Adipose Tissue Atrophy Research Articles

D-methionine improves cisplatin-induced anorexia and dyspepsia syndrome by attenuating intestinal tryptophan hydroxylase 1 activity and increasing plasma leptin concentration.

Cisplatin is a widely used antineoplastic drug. However, cisplatin-induced dyspepsia syndromes, including delayed gastric emptying, gastric distension, early satiety, nausea, and vomiting, often force patients to take doses lower than those prescribed or even refuse treatment. D-methionine has an appetite-enhancing effect and alleviates weight loss during cisplatin treatment. This work established a model of anorexia and dyspepsia symptoms with intraperitoneal injection of cisplatin (5mg/kg) once a week for three cycles. Presupplementation with or without D-methionine (300mg/kg) was performed. Orexigenic and anorexigenic hormones (ghrelin, leptin, and glucagon-like peptide-1), tryptophan hydroxylase 1 (TPH1), 5-hydroxytryptamine receptors (5-HT2C and 5-HT3 ), and hypothalamic feeding-related peptides were measured by immunohistochemistry staining, enzyme-linked immunosorbent assay, and real-time PCR assay. Cisplatin administration caused marked decrease in appetite and body weight, promoted adipose and fat tissue atrophy, and delayed gastric emptying and gastric distension, and D-methionine preadministration prior to cisplatin administration significantly ameliorated these side effects. Besides, cisplatin induced an evident increase in serum ghrelin level, TPH1 activity, and 5-HT3 receptor expression in the intestine and decreased plasma leptin levels and gastric ghrelin mRNA gene expression levels. D-methionine supplementation recovered these changes. The expression of orexigenic neuropeptide Y/agouti-related peptide and anorexigenic cocaine- and amphetamine-regulated transcript proopiomelanocortin neurons were altered by D-methionine supplementation in cisplatin-induced anorexia rats. D-methionine supplementation prevents cisplatin-induced anorexia and dyspepsia syndrome possibly by attenuating intestinal tryptophan hydroxylase 1 activity and increasing plasma leptin concentration. Therefore, D-methionine can be used as an adjuvant therapy for treating cisplatin-induced adverse effects.

Luseogliflozin increases beta cell proliferation through humoral factors that activate an insulin receptor- and IGF-1 receptor-independent pathway.

Sodium-glucose cotransporter 2 (SGLT2) inhibitors, which prevent the renal reabsorption of glucose, decrease blood glucose levels in an insulin-independent manner. We previously reported creating a mouse model of systemic inhibition of target receptors for both insulin and IGF-1 by treating animals with OSI-906, a dual insulin/IGF-1 receptor inhibitor, for 7days. The OSI-906-treated mice exhibited an increased beta cell mass, hepatic steatosis and adipose tissue atrophy, accompanied by hyperglycaemia and hyperinsulinaemia. In the present study, we investigated the effects of an SGLT2 inhibitor, luseogliflozin, on these changes in OSI-906-treated mice. We treated C57BL/6J male mice either with vehicle, luseogliflozin, OSI-906 or OSI-906 plus luseogliflozin for 7days, and phenotyping was performed to determine beta cell mass and proliferation. Subsequently, we tested whether serum-derived factors have an effect on beta cell proliferation in genetically engineered beta cells, mouse islets or human islets. SGLT2 inhibition with luseogliflozin significantly ameliorated hyperglycaemia, but not hyperinsulinaemia, in the OSI-906-treated mice. Liver steatosis and adipose tissue atrophy induced by OSI-906 were not altered by treatment with luseogliflozin. Beta cell mass and proliferation were further increased by SGLT2 inhibition with luseogliflozin in the OSI-906-treated mice. Luseogliflozin upregulated gene expression related to the forkhead box M1 (FoxM1)/polo-like kinase 1 (PLK1)/centromere protein A (CENP-A) pathway in the islets of OSI-906-treated mice. The increase in beta cell proliferation was recapitulated in a co-culture of Irs2 knockout and Insr/IR knockout (βIRKO) beta cells with serum from both luseogliflozin- and OSI-906-treated mice, but not after SGLT2 inhibition in beta cells. Circulating factors in both luseogliflozin- and OSI-906-treated mice promoted beta cell proliferation in both mouse islets and cadaveric human islets. These results suggest that luseogliflozin can increase beta cell proliferation through the activation of the FoxM1/PLK1/CENP-A pathway via humoral factors that act in an insulin/IGF-1 receptor-independent manner.

Leptin: Is It Thermogenic?

Animals that lack the hormone leptin become grossly obese, purportedly for 2 reasons: increased food intake and decreased energy expenditure (thermogenesis). This review examines the experimental evidence for the thermogenesis component. Analysis of the data available led us to conclude that the reports indicating hypometabolism in the leptin-deficient ob/ob mice (as well as in the leptin-receptor-deficient db/db mice and fa/fa rats) derive from a misleading calculation artefact resulting from expression of energy expenditure per gram of body weight and not per intact organism. Correspondingly, the body weight-reducing effects of leptin are not augmented by enhanced thermogenesis. Congruent with this, there is no evidence that the ob/ob mouse demonstrates atrophied brown adipose tissue or diminished levels of total UCP1 mRNA or protein when the ob mutation is studied on the inbred C57BL/6 mouse background, but a reduced sympathetic nerve activity is observed. On the outbred “Aston” mouse background, brown adipose tissue atrophy is seen, but whether this is of quantitative significance for the development of obesity has not been demonstrated. We conclude that leptin is not a thermogenic hormone. Rather, leptin has effects on body temperature regulation, by opposing torpor bouts and by shifting thermoregulatory thresholds. The central pathways behind these effects are largely unexplored.

JAK2-mutant hematopoietic cells display metabolic alterations that can be targeted to treat myeloproliferative neoplasms

AbstractIncreased energy requirement and metabolic reprogramming are hallmarks of cancer cells. We show that metabolic alterations in hematopoietic cells are fundamental to the pathogenesis of mutant JAK2–driven myeloproliferative neoplasms (MPNs). We found that expression of mutant JAK2 augmented and subverted metabolic activity of MPN cells, resulting in systemic metabolic changes in vivo, including hypoglycemia, adipose tissue atrophy, and early mortality. Hypoglycemia in MPN mouse models correlated with hyperactive erythropoiesis and was due to a combination of elevated glycolysis and increased oxidative phosphorylation. Modulating nutrient supply through high-fat diet improved survival, whereas high-glucose diet augmented the MPN phenotype. Transcriptomic and metabolomic analyses identified numerous metabolic nodes in JAK2-mutant hematopoietic stem and progenitor cells that were altered in comparison with wild-type controls. We studied the consequences of elevated levels of Pfkfb3, a key regulatory enzyme of glycolysis, and found that pharmacological inhibition of Pfkfb3 with the small molecule 3PO reversed hypoglycemia and reduced hematopoietic manifestations of MPNs. These effects were additive with the JAK1/2 inhibitor ruxolitinib in vivo and in vitro. Inhibition of glycolysis by 3PO altered the redox homeostasis, leading to accumulation of reactive oxygen species and augmented apoptosis rate. Our findings reveal the contribution of metabolic alterations to the pathogenesis of MPNs and suggest that metabolic dependencies of mutant cells represent vulnerabilities that can be targeted for treating MPNs.

Role of Mechanistic Target of Rapamycin and Autophagy in Alcohol-Induced Adipose Atrophy and Liver Injury

Chronic alcohol consumption induces adipose tissue atrophy. However, the mechanisms for how alcohol induces lipodystrophy and its impact on liver steatosis and injury are not fully elucidated. Autophagy is a highly conserved lysosomal degradation pathway, which regulates cellular homeostasis. Mice with autophagy deficiency in adipose tissue have impaired adipogenesis. However, whether autophagy plays a role in alcohol-induced adipose atrophy and how altered adipocyte autophagy contributes to alcohol-induced liver injury remain unclear. To determine the role of adipose autophagy and mechanistic target of rapamycin (mTOR) in alcohol-induced adipose and liver pathogenesis, we generated adipocyte-specific Atg5 knockout (KO), adipocyte-specific mTOR KO, adipocyte-specific Raptor KO, and adipocyte-specific tuberous sclerosis complex 1 KO mice by crossing floxed mice with Adipoq-Cre. The KO mice and their matched wild-type mice were challenged with chronic-plus-binge alcohol mouse model. Chronic-plus-binge alcohol induced adipose atrophy with increased autophagy and decreased Akt/mTOR signaling in epididymal adipose tissue in wild-type mice. Adipocyte-specific Raptor KO mice experienced exacerbated alcohol-induced steatosis, but neither adipocyte-specific mTOR nor adipocyte-specific tuberous sclerosis complex 1 KO mice exhibited similar detrimental effects. Adipocyte-specific Atg5 KO mice had increased circulating levels of fibroblast growth factor 21 and adiponectin and were resistant to alcohol-induced adipose atrophy and liver injury. In conclusion, autophagy deficiency in adipose tissue leads to reduced sensitivity to alcohol-induced adipose atrophy, which ameliorates alcohol-induced liver injury in mice.

Conditional Alox12b Knockout: Degradation of the Corneocyte Lipid Envelope in a Mouse Model of Autosomal Recessive Congenital Ichthyoses

Conditional Alox12b Knockout: Degradation of the Corneocyte Lipid Envelope in a Mouse Model of Autosomal Recessive Congenital Ichthyoses

Ferritin regulates organismal energy balance and thermogenesis

ObjectiveThe ferritin heavy/heart chain (FTH) gene encodes the ferroxidase component of the iron (Fe) sequestering ferritin complex, which plays a central role in the regulation of cellular Fe metabolism. Here we tested the hypothesis that ferritin regulates organismal Fe metabolism in a manner that impacts energy balance and thermal homeostasis. MethodsWe developed a mouse strain, referred herein as FthR26 fl/fl, expressing a tamoxifen-inducible Cre recombinase under the control of the Rosa26 (R26) promoter and carrying two LoxP (fl) sites: one at the 5′end of the Fth promoter and another the 3' end of the first Fth exon. Tamoxifen administration induces global deletion of Fth in adult FthR26Δ/Δ mice, testing whether FTH is required for maintenance of organismal homeostasis. ResultsUnder standard nutritional Fe supply, Fth deletion in adult FthR26Δ/Δ mice led to a profound deregulation of organismal Fe metabolism, oxidative stress, inflammation, and multi-organ damage, culminating in death. Unexpectedly, Fth deletion was also associated with a profound atrophy of white and brown adipose tissue as well as with collapse of energy expenditure and thermogenesis. This was attributed mechanistically to mitochondrial dysfunction, as assessed in the liver and in adipose tissue. ConclusionThe FTH component of ferritin acts as a master regulator of organismal Fe homeostasis, coupling nutritional Fe supply to organismal redox homeostasis, energy expenditure and thermoregulation.

Autophagy in Adipocyte Browning: Emerging Drug Target for Intervention in Obesity.

Autophagy, lipophagy, and mitophagy are considered to be the major recycling processes for protein aggregates, excess fat, and damaged mitochondria in adipose tissues in response to nutrient status-associated stress, oxidative stress, and genotoxic stress in the human body. Obesity with increased body weight is often associated with white adipose tissue (WAT) hypertrophy and hyperplasia and/or beige/brown adipose tissue atrophy and aplasia, which significantly contribute to the imbalance in lipid metabolism, adipocytokine secretion, free fatty acid release, and mitochondria function. In recent studies, hyperactive autophagy in WAT was observed in obese and diabetic patients, and inhibition of adipose autophagy through targeted deletion of autophagy genes in mice improved anti-obesity phenotypes. In addition, active mitochondria clearance through activation of autophagy was required for beige/brown fat whitening – that is, conversion to white fat. However, inhibition of autophagy seemed detrimental in hypermetabolic conditions such as hepatic steatosis, atherosclerosis, thermal injury, sepsis, and cachexia through an increase in free fatty acid and glycerol release from WAT. The emerging concept of white fat browning–conversion to beige/brown fat–has been controversial in its anti-obesity effect through facilitation of weight loss and improving metabolic health. Thus, proper regulation of autophagy activity fit to an individual metabolic profile is necessary to ensure balance in adipose tissue metabolism and function, and to further prevent metabolic disorders such as obesity and diabetes. In this review, we summarize the effect of autophagy in adipose tissue browning in the context of obesity prevention and its potential as a promising target for the development of anti-obesity drugs.

Immune response triggered by Trypanosoma cruzi infection strikes adipose tissue homeostasis altering lipid storage, enzyme profile and adipokine expression

Adipose tissue is a target of Trypanosoma cruzi infection being a parasite reservoir during the chronic phase in mice and humans. Previously, we reported that acute Trypanosoma cruzi infection in mice is linked to a severe adipose tissue loss, probably triggered by inflammation, as well as by the parasite itself. Here, we evaluated how infection affects adipose tissue homeostasis, considering adipocyte anabolic and catabolic pathways, the immune-endocrine pattern and the possible repercussion upon adipogenesis. During in vivo infection, both lipolytic and lipogenic pathways are profoundly affected, since the expression of lipolytic enzymes and lipogenic enzymes was intensely downregulated. A similar pattern was observed in isolated adipocytes from infected animals and in 3T3-L1 adipocytes infected in vitro with Trypanosoma cruzi. Moreover, 3T3-L1 adipocytes exposed to plasmas derived from infected animals also tend to downregulate lipolytic enzyme expression which was less evident regarding lipogenic enzymes. Moreover, in vivo-infected adipose tissue reveals a pro-inflammatory profile, with increased leucocyte infiltration accompanied by TNF and IL-6 overexpression, and adiponectin downregulation. Strikingly, the nuclear factor PPAR-γ is strongly decreased in adipocytes during in vivo infection. Attempts to favor PPAR-γ-mediated actions in the adipose tissue of infected animals using agonists failed, indicating that inflammation or parasite-derived factors are strongly involved in PPAR-γ inhibition. Here, we report that experimental acute Trypanosoma cruzi infection disrupts both adipocyte catabolic and anabolic metabolism secondary to PPAR-γ robust downregulation, tipping the balance towards to an adverse status compatible with the adipose tissue atrophy and the acquisition of an inflammatory phenotype.

Alcohol intake aggravates adipose browning and muscle atrophy in cancer-associated cachexia.

Cancer is commonly associated with cachexia, a paraneoplastic syndrome characterized by body weight loss, muscle wasting, adipose tissue atrophy and inflammation. Chronic alcohol consumption increases the risk of multiple types of cancer, and enhances cancer-associated cachexia (CAC), but the underlying mechanisms remain poorly defined. To test, C57BL/6 mice were fed with 0% or 20% (w/v) alcohol for 3 months, then inoculated with B16BL6 melanoma cells subcutaneously in the right side of the hip and continued to feed with/without alcohol for 3 or 4 weeks. Alcohol intake upregulated ALDH1A1 expression and elevated retinoic acid (RA) content in inguinal white adipose tissue (iWAT), which led to enhanced iWAT browning and brown adipose tissue (BAT) activation, accelerating fat loss. Moreover, alcohol increased muscle loss through augmenting muscle protein degradation, cell apoptosis and inflammation. In addition, alcohol reduced satellite cell density and impaired myogenesis in skeletal muscle. Taken together, alcohol aggravates cancer-associated cachexia at least partially through elevating adipose browning and muscle atrophy.

Abstract 5435: Beta-3 adrenergic antagonism can alleviate energy wasting associated with cancer-induced cachexia

Abstract Introduction: Cancer-associated cachexia (CAC) is a wasting syndrome characterized by atrophy of adipose tissue and skeletal muscle as a consequence of cancer. CAC has been shown to be responsible for approximately 20% of cancer deaths alone and reduces tolerance to treatment. The pathological mechanisms underlying this syndrome remains elusive and the treatment options are scarce. One proposed mechanism is the tumor-induced activation of brown adipose tissue (BAT); a thermogenic organ that wastes energy by producing heat via activation of uncoupling protein 1 (UCP1). β3 adrenergic signaling is a strong activator of BAT and the browning of white adipose tissue (WAT). We hypothesized that treatment with a specific β3 antagonist could alleviate CAC. Method: To study cachexia, the LuCAP 32 xenograft model of human prostate cancer was utilized in immunodeficient balb/ca nude mice. After two weeks of tumor growth, treatment with the specific β3 antagonist SR59230A (SR) was started using subcutaneous micro osmotic pumps. Vehicle substance and nontumor bearing (NTB) mice were used as controls. The mice were sacrificed after a treatment period of four weeks and tissues were harvested for subsequent analysis. The PCR analysis was normalized to NTB mice. Results: The mice with tumor started losing weight 20 days after tumor implantation while the nontumor bearing controls gained weight throughout the experiment. The group treated with SR also lost weight but to a significantly lesser degree than vehicle treated animals (-1.7 vs -3.2 g, p=0.032). This was also seen when looking at individual fat depots. Whole body composition, measured by echo MRI, showed that all groups equally lost fat mass over time. However, lean mass in the vehicle group decreased whereas the SR group gained lean mass (-0.41 vs 1.18 g, p=0.036). With respect to total body weight this gain in lean mass was counteracted by the loss of fat mass. PCR analysis of subcutaneous WAT showed a significant decrease in expression of ATGL (2.84 vs 1.98 FC, p=0,006), PPARγ (2.33 vs 1.45 FC, p=0.026) and CD36 (2.11 vs 1.3 FC, p=0.008) for the SR group compared to vehicle, indicating a decreased lipolysis and influx of fatty acids to WAT. The SR treated mice also had a significantly lower expression of UCP1 in WAT compared to controls (2.23 vs 0.58 FC, p=0.023), supporting the notion that the browning of WAT is a driving force for CAC. Conclusion: Our data show that treatment with a specific β3 adrenergic antagonist alleviates CAC through decreased lipolysis of WAT and decreases the expression of markers for WAT browning. This indicates a correlation between decreased browning and severity of CAC. We also provide evidence that β3 antagonism helps preserve muscle mass, which is of major importance for treatment of CAC and something that few other treatment options have been able to show. Citation Format: Fredrick Anderson, Stefan K. Nilsson, Jonas A. Nilsson. Beta-3 adrenergic antagonism can alleviate energy wasting associated with cancer-induced cachexia [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 5435. doi:10.1158/1538-7445.AM2017-5435

Endothelial Foxo1 and Foxo3a Synergistically Repress Skeletal Muscle Vascular Growth and Blood Flow Recovery in a Mouse Model of Hind Limb Ischemia.

Neovascularization in peripheral artery disease (PAD) is impaired despite upregulation of factors that promote blood vessel growth which suggest a concomitant increase of anti‐angiogenic repressors. We previously showed that depletion of FoxO proteins (FoxO1/3a/4) induced angiogenesis and enhanced blood flow recovery in a mouse model of PAD. The purpose of this study is to independently assess the roles of endothelial FoxO1 and synergistic actions of FoxO 1 & 3a in a mouse model of PAD. Mice with tamoxifen‐inducible endothelial specific deletions of FoxO1 (PDGFBCreERT2+;FoxO1L/L, FoxO1Δ) and FoxO1/3a (PDGFBCreERT2+;FoxO1/3aL/L, FoxO1/3Δ), or control (PDGFBCreERT2‐, FoxO1L/L) mice, underwent unilateral ligation of the common femoral artery (at ~8–9 weeks of age) to induce a substantial (~80%) reduction of blood flow in the ligated (LIG) compared to the contralateral (CON) leg. Blood flow recovery was analyzed by laser doppler imaging at baseline, then on days 4, 7, 10 and 14 post‐ligation. Muscle histology was conducted after 14 days. FoxO1/3Δ blood flow (LIG/CON leg perfusion ratio) was recovered to basal levels (1.10 ±0.07; n=6) and significantly greater than FoxO1Δ (0.73 ±0.05; P<0.01, n=5) and FoxO1L/L (0.65 ±0.03; P<0.001, n=5) mice 14 days post‐ligation. Neither FoxO1 nor FoxO1/3 deletion altered capillary density (CD) in the control leg. In contrast, CON leg capillary‐to‐fibre ratio (C: F) in FoxO1/3Δ mice (1.02 ±0.04) was significantly lower than FoxO1L/L (1.48 ±0.08) and FoxO1Δ (1.44 ±0.09) mice (P <0.05). Ischemic muscle was characterized by marked cellular infiltration, deposition of fibrous and adipose tissue and myofibre atrophy. Capillary density was significantly increased in ischemic muscles from FoxO1Δ (CON: 746 ±40.15 vs LIG: 1218 ±187.4 capillaries/mm2; P =0.03) and FoxO1/3aΔ (CON: 743.2 ±39.35 vs LIG: 1661 ±158.5 capillaries/mm2; P =0.005) mice. C: F was increased ~25% in ischemic muscle from FoxO1/3Δ mice (1.28 ±0.05; P <0.05) but was unaltered in FoxO1L/L (1.46 ±0.19) or FoxO1Δ mice (1.55 ±0.22). Our data suggest that the combined effects of FoxO1 & 3a repress vascular growth and blood flow recovery in ischemic muscles more than the independent effects of FoxO1. Funded by CIHR.

Early suppression of adipocyte lipid turnover induces immunometabolic modulation in cancer cachexia syndrome.

Cancer cachexia is a multifactorial syndrome characterized by body weight loss, atrophy of adipose tissue (AT) and systemic inflammation. However, there is limited information regarding the mechanisms of immunometabolic response in AT from cancer cachexia. Male Wistar rats were inoculated with 2 × 107 of Walker 256 tumor cells [tumor bearing (TB) rats]. The mesenteric AT (MeAT) was collected on d 0, 4, 7 (early stage), and 14 (cachexia stage) after tumor cell injection. Surgical biopsies for MeAT were obtained from patients who had gastrointestinal cancer with cachexia. Lipolysis showed an early decrease in glycerol release in TB d 4 (TB4) rats in relation to the control, followed by a 6-fold increase in TB14 rats, whereas de novo lipogenesis was markedly lower in the incorporation of glucose into fatty acids in TB14 rats during the development of cachexia. CD11b and CD68 were positive in TB7 and TB14 rats, respectively. In addition, we found cachexia stage results similar to those of animals in MeAT from patients: an increased presence of CD68+, iNOS2+, TNFα+, and HSL+ cells. In summary, translational analysis of MeAT from patients and an animal model of cancer cachexia enabled us to identify early disruption in Adl turnover and subsequent inflammatory response during the development of cancer cachexia.-Henriques, F. S., Sertié, R. A. L., Franco, F. O., Knobl, P., Neves, R. X., Andreotti, S., Lima, F. B., Guilherme, A., Seelaender, M., Batista, M. L., Jr. Early suppression of adipocyte lipid turnover induces immunometabolic modulation in cancer cachexia syndrome.

Cancer cachexia differentially regulates visceral adipose tissue turnover.

Cancer cachexia (CC) is a progressive metabolic syndrome that is marked by severe body weight loss. Metabolic disarrangement of fat tissues is a very early event in CC, followed by adipose tissue (AT) atrophy and remodelling. However, there is little information regarding the possible involvement of cellular turnover in this process. Thus, in this study, we evaluated the effect of CC on AT turnover and fibrosis of mesenteric (MEAT) and retroperitoneal (RPAT) adipose tissue depots as possible factors that contribute to AT atrophy. CC was induced by a subcutaneous injection of Walker tumour cells (2 × 107) in Wistar rats, and control animals received only saline. The experimental rats were randomly divided into four experimental groups: 0 days, 4 days, 7 days and 14 days after injection. AT turnover was analysed according to the Pref1/Adiponectin ratio of gene expression from the stromal vascular fraction and pro-apoptotic CASPASE3 and CASPASE9 from MEAT and RPAT. Fibrosis was verified according to the total collagen levels and expression of extracellular matrix genes. AT turnover was verified by measurements of lipolytic protein expression. We found that the Pref1/Adiponectin ratio was decreased in RPAT (81.85%, P < 0.05) with no changes in MEAT compared with the respective controls. CASPASE3 and CASPASE9 were activated on day 14 only in RPAT. Collagen was increased on day 7 in RPAT (127%) and MEAT (4.3-fold). The Collagen1A1, Collagen3A1, Mmp2 and Mmp9 mRNA levels were upregulated only in MEAT in CC. Lipid turnover was verified in RPAT and was not modified in CC. We concluded that the results suggest that CC affects RPAT cellular turnover, which may be determinant for RPAT atrophy.

Adipose Tissue-Derived IGFBP1 Facilitates Progression of Leukemia

We recently reported that adipose tissue functions as a reservoir for leukemia stem cells (LSCs) using a murine model of leukemia (Ye et al., Cell Stem Cell, 2016). Intriguingly, the presence of leukemic cells in adipose tissue induces increased lipolysis and the release of free fatty acids (FFA) which in turn fuels the growth of LSCs. Further, adipose tissue protects resident LSCs from chemotherapy. These findings indicate that the unique characteristics of adipose tissue may provide key insights on the growth and survival of leukemic cells. Thus, in the present study we focus on the endocrine function of adipose tissue and explore its role in leukemia development.First, to evaluate secreted factors, we applied adipokine arrays which detect 38 adipokines to leukemia serum collected at different stages of leukemia pathogenesis. Interestingly, we observed a significantly elevated level of serum IGFBP1 as soon as leukemic disease became evident at low levels (~0.5%) in marrow. IGFBP1 increased to levels approximate 200X normal at peak stages of disease burden. ELISA analyses further confirmed these observations.IGFBP1 is normally considered as a liver-derived protein. However, we did not find any changes of IGFBP1 expression in leukemic liver. Rather, we observed a significant increase in the expression of IGFBP1 in adipose tissue. IGFBP1 in conditioned medium (CM) from leukemic gonadal adipose tissue (GAT) is approximate 100X higher than naive GAT. Together, these findings suggest adipose tissue-derived IGFBP1 contributes to the increased serum IGFBP1 we detected in leukemic animals.We next examined the role of IGFBP1 in leukemia development using a neutralizing antibody. Treatment of experimental animals with anti-IGFBP1 antibody significantly decreased leukemic burden in GAT (~40% IgG treated VS. 20% Anti-IGFBP1 treated) while bone marrow (BM) and spleen leukemic engraftment remained unchanged (~40%). Further, less atrophy of adipose tissue as well as less body weight loss was seen in the IGFBP1 neutralizing antibody treated group. Consistent with this observation, serum FFA level was also reduced, suggesting less lipolysis in the IGFBP1 antagonized group. Together, these results indicate that IGFBP1 is involved in the regulation of leukemic cells homing to adipose tissue and consequently leukemia-induced lipolysis.Next we explored the mechanisms for the increased expression of IGFBP1 in adipose tissue. Studies have shown that both FGF21 and hypoxia induce IGFBP1 expression. We did not find any changes of FGF21 expression in adipose tissue or in liver, suggesting FGF21 was not involved in IGFBP1 regulation in our system. In contrast, we observed a five-fold elevation in IGFBP1 mRNA in primary adipose tissue cultured under hypoxic conditions. Studies have shown that both BM and spleen in leukemia mice are already hypoxic in early stages of leukemic development (Benito et al., Plos One, 2011). Thus, we hypothesize that tissue hypoxia may at least partially regulate IGFBP1 in leukemia. Ongoing experiments are testing this hypothesis. Additionally, inflammatory cytokines have been reported to increase IGFBP1 expression. We previously reported significantly increased levels of inflammatory cytokines in the adipose tissue of leukemic mice including TNF-α, IL1 and CSF2 (1.5X normal adipose tissue). Therefore, we hypothesize the local inflammatory cytokine production may also contribute to increased expression of IGFBP1, a theory that is also currently under investigation.IGFBP1 has recently been reported to activate osteoclasts and thus promotes bone metabolism (Wang et al., Cell Metabolism, 2015). Studies have found an increased number of osteoclasts and thus bone loss in our leukemic model (Frisch et al., Blood, 2012). We hypothesize that adipose tissue-derived IGFBP1 contributes to bone loss in leukemic mice. Ongoing experiments are testing whether antagonization of IGFBP1 in leukemic mice will rescue bone loss.Collectively, these findings suggest that adipose tissue-derived IGFBP1 facilitates progression of leukemia through regulation of adipose tissue lipolysis and may promote bone marrow colonization by leukemia cells through activation of osteoclasts. DisclosuresNo relevant conflicts of interest to declare.

426 - Lack of Manganese Superoxide Dismutase Impairs Brown Adipose Tissue Function in Mice

Manganese superoxide dismutase (MnSOD) is an essential member of the cell antioxidant defense system, since it efficiently catalyzes the dismutation of superoxide radical (O2–) to H2O2 and O2 in the mitochondrial matrix. Previous studies from our group have revealed that MnSOD deletion in adipocytes confers resistance to HFD-induced obesity and insulin resistance, due in part to enhanced fatty acid oxidation, mitochondrial respiration and mitochondrial biogenesis in WAT, but resulted in brown adipose tissue (BAT) atrophy and cold intolerance. In order to gain insights into the mechanisms behind BAT atrophy in adipocytes-specific MnSOD knockout mice, we generated mice with BAT-specific deletion of MnSOD using Ucp1-cre line (USod2 KO mice). As expected MnSOD protein was absent from BAT but not from WAT of USod2 KO mice. In addition, a significant decrease in adipogenic markers, such as PPARγ and FABP-4 was observed in BAT of KO mice compared to BAT of control mice. Although no changes were observed in body weight and body composition, USod2 KO mice were cold intolerant, had lower metabolic rate and reduced heat production. Despite lower energy expenditure, USod2 KO mice have improved insulin and glucose tolerance. Taken together, these results indicate that lack of MnSOD in BAT impairs its function.

Dendritic cells maintain dermal adipose-derived stromal cells in skin fibrosis.

Scleroderma is a group of skin-fibrosing diseases for which there are no effective treatments. A feature of the skin fibrosis typical of scleroderma is atrophy of the dermal white adipose tissue (DWAT). Adipose tissue contains adipose-derived mesenchymal stromal cells (ADSCs) that have regenerative and reparative functions; however, whether DWAT atrophy in fibrosis is accompanied by ADSC loss is poorly understood, as are the mechanisms that might maintain ADSC survival in fibrotic skin. Here, we have shown that DWAT ADSC numbers were reduced, likely because of cell death, in 2 murine models of scleroderma skin fibrosis. The remaining ADSCs showed a partial dependence on dendritic cells (DCs) for survival. Lymphotoxin β (LTβ) expression in DCs maintained ADSC survival in fibrotic skin by activating an LTβ receptor/β1 integrin (LTβR/β1 integrin) pathway on ADSCs. Stimulation of LTβR augmented the engraftment of therapeutically injected ADSCs, which was associated with reductions in skin fibrosis and improved skin function. These findings provide insight into the effects of skin fibrosis on DWAT ADSCs, identify a DC-ADSC survival axis in fibrotic skin, and suggest an approach for improving mesenchymal stromal cell therapy in scleroderma and other diseases.

Leukemia Cells Resident in Adipose Tissue Display a Pro-Inflammatory Phenotype and Induce Lipolysis and Atrophy of Adipose Tissue

Aberrant function of adipose tissue (AT) is seen in several diseases including cancer. Studies show that AT facilitates the progression of tumors through paracrine signaling of adipokines as well as regulation of cancer cell metabolism. However, the mechanism by which cancer cells corrupt the normal function of AT to gain proliferative and survival advantages is unknown. Using a murine model of blast crisis CML, we have shown enrichment of phenotypically primitive leukemia cells (Sca+/lin- leukemia cells, termed "PLCs") in the gonadal AT (GAT) as well as a fatty acid oxidation (FAO) regulatory role of AT. In this study, we evaluated the functional alteration of GAT in leukemic mice. We hypothesized that resident leukemia cells change the characteristics of GAT to obtain metabolic benefits.To test this hypothesis, we first examined whether PLCs in GAT differed from PLCs in other tissues including bone marrow, spleen and peripheral blood. To this end, we utilized RNA-seq to obtain a genome-wide transcriptional profile of PLCs in different tissues. We found PLCs in GAT had a distinct gene expression pattern with enrichment of inflammatory response genes. Specifically, pro-inflammatory cytokines and chemokines were highly expressed by PLCs in GAT (Figure 1). Furthermore, the expression of those genes was also increased in the stromal vascular fraction (SVF) of GAT, indicating resident leukemia cells induced inflammation in GAT. Collectively, these results suggest that leukemia cells found in GAT are distinct from leukemia cells in other tissues and may alter the function of GAT.Another characteristic observed in our model was atrophy of GAT (Figure 2) as well as loss of body weight during leukemia progression, indicating the presence of cancer cachexia. Loss of GAT was also found prior to loss of body weight, suggesting the presence of a pre-cachexia stage. We speculated that atrophy of GAT was due to lipolysis induced by inflammation. Indeed, leukemic GAT released more free fatty acid (FFA) and had a lipolytic pattern of adipokines compared to normal GAT. Elevated FFA and lipolytic adipokines were also detected in leukemic serum. Together, these observations demonstrate that GAT in leukemic mice is lipolytic.To gain insights into mechanisms involved in lipolysis of leukemic GAT, we examined expression of lipolysis-related genes (Figure 3). We found that leukemic GAT had increased expression of the adipose triglyceride lipase (Atgl), which is a rate-limiting lipase controlling lipolysis, and reduced expression of lipoprotein lipase (Lpl), whose expression correlates with the influx of fatty acids into adipocytes. Additionally, decreased expression of the cell death activator CIDE-A (Cidea), which is a lipid droplet (LD) associated protein that shields LDs from lipases and inhibits lipolysis, was found in leukemic GAT. Together, these findings suggest that regulation of lipid metabolism is disrupted in leukemic GAT, leading to lipolysis.To test whether resident leukemia cells contribute to the atrophy of GAT, we examined the lipolytic effect of the pro-inflammatory cytokines and chemokines that were highly expressed by PLCs in GAT. We found that IL-1β and CSF2 induced lipolysis and engendered similar gene expression patterns of lipolysis-related genes in 3T3-L1 adipocytes. Notably, palmitate induced the expression of IL-1β in leukemia cells while it had an opposite effect in naive hematopoietic cells, implying a positive feedback loop where inflammation induces lipolysis which induces IL-1β which in turn augments inflammation. Additionally, an increased amount of IL-1β was observed in leukemic serum. Taken together, these data suggest that resident leukemia cells contribute to the atrophy of GAT through paracrine signaling of pro-inflammatory agents. This phenomenon appears to benefit leukemia cells by fostering FAO and metabolic properties that enhance leukemia cell survival.Thus, targeting pathways that mediate inflammation and/or lipolysis may create a microenvironment that is less favorable to leukemia cells. [Display omitted] [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

The role of adipose tissue asymmetric dimethylarginine/dimethylarginine dimethylaminohydrolase pathway in adipose tissue phenotype and metabolic abnormalities in subtotally nephrectomized rats.

The lipodystrophy-like phenotype has been suggested in early chronic kidney disease (CKD). It includes adipose tissue atrophy, systemic insulin resistance (IR), dyslipidemia and ectopic lipid accumulation. To elucidate its pathogenesis, we investigated the role of two uremic toxins that affect insulin sensitivity: an endogenous nitric oxide synthase inhibitor, and asymmetric dimethylarginine (ADMA) and indoxyl sulfate (IS). Six-week-old Sprague-Dawley rats were rendered CKD by subtotal nephrectomy (Nx) and compared with sham-operated rats. Cultured 3T3-L1 fibroblasts were differentiated into mature adipocytes with or without ADMA. Transgenic (Tg) mice overexpressing each isoform of ADMA degrading enzyme, dimethylarginine dimethylaminohydrolase 1 (DDAH1) and DDAH2 were subject to Nx and their phenotypes were investigated. In Nx rats, IR was evident and insulin stimulation failed to activate insulin signaling in adipose tissues. Adipose tissue weight, adipocyte size and adipocyte differentiation marker expressions decreased as a consequence of IR in Nx. Tissue lipid content in the liver and muscle increased in Nx rats. Tissue levels of ADMA, IS and oxidative stress increased in the adipose tissue of Nx rats. Both DDAH1 and DDAH2 expressions decreased, and a putative IS receptor, aryl hydrocarbon receptor, expression increased in the adipose tissue of Nx rats. ADMA inhibited adipocyte differentiation, triglyceride accumulation and insulin signaling, which were reversed by pretreatment with cGMP. In each type of Tg mice overexpressing DDAH1 or DDAH2, all lipodystrophy-like phenotypes induced by Nx were reversed. In mild CKD, dysregulation of the ADMA/DDAH pathway in adipose tissue triggers lipodystrophy-like phenotype changes, including ectopic fat depositions.

The use of anatomically drop-shaped bioactive glass S53P4 implants in the reconstruction of orbital floor fractures—A prospective long-term follow-up study

An isolated fracture of the orbital floor needs reconstruction if there is a clear herniation of adipose tissue or of the rectus inferior muscle into the maxillary sinus. A prospective study was carried out treating 20 patients with an isolated blow-out fracture of the orbital floor or with a combined zygomatico-orbito-maxillary complex fracture, using a newly designed anatomically drop-shaped implants made of bioactive glass (BAG) S53P4. Computed tomography (CT) was performed immediately postoperatively to confirm the correct position of the plate. The patients were followed up for an average of 32 months clinically and radiologically with magnetic resonance imaging (MRI) for an average of 31 months. None of the patients had any signs of complications related to the implant and the clinical outcome was very good. None of the patients had persisting diplopia. The level of the pupillas was normal in 15 of 20 patients. Minor hypo-ophthalmos ranging from 0.5 to 1.0 mm was observed in three patients, and moderate hypo-ophthalmos of 2.0 mm was seen in one patient. Hyperophthalmos of 1.0 mm was seen in one patient. Minor enophthalmos on the operated side ranging from 0.5 to 1.0 mm was seen in eight patients. Mild to moderate paraesthesia of the infraorbital nerve was observed in six patients. The immediate postoperative CT and the long term follow-up MRI revealed that the drop-shaped BAG implants retained their correct position in the orbital floor and did not show any evidence of losing their original shape or material resorption. No adverse tissue reaction was associated with the material. Due to the anatomical drop shape, the implants could successfully maintain the orbital volume and compensate for the retrobulbar adipose tissue atrophy.