PPARγ Agonist Research Articles

A series of genetically confirmed congenital lipodystrophy and diabetes in adult southern Indian patients.

In this study, we analysed the mutation spectrum in subjects with suspected lipodystrophy using a targeted Next-generation sequencing (NGS) approach. Subjects with suspected lipodystrophy were for screened six genes (AGPAT2, BSCL2, LMNA, PPARG, ZMPSTE24, INSR) and the variants identified were confirmed through Sanger sequencing. The clinical and biochemical parameters were compared among the mutation positive and negative subjects. We identified eight individuals with pathogenic or likely pathogenic mutations, including both homozygous and heterozygous variants. Homozygous variants included AGPAT2(NM_006412.4):c.493-2A>G, AGPAT2(NM_006412.4):c.254_258dup, and BSCL2(NM_001122955.4):c.570del, while heterozygous variants encompassed LMNA(NM_170707.4):c.1444C>T, LMNA(NM_170707.4):c.1456A>G, LMNA(NM_170707.4):c.1445G>A, and PPARG(NM_015869.5):c.949T>C mutations. In this cohort, three subjects were diagnosed with congenital generalized lipodystrophy, while the remaining five had familial partial lipodystrophy. Majority (7/8) of the patients with lipodystrophy had hepatic involvement. Notably, more than half of the subjects (5/8) achieved optimal glycemic control through insulin sensitizers (PPARγ agonist and Metformin). Interestingly, even with a limited gene panel test, mutation-positive individuals exhibited a higher prevalence of typical clinical features and biochemical characteristics associated with lipodystrophy compared to their mutation-negative counterparts. In subjects with lipodystrophy, targeted NGS based screening may establish a genetic diagnosis and aid in family screening and genetic counselling. Knowing the clinical and biochemical features typical to lipodystrophy may help in diagnosis especially in resource limited setting.

Abstract 4136030: Fatty acids disturb cardiomyocyte proliferation by increasing PDK4 and HMGCS2 via PPARδ activation

Background: Almost all cardiac diseases are difficult to cure entirely because cardiomyocytes rarely proliferate to recover cardiac damage. In fact, most mammals have a capacity to regenerate cardiomyocytes immediately after birth. Newborn infant drastically changes cardiac metabolism from glycolysis to oxidative phosphorylation using fatty acids. Previous research revealed that lipid metabolism had a negative influence on cardiomyocyte cell cycle but the mechanism has not been clarified completely. Objective: This study was performed to elucidate the way fatty acid metabolism affects cardiomyocyte proliferation. Methods and results: Isolated and cultured neonatal rat cardiomyocytes (NRCM) were treated with the mixture of palmitic acid, oleic acid, and L-carnitine (FA mix) for 24 hours. Realtime RT-PCR revealed that FA mix increased the mRNA expressions of pyruvate dehydrogenase kinase 4 (PDK4), a fatty acid metabolism regulator, and HMG-CoA synthase 2 (HMGCS2), a ketogenic factor, as well as β-oxidation-related enzymes in dose dependent manner. Simultaneously, the results of immunofluorescent staining showed that FA mix decreased cardiomyocytes expressing Ki67, a cell cycle marker. GW501516, a peroxisome proliferator-activated receptor δ (PPARδ) agonist, also increased fatty acid metabolism factors with the reduction of Ki67 positive cardiomyocytes, whereas fenofibrate, a PPARα agonist, or pioglitazone, a PPARγ agonist, caused little or no change in these phenotypes. Moreover, NRCM pretreated with GSK3787, a PPARδ antagonist, before FA mix stimulation suppressed the upregulations of fatty acid metabolism factors and the reduction of Ki67 expressing cardiomyocytes. Finally, the lentiviral vectors which expressed PDK4 or HMGCS2 were produced to investigate these proteins suppressed NRCM cell cycle directly. Either overexpressing PDK4 or HMGCS2 decreased Ki67 positive NRCM without the upregulation of each other or β-oxidation-related enzymes. Conclusion: Fatty acids disturbed NRCM proliferation by upregulating PDK4 and HMGCS2 through the activation of PPARδ independently from β-oxidation.

Genomic and Bioinformatics Analysis of Familial Partial Lipodystrophy Type 3 Identified in a Patient with Novel PPARγ Mutation and Robust Response to Pioglitazone

Familial partial lipodystrophies (FPLDs) are very rare inherited disorders characterized by partial loss of adipose tissue from the upper and lower extremities. At least seven subtypes of FPLD have been identified and are mostly dominantly inherited. FPLD type 3 is caused by mutations in the PPARγ gene, which encodes for the protein peroxisome proliferator-activated receptor gamma (PPARγ). We identified a Saudi female with PFLD3 presented with partial lipoatrophy, uncontrolled diabetes, severe hypertriglyceridemia, and recurrent pancreatitis. The clinical and biochemical findings in this proband were described before and after treatment with Pioglitazone in addition to the conventional treatment. DNA extraction and whole exome sequencing (WES) were performed to detect the variant. The mutant gene was subjected to Sanger analysis to confirm the results. We applied five specific computational prediction tools to assess the pathogenicity of variation, namely the MT, DANN, CADD, BayesDel, and fitCons tools. We assessed protein modeling and stability with the AlphaFold-generated structures for both wild-type and mutant proteins. Finally, we conducted molecular docking using the AutoDock Vina virtual docking. Upon whole exome sequencing, a c.1024C>T p.(Gln342Ter) missense mutation was detected in the PPARγ gene associated with FPLD3. This variant is a novel mutation that has not been described in all genome databases. Sanger analysis confirmed the heterogenicity and pathogenicity of this variant. All five computational prediction tools indicate that this variant is considered highly pathogenic. Our patient showed a dramatic response to Pioglitazone, a synthetic PPARγ agonist. From structural modeling, we found that the enhanced binding affinity of the mutant PPARγ protein to Pioglitazone likely improves the activation of PPARγ, enhancing its transcriptional activity and resulting in better clinical outcomes. These findings extend the spectrum of PPARγ mutations responsible for FPLD3 and highlight the potential for personalized treatment strategies based on genetic mutations.

Peroxisome proliferator-activated receptor gamma regulates interleukin-6 induced lipoprotein(a) gene expression in human HepG2 cells

Abstract Background Lipoprotein(a)[Lp(a)] is an independent risk factor for atherosclerotic cardiovascular disease (ASCVD) and outcomes. The LPA gene promoter contains an interleukin 6 (IL-6) responsive binding site. IL-6 is a pro-inflammatory cytokine and data from patients with inflammatory diseases indicate an impact of the inflammatory milieu on LPA gene regulation and Lp(a) production. In a clinical study, the peroxisome proliferator-activated receptor gamma (PPARγ) agonist pioglitazone was associated with decreased Lp(a) levels. Publicly accessible ChIP-sequencing of human hepatocytes and measures of Lp(a) production by HepG2 cells provide an opportunity to explore PPARγ regulation of hepatic Lp(a) production. Purpose To investigate the role of PPARγ as a regulator of hepatic Lp(a) production. Methods Public ChIP-sequencing of human hepatocytes was analyzed. Commercially available HepG2 cells were incubated with one of the following: (1) scrambled small interfering RNA (siRNA) alone (control); (2) IL-6 (20ng/mL) and scrambled siRNA ; (3) IL-6 and PPARγ siRNA ; and (4) IL-6 and pioglitazone (25uM). LPA transcription was measured using the quantitative polymerase chain reaction. Results Analysis of the ChIP-sequencing data demonstrated that the LPA locus variant rs56393506, which is associated with increased Lp(a) levels and ASCVD risk in the general population, was within the location of the PPARγ binding site in the LPA promoter (Figure 1). IL-6 significantly increased LPA transcription in the HepG2 cells, compared to control (1.65±0.44 vs. 0.66±0.45, p=0.0027). In the presence of siRNA-mediated knock-down of PPARγ (58±17% PPARγ reduction, p<0.0001 vs. scrambled control), the effect of IL-6 on LPA transcription was significantly amplified (6.78±2.4 vs. 1.65±0.44, p=0.0009). IL-6 did not increase LPA transcription in the presence of the PPARγ agonist pioglitazone compared to control (0.16±0.03 vs. 0.66+0.45, p=0.11, Figure 2). Conclusion PPARγ is a negative regulator of IL-6 induced hepatic Lp(a) production and may represent a new therapeutic target in patients with inflammatory conditions.Figure 1Figure 2

Agonists of the nuclear receptor PPARγ can produce biased signaling.

Biased signaling and ligand bias, often termed functional selectivity or selective nuclear receptor modulation, have been reported for nuclear receptor partial agonists over the past 20 years. Whether signaling differences produced by partial agonists result from less intense modulation, off-target effects, or biased signaling remains unclear. A commonly postulated mechanism for biased signaling is coactivator favoritism, where agonists induce different coactivator recruitment profiles. We find that both GW1929 (full agonist) and MRL24 (partial agonist) favor recruitment of 100-300 residue regions from S-motif coactivators compared to a reference full agonist (rosiglitazone), yielding 95% bias value confidence intervals of 0.05-0.17 and 0.29-0.38 respectively. Calculations based on these data indicate that GW1929 and MRL24 would induce 30-60% higher S-motif coactivator occupancy at the receptor compared to rosiglitazone. We compare the transcriptional effects of these same three ligands on human adipocytes using RNA sequencing and exploratory KEGG pathway analysis. Only 50% (rosiglitazone) and 77% (GW1929) of all gene expression changes are shared between these full agonists after 3 hours of exposure. After 24 hours of exposure, 13/98 KEGG pathways appear more intensely modulated by rosiglitazone than GW1929 (e.g., 95% CI of bias in the regulation of lipolysis in adipocytes pathway is 0.03-0.09), despite similar signaling for the remaining 85 affected pathways. Similarly, rosiglitazone has an unusually large effect on several lipid metabolism-related pathways compared to the partial agonist MRL24. These data indicate that nuclear receptor full and partial agonists can induce biased signaling, likely through differences in coactivator recruitment. Significance Statement Many nuclear receptor partial agonists cause fewer adverse effects and similar efficacy compared to full agonists, potentially by inducing biased agonism. Our data support the idea that partial agonists, and a full agonist, of the nuclear receptor Peroxisome proliferator-activated receptor gamma (PPARγ) are biased agonists, causing different signaling by inducing PPARγ to favor different coactivators. These data indicate that biased agonism can occur in nuclear receptors and should be considered in efforts to develop improved nuclear receptor-targeted drugs.

Anaplastic thyroid carcinoma: a genome-based search for new targeted therapy options

Abstract Introduction/Objective Anaplastic thyroid carcinoma (ATC) is a rare, aggressive thyroid cancer. Precision medicine, particularly gene-targeted therapy has emerged as a promising avenue in cancer treatment. However, few targeted therapies have been approved for ATC. Here, we present a genome-based search for new targeted therapy options using next-generation sequencing (NGS) data of 727 ATC cases. Methods/Case Report Deidentified NGS results in 727 ATC cases were obtained from Foundation Medicine. A search of the literature and genomic databases (TCGA, My Cancer Genome, and DGIdb) was performed to analyzed frequency of gene mutations and corresponding gene targeted drugs. Results (if a Case Study enter NA) Remarkably, 99.17% of the 727 ATC cases had at least one targeted drug option available. Among the 254 unique genes identified with pathogenic mutations, 150 (59.06%) were found to have at least 1 corresponding targeted drug. Among the top 35 most frequently mutated genes (frequency > 2.0%), 27 (80.00%) had available targeted therapies. Notably, most drug categories (70.83%) exhibited multi-gene targeting capabilities. The drug categories based on the percentage of genes targeted from highest to lowest are Serine/Threonine and Tryosine kinase inhibitors, therapeutic antibodies, MEK inhibitors, CDK inhibitors, AKT inhibitors, PI3K inhibitors and immunotherapies. There are an additional 16 drug categories that target 1 to 5 of the 35 frequently mutated genes identified. Of particular interest is MTAP, a previously unreported frequently mutated gene which is most often deleted (14.77%). Several drugs are undergoing phase 1 and/or phase 2 clinical trials for MTAP-deleted solid tumors. MTAP loss holds promise for identifying expanding therapeutic options in ATC. Conclusion Our genome-based analysis indicates that 99.17% of the 727 ATC cases have targeted drug options, targeting 59.06% of identified gene mutations. Among the 24 categories of targeted drugs 17 (70.83%) target more than one gene. The 2018 FDA approval of combination BRAF/MEK inhibitor therapy for management of BRAF V600E-positive ATC was a major first step in gene targeted therapies. Besides that, Tyrosine kinase inhibitors, mTOR inhibitor, PPAR-γ agonist, ALK inhibitor, VEGF inhibitor and several combined treatment and immunotherapeutic agents are currently being tested in ATC clinical trials. These promising findings highlight the expanding repertoire of gene-targeted therapy options in ATC and emphasizes the importance of combined strategies and identifying driver mutations.

Computational Drug Design Approaches for the Identification of Novel Antidiabetic Compounds from Natural Resources through Molecular Docking, ADMET, and Toxicological Studies.

Type 2 diabetes mellitus (T2DM) is usually depicted by relative insulin deficiency, raised blood glucose levels, and the predominant risk factor, insulin resistance. Hence, the development of insulin sensitizer drugs targeting PPAR-γ receptors has expanded enormous interest as an attractive choice for T2DM treatment. Thiazolidinediones (TZD) enhance insulin sensitivity either by directly functioning on gene transcription of the PPARγ receptor related to glucose homeostasis or by systemic sensitization of insulin and, therefore, improved hyperglycemia in a wide range of patients. However, severe complications and adverse effects of TZDs necessitate the development of an efficacious and reliable insulin sensitizer from alternative resources. On the contrary, Nature is a rich source of anticipated effective and safer medicine; more than fifty percent of drugs on the market are developed from natural products. Hence, searching for a new PPAR-γ agonist from bioactive secondary compounds of medicinal plants along with greater efficacy and safety is a recognized and consistent tactic for developing novel antidiabetic agents. Pulicaria jaubertii is a fragrant perennial aromatic plant with anti-inflammatory, antidiabetic, antimicrobial, antimalarial, and insecticidal properties. The current study was designed to use a computer-aided drug design to explore the best antidiabetic compounds from P. jaubertii. Herein, the molecular docking study of 80 investigated ligands against the PPAR-γ receptor identifies the highest docking score for five ligands ranging from -8.9 kcal/mol to 8.0 kcal/mol, which is also more significant than the standard drug pioglitazone (-7.7 kcal/mol) determined by the PyRx 8.0 virtual screening software. GLN286, CYS285, SER289, TYR473, MET364, ARG288, ILE341, and LEU333 residues are found to be significant contributors to the non-bonded interaction between ligands and receptors. Molecular electrostatic potential (MEP), DFT, molecular orbital (MO), ADMET, and toxicological analyses were performed on the selected five high-scored ligands of P. jaubertii. Results documented that all investigated ligands, especially L4, show considerably excellent profiles in molecular docking, MEP, DFT, MO, ADMET, and toxicological predictions, suggesting our drug-designing approaches may contribute to the development of a novel antidiabetic drug for the treatment of T2DM from natural resources.

Neddylation and Its Target Cullin 3 Are Essential for Adipocyte Differentiation.

The ongoing obesity epidemic has raised awareness of the complex physiology of adipose tissue. Abnormal adipocyte differentiation results in the development of systemic metabolic disorders such as insulin resistance and diabetes. The conjugation of NEDD8 (neural precursor cell expressed, developmentally downregulated 8) to target protein, termed neddylation, has been shown to mediate adipogenesis. However, much remains unknown about its role in adipogenesis. Here, we demonstrated that neddylation and its targets, the cullin (CUL) family members, are differentially regulated during mouse and human adipogenesis. Inhibition of neddylation by MLN4924 significantly reduced adipogenesis of 3T3-L1 and human stromal vascular cells. Deletion of NAE1, a subunit of the only NEDD8 E1 enzyme, suppressed neddylation and impaired adipogenesis. Neddylation deficiency did not affect mitotic cell expansion. Instead, it disrupted CREB/CEBPβ/PPARγ signaling, essential for adipogenesis. Interestingly, among the neddylation-targeted CUL family members, deletion of CUL3, but not CUL1, CUL2, or CUL4A, largely replicated the adipogenic defects observed with neddylation deficiency. A PPARγ agonist minimally rescued the adipogenic defects caused by the deletion of NAE1 and CUL3. In conclusion, our study demonstrates that neddylation and its targeted CUL3 are crucial for adipogenesis. These findings provide potential targets for therapeutic intervention in obesity and metabolic disorders.

CAMP driven UCP1 induction in human adipocytes requires ATGL-catalyzed lipolysis

ObjectiveThe uncoupling protein 1 (UCP1) is induced in brown or “beige” adipocytes through catecholamine-induced cAMP signaling, which activates diverse transcription factors. UCP1 expression can also be enhanced by PPARγ agonists such as rosiglitazone (Rsg). However, it is unclear whether this upregulation results from de-novo differentiation of beige adipocytes from progenitor cells, or from the induction of UCP1 in pre-existing adipocytes. To explore this, we employed human adipocytes differentiated from progenitor cells and examined their acute response to Rsg, to the adenylate-cyclase activator forskolin (Fsk), or to both simultaneously. MethodsAdipocytes generated from primary human progenitor cells were differentiated without exposure to PPARγ agonists, and treated for 3, 6 or 78 h to Fsk, to Rsg, or to both simultaneously. Bulk RNASeq, RNAScope, RT-PCR, CRISPR-Cas9 mediated knockout, oxygen consumption and western blotting were used to assess cellular responses. ResultsUCP1 mRNA expression was induced within 3 h of exposure to either Rsg or Fsk, indicating that Rsg’s effect is independent on additional adipocyte differentiation. Although Rsg and Fsk induced distinct overall transcriptional responses, both induced genes associated with calcium metabolism, lipid droplet assembly, and mitochondrial remodeling, denoting core features of human adipocyte beiging. Unexpectedly, we found that Fsk-induced UCP1 expression was reduced by approximately 80% following CRISPR-Cas9-mediated knockout of PNPLA2, the gene encoding the triglyceride lipase ATGL. As anticipated, ATGL knockout suppressed lipolysis; however, the associated suppression of UCP1 induction indicates that maximal cAMP-mediated UCP1 induction requires products of ATGL-catalyzed lipolysis. Supporting this, we observed that the reduction in Fsk-stimulated UCP1 induction caused by ATGL knockout was reversed by Rsg, implying that the role of lipolysis in this process is to generate natural PPARγ agonists. ConclusionsUCP1 transcription is known to be stimulated by transcription factors activated downstream of cAMP-dependent protein kinases. Here we demonstrate that UCP1 transcription can also be acutely induced through PPARγ-activation. Moreover, both pathways are activated in human adipocytes in response to cAMP, synergistically inducing UCP1 expression. The stimulation of PPARγ in response to cAMP may result from the production of natural PPARγ activating ligands through ATGL-mediated lipolysis.

Bioactive constituents from Clerodendrum trichotomum and their α-glucosidase inhibitory and PPAR-γ agonist activities

Three new neoclerodane diterpenoids (1–3), two new steroids (4–5), one new monoterpene (6), one new derivative of benzaldehyde (7) and one new iridoid glycoside (8), along with 19 known phenolic compounds, were isolated from Clerodendrum trichotomum. Their structures were established by a combination of detailed spectroscopic analyses (1D and 2D NMR) and high resolution electrospray ionization mass spectroscopy (HRESIMS). The isolated compounds were screened on α-glucosidase inhibitory and the peroxisome proliferator-activated receptor gamma (PPAR-γ) agonist activities, and the results showed that three phenylethanoid glycosides, verbascoside (9), leucosceptoside a (10), and isoacteoside (13), and two flavonoids, apigenin (22) and luteolin (26) showed potent inhibitory effects against α-glucosidase, with IC50 values in the range from 15 to 700 μM. In addition, four flavonoids apigenin 7-O-β-D-glucuronide (19), apigenin (22), luteolin (26), and quercetin (27) exhibited significant PPAR-γ agonistic activities with EC50 values in the range 2.3–24.9 μM.

Cytarabine chemotherapy induces meibomian gland dysfunction

PurposeCytarabine (Ara-C) chemotherapy causes symptoms resembling meibomian gland dysfunction (MGD), suggesting potential associations between Ara-C and MGD. In this study, the pathological effects of Ara-C on MGD were investigated in a rodent model. MethodsMice received Ara-C with or without rosiglitazone (PPARγ agonist) for 7 consecutive days. Slit-lamp biomicroscope was used for ocular examinations. Immunofluorescence detected acinar cell proliferation, differentiation, and ductal keratinization in the meibomian gland (MG). Lipid accumulation was evaluated by Oil Red O and LipidTox staining. Lipogenic status, FoxO1/FoxO3a cellular localization, and oxidative stress were visualized via immunohistochemistry. Western blotting assessed relative protein expression and AKT/FoxO1/FoxO3a pathway phosphorylation. ResultsAra-C (50 mg/kg) did not affect mouse survival but induced damage to ocular surface microenvironment, including corneal epithelial defects, MG orifice plugging and acinar dropout, and lacrimal gland (LG) dysfunction. Ara-C intervention inhibited proliferation and caused progenitor loss in the MG, as evidenced by reduced PCNA + labeling and P63+/Lrig1+ basal cell numbers. The MG ducts of Ara-C-treated mice exhibited marked dilatation, lipid deposition, and hyperkeratinization (K1/K10 overexpression). Ara-C disrupted MG lipid metabolism by downregulating PPARγ and its downstream lipogenic targets AWAT2/SOAT1/ELOVL4 and upregulating HMGCR. Dephosphorylation of AKT and the subsequent nuclear translocation of FoxO1/FoxO3a contributed to Ara-C-induced PPARγ downregulation. Ara-C triggered oxidative stress with increases in 4-HNE and 8-OHdG and Keap1/Nrf2/HO-1/SOD1 axis dysregulation. Rosiglitazone treatment ameliorated MGD-associated pathological manifestations, LG function, MG lipid metabolism, and oxidative stress in Ara-C-exposed mice. ConclusionsSystemic Ara-C chemotherapy exerted topical cytotoxic effects on the ocular surface, and PPARγ restoration by rosiglitazone mitigated Ara-C-induced MGD alterations.

Dual PPAR-a/g enhances beta cell identity, preserving islet structure in HF-fed mice.

The pancreas suffers from lipotoxicity, which threatens the survival of pancreatic islets. Dual PPAR-alpha(a)/gamma(g) agonism is a promising method for treating type 2 diabetes. This study evaluated the effects of single PPAR-a and PPAR-g or their combined activation on pancreatic islet remodeling, beta-cell proliferation, identity, and maintenance in an experimental obesity model. Fifty three-month-old mice, randomly divided to receive the control (C) or high-fat (HF) diet for ten weeks, were then redivided for a four-week treatment: C, HF, HF-a (received the PPAR-a agonist), HF-g (PPAR-g agonist pioglitazone), and HF-d (PPAR-a/g agonists). The HF group was overweight, had oral glucose intolerance, showed a proinflammatory adipokine profile, exhibited increased alpha and beta cell masses, and islet gene expression compatible with compromised beta cell proliferation and favored dedifferentiation. All treatments reduced body weight, mitigated oral glucose intolerance, and produced an anti-inflammatory adipokine profile, which rescued islet cytoarchitecture, and beta cell function. Principal component analysis (PCA) revealed a shift in the antiapoptotic gene Bcl2 and beta cell proliferation genes (Pax4 and Neurog3) in HF-a. Conversely, HF-g and HF-d benefited from the upregulation of genes related to beta cell function (Fgf21, Glut2, and Glp1r), identity, and maintenance (Pdx1, Neurod1, Mafa, and Nkx6.1). The HF mice were glucose intolerant, showing islet hypertrophy and low beta cell identity-related genes. In contrast, PPAR activation rescued islet structure, and PCA showed that the PPAR-a/g combination was the most effective treatment because it favored beta cell function, identity, and maintenance-related genes, halting the T2DM spectrum in diet-induced obese mice.

Microbiota-derived PPAR-γ signaling and risk of bacterial enteric infection: insight from thiazolidinedione users in a US population-based study.

The ongoing antimicrobial resistant crisis heralds the need for new therapeutics against enteric infection. In mouse models, colon epithelial peroxisome proliferator-activated receptor-γ (PPAR-γ) signaling limits oxygen and nitrate luminal bioavailability, thereby preventing bacterial pathogen colonization. However, whether this mechanism operates similarly in humans remains uncertain. To investigate, we used the cloud-based TriNetX Analytics Platform which aggregates health records from 117 million patients across 66 US healthcare organizations, to assess the risk of bacterial enteric infection among diabetic patients prescribed thiazolidinediones, a class of PPAR-γ agonists. Among 85,117 thiazolidinedione users, we observed a 22-49% lower risk of bacterial enteric infections compared to users of other anti-diabetes medications. This reduction in risk was consistent across high-risk individuals, regardless of sex or age. Similar results were replicated in high-risk patients when thiazolidinedione users were directly compared to those on DPP-4 inhibitors. These findings support the potential protective role of PPAR-γ signaling against bacterial enteric infection and call for further clinical investigation.

PDCD4 promotes inflammation/fibrosis by activating the PPAR‑γ/NF‑κB pathway in mouse atrial myocytes.

Fibrosis is the basis of structural remodeling in atrial fibrillation (AF), during which inflammation is crucial. Programmed cell death factor 4 (PDCD4) is a newly identified inflammatory gene, with unknown mechanisms of action in AF. The present study aimed to elucidate the effects of PDCD4 on the inflammation and structural remodeling of atrial myocytes. For this purpose, a PDCD4 overexpression plasmid (oePDCD4) and PDCD4 small interfering (si)RNA (siPDCD4) were used to modulate PDCD4 expression in mouse atrial myocytes (HL‑1 cells). The expression of PDCD4 was detected using reverse transcription‑quantitative PCR and western blot analysis. The optimal drug concentrations of peroxisome proliferator‑activated receptor γ (PPARγ) agonist (pioglitazone hydrochloride), NF‑κB inhibitor (CBL0137), PPARγ inhibitor (GW9962) and NF‑κB agonist (betulinic acid) were screened using a Cell Counting Kit‑8 assay. The levels of inflammatory factors were detected using enzyme‑linked immunosorbent assays, the expression levels of fibrosis‑related proteins and NF‑κB subunits were detected using western blot analysis, and the expression of phosphorylated (p‑)p65/p65 was detected using immunofluorescence staining. The results revealed that PDCD4 overexpression increased the levels of fibrotic factors (collagen I, collagen III, fibronectin, α‑smooth muscle actin and matrix metalloproteinase 2), pro‑inflammatory cytokines (IFN‑γ, IL‑6, IL‑17A and TNF‑α) and p‑p65, whereas it reduced the levels of anti‑inflammatory cytokines (IL‑4) in HL‑1 cells. Additionally, treatment with the PPARγ agonist and NF‑κB inhibitor reversed the levels of fibrotic‑, pro‑inflammatory and anti‑inflammatory factors in oePDCD4‑HL‑1 cells. By contrast, PDCD4 silencing exerted the opposite effects on fibrotic factors, pro‑inflammatory cytokines, anti‑inflammatory cytokines and p‑p65. In addition, treatment with the PPARγ inhibitor and NF‑κB agonist reversed the levels of fibrotic‑, pro‑inflammatory and anti‑inflammatory factors in siPDCD4‑HL‑1 cells. In conclusion, the present study demonstrated that PDCD4 may induce inflammation and fibrosis by activating the PPARγ/NF‑κB signaling pathway, thereby promoting the structural remodeling of atrial myocytes in AF.

Flavokawain B is an effective natural peroxisome proliferator-activated receptor γ-selective agonist with a strong glucose-lowering effect

Rosiglitazone, a full PPARγ agonist and a classical insulin sensitizer, was once used as a powerful weapon in the treatment of T2DM. However, its applications have been restricted recently because of its multiple side effects. Here, a natural compound, flavokawain B (FKB), which was screened in our previous experiments, was investigated for its potential as a preferable insulin sensitizer because it has no or few side effects. Using the surface plasmon resonance (SPR) technique, we confirmed that FKB is a natural ligand for PPARγ with high binding affinity. In in vitro experiments, FKB significantly increased 2-NBDG uptake in HepG2 and 3T3-L1 cells, which partially stimulated PPARγ transcriptional activity. Compared with rosiglitazone, FKB had little effect on the adipose differentiation of 3T3-L1 cells, and all of these features suggest that FKB is a selective modulator of PPARγ (SPPARγM). Moreover, FKB increased the mRNA expression levels of most genes related to insulin sensitivity and glucose metabolism but had no obvious effect on those related to adipose differentiation. In vivo experiments confirmed that FKB effectively decreased abnormal fasting blood glucose and postprandial blood glucose levels and reduced glycated hemoglobin levels, similar to rosiglitazone, in HFD-fed/STZ-treated and db/db mice, two T2DM animal models, but did not cause side effects, such as weight gain or liver or kidney damage. Further investigation revealed that FKB could inhibit PPARγ-Ser273 phosphorylation, which is the key mechanism involved in improving insulin resistance. Together, FKB is a well-performing SPPARγM that exerts a powerful glucose-lowering effect without causing the same side effects as rosiglitazone, and it may have great potential for development.

Erythropoietin regulates osteoclast formation via up-regulating PPARγ expression

Erythropoietin (EPO), expressed in red blood progenitor cells, primarily regulates erythropoiesis by binding to its receptor. Besides anemia, recent studies have identified new therapeutic indications for EPO that are not connected to red blood cell formation. Elevated EPO levels harm bone homeostasis in adult organisms and are associated with increased osteoclast; however, the underlying molecular mechanisms remain unclear. This study demonstrated that EPO enhanced osteoclast differentiation and bone resorption in vitro. We showed that EPO promoted osteoclast formation by up-regulating PPARγ expression through activating the Jak2/ERK signaling pathway. Consistently, PPARγ antagonists rescued the hyperactivation of osteoclasts due to EPO, while PPARγ agonists reversed the EMP9-mediated decrease in osteoclast differentiation. Further, exposing female mice to EPO for two months led to a decrease in bone mass and increased osteoclast numbers. The present results suggested that EPO promotes osteoclastogenesis by regulating the Jak2/ERK/ PPARγ signaling pathway. From a clinical perspective, the risk of compromised bone health should be considered when using EPO to treat anemia in post-operative patients with intertrochanteric fractures of the femur, as it could significantly impact the patient’s recovery and quality of life.

Peroxisome Proliferator-Activated Receptor Gamma Regulates Interleukin-6-Induced Lipoprotein (a) Gene Expression in Human HepG2 Cells.

Lipoprotein(a) [Lp(a)] is a risk factor for coronary disease. Although levels are primarily genetically determined, data from patients with inflammatory diseases indicate that the inflammatory milieu is associated with increased Lp(a) levels. Lp(a) is synthesized in the liver and the LPA gene promoter contains an interleukin-6 (IL-6) responsive binding site, but the regulatory steps linking inflammation with hepatic Lp(a) synthesis are not well clarified. We explored the interplay between IL-6, peroxisome proliferator-activated receptor gamma (PPARγ), and Lp(a) synthesis in HepG2 cells. Through genetic mapping, a regulatory variant within the LPA promoter overlapping with a PPARγ binding site was identified. In in vitro experiments, IL-6-mediated LPA gene transcription was heightened with PPARγ knock-down and suppressed with pioglitazone, a PPARγ agonist. These results demonstrate an important role of PPARγ as a negative regulator of IL-6 induced hepatic Lp(a) production and may represent a new therapeutic target for patients with inflammatory conditions characterized by elevated Lp(a).

Cinobufagin inhibits M2‑like tumor‑associated macrophage polarization to attenuate the invasion and migration of lung cancer cells.

Macrophages have crucial roles in immune responses and tumor progression, exhibiting diverse phenotypes based on environmental cues. In the present study, the impact of cinobufagin (CB) on macrophage polarization and the consequences on tumor‑associated behaviors were investigated. Morphological transformations of THP‑1 cells into M0, M1 and M2 macrophages were observed, including distinct changes in the size, shape and adherence properties of these cells. CB treatment inhibited the viability of A549 and LLC cells in a concentration‑dependent manner, with an IC50 of 28.8 and 30.12 ng/ml, respectively. CB at concentrations of <30 ng/ml had no impact on the viability of M0 macrophages and lung epithelial (BEAS‑2B) cells. CB influenced the expression of macrophage surface markers, reducing CD206 positivity in M2 macrophages without affecting CD86 expression in M1 macrophages. CB also altered certain expression profiles at the mRNA level, notably downregulating macrophage receptor with collagenous structure (MARCO) expression in M2 macrophages and upregulating tumor necrosis factor‑α and interleukin‑1β in both M0 and M1 macrophages. Furthermore, ELISA analyses revealed that CB increased the levels of pro‑inflammatory cytokines in M1 macrophages and reduced the levels of anti‑inflammatory factors in M2 macrophages. CB treatment also attenuated the migration and invasion capacities of A549 and LLC cells stimulated by M2 macrophage‑conditioned medium. Additionally, CB modulated peroxisome proliferator‑activated receptor γ (PPARγ) and MARCO expression in M2 macrophages and epithelial‑mesenchymal transition in A549 cells, which was partially reversed by rosiglitazone, a PPARγ agonist. Finally, CB and cisplatin treatments hindered tumor growth in vivo, with distinct impacts on animal body weight and macrophage marker expression in tumor tissues. In conclusion, the results of the present study demonstrated that CB exerted complex regulatory effects on macrophage polarization and tumor progression, suggesting its potential as a modulator of the tumor microenvironment and a therapeutic for cancer treatment.

Impact of Sex on the Therapeutic Efficacy of Rosiglitazone in Modulating White Adipose Tissue Function and Insulin Sensitivity.

Obesity and type 2 diabetes mellitus are global public health issues. Although males show higher obesity and insulin resistance prevalence, current treatments often neglect sex-specific differences. White adipose tissue (WAT) is crucial in preventing lipotoxicity and inflammation and has become a key therapeutic target. Rosiglitazone (RSG), a potent PPARγ agonist, promotes healthy WAT growth and mitochondrial function through MitoNEET modulation. Recent RSG-based strategies specifically target white adipocytes, avoiding side effects. Our aim was to investigate whether sex-specific differences in the insulin-sensitizing effects of RSG exist on WAT during obesity and inflammation. We used Wistar rats of both sexes fed a high-fat diet (HFD, 22.5% fat content) for 16 weeks. Two weeks before sacrifice, a group of HFD-fed rats received RSG treatment (4 mg/kg of body weight per day) within the diet. HFD male rats showed greater insulin resistance, inflammation, mitochondrial dysfunction, and dyslipidemia than females. RSG had more pronounced effects in males, significantly improving insulin sensitivity, fat storage, mitochondrial function, and lipid handling in WAT while reducing ectopic fat deposition and enhancing adiponectin signaling in the liver. Our study suggests a significant sexual dimorphism in the anti-diabetic effects of RSG on WAT, correlating with the severity of metabolic dysfunction.

"Emerging clinical approaches in diabetic cardiomyopathy: insights from clinical trials and future directions".

We aim to explore the potential of diverse treatments, including perhexiline, calcium channel blockers, anti-hypertensives, PDE5 inhibitors, anti-anginal drugs, aldose reductase inhibitors, and SGLT-2 inhibitors, supported by clinical evidence. Additionally, this review seeks to identify novel therapeutic targets and future avenues for improving cardiovascular outcomes in diabetic populations. We performed a comprehensive literature review of English-language studies across multiple electronic databases, such as PubMed, ScienceDirect, Scopus, and Google Scholar, focusing on clinical trials. The search utilized keywords including 'Anti-hyperglycaemic drug,' 'Diabetic cardiomyopathy,' 'DPP-4 inhibitors,' 'GLP-1 receptor agonists,' 'Heart failure,' and 'SGLT-2 inhibitors.' We assessed clinical investigations in the treatment of cardiomyopathy and diabetes mellitus (DM) that are enhancing our understanding through trials evaluating the Polypill, Perhexiline, Eplerenone, IMB-1018972, AT-001, tadalafil, and dapagliflozin inhibitors. The development of new targeted interventions is of paramount importance due to the overlooked early symptoms, the complexity of the cellular and molecular pathways involved, and the absence of effective drug therapies. Pharmacological treatments like GLP-1 agonists, SGLT-2 inhibitors, NHE-1, NHE-3, and PPAR-γ agonists show promise for treating DCM. These treatments improve myocardial glucose absorption, address dysregulated glucose and lipid metabolism, and lower heart failure and cardiovascular events. Further research is needed to confirm effectiveness and safety.