Adipocyte produces matrix metalloproteinases 2 and 9: involvement in adipose differentiation

Reduction of Adipose Tissue Mass by the Angiogenesis Inhibitor ALS-L1023 from Melissa officinalis

It has been suggested that angiogenesis modulates adipogenesis and obesity. This study was undertaken to determine whether ALS-L1023 (ALS) prepared by a two-step organic solvent fractionation from Melissa leaves, which exhibits antiangiogenic activity, can regulate adipose tissue growth. The effects of ALS on angiogenesis and extracellular matrix remodeling were measured using in vitro assays. The effects of ALS on adipose tissue growth were investigated in high fat diet-induced obese mice. ALS inhibited VEGF- and bFGF-induced endothelial cell proliferation and suppressed matrix metalloproteinase (MMP) activity in vitro. Compared to obese control mice, administration of ALS to obese mice reduced body weight gain, adipose tissue mass and adipocyte size without affecting appetite. ALS treatment decreased blood vessel density and MMP activity in adipose tissues. ALS reduced the mRNA levels of angiogenic factors (VEGF-A and FGF-2) and MMPs (MMP-2 and MMP-9), whereas ALS increased the mRNA levels of angiogenic inhibitors (TSP-1, TIMP-1, and TIMP-2) in adipose tissues. The protein levels of VEGF, MMP-2 and MMP-9 were also decreased by ALS in adipose tissue. Metabolic changes in plasma lipids, liver triglycerides, and hepatic expression of fatty acid oxidation genes occurred during ALS-induced weight loss. These results suggest that ALS, which has antiangiogenic and MMP inhibitory activities, reduces adipose tissue mass in nutritionally obese mice, demonstrating that adipose tissue growth can be regulated by angiogenesis inhibitors.

Local adipocyte cancer cell paracrine loop: can "sick fat" be more detrimental?

This review article focuses on the emerging role of tumor resident adipocytes. It provides in vitro and in vivo evidence that they are essential for cancer development/progression. In addition to systemic effects, their tumor-promoting impact is dependent on local functions, notably via a complex adipocyte cancer cell paracrine loop (ACCPL). Indeed, this event leads to dramatic phenotypic and/or functional modifications of both cell types as well as of the extracellular matrix. Adipocytes undergo delipidation leading to adipocytes/cancer-associated adipocytes/cancer-associated fibroblasts de-differentiation processes. In turn, cancer cell aggressiveness is exacerbated through increased proliferation, migration, and invasion properties. This is accompanied by intense tissue remodeling, conducting to the occurrence of the tumor stroma. The molecular pathways involved in ACCPL remain largely unknown. Nevertheless, several clues are starting to emerge. Moreover, obesity is currently a sign of increased risk and poor prognosis in human carcinomas. How adiposopathy might impact tumors and specifically the ACCPL is still under investigation. However, available experimental, epidemiological, and clinical data allow to draw some directions. Interestingly, there are numerous similarities between the ACCPL-induced and obesity-related molecular alterations. It might, therefore, be hypothesized that obesity provides a "constitutively active" local permissive environment for cancer cells. Improving our knowledge about ACCPL in both lean and obese patients remains a challenging task. Indeed, deciphering the cellular and molecular mechanisms behind ACCPL might provide new targets for improving diagnosis/prognosis and the design of innovative therapeutic strategies, and even, in case of obesity, for preventing cancer.

Emerging markers of atherosclerosis before and after bariatric surgery

Objective

The objective of this study was to assess the emerging biochemical markers of arterial remodeling in patients with morbid obesity before and after surgical treatment and to compare the results to a control group.

Material and Methods

The prospective study included 40 patients with BMI 47.73 ± 6.18 kg/m², qualified for elective bariatric surgery and re-examined 6 months after the surgery. The control group consisted of non obese, age and sex matched 15 subjects. Following laboratory examinations were performed in all patients: basic laboratory examinations, MMP-2, MMP-9, adiponectin, PAI-1, CD40L, E-selectin.

Results

Examination of patients 6 m after bariatric surgery revealed a 34.57 ± 9.71 reduction in excess body weight. Comparison of the study group at two time points revealed differences in adiponectin, MMP-2 and MMP-9 levels. Hypoadiponectinemia was observed in 35 % patients 6 months after bariatric surgery compared to 90 % patients before the surgery. In addition, a strong correlation was observed between body fat mass and adiponectin levels (r = −0.504, p = 0.055). Moderate correlations were demonstrated between E-selectin levels and BMI (r = 0.361; p = 0.022), and metalloproteinase-9 levels (r = 0.326; p = 0.040). In addition, strong relationship was demonstrated between MMP-2 and MMP-9 (r = 0.502; p = 0.001), and moderate between MMP-2 and adiponectin levels (r = 0.449; p = 0.003). MMP-9 levels were moderately correlated with HDL-cholesterol levels (r = 0.316; p = 0.046).

Conclusions

Assessment of laboratory markers of arterial remodeling and metabolism suggest their adverse changes in patients with morbid obesity. However, body mass reduction due to bariatric surgery decreases inflammatory status, improves biochemical markers of arterial remodeling as well as to beneficial changes in the metabolism.

Serum SPARC and matrix metalloproteinase-2 and metalloproteinase-9 concentrations after bariatric surgery in obese adults

BACKGROUND

Remodeling of the extracellular matrix (ECM) of adipose tissue is regarded as part of the pathophysiology of obesity. Secreted protein acidic and rich in cysteine (SPARC) was the first ECM protein described in adipose tissue. Matrix metalloproteinases (MMPs) also play a role in ECM remodeling, and MMP-2 and MMP-9 may be associated with abnormal ECM metabolism. Here, we investigated changes in serum SPARC, MMP-2, and MMP-9 concentrations after bariatric surgery in obese adults.

METHODS

We recruited 34 obese patients who were scheduled to undergo bariatric surgery for weight loss. We analyzed changes in serum SPARC, MMP-2, and MMP-9 concentrations before and 9 months after bariatric surgery and any associations between changes in SPARC, MMP-2, and MMP-9 concentrations and obesity-related parameters.

RESULTS

Serum leptin levels significantly decreased, and the serum adiponectin level significantly increased after bariatric surgery. The serum SPARC concentration decreased significantly from 165.0 ± 18.2 to 68.7 ± 6.7 ng/mL (p < 0.001), and the MMP-2 concentration also decreased significantly from 262.2 ± 15.2 to 235.9 ± 10.5 ng/mL (p < 0.001). Changes in the serum SPARC concentration were significantly correlated with HOMA-IR changes, and changes in the serum MMP-9 concentration were found to inversely correlate with serum adiponectin changes.

CONCLUSION

These findings show that significant decreases in serum SPARC and MMP-2 concentrations occur after bariatric surgery. Our results thus suggest that weight loss via bariatric surgery could alter the ECM environment, and that these changes are related to certain metabolic changes.

Tissue Inhibitor Of Matrix Metalloproteinase-1 Is Required for High-Fat Diet-Induced Glucose Intolerance and Hepatic Steatosis in Mice

BACKGROUND

Plasma levels of tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) are elevated in obesity and obesity-related disorders, such as steatosis, but the metabolic role of TIMP-1 is unclear. Here we investigated how the presence or absence of TIMP-1 affected the development of diet-induced glucose intolerance and hepatic steatosis using the Timp1 null mice.

METHODS

Timp1 knockout (TKO) and wild type (TWT) mice were fed chow, high-fat diet (HFD) or intermediate fat and sucrose diet (IFSD). We determined body weight, body composition, lipid content of the liver, energy intake, energy expenditure, oral glucose tolerance, as well as insulin tolerance. In addition, the histology of liver and adipose tissues was examined and expression of selected genes involved in lipid metabolism and inflammation in liver and adipose tissues was determined by RT-qPCR.

RESULTS

TKO mice gained less weight and had lower energy efficiency than TWT mice when fed HFD, but not when fed chow or IFSD. Importantly, TKO mice were protected from development of HFD- as well as IFSD-induced glucose intolerance, hepatic steatosis, and altered expression of genes involved in hepatic lipid metabolism and inflammation.

CONCLUSION

Collectively, our results indicate that TIMP-1 contributes to the development of diet-induced hepatic steatosis and glucose intolerance and may be a potential therapeutic target.

Pathways commonly dysregulated in mouse and human obese adipose tissue: FAT/CD36 modulates differentiation and lipogenesis

Obesity is linked to adipose tissue hypertrophy (increased adipocyte cell size) and hyperplasia (increased cell number). Comparative analyses of gene datasets allowed us to identify 1426 genes which may represent common adipose phenotype in humans and mice. Among them we identified several adipocyte-specific genes dysregulated in obese adipose tissue, involved in either fatty acid storage (acyl CoA synthase ACSL1, hormone-sensitive lipase LIPE, aquaporin 7 AQP7, perilipin PLIN) or cell adhesion (fibronectin FN1, collagens COL1A1, COL1A3, metalloprotein MMP9, or both (scavenger receptor FAT/CD36). Using real-time analysis of cell surface occupancy on xCELLigence system we developed a new method to study lipid uptake and differentiation of mouse 3T3L1 fibroblasts and human adipose stem cells. Both processes are regulated by insulin and fatty acids such as oleic acid. We showed that fatty acid addition to culture media increased the differentiation rate and was required for full differentiation into unilocular adipocytes. Significant activation of lipogenesis, i.e. lipid accumulation, by either insulin or oleic acid was monitored in times ranging from 1 to 24 h, depending on differentiation state, whereas significant effects on adipogenesis, i.e., surperimposed lipid accumulation and gene transcriptional regulations were measured after 3 to 4 d. Combination of selected times for analysis of lipid contents, cell counts, size fractionations, and gene transcriptional regulations showed that FAT/CD36 specific inhibitor AP5258 significantly increased cell survival of oleic acid-treated mouse and human adipocytes, and partially restored the transcriptional response to oleic acid in the presence of insulin through JNK pathway. Taken together, these data open new perspectives to study the molecular mechanisms commonly dysregulated in mouse and human obesity at the level of lipogenesis linked to hypertrophy and adipogenesis linked to hyperplasia.

MFAP5 is related to obesity-associated adipose tissue and extracellular matrix remodeling and inflammation

OBJECTIVE

Low-grade inflammation is involved in adipose tissue (AT) and extracellular matrix (ECM) remodeling and induces deposition of ECM proteins in AT. We have previously shown that MFAP5 (microfibrillar-associated protein 5) expression decreases in AT after weight loss. The aim of this study was to investigate MFAP5 localization in human AT and gene expression in adipocytes and the role of MFAP5 in adipocyte metabolism and inflammation.

METHODS

MFAP5 protein localization and gene expression were studied with immunohistochemistry and quantitative reverse transcriptase PCR (RT-qPCR) in human subcutaneous AT and cultured Simpson-Golabi-Behmel syndrome (SGBS) adipocytes, respectively. The effect of MFAP5 knock-down by siRNA on gene expression and insulin action was examined with RT-qPCR, western blot, and insulin-stimulated glucose uptake. The effect of different cytokines on MFAP5 gene and protein expression was investigated in cultured human SGBS preadipocytes.

RESULTS

MFAP5 protein was highly expressed in AT, and gene expression decreased during adipocyte differentiation in SGBS cells. Treatment of preadipocytes with TNFα and TGFβ1 increased MFAP5 gene and protein expression. Furthermore, MFAP5 knock-down decreased the expression of genes involved in inflammation.

CONCLUSIONS

Our results demonstrate that factors involving low-grade inflammation modulate MFAP5 expression and that the modified expression of MFAP5 may further regulate AT inflammation.

Endostatin Prevents Dietary-Induced Obesity by Inhibiting Adipogenesis and Angiogenesis

Endostatin is a well-known angiogenesis inhibitor. Although angiogenesis has been considered as a potential therapeutic target of obesity, the inhibitory effect of endostatin on adipogenesis and dietary-induced obesity has never been demonstrated. Adipogenesis plays a critical role in controlling adipocyte cell number, body weight, and metabolic profile in a homeostatic state. Here we reveal that endostatin inhibits adipogenesis and dietary-induced obesity. The antiadipogenic mechanism of endostatin lies in its interaction with Sam68 RNA-binding protein in the nuclei of preadipocytes. This interaction competitively impairs the binding of Sam68 to intron 5 of mammalian target of rapamycin (mTOR), causing an error in mTOR transcript. This consequently decreases the expression of mTOR, results in decreased activities of the mTOR complex 1 pathway, and leads to defects in adipogenesis. Moreover, our findings demonstrate that the antiangiogenic function of endostatin also contributes to its obesity-inhibitory activity. Through the combined functions on adipogenesis and angiogenesis, endostatin prevents dietary-induced obesity and its related metabolic disorders, including insulin resistance, glucose intolerance, and hepatic steatosis. Thus, our findings reveal that endostatin has a potential application for antiobesity therapy and the prevention of obesity-related metabolic syndromes.

Role of extracellular matrix in development of skeletal muscle and postmortem aging of meat

The integrity of skeletal muscle is maintained by the intramuscular connective tissues (IMCTs) that are composed of extracellular matrix (ECM) molecules such as collagens, proteoglycans, and glycoproteins. The ECM plays an important role not only in providing biomechanical strength of the IMCT, but also in regulating muscle cell behavior. Some ECM molecules, such as decorin and laminin, modulate the activity of myostatin that regulates skeletal muscle mass. Furthermore, it has been shown that decorin activates Akt downstream of insulin-like growth factor-I receptor (IGF-IR) and enhances the differentiation of myogenic cells, suggesting that decorin acts as a signaling molecule to myogenic cells. With animal growth, the structural integrity of IMCT increases; collagen fibrils within the endomysium associate more closely with each other, and the collagen fibers in the perimysium become increasingly thick and their wavy pattern grows more regular. These changes increase the mechanical strength of IMCT, contributing to the toughening of meat. However, in highly marbled beef cattle like Wagyu, intramuscular fat deposits mainly in the perimysium between muscle fiber bundles during the fattening period. The development of adipose tissues appears to disorganize the structure of IMCT and contributes to the tenderness of Wagyu beef. The IMCT was considered to be rather immutable compared to myofibrils during postmortem aging of meat. However, several studies have shown that collagen networks in the IMCT are disintegrated and proteoglycan components are degraded during postmortem aging. These changes in ECM appear to reduce the mechanical strength of IMCT and contribute to the tenderness of uncooked meat or cooked meat at low temperature. Thus, the ECM plays a multifunctional role in skeletal muscle development and postmortem aging of meat.

Trophic effects of adipose derived stem cells on Langerhans islets viability--Review

Langerhans islets transplantation has been proposed to provide an endogenous source of insulin in Type I diabetes. However, the hypoxic stress and the receptor's immune reaction suffered by the implants cause them to fail in sustaining the insulin production along the time. Experimental studies have shown that adipose derived stem cells (ADSCs) can secrete cytokines that activate free radical scavengers, antioxidants and chaperone heat/shock proteins leading to reduction of apoptosis in damaged tissues. Therefore, using the PubMed database, we reviewed the experimental studies that investigated the trophic effects of ADSCs on Langerhans islets viability, in vitro and in vivo, from 2009 to 2014. We excluded articles that investigated the effects of other types of mesenchymal stem cells on β-cell survival as well articles that worked in the differentiation of ADSCs into insulin producing cells. The analysis of the experiments revealed that exposure of islets to ADSCs in vitro, even for a short period of time, can enhance islet cell viability and function. In vivo studies also corroborated the trophic effects of ADSCs leading to the improvement of islet function and reduction of the number of the islets required for controlling the receptor's glucose levels. This review can contribute to guide future experiments looking for a long term diabetes treatment employing ADSC trophic effects for the enhancement of transplanted Langerhans islet viability and functioning.

A study on quantitative structure-activity relationship and molecular docking of metalloproteinase inhibitors based on L-tyrosine scaffold

Background

MMP-2 enzyme is a kind of matrix metalloproteinases that digests the denatured collagens and gelatins. It is highly involved in the process of tumor invasion and has been considered as a promising target for cancer therapy. The structural requirements of an MMP-2 inhibitor are: (1) a functional group that binds the zinc ion, and (2) a functional group which interacts with the enzyme backbone and the side chains which undergo effective interactions with the enzyme subsites.

Methods

In the present study, a QSAR model was generated to screen new inhibitors of MMP-2 based on L–hydroxy tyrosine scaffold. Descriptors generation were done by Hyperchem 8, DRAGON and Gaussian98W programs. SPSS and MATLAB programs have been used for multiple linear regression (MLR) and genetic algorithm partial least squares (GA-PLS) analyses and for theoretical validation. Applicability domain of the model was performed to screen new compounds. The binding site potential of all inhibitors was verified by structure-based docking according to their binding energy and then the best inhibitors were selected.

Results

The best QSAR models in MLR and GA-PLS were reported, with the square correlation coefficient for leave-one-out cross-validation (Q²_LOO) larger than 0.921 and 0.900 respectively. The created MLR and GA-PLS models indicated the importance of molecular size, degree of branching, flexibility, shape, three-dimensional coordination of different atoms in a molecule in inhibitory activities against MMP-2.

The docking study indicated that lipophilic and hydrogen bonding interactions among the inhibitors and the receptor are involved in a ligand-receptor interaction. The oxygen of carbonyl and sulfonyl groups is important for hydrogen bonds of ligand with Leu82 and Ala83. R₂ and R₃ substituents play a main role in hydrogen bonding interactions. R₁ is sited in the hydrophobic pocket. Methylene group can help a ligand to be fitted in the lipophilic pocket, so two methylene groups are better than one. The Phenyl group can create a π-π interaction with Phe86.

Conclusions

The QSAR and docking analyses demonstrated to be helpful tools in the prediction of anti-cancer activities and a guide to the synthesis of new metalloproteinase inhibitors based on L-tyrosine scaffold.

A study on quantitative structure–activity relationship and molecular docking of metalloproteinase inhibitors based on L-tyrosine scaffold

Background

MMP-2 enzyme is a kind of matrix metalloproteinases that digests the denatured collagens and gelatins. It is highly involved in the process of tumor invasion and has been considered as a promising target for cancer therapy. The structural requirements of an MMP-2 inhibitor are: (1) a functional group that binds the zinc ion, and (2) a functional group which interacts with the enzyme backbone and the side chains which undergo effective interactions with the enzyme subsites.

Methods

In the present study, a QSAR model was generated to screen new inhibitors of MMP-2 based on L–hydroxy tyrosine scaffold. Descriptors generation were done by Hyperchem 8, DRAGON and Gaussian98W programs. SPSS and MATLAB programs have been used for multiple linear regression (MLR) and genetic algorithm partial least squares (GA-PLS) analyses and for theoretical validation. Applicability domain of the model was performed to screen new compounds. The binding site potential of all inhibitors was verified by structure-based docking according to their binding energy and then the best inhibitors were selected.

Results

The best QSAR models in MLR and GA-PLS were reported, with the square correlation coefficient for leave-one-out cross-validation (Q2 LOO) larger than 0.921 and 0.900 respectively. The created MLR and GA-PLS models indicated the importance of molecular size, degree of branching, flexibility, shape, three-dimensional coordination of different atoms in a molecule in inhibitory activities against MMP-2.

The docking study indicated that lipophilic and hydrogen bonding interactions among the inhibitors and the receptor are involved in a ligand-receptor interaction. The oxygen of carbonyl and sulfonyl groups is important for hydrogen bonds of ligand with Leu82 and Ala83. R2 and R3 substituents play a main role in hydrogen bonding interactions. R1 is sited in the hydrophobic pocket. Methylene group can help a ligand to be fitted in the lipophilic pocket, so two methylene groups are better than one. The Phenyl group can create a π-π interaction with Phe86.

Conclusions

The QSAR and docking analyses demonstrated to be helpful tools in the prediction of anti-cancer activities and a guide to the synthesis of new metalloproteinase inhibitors based on L-tyrosine scaffold.

Gelatinase A (MMP-2) promotes murine adipogenesis

BACKGROUND

Expansion of adipose tissue is dependent on adipogenesis, angiogenesis and extracellular matrix remodeling. A functional role in these processes was suggested for the gelatinase subfamily of the matrix metalloproteinases. Here, we have evaluated a potential role of gelatinase A (MMP-2) in adipogenesis.

METHODS

Murine embryonic fibroblasts (MEF) were derived from wild-type or MMP-2 deficient mice. Genetic manipulation of Mmp2 (shRNA-knockdown or overexpression) was performed in 3T3-F442A preadipocytes. Cell cultures were subjected to an adipogenic medium. As an in vivo model for de novo adipogenesis, 3T3-F442A preadipocytes with or without knockdown were injected subcutaneously in Nude BALB/c mice kept on high fat diet.

RESULTS

Mmp2 deficient MEF, as compared to controls, showed significantly impaired differentiation into mature adipocytes, as demonstrated by 90% reduced intracellular lipid content and reduced expression of pro-adipogenic markers. Moreover, selective Mmp2 knockdown in 3T3-F442A preadipocytes resulted in significantly reduced differentiation. In contrast, overexpression of Mmp2 resulted in markedly enhanced differentiation. In de novo formed fat pads resulting from preadipocytes with Mmp2 knockdown expression of aP2, Ppar-γ and adiponectin was significantly lower, and collagen was more preserved. The fat pad weights as well as size and density of adipocytes or blood vessels were, however, not significantly different from controls.

CONCLUSION

Our data directly support a functional role of MMP-2 in adipogenesis in vitro, and suggest a potential role in in vivo adipogenesis.

GENERAL SIGNIFICANCE

Selective modulation of MMP-2 levels affects adipogenesis.

Immunological blockade of adipocyte inflammation caused by increased matrix metalloproteinase-cleaved osteopontin in obesity

OBJECTIVE

Osteopontin (OPN) is upregulated in adipose tissue (AT) in obesity and contributes to subclinical inflammation, adipocyte dysfunction, and insulin resistance. OPN effects can be increased by cleavage by matrix metalloproteinases (MMP). This study aimed at investigating the presence of OPN cleavage products in human AT in obesity and their impact on adipocyte function and immunological blockade of these effects.

METHODS

AT of severely obese and control donors was investigated for OPN and MMP expression and the presence of OPN cleavage fragments. Primary adipocytes were isolated from human donors for in vitro investigation of cleaved OPN effects.

RESULTS

OPN and MMP-9 expression was highly correlated in AT from obese donors, and increased levels of cleaved OPN were detected in AT from obese individuals. The in vitro effect of OPN on adipocyte inflammation and insulin resistance was enhanced by protease cleavage, which could finally be blocked with a monoclonal antibody directed against the MMP cleavage site of OPN.

CONCLUSIONS

These findings show that MMP cleavage of OPN in AT occurs in obesity, thereby enhancing OPN's inflammatory and pro-diabetic activity on adipocytes. Specifically targeting MMP-cleaved OPN opens avenues for prevention and treatment of obesity-induced type 2 diabetes.

Postprandial adiponectin and gelatinase response to a high-fat versus an isoenergetic low-fat meal in lean, healthy men

OBJECTIVE

Evidence suggests that an acute systemic inflammatory response is invoked after consumption of a high-energy meal. Postprandial regulation of adiponectin, an adipose tissue-derived, anti-inflammatory hormone, and the gelatinases, matrix metalloproteinase (MMP)-2 and MMP-9, endopeptidases implicated in a diverse range of inflammatory processes, remain inconclusive. The aim of this study was to assess the postprandial effect of a high-energy (1212 kcal) meal on plasma adiponectin, MMP-2 and MMP-9 activity, glucose, insulin, triacylglycerols, total cholesterol, high-density lipoprotein cholesterol, and the differential effects on these parameters depending on whether the test meal was high fat (HF; 46 g fat, 1210 kcal) or isoenergetic and low fat (LF; 15 g fat, 1214 kcal energy).

METHODS

Test meals were consumed by 17 lean, healthy men on two separate occasions with blood samples collected by venipuncture at baseline (0 h) and 1 and 3 h after consumption of each test meal.

RESULTS

At baseline, no significant difference was seen in the parameters between the two groups, except for MMP-2, MMP-9, and total cholesterol. Over the 3-h postprandial period, no significant differential effect of the HF versus the LF test meal was observed on adiponectin, MMP-2, MMP-9, or on metabolic markers other than triacylglycerol, which increased significantly in response to the HF test meal (time × treatment, P = 0.002). When analyzed independent of time, MMP-2 (treatment, P = 0.006), MMP-9 (treatment, P = 0.022), and glucose (treatment, P = 0.026) were lower after consumption of the HF meal compared with the LF test meal. When analyzed independent of treatment, adiponectin increased over the 3-h postprandial period (time, P = 0.031), but there was no change in MMP-2 or MMP-9 (time, P = 0.503 and P = 0.525, respectively). Over the 3-h postprandial period, insulin (time, P < 0.001) and total cholesterol (time, P = 0.002) increased, whereas glucose (time, P < 0.001) and high-density lipoprotein cholesterol (time, P < 0.001) decreased.

CONCLUSION

No differential effects of a HF versus a LF isoenergetic meal were seen on postprandial adiponectin or the gelatinases. Adiponectin increased in response to a high-energy meal independent of treatment, and the gelatinases were lower in response to the HF versus the LF isoenergetic meal, independent of time point. Given the considerable amount of time that humans spend in the postprandial state, additional research is necessary to further understand inflammatory changes in this state.

Inhibition of MMP-13 prevents diet-induced obesity in mice and suppresses adipogenesis in 3T3-L1 preadipocytes

Adipose tissue remodeling by the matrix metalloproteases (MMPs) is critical for tissue hypertrophy and obesity. MMP-13 is an important protein that is highly expressed in adipose tissue but whose potential role in adipose tissue expansion is poorly characterized. We investigated the effect of pharmacological inhibition of MMP-13 with a selective inhibitor, CP-544439, on adipose tissue mass in mice on a high fat diet, and determined the effect of the inhibitor during in vitro adipocyte differentiation of 3T3-L1 cells. CP-544439 was administered for 6 weeks to mice on a high fat diet. Body adiposity and glucose tolerance was determined. Differentiating 3T3-L1 adipocytes were also treated with the inhibitor for a maximum of 8 days and adipogenesis assessed. Treatment of mice with the inhibitor resulted in reduction in body adiposity and improvement in glucose clearance. Histological examination of epididymal adipose showed reduced adipocyte hypertrophy accompanied by increased staining for collagen in the inhibitor treated mice. Treatment of differentiating 3T3-L1 cells with the inhibitor resulted in reduced adipocyte differentiation. Knockdown of MMP-13 using small interfering RNA in differentiating 3T3-L1 cells reduced adipocyte differentiation indicated by reduced expression of PPARγ. These results suggest that MMP-13 may play a major role in adipose development and its inhibition could be a potential strategy to prevent obesity.

Acute eccentric resistance exercise decreases matrix metalloproteinase activity in obese elderly women

The association of ageing with obesity commits elderly women and has been correlated with multiple degenerative processes, which could be occasioned by an enhancing in levels of matrix metalloproteinase-2 and metalloproteinase-9 (MMPs) as well by an cytokine unbalance that included an enhancing on interleukin-6 (IL-6). Furthermore, other factors could be also related to degenerative process, as they could be reduced by eccentric resistance exercise (ERE), which seems particularly important to initiate resistance training in obese older adults. In this view, this study aims to determinate the effects of an acute ERE session on serum MMP-2, MMP-9 and IL-6 in elderly obese women. Ten elderly obese women participated in this study and completed a 10 repetitions maximum test (10 RM) utilizing leg extension exercise. Subjects then completed an acute ERE session consisting of seven sets of 10 repetitions at 110% of 10 RM with a rest of 3 min between sets. Blood samples were collected before, immediately after, 3, 24 and 48 h following the ERE session. Zymograms were utilized to measure the MMP-2 and MMP-9 enzymes from all individuals. Moreover, IL-6 concentration was also determinated. After ERE session, MMP-2 and MMP-9 decreased, remaining significantly below baseline values after 48 h (P<0·05). Although not statistically significant, there was a tendency for IL-6 to decrease 48 h after the ERE when compared with 3 h (P = 0·06). An acute ERE session decreases MMP-9, MMP-2 and IL-6 in elderly obese women, possibly indicating a transient protection against the low grade inflammation present in this specific population.

Adipose tissue dysregulation and metabolic consequences in childhood and adolescent obesity: potential impact of dietary fat quality

Evidence suggests that at a population level, childhood and adolescent obesity increase the long-term risk of chronic diseases such as type 2 diabetes and CVD. At an individual level, however, the metabolic consequences of obesity in youth vary immensely. Despite comparable BMI, some adolescents develop impaired glucose tolerance while others maintain normal glucose homeostasis. It has been proposed that the variation in the capacity to store lipid in the subcutaneous adipose tissue (SAT) may partially discriminate metabolically healthy from unhealthy obesity. In positive energy balance, a decreased capacity to expand SAT may drive lipid accumulation to visceral adipose tissue, liver and skeletal muscle. This state of lipotoxicity is associated with chronic low-grade inflammation, insulin resistance and dyslipidaemia. The present review examines the differential adipose tissue development and function in children and adolescents who exhibit metabolic dysregulation compared with those who are protected. Additionally, the role of manipulating dietary fat quality to potentially prevent and treat metabolic dysfunction in obesity will be discussed. The findings of the present review highlight the need for further randomised controlled trials to establish the effect of dietary n-3 PUFA on the metabolic phenotype of obese children and adolescents. Furthermore, using a personalised nutrition approach to target interventions to those at risk of, or those with established metabolic dysregulation may optimise the efficacy of modifying dietary fat quality.

Gender-specific genetic associations of polymorphisms in ACE, AKR1C2, FTO and MMP2 with weight gain over a 10-year period

Weight gain, when it leads to overweight or obesity, is nowadays one of the major health problems. ACE, FTO, AKR1C2, TIMP4 and MMP2 genes have been implicated in previous studies on weight regulation. This study investigated the contribution of polymorphisms in these five candidate genes to the risk of weight gain over a 10-year time period. Two groups were selected from participants of the Doetinchem cohort study who were followed over a 10-year period: A stable weight group (±2 kg/10 year; n = 259) and a weight gainers group who increased their body weight by roughly 10 % (>8 kg/10 year; n = 237). Starting BMI was between 20 and 35 kg/m(2) and baseline age between 20 and 45 years. Selected SNPs and insert/deletion in candidate genes were measured in each group. In men, the allelic distribution of FTO rs9939609 (χ (2) p = 0.005), ACE rs4340 (χ (2) p = 0.006) and AKR1C2 rs12249281 (χ (2) p = 0.019) differed between the weight stable and weight gainers group. Interaction between FTO rs9939609 and ACE rs4340 was observed. In women, the allelic distribution of MMP2 rs1132896 differed between the weight stable and weight gainers group (χ (2) p = 0.00001). The A-allele of FTO was associated with a 1.99× higher risk of gaining weight in men (OR 1.99, p = 0.020), while in women, the C-allele of MMP2 was associated with a 2.50× higher risk of weight gain (OR 2.50, p = 0.001) over the 10-year period. We found that FTO in men and MMP2 in women are associated with weight gain over a 10-year follow-up period.

Adipocyte hypertrophy, inflammation and fibrosis characterize subcutaneous adipose tissue of healthy, non-obese subjects predisposed to type 2 diabetes

Background

The adipose tissue is important for development of insulin resistance and type 2 diabetes and adipose tissue dysfunction has been proposed as an underlying cause. In the present study we investigated presence of adipocyte hypertrophy, and gene expression pattern of adipose tissue dysfunction in the subcutaneous adipose tissue of healthy, non-obese subjects predisposed to type 2 diabetes compared to matched control subjects with no known genetic predisposition for type 2 diabetes.

Method

Seventeen healthy and non-obese subjects with known genetic predisposition for type 2 diabetes (first-degree relatives, FDRs) and 17 control subjects were recruited. The groups were matched for gender and BMI and had similar age. Glucose tolerance was determined by an oral glucose tolerance test and insulin sensitivity was calculated using HOMA-index. Blood samples were collected and subcutaneous abdominal adipose tissue biopsies obtained for gene expression analysis and adipocyte cell size measurement.

Results

Our findings show that, in spite of similar age, BMI and percent body fat, FDRs displayed adipocyte hypertrophy, as well as higher waist/hip ratio, fasting insulin levels, HOMA-IR and serum triglycerides. Adipocyte hypertrophy in the FDR group, but not among controls, was associated with measures of impaired insulin sensitivity. The adipocyte hypertrophy was accompanied by increased inflammation and Wnt-signal activation. In addition, signs of tissue remodeling and fibrosis were observed indicating presence of early alterations associated with adipose tissue dysfunction in the FDRs.

Conclusion

Genetic predisposition for type 2 diabetes is associated with impaired insulin sensitivity, adipocyte hypertrophy and other markers of adipose tissue dysfunction. A dysregulated subcutaneous adipose tissue may be a major susceptibility factor for later development of type 2 diabetes.

Promotion of adipogenesis by an EP2 receptor agonist via stimulation of angiogenesis in pulmonary emphysema

Body weight loss is a common manifestation in patients with chronic obstructive pulmonary disease (COPD), particularly those with severe emphysema. Adipose angiogenesis is a key mediator of adipogenesis and use of pro-angiogenic agents may serve as a therapeutic option for lean COPD patients. Since angiogenesis is stimulated by PGE2, we examined whether ONO-AE1-259, a selective E-prostanoid (EP) 2 receptor agonist, might promote adipose angiogenesis and adipogenesis in a murine model of elastase-induced pulmonary emphysema (EIE mice). Mice were intratracheally instilled with elastase or saline, followed after 4 weeks by intraperitoneal administration of ONO-AE1-259 for 4 weeks. The subcutaneous adipose tissue (SAT) weight decreased in the EIE mice, whereas in the EIE mice treated with ONO-AE1-259, the SAT weight was largely restored, which was associated with significant increases in SAT adipogenesis, angiogenesis, and VEGF protein production. In contrast, ONO-AE1-259 administration induced no alteration in the weight of the visceral adipose tissue. These results suggest that in EIE mice, ONO-AE1-259 stimulated adipose angiogenesis possibly via VEGF production, and thence, adipogenesis. Our data pave the way for the development of therapeutic interventions for weight loss in emphysema patients, e.g., use of pro-angiogenic agents targeting the adipose tissue vascular component.

NOD1 expression is increased in the adipose tissue of women with gestational diabetes

Maternal peripheral insulin resistance and increased inflammation are two features of pregnancies, complicated by gestational diabetes mellitus (GDM). The nucleotide-binding oligomerisation domain (NOD) intracellular molecules recognise a wide range of microbial products, as well as other intracellular danger signals, thereby initiating inflammation through activation of nuclear factor κB (NFκB). The aim of this study was to determine whether levels of NOD1 and NOD2 are increased in adipose tissue of women with GDM. The effect of NOD1 and NOD2 activation on inflammation and the insulin signalling pathway was also assessed. NOD1, but not NOD2, expression was higher in omental and subcutaneous adipose tissues obtained from women with GDM when compared with those from women with normal glucose tolerance (NGT). In both omental and subcutaneous adipose tissues from NGT and GDM women, the NOD1 ligand g-d-glutamyl-meso-diaminopimelic acid (iE-DAP) significantly induced the expression and secretion of the pro-inflammatory cytokine interleukin 6 (IL6) and chemokine IL8; COX2 (PTGS2) gene expression and subsequent prostaglandin production; the expression and secretion of the extracellular matrix remodelling enzyme matrix metalloproteinase 9 (MMP9) and the gene expression and secretion of the adhesion molecules ICAM1 and VCAM1. There was no effect of the NOD2 ligand muramyl dipeptide on any of the endpoints tested. The effects of the NOD1 ligand iE-DAP were mediated via NFκB, as the NFκB inhibitor BAY 11-7082 significantly attenuated iE-DAP-induced expression and secretion of pro-inflammatory cytokines, COX2 gene expression and subsequent prostaglandin production, MMP9 expression and secretion and ICAM1 and VCAM1 gene expression and secretion. In conclusion, the present findings describe an important role for NOD1 in the development of insulin resistance and inflammation in pregnancies complicated by GDM.

Osteopontin deletion prevents the development of obesity and hepatic steatosis via impaired adipose tissue matrix remodeling and reduced inflammation and fibrosis in adipose tissue and liver in mice

Osteopontin (OPN) is a multifunctional extracellular matrix (ECM) protein involved in multiple physiological processes. OPN expression is dramatically increased in visceral adipose tissue in obesity and the lack of OPN protects against the development of insulin resistance and inflammation in mice. We sought to unravel the potential mechanisms involved in the beneficial effects of the absence of OPN. We analyzed the effect of the lack of OPN in the development of obesity and hepatic steatosis induced by a high-fat diet (HFD) using OPN-KO mice. OPN expression was upregulated in epididymal white adipose tissue (EWAT) and liver in wild type (WT) mice with HFD. OPN-KO mice had higher insulin sensitivity, lower body weight and fat mass with reduced adipose tissue ECM remodeling and reduced adipocyte size than WT mice under a HFD. Reduced MMP2 and MMP9 activity was involved in the decreased ECM remodeling. Crown-like structure number in EWAT as well as F4/80-positive cells and Emr1 expression in EWAT and liver increased with HFD, while OPN-deficiency blunted the increase. Moreover, our data show for the first time that OPN-KO under a HFD mice display reduced fibrosis in adipose tissue and liver, as well as reduced oxidative stress in adipose tissue. Gene expression of collagens Col1a1, Col6a1 and Col6a3 in EWAT and liver, as well as the profibrotic cytokine Tgfb1 in EWAT were increased with HFD, while OPN-deficiency prevented this increase. OPN deficiency prevented hepatic steatosis via reduction in the expression of molecules involved in the onset of fat accumulation such as Pparg, Srebf1, Fasn, Mogat1, Dgat2 and Cidec. Furthermore, OPN-KO mice exhibited higher body temperature and improved BAT function. The present data reveal novel mechanisms of OPN in the development of obesity, pointing out the inhibition of OPN as a promising target for the treatment of obesity and fatty liver.

Expression of adipocyte biomarkers in a primary cell culture models reflects preweaning adipobiology

A cohort of genes was selected to characterize the adipogenic phenotype in primary cell cultures from three tissue sources. We compared the quantitative expression of biomarkers in culture relative to their expression in vivo because the mere presence or absence of expression is minimally informative. Although all biomarkers analyzed have biochemical functions in adipocytes, the expression of some of the biomarkers varied enormously in culture relative to their expression in the adult fat tissues in vivo, i.e. inguinal fat for white adipocytes and brite cells, interscapular brown adipose tissue for brown adipocytes, and ear mesenchymal stem cells for white adipocytes from adult mice. We propose that the pattern of expression in vitro does not reflect gene expression in the adult mouse; rather it is predominantly the expression pattern of adipose tissue of the developing mouse between birth and weaning. The variation in gene expression among fat depots in both human and rodent has been an extensively studied phenomenon, and as recently reviewed, it is related to subphenotypes associated with immune function, the inflammatory response, fat depot blood flow, and insulin sensitivity. We suggest that adipose tissue biology in the period from birth to weaning is not just a staging platform for the emergence of adult white fat but that it has properties to serve the unique needs of energy metabolism in the newborn. A case in point is the differentiation of brite cells that occurs during this period followed by their involution immediately following weaning.

Biomarkers in the field of obesity and its related comorbidities

INTRODUCTION

The prevalence of obesity has increased dramatically in the last decades both in children and adults and is now considered a major health problem. It is associated with numerous comorbidities such as hypertension, dyslipidemia, diabetes and subsequent cardiovascular disease (CVD). One of the mechanisms that connect obesity with these comorbidities is the secretion of so-called adipocytokines or adipokines by the adipose tissue itself. Most adipokines with pro-inflammatory properties are overproduced with increasing adiposity, whereas some adipokines with anti-inflammatory or insulin-sensitizing properties, like adiponectin, are decreased. This dysregulation of adipokines production may promote obesity-linked metabolic disorders and CVD. Except adipokines a wide complex network of chemicals balances pro-inflammatory and anti-inflammatory effects.

AREAS COVERED

In this review, we summarize the role of various adipokines and other chemicals associated with obesity and its related cardiometabolic comorbidities, with a special focus on recent evidence showing their potential role as biomarkers whose expression are indicative of obesity and its complications.

EXPERT OPINION

Biomarkers associated with obesity, type 2 diabetes (T2D) and CVD could prove beneficial for early identification, proper treatment and good life assurance. Unfortunately, the complexity of biological pathways interactions is such that further research is necessary before any of these markers could reach an accurate diagnostic value.

Gelatinase B (MMP-9) gene silencing does not affect murine preadipocyte differentiation

Growth of adipose tissue involves differentiation of preadipocytes into mature lipid-containing adipocytes. The matrix metalloproteinases (MMPs) are known regulators of adipose tissue biology, and previous studies suggested a key role for gelatinase B (MMP-9) in adipogenesis. In the present study we have evaluated a potential functional role of MMP-9 by performing gene silencing in 3T3-F442A preadipocytes. At the end of a 12-day differentiation period, no significant differences were observed between MMP-9 knockdown cells and the control cells with respect to intracytoplasmatic lipid content, or expression of the adipogenic markers aP2, PPARγ, Lpl, and adiponectin, or of the preadipocyte marker Pref-1. Thus, in vitro differentiation of 3T3-F442A preadipocytes into mature adipocytes is not significantly affected by the loss of MMP-9.

Modulation of adipose tissue inflammation by FOXP3+ Treg cells, IL-10, and TGF-β in metabolically healthy class III obese individuals

OBJECTIVE

The objective of this study was to compare the profiles of proinflammatory (interleukin [IL]-6 and tumor necrosis factor [TNF]) and anti-inflammatory (IL-10 and transforming growth factor [TGF]-β) adipokines in the blood, subcutaneous adipose tissue (SAT), and visceral adipose tissue (VAT) of metabolically healthy class III obese individuals and normal-weight controls.

METHODS

The serum concentrations (enzyme-linked immunosorbent assay [ELISA]), mRNA expression levels (reverse transcriptase polymerase chain reaction), and adipose tissue secretion (ELISA) of IL-6, TNF, IL-10, and TGF-β were analyzed, as were the mRNA expression of FOXP3 (present in regulatory T cells) and the secretion (Western blotting) of matrix metalloproteinases in the adipose tissue.

RESULTS

There were no differences in the circulating levels, expression, or secretion of IL-6 and TNF between the groups or tissues. The expression and circulating levels of IL-10 were higher in obese individuals, especially in the SAT. Although the blood concentration of TGF-β was similar between the groups, its expression and secretion levels were higher in the adipose tissues of obese individuals compared with controls. FOXP3 and MMP expression levels were higher in the SAT and VAT of obese individuals, respectively, compared with the controls.

CONCLUSION

Metabolically healthy, extremely obese individuals have effective immunoregulation to counter chronic obesity-related inflammation through the increased production of the anti-inflammatory cytokines IL-10 and TGF-β in adipose tissue, especially SAT; the increased presence of FOXP3-positive regulatory T cells; and increases in angiogenesis and adipogenesis induced by TGF-β and MMPs. These regulatory mechanisms could be important in the delayed onset of metabolic complications, even in extremely obese individuals.

Macromolecular crowding amplifies adipogenesis of human bone marrow-derived mesenchymal stem cells by enhancing the pro-adipogenic microenvironment

The microenvironment plays a vital role in both the maintenance of stem cells in their undifferentiated state (niche) and their differentiation after homing into new locations outside this niche. Contrary to conventional in-vitro culture practices, the in-vivo stem cell microenvironment is physiologically crowded. We demonstrate here that re-introducing macromolecular crowding (MMC) at biologically relevant fractional volume occupancy during chemically induced adipogenesis substantially enhances the adipogenic differentiation response of human bone marrow-derived mesenchymal stem cells (MSCs). Both early and late adipogenic markers were significantly up-regulated and cells accumulated 25-40% more lipid content under MMC relative to standard induction cocktails. MMC significantly enhanced deposition of extracellular matrix (ECM), notably collagen IV and perlecan, a heparan sulfate proteoglycan. As a novel observation, MMC also increased the presence of matrix metalloproteinase -2 in the deposited ECM, which was concomitant with geometrical ECM remodeling typical of adipogenesis. This suggested a microenvironment that was richer in both matrix components and associated ligands and was conducive to adipocyte maturation. This assumption was confirmed by seeding undifferentiated MSCs on decellularized ECM deposited by adipogenically differentiated MSCs, Adipo-ECM. On Adipo-ECM generated under crowding, MSCs differentiated much faster under a classical differentiation protocol. This was evidenced throughout the induction time course, by a significant up-regulation of both early and late adipogenic markers and a 60% higher lipid content on MMC-generated Adipo-ECM in comparison to standard induction on tissue culture plastic. This suggests that MMC helps build and endow the nascent microenvironment with adipogenic cues. Therefore, MMC initiates a positive feedback loop between cells and their microenvironment as soon as progenitor cells are empowered to build and shape it, and, in turn, are informed by it to respond by attaining a stable differentiated phenotype if so induced. This work sheds new light on the utility of MMC to tune the microenvironment to augment the generation of adipose tissue from differentiating human MSCs.

The beneficial role of vitamin D in obesity: possible genetic and cell signaling mechanisms

The prevalence rates of overweight and obesity are considered an important public issue in the United States, and both of these conditions are increasing among both children and adults. There is evidence of aberrations in the vitamin D-endocrine system in obese subjects. Vitamin D deficiency is highly prevalent in patients with obesity, and many studies have demonstrated the significant effect of calcitriol on adipocytes. Genetic studies have provided an opportunity to determine which proteins link vitamin D to obesity pathology, including the vitamin D receptor, toll-like receptors, the renin-angiotensin system, apolipoprotein E, vascular endothelial growth factor, and poly (ADP-ribose) polymerase-1. Vitamin D also exerts its effect on obesity through cell-signaling mechanisms, including matrix metalloproteinases, mitogen-activated protein kinase pathways, the reduced form of nicotinamide adenine dinucleotide phosphate, prostaglandins, reactive oxygen species, and nitric oxide synthase.

In conclusion, vitamin D may have a role in obesity. The best form of vitamin D for use in the obese individuals is calcitriol because it is the active form of the vitamin D₃ metabolite, its receptors are present in adipocytes, and modulates inflammatory cytokine expression.

Why cellular stress suppresses adipogenesis in skeletal tissue, but is ineffective in adipose tissue: control of mesenchymal cell differentiation via integrin binding sites in extracellular matrices

This Perspective addresses one of the major puzzles of adipogenesis in adipose tissue, namely its resistance to cellular stress. It introduces a concept of "density" of integrin binding sites in extracellular matrix, proposes a cellular signaling explanation for the observed effects of matrix elasticity and of cell shape on mesenchymal stem cell differentiation, and discusses how specialized integrin binding sites in collagen IV-containing matrices guard two pivotal physiological and evolutionary processes: stress-resistant adipogenesis in adipose tissues and preservation of pluripotency of mesenchymal stem-like cells in their storage niches. Finally, it proposes strategies to suppress adipogenesis in adipose tissues.

Peanut sprout ethanol extract inhibits the adipocyte proliferation, differentiation, and matrix metalloproteinases activities in mouse fibroblast 3T3-L1 preadipocytes

3T3-L1 preadipocyte were differentiated to adipocytes, and then treated with 0, 10, 20, and 40 µg/mL of peanut sprout ethanol extract (PSEE). The main component of PSEE is resveratrol which contained 5.55 mg/mL of resveratrol. The MTT assay, Oil-Red O staining, glycerol-3-phosphate dehydrogenase (GPDH) activity, and the triglyceride concentration were determined in 3T3-L1 cells. MMP-2 and MMP-9 activities as well as mRNA expressions of C/EBP β and C/EBP α were also investigated. As the concentration of PSEE in adipocytes increased, the cell proliferation was decreased in a dose-dependent manner from 4 days of incubation (P < 0.05). The GDPH activity (P < 0.05) and the triglyceride concentration (P < 0.05) were decreased as the PSEE treatment concentration increased. The mRNA expression of C/EBPβ in 3T3-L1 cells was significantly low in groups of PSEE-treated, compared with control group (P < 0.05). The MMP-9 (P < 0.05) and MMP-2 (P < 0.05) activities were decreased in a dose-dependent manner as the PSEE concentration increased from 20 µg/mL. In conclusion, it was found that PSEE has an effect on restricting proliferation and differentiation of adipocytes.

Tumor necrosis factor-α induces aortic intima-media thickening via perivascular adipose tissue inflammation

BACKGROUND/AIMS

Neointimal thickening results from inflammation in association with vascular smooth muscle cell (VSMC) proliferation. We studied the role of perivascular adipose tissue (PVAT) on VSMC proliferation and intima-media thickening (IMT) in a rodent model of chronic inflammation.

METHODS

The abdominal aorta and surrounding PVAT of tumour necrosis factor (TNF)-α-injected mice were examined 28 days after administration. Plasma and PVAT cytokines were measured with Milliplex™ assays. Inflammatory cells were examined with immunofluorescence. Expression of transforming growth factor (TGF)-β1, matrix metalloproteinase (MMP)-2, MMP-9 and MMP-12 was examined with immunohistochemistry, immunoblotting and zymography. IMT was determined. Cell proliferation and TGF-β1 mRNA levels were examined after treating VSMC with PVAT homogenates ± MMP-2 inhibitors (batimastat, ARP 100 or TIMP-2) and SB-431542, a selective inhibitor of the TGF-β-type 1 receptor.

RESULTS

Significant increases in CD3, CD68, neutrophils, vascular cell adhesion molecule-1 and MMP-2 in PVAT, and TGF-β1 and IMT of the aorta of TNF-α-injected mice were observed. PVAT of TNF-α-injected mice significantly up-regulated TGF-β1 and increased cell proliferation in a dose-dependent manner and was attenuated by SB-431542, batimastat, ARP 100 and TIMP-2.

CONCLUSIONS

Our study shows that chronic PVAT inflammation leads to MMP-mediated increase in TGF-β1 and hence VSMC proliferation.

Adipose tissue plasticity from WAT to BAT and in between

Adipose tissue plays an essential role in regulating energy balance through its metabolic, cellular and endocrine functions. Adipose tissue has been historically classified into anabolic white adipose tissue and catabolic brown adipose tissue. An explosion of new data, however, points to the remarkable heterogeneity among the cells types that can become adipocytes, as well as the inherent metabolic plasticity of mature cells. These data indicate that targeting cellular and metabolic plasticity of adipose tissue might provide new avenues for treatment of obesity-related diseases. This review will discuss the developmental origins of adipose tissue, the cellular complexity of adipose tissues, and the identification of progenitors that contribute to adipogenesis throughout development. We will touch upon the pathological remodeling of adipose tissue and discuss how our understanding of adipose tissue remodeling can uncover new therapeutic targets. This article is part of a Special Issue entitled: Modulation of Adipose Tissue in Health and Disease.

Matrix metalloproteinase inhibition affects adipose tissue mass in obese mice

1. Because the development of adipose tissue involves remodelling of the extracellular matrix (ECM), which requires matrix metalloproteinase (MMP) activity, we examined whether MMP inhibitors may have the potential to affect adipose tissue mass in obese mice. 2. Administration of the relatively gelatinase-specific MMP inhibitor tolylsam ((R)-3-methyl-2-[4-(3-p-tolyl-[1,2,4]oxadiazol-5-yl)-benzenesulphonylamino]-butyric acid; 100 mg/kg per day) for 7 weeks to obese wild-type mice on a high-fat diet resulted in significantly lower bodyweight (P < 0.05), lower subcutaneous (SC) and gonadal (GON) adipose tissue mass (both P < 0.05) and smaller adipocytes in both SC (P < 0.005) and GON (P < 0.0005) adipose tissues. 3. Magnetic resonance imaging confirmed a lower total body fat content in tolylsam-treated mice (P < 0.0005). In addition, tolylsam treatment of wild-type mice was associated with a marked enhancement in metabolic rate. 4. Electron microscopy analysis of tissue sections at the end of the 7 week feeding period revealed significantly higher collagen accumulation in the ECM of SC adipose tissues of tolylsam-treated mice (P < 0.001). 5. Thus, the relatively gelatinase-specific MMP inhibitor tolylsam has the potential to affect fat tissue growth in obese mice.

Resveratrol inhibits the protein expression of transcription factors related adipocyte differentiation and the activity of matrix metalloproteinase in mouse fibroblast 3T3-L1 preadipocytes

This study attempted to investigate the effects of resveratrol on the differentiation of adipocytes. After cells were treated with various concentrations of resveratrol (0, 10, 20, and 40 µmol/L), adipocyte proliferation, the protein expression of transcription factors, and MMPs' activities were determined. Cell proliferation was inhibited more within 4 days of incubation (P < 0.05), and lipid accumulation in adipocyte was significantly inhibited by 93.8%, 92.4% and 91.5%, respectively, after two days of 10, 20, and 40 µmol/L resveratrol treatment (P < 0.05). Six days of incubation with the three resveratrol concentrations caused a significantly decreases of 63%, 59.9%, and 25.1% GPDH activity as a dose-dependent response. The triglyceride concentration also decreased significantly with the increase of resveratrol concentration (P < 0.05). The protein expression of CCAAT/enhancer-binding protein (C/EBPβ) was decreased significantly by 56% and 30% while PPARγ was significantly reduced by 57% and 15% with resveratrol treatments of 20 and 40 µmol/L, respectively (P < 0.05). The protein expression of C/EBPα was decreased by 83%, 74%, and 38% to increased dosage levels, with significance determined for this decrease from 20 µmol/L of resveratrol. The protein expression of fatty acid binding protein (FABP4) was decreased significantly by 88%, 72%, and 46% with the increase of resveratrol concentration. The activity of MMP-2 was decreased significantly by 84%, 70%, and 63% while MMP-9 activity was decreased significantly by 74%, 62%, and 39% with the increased resveratrol concentrations of 10, 20, and 40 µmol/L, respectively (P < 0.05).

Locally applied leptin induces regional aortic wall degeneration preceding aneurysm formation in apolipoprotein E-deficient mice

OBJECTIVE

Leptin promotes atherosclerosis and vessel wall remodeling. As abdominal aortic aneurysm (AAA) formation involves tissue remodeling, we hypothesized that local leptin synthesis initiates and promotes this process.

METHODS AND RESULTS

Human surgical AAA walls were analyzed for antigen and mRNA levels of leptin and leptin receptor, as well as mRNA for matrix metalloproteinases (MMP)-9 and MMP-12. Leptin and leptin receptor antigen were evident in all AAAs, and leptin, MMP-9, and MMP-12 mRNA was increased relative to age-matched nondilated controls. To simulate in vivo local leptin synthesis, ApoE(-/-) mice were subjected to a paravisceral periaortic application of low-dose leptin. Leptin-treated aortas exhibited decreased transforming growth factor-β and increased MMP-9 mRNA levels 5 days after surgery, and leptin receptor mRNA was upregulated by day 28. Serial ultrasonography demonstrated accelerated regional aortic diameter growth after 28 days, correlating with local medial degeneration, increased MMP-9, MMP-12, and periadventitial macrophage clustering. Furthermore, the combination of local periaortic leptin and systemic angiotensin II administration augmented medial MMP-9 synthesis and aortic aneurysm size.

CONCLUSIONS

Leptin is locally synthesized in human AAA wall. Paravisceral aortic leptin in ApoE(-/-) mice induces local medial degeneration and augments angiotensin II-induced AAA, thus suggesting novel mechanistic links between leptin and AAA formation.

Basement membrane collagen type IV expression by human mesenchymal stem cells during adipogenic differentiation

During adipogenic differentiation human mesenchymal stem cells (hMSC) produce collagen type IV. In immunofluorescence staining differentiating hMSCs started to express collagen type IV when Oil Red O-positive fat droplets appeared intracellularly. Quantitative real time-polymerase chain reaction confirmed progressive increase of collagen type IV α1 and α2 mRNA levels over time, 18.6- and 12.2-fold by day 28, respectively, whereas the copy numbers of α3–α6 mRNAs remained rather stable and low. Type IV collagen was in confocal laser scanning microscopy seen around adipocytes, where also laminins and nidogen were found, suggesting pericellular deposition of all key components of the fully developed basement membrane. Immunofluorescence staining of matrix metalloproteinase-2 (MMP-2, 72 kD type IV collagenase, gelatinase A) and MMP-9 (92 kD type IV collagenase, gelatinase B) disclosed only faint staining of MSCs, but MMP-9 was strongly induced during adipogenesis, whereas MSC supernatants disclosed in zymography pro-MMP-2 and faint pro-MMP-9 bands, which increased over time, with partial conversion of pro-MMP-2 to its active 62 kD form. Differentiation was associated with increasing membrane type 1-MMP/MMP-14 and tissue inhibitor of metalloproteinase-2 (TIMP-2) staining, which may enable participation of type IV collagenases in basement membrane remodelling via ternary MT1-MMP/TIMP-2/MMP-2 or −9 complexes, focalizing the fully active enzyme to the cell surface. MMP-9, which increased more in immunofluorescence staining, was perhaps preferentially bound to cell surface and/or remodelling adipocyte basement membrane. These results suggest that upon MSC-adipocyte differentiation collagen type IV synthesis and remodelling become necessary when intracellular accumulation of fat necessitates a dynamically supporting and instructive, partly denatured adipogenic pericellular type IV collagen scaffold.

Ginseng and Its Active Components Ginsenosides Inhibit Adipogenesis in 3T3-L1 Cells by Regulating MMP-2 and MMP-9

The growth and development of adipose tissue are believed to require adipogenesis, angiogenesis, and extracellular matrix remodeling. As our previous study revealed that ginseng reduces adipose tissue mass in part by decreasing matrix metalloproteinase (MMP) activity in obese mice, we hypothesized that adipogenesis can be inhibited by ginseng and its active components ginsenosides (GSs). Treatment of 3T3-L1 adipocytes with Korean red ginseng extract (GE) inhibited lipid accumulation and the expression of adipocyte-specific genes (PPARγ, C/EBPα, aP2, and leptin). GE decreased both the mRNA levels and activity of MMP-2 and MMP-9 in 3T3-L1 cells. These effects were further inhibited by total GSs (TGSs) and individual GSs. TGSs and individual GSs also significantly decreased MMP-2 and MMP-9 reporter gene activities in the presence of phorbol 12-myristate 13-acetate (PMA), the MMP inducer. Among the GSs, Rb1 most effectively inhibited MMP activity. In addition, PMA treatment attenuated the inhibitory actions of GE and GSs on adipogenesis. Moreover, GE and GSs reduced the expression of NF-κB and AP-1, the transcription factors of MMP-2 and MMP-9. These results demonstrate that ginseng, in particular GSs, effectively inhibits adipogenesis and that this process may be mediated in part through the suppression of MMP-2 and MMP-9. Thus, ginseng and GSs likely have therapeutic potential for controlling adipogenesis.

Artemisinic acid is a regulator of adipocyte differentiation and C/EBP δ expression

Adipocyte dysfunction is associated with the development of obesity. In this study, artemisinic acid, which was isolated from Artemisia annua L., inhibited adipogenic differentiation of human adipose tissue-derived mesenchymal stem cells (hAMSCs) and its mechanism of action was determined. The mRNA levels of peroxidase proliferation-activated receptor (PPAR) γ and CCAAT/enhancer binding protein (C/EBP) α, late adipogenic factors, were reduced by artemisinic acid. Moreover, the mRNA levels of the PPAR γ target genes lipoprotein lipase, CD36, adipocyte protein, and liver X receptor were down-regulated by artemisinic acid. Artemisinic acid reduced expression of the C/EBP δ gene without impacting C/EBP β. In addition, attempts to elucidate a possible mechanism underlying the artemisinic acid-mediated effects revealed that reduced expression of the C/EBP δ gene was mediated by inhibiting Jun N-terminal kinase (JNK). Additionally, artemisinic acid also reduced the expression of the adipogenesis-associated genes glucose transporter-4 and vascular endothelial growth factor. In addition to the interference of artemisinic acid with adipogenesis, artemisinic acid significantly attenuated tumor necrosis factor-α-induced secretion of interleukin-6 by undifferentiated hAMSCs, thus influencing insulin resistance and the inflammatory state characterizing obesity. Taken together, these findings indicate that inhibiting adipogenic differentiation of hAMSCs by artemisinic acid occurs primarily through reduced expression of C/EBP δ, which is mediated by the inhibition of JNK and suggest that aremisinic acid may be used as a complementary treatment option for obesity associated with metabolic syndrome.

Inhibition of gelatinase B (matrix metalloprotease-9) activity reduces cellular inflammation and restores function of transplanted pancreatic islets

Islet transplantation provides an approach to compensate for loss of insulin-producing cells in patients with type 1 diabetes. However, the intraportal route of transplantation is associated with instant inflammatory reactions to the graft and subsequent islet destruction as well. Although matrix metalloprotease (MMP)-2 and -9 are involved in both remodeling of extracellular matrix and leukocyte migration, their influence on the outcome of islet transplantation has not been characterized. We observed comparable MMP-2 mRNA expressions in control and transplanted groups of mice, whereas MMP-9 mRNA and protein expression levels increased after islet transplantation. Immunostaining for CD11b (Mac-1)-expressing leukocytes (macrophage, neutrophils) and Ly6G (neutrophils) revealed substantially reduced inflammatory cell migration into islet-transplanted liver in MMP-9 knockout recipients. Moreover, gelatinase inhibition resulted in a significant increase in the insulin content of transplanted pancreatic islets and reduced macrophage and neutrophil influx compared with the control group. These results indicate that the increase of MMP-9 expression and activity after islet transplantation is directly related to enhanced leukocyte migration and that early islet graft survival can be improved by inhibiting MMP-9 (gelatinase B) activity.

Obesity-associated insulin resistance is correlated to adipose tissue vascular endothelial growth factors and metalloproteinase levels

Background

The expansion of adipose tissue is linked to the development of its vasculature, which appears to have the potential to regulate the onset of obesity. However, at present, there are no studies highlighting the relationship between human adipose tissue angiogenesis and obesity-associated insulin resistance (IR).

Results

Our aim was to analyze and compare angiogenic factor expression levels in both subcutaneous (SC) and omentum (OM) adipose tissues from morbidly obese patients (n = 26) with low (OB/L-IR) (healthy obese) and high (OB/H-IR) degrees of IR, and lean controls (n = 17). Another objective was to examine angiogenic factor correlations with obesity and IR.

Here we found that VEGF-A was the isoform with higher expression in both OM and SC adipose tissues, and was up-regulated 3-fold, together with MMP9 in OB/L-IR as compared to leans. This up-regulation decreased by 23% in OB/-H-IR compared to OB/L-IR. On the contrary, VEGF-B, VEGF-C and VEGF-D, together with MMP15 was down-regulated in both OB/H-IR and OB/L-IR compared to lean patients. Moreover, MMP9 correlated positively and VEGF-C, VEGF-D and MMP15 correlated negatively with HOMA-IR, in both SC and OM.

Conclusion

We hereby propose that the alteration in MMP15, VEGF-B, VEGF-C and VEGF-D gene expression may be caused by one of the relevant adipose tissue processes related to the development of IR, and the up-regulation of VEGF-A in adipose tissue could have a relationship with the prevention of this pathology.

Effect of cosmetic ingredients as anticellulite agents: synergistic action of actives with in vitro and in vivo efficacy

BACKGROUND

The pathophysiology of cellulite involves changes in the subcutaneous adipose layer and the extracellular matrix (ECM) that supports it together with overlying dermal layer. Cellular mechanisms governing cellulite are not fully understood. However, it is accepted that changes include enhanced lipogenesis, decreased lipolysis, and increased lipid storage within the adipocytes as well as changes in the dermal architecture.

AIM

In our studies the ability of cosmetic agents Furcellaria lumbricalis, Fucus vesiculosus, retinoid, conjugated linoleic acid (CLA), and a glaucine mixture to stimulate in vitro 1) lipolysis in human adipocytes and 2) production of pro-collagen I by fibroblasts was investigated in vitro. The ability of these ingredients to improve cellulite condition in vivo was also determined.

PATIENTS/METHODS

Mature adipocytes and 'aged' fibroblasts were used for in vitro studies. The assessment of cellulite in vivo was performed by dermatological grading and ultrasound measurements.

RESULTS

Mature adipocytes treated with combined actives resulted in a significant synergistic increase in free glycerol release. On "aged" fibroblasts, combined treatment of F. vesiculosus and F. lumbricalis stimulated pro-collagen I production. CLA increased pro-collagen I production, but the glaucine mixture had no effect. The clinical study demonstrated a significant improvement in cellulite grading by a dermatologist after 8 and 12 weeks vs. vehicle, and ultrasound imaging showed a significant decrease in fat thickness compared with placebo after 12 weeks.

CONCLUSIONS

Our studies revealed a potent cocktail of ingredients that when combined together can act in vitro to markedly improve lipolysis mechanisms and by way of stimulating pro-collagen I can also have an effect on the surrounding extracellular matrix. The in vitro actions of the ingredients were translated in vivo, where a clinical improvement of cellulite condition was observed.

Tumor cell-educated periprostatic adipose tissue acquires an aggressive cancer-promoting secretory profile

BACKGROUND/AIMS

The microenvironment produces important factors that are crucial to prostate cancer (PCa) progression. However, the extent to which the cancer cells stimulate periprostatic adipose tissue (PPAT) to produce these proteins is largely unknown. Our purpose was to determine whether PCa cell-derived factors influence PPAT metabolic activity.

METHODS

Primary cultures of human PPAT samples from PCa patients (adipose tissue organotypic explants and primary stromal vascular fraction, SVF) were stimulated with conditioned medium (CM) collected from prostate carcinoma (PC3) cells. Cultures without CM were used as control. We used multiplex analysis and ELISA for protein quantification, qPCR to determine mitochondrial DNA (mtDNA) copy number and zymography for matrix metalloproteinase activity, in order to evaluate the response of adipose tissue explants and SVFs to PC3 CM.

RESULTS

Stimulation of PPAT explants with PCa PC3 CM induced adipokines associated with cancer progression (osteopontin, tumoral necrosis factor alpha and interleukin-6) and reduced the expression of the protective adipokine adiponectin. Notably, osteopontin protein expression was 13-fold upregulated. Matrix metalloproteinase 9 activity and mitochondrial DNA copy number were higher after stimulation with cancer CM. Stromovascular cells from PPAT in culture were not influenced by tumor-derived factors.

CONCLUSION

The modulation of adipokine expression by tumor CM indicates the pervasive extent to which tumor cells command PPAT to produce factors favorable to their aggressiveness.