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Summary Elevated circulating fatty acids (FAs) contribute to obesity-associated metabolic complications, but the mechanisms by which insulin suppresses lipolysis are poorly understood. We show that α/β-hydrolase domain-containing 15 (ABHD15) is required for the anti-lipolytic action of insulin in white adipose tissue (WAT). Neither insulin nor glucose treatments can suppress FA mobilization in global and conditional Abhd15-knockout (KO) mice. Accordingly, insulin signaling is impaired in Abhd15-KO adipocytes, as indicated by reduced AKT phosphorylation, glucose uptake, and de novo lipogenesis. In vitro data reveal that ABHD15 associates with and stabilizes phosphodiesterase 3B (PDE3B). Accordingly, PDE3B expression is decreased in the WAT of Abhd15-KO mice, mechanistically explaining increased protein kinase A (PKA) activity, hormone-sensitive lipase (HSL) phosphorylation, and undiminished FA release upon insulin signaling. Ultimately, Abhd15-KO mice develop insulin resistance. Notably, ABHD15 expression is decreased in humans with obesity and diabetes compared to humans with obesity and normal glucose tolerance, identifying ABHD15 as a potential therapeutic target to mitigate insulin resistance. [ABSTRACT FROM AUTHOR]

Objective Osteopontin (OPN, Spp1 ) is a protein upregulated in white adipose tissue (WAT) of obese subjects. Deletion of OPN protects mice from high-fat diet-induced WAT inflammation and insulin resistance. However, the alterations mediated by loss of OPN in WAT before the obesogenic challenge have not yet been investigated. Therefore, we hypothesised that the lack of OPN might enhance the pro-adipogenic micro environment before obesity driven inflammation. Methods OPN deficiency was tested in visceral (V) and subcutaneous (SC) WAT from WT and Spp1 −/− female mice. Gene expression for hypoxia, inflammation and adipogenesis was checked in WT vs. Spp1 −/− mice (n = 15). Adipocytes progenitor cells (APC) were isolated by fluorescence cell sorting and role of OPN deficiency in adipogenesis was investigated by cell images and RT-PCR. Results We show that Spp1 −/− maintained normal body and fat-pad weights, although hypoxia and inflammation markers were significantly reduced. In contrast, expression of genes involved in adipogenesis was increased in WAT from Spp1 −/− mice. Strikingly, APC from Spp1 −/− were diminished but differentiated more efficiently to adipocytes than those from control mice. Conclusions APC from SC-WAT of lean OPN-deficient mice display an enhanced capacity for differentiating to adipocytes. These alterations may explain the healthy expansion of WAT in the OPN-deficient model which is associated with reduced inflammation and insulin resistance. [ABSTRACT FROM AUTHOR]

Objective Recent findings point towards an important role of local macrophage proliferation also in obesity-induced adipose tissue inflammation that underlies insulin resistance and type 2 diabetes. Osteopontin (OPN) is an inflammatory cytokine highly upregulated in adipose tissue (AT) of obese and has repeatedly been shown to be functionally involved in adipose-tissue inflammation and metabolic sequelae. In the present work, we aimed at unveiling both the role of OPN in human monocyte and macrophage proliferation as well as the impact of OPN deficiency on local macrophage proliferation in a mouse model for diet-induced obesity. Methods The impact of recombinant OPN on viability, apoptosis, and proliferation was analyzed in human peripheral blood monocytes and derived macrophages. Wild type (WT) and OPN knockout mice (SPP1KO) were compared with respect to in vivo adipose tissue macrophage and in vitro bone marrow-derived macrophage (BMDM) proliferation. Results OPN not only enhanced survival and decreased apoptosis of human monocytes but also induced proliferation similar to macrophage colony stimulating factor (M-CSF). Even in fully differentiated monocyte-derived macrophages, OPN induced a proliferative response. Moreover, proliferation of adipose tissue macrophages in obese mice was detectable in WT but virtually absent in SPP1KO. In BMDM, OPN also induced proliferation while OPN as well as M-CSF-induced proliferation was similar in WT and SPP1KO. Conclusions These data confirm that monocytes and macrophages not only are responsive to OPN and migrate to sites of inflammation but also they survive and proliferate more in the presence of OPN, a mechanism also strongly confirmed in vivo . Therefore, secreted OPN appears to be an essential player in AT inflammation, not only by driving monocyte chemotaxis and macrophage differentiation but also by facilitating local proliferation of macrophages. [ABSTRACT FROM AUTHOR]

Summary: Increased visceral fat is associated with a high risk of diabetes and metabolic syndrome and is in part caused by excessive glucocorticoids (GCs). However, the molecular mechanisms remain undefined. We now identify the GC-dependent gene LIM domain only 3 (LMO3) as being selectively upregulated in a depot-specific manner in human obese visceral adipose tissue, localizing primarily in the adipocyte fraction. Visceral LMO3 levels were tightly correlated with expression of 11β-hydroxysteroid dehydrogenase type-1 (HSD11B1), the enzyme responsible for local activation of GCs. In early human adipose stromal cell differentiation, GCs induced LMO3 via the GC receptor and a positive feedback mechanism involving 11βHSD1. No such induction was observed in murine adipogenesis. LMO3 overexpression promoted, while silencing of LMO3 suppressed, adipogenesis via regulation of the proadipogenic PPARγ axis. These results establish LMO3 as a regulator of human adipogenesis and could contribute a mechanism resulting in visceral-fat accumulation in obesity due to excess glucocorticoids. [Copyright &y& Elsevier]

Summary: Lipid mobilization (lipolysis) in white adipose tissue (WAT) critically controls lipid turnover and adiposity in humans. While the acute regulation of lipolysis has been studied in detail, the transcriptional determinants of WAT lipolytic activity remain still largely unexplored. Here we show that the genetic inactivation of transcriptional cofactor transducin beta-like-related 1(TBLR1) blunts the lipolytic response of white adipocytes through the impairment of cAMP-dependent signal transduction. Indeed, mice lacking TBLR1 in adipocytes are defective in fasting-induced lipid mobilization and, when placed on a high-fat-diet, show aggravated adiposity, glucose intolerance, and insulin resistance. TBLR1 levels are found to increase under lipolytic conditions in WAT of both human patients and mice, correlating with serum free fatty acids (FFAs). As a critical regulator of WAT cAMP signaling and lipid mobilization, proper activity of TBLR1 in adipocytes might thus represent a critical molecular checkpoint for the prevention of metabolic dysfunction in subjects with obesity-related disorders. [ABSTRACT FROM AUTHOR]

Background: Chronic adipose tissue inflammation is a hallmark of obesity, triggering the development of associated pathologies, particularly type 2 diabetes. Long-chain n-3 PUFAs reduce cardiovascular events and exert well-established antiinflammatory effects, but their effects on human adipose tissue inflammation are unknown. Objective: We investigated whether n-3 PUFAs reduce adipose tissue inflammation in severely obese nondiabetic patients. Design: We treated 55 severely obese nondiabetic patients, scheduled to undergo elective bariatric surgery, with 3.36 g long-chain n-3 PUFAs/d (EPA, DHA) or an equivalent amount of butterfat as control, for 8 wk, in a randomized open-label controlled clinical trial. The primary efficacy measure was inflammatory gene expression in visceral and subcutaneous adipose tissue samples (subcutaneous adipose tissue and visceral adipose tissue), collected during surgery after the intervention. Secondary efficacy variables were adipose tissue production of antiinflammatory n-3 PUFA-derived eicosanoids, plasma concentrations of inflammatory markers, metabolic control, and the effect of the Pro 12Ala PPARG polymorphism on the treatment response. Results: Treatment with n-3 PUFAs, which was well tolerated, decreased the gene expression of most analyzed inflammatory genes in subcutaneous adipose tissue (P < 0.05) and increased production of antiinflammatory eicosanoids in visceral adipose tissue and subcutaneous adipose tissue (P < 0.05). In comparison with control subjects who received butterfat, circulating interleukin-6 and triglyceride concentrations decreased significantly in the n-3 PUFA group (P = 0.04 and P = 0.03, respectively). The Pro12Ala polymorphism affected the serum cholesterol response to n-3 PUFA treatment. Conclusions: Treatment with long-chain n-3 PUFAs favorably modulated adipose tissue and systemic inflammation in severely obese nondiabetic patients and improved lipid metabolism. These effects may be beneficial in the long-term treatment of obesity. This trial was registered at clinicaltrials.gov as NCT00760760. [ABSTRACT FROM AUTHOR]

Abstract: Although obesity traditionally has been considered a condition of low risk for osteoporosis, this classic view has recently been questioned. The aim of this study was to assess bone microarchitecture and turnover in a mouse model of high-fat diet–induced obesity. Seven-week-old male C57BL/6J mice (n = 18) were randomized into 3 diet groups. One third (n = 6) received a low-fat diet for 24 weeks, one third was kept on an extended high-fat diet (eHF), and the remaining was switched from low-fat to high-fat chow 3 weeks before sacrifice (sHF). Serum levels of insulin, leptin, adiponectin, osteocalcin, and cross-linked telopeptides of type I collagen (CTX) were measured. In addition, bone microarchitecture was analyzed by micro–computed tomography; and lumbar spine bone density was assessed by dual-energy x-ray absorptiometry. The CTX, body weight, insulin, and leptin were significantly elevated in obese animals (sHF: +48%, +24%, +265%, and +102%; eHF: +43%, +52%, +761%, and +292%). The CTX, body weight, insulin, and leptin showed a negative correlation with bone density and bone volume. Interestingly, short-term high-fat chow caused similar bone loss as extended high-fat feeding. Bone volume was decreased by 12% in sHF and 19% in eHF. Bone mineral density was 25% (sHF) and 27% (eHF) lower when compared with control mice on low-fat diet. As assessed by the structure model index, bone microarchitecture changed from plate- to rod-like appearance upon high-fat challenge. Trabecular and cortical thickness remained unaffected. Short-term and extended high-fat diet–induced obesity caused significant bone loss in male C57BL/6J mice mainly because of resorptive changes in trabecular architecture. [ABSTRACT FROM AUTHOR]

Abstract: It is now broadly accepted that low-grade chronic inflammation associated with obesity leads to the onset of insulin resistance and type 2 diabetes mellitus. Obesity-associated inflammation is characterized by an increased abundance of macrophages in adipose tissue along with production of inflammatory cytokines. Adipose tissue macrophages (ATMs) are suspected to be the major source of inflammatory mediators such as TNF-α and IL-6 that interfere with adipocyte function by inhibiting insulin action. However, ATMs phenotypically resemble alternatively activated (M2) macrophages and are capable of anti-inflammatory mediator production challenging the concept that ATMs are simply the “bad guys” in obese adipose tissue. Triggers promoting ATM recruitment, ATM functions and dysfunctions, and stimuli and molecular mechanisms that drive them into becoming detrimental to their environment are subject to current research. Strategies to interfere with ATM recruitment and adverse activation could give rise to novel options for treatment and prevention of insulin resistance and type 2 diabetes mellitus. [Copyright &y& Elsevier]

Abstract: The model of membrane compartmentalization by self-organizing functional lipid microdomains, named lipid rafts, has been a fruitful concept resulting in great progress in understanding T cell signal transduction. However, due to recent results it has become clear that lipid rafts describe only one out of several membrane organizing principles crucial for T cell activation besides fences and pickets and protein–protein interactions that take part in the formation of the immunological synapse as a highly organized structure at the T cell contact site to the antigen-presenting cell. This review describes the concepts of lipid rafts and other membrane organizing principles to evolve a novel integrated model on the functional role of microdomains in immunological synapse formation and T cell activation. Further research has to elucidate the relative contribution and interrelation of different modes of membrane organization in productive T cell activation. [Copyright &y& Elsevier]

Osteopontin (OPN) is a multifunctional protein involved in several inflammatory processes and pathogeneses including obesity-related disorders and cancer. OPN binds to a variety of integrin receptors and CD44 resulting in a proinflammatory stimulus. Therefore, OPN constitutes a novel interesting target to develop new therapeutic strategies, which counteract OPN's proinflammatory properties. We established a humanized SPP1 (hSPP1) mouse model and evaluated its suitability as a model for obesity and insulin resistance. Unchallenged hSPP1 animals did not significantly differ in body weight and gross behavioral properties compared to wild-type (WT) animals. High-fat diet-challenged hSPP1 similarly developed obesity and inflammation, whereas insulin resistance was markedly changed. However, OPN expression profile in tissues was significantly altered in hSPP1 compared to WT depending on the diet. In conclusion, we developed a versatile humanized model to study the action of OPN in vivo and to develop strategies that target human OPN in a variety of pathologies. [ABSTRACT FROM AUTHOR]

Summary: Background: Adipose-derived stem cells (ASCs) play a key role in tissue engineering approaches and are probably of major importance in the context of autologous fat transfer. A number of different tools for harvesting ASCs-containing fat tissue have been established. Such devices should be easy to handle, time saving, low priced, safe and provide a high amount of viable ASCs in the aspirate. Power-assisted liposuction (PAL) has not yet been described in the literature as a tool for fat harvesting for lipotranfer. Aim of this study was to investigate ASCs' viability in fat tissue harvested using PAL versus manual aspiration (MA). Methods: Fat tissue was obtained from 9 donors undergoing abdominoplasty. Samples were divided into two sections. Out of each section fat was harvested using either PAL or MA. Number of isolated ASCs was defined, proliferation rate was determined and cell viability was assessed by flow cytometry. The ability of isolated ASCs to differentiate into mature adipocytes was analyzed by gene marker expression. Results: The number of viable ASCs and the proliferation rates did not significantly differ between PAL and MA but cells harvested using PAL showed significantly higher expression levels of differentiation markers adiponectin, GLUT4 and PPARg. Conclusion: Our results show that PAL is a feasible method for harvesting fat tissue containing viable ASCs. Quantity and quality of PAL-harvested ASC is similar or even better, respectively, compared to ASCs harvested by MA. [Copyright &y& Elsevier]

Abstract: Objectives: We analysed the long-term clinical and radiological results of 68 consecutive total knee replacements in 50 patients with rheumatoid arthritis. Methods: At a mean follow-up of 11.2±1.2 years (range, 9.7–13.7) all revisions were included. Thirty-seven knees in 28 patients still alive were followed retrospectively clinically and radiologically, all other patients who died without revision were censored at time of the last clinical follow-up and no patient was lost to follow-up. Revision was necessary in 13 knees (19%, one revised twice), including an overall deep infection rate of 1.47%. Results: The survival rate was 81.6±0.05% at 12 years with any revision or removal of the prosthesis as an end point. There was no significant difference in survival between cemented, uncemented or hybrid fixation (log rank, 0.2544). The average Knee Society Scores were 77.2 points clinical (range, 40–95 points) and 75.3 points functional (range, 30–100 points), respectively, at final follow-up. The body mass index (BMI) was 25.9 at surgery and 25.3 at follow-up (n.s.). There was no correlation between BMI, age, side, gender and revision frequency. No arthroplasty was at risk for removal or revision at follow-up. Conclusions: The study shows good 10–12-year clinical and radiological results for the PCA knee replacement in patients with rheumatoid arthritis without preference for the method of fixation or patient weight. [Copyright &y& Elsevier]

Résumé: Objectifs: Nous avons analysé l’évolution clinique et radiologique à long terme de 68 prothèses totales du genou consécutives chez 50 patients atteints de polyarthrite rhumatoïde. Méthodes: Au cours d’un suivi dont la durée moyenne était de 11,2±1,2 ans (éventail entre 9,7 et 13,7 ans) toutes les révisions (reprises) de prothèses ont été incluses. L’évolution clinique et radiologique a été suivie rétrospectivement pour 37 genoux chez 28 patients encore en vie. Tous les autres patients qui sont décédés sans révision ont été pris en compte au moment du dernier contrôle de suivi et aucun patient n’a été perdu au cours du suivi. Une révision s’est imposée pour 13 genoux (19 %, un révisé deux fois), avec un taux global d’infection profonde de 1,47 %. Résultats: Le taux de survie était de 81,6±0,05 à 12 ans en considérant toute révision ou extraction de la prothèse comme point final. Aucune différence significative n’a été observée entre les fixations avec ou sans ciment ou celles hybrides (Log rank 0,2544). Le score moyen IKS de la Knee Society était respectivement de 77,2 points cliniques (éventail de 40 à 95 points) et 75,3 points fonctionnels (éventail de 30 à 100 points) au contrôle final. L’indice de masse corporelle (IMC) était 25,9 au moment de la chirurgie et 25,3 au suivi (n.s.). Il n’y avait aucune corrélation entre l’IMC, l’âge, le côté, le sexe et la fréquence de révision. Aucune arthroplastie n’était à risque de retrait ou de révision au suivi. Conclusions: L’étude montre dix à 12 années de résultats cliniques et radiologiques pour la prothèse du genou PCA chez des patients atteints de polyarthrite rhumatoïde sans préférence pour la méthode de fixation ou le poids du patient. [Copyright &y& Elsevier]

Obesity causes insulin resistance via a chronic low-grade inflammation. This inflammation is characterized by elevated pro-inflammatory markers and macrophage accumulation in the adipose tissue (AT). AT inflammation is a key factor causing insulin resistance and thus type 2 diabetes, both linked to atherosclerotic cardiovascular disease. Osteopontin (OPN), a well-known inflammatory cytokine, is involved in obesity-linked complications including AT inflammation, insulin resistance, atherosclerosis and CVD. During inflammation, OPN is proteolytically cleaved by matrix metalloproteinases or thrombin leading to increased OPN activity. Therefore, OPN provides a new interesting target for immunological prevention and treatment of obesity-associated diseases. The aim of our study was to evaluate peptide-based vaccines against integrin binding sites of OPN and to examine whether these active immunotherapies are functional in reducing metabolic tissue inflammation, insulin resistance, and atherosclerosis in a cardio-metabolic (Ldlr −/− mice) and a diet-induced obesity model (WT mice). However, atherosclerosis, insulin resistance and AT inflammation were not diminished after treatment with OPN-derived peptides in murine models. Lack of efficacy was based on a failure to induce antibodies capable to bind epitopes in the context of functional OPN protein. In conclusion, our data point to unexpected challenges in the immunotherapeutic targeting of adhesive motives, such as RGD containing sequences, on endogenous proteins. [ABSTRACT FROM AUTHOR]

Polyunsaturated fatty acids (PUFAs) modulate immune responses leading to clinically significant benefi. cial effects in a variety of inflammatory disorders. PUFA effects on T cells have been extensively studied, but their influence on human dendritic cells (DCs), which are the most potent antigen-presenting cells and play a key role in initiating immune responses, has not been elucidated so far. Here we show that PUFAs of the n-3 and n-6 series (arachidonic and eicosapentaenoic acid) affect human monocyte-derived DC differentiation and inhibit their activation by LPS, resulting in altered DC surface molecule expression and diminished cytokine secretion. Furthermore, the potency to stimulate T cells was markedly inhibited in PUFA-treated DCs. The PUFA-mediated block in LPS-induced DC activation is reflected by diminished TNF-α, IL-12p40, CD40, and COX-2 mRNA levels. Strikingly, typical LPS-induced signaling events such as degradation of Ir, B and activation of NF-κB were not affected by PUFAs, even though DC membrane lipid composition was markedly altered. Arachidonic and eicosapentaenoic acid both altered DC prostaglandin production, but inhibitors of cyclooxygenases and lipoxygenases did not abolish PUFA effects, indicating that the observed PUFA actions on DCs were independent of autoregulation via eicosanoids. These data demonstrate a unique interference with DC activation and function that could significantly contribute to the well known anti-inflammatory effects of PUFAs. [ABSTRACT FROM AUTHOR]

The obesity epidemic in industrialized countries is associated with increases in cardiovascular disease (CVD) and certain types of cancer. In animal models, caloric restriction (CR) suppresses these diseases as well as chemical-induced tissue damage. These beneficial effects of CR overlap with those altered by agonists of nuclear receptors (NR) under control of the fasting-responsive transcriptional co-activator, peroxisome proliferator-activated co-activator 1α (PGC-1α). In a screen for compounds that mimic CR effects in the liver, we found statistically significant overlaps between the CR transcript profile in wild-type mice and the profiles altered by agonists of lipid-activated NR, including peroxisome proliferator-activated receptor α (PPARα), liver X receptor, and their obligate heterodimer partner, retinoid X receptor. The overlapping genes included those involved in CVD (lipid metabolism and inflammation) and cancer (cell fate). Based on this overlap, we hypothesized that some effects of CR are mediated by PPARα. As determined by transcript profiling, 19% of all gene expression changes in wild-type mice were dependent on PPARα, including Cyp4a10 and Cyp4a14, involved in fatty acid ω-oxidation, acute phase response genes, and epidermal growth factor receptor but not increases in PGC-1α. CR protected the livers of wild-type mice from damage induced by thioacetamide, a liver toxicant and hepatocarcinogen. CR protection was lost in PPARα-null mice due to inadequate tissue repair. These results demonstrate that PPARα mediates some of the effects of CR and indicate that a pharmacological approach to mimicking many of the beneficial effects of CR may be possible. [ABSTRACT FROM AUTHOR]

Deficiency of SAP (SLAM (signaling lymphocyte activation molecule)-associated protein) protein is associated with a severe immunodeficiency, the X-linked lymphoproliferative disease (XLP) characterized by an inappropriate immune reaction against Epstein-Barr virus infection often resulting in a fatal clinical course. Several studies demonstrated altered NK and T cell function in XLP patients; however, the mechanisms underlying XLP disease are still largely unknown. Here, we show that non-transformed T cell lines obtained from XLP patients were defective in several activation events such as IL-2 production, CD25 expression, and homotypic cell aggregation when cells were stimulated via T cell antigen receptor (TCR)·CD3 but not when early TCRdependent events were bypassed by stimulation with phorbol 12-myristate 13-acetate/ionomycin. Analysis of proximal T cell signaling revealed imbalanced TCR·CD3induced signaling in SAP-deficient T cells. Although phospholipase Cγ1 phosphorylation and calcium response were both enhanced in T cells from XLP patients, phosphorylation of VAV and downstream signal transduction events such as mitogen-activated protein kinase phosphorylation and IL-2 production were diminished. Importantly, reconstitution of SAP expression by retroviral-mediated gene transfer completely restored abnormal signaling events in T cell lines derived from XLP patients. In conclusion, SAP mutation or deletion in XLP patients causes profound defects in T cell activation, resulting in immune deficiency. Moreover, these data provide evidence that SAP functions as an essential integrator in early TCR signal transduction. [ABSTRACT FROM AUTHOR]