BACKGROUND: Currently, a significant number of miners are involved in mining operations at the Gejiu tin mine in Yunnan. This occupational setting is associated with exposure to dust particles, heavy metals, polycyclic aromatic hydrocarbons, and radioactive radon, thereby significantly elevating the risk of lung cancer. This study aims to investigate the involvement of leptin-mediated extracellular regulated protein kinase (ERK) signaling pathway in the malignant transformation of rat alveolar type II epithelial cells induced by Yunnan tin mine dust. METHODS: Immortalized rat alveolar cells type II (RLE-6TN) cells were infected with Yunnan tin mine dust at a concentration of 200 μg/mL for nine consecutive generations to establish the infected cell model, which was named R₂₀₀ cells. The cells were cultured normally, named as R cells. The expression of leptin receptor in both cell groups was detected using the Western blot method. The optimal concentration of leptin and mitogen-activated protein kinase kinase (MEK) inhibitor (U0126) on R₂₀₀ cells was determined using the MTT method. Starting from the 20th generation, the cells in the R group were co-cultured with leptin, while the cells in the R₂₀₀ group were co-cultured with the MEK inhibitor U0126. The morphological alterations of the cells in each group were visualized utilizing hematoxylin-eosin staining. Additionally, concanavalin A (ConA) was utilized to detect any morphological differences, and an anchorage-independent growth assay was conducted to assess the malignant transformation of the cells. The changes in the ERK signaling pathway in epithelial cells after the action of leptin were detected using the Western blot method. RESULTS: Both the cells in the R group and R₂₀₀ group express leptin receptor OB-R. Compared to the R₂₀₀ group, the concentration of leptin at 100 ng/mL shows the most significant pro-proliferation effect. The proliferation of R₂₀₀ cells infected with the virus is inhibited by 30 μmol/L U0126, and a statistically significant divergence was seen when compared to the control group (P<0.05). Starting from the 25th generation, the cell morphology of the leptin-induced R₂₀₀ group (R₂₀₀L group) underwent changes, leading to malignant transformation observed at the 30th generation. The characteristics of malignant transformation became evident by the 40th generation in the R₂₀₀L group. In contrast, the other groups showed agglutination of P40 cells, and the speed of cell aggregation increased with an increase in ConA concentration. Notably, the R₂₀₀L group exhibited faster cell aggregation compared to the U0126-induced R₂₀₀ (R₂₀₀LU) group. Additionally, the cells in the R₂₀₀L group were capable of forming clones starting from P30, with a colony formation rate of 2.25‰±0.5‰. However, no clonal colonies were observed in the R₂₀₀LU group and R₂₀₀ group. The expression of phosphorylated extracellular signal-regulated kinase (pERK) was enhanced in cells of the R₂₀₀L group. However, when the cells in the R₂₀₀L group were treated with U0126, a blocking agent, the phosphorylation level of pERK decreased. CONCLUSIONS Leptin can promote the malignant transformation of lung epithelial cells infected by mine dust, and the ERK signaling pathway may be necessary for the transformation of alveolar type II epithelial cells induced by Yunnan tin mine dust.
Rats ; Animals ; Alveolar Epithelial Cells/pathology* ; Dust ; Tin/adverse effects* ; Lung Neoplasms/pathology* ; Leptin/adverse effects* ; Receptors, Leptin ; China ; Signal Transduction ; Epithelial Cells/pathology* ; Mitogen-Activated Protein Kinase Kinases/adverse effects*

PURPOSE: This study aimed to investigate the clinical and metabolic determinants of circulating soluble leptin receptor (CSLR) and free leptin index (FLI) in pre-pubertal obese male children.METHODS: We conducted a preliminary cross-sectional study at three tertiary hospitals and one public primary school. Eighty obese male children without growth and developmental abnormalities aged 5–9 years were recruited. In these children, obesity was solely caused by excessive food intake, and not by acute illness, medications, endocrine abnormalities, or any syndrome. Body mass index (BMI), body fat mass, carbohydrate intake, fat intake, high density lipoprotein cholesterol level, low density lipoprotein cholesterol level, triglyceride level, and Homeostatic Model Assessment for Insulin Resistance are the potential determinants for leptin regulation, which is represented by CSLR level and FLI.RESULTS: Carbohydrate was the main source of energy. BMI and body fat mass had negative weak correlation with CSLR and positive weak correlation with FLI. Furthermore, carbohydrate intake was found to be independently associated with CSLR based on the results of the multiple linear regression analysis. Following an increase in carbohydrate intake, CSLR level decreased progressively without any negative peak.CONCLUSION: Leptin regulation in prepubertal obese male children is associated with body composition and dietary intake. Carbohydrate intake is useful for predicting CSLR. Lipid profiles and insulin resistance are not related to both CSLR and FLI. Treatment and prevention of leptin resistance in obese children should focus on reducing BMI, fat mass, and carbohydrate intake.
Adipose Tissue ; Body Composition ; Body Mass Index ; Child ; Cholesterol, HDL ; Cholesterol, LDL ; Cross-Sectional Studies ; Diet ; Eating ; Growth and Development ; Humans ; Insulin Resistance ; Leptin ; Linear Models ; Male ; Obesity ; Receptors, Leptin ; Tertiary Care Centers ; Triglycerides

The defective satiation signaling may contribute to the etiology of obesity. We investigated how dietary modification during maternal (pregnancy and lactation) and post-weaning affects obesity, insulin resistance (IR) and hypothalamic appetite responses in offspring in adulthood. Pregnant female SD rats were randomly allocated to either maternal high-fat diet (43% energy from fat) or control diet (12% energy from fat) until the end of suckling. After weaning for additional 4 weeks, half of the offsprings were continuously fed the same diet as the dam (C-C and H-H groups); the remainder received the counterpart diet (C-H and H-C groups). The long-term high-fat diet during maternal and post-weaning period (H-H group) led to susceptibility to obesity and IR through the significant increases of hypothalamic orexigenic genes compared to the maternal and post-weaning control diet group (C-C group). In contrast, the hypothalamic expression levels of anorexigenic genes, apolipoprotein E, leptin receptor, and activated signal transducer and activator of transcription protein 3 were significantly lower in H-H group with elevations in circulating insulin and leptin and body fat mass. However, dietary changes after weaning (H-C and C-H groups) partially modified these conditions. These results suggest that maternal and post-weaning diet conditions can potentially disrupt hypothalamic neuronal signal irrelevantly, which is essential for leptin's regulation of energy homeostasis and induce the risk of offspring to future metabolic disorders.
Adipose Tissue ; Animals ; Apolipoproteins ; Appetite* ; Diet ; Diet, High-Fat* ; Female ; Food Habits ; Homeostasis ; Humans ; Insulin ; Insulin Resistance ; Leptin* ; Neurons ; Obesity ; Pregnancy ; Rats* ; Receptors, Leptin ; Satiation ; Transducers ; Weaning

PURPOSE: High-fat (HF) feeding induces hypothalamic leptin resistance via the activation of toll-like receptor 4 (TLR4). TLR4 deficiency confers resistance to diet-induced obesity. Udenafil, an anti-impotence drug, inhibits TLR4 in airway epithelial cells in vitro. In this study, we evaluated whether udenafil suppressed the hypothalamic expression of TLR4 and reduced body weight. MATERIALS AND METHODS: The hypothalamic expression of TLR4, phosphodiesterase 5 (PDE5), nuclear factor-κB (NF-κB), and myeloid differentiation primary response gene 88 (Myd88) was analyzed by real-time polymerase chain reaction after treating mice for 2 days with udenafil (0, 12, 120, or 600 µg/d). Furthermore, the hypothalamic expression of TLR4, pro-opiomelanocortin (POMC), and neuropeptide Y (NPY) was analyzed after 9 days' treatment with udenafil and/or leptin. We also measured body weight and food intake following 9 days of udenafil and/or leptin treatment in control- and HF-fed mice. RESULTS: Udenafil suppressed hypothalamic TLR4 mRNA expression dose-dependently. The changes were associated with decreased PDE5, NF-κB, and Myd88 expression. Udenafil treatment for 9 days reduced body weight and caloric intake in HF-fed mice. This may have been associated with the suppression of NPY expression that was elevated by HF feeding. POMC expression was not affected by udenafil. However, udenafil did not augment the effects of leptin on the reduction of body weight and caloric intake in HF-fed mice. CONCLUSIONS: These results suggested that udenafil reduced body weight by suppressing hypothalamic TLR4 mRNA expression in HF-fed mice and the combination effect of udenafil and leptin was additive rather than synergistic.
Animals ; Body Weight ; Cyclic Nucleotide Phosphodiesterases, Type 5 ; Eating ; Energy Intake ; Epithelial Cells ; Hypothalamus ; In Vitro Techniques ; Leptin ; Mice ; Neuropeptide Y ; Obesity ; Pro-Opiomelanocortin ; Real-Time Polymerase Chain Reaction ; RNA, Messenger ; Toll-Like Receptor 4 ; Toll-Like Receptors

Accumulating evidence suggests that obesity is associated with chronic pain. However, whether obesity is associated with acute inflammatory pain is unknown. Using a well-established obese mouse model induced by a high-fat diet, we found that: (1) the acute thermal pain sensory threshold did not change in obese mice; (2) the model obese mice had fewer nociceptive responses in formalin-induced inflammatory pain tests; restoring the obese mice to a chow diet for three weeks partly recovered their pain sensation; (3) leptin injection induced significant phosphorylation of STAT3 in control mice but not in obese mice, indicating the dysmodulation of topical leptin-leptin receptor signaling in these mice; and (4) leptin-leptin receptor signaling-deficient mice (ob/ob and db/db) or leptin-leptin receptor pathway blockade with a leptin receptor antagonist and the JAK2 inhibitor AG 490 in wild-type mice reduced their nociceptive responses in formalin tests. These results indicate that leptin plays a role in nociception induced by acute inflammation and that interference in the leptin-leptin receptor pathway could be a peripheral target against acute inflammatory pain.
Animals ; Diet, High-Fat ; adverse effects ; Inflammation ; chemically induced ; metabolism ; Leptin ; metabolism ; pharmacology ; Male ; Mice ; Mice, Inbred C57BL ; Nociception ; drug effects ; physiology ; Nociceptive Pain ; etiology ; metabolism ; Obesity ; complications ; metabolism ; Pain Measurement ; Pain Threshold ; drug effects ; physiology ; Receptors, Leptin ; metabolism ; Signal Transduction ; drug effects ; physiology

Obesity has become a severe public health problem across the world, and seriously affects the health and life quality of human beings. Here we generated lepr and mc4r mutant zebrafish via the CRISPR/Cas9 technique, and performed morphological and functional characterizations of those mutants. We observed that there was no significant phenotypic difference between homozygous mutants and wild-type controls before 2.5 months post-fertilization (mpf). However, the adult leprand mc4rindividuals displayed increased food intake, heavier weight, and higher body fat percentage, the characteristics of obesity phenotypes. Blood glucose test showed that overfeeding induced significantly impaired glucose tolerance in adult leprand mc4rzebrafish. Furthermore, we analyzed 76 energy metabolism-related transcripts in leprand mc4rzebrafish livers by using real-time RT-PCR, and compared the results with the published microarray data of Lepmouse livers, and found that the changes in the expression of insulin/IGF signaling (IIS) pathway genes in leprzebrafish and Lepmouse were positively correlated, suggesting that the IIS pathway maintains functional conservation between zebrafish and mammals during the evolution of the obesity-regulating molecule network.
Animals ; CRISPR-Cas Systems ; Gene Knockout Techniques ; Insulin ; metabolism ; Leptin ; Mutation ; Obesity ; genetics ; Receptor, Melanocortin, Type 4 ; genetics ; Receptors, Leptin ; genetics ; Signal Transduction ; Zebrafish ; Zebrafish Proteins ; genetics

The cytokine-like hormone leptin is a classic adipokine that is secreted by adipocytes, increases with weight gain, and decreases with weight loss. Additional studies have, however, shown that leptin is also produced by skeletal muscle, and leptin receptors are abundant in both skeletal muscle and bone-derived mesenchymal (stromal) stem cells. These findings suggest that leptin may play an important role in muscle-bone crosstalk. Leptin treatment in vitro increases the expression of myogenic genes in primary myoblasts, and leptin treatment in vivo increases the expression of microRNAs involved in myogenesis. Bone marrow adipogenesis is associated with low bone mass in humans and rodents, and leptin can reduce marrow adipogenesis centrally through its receptors in the hypothalamus as well as directly via its receptors in bone marrow stem cells. Yet, central leptin resistance can increase with age, and low circulating levels of leptin have been observed among the frail elderly. Thus, aging appears to significantly alter leptin-mediated crosstalk among various organs and tissues. Aging is associated with bone loss and muscle atrophy, contributing to frailty, postural instability, and the incidence of falls. Therapeutic interventions such as protein and amino acid supplementation that can increase muscle mass and muscle-derived leptin may have multiple benefits for the elderly that can potentially reduce the incidence of falls and fractures.
Accidental Falls ; Adipocytes ; Adipogenesis ; Adipokines ; Aged ; Aging* ; Bone Marrow ; Frail Elderly ; Humans ; Hypothalamus ; In Vitro Techniques ; Incidence ; Insulin-Like Growth Factor I ; Leptin* ; Mesenchymal Stromal Cells ; MicroRNAs ; Muscle Development ; Muscle, Skeletal ; Muscular Atrophy ; Myoblasts ; Osteoporosis ; Receptors, Leptin ; Rodentia ; Sarcopenia ; Stem Cells ; Weight Gain ; Weight Loss

The C57BLKS/J-Lepr(db) mouse has a point mutation in the leptin receptor gene and is one of the most useful animal model for non-insulin dependent diabetes mellitus in human. Since the homozygote of C57BLKS/J-Lepr(db) mouse is infertile, detection of point mutation in the leptin receptor gene is important for efficient maintaining strains as well as mass production of homozygotes. To develop a rapid and efficient genotyping method for C57BLKS/J-Lepr(db) mouse, the tetra-primer amplification-refractory mutation system polymerase chain reaction (ARMS-PCR) was used. The 407 and 199 bp PCR products were amplified from normal (+/+) mice; while the 407 and 268 bp PCR products were amplified from homozygotes (db/db) mice; and the 407, 268, and 199 bp PCR products were amplified from heterozygotes (db/+) mice. This result showed that the tetra-primer ARMS-PCR analysis by us is suitable to detect point mutation of the leptin receptor gene. Taken together, our method will dramatically reduce animal use for maintenance of strains as well as production of homozygote in the C57BLKS/J-Lepr(db) strains.
Animals ; Diabetes Mellitus ; Heterozygote ; Homozygote ; Humans ; Leptin* ; Mice* ; Models, Animal ; Point Mutation ; Polymerase Chain Reaction ; Receptors, Leptin*

BACKGROUND/AIMS: The roles of the many bioactive peptides in the pathogenesis of celiac disease remain unclear. To evaluate the serum concentrations of insulin, ghrelin, adiponectin, leptin, leptin receptor, and lipocalin-2 in children with celiac disease who do and do not adhere to a gluten-free diet (GFD, intermittent adherence). METHODS: Prepubertal, pubertal, and adolescent celiac children were included in this study (74 girls and 53 boys on a GFD and 80 girls and 40 boys off of a GFD). RESULTS: Insulin levels in prepubertal (9.01±4.43 μIU/mL), pubertal (10.3±3.62 μIU/mL), and adolescent (10.8±4.73 μIU/mL) girls were higher than those in boys (5.88±2.02, 8.81±2.88, and 8.81±2.26 μIU/mL, respectively) and were neither age-dependent nor influenced by a GFD. Prepubertal children off of a GFD exhibited higher ghrelin levels than prepubertal children on a GFD. Adiponectin levels were not age-, sex- nor GFD-dependent. Adherence to a GFD had no effect on the expression of leptin, leptin receptor, and lipocalin-2. CONCLUSIONS: Adherence to a GFD had no influence on the adiponectin, leptin, leptin receptor, and lipocalin-2 concentrations in celiac children, but a GFD decreased highly elevated ghrelin levels in prepubertal children. Further studies are required to determine whether increased insulin concentrations in girls with celiac disease is suggestive of an increased risk for hyperinsulinemia.
Adiponectin* ; Adolescent ; Celiac Disease* ; Child* ; Diet, Gluten-Free* ; Female ; Ghrelin* ; Humans ; Hyperinsulinism ; Insulin* ; Leptin* ; Peptides ; Receptors, Leptin*

OBJECTIVETo investigate whether exogenous hydrogen sulfide (H2S) inhibits the high-glucose (HG)-induced injury by modulating leptin/leptin receptor (LEPR) signal pathway in human umbilical vein endothelial cells (HUVECs).

METHODSHUVECs were treated with 40 mmol/L glucose for 3-24 h, and the cell viability was examined by CCK-8 assay. The changes of cell morphology and the number of apoptotic cells were assessed by Hoechst 33258 nuclear staining followed by photofluorography. The intracellular levels of reactive oxygen species (ROS) was detected by DCFH-DA staining followed by photofluorography. Mitochondrial membrane potential (MMP) was determined by Rhodamine 123 (Rh123) staining and photofluorography. The expression levels of leptin and LEPR protein were measured by Western blotting.

RESULTSs The expression of leptin and LERP in HUVECs began to significantly increase at 3 h after HG exposure and reached the peak levels at 9 h (P<0.01). Pretreatment of HUVECs with 400 µmol/L sodium hydrosulfide (H2S donor) for 30 min inhibited HG-induced increase in leptin and leptin receptor expressions in HUVECs (P<0.01). Pretreatment of HUVECs with 400 µmol/L NaHS for 30 min or 50 ng/mL leptin antagonists (LA) for 1 h obviously alleviated HG-induced injury by increasing cell viability, decreasing cell apoptosis and lowering accumulation of intracellular ROS and MMP loss (P<0.01).

CONCLUSIONExogenous H2S protects against HG-induced injury by inhibiting leptin/LEPR pathway in HUVECs.

Apoptosis ; Cell Survival ; Cells, Cultured ; Glucose ; adverse effects ; Human Umbilical Vein Endothelial Cells ; drug effects ; metabolism ; Humans ; Hydrogen Sulfide ; pharmacology ; Leptin ; metabolism ; Membrane Potential, Mitochondrial ; Reactive Oxygen Species ; metabolism ; Receptors, Leptin ; metabolism ; Signal Transduction