Senescence-associated ß-galactosidase in subcutaneous adipose tissue associates with altered glycaemic status and truncal fat in severe obesity.

AIM/HYPOTHESIS: Altered adipose tissue secretory profile contributes to insulin resistance and type 2 diabetes in obesity. Preclinical studies have identified senescent cells as a cellular source of proinflammatory factors in adipose tissue of obese mice. In humans, potential links with obesity comorbidities are poorly defined. Here, we investigated adipose tissue senescent status and relationships with metabolic complications in human obesity. METHODS: The study includes a prospective cohort of 227 individuals with severe obesity. A photometric method was used to quantify senescence-associated ß-galactosidase (SA-ß-gal) activity in paired subcutaneous and omental adipose tissue biopsies obtained during gastric surgery. Gene and secretory profiling was performed in adipose tissue biopsies and in human primary pre-adipocytes in the presence or absence of senolytic drugs targeting senescent cells. Participants were phenotyped for anthropometric and bioclinical variables, metabolic complications and gastric surgery-induced improvement to address relationships with adipose tissue SA-ß-gal. RESULTS: SA-ß-gal activity was sevenfold higher in subcutaneous than in omental adipose tissue and not associated with BMI or chronological age. Several factors, including insulin-like growth factor binding protein 3 (IGFBP3), plasminogen activator inhibitor 1 (PAI1), C-C motif chemokine ligand 2 (CCL2) and IL-6, were upregulated in subcutaneous adipose tissue in relation with SA-ß-gal (p for linear trend across tertiles <0.05) and in pre-adipocytes cultured with inflammatory macrophage conditioned media. Senolytic treatment reduced SA-ß-gal staining and normalised these alterations. In the whole population, subcutaneous adipose tissue SA-ß-gal activity was positively associated with serum leptin, markers of insulin resistance and increased trunk fat mass. Metabolic complications, including type 2 diabetes and dyslipidaemia, were more prevalent in patients with high levels of SA-ß-gal, but improved with bariatric surgery whatever the initial adipose tissue senescent status. CONCLUSIONS/INTERPRETATION: This study highlights a phenotype of senescence in adipose tissue of severely obese individuals, which characterises prominently subcutaneous fat depots. Subcutaneous adipose tissue senescence is significantly linked to altered glucose metabolism and body fat distribution. Elimination of senescent cells through senolytic treatment could alleviate metabolic complications in severely obese people. Graphical abstract.

Comparative Evaluation of Microbiota Engraftment Following Fecal Microbiota Transfer in Mice Models: Age, Kinetic and Microbial Status Matter.

The intestinal microbiota and its functions are intricately interwoven with host physiology. Colonizing rodents with donor microbiota provides insights into host-microbiota interactions characterization and the understanding of disease physiopathology. However, a better assessment of inoculation methods and recipient mouse models is needed. Here, we compare the engraftment at short and long term of genetically obese mice microbiota in germ-free (GF) mice and juvenile and adult specific pathogen free (SPF) mice. We also tested the effects of initial microbiota depletion before microbiota transfer. In the present work, donor microbiota engraftment was better in juvenile SPF mice than in adult SPF mice. In juvenile mice, initial microbiota depletion using laxatives or antibiotics improved donor microbiota engraftment 9 weeks but not 3 weeks after microbiota transfer. Microbiota-depleted juvenile mice performed better than GF mice 3 weeks after the microbiota transfer. However, 9 weeks after transfer, colonized GF mice microbiota had the lowest Unifrac distance to the donor microbiota. Colonized GF mice were also characterized by a chronic alteration in intestinal absorptive function. With these collective results, we show that the use of juvenile mice subjected to initial microbiota depletion constitutes a valid alternative to GF mice in microbiota transfer studies.

Immune cell-derived cytokines contribute to obesity-related inflammation, fibrogenesis and metabolic deregulation in human adipose tissue.

Adipose tissue contains a variety of immune cells, which vary in abundance and phenotype with obesity. The contribution of immune cell-derived factors to inflammatory, fibrotic and metabolic alterations in adipose tissue is not well established in human obesity. Human primary adipose tissue cells, including pre-adipocytes, endothelial cells and mature adipocytes, were used to investigate deregulation of cell- and pathway-specific gene profiles. Among factors known to alter adipose tissue biology, we focus on inflammatory (IL-1ß and IL-17) and pro-fibrotic (TGF-ß1) factors. rIL-1ß and rIL-17 induced concordant pro-inflammatory transcriptional programs in pre-adipocytes and endothelial cells, with a markedly more potent effect of IL-1ß than IL-17. None of these cytokines had significant effect on fibrogenesis-related gene expression, contrasting with rTGF-ß1-induced up-regulation of extracellular matrix components and pro-fibrotic factors. In mature adipocytes, all three factors promoted down-regulation of genes functionally involved in lipid storage and release. IL-1ß and IL-17 impacted adipocyte metabolic genes in relation with their respective pro-inflammatory capacity, while the effect of TGF-ß1 occurred in face of an anti-inflammatory signature. These data revealed that IL-1ß and IL-17 had virtually no effect on pro-fibrotic alterations but promote inflammation and metabolic dysfunction in human adipose tissue, with a prominent role for IL-1ß.

Chronic Exposure to Low Doses of Dioxin Promotes Liver Fibrosis Development in the C57BL/6J Diet-Induced Obesity Mouse Model.

BACKGROUND: Exposure to persistent organic pollutants (POPs) has been associated with the progression of chronic liver diseases, yet the contribution of POPs to the development of fibrosis in non-alcoholic fatty liver disease (NAFLD), a condition closely linked to obesity, remains poorly documented. OBJECTIVES: We investigated the effects of subchronic exposure to low doses of the POP 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), an aryl hydrocarbon receptor ligand, on NAFLD progression in diet-induced obese C57BL/6J mice. METHODS: Male C57BL/6J mice were fed either a 10% low-fat (LFD) or a 45% high-fat (HFD) purified diet for 14 weeks and TCDD-exposed groups were injected once a week with 5 µg/kg TCDD or the vehicle for the last 6 weeks of the diet. RESULTS: Liver histology and triglyceride levels showed that exposure of HFD fed mice to TCDD worsened hepatic steatosis, as compared to either HFD alone or LFD plus TCDD and the mRNA levels of key genes of hepatic lipid metabolism were strongly altered in co-treated mice. Further, increased liver collagen staining and serum transaminase levels showed that TCDD induced liver fibrosis in the HFD fed mice. TCDD in LFD fed mice increased the expression of several inflammation and fibrosis marker genes with no additional effect from a HFD. CONCLUSIONS: Exposure to TCDD amplifies the impairment of liver functions observed in mice fed an enriched fat diet as compared to a low fat diet. The results provide new evidence that environmental pollutants promote the development of liver fibrosis in obesity-related NAFLD in C57BL/6J mice. Citation: Duval C, Teixeira-Clerc F, Leblanc AF, Touch S, Emond C, Guerre-Millo M, Lotersztajn S, Barouki R, Aggerbeck M, Coumoul X. 2017. Chronic exposure to low doses of dioxin promotes liver fibrosis development in the C57BL/6J diet-induced obesity mouse model. Environ Health Perspect 125:428-436; http://dx.doi.org/10.1289/EHP316.

Adipose tissue adaptive response to trans-10,cis-12-conjugated linoleic acid engages alternatively activated M2 macrophages.

In mice, nutritional supplementation with the trans-10,cis-12 isomer of linoleic acid (t10,c12-CLA) promotes lipoatrophy, hyperinsulinemia, and macrophage infiltration in white adipose tissue (WAT). We explored the dynamics of these interrelated responses over 2 consecutive 7 d periods of t10,c12-CLA administration and withdrawal. t10,c12-CLA down-regulated lipogenic and lipolytic gene expression and increased collagen deposition, but with no evidence of cross-linking. An abundant CD45(+) cell infiltrate, comprising prominently CD206(+)CD11c(-) macrophages, was found in WAT in association with an anti-inflammatory gene signature. Infiltration of natural killer (NK) and dendritic cells contributed to WAT's innate immune response to t10,c12-CLA. Less abundant adaptive immune cells colonized WAT, including B, NK T, γδ T, and αß T cells. By contrast, T-regulatory cell abundance was not affected. Interruption of treatment allowed recovery of WAT mass and normalization of insulinemia, coincident with regain of WAT homeostasis owing to a coordinated reversion of genic, structural, and immune deregulations. These data revealed a striking resilience of WAT after a short-term metabolic injury induced by t10,c12-CLA, which relies on alternatively activated M2 macrophage engagement. In addition, the temporal links between variations in WAT alterations and insulinemia upon t10,c12-CLA manipulation strengthen the view that WAT dysfunctional status is critically involved in altered glucose homeostasis.

Cathepsin S inhibition lowers blood glucose levels in mice.

AIMS/HYPOTHESIS: Cathepsin S (CatS) belongs to a family of proteases that have been implicated in several disease processes. We previously identified CatS as a protein that is markedly overexpressed in adipose tissue of obese individuals and downregulated after weight loss and amelioration of glycaemic status induced by gastric bypass surgery. This prompted us to test whether the protease contributes to the pathogenesis of type 2 diabetes using mouse models with CatS inactivation. METHODS: CatS knockout mice and wild-type mice treated with orally active small-molecule CatS inhibitors were fed chow or high-fat diets and explored for change in glycaemic status. RESULTS: CatS deletion induced a robust reduction in blood glucose, which was preserved in diet-induced obesity and with ageing and was recapitulated with CatS inhibition in obese mice. In vivo testing of glucose tolerance, insulin sensitivity and glycaemic response to gluconeogenic substrates revealed that CatS suppression reduced hepatic glucose production despite there being no improvement in insulin sensitivity. This phenotype relied on downregulation of gluconeogenic gene expression in liver and a lower rate of hepatocellular respiration. Mechanistically, we found that the protein 'regulated in development and DNA damage response 1' (REDD1), a factor potentially implicated in reduction of respiratory chain activity, was overexpressed in the liver of mice with CatS deficiency. CONCLUSIONS/INTERPRETATION: Our results revealed an unexpected metabolic effect of CatS in promoting pro-diabetic alterations in the liver. CatS inhibitors currently proposed for treatment of autoimmune diseases could help to lower hepatic glucose output in obese individuals at risk for type 2 diabetes.

T cell-derived IL-22 amplifies IL-1ß-driven inflammation in human adipose tissue: relevance to obesity and type 2 diabetes.

Proinflammatory cytokines are critically involved in the alteration of adipose tissue biology leading to deterioration of glucose homeostasis in obesity. Here we show a pronounced proinflammatory signature of adipose tissue macrophages in type 2 diabetic obese patients, mainly driven by increased NLRP3-dependent interleukin (IL)-1ß production. IL-1ß release increased with glycemic deterioration and decreased after gastric bypass surgery. A specific enrichment of IL-17- and IL-22-producing CD4(+) T cells was found in adipose tissue of type 2 diabetic obese patients. Coculture experiments identified the effect of macrophage-derived IL-1ß to promote IL-22 and IL-17 production by human adipose tissue CD4(+) T cells. Reciprocally, adipose tissue macrophages express IL-17 and IL-22 receptors, making them sensitive to IL-17 and IL-22. IL-22 increased IL-1ß release by inducing pro-IL-1ß transcription through activation of C-Jun pathways in macrophages. In sum, these human data identified IL-1ß and the T-cell cytokine IL-22 as key players of a paracrine inflammatory pathway previously unidentified in adipose tissue, with a pathological relevance to obesity-induced type 2 diabetes. These results provide an additional rationale for targeting IL-1ß in obesity-linked type 2 diabetes and may have important implications for the conception of novel combined anti-IL-1ß and anti-IL-22 immunotherapy in human obesity.

Intima-media thickness in severe obesity: links with BMI and metabolic status but not with systemic or adipose tissue inflammation.

OBJECTIVE: Obesity is associated with cardiovascular risk and a low-grade inflammatory state in both blood and adipose tissue (AT). Whether inflammation contributes to vascular alteration remains an open question. To test this hypothesis, we measured arterial intima-media thickness (IMT), which reflects subclinical atherosclerosis, in severely obese subjects and explored associations with systemic inflammation and AT inflammation. RESEARCH DESIGN AND METHODS: IMT of the carotid artery (C-IMT) and IMT of the femoral artery (F-IMT) were measured in 132 nonobese (control) subjects (BMI 22.3 kg/m2; mean age 44.8 years) and 232 subjects who were severely obese without diabetes (OB/ND; n = 146; BMI 48.3 kg/m2; age 38.2 years) or severely obese with type 2 diabetes (OB/D; n = 86; BMI 47.0; age 49.4 years). In 57 OB/ND subjects, circulating soluble E-selectin, matrix metalloproteinase 9, myeloperoxidase, soluble intracellular adhesion molecule 1, soluble vascular cell adhesion molecule 1, tissue plasminogen activator inhibitor 1, cystatin C, cathepsin S, and soluble CD14 were measured in serum. AT macrophages were quantified by CD68 immunochemistry. RESULTS: Both C-IMT and F-IMT increased in OB/ND and OB/D patients. In OB/ND patients, age was the sole independent determinant of IMT. No significant association was found with circulating inflammation-related molecules, number of CD68+ cells, or the presence of crown-like structures in visceral or subcutaneous AT of OB/ND patients. CONCLUSIONS: IMT increased with severe obesity but was not influenced by the degree of systemic inflammation or AT macrophage accumulation.

Mast cells in human adipose tissue: link with morbid obesity, inflammatory status, and diabetes.

AIMS AND HYPOTHESIS: Mast cells are immune cells known for their role in several inflammatory and fibrotic diseases. Recent works in mice suggest that mast cells could be cellular actors involved in the pathophysiology of obesity, a disease characterized by white adipose tissue (WAT) and systemic inflammation. The aim of the study was to better characterize mast cells in WAT of obese with or without type 2 diabetes and lean subjects as well as to explore the relationship with WAT inflammation and fibrosis. METHODS: Subcutaneous and omental adipose tissue from six lean subjects, 10 obese nondiabetic, and 10 diabetic patients was analyzed by immunohistochemistry and real-time PCR for inflammatory and fibrosis markers. Cytokines secretion of mast cells isolated from WAT and cultured in different conditions was estimated by cytokine array kit. RESULTS: We found that mast cells are activated in human adipose tissue and localized preferentially in fibrosis depots, a local condition that stimulates their inflammatory state. Mast cells with tryptase(+) chymase(+) staining tended to be higher in obese omental adipose tissue. We found positive links between mast cell number and several characteristics of obese WAT including fibrosis, macrophage accumulation, and endothelial cell inflammation. Mast cell number and their inflammatory phenotype are associated with diabetes parameters. CONCLUSION AND INTERPRETATION: Mast cells are cellular actors of WAT inflammation and possibly fibrotic state found in obesity and diabetes. Whether mast cells could be involved in the pathophysiology of diabetes needs additional study as well as the positioning of these cells in driving pathological alterations of WAT in these chronic metabolic diseases.

Structural and inflammatory heterogeneity in subcutaneous adipose tissue: relation with liver histopathology in morbid obesity.

BACKGROUND & AIMS: In addition to total body fat, the regional distribution and inflammatory status of enlarged adipose tissue are strongly associated with metabolic co-morbidities of obesity. We recently showed that the severity of histological liver lesions related to obesity increases with the amount of macrophage accumulation in visceral adipose tissue (VAT), while no association was found with the subcutaneous adipose tissue (SAT). In the abdominal region, SAT is anatomically divided into two layers, i.e. superficial (sSAT) and deep (dSAT). The aim of the present study was to test the hypothesis that these distinct compartments differentially contribute to hepatic alterations in obesity. METHODS: Biopsies of the liver, sSAT, dSAT, and VAT were collected in 45 subjects with morbid obesity (age 43.7±1.6 years; BMI 48.5±1.2kg/m(2)) during bariatric surgery. Large scale gene expression analysis was performed to identify the pathways that discriminate sSAT from dSAT. Adipose tissue macrophages were quantified by immunohistochemistry using HAM56 antibody in subjects scored for liver histopathology. RESULTS: An inflammatory gene pattern discriminates between sSAT and dSAT. dSAT displayed an intermediate level of macrophage accumulation between sSAT and VAT. The abundance of macrophages in dSAT, but not in sSAT, was significantly increased in patients with non-alcoholic steatohepatitis (NASH) and/or fibroinflammatory hepatic lesions. CONCLUSIONS: These data show distinct gene signature and macrophage abundance in the two compartments of SAT, with dSAT more closely related to VAT than to sSAT in terms of inflammation and relation with the severity of liver diseases in morbid obesity.

[Adipose tissue, a new playground for immune cells]. / Le tissu adipeux - Un nouveau terrain de jeu pour les cellules immunitaires.

Adipose tissue has been under focus in the last decade and pivotal concepts have emerged from the studies of its complex biology. Low-grade inflammation both at the systemic level and in adipose tissue itself characterizes obesity. Among the different cell types contributing to inflammation, this review focuses on the mechanisms and consequences of macrophage accumulation in obese adipose tissue. Mechanisms for monocyte recruitment to adipose tissue, and how macrophages' phenotypes are modified in this environment in response to increasing fat mass, are considered. We review recent studies addressing the complex and versatile phenotype of adipose tissue macrophages that contribute to inflammatory and metabolic alterations, but could also help to maintain adipose tissue homeostasis in the setting of obesity both in mouse and human situations. A newly discovered consequence of adipose tissue inflammation is fibrosis. Whether macrophages and/or other immune cells exert a pro-fibrotic effect in adipose tissue is still unclear. This wealth of new information will hopefully help to design new ways to control adipose tissue inflammation and its deleterious sequels.

Variations in circulating inflammatory factors are related to changes in calorie and carbohydrate intakes early in the course of surgery-induced weight reduction.

BACKGROUND: Obesity is considered a low-grade inflammatory state that improves with weight loss. In addition to acute-phase proteins, other cytokines might contribute to systemic inflammation. OBJECTIVE: Our objective was to compare serum concentrations of a large panel of inflammation-related factors in obese and normal-weight subjects and to determine kinetic changes induced by caloric restriction. DESIGN: The cohort comprised 14 normal-weight women and 51 obese women who were followed over 2 y after Roux-en-Y gastric bypass. Multiplexed proteomics were used to simultaneously assay 27 cytokines and growth factors in serum. RESULTS: Concentrations of interleukin (IL)-9, IL-1-receptor antagonist, IL-10, interferon-γ-inducible protein 10, macrophage inflammatory protein 1ß, monocyte chemoattractant protein 1, IL-8, RANTES (regulated upon activation, normal T cell expressed and secreted), monokine induced by interferon-γ, and vascular endothelial growth factor were found to be elevated in obesity. IL-10 was further elevated in diabetic obese patients, whereas eotaxin was found to be higher only in diabetic subjects. After surgery, many factors showed a biphasic pattern of variation, decreasing sharply at month 3 before rising back to presurgical values at month 6; these changes closely tracked similar kinetic changes in calorie and carbohydrate intake. After 1 y, an overall reduction in cytokines accompanied the reduction in body mass index and an amelioration in metabolic status. CONCLUSIONS: Obesity is associated with elevated circulating concentrations of a large panel of cytokines. Coordinated kinetic changes during weight loss suggest an early influence of calorie and carbohydrate intakes, whereas a longer-term reduction in corpulence might prevail in regulating circulating cytokine concentrations. This trial is registered at clincaltrials.gov as NCT00476658.

Defining macrophage phenotype and function in adipose tissue.

In obesity, chronic low-grade inflammation is thought to mediate the effects of increased adipose tissue mass on metabolic comorbidity. Of the different cell types that contribute to obesity-induced inflammation in adipose tissue, this review focuses on macrophages and their monocytes precursors. Mechanisms for monocyte recruitment to adipose tissue, and how both monocytes and macrophages are phenotypically modified in this environment in response to increasing fat mass, are considered. The versatile phenotype of adipose tissue macrophages might contribute not only to inflammatory and metabolic alterations, but could also help to maintain adipose tissue homeostasis in the setting of obesity.

Pregravid obesity associates with increased maternal endotoxemia and metabolic inflammation.

Obese pregnant women develop severe insulin resistance and enhanced systemic and placental inflammation, suggesting associated modifications of endocrine and immune functions. Activation of innate immunity by endotoxins/lipopolysaccharides (LPS) has been proposed as a mechanism for enhancing metabolic alterations in disorders with insulin resistance. The aim of this study was to characterize the immune responses developed by the adipose tissue (AT) and their potential links to maternal endotoxemia in pregnancy with obesity. Blood and subcutaneous abdominal AT were obtained from 120 lean and obese women (term pregnancy) recruited at delivery. Gene expression was assessed in AT and stromal vascular cells isolated from a subset of 24 subjects from the same cohort. Doubling of plasma endotoxin concentrations indicated subclinical endotoxemia in obese compared with lean women. This was associated with significant increase in systemic C-reactive protein and interleukin-6 (IL-6) but not tumor necrosis factor-α (TNF-α) concentrations. AT inflammation was characterized by accumulation of CD68(+) macrophages with a threefold increased gene expression of the macrophage markers CD68, EMR1, and CD14. Gene expression for cytokines IL-6, TNF-α, IL-8, and monocyte chemotactic protein-1 (MCP1) and for LPS-sensing CD14, toll-like receptor 4 (TLR4), translocating chain-associated membrane protein 2 was 2.5-5-fold higher in stromal cells of obese compared to lean. LPS-treated cultured stromal cells of obese women expressed a 5-16-fold stimulation of the same cytokines upregulated in vivo. Our data demonstrate that subclinical endotoxemia is associated with systemic and AT inflammation in obese pregnant women. Recognition of bacterial pathogens may contribute to the combined dysfunction of innate immunity and the metabolic systems in AT.

Fibrosis in human adipose tissue: composition, distribution, and link with lipid metabolism and fat mass loss.

OBJECTIVE: Fibrosis is a newly appreciated hallmark of the pathological alteration of human white adipose tissue (WAT). We investigated the composition of subcutaneous (scWAT) and omental WAT (oWAT) fibrosis in obesity and its relationship with metabolic alterations and surgery-induced weight loss. RESEARCH DESIGN AND METHODS: Surgical biopsies for scWAT and oWAT were obtained in 65 obese (BMI 48.2 ± 0.8 kg/m(2)) and 9 lean subjects (BMI 22.8 ± 0.7 kg/m(2)). Obese subjects who were candidates for bariatric surgery were clinically characterized before, 3, 6, and 12 months after surgery, including fat mass evaluation by dual energy X-ray absorptiometry. WAT fibrosis was quantified and characterized using quantitative PCR, microscopic observation, and immunohistochemistry. RESULTS: Fibrosis amount, distribution and collagen types (I, III, and VI) present distinct characteristics in lean and obese subjects and with WAT depots localization (subcutaneous or omental). Obese subjects had more total fibrosis in oWAT and had more pericellular fibrosis around adipocytes than lean subjects in both depots. Macrophages and mastocytes were highly represented in fibrotic bundles in oWAT, whereas scWAT was more frequently characterized by hypocellular fibrosis. The oWAT fibrosis negatively correlated with omental adipocyte diameters (R = -0.30, P = 0.02), and with triglyceride levels (R = -0.42, P < 0.01), and positively with apoA1 (R = 0.25, P = 0.05). Importantly, scWAT fibrosis correlated negatively with fat mass loss measured at the three time points after surgery. CONCLUSIONS: Our data suggest differential clinical consequences of fibrosis in human WAT. In oWAT, fibrosis could contribute to limit adipocyte hypertrophy and is associated with a better lipid profile, whereas scWAT fibrosis may hamper fat mass loss induced by surgery.

Olanzapine-induced accumulation of adipose tissue is associated with an inflammatory state.

Second-generation antipsychotics are widely used in the treatment of all forms of psychoses, but they often produce undesirable side effects, among which are weight gain and other elements of metabolic syndrome. The mechanisms of these adverse effects are not known. The liver and adipose tissue are the principal candidate organs implicated in the development of antipsychotic-induced metabolic adverse effects. The present study investigated in the rat the effects on liver and white adipose tissue of a chronic treatment (46 days) with olanzapine 2 mg/kg or haloperidol 1 mg/kg, as compared with a control solution. In the liver, the expression of key genes involved in glucose transport and lipid metabolism and of regulatory transcription factors, as well as the TNFalpha gene, was not altered in response to either antipsychotic. Similarly, key genes involved in glucose transport and lipid metabolism were not changed in adipose tissue. However, the white adipose tissue was inflammatory in olanzapine-treated rats, with extensive macrophage infiltration and a significant increase in TNFalpha expression. In the plasma, TNFalpha and IL-1beta concentrations were slightly elevated. Chronic olanzapine treatment therefore produces a low-grade inflammatory state, likely initiated in the adipose tissue. Such an inflammatory state is known to be associated with an increased risk of insulin-resistance and cardiovascular diseases. This antipsychotic-induced inflammatory syndrome may participate in the inflammatory syndrome often observed in patients with schizophrenia. The strong and rather selective effect of olanzapine on TNFalpha expression may open new therapeutic opportunities for the prevention of olanzapine-induced metabolic abnormalities.

Cathepsins and cystatin C in atherosclerosis and obesity.

Given the increasing prevalence of human obesity worldwide, there is an urgent need for a better understanding of the molecular mechanisms linking obesity to metabolic and cardiovascular diseases. Our knowledge is nevertheless limited regarding molecules linking adipose tissue to downstream complications. The importance of cathepsins was brought to light in this context. Through a large scale transcriptomic analysis, our group recently identified the gene encoding cathepsin S as one of the most deregulated gene in the adipose tissue of obese subjects and positively correlated with body mass index. Other members of the cathepsin family are expressed in the adipose tissue, including cathepsin K and cathepsin L. Given their implication in atherogenesis, these proteases could participate into the well established deleterious relationship between enlarged adipose tissue and increased cardiovascular risk. Here, we review the clinical and experimental evidence relevant to the role of cathepsins K, L and S and their most abundant endogenous inhibitor, cystatin C, in atherosclerosis and in obesity.

Cathepsins in human obesity: changes in energy balance predominantly affect cathepsin s in adipose tissue and in circulation.

CONTEXT: Recent studies in humans and mice suggest the implication of the cysteine proteases cathepsins S, L, and K in vascular and metabolic complications of obesity. OBJECTIVE: Our objective was to identify clinically relevant forms of cathepsin in human obesity. DESIGN AND SETTING: We conducted a prospective study on two independent cohorts. PARTICIPANTS AND INTERVENTIONS: The first cohort includes 45 obese women eligible for gastric surgery (age, 39 +/- 1.6 yr; body mass index, 47 +/- 0.99 kg/m(2)) and 17 nonobese women (age, 38 +/- 1.8 yr; body mass index, 21 +/- 0.44 kg/m(2)). The second cohort comprises 29 obese women (age, 57 +/- 0.8 yr; body mass index, 34 +/- 0.69 kg/m(2)) undergoing 6 months of medically supervised caloric restriction. MAIN OUTCOMES: Cathepsin S, L, and K mRNA levels were determined in surgical adipose tissue biopsies. The proteins were measured in conditioned medium of adipose tissue explants and in circulation. RESULTS: Obese subjects had a 2-fold increase in cathepsin S mRNA in adipose tissue as compared with normal-weight subjects and an increased rate (1.5-fold) of cathepsin S release in adipose tissue explants. Cathepsin S circulating concentrations were increased with obesity (+30%) and reduced after weight reduction (P < 0.05 for both). By contrast, cathepsin L was unaffected in adipose tissue and serum; cathepsin K was undetectable in circulation and unchanged in adipose tissue. CONCLUSION: In humans, cathepsin S is more influenced than cathepsins L and K by changes in energy balance in adipose tissue and circulation. This opens new avenues to explore whether selective inhibition of this protease could reduce cardiovascular risk and ameliorate metabolic status in obese subjects.