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Obesity is associated with increased risk and worse prognosis of many tumours including those of the breast and of the esophagus. Adipokines released from the peritumoural adipose tissue promote the metastatic potential of cancer cells, suggesting the existence of a crosstalk between the adipose tissue and the surrounding tumour. Mitochondrial Ca 2+ signaling contributes to the progression of carcinoma of different origins. However, whether adipocyte-derived factors modulate mitochondrial Ca 2+ signaling in tumours is unknown. Here, we show that conditioned media derived from adipose tissue cultures (ADCM) enriched in precursor cells impinge on mitochondrial Ca 2+ homeostasis of target cells. Moreover, in modulating mitochondrial Ca 2+ responses, a univocal crosstalk exists between visceral adipose tissue-derived preadipocytes and esophageal cancer cells, and between subcutaneous adipose tissue-derived preadipocytes and triple-negative breast cancer cells. An unbiased metabolomic analysis of ADCM identified creatine and creatinine for their ability to modulate mitochondrial Ca 2+ uptake, migration and proliferation of esophageal and breast tumour cells, respectively., (© 2024. The Author(s).)

Adipose tissue (AT) is composed of a heterogeneous population which comprises both progenitor and differentiated cells. This heterogeneity allows a variety of roles for the AT, including regenerative functions. In fact, autologous AT is commonly used to repair soft tissue defects, and its cryopreservation could be a useful strategy to reduce the patient discomfort caused by multiple harvesting procedures. Our work aimed to characterize the cryopreserved AT and to validate its storage for up to three years for clinical applications. AT components (stromal vascular fraction-SVF and mature adipocytes) were isolated in fresh and cryopreserved samples using enzymatic digestion, and cell viability was assessed by immunofluorescence (IF) staining. Live, apoptotic and necrotic cells were quantified using cytometry by evaluating phosphatidylserine binding to fluorescent-labeled Annexin V. A multiparametric cytometry was also used to measure adipogenic (CD34+CD90+CD31-CD45-) and endothelial (CD34+CD31+CD45-) precursors and endothelial mature cells (CD34-CD31+CD45-). The maintenance of adipogenic abilities was evaluated using in vitro differentiation of SVF cultures and fluorescent lipid staining. We demonstrated that AT that is cryopreserved for up to three years maintains its differentiation potential and cellular composition. Given our results, a clinical study was started, and two patients had successful transplants without any complications using autologous cryopreserved AT.

We describe adipose stromal/stem cells (ASCs) in the structural/functional context of the adipose tissue (AT) stem niche (adiponiche), including cell-cell interactions and the microenvironment, and emphasize findings obtained in humans and in lineage-tracing models. ASCs have distinctive markers, 'colors', and anatomical 'locations' which influence their functions. Each adiponiche component can become impaired, thereby contributing to the pathological AT alterations seen in obesity and metabolic diseases. We discuss adiposopathy with a focus on adiponiche dysfunction, and underline the mechanisms that control AT expansion and energy balance. Better understanding of adiponiche regulation and ASC features could help to identify therapeutic targets that favor weight loss and counteract weight regain, and also contribute to innovative strategies for regenerative medicine., Competing Interests: Declaration of interests The authors declare no conflicts of interest., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Osteoarthritis (OA) is one of the most common joint disorders. Evidence suggests that the infrapatellar fat pad (IFP) is directly involved in OA pathology. However, a comparison between OA versus non-OA IFP is still missing. Thus, the aim of this study was to compare IFP molecular, adipocytes and extracellular matrix characteristics of patients affected by OA, and patients undergoing anterior cruciate ligament (ACL) reconstruction. We hypothesized that not only inflammation but also changes in adipocytes and extracellular matrix (ECM) composition might be involved in OA pathogenesis. Fifty-three patients were enrolled. IFP biopsies were obtained, evaluating: (a) lymphocytic infiltration and vascularization; (b) adipocytes area and number; (c) adipo-cytokines and extracellular matrix gene expression levels; (d) IL-6 and VEGF protein production; (e) collagen fibers distribution. OA IFP was more inflamed and vascularized compared to ACL IFP. OA IFP adipocytes were larger and numerically lower (1.3-fold) than ACL IFP adipocytes. An increase of gene expression of typical white adipose tissue genes was observed in OA compared to ACL IFP. Collagen-types distribution was different in the OA IFP group compared to controls, possibly explaining the change of the biomechanical characteristics found in OA IFP. Statistical linear models revealed that the adipocyte area correlated with BMI in the OA group. In conclusion, inflammation and fibrotic changes of OA IFP could represent novel therapeutic targets to counteract OA.

Osteoarthritis (OA) is the most common form of joint disease and a major cause of pain and disability in the adult population. Interestingly, there are patients with symptomatic OA displaying pain, while patients with asymptomatic OA that do not experience pain but show radiographic signs of joint damage. Pain is a complex experience integrating sensory, affective, and cognitive processes related to several peripheral and central nociceptive factors besides inflammation. During the last years, the role of infrapatellar fat pad (IFP), other than the synovial membrane, has been investigated as a potential source of pain in OA. Interestingly, new findings suggest that IFP and synovial membrane might act as a functional unit in OA pathogenesis and pain. The present review discuss the role of IFP and synovial membrane in the development of OA, with a particular focus on pain onset and the possible involved mediators that may play a role in OA pathology and pain mechanisms. Inflammation of IFP and synovial membrane may drive peripheral and central sensitization in KOA. Since sensitization is associated with pain severity in knee OA and may potentially contribute to the transition from acute to chronic, persistent pain in knee OA, preventing sensitization would be a potentially effective and novel means of preventing worsening of pain in knee OA.

Peritumoral microenvironment affects cancer development and chemoresistance, and visceral adipose tissue may play a critical role. We aimed to identify depot-specific adipose characteristics associated with carcinogenesis and resistance to neoadjuvant therapy in esophageal adenocarcinoma (EAC). We analyzed: (i) the peritumoral adipose tissue of rats following the induction of esophageal carcinogenesis; (ii) the peritumoral and distal (omental) adipose tissue of patients affected by EAC; (iii) adipose-derived stem cells (ADSC) isolated from healthy patients and treated with conditioned medium (CM), collected from tumoral and adipose tissue of patients with EAC. In peritumoral adipose tissue of rats, CD34, CD31 and vascular endothelial growth factor (VEGF) expression increased progressively during EAC development. In patients with EAC, expression of CD34, CD45, CD90 and nucleostemin (NSTM) was higher in peritumoral than in distal adipose tissue and decreased in the presence of neoadjuvant therapy. Moreover, expression of NSTM, octamer-binding transcription factor 4 (OCT-4) and VEGF was higher in peritumoral (but not in distal) adipose tissue of chemoresistant patients. In ADSC, treatment with peritumoral adipose tissue CM increased the adipogenic potential and the expression of CD34, CD90, NSTM and OCT-4. These effects were similar to those induced by cancer-derived CM, but were not observed in ADSC treated with distal adipose tissue CM and were partially reduced by a leptin antagonist. Last, ADSC treated with peritumoral CM of chemoresistant patients displayed increased expression of NSTM, OCT-4, leptin, leptin receptor, alpha-smooth muscle actin (α-SMA), CD34 and VEGF. These results suggest that peritumoral adipose tissue may promote, by paracrine signaling, the expression of depot-specific factors associated with therapeutic resistance., (© 2017 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.)

Objective: The infrapatellar fat pad (IFP) is considered a local producer of adipocytokines, suggesting a potential role in OA. The objective of this study was to evaluate the histopathological and molecular characteristics of OA IFPs compared with controls., Methods: The histopathological characteristics of IFPs were evaluated in patients undergoing total knee replacements and in control patients (without OA), considering the following parameters: presence of inflammatory cells, vascularization, adipose lobules dimension and thickness of the interlobular septa. Immunohistochemistry was performed to evaluate VEGF, monocyte chemotactic protein 1 (MCP-1) and IL-6 proteins. Quantitative real time PCR was performed to evaluate the expression levels of adipocytokines in the OA IFPs., Results: OA IFPs showed an increase in inflammatory infiltration, vascularization and thickness of the interlobular septa compared with controls. VEGF, MCP-1 and IL-6 proteins were higher in OA IFPs compared with in controls. Inflammatory infiltration, hyperplasia, vascularization and fibrosis were increased in OA IFP synovial membranes compared with in those of controls. VEGF protein levels were associated with an increased number of vessels in the OA IFPs, while MCP-1 and IL-6 protein levels were associated with higher grades of inflammatory infiltration. Leptin levels were positively correlated with adiponectin and MCP-1expression, while adiponectin positively correlated with peroxisome proliferative activated receptor gamma, MCP-1 and IFP vascularity. MCP-1 showed a positive correlation with peroxisome proliferative activated receptor gamma. IFP lobules dimensions were positively correlated with IL-6 expression and negatively with thickness of interlobular septa. VEGF mRNA levels were positively correlated with increased synovial vascularity., Conclusions: OA IFPs and synovial membranes are more inflamed, vascularized and fibrous compared with those of control patients (without OA)., (© The Author 2017. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: journals.permissions@oup.com)

Osteoarthritis is a common chronic joint disorder affecting older people. The knee is the major joint affected. The symptoms of osteoarthritis include limited range of motion, joint swelling, and pain causing disability. There are no disease modifying drugs available, and treatments are mainly focused on pain management. Total knee replacement performed at the end stage of the disease is considered the only cure available. It has been found that obese people have an increased risk to develop not only knee but also hand osteoarthritis. This supports the concept that adipose tissue might be related to osteoarthritis not only through overloading. As matter of fact, obesity induces a low grade systemic inflammatory state characterized by the production and secretion of several adipocytokines that may have a role in osteoarthritis development. Furthermore, hypertension, impaired glucose, and lipid metabolism, which are comorbidities associated with obesity, have been shown to alter the joint tissue homeostasis. Moreover, infrapatellar fat pad in the knee has been demonstrated to be a local source of adipocytokines and potentially contribute to osteoarthritis pathogenesis. Here, we discuss the role of systemic and local adipose tissue in knee osteoarthritis. J. Cell. Physiol. 232: 1971-1978, 2017. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

Context: Vitamin D accumulates in adipose tissue (AT), and vitamin D deficiency is frequent in obesity., Objective: We hypothesize that trafficking of vitamin D is altered in dysfunctional AT., Design, Patients, Settings: Fifty-four normal-weight and 67 obese males were recruited in a prospective study and randomly assigned to supplementation with 50 µg/wk 25-hydroxyvitamin-D3 or 150 µg/wk vitamin D3 for 1 year, raising dosage by 50% if vitamin D sufficiency [serum 25-hydroxyvitamin-D3 >50 nmol/L], was not achieved at 6 months; 97 subjects completed the study., Methods: Vitamin D3 and 25-hydroxyvitamin-D3 were quantified by HPLC-MS in control and insulin-resistant (IR) 3T3-L1 cells and subcutaneous AT (SAT) from lean and obese subjects, incubated with or without adrenaline; expression of 25-hydroxylase (Cyp27a1), 1α-hydroxylase (Cyp27b1), and vitamin D receptor (Vdr) was analyzed by real-time polymerase chain reaction., Results: In IR adipocytes, uptake of D3 and 25-hydroxyvitamin-D3 was higher, but, after adrenaline stimulation, the decrement in D3 and 25-hydroxyvitamin-D3 was stronger in control cells, which also showed increased expression of Cyp27a1 and Cyp27b1 and higher levels of 25-hydroxyvitamin-D3. In SAT from obese subjects, adrenaline-induced release of D3 and 25-hydroxyvitamin-D3 was blunted; in both IR cells and obese SAT, protein expression of β2-adrenergic receptor was reduced. Supplementation with 25-hydroxyvitamin-D3 was more effective in achieving vitamin D sufficiency in obese, but not in normal weight subjects., Conclusion: Dysfunctional AT shows a reduced catecholamine-induced release of D3 and 25-hydroxyvitamin-D3 and altered activity of vitamin D-metabolizing enzymes; for these reasons supplementation with 25-hydroxyvitamin-D3 is more effective in obese individuals., (Copyright © 2017 by the Endocrine Society)

A definitive relationship between adiposity and MP production is yet to be demonstrated. The aim of our study was to prospectively evaluate the levels of microparticles (MP) in a group of 20 III degree obese patients before and after weight loss. Plasma levels of annexin V-MP, endothelial-derived MP, platelet-derived MP (CD61+ and P-Selectin+), leukocyte-derived MP, tissue factor-bearing (TF+) and CD36+MP were prospectively measured in 20 patients with III degree obesity (BMI ≥ 40 kg/m(2)) before (T0) and 3 (T3) and 12 (T12) months after sleeve gastrectomy (SLG). Obese patients had lost 18 % of their body weight at T3 and 41 % at T12. We find that considering all MP, except for endothelial-derived MP, which had significantly decreased at T3, all MP subtypes had significantly decreased at T12. At T12, subjects showed a higher median level of all types of MP, except endothelial-derived MP, compared to T3, but without a statistically significant difference. The percentages of reduction of all the MP were significantly correlated with the percentage of reduction of BMI. The reductions of leukocyte-derived, TF+ and CD36+MP were significantly correlated with the reduction of leptin. Moreover, the reductions of leukocyte-derived and CD36+MP were significantly correlated with hs-CRP decrease. The decrease of BMI post-SLG in morbid obesity was matched with a decrease of circulating MP of endothelial, platelet, leukocyte origin, TF+ and CD36+. A trend of slight increase in all MP subtypes, except endothelial-derived, was detected 12 months after gastrectomy, indicating a possible underlying slow low-grade inflammatory/hypercoagulability state from adipose tissue before the potential overt weight gain.

Obesity is associated with cancer risk in esophageal adenocarcinoma (EAC). Adipose tissue directly stimulates tumor progression independently from body mass index (BMI), but the mechanisms are not fully understood. We studied the morphological, histological and molecular characteristics of peritumoral and distal adipose tissue of 60 patients with EAC, to investigate whether depot-specific differences affect tumor behavior. We observed that increased adipocyte size (a hallmark of obesity) was directly associated with leptin expression, angiogenesis (CD31) and lymphangiogenesis (podoplanin); however, these parameters were associated with nodal metastasis only in peritumoral but not distal adipose tissue of patients. We treated OE33 cells with conditioned media (CM) collected from cultured biopsies of adipose tissue and we observed increased mRNA levels of leptin and adiponectin receptors, as well as two key regulator genes of epithelial-to-mesenchymal transition (EMT): alpha-smooth muscle actin (α-SMA) and E-cadherin. This effect was greater in cells treated with CM from peritumoral adipose tissue of patients with nodal metastasis and was partially blunted by a leptin antagonist. Therefore, peritumoral adipose tissue may exert a direct effect on the progression of EAC by secreting depot-specific paracrine factors, and leptin is a key player in this crosstalk.

Insulin resistance and obesity are associated with a reduction of mitochondrial content in various tissues of mammals. Moreover, a reduced nitric oxide (NO) bioavailability impairs several cellular functions, including mitochondrial biogenesis and insulin-stimulated glucose uptake, two important mechanisms of body adaptation in response to physical exercise. Although these mechanisms have been thoroughly investigated in skeletal muscle and heart, few studies have focused on the effects of exercise on mitochondria and glucose metabolism in adipose tissue. In this study, we compared the in vivo effects of chronic exercise in subcutaneous adipose tissue of wild-type (WT) and endothelial NO synthase (eNOS) knockout (eNOS(-/-)) mice after a swim training period. We then investigated the in vitro effects of NO on mouse 3T3-L1 and human subcutaneous adipose tissue-derived adipocytes after a chronic treatment with an NO donor: diethylenetriamine-NO (DETA-NO). We observed that swim training increases mitochondrial biogenesis, mitochondrial DNA content, and glucose uptake in subcutaneous adipose tissue of WT but not eNOS(-/-) mice. Furthermore, we observed that DETA-NO promotes mitochondrial biogenesis and elongation, glucose uptake, and GLUT4 translocation in cultured murine and human adipocytes. These results point to the crucial role of the eNOS-derived NO in the metabolic adaptation of subcutaneous adipose tissue to exercise training., (© 2014 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.)

We recently demonstrated that testosterone dosing ameliorated the metabolic profile and reduced visceral adipose tissue (VAT) in a high-fat diet (HFD)-induced rabbit model of metabolic syndrome (MetS). We studied the effects of HFD and in vivo testosterone dosing on VAT function and the adipogenic capacity of rabbit preadipocytes isolated from VAT of regular diet (RD), HFD, and testosterone-treated HFD rabbits. VAT was studied by immunohistochemistry, western blot, and RT-PCR. Isolated rPADs were exposed to adipocyte differentiating mixture (DIM) to evaluate adipogenic potential. Adipocyte size was significantly increased in HFD VAT compared with RD, indicating adipocyte dysfunction, which was normalized by testosterone dosing. Accordingly, perilipin, an anti-lipolytic protein, was significantly increased in HFD VAT, when compared with other groups. HFD VAT was hypoxic, while testosterone dosing normalized VAT oxygenation. In VAT, androgen receptor expression was positively associated with mRNA expression of GLUT4 (SLC2A4) (insulin-regulated glucose transporter) and STAMP2 (STEAP4) (androgen-dependent gene required for insulin signaling). In testosterone-treated HFD VAT, STAMP2 mRNA was significantly increased when compared with the other groups. Moreover, GLUT4 membrane translocation was significantly reduced in HFD VAT, compared with RD, and increased by testosterone. In DIM-exposed preadipocytes from HFD, triglyceride accumulation, adipocyte-specific genes, insulin-stimulated triglyceride synthesis, glucose uptake, and GLUT4 membrane translocation were reduced compared with preadipocytes from RD and normalized by in vivo testosterone dosing. In conclusion, testosterone dosing in a MetS animal model positively affects VAT functions. This could reflect the ability of testosterone in restoring insulin sensitivity in VAT, thus counteracting metabolic alterations.

Context: The adipose tissue (AT), which is an endocrine organ, is linked to several metabolic abnormalities. Undercarboxylated osteocalcin (ucOCN) regulates insulin and adiponectin secretion., Objective: Our objective was to investigate the involvement of OCN in obesity and to evaluate, in vitro and ex vivo, the role of AT in the modulation of this endocrine circuit., Design, Patients, and Setting: This transversal study involved 83 male subjects, divided according to the World Health Organization body mass index classification, evaluated at Padova's Obesity Outpatient Clinic., Methods: OCN, both undercarboxylated (ucOCN) and carboxylated (cOCN) forms, was measured in serum by ELISA. OCN mRNA expression and protein production were measured by quantitative RT-PCR and immunohistochemistry during in vitro adipogenesis and in sc AT (SAT) and omental AT (OAT) from normal adult men. cOCN and ucOCN release by AT in a simple growth medium was verified by ELISA., Results: Overweight and obese patients had a lower ucOCN and ucOC/OCN ratio. In the whole cohort, ucOCN/OCN ratio was negatively correlated to body mass index (rho = -0.233; P < 0.05). OCN mRNA was present in SAT and OAT and during all stages of adipogenesis, with higher expression in the first steps. Immunohistochemistry confirmed the expression of OCN protein. Both SAT and OAT were able to release cOCN and ucOCN., Conclusions: Our data support a pathophysiological link between ucOCN and cOCN balance and obesity. OCN is present in the first phases of adipogenesis but also in human AT ex vivo. AT releases, in vitro, both ucOCN and cOCN, suggesting a possible link between AT and OCN in the regulation of metabolism.

The intermuscular adipose tissue (IMAT) is a depot of adipocytes located between muscle bundles. Several investigations have recently been carried out to define the phenotype, the functional characteristics, and the origin of the adipocytes present in this depot. Among the different mechanisms that could be responsible for the accumulation of fat in this site, the dysdifferentiation of muscle-derived stem cells or other mesenchymal progenitors has been postulated, turning them into cells with an adipocyte phenotype. In particular, muscle satellite cells (SCs), a heterogeneous stem cell population characterized by plasticity and self-renewal that allow muscular growth and regeneration, can acquire features of adipocytes, including the abilities to express adipocyte-specific genes and accumulate lipids. Failure to express the transcription factors that direct mesenchymal precursors into fully differentiated functionally specialized cells may be responsible for their phenotypic switch into the adipogenic lineage. We proved that human SCs also possess a clear adipogenic potential that could explain the presence of mature adipocytes within skeletal muscle. This occurs under some pathological conditions (i.e., primary myodystrophies, obesity, hyperglycemia, high plasma free fatty acids, hypoxia, etc.) or as a consequence of thiazolidinedione treatment or simply because of a sedentary lifestyle or during aging. Several pathways and factors (PPARs, WNT growth factors, myokines, GEF-GAP-Rho, p66(shc), mitochondrial ROS production, PKCβ) could be implicated in the adipogenic conversion of SCs. The understanding of the molecular pathways that regulate muscle-to-fat conversion and SC behavior could explain the increase in IMAT depots that characterize many metabolic diseases and age-related sarcopenia.

The aim of this study was to evaluate the morphometric changes of adipose tissue of lean and obese rats as assessed by computerized image analysis (IA) system in experimental conditions, with different degrees of adiposity. Moreover, to validate measures obtained by image analysis by correlation with direct measures of adiposity (body weight, epididimal fat, mean fat cell size and serum leptin). Finally to correlate these changes to expression of genes involved in lipid deposition and mobilization in adipose tissue. Lean (Fa/?) and genetically obese (fa/fa) Zucker rats were studied. Obese rats were food-restricted or treated with retinoic acid (ATRA) in order to reduce body weight and fat content. Moreover, gene expression of two key enzymes involved in fat metabolism (HSL and DGAT) were assessed in adipose tissue by RT-PCR. Our results show that HSL expression in adipose tissue was lower in obese compared to lean rats (1.47+/-0.02 vs 0.35+/-0.03, p<0.005) and was upregulated during food restriction in obese rats. DGAT expression was similar in lean and obese rats and was reduced by treatment with ATRA in obese rats. Tissue texture assessed by IA was significantly higher in lean compared to obese rats (23.2+/-0.6 vs 11.6+/-2.4%; p=0.01). Tissue structure highly correlated with adiposity in obese rats with different amount of body fat (area fraction vs epididimal fat depot: p=0.001). Distribution of measures for each sample, an index of spread of adipose tissue texture, as expressed by the standard deviation, correlated with adiposity (standard deviation vs epididimal fat depot: p=0.002) thus suggesting that adipose tissue texture increases its heterogeneity when adiposity is lower. This observation is in agreement with the hypothesis that the process of lipid mobilization from adipose tissue is not uniform, but a subpopulation of slimming adipocytes undergoes a complete release of their fat content while the rest of the tissue is much less affected. Moreover, image analysis system seems a reliable quantitative tool for assessment of adipose tissue texture.

Background: The aim of this study was to evaluate the relation between adiponectin and leptin, fat distribution, and insulin resistance in elderly men and women., Methods: 68 elderly participants (28 men and 40 women) aged 66-77 years, with body mass index (BMI) ranging from 19.83 to 37.18 kg/m2, participated in the study. In all participants, we evaluated BMI, waist and hip circumferences, sagittal abdominal diameter (SAD), fat mass (FM) by dual energy X-ray absorptiometry, fasting and 2-hour glucose, insulin, homeostasis model assessment of insulin resistance (HOMA), leptin, and adiponectin., Results: Elderly women had significantly higher circulating levels of adiponectin and leptin compared to men even after adjusting for age, FM, or waist circumference. In men and women, leptin was positively associated, whereas adiponectin was negatively associated, with BMI, indices of body fat distribution, as well as FM and FM%. Both fasting insulin and HOMA showed significant positive correlation with leptin and negative correlation with adiponectin in both sexes. In a step-wise multiple regression model with HOMA as the dependent variable and age, gender, waist circumference, FM, leptin, and adiponectin as independent variables, waist entered the regression first, explaining 19.7% of HOMA variance, leptin was second, and adiponectin was third, explaining each one an additional 10% of variance. In a multiple linear regression analysis, leptin and adiponectin alone explained up to 38% of HOMA variance., Conclusion: Leptin and adiponectin together seem to be strictly related to insulin resistance in elderly people, independently of body fat and body fat distribution.

Objective: Little is known about the physiological role and the regulation of uncoupling proteins-2 and -3 (UCP-2 and -3) in adipose tissue. We investigated whether the expression of UCP-2 and -3 in adipose tissue was affected by weight loss due to a biliopancreatic diversion (BPD) and related to the daily energy expenditure (24-h EE)., Design: Ten morbidly obese subjects (mean body mass index +/- s.e.m.=49.80 +/- 2.51 kg/m(2)) were studied before and 18+/-2 Months after BPD., Methods: We determined body composition using tritiated water and 24-h EE in a respiratory chamber. Adipose tissue UCP-2 and -3 mRNA, plasma insulin, glucose, free fatty acids (NEFA), free triiodothyronine (FT3), free thyroxine (FT4) and leptin were assayed before and after BPD., Results: BPD treatment resulted in a marked weight loss (P<0.001) mainly due to a fat mass reduction. A significant decrease in 24-h EE/fat-free mass (FFM) (P<0.05) and in UCP-2 (P<0.05) and UCP-3 (P<0.05) mRNA was observed. A significant reduction in plasma insulin, glucose, NEFA, FT3, FT4 and leptin was seen after BPD. The decline in plasma leptin and FFA was tightly correlated with the decrease in both UCP-2 and -3. A significant correlation was found between changes in FT3 and variations in 24-h EE (r=0.64, P<0.05). In a multiple-regression analysis changes in 24-h EE/FFM after BPD were significantly correlated with changes in UCP-3 expression (P<0.05)., Conclusion: These findings suggest that UCPs in adipose tissue may play a role in the reduction in 24-h EE observed in post-obese individuals.

Objective: Obesity-related insulin resistance is closely associated with visceral fat accumulation. Several adipocyte-secreted molecules have been implicated in the development of type 2 diabetes, among them, the recently discovered adiponectin and resistin proteins. Some of these adipocytokines are also present in the immune system, thus suggesting an intriguing functional connection., Research Methods and Procedures: We determined adiponectin and resistin expressions in visceral (VAT) and subcutaneous adipose tissue of lean and obese Zucker (fa/fa) rats using reverse-transcription polymerase chain reaction. Moreover, we analyzed the variations after body-weight reduction in food-restricted obese rats., Results: Resistin and adiponectin expression was significantly lower in VAT of genetically obese in comparison with lean rats; no differences were observed when subcutaneous adipose tissues of the same animals were compared. Weight loss resulted in an increase of adiponectin expression in VAT, whereas a further significant decrease in resistin mRNA level was observed. Resistin is also present and equally expressed in splenocytes of lean and obese rats., Discussion: Adiponectin and resistin are down-regulated in VAT of obese rats. Adiponectin expression is restored to normal levels after body-weight reduction, supporting its link with obesity-related insulin resistance. On the contrary, the further decrease of resistin mRNA after weight loss does not support the hypothesis that resistin may play a causative role in insulin resistance in obese rats. Moreover, we demonstrated the presence of resistin in immunocompetent cells in both humans and rats, thus adding another factor to the list of molecules that adipose tissue shares with the immune system.

Background: Our aim was to investigate the regulation of the gene expression of leptin in subcutaneous adipose tissue biopsies in morbid obesity before and after biliopancreatic diversion (BPD)., Methods: Longitudinal study in morbidly obese subjects investigated twice: before and 6 months after BPD. Fourteen morbidly obese women, 37+/-13 years old and with a body mass index of 51.6+/-8.2 kg/m2, were studied before and 6 months after BPD (40.6+/-8.0 kg/m2). Using reverse transcriptase polymerase chain reaction analysis, the mRNA expression of leptin was investigated in adipose tissue. Plasma leptin was measured by radioimmunoassay; plasma insulin was measured by microparticle enzyme immunoassay. Free fatty acids (FFA) were measured using a colorimetric kit., Results: A significant decrease in leptin mRNA level was observed in comparison with pretreatment in BPD patients (59+/-34 vs 143+/-85 arbitrary units, P<0.01). A strict relationship between adipose tissue leptin mRNA and plasma leptin either before (R2=0.80, P<0.0001) or after BPD (R2=0.86, P<0.0001) and between plasma FFA concentration and insulin either before (R2=0.65, P<0.001) or after BPD (R2=0.92, P<0.0001) was observed. Finally, a significant correlation was found between changes in FFA and insulin (R2=0.64, P<0.001), insulin and leptin (R2=0.88, P<0.0001), and insulin and leptin mRNA (R2=0.83, P<0.0001)., Conclusion: These data demonstrate a high correlation between leptin mRNA expression in adipose tissue and plasma leptin in postobese subjects after BPD. The significant relationship between both leptin mRNA and plasma leptin with insulin suggests that circulating insulin might regulate leptin expression. It might be hypothesized that plasma FFA concentration can act on the insulin secretion and subsequently on the leptin secretory pathway.

Obesity is a systemic disease frequently associated with important complications such as type 2 diabetes and cardiovascular diseases. It has also been proven that obesity is a disease associated with chronic low-grade systemic inflammation and that weight loss improves this low-grade chronic inflammatory condition. The P2X7 purinergic receptor (P2X7R), belonging to the family of the receptors for extracellular ATP, is a main player in inflammation, activating inflammasome and pro-inflammatory cytokine production. In this study, we evaluated the plasma levels of soluble P2X7R (sP2X7R) measured in a group of obese patients before and one year after bariatric surgery. Furthermore, we evaluated the relation of sP2X7R to inflammatory marker plasma levels. We enrolled 15 obese patients who underwent laparoscopic sleeve gastrectomy, evaluating anthropometric parameters (weight, height, BMI and waist circumference) before and after surgery. Moreover, we measured the plasma levels of inflammatory markers (CRP, TNFα and IL-6) before and after weight loss via bariatric surgery. The results of our study show that one year after bariatric surgery, obese patients significantly decrease body weight with a significant decrease in CRP, TNF-alfa and IL-6 plasma levels. Similarly, after weight loss, obese subjects showed a significant reduction in sP2X7R plasma levels. Moreover, before surgery, plasma levels of sP2X7R were inversely related with those of CRP, TNF-alfa and IL-6. Given the role of P2X7R in inflammation, we hypothesized that, in obese subjects, sP2X7R could represent a possible marker of chronic low-grade inflammation, hypothesizing a possible role as a mediator of obesity complications. [ABSTRACT FROM AUTHOR]

Insulin-like factor 5 (INSL5), a novel hormone secreted by the enteroendocrine cells of the distal colon, has been implicated in appetite and body weight regulation in animals given its orexigenic properties. We investigated basal INSL5 plasma levels in a group of morbidly obese subjects before and after laparoscopic sleeve gastrectomy. Furthermore, we analyzed the expression of INSL5 in human adipose tissue. Before bariatric surgery, obese subjects showed basal INSL5 plasma levels that were positively correlated with BMI, fat mass, and leptin plasma levels. After weight loss by laparoscopic sleeve gastrectomy, INSL5 plasma levels in obese subjects were significantly lower than those observed before surgery. Finally, we did not detect any expression of the INSL5 gene in human adipose tissue, both at the mRNA and protein levels. The present data show that subjects with obesity have INSL5 plasma levels positively correlating with adiposity markers. After bariatric surgery, INSL5 plasma levels decreased significantly, and this decrease was not directly due to the loss of adipose tissue since this tissue does not express INSL5. Considering the orexigenic properties of INSL5, the reduction of its plasma levels after bariatric surgery in obese subjects could participate in the still unclear mechanisms leading to appetite reduction that characterize bariatric surgery procedures. [ABSTRACT FROM AUTHOR]

Background: The development of obesity-related complications lies in the low-grade inflammatory state consequent to adipocyte dysfunction. The direct involvement of sex hormones in adipose tissue inflammation has been previously suggested, but the evidence is scarce. In this study, we evaluated the effects of sex steroids on the in-vitroexpression of inflammatory mediators in human-derived adipocytes before and after lipopolysaccharide (LPS) exposure. Methods: Human adipocytes were differentiated from the vascular stromal fraction of adipose tissue samples of subjects undergoing abdominoplasty. We evaluated MCP-1, IL-1β, IL-6, and TNF-α gene expression in the presence of the main sex steroids, testosterone (T), and 17β-estradiol (E). Furthermore, we analyzed the effects of adipocytes exposure to the non-aromatizable androgen dihydrotestosterone (DHT), together with the effects of adipocytes pre-incubation with the aromatase inhibitor anastrozole alone (A), and in combination with T (A/T) before incubation with LPS. Results: DHT, but not T, significantly enhanced the LPSinduction of MCP-1, IL-1β, IL-6, and TNF-α. Intriguingly, the exposure of adipocytes with A/T dramatically increased the LPS-induced expression of all considered inflammatory cytokines, even more than a hundred-fold. Conclusions: DHT and A/T dramatically enhance LPS-induced inflammatory cytokine expression in human-derived adipocytes. These results confirm the involvement of sex hormones in adipose tissue inflammation, suggesting a specific role for non-aromatizable androgens as the amplificatory sex hormones of the inflammatory response. [ABSTRACT FROM AUTHOR]

Extracellular ATP exerts important functions as an extracellular signaling molecule via the activation of specific P2 purinergic receptors (P2X and P2Y). We investigated the expression of the different P2 receptors and their possible functional activation in human adipocytes in primary culture. We performed molecular expression analysis of the P2 receptors in human mature adipocytes; examined their functional activation by different nucleotides evaluating [Ca2+]i modifications and IL-6 secretion, and determined the ability of adipocytes to release ATP in the extracellular medium. Human adipocytes express different P2X and P2Y receptors. Extracellular ATP elicited a rise in [Ca2+]i via the activation of P2X and P2Y receptor subtypes. Human adipocytes spontaneously released ATP in the extracellular medium and secreted IL-6 both at rest and after stimulation with ATP. This stimulatory effect of ATP on IL-6 secretion was inhibited by pre-incubation with apyrase, an ATP metabolizing enzyme. These results demonstrate that human adipocytes express different P2X and P2Y receptors that are functionally activated by extracellular nucleotides. Furthermore, human adipocytes spontaneously release ATP, which can act in an autocrine/paracrine fashion on adipocytes, possibly participating in the regulation of inflammatory cytokine release. Thus, P2 purinergic receptors could be a potential therapeutic target to contrast the inflammatory and metabolic complications characterizing obesity. [ABSTRACT FROM AUTHOR]

Determinants of resting energy expenditure (REE) in humans are still under investigation, especially the association with insulin resistance. Brown adipose tissue (AT) regulates energy expenditure through the activity of the uncoupling protein 1 (UCP1). White AT browning is the process by which some adipocytes within AT depots acquire properties of brown adipocytes ("brite" adipocytes) and it correlates with metabolic improvement. We analyzed determinants of REE in patients with obesity and assessed UCP1 expression as a "brite" marker in abdominal subcutaneous AT (SAT) and visceral omental AT (VAT). Clinical data, REE, free fat mass (FFM), and fat mass (FM) were determined in 209 patients with obesity. UCP1 , PPARG coactivator 1 alpha (PPARGC1A), transcription factor A, mitochondrial (TFAM), T-box transcription factor 1 (TBX1), and solute carrier family 27 member 1 (SLC27A1) expression was assayed in SAT and VAT samples, obtained during sleeve gastrectomy from 62 patients with obesity. REE and body composition data were also available for a subgroup of 35 of whom. In 209 patients with obesity a multiple regression model was computed with REE as the dependent variable and sex, waist, FFM, FM, homeostasis model assessment-insulin resistance (HOMA), interleukin-6 and High Density Lipoprotein-cholesterol as the independent variables. Only FFM, FM and HOMA were independently correlated with REE (r = 0.787, AdjRsqr = 0.602). In each patient VAT displayed a higher UCP1, PPARGC1A, TFAM, TBX1 , and SLC27A1 expression than SAT and UCP1 expression in VAT (UCP1 -VAT) correlated with Body Mass Index (BMI) (r = 0.287, p < 0.05). Introducing UCP1 -VAT in the multivariate model, we showed that FFM, HOMA, interleukin-6, High Density Lipoprotein-cholesterol, and UCP1 -VAT were independent factors correlated with REE (r = 0.736, AdjRsqr = 0.612). We confirmed that REE correlates with FFM, FM and HOMA in a large cohort of patients. Our results clearly showed that UCP1 -VAT expression was significantly increased in severe human obesity (BMI > 50 kg/m2) and that it behaved as an independent predictor of REE. Lastly, we suggest that an increased REE and browning in metabolically complicated severe obesity could represent an effort to counteract further weight gain. [ABSTRACT FROM AUTHOR]

Abstract The aim of this study was to analyze the magnetic resonance imaging (MRI) volumetric and morphometric characteristics of the infrapatellar fat pad (IFP) and the suprapatellar fat pad (SFP) in normal controls, moderate and end-stage osteoarthritis (OA) patients. Forty-four MRI images of the three groups were collected: a) 17 patients undergoing meniscectomy with Outerbridge score 0 (control group); b) 15 patients undergoing meniscectomy with Outerbridge score 3/4 (moderate OA group); and c) 12 patients undergoing total knee replacement (end-stage OA group). Volume, depth, femoral and tibial arch lengths of IFP were quantified. The hypointense IFP signals were also scored. The SFP volume, oblique, antero-posterior and cranio-caudal lengths were determined. IFP and SFP characteristics were compared between groups. A decrease of IFP volume, depth, femoral, and tibial arch lengths in moderate and end-stage OA compared to controls were observed. A difference in IFP hypointense signal was found between groups. No differences were found in SFP characteristics between the groups. In controls and moderate OA patients, correlations were found among the different MRI characteristics of both IFP and SFP, while in the end-stage OA group correlations were found only in SFP. We evidenced differences of the IFP MRI morphometric characteristics between the groups analyzed, supporting an important role of IFP in OA pathology and progression. On the contrary, no differences were highlighted in SFP analysis suggesting that this fat pad is not clearly involved in OA, probably due to its peculiar localization and different function. [ABSTRACT FROM AUTHOR]

Dysregulation of signaling pathways in adipose tissue leading to insulin resistance can contribute to the development of obesity-related metabolic disorders. Alström Syndrome, a recessive ciliopathy, caused by mutations in ALMS1, is characterized by progressive metabolic alterations such as childhood obesity, hyperinsulinemia, and type 2 diabetes. Here we investigated the role of Alms1 disruption in AT expansion and insulin responsiveness in a murine model for Alström Syndrome. A gene trap insertion in Alms1 on the insulin sensitive C57BL6/Ei genetic background leads to early hyperinsulinemia and a progressive increase in body weight. At 6 weeks of age, before the onset of the metabolic disease, the mutant mice had enlarged fat depots with hypertrophic adipocytes, but without signs of inflammation. Expression of lipogenic enzymes was increased. Pre-adipocytes isolated from mutant animals demonstrated normal adipogenic differentiation but gave rise to mature adipocytes with reduced insulin-stimulated glucose uptake. Assessment of whole body glucose homeostasis revealed glucose intolerance. Insulin stimulation resulted in proper AKT phosphorylation in adipose tissue. However, the total amount of glucose transporter 4 (SLC4A2) and its translocation to the plasma membrane were reduced in mutant adipose depots compared to wildtype littermates. Alterations in insulin stimulated trafficking of glucose transporter 4 are an early sign of metabolic dysfunction in Alström mutant mice, providing a possible explanation for the reduced glucose uptake and the compensatory hyperinsulinemia. The metabolic signaling deficits either reside downstream or are independent of AKT activation and suggest a role for ALMS1 in GLUT4 trafficking. Alström mutant mice represent an interesting model for the development of metabolic disease in which adipose tissue with a reduced glucose uptake can expand by de novo lipogenesis to an obese state. [ABSTRACT FROM AUTHOR]

Abstract: This review article focuses on the many metabolic actions of insulin at the level of muscle, liver and adipose tissue. In terms of pathogenetic mechanisms, the condition of insulin resistance is complex, as multiple genetic and environmental factors, among which an increasingly sedentary lifestyle associated with high-fat diet, mutually interact according to variable patterns in time in any given individual. It is well recognized that obesity (in particular abdominal obesity) favours the development of insulin resistance. Here we evaluate the impact of obesity and ectopic fat accumulation (visceral and hepatic) on insulin resistance at the level of different target organs, i.e., muscle, liver and adipose tissue. The roles of the gut and the liver, in particular of bile acids and gut microflora, are also discussed as possible determinants of energy balance and glucose metabolism. [Copyright &y& Elsevier]

Endocannabinoids (ECs) regulate energy balance by modulating hypothalamic circuits controlling food intake and energy expenditure. However, convincing evidence has accumulated indicating that the EC system is present also in peripheral tissues, in particular in adipose tissue. Fat cells produce and are targets of ECs. Glucose uptake and lipoprotein lipase (LPL) activity, lipogenesis and adipogenesis are stimulated by ECs through cannabinoid 1 (CB1) receptors. Moreover, CB1 activation leads to a decreased mitochondrial biogenesis and function through inhibition of endothelial nitric oxide synthase (eNOS). All these effects are blocked by the CB1 antagonist rimonabant, suggesting that the weight-reducing effect of CB1 blockade is due not only to the transient suppression of food intake and reduction of lipogenesis but also to an increased mitochondrial biogenesis and oxidative metabolism which counteracts the inhibitory effects of ECs, levels of which are increased in fat tissues of obese rodents and humans. This review focuses on the role of ECs in adipose tissue metabolism, adipokine production, and interactions between ECs and peroxisome proliferator-activated receptors (PPARs) during adipogenesis. [Copyright &y& Elsevier]