CMHX008, a PPARγ partial agonist, enhances insulin sensitivity with minor influences on bone loss

The sacroiliac joint: An original and highly sensitive tool to highlight altered bone phenotype in murine models of skeletal disorders

Bone disorders may affect the skeleton in different ways, some bones being very impaired and others less severely. In translational studies using murine models of human skeletal diseases, the bone phenotype is mainly evaluated at the distal femur or proximal tibia. The sacroiliac joint (SIJ), which connects the spine to the pelvis, is involved in the balanced transfer of mechanical energy from the lumbar spine to the lower extremities. Because of its role in biomechanical stress, the SIJ is a region of particular interest in various bone diseases. Here we aimed to characterize the SIJ in several murine models to develop a highly reliable tool for studying skeletal disorders. We performed a 12-month in vivo micro-computed tomography (micro-CT) follow-up to characterize the SIJ in wild-type (WT) C57BL/J6 mice and compared the bone microarchitecture of the SIJ and the distal femur at 3 months by micro-CT and histology. To test the sensitivity of our methodology, the SIJ and distal femur were evaluated at 3 and 6 months, in 2 murine models of skeletal disorder, X-linked hypophosphatemia (Hyp mice) and HLA-B27 transgenic mice and compared to WT mice. A multimodal analysis was performed, using a combination of microCT and histological analysis. With the Hyp model, the SIJ displayed more bone microarchitecture alterations than the distal femur. Hyp mice showed a significant reduction in trabecular bone at both the distal femur and sacral slope as compared with WT mice, with a significant positive correlation between trabecular bone parameters of the distal femur and sacral side of the SIJ. Furthermore, trabecular bone parameters (Bone Volume/Total Volume (BV/TV), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), trabecular number (Tb.N), trabecular pattern factor (Tb.Pf)) were significantly increased compared to femoral parameters at the SIJ. The sacral articular cortical bone, which is indicative of osteoarticular lesions, was altered in Hyp mice. Interestingly, in accordance to previous studies, HLA-B27 transgenic mice did not show any osteoarticular lesions as compared with WT mice. Cortical bone parameters (thickness, porosity), as well as scoring performed with double blinding, did not show difference between the 2 genotypes. The characterization and evaluation of the SIJ surface appears very sensitive to emphasize alterations of bone and joint. The SIJ may represent a valuable tool to investigate both bone and local osteoarticular alterations in murine models of skeletal disorders and might be a relevant site for assessing the response to treatment of chronic bone diseases.

Synthesis, molecular docking, and in vivo antidiabetic evaluation of new benzylidene-2,4-thiazolidinediones as partial PPAR-γ agonists

Peroxisome proliferator-activated receptor-γ (PPAR-γ) partial agonists or antagonists, also termed as selective PPAR-γ modulators, are more beneficial than full agonists because they can avoid the adverse effects associated with PPAR-γ full agonists, such as weight gain and congestive heart disorders, while retaining the antidiabetic efficiency. In this study, we designed and synthesized new benzylidene-thiazolidine-2,4-diones while keeping the acidic thiazolidinedione (TZD) ring at the center, which is in contrast with the typical pharmacophore of PPAR-γ agonists. Five compounds (5a-e) were designed and synthesized in moderate to good yields and were characterized using spectral techniques. The in vivo antidiabetic efficacy of the synthesized compounds was assessed on streptozotocin-induced diabetic mice using standard protocols, and their effect on weight gain was also studied. Molecular docking and molecular dynamics (MD) simulation studies were performed to investigate the binding interactions of the title compounds with the PPAR-γ receptor and to establish their binding mechanism. Antidiabetic activity results revealed that compounds 5d and 5e possess promising antidiabetic activity comparable with the standard drug rosiglitazone. No compound showed considerable effect on the body weight of animals after 21 days of administration, and the findings showed statistical difference (p < 0.05 to p < 0.0001) among the diabetic control and standard drug rosiglitazone groups. In molecular docking study, compounds 5c and 5d exhibited higher binding energies (- 10.1 and - 10.0 kcal/mol, respectively) than the native ligand, non-thiazolidinedione PPAR-γ partial agonist (nTZDpa) (- 9.8 kcal/mol). MD simulation further authenticated the stability of compound 5c-PPAR-γ complex over the 150 ns duration. The RMSD, RMSF, rGyr, SASA, and binding interactions of compound 5c-PPAR-γ complex were comparable to those of native ligand nTZDpa-PPAR-γ complex, suggesting that the title compounds have the potential to be developed as partial PPAR-γ agonists.

Bavachinin selectively modulates PPAR γ and maintains bone homeostasis in Type 2 Diabetes

Full peroxisome proliferator-activated receptor (PPAR) γ agonists, Thiazolidinediones (TZDs), effectively prevent the process of Type 2 Diabetes Mellitus (T2DM), but their side effects have curtailed use in the clinic, including weight gain and bone loss. Here, we identified that a selective PPAR γ modulator, Bavachinin (BVC), isolated from the seeds of Psoralea Corylifolia L., could potently regulate bone homeostasis. MC3T3-E1 pre-osteoblast cells and C3H10T1/2 mesenchymal stem cells were assessed for osteogenic differentiation activities, and receptor activator of NF-κB ligand (RANKL)-induced RAW 264.7 cells were assessed osteoclasts formation. Leptin receptor-deficient mice and diet-induced obesity mice were applied to evaluate the effect of BVC on bone homeostasis in vivo. Compared to full PPAR γ agonist rosiglitazone, BVC significantly increased the osteogenesis differentiation activities under normal and high glucose conditions in MC3T3-E1 cells. Moreover, BVC could alleviate osteoclast differentiation in RANKL-induced RAW 264.7 cells. In vivo, synthesized BVC prodrug (BN) has been applied to improve water solubility, increase the extent of oral absorption of BVC and prolong its residence time in blood circulation. BN could prevent weight gain, ameliorate lipid metabolism disorders, improve insulin sensitivity, and maintain bone mass and bone biomechanical properties. BVC, a unique PPAR γ selective modulator, could maintain bone homeostasis, and its prodrug (BN) exhibits insulin sensitizer activity while circumventing the side effects of the TZDs, including bone loss and undesirable weight gain.

AM-879, a PPARy non-agonist and Ser273 phosphorylation blocker, promotes insulin sensitivity without adverse effects in mice

Obesity is one of the main risk factors for type 2 diabetes, and peroxisome proliferator-activated receptor γ (PPARγ) is considered a promising pathway on insulin sensitivity and adipose tissue metabolism. The search for molecules acting as insulin sensitizers have increased, especially for molecules that block PPARγ-Ser273 phosphorylation, without reaching full agonism. We evaluated the in vivo effects of AM-879, a PPARγ non-agonist, and found that AM-879 exerts different effects in mice depending on the dose. At lower doses, this ligand decreased BAT, increased leptin and Crh expression. However, at a higher dose, it promoted improvement on insulin sensitivity, ameliorates expression of metabolism-related genes, decreased the expression of genes related to liver toxicity, maintaining body weight and adipocyte size. These results present a new lead molecule to ameliorates insulin resistance and confirm AM-879 as a PPARγ non-agonist which blocks Ser273 phosphorylation as a good strategy to modulate insulin sensitivity without developing the adverse effects promoted by PPARγ full agonists.

Role of Plant Derived Products Through Exhilarating Peroxisome Proliferator Activated Receptor-γ (ppar-γ) in the Amelioration of Obesity Induced Insulin Resistance

Abstract:

Insulin resistance is an elemental facet of the etiology of diabetes mellitus and the principal relating factor between obesity and diabetes. Oxidative stress, lipotoxicity, inflammation and receptor dysfunction are the underlying determinants of insulin resistance commencement in metabolic illnesses. ppar-γ is a nuclear transcription factor whose activation or inhibition directly influences insulin resistance and controls glucose and lipid homeostasis by modulating gene expression. Synthetic ligands of ppar-γ are therapeutically employed to counter the hyper-glycaemia associated with obesity and type 2 diabetes, but they possess severe side effects. In the modern era, bioactive phytochemicals have been employed in the drug development process and a considerable investigation has recently been initiated to analyze the ppar-γ activating ability of diverse phytochemicals. In this review, we outlined the role of phytochemicals in insulin resistance treatment through ppar-γ activation.

Ectopic Overexpression of PPARγ2 in the Heart Determines Differences in Hypertrophic Cardiomyopathy After Treatment With Different Thiazolidinediones in a Mouse Model of Diabetes

The clinical controversy of rosiglitazone as a hypoglycemic agent is potentially associated with heart failure, mainly due to its potent activation of peroxisome proliferator-activated receptor γ (PPARγ). PPARγ partial agonists showed superior pharmacological profiles to rosiglitazone. This study compared differences in cardiac morphology and function of the PPARγ partial agonist CMHX008 with rosiglitazone. High-fat diet (HFD) induced obese mice, ob/ob mice and cardiomyocytes overexpressing PPARγ2 were treated with CMHX008 or rosiglitazone. Heart function, myocardial morphology, and hypertrophy-related gene expression were examined. Clinical information from patients with type 2 diabetes mellitus (T2DM) who had taken rosiglitazone and undergone Doppler echocardiography was collected. HFD and ob/ob mice significantly developed cardiac contractile dysfunction, with upregulated PPARγ2 protein levels in heart tissues. Cardiomyocytes of HFD and ob/ob mice were disorderly arranged, the cell areas expanded, and collagen accumulated. In vitro cardiomyocytes overexpressing PPARγ2 displayed obvious structural abnormalities and high mRNA levels of ANP and BNP, critical cardiac hypertrophy-related genes. HFD-fed mice treated with rosiglitazone or CMHX008 had significantly improved cardiac function, but rosiglitazone induced higher expression of ANP and βMHC and hypertrophic cardiomyopathy, while CMHX008 did not. Patients with T2DM taking rosiglitazone exhibited increased thickness of the posterior wall and the ventricular septum, suggesting cardiac hypertrophy. Our findings show that diabetic cardiomyopathy was associated with ectopic overexpression of PPARγ2. The full agonist rosiglitazone prevents cardiac dysfunction at the expense of compensatory hypertrophy, while the partial agonist CMHX008 shared a comparable protective effect without altering the structure of cardiomyocytes.

Silencing Smad7 potentiates BMP2-induced chondrogenic differentiation and inhibits endochondral ossification in human synovial-derived mesenchymal stromal cells

BACKGROUND

Bone morphogenetic protein 2 (BMP2) is a promising chondrogenic growth factor for cartilage tissue-engineering, but it also induces robust endochondral ossification. Human synovial-derived mesenchymal stromal cells (hSMSCs) have attracted great interest due to their poor potential for differentiation into osteogenic lineages. Smad7 plays a significant in the endochondral ossification. In this study, we explored a new method to amplify the BMP2-induced chondrogenic differentiation of hSMSCs by downregulating Smad7 and applying a cellular scaffold.

METHODS

hSMSCs were isolated from human knee joint synovium from 3 donors through adhesion growth. In vitro and in vivo models of the chondrogenic differentiation of hSMSCs were established. Transgenic expression of BMP2 and silencing of Smad7 and Smad7 was achieved by adenoviral vectors. The osteogenic differentiation was detected by alkaline phosphatase staining, alizarin red staining, and RT-PCR analysis of the osteogenic genes RUNX2, Osterix, and Osteocalcin. The chondrogenic differentiation was detected by Alcian blue staining and RT-PCR analysis of the chondrogenic genes SOX9, COL2, and aggrecan. Hypertrophic differentiation was detected by the markers COL10 and MMP13. A subcutaneous stem cell implantation model was established with polyethylene glycol citrate-co-N-isopropylacrylamide (PPCN) scaffolds and athymic nude mice (3/group, 4-6 week-old female) and evaluated by micro-CT, H&E staining, and Alcian blue staining. An immunohistochemistry assay was used to detected COL1 and COL2, and an immunofluorescence assay was used to detect COL10 and MMP13.

RESULTS

These hSMSCs identified by flow cytometry. These hSMSCs exhibited lower osteo-differentiation potential than iMads and C3H10T1/2-cells. When Smad7 was silenced in BMP2-induced hSMSCs, the chondrogenic differentiation genes SOX9, COL2, and aggrecan were enhanced in vitro. Additionally, it silencing Smad7 led to a decrease in the hypertrophic differentiation genes COL10 and MMP13. In subcutaneous stem cell implantation assays, immunofluorescence and immunohistochemical staining demonstrated that silencing Smad7 increased the number of COL2-positive cells and decreased the expression of COL1, COL10, and MMP13.

CONCLUSION

This study suggests that the application of hSMSCs, cell scaffolds, and silencing Smad7 can potentiate BMP2-induced chondrogenic differentiation and inhibit endochondral ossification. Thus, inhibiting the expression of Smad7 in BMP2-induced hSMSC differentiation may be a new strategy for cartilage tissue-engineering.

Anti-Diabetic Effect of Telmisartan Through its Partial PPARγ-Agonistic Activity

Telmisartan is an angiotensin II receptor antagonist, which selectively inhibits the angiotensin II type 1 receptor. Thus, it is widely used for hypertension management. Nowadays, telmisartan's effect on peroxisome proliferator-activated receptors (PPARs) is gaining wider attention. PPARs are ligand-activated transcription factors that belong to the nuclear hormone receptor superfamily. Telmisartan is reported to have a partial PPARγ-agonistic effect while avoiding the safety concerns found with full PPARγ agonists (thiazolidinediones). Telmisartan could be an alternative treatment option, with dual benefit for diabetes mellitus (DM) and hypertension. This review summarizes the anti-diabetic activity of telmisartan via its partial PPARγ-agonistic activity.

Peroxisome Proliferator-Activated Receptors and Caloric Restriction-Common Pathways Affecting Metabolism, Health, and Longevity

Caloric restriction (CR) is a traditional but scientifically verified approach to promoting health and increasing lifespan. CR exerts its effects through multiple molecular pathways that trigger major metabolic adaptations. It influences key nutrient and energy-sensing pathways including mammalian target of rapamycin, Sirtuin 1, AMP-activated protein kinase, and insulin signaling, ultimately resulting in reductions in basic metabolic rate, inflammation, and oxidative stress, as well as increased autophagy and mitochondrial efficiency. CR shares multiple overlapping pathways with peroxisome proliferator-activated receptors (PPARs), particularly in energy metabolism and inflammation. Consequently, several lines of evidence suggest that PPARs might be indispensable for beneficial outcomes related to CR. In this review, we present the available evidence for the interconnection between CR and PPARs, highlighting their shared pathways and analyzing their interaction. We also discuss the possible contributions of PPARs to the effects of CR on whole organism outcomes.

Marrow Adipocytes: Origin, Structure, and Function

The skeleton harbors an array of lineage cells that have an essential role in whole body homeostasis. Adipocytes start the colonization of marrow space early in postnatal life, expanding progressively and influencing other components of the bone marrow through paracrine signaling. In this unique, closed, and hypoxic environment close to the endosteal surface and adjacent to the microvascular space the marrow adipocyte can store or provide energy, secrete adipokines, and target neighboring bone cells. Adipocyte progenitors can also migrate from the bone marrow to populate white adipose tissue, a process that accelerates during weight gain. The marrow adipocyte also has an endocrine role in whole body homeostasis through its varied secretome that targets distant adipose depots, skeletal muscle, and the nervous system. Further insights into the biology of this unique and versatile cell will undoubtedly lead to novel therapeutic approaches to metabolic and age-related disorders such as osteoporosis and diabetes mellitus.