Effect of gelatinase inhibition on adipogenesis and adipose tissue development

Adipocyte-secreted microvesicle-derived miR-148a regulates adipogenic and osteogenic differentiation by targeting Wnt5a/Ror2 pathway

AIMS

Adipocyte-secreted microvesicles (MVs)-derived microRNAs (miRNAs) are relevant to adipogenic and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) in osteonecrosis of the femoral head (ONFH). Our aims are to investigate the mechanism of adipocyte-derived MVs-miR-148a in ONFH.

MATERIALS AND METHODS

Adipocyte-derived MVs were identified via transmission electron microscopy and specific markers expression. The adipogenic and osteogenic differentiation were investigated by Oil-Red O staining, alkaline phosphatase (ALP) activity, Alizarin Red S (ARS) staining and osteogenic or adipogenic factors levels. Genes and proteins expression were detected by using quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting. The relationship between miR-148a and Wnt5a was tested via dual-luciferase reporter analysis. The adipogenic differentiation and osteogenic differentiation in methylprednisolone (MPS)-induced ONFH rat model were assessed via hematoxylin-eosin (HE) staining, and immunohistochemical staining of collagen I (COL I).

KEY FINDINGS

Adipocyte-derived MVs promoted adipogenic differentiation via increasing Oil-Red O staining positive cells, adiponectin (Adipoq), acid-binding protein 2 (aP2) and peroxisome proliferator-activated receptor γ (PPAR-γ) levels, and repressed osteogenic differentiation of BMSCs via decreasing ARS staining positive cells, ALP, Runt-related transcription factor 2 (RUNX2) and osteocalcin (OCN) levels. MiR-148a was present in adipocyte-derived MVs, and miR-148a knockdown inhibited adipogenic differentiation and promoted osteogenic differentiation. Furthermore, Wnt5a expression was regulated by miR-148a. MiR-148a overexpression facilitated adipogenic differentiation and suppressed osteogenic differentiation via regulating the Wnt5a/Ror2 pathway. Adipocyte-derived MVs promoted adipogenic differentiation and inhibited osteogenic differentiation in MPS-induced ONFH rat model.

SIGNIFICANCE

Adipocyte-derived MVs-miR-148a promoted adipogenic differentiation and suppressed osteogenic differentiation via targeting the Wnt5a/Ror2 pathway.

Does butein affect adipogenesis?

Butein is a plant flavonoid chalcone, with presumed anti-adipogenic properties. It was reported to impair preadipocyte differentiation, limit adipose tissue (AT) development and enhance white AT browning in rodents. In this study, we investigated the hypothesis that these effects of butein may occur via reduction of ADAMTS5 (A Disintegrin And Metalloproteinase with ThromboSpondin motifs 5) expression. Murine 3T3-L1 or 3T3-F442A preadipocytes were differentiated into mature adipocytes in the presence of butein or vehicle. At regular time intervals RNA was collected for gene expression studies. Male hemizygous mice for Tg(Ucp1-luc2,-tdTomato)1Kajim (ThermoMouse) were exposed to butein or vehicle, after which ATs were analyzed for Adamts5 and uncoupling protein-1 (Ucp-1) mRNA level changes. During preadipocyte differentiation, butein (25 – 50 mM) did not affect Adamts5 or Ucp-1 expression. Oil Red O analysis and monitoring of differentiation markers failed to demonstrate effects of butein on the differentiation extent. Furthermore, butein administration to the ThermoMouse (10 or 20 mg/kg, 4 days) or to the C57BL6/Rj mice (20 mg/kg, 4 weeks) did not enhance Adamts5 or Ucp-1 expression. Thus, we could not demonstrate marked effects of butein on the preadipocyte differentiation extent or AT development and browning, nor on Adamts5 or Ucp-1 gene expression during these processes.

MMP-2: is too low as bad as too high in the cardiovascular system?

Matrix metalloproteinase (MMP)-2 cleaves a broad spectrum of substrates, including extracellular matrix components (responsible for normal tissue remodeling) and cytokines (modulators of the inflammatory response to physiological insults such as tissue damage). MMP-2 expression is elevated in many cardiovascular pathologies (e.g., myocardial infarction, hypertensive heart disease) where tissue remodeling and inflammatory responses are perturbed. Thus, it has generally been assumed that blockade of MMP-2 activity will yield therapeutic effects. Here, we provide a counterargument to this dogma based on 1) preclinical studies on Mmp2-null ( Mmp2−/−) mice and 2) clinical studies on patients with inactivating MMP2 gene mutations. Furthermore, we put forward the hypothesis that, when MMP-2 activity falls below baseline, the bioavailability of proinflammatory cytokines normally cleaved and inactivated by MMP-2 increases, leading to the production of cytokines and cardiac secretion of phospholipase A2activity into the circulation, which stimulate systemic inflammation that perturbs lipid metabolism in target organs. Finally, we suggest that insufficient understanding of the consequences of MMP-2 deficiency remains a major factor in the failure of MMP-2 inhibitor-based therapeutic approaches. This paucity of knowledge precludes our ability to effectively intervene in cardiovascular and noncardiovascular pathologies at the level of MMP-2.

Efficacy of Fenugreek-based bionanocomposite on renal dysfunction and endogenous intoxication in high-calorie diet-induced obesity rat model-comparative study

BACKGROUND

Worldwide obesity spread is a global health problem and needs to be further studied. Co-morbidities of obesity include insulin resistance, diabetes mellitus type 2, and dyslipidemia, which are the most frequent contributing factors for metabolic syndrome (MetS), as well as non-alcoholic fatty liver disease and chronic kidney disease. The aim was to study renal function and endogenous intoxication panel on high-calorie diet-induced obesity rat model and perform comparative study of the treatment efficacy of Fenugreek-based bionanocomposite vs antiobesogenic drugs (Orlistat).

MATERIALS

We included 60 male rats and equally divided them to 6 groups of 10 animals in each group: the experimental groups were firstly assigned as controls and high caloric diet (HCD)-fed groups, and each group further was subdivided to remain untreated, Fenugreek bionanocomposite (BNC)-treated, and Orlistat-treated. Normal control rats (groups 1, 2, 3) were fed by a standard chow, while the others (groups 4, 5, 6) were fed with HCD ad libitum during 98 days. From days 77 to 98, groups 2 and 5 were treated with BNC based on Fenugreek (150 mg/kg body weight, orally) and groups 3 and 6 were treated with antiobesogenic drug Orlistat (10 mg/kg body weight, orally). Food and water consumptions were measured daily and body weights were measured once a week. On day 99, blood was collected; the creatinine, urea, and uric acid were estimated in serum according to the standard protocols. Levels of low and middle molecules (MMs) were measured; the quantity of oligopeptides was estimated by Bradford method. We performed the liver and kidney ultrasonography in rats.

RESULTS

We revealed an increase in the levels of endogenous intoxication syndrome markers (MM and oligopeptides) in all animals with experimental obesity. Ultrasound data showed injury of the liver and kidneys in obese rats. We observed significant decreasing of MM levels after Orlistat treatment vs controls (p < 0.05). However, this effect was more pronounced in Fenugreek BNC-treated group vs both Orlistat-treated and controls (p < 0.05). Orlistat treatment evoked rising of serum creatinine and oligopeptides in control animals and failed to normalize these markers in experimental group. Fenugreek-based BNC treatment did not evoke signs of kidney failure and changes in the studied indices in control group. We noticed normalization levels of uric acid and urea in the blood under the use of BNC and Orlistat.

CONCLUSION

High-calorie diet-induced obesity evokes endogenous intoxication syndrome and kidney dysfunction in rats. Application of Orlistat- and Fenugreek-based BNC decreases MM content to the normal level. Orlistat induces increasing levels of oligopeptides in both groups, likely due to adverse side effects on renal function and its pro-oxidant activity.

Novel Role for Matrix Metalloproteinase 9 in Modulation of Cholesterol Metabolism

Background

The development of atherosclerosis is strongly linked to disorders of cholesterol metabolism. Matrix metalloproteinases (MMPs) are dysregulated in patients and animal models with atherosclerosis. Whether systemic MMP activity influences cholesterol metabolism is unknown.

Methods and Results

We examined MMP‐9–deficient (Mmp9^−/−) mice and found them to have abnormal lipid gene transcriptional responses to dietary cholesterol supplementation. As opposed to Mmp9^+/+ (wild‐type) mice, Mmp9^−/− mice failed to decrease the hepatic expression of sterol regulatory element binding protein 2 pathway genes, which control hepatic cholesterol biosynthesis and uptake. Furthermore, Mmp9^−/− mice failed to increase the expression of genes encoding the rate‐limiting enzymes in biliary cholesterol excretion (eg, Cyp7a and Cyp27a). In contrast, MMP‐9 deficiency did not impair intestinal cholesterol absorption, as shown by the ¹⁴C‐cholesterol and ³H‐sitostanol absorption assay. Similar to our earlier study on Mmp2^−/− mice, we observed that Mmp9^−/− mice had elevated plasma secreted phospholipase A₂ activity. Pharmacological inhibition of systemic circulating secreted phospholipase A₂ activity (with varespladib) partially normalized the hepatic transcriptional responses to dietary cholesterol in Mmp9^−/− mice. Functional studies with mice deficient in other MMPs suggested an important role for the MMP system, as a whole, in modulation of cholesterol metabolism.

Conclusions

Our results show that MMP‐9 modulates cholesterol metabolism, at least in part, through a novel MMP‐9–plasma secreted phospholipase A₂ axis that affects the hepatic transcriptional responses to dietary cholesterol. Furthermore, the data suggest that dysregulation of the MMP system can result in metabolic disorder, which could lead to atherosclerosis and coronary heart disease.

ADAMTS5 promotes murine adipogenesis and visceral adipose tissue expansion

Enhanced expression of the aggrecanase ADAMTS5 (A Disintegrin And Metalloproteinase with Thrombospondin type 1 motifs; member 5) has been observed in adipose tissue (AT) of obese rodents. Here, we have investigated the role of ADAMTS5 in adipogenesis, AT expansion and associated angiogenesis. In vitro differentiation of precursor cells into mature adipocytes was studied using murine embryonic fibroblasts (MEF) derived from wild-type (Adamts5(+/+)) and ADAMTS5 deficient (Adamts5(-/-)) mice, or 3T3-F442A preadipocytes with stable gene silencing of Adamts5. De novo adipogenesis was monitored by injection of 3T3-F442A cells with or without Adamts5 knockdown in Nude mice. Furthermore, Adamts5(+/+)and Adamts5(-/-) mice were kept on a high-fat diet (HFD) to monitor AT development. Adamts5(-/-) MEF, as well as 3T3-F442A preadipocytes with Adamts5 knockdown, showed significantly reduced differentiation as compared to control cells. In mice, de novo formed fat pads arising from 3T3-F442A cells with Adamts5 knockdown were significantly smaller as compared to controls. After 15 or 25 weeks on HFD, total body weight and subcutaneous AT weight were similar for Adamts5(+/+) and Adamts5(-/-) mice, but visceral/gonadal fat mass was significantly lower for Adamts5(-/-) mice. These data were confirmed by magnetic resonance imaging. In addition, the blood vessel density in adipose tissue was higher for Adamts5(-/-) mice kept on HFD. In conclusion, our data support the concept that ADAMTS5 promotes adipogenesis in vitro and in vivo, as well as development of visceral AT and associated angiogenesis in mice kept on HFD.

Identification of a Novel Heart-Liver Axis: Matrix Metalloproteinase-2 Negatively Regulates Cardiac Secreted Phospholipase A2 to Modulate Lipid Metabolism and Inflammation in the Liver

BACKGROUND

Endocrine functions of the heart have been well established. We investigated the hypothesis that cardiac secretion of a unique phospholipase A2 recently identified by our laboratory (cardiac secreted phospholipase A2 [sPLA2]) establishes a heart-liver endocrine axis that is negatively regulated by matrix metalloproteinase-2 (MMP-2).

METHODS AND RESULTS

In Mmp2(-/-) mice, cardiac (but not hepatic) sPLA2 was elevated, leading to hepatic inflammation, immune cell infiltration, dysregulation of the sterol regulatory element binding protein-2 and liver X receptor-α pathways, abnormal transcriptional responses to dietary cholesterol, and elevated triglycerides in very low-density lipoprotein and in the liver. Expression of monocyte chemoattractant protein-3, a known MMP-2 substrate, was elevated at both mRNA and protein levels in the heart. Functional studies including in vivo antibody neutralization identified cardiac monocyte chemoattractant protein 3 as a possible agonist of cardiac sPLA2 secretion. Conversely, systemic sPLA2 inhibition almost fully normalized the cardiohepatic phenotype without affecting monocyte chemoattractant protein-3. Finally, wild-type mice that received high-performance liquid chromatography-isolated cardiac sPLA2 from Mmp2(-/-) donors developed a cardiohepatic gene expression profile similar to that of Mmp2(-/-) mice.

CONCLUSIONS

These findings identified the novel MMP-2/cardiac sPLA2 pathway that endows the heart with important endocrine functions, including regulation of inflammation and lipid metabolism in the liver. Our findings could also help explain how MMP2 deficiency leads to cardiac problems, inflammation, and metabolic dysregulation in patients.

Emergence of a metalloproteinase / phospholipase A2 axis of systemic inflammation

We review select aspects of the biology of matrix metalloproteinases (MMPs) with a focus on the modulation of inflammatory responses by MMP-2. MMP-2 is a zinc- and calcium-dependent endoprotease with substrates including extracellular matrix proteins, vasoactive peptides and chemokines. Humans and mice with MMP-2 deficiency exhibit a predominantly inflammatory phenotype. Recent research shows that MMP-2 deficient mice display elevated activity of a secreted phospholipase A₂ in the heart. Additionally, MMP-2 deficient mice exhibit abnormally high prostaglandin E₂ levels in various organs (i.e., the heart, brain and liver), signs of inflammation and exacerbated lipopolysaccharide-induced fever. We briefly review the biology of sPLA₂ enzymes to propose the existence of a heart-centric MMP-2/sPLA₂ axis of systemic inflammation. Moreover, we postulate that PLA₂ activation is induced by chemokines, whose ability to signal inflammation is regulated in a tissue-specific fashion by MMPs. Thus, genetic and pharmacologically induced MMP-deficiencies can be expected to perturb PLA₂-mediated inflammatory mechanisms.

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.

Small ubiquitin-like modifier (SUMO) protein-specific protease 1 de-SUMOylates Sharp-1 protein and controls adipocyte differentiation

Adipocyte differentiation is regulated by a transcriptional cascade that mainly includes CCAAT/enhancer-binding protein family members and the nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ). Here we show the defects in adipocyte differentiation as well as PPARγ expression in Senp1(-/-) mouse embryonic fibroblast cells induced by adipogenic stimuli. We further determine that SENP1 is a specific de-SUMOylation protease for Sharp-1, a repressor for PPARγ transcription and adipogenesis. SENP1 enhances adipogenesis through de-SUMOylation of Sharp-1, which then releases Sharp-1 repression of PPARγ expression and adipocyte differentiation. These results reveal SENP1 as a novel regulator in adipogenesis.

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.

Effect of vascular endothelial growth factor receptor 2 antagonism on adiposity in obese mice

Development and maintenance of fat depots require angiogenesis, in which vascular endothelial growth factor (VEGF) and its receptors play a crucial role. We have evaluated the effect of blocking VEGF receptor 2 (VEGF-R2) with a MAB (DC101) on adipose tissue of mice with established obesity. Therefore, obese male wild-type C57B1/6 mice were treated with i.p. injection of DC101 (40 mg/kg body weight, twice weekly during 13 weeks) or of the control antibody 1C8. Treatment with DC101 resulted in a slightly lower body weight but had no effect on subcutaneous (SC) or gonadal (GON) white adipose tissue mass, as monitored by MRI. Histochemical analysis of isolated SC and GON fat pads did not reveal significant effects of DC101 treatment on adipocyte or blood vessel size or density. Plasma levels of the liver enzymes aspartate aminotransferase and alanine aminotransferase as well as liver triglyceride levels were significantly decreased following DC101 treatment. Plasma glucose levels were markedly lower upon DC101 treatment, whereas insulin and adiponectin levels were not affected. Furthermore, Akt phosphorylation in adipose tissues was not affected. Thus, in vivo VEGF-R2 blockade in mice with established nutritionally induced obesity did not significantly affect insulin signaling in adipose tissue or adiposity.

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.

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.