higher, while Neuropeptide Y levels were lower than those in the Obese and SO groups. Furthermore, the gene and protein expression levels of PTP1B in the RYGB group were lower, while levels of phosphorylated signal transducer and activator of transcription 3 protein were much higher compared with those in the Obese and SO groups. In conclusion, RYGB surgery significantly suppressed hypothalamic PTP1B protein expression. PTP1B regulation may partially alleviate leptin resistance.

Abstract 3544: Leptin-Notch crosstalk axis: A novel target for pancreatic cancer

Abstract Background: Pancreatic cancer (PC) has consistently been the fourth cancer-related cause of death in United States for more than 10 years. Its dismal prognosis is due to the aggressive behavior, late detection, lack of reliable biomarkers and low response to chemotherapy. Obesity, characterized by high levels of leptin, correlates to low PC survival. Notch and leptin signaling have been associated with increased tumor growth and chemoresistance. We have previously shown that leptin induces proliferation of PC cell lines, increases Notch expression, PC stem cells (PCSC) and tumorsphere formation. Hypothesis: Leptin increases PC chemoresistance through its crosstalk to Notch signaling pathway that is essential for the expansion of PCSC. Methods: To test whether a leptin-Notch crosstalk axis is involved in PC-chemoresistance, human PC (MiaPaCa-2, Panc-1 and BxPC-3) cells were cultured in serum-free medium containing leptin, Gemcitabine and 5-Fluorouracil (5-FU) in combination with DAPT (γ-secretase inhibitor) and leptin signaling inhibitor bound to iron-oxide nanoparticles (IONP-LPrA2). PC cells were cultured with leptin and allow to form primary and secondary tumorspheres, enriched in PCSC. Tumorspheres were treated with the compounds described for 7-14 days. Number and size of tumorspheres were recorded, and expression of leptin receptor, OB-R and secretion of leptin were determined by Western blot (WB) and ELISA, respectively. Additionally, the levels of Notch, PCSC and EMT markers, pluripotency associated genes (Oct-4, Sox-2 and Nanog) and ATP-binding cassette transporters (ABCB1, ABCG2 and ABCC5) were determined using flow cytometry and WB. Results: PC cells expressed Leptin/OB-R system, suggesting an autocrine role in PC progression and chemoresistance. Leptin induced the formation of primary and secondary tumorspheres and increased their expression of Notch, EMT and pluripotency markers. Additionally, chemotherapeutics induced PC survival and the expression of ATP-binding cassette transporters in tumorspheres that was reinforced by leptin actions. Blockade of leptin signaling via IONP-LPrA2 and Notch activation via DAPT reduced leptin-induced molecular effects, PCSC and tumorsphere growth. Conclusion: Present data suggest that obesity, through leptin-induced Notch signaling, could increase chemoresistance in PC patients. Inhibition of leptin-Notch axis may be novel therapeutic strategy for PC, which may improve chemotherapeutic efficacy and increase survival in PC patients, particularly in obese contexts. Acknowledgements: this work has been supported by a Pilot Project Award from MSM/Tuskegee University/UAB Cancer Center partnership grant 5U54CA118638; PC SPORE Grant from UAB to RRGP, and facilities and support services at Morehouse School of Medicine (1G12RR026250-03; NIH RR 03034 and 1C06 RR18386). Citation Format: Adriana Harbuzariu, Crystal C. Lipsey, Ruben R. Gonzalez-Perez. Leptin-Notch crosstalk axis: A novel target for pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3544. doi:10.1158/1538-7445.AM2017-3544

Abstract 1849: The role of leptin signaling in the promotion of obesity-associated tumorigenesis and cancer stem cell characteristics in a transgenic mouse model of basal-like breast cancer

Abstract Background: Epidemiological studies have linked obesity to a greater risk of breast cancer-specific mortality. This association may be mediated in part by enhanced cancer stem cell (CSC) enrichment, as CSCs are thought to be the primary drivers of tumor initiation, growth, and metastasis. We and others have have demonstrated that obesity promotes CSC enrichment in pre-clinical models of basal-like breast cancer, but only when leptin signaling is present. These findings, coupled with evidence that elevated serum leptin and breast tumor leptin receptor expression are linked to a worse breast cancer prognosis, suggest that leptin-induced CSC enrichment may be a key contributor to obesity-associated breast cancer progression. Methods: MMTV-Wnt-1 transgenic mice, which develop spontaneous basal-like mammary tumors, were fed a control diet (10% kcal from fat) or a diet-induced obesity regimen (DIO, 60% kcal from fat). Mice were euthanized when tumors reached 1.5 cm in diameter. RNA sequencing was performed on 4 tumors/diet group. Serum hormones and cytokines were measured via luminex-based assay. ALDH activity, a putative CSC marker, was quantified by an ALDH Activity Assay Kit (abcam). Quantitative RT-PCR was used to determine expression of CSC-related genes, leptin, and the leptin receptor. Two mammary tumor cell lines isolated from the MMTV-Wnt-1 model (M-Wnt and E-Wnt cells) and human MDA-MB-231 were exposed in vitro to pooled serum from DIO or control mice (2% concentration), and cell viability, migration, invasion and expression of CSC related genes were measured. Results: Tumor incidence and growth rate were greater in DIO versus control mice. RNA sequencing revealed an upregulation in a CSC gene signature in tumors from DIO versus control mice. Significant upregulation in several of these genes, including aldh1a, oct4, twist1, twist2, and akt3, was confirmed by qRT-PCR (P &amp;lt; 0.05). ALDH activity in the DIO (relative to control) tumors was also significantly increased (P &amp;lt; 0.05). Serum levels and mammary tissue expression of leptin and tumor expression of the leptin receptor were significantly elevated in DIO versus control mice (P &amp;lt; 0.05). Exposure to serum from DIO mice significantly increased (relative to control) M-Wnt, E-Wnt, and MDA-MB-231 cell viability, migration, invasion, and expression of CSC-related genes in vitro (P &amp;lt; 0.05). The role of leptin signaling in these effects and in vitro measures of CSC enrichment will be explored through additional in experiments. Conclusions: Obesity promotes MMTV-Wnt-1 mammary tumor incidence and growth rate, possibly via CSC enrichment. Preliminary findings suggest increased leptin signaling may underlie obesity-associated CSC enrichment and may contribute to the breast cancer burden in obese women. Citation Format: Subreen A. Khatib, Laura W. Bowers, Emily L. Rossi, Shannon B. McDonell, Claire G. Lineberger, David A. Cavazos, Linda A. deGraffenried, Stephen D. Hursting. The role of leptin signaling in the promotion of obesity-associated tumorigenesis and cancer stem cell characteristics in a transgenic mouse model of basal-like breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1849. doi:10.1158/1538-7445.AM2017-1849

Impaired steroidogenesis in the testis of leptin-deficient mice (ob/ob -/-)

The obesity and its comorbidities, including resistance to leptin, impacts the reproductive function. Testes express leptin receptors in the germ cells and Leydig cells. Then, leptin-deficient animals are obese and infertile. We aimed to evaluate the structure and steroidogenic pathway of the testis of deficient leptin mice. Three months old male C57BL/6 mice (wild-type, WT) and deficient leptin (ob/ob) mice had their testes dissected and prepared for analyses. Compared to the WT group, the ob/ob group showed a greater body mass with smaller testes, and alterations in the germinative epithelium: fewer spermatogonia, spermatocytes, and spermatids. The Sertoli cells and the germ cells showed condensed nuclei and nuclear fragmentation indicating cell death, in agreement with a low expression of the proliferating cell nuclear antigen and a high expression of Caspase3. In the ob/ob group, the sperm was absent in the seminiferous tubules, and the steroidogenic pathway was compromised (low 3Beta hydroxysteroid dehydrogenase and steroidogenic acute regulatory protein). Further, all hormone receptors involved in the testicular function were down expressed (androgen, estrogen, follicle-stimulating, luteinizing, aromatase, and nicotinamide adenine dinucleotide phosphate). In conclusion, the findings indicate significant morphological, hormonal and enzymatic changes in the testis of the ob/ob mice. The shifts in the enzymatic steroidogenic pathway and the enzymes related to spermatic activity support the insights about the failures in the fertility of these animals. The study provides new evidence and contributes to the understanding of how the lack of leptin and obesity might negatively modulate the testicular function leading to infertility.

Leptin receptor antagonism of iNKT cell function: a novel strategy to combat multiple myeloma.

A hallmark of bone marrow changes with aging is the increase in adipocyte composition, but how this impacts development of multiple myeloma (MM) is unknown. Here, we report the role of the adipokine leptin as master regulator of anti-myeloma tumor immunity by modulating the invariant natural killer T (iNKT) cell function. A marked increase in serum leptin levels and leptin receptor (LR) expression on iNKT cells in MM patients and the 5T33 murine MM model was observed. MM cells and leptin synergistically counteracted anti-tumor functionality of both murine and human iNKT cells. In vivo blockade of LR signaling combined with iNKT stimulation resulted in superior anti-tumor protection. This was linked to persistent IFN-γ secretion upon repeated iNKT cell stimulation and a restoration of the dynamic antigen-induced motility arrest as observed by intravital microscopy, thereby showing alleviation of iNKT cell anergy. Overall our data reveal the LR axis as novel therapeutic target for checkpoint inhibition to treat MM.

Leptin acts on neoplastic behavior and expression levels of genes related to hypoxia, angiogenesis, and invasiveness in oral squamous cell carcinoma.

Leptin, one of the main hormones controlling energy homeostasis, has been associated with different cancer types. In oral cancer, its effect is not well understood. We investigated, through in vitro and in vivo assays, whether leptin can affect the neoplastic behavior of oral squamous cell carcinoma. Expression of genes possibly linked to the leptin pathway was assessed in leptin-treated oral squamous cell carcinoma cells and also in tissue samples of oral squamous cell carcinoma and oral mucosa, including leptin, leptin receptor, hypoxia-inducible factor 1-alpha, E-cadherin, matrix metalloproteinase-2, matrix metalloproteinase-9, Col1A1, Ki67, and mir-210. Leptin treatment favored higher rates of cell proliferation and migration, and reduced apoptosis. Accordingly, leptin-treated oral squamous cell carcinoma cells show decreased messenger RNA caspase-3 expression, and increased levels of E-cadherin, Col1A1, matrix metalloproteinase-2, matrix metalloproteinase-9, and mir-210. In tissue samples, hypoxia-inducible factor 1-alpha messenger RNA and protein expression of leptin and leptin receptor were high in oral squamous cell carcinoma cases. Serum leptin levels were increased in first clinical stages of the disease. In animal model, oral squamous cell carcinoma-induced mice show higher leptin receptor expression, and serum leptin level was increased in dysplasia group. Our findings suggest that leptin seems to exert an effect on oral squamous cell carcinoma cells behavior and also on molecular markers related to cell proliferation, migration, and tumor angiogenesis.

Imbalance in leptin-adiponectin levels and leptin receptor expression as chief contributors to triple negative breast cancer progression in Northeast India

BackgroundTriple-Negative breast cancer (TNBC), accounts for a large percentage of breast cancer cases in India including Northeast India. TNBC has an unclear molecular aetiology and hence limited targeted therapies. Human breast is comprised of glandular, ductal, connective, and adipose tissues. Adipose tissue is composed of adipocytes. The adipocytes apart from being energy storage depots, are also active sources of adipocytokines and/or adipokines. The role of adipokines in breast cancer including TNBC has been sporadically documented. Two adipokines in particular, leptin and adiponectin, have come to be recognized for their influence on breast cancer risk and tumour biology. Therefore, the aim of this study was to understand the association of differential expression of critical adipokines and associated cellular mechanism in the susceptibility and severity of TNBC in northeast Indian population. Materials and methodsWe collected 68 TNBC and 63 controls cases and examined for serum leptin and adiponectin levels using enzyme linked immunosorbent assay (ELISA). Leptin Receptor (Ob-R) mRNA expression was determined by real-time polymerase chain reaction (RT-PCR) assay. Differential Ob-R mRNA expression and correlation with cancer stem cell (CSC) markers was evaluated, and correlated with severity. ResultsThe serum leptin levels were significantly associated with TNBC severity, while the adiponectin levels were comparative. The serum leptin levels correlated inversely with the adiponetin levels. Serum leptin levels were unaffected with difference in parity. The difference in leptin levels in pre and post menopausal cases were found to be statistically non-significant. Higher leptin levels were also found to be associated obesity, mortality and recurrence. Obesity was found to be a factor for TNBC pathogenesis and severity. Increased Ob-R mRNA expression was associated with TNBC, significantly with TNBC severity, and was significantly higher in obese patients with higher grade TNBC cases. The Ob-R gene mRNA expression was significantly higher in the obese TNBC cases showing recurrence or mortality. The higher Ob-R gene mRNA expression correlated significantly with higher serum leptin levels and lower serum adiponectin levels in TNBC cases. The Ob-R mRNA expression with associated with modulation of CSC oct4 and nanog. ConclusionsIn conclusion, the present study is first of its kind on TNBC from northeast India, indicates that adipocytokines does play a role in TNBC pathogenesis. Thus, the understanding of molecular mechanisms of both leptin and adiponectin and their interplay in TNBC offer the prospects for new therapeutic approaches targeting similar signalling pathways.

Leptin Increases Blood Pressure Acting via Transient Receptor Potential (TRP) Channels in the Carotid Body

RationaleObesity leads to cardiovascular morbidity and mortality acting via multiple mechanisms including hypertension and obstructive sleep apnea. Obesity leads to high levels of adipokine leptin. Increased leptin levels have been previously reported in sleep apnea and implicated in increased sympathetic activity and the pathogenesis of hypertension. However, mechanisms of the effects of leptin on blood pressure are unclear. The carotid bodies (CB) express leptin receptor (LepR), but the mechanisms and consequences of leptin action in CB are unknown. We have previously demonstrated that leptin enhances carotid sinus nerve activity in response to hypoxia and this effect is abolished by non‐selective blockers of transient receptor potential (TRP) channels (Shirahata et al., 2015). We hypothesized that high levels of circulating leptin signal via LepR in CB leading to hypertension and that leptin's effect is mediated via TRP channels.Methods1) Male C57BL/6J mice (n=6) were implanted with telemetry in the left femoral artery for blood pressure monitoring at baseline, during leptin infusion (120ug/day for 3 days via a SC pump) before and after CB denervation; 2) LepR deficient db/db mice were implanted with telemetry; blood pressure measurements were performed followed by infection with adenovirus carrying the LepR gene (Ad‐LepR, n=5) or luciferase (control, Ad‐Luc, n=5) followed by BP measurements; 3) Expression of different TRP channels was measured in CB of wildype C57BL/6J, leptin deficient ob/ob mice and LepR deficient db/db mice; 4) TRP channel expression was measured in db/db mice infected with Ad‐LepR vs Ad‐Luc; 5) blood pressure monitoring was performed in male C57BL/6J mice (n= 9) at baseline, during leptin infusion with or without Trpm7 inhibitor, FTY720 (10mg/kg, sc, n=3) for 24 hrs.Results1) In mice with intact CB, leptin increased mean arterial pressure by 13 mm Hg during the day and by 16 mm Hg at night (p = 0.003 for the effect of leptin). CB denervation completely abolished leptin‐induced hypertension (p &lt; 0.001). 2) wildtype C57BL/6J mice showed significantly higher CB expression of Trpm7 compared to ob/ob and db/db mice; 3) LepR expression in CB of db/db mice dramatically increased Trpm7 expression; 4) Trpm7 inhibitor FTY720 abolished leptin‐induced hypertension.ConclusionsLeptin increases blood pressure by acting via LepR and downstream Trpm7 channels in the CB.Support or Funding InformationHL133100, HL128970

Erratum: Uterine artery leptin receptors during the ovarian cycle and pregnancy regulate angiogenesis in ovine uterine artery endothelial cells.

Leptin regulates body weight, reproductive functions, blood pressure, endothelial function, and fetoplacental angiogenesis. Compared to the luteal phase, the follicular phase and pregnancy are physiological states of elevated estrogen, angiogenesis, and uterine blood flow (UBF). Little is known concerning regulation of uterine artery (UA) angiogenesis by leptin and its receptors. We hypothesized that (1) ex vivo expression of leptin receptors (LEPR) in UA endothelium (UAendo) and UA vascular smooth muscle (UAvsm) is elevated in pregnant versus nonpregnant (Luteal and Follicular) sheep; (2) in vitro leptin treatments differentially modulate mitogenesis in uterine artery endothelial cells from pregnant (P-UAECs) more than in nonpregnant (NP-UAECs) ewes; and (3) LEPR are upregulated in P-UAECs versus NP-UAECs in association with leptin activation of phospho-STAT3 signaling. Local UA adaptations were evaluated using a unilateral pregnant sheep model where prebreeding uterine horn isolation (nongravid) restricted gravidity to one horn. Immunolocalization revealed LEPR in UAendo and UAvsm from pregnant and nonpregnant sheep. Contrary to our hypothesis, western analysis revealed that follicular UAendo and UAvsm LEPR were greater than luteal, nongravid, gravid, and control pregnant. Compared to pregnant groups, LEPR were elevated in renal artery endothelium of follicular and luteal sheep. Leptin treatment significantly increased mitogenesis in follicular phase NP-UAECs and P-UAECs, but not luteal phase NP-UAECs. Although UAEC expression of LEPR was similar between groups, leptin treatment only activated phospho-STAT3 in follicular NP-UAECs and P-UAECs. Thus, leptin may play an angiogenic role particularly in preparation for the increased UBF during the periovulatory period and subsequently to meet the demands of the growing fetus.