Telmisartan activates endogenous peroxisome proliferator-activated receptor-δ and may have anti-fibrotic effects in human mesangial cells

Identification of Novel Therapeutic Targets for Hypertension

BACKGROUND

Persistently high blood pressure remains the leading risk factor for mortality worldwide. This study aims to identify potential drug targets for hypertension.

METHODS

Mendelian randomization was used to identify therapeutic targets for hypertension. Genome-wide association study summary statistics were obtained from the UK Biobank and FinnGen study. Cis-expression quantitative trait loci from the eQTLGen Consortium served as genetic instruments. Colocalization analysis evaluated the likelihood of shared causal variants between single-nucleotide polymorphisms influencing hypertension and gene expression. Survival analysis of UK Biobank data assessed hypertension and mortality risks across participants with different gene alleles.

RESULTS

Mendelian randomization analysis identified 190 drug targets in the discovery cohort and 65 in the replication cohort after multiple testing correction. Colocalization analysis identified 14 hypertension-related drug targets, including ACE, AIMP1, CDC25A, EHMT2, FES, GPX1, GRK4, HSD3B7, NEK4, PTPN12, SIK2, SLC22A4, SLC2A4, and TNFSF12. Survival analysis revealed individuals with the A allele at rs4308 in the ACE gene had a higher incidence of hypertension, while those with the T allele at rs11242109 in the SLC22A4 gene showed a lower hypertension-specific mortality rate.

CONCLUSIONS

Drug target Mendelian randomization studies offer new directions for hypertension treatment, providing insights into its mechanisms and robust targets for developing antihypertensive drugs.

A Genetics-guided Integrative Framework for Drug Repurposing: Identifying Anti-hypertensive Drug Telmisartan for Type 2 Diabetes

Drug development is a long and costly process, and repurposing existing drugs for use toward a different disease or condition may serve as a cost-effective alternative. As drug targets with genetic support have a doubled success rate, genetics-informed drug repurposing holds promise in translating genetic findings into therapeutics. In this study, we developed a Genetics Informed Network-based Drug Repurposing via in silico Perturbation (GIN-DRIP) framework and applied the framework to repurpose drugs for type-2 diabetes (T2D). In GIN-DRIP for T2D, it integrates multi-level omics data to translate T2D GWAS signals into a genetics-informed network that simultaneously encodes gene importance scores and a directional effect (up/down) of risk genes for T2D; it then bases on the GIN to perform signature matching with drug perturbation experiments to identify drugs that can counteract the effect of T2D risk alleles. With this approach, we identified 3 high-confidence FDA-approved candidate drugs for T2D, and validated telmisartan, an anti-hypertensive drug, in our EHR data with over 3 million patients. We found that telmisartan users were associated with a reduced incidence of T2D compared to users of other anti-hypertensive drugs and non-users, supporting the therapeutic potential of telmisartan for T2D. Our framework can be applied to other diseases for translating GWAS findings to aid drug repurposing for complex diseases.

Pharmacological Utility of PPAR Modulation for Angiogenesis in Cardiovascular Disease

Peroxisome proliferator activated receptors, including PPARα, PPARβ/δ, and PPARγ, are ligand-activated transcription factors belonging to the nuclear receptor superfamily. They play important roles in glucose and lipid metabolism and are also supposed to reduce inflammation and atherosclerosis. All PPARs are involved in angiogenesis, a process critically involved in cardiovascular pathology. Synthetic specific agonists exist for all PPARs. PPARα agonists (fibrates) are used to treat dyslipidemia by decreasing triglyceride and increasing high-density lipoprotein (HDL) levels. PPARγ agonists (thiazolidinediones) are used to treat Type 2 diabetes mellitus by improving insulin sensitivity. PPARα/γ (dual) agonists are supposed to treat both pathological conditions at once. In contrast, PPARβ/δ agonists are not in clinical use. Although activators of PPARs were initially considered to have favorable effects on the risk factors for cardiovascular disease, their cardiovascular safety is controversial. Here, we discuss the implications of PPARs in vascular biology regarding cardiac pathology and focus on the outcomes of clinical studies evaluating their benefits in cardiovascular diseases.

Telmisartan-Induced Cytotoxicity via G2/M Phase Arrest in Renal Cell Carcinoma Cell Lines

Renal cell carcinoma (RCC) is the most common type of kidney cancer. Given that stage IV RCC is intractable, there is a need for a novel treatment strategy. We investigated the antitumor effects of telmisartan (TEL) and their underlying mechanisms in RCC, including their impact on apoptosis, Akt/mammalian target of rapamycin (mTOR) pathways, and the cell cycle using two human RCC cell lines: 786-O and Caki-2. Cell viability was detected via fluorescence-based assays. Cells were stained with Hoechst 33342 to observe chromatin condensation, and Western blotting was performed to analyze protein expression. The cell cycle was assessed using flow cytometry. Invasion and migration assays were performed using 24-well chambers. TEL induced cell death in a dose-dependent manner and increased the percentage of cells with high chromatin condensation and Bax/Bcl-2 ratio in both cell lines. TEL-induced cell death was attenuated by neither peroxisome proliferator-activated receptor-γ nor -δ inhibitors. Although TEL elevated c-Jun N-terminal kinase levels and p38 phosphorylation rates in Caki-2 cells, as well as extracellular signal-regulated kinase phosphorylation rates in 786-O cells, their inhibitors did not suppress TEL-induced cell death. TEL decreased Akt phosphorylation in 786-O cells and mTOR phosphorylation in both cell lines, increased the population of cells in the G₂/M phase, and altered G₂/M-related proteins in both cell lines. TEL moderately suppressed cell invasion and migration in 786-O and Caki-2 cells, respectively, and increased cell invasion in Caki-2 cells, suggesting a potential therapeutic role of TEL in RCC.

PPAR-δ activation reduces cisplatin-induced apoptosis via inhibiting p53/Bax/caspase-3 pathway without modulating autophagy in murine renal proximal tubular cells

BACKGROUND

Cisplatin-induced injury of renal proximal tubular cells results basically from increased apoptosis via mitochondrial damage, and is mitigated by appropriate enhancement of autophagy. Peroxisome proliferator-activated receptor-delta (PPAR-δ) reportedly protects against not only mitochondrial damages but also enhances autophagy. Thus, PPAR-δ may protect against cisplatin-induced kidney injury.

METHODS

We examined the protective effects of PPAR-δ activation on cisplatin-induced cellular injury and their detailed mechanisms in a murine renal proximal tubular (mProx) cell line using GW0742, an authentic PPAR-δ activator. Cisplatin-induced cell damages were evaluated by TUNEL assay and immunoblot analyses for p53, 14-3-3, Bax, Bcl2, cytochrome C, and activated caspases. Autophagy status was examined by immunoblot analyses for p62 and LC3.

RESULTS

GW0742 suppressed cisplatin-induced apoptosis of mProx cells by reducing the activation of caspase-3 via attenuating the phosphorylation of p53 and 14-3-3, mitochondrial Bax accumulation, cytochrome C release from mitochondria to the cytosol and ensuing cytosolic caspase-9 activation. In contrast, GW0742 did not diminish cisplatin-enhanced activation of caspases-8 or -12 as extrinsic or endothelium reticulum apoptotic pathways, respectively. The inhibitory effect of GW0742 on cisplatin-induced caspase-3 activation was significantly diminished by silencing of the PPAR-δ gene expression. GW0742 itself had no influence on starvation-stimulated or cisplatin-induced autophagy in mProx cells, suggesting that the protective effects were not mediated by autophagy modification.

CONCLUSION

Our results indicate that GW0742 may serve as a candidate agent to mitigate cisplatin nephrotoxicity via inhibiting the mitochondrial apoptotic pathway considerably depending on PPAR-δ, without modulating autophagy.

PPARs and Myocardial Infarction

Peroxisome proliferator-activated receptors (PPARs) belong to the nuclear hormone receptor family. They are ligand-activated transcription factors and exist in three different isoforms, PPARα (NR1C1), PPARβ/δ (NR1C2), and PPARγ (NR1C3). PPARs regulate a variety of functions, including glucose and lipid homeostasis, inflammation, and development. They exhibit tissue and cell type-specific expression patterns and functions. Besides the established notion of the therapeutic potential of PPAR agonists for the treatment of glucose and lipid disorders, more recent data propose specific PPAR ligands as potential therapies for cardiovascular diseases. In this review, we focus on the knowledge of PPAR function in myocardial infarction, a severe pathological condition for which therapeutic use of PPAR modulation has been suggested.

Telmisartan alleviates collagen type III glomerulopathy: A case report with literature review

Collagen type III is commonly detected in the renal interstitium and vasculature; however, it is absent in healthy glomeruli. Deposition of collagen type III in the glomerular mesangium and capillary basement membranes may arise in two rare diseases, namely collagen type III glomerulopathy (CG) and nail patella syndrome. CG is a rare glomerular disease with no specific treatment, although supportive measures for control of hypertension and edema may help to relieve symptoms. With progression to end-stage renal disease, patients with CG may come to require dialysis and/or renal transplantation. The present study reported on a 59-year-old male who was diagnosed with CG nephrotic syndrome by immunohistochemical and electron microscopic examination of biopsy material. To the best of our knowledge, this is the first case reported in northeastern China. The angiotensin II blocker telmisartan was successfully used to alleviate renal symptoms and a literature review was performed. The present case supports the use of telmisartan as a first choice of treatment for CG.

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.

AR420626, a selective agonist of GPR41/FFA3, suppresses growth of hepatocellular carcinoma cells by inducing apoptosis via HDAC inhibition

Background

Hepatocellular carcinoma (HCC) is a major cause of cancer death worldwide and establishment of new chemotherapies for HCC is urgently needed. GPR41 [free fatty acid receptor 3 (FFA3)] is a G protein-coupled receptor for short chain fatty acids, including acetate, propionate, and butyrate. In our previous study, we showed that propionate enhances the cytotoxic effect of cisplatin in HCC cells and that this mechanism is dependent on inhibition of histone deacetylases (HDACs) via GPR41/FFA3. However, the antitumor action of GPR41/FFA3 has not been elucidated.

Methods

In this study, we examined AR420626 as a GPR41-selective agonist in HepG2 and HLE cells. Nude mice were used for HepG2 xenograft studies. The apoptotic effect of AR420626 was evaluated using flow cytometry analysis. Expression of apoptosis-related proteins and HDACs was evaluated by Western immunoblot. Gene silencing of HDAC 3/5/7 and GPR41 was performed using small interfering RNA. Expression of TNF-α mRNA was evaluated by TaqMan real-time polymerase chain reaction.

Results

We found that AR420626, a selective GPR41/FFA3 agonist, suppressed growth of HepG2 xenografts and inhibited proliferation of HCC cells by inducing apoptosis. AR420626 induced proteasome activation through mTOR phosphorylation, which reduced HDAC proteins, and then increased expression of TNF-α.

Conclusion

AR420626, a selective GPR41/FFA3 agonist, may be a candidate as a therapeutic agent for HCC.

Short-chain fatty acid mitigates adenine-induced chronic kidney disease via FFA2 and FFA3 pathways

Short-chain fatty acids (SCFAs), including acetate, butyrate, and propionate, are produced when colonic bacteria in the human gastrointestinal tract ferment undigested fibers. Free fatty acid receptor 2 (FFA2) and FFA3 are G-protein-coupled receptors recently identified as SCFA receptors that may modulate inflammation. We previously showed through in vitro experiments that SCFAs activate FFA2 and FFA3, thereby mitigating inflammation in human renal cortical epithelial cells. This study used a murine model of adenine-induced renal failure to investigate whether or not SCFAs can prevent the progression of renal damage. We also examined whether or not these FFA2 and FFA3 proteins have some roles in this protective mechanism in vivo. Immunohistochemical analyses of mouse kidneys showed that FFA2 and FFA3 proteins were expressed mainly in the distal renal tubules and collecting tubules. First, we observed that the administration of propionate mitigated the renal dysfunction and pathological deterioration caused by adenine. Consistent with this, the expression of inflammatory cytokines and fibrosis-related genes was reduced. Furthermore, the mitigation of adenine-induced renal damage by the administration of propionate was significantly attenuated in FFA2^-/- and FFA3^-/- mice. Therefore, the administration of propionate significantly protects against adenine-induced renal failure, at least in part, via the FFA2 and FFA3 pathways. Our data suggest that FFA2 and FFA3 are potential new therapeutic targets for preventing or delaying the progression of chronic kidney disease.

β-Hydroxybutyrate enhances the cytotoxic effect of cisplatin via the inhibition of HDAC/survivin axis in human hepatocellular carcinoma cells

Ketone bodies, including acetoacetate and β-hydroxybutyrate (βOHB), are produced from acetyl coenzyme A in the liver and then secreted into the blood. These molecules are a source of energy for peripheral tissues during exercise or fasting. βOHB has been reported to inhibit histone deacetylases (HDACs) 1, 3, and 4 in human embryonic kidney 293 cells. Thus, βOHB may regulate epigenetics by modulating HDACs. There have been several reports that the administration of βOHB or induction of a physiological state of ketosis has an antitumor effect; however, the mechanism remains unclear. The aim of this study was to investigate whether βOHB enhances cisplatin-induced apoptosis in hepatocellular carcinoma (HCC) cells by modulating activity and/or expression of HDACs. We found that βOHB significantly enhanced cisplatin-induced apoptosis and cleavage of caspase-3 and -8 in HCC cells. Further, βOHB significantly decreased the expression of HDCA 3/5/6 and survivin in liver hepatocellular (HepG2) cells. In HDAC3/6 gene silencing, survivin expression was significantly decreased, and cisplatin-induced cleavage of caspase-3 was significantly enhanced compared with control in HepG2 cells. In conclusion, βOHB enhanced cisplatin-induced apoptosis via HDAC3/6 inhibition/survivin axis in HepG2 cells, which suggests that βOHB could be a new adjuvant agent for cisplatin chemotherapy.

Connectivity mapping of angiotensin-PPAR interactions involved in the amelioration of non-alcoholic steatohepatitis by Telmisartan

Nonalcoholic fatty liver disease (NAFLD) is a global health problem that is associated with various metabolic disorders. Telmisartan is a potential treatment for NAFLD due to its ability to improve insulin sensitivity and decrease hepatic fat accumulation via modulation of PPARγ, and to suppress hepatic fibrosis by blocking angiotensin II receptors. However, the underlying mechanisms of action of telmisartan have yet to be fully elucidated. In the present study, diabetic nonalcoholic steatohepatitis (NASH) mice (STAM mice) received daily administrations of telmisartan for 6 weeks to assess the improvements in NASH. Hepatic transcriptome analyses revealed that the amelioration of NASH likely occurred through the regulation of inflammatory- and fibrosis-related gene responses. An integrated network analysis including transcriptional and non-transcriptional genes regulated by telmisartan showed that the NAFLD pathway is interconnected with the dysregulated RAS-PPAR-NFκB pathways. The downstream targets of PPARα, PPARδ, and RELA in this network significantly overlapped with telmisartan-induced differentially expressed genes (DEGs), which were verified in palmitate-treated Hepa1c1c7 cell line. This transcriptome approach accompanied with cell-based molecular analyses provided the opportunity to understand the fundamental molecular mechanisms underpinning the therapeutic effects of telmisartan, and will contribute to the establishment of a novel pharmacological treatment for NASH patients.

[Effect of telmisartan on expression of metadherin in the kidney of mice with unilateral ureter obstruction]

OBJECTIVE

To explore the effect of telmisartan on the expression of metadherin in the kidney of mice with unilateral ureter obstruction.

METHODS

Eighteen male C57 mice were randomized into sham-operated group, model group and telmisartan treatment group. In the latter two groups, renal interstitial fibrosis as the result of unilateral ureter obstruction (UUO) was induced by unilateral ureteral ligation with or without telmisartan intervention. Renal pathological changes of the mice were assessed using Masson staining, and immunohistochemistry and Western blotting were used to detect the expression of extracellular matrix proteins and metadherin in the kidney of the mice. In the in vitro experiment, cultured mouse renal tubular epithelial cells (mTECs) were stimulated with transforming growth factor-β1 (TGF-β1) and transfected with a siRNA targeting metadherin, and the changes in the expressions of extracellular matrix proteins and metadherin were detected using Western blotting.

RESULTS

The expressions of extracellular matrix proteins and metadherin increased significantly in the kidney of mice with UUO (P < 0.05). Intervention with telmisartan significantly lowered the expressions of extracellular matrix proteins and metadherin and alleviated the pathology of renal fibrosis in mice with UUO (P < 0.05). In cultured mTECs, siRNA-mediated knockdown of metadherin obviously reversed TGF-β1-induced increase in the expressions of extracellular matrix proteins and metadherin.

CONCLUSIONS

Telmisartan can suppress the production of extracellular matrix proteins and the expression of metadhein to attenuate UUO-induced renal fibrosis in mice.

Diabetic nephropathy: An update on pathogenesis and drug development

Diabetic nephropathy (DN) is a major cause of end-stage renal disease and affects a large number of individuals with diabetes. However, the development of specific treatments for DN has not yet been identified. Hence, this review is concisely designed to understand the molecular pathways leading to DN in order to develop suitable therapeutic strategies. Extensive literature search have been carried in regard with the pathogenesis and pathophysiology of DN, drug targets and updates on clinical trials, the consequences associated with DN and the potential biomarkers for diagnosis and prediction of DN are discussed in this review. DN is characterised by microalbuminuria and macroalbuminuria, and morphological changes such as glomerular thickening, interstitial fibrosis, formation of nodular glomerulosclerosis and decreased endothelial cell fenestration. Besides, the involvement of renin-angiotensin-aldosterone system, inflammation and genetic factors are the key pathways in the progression of DN. In regard with drug development drugs targeted to epidermal growth factor, inflammatory cytokines, ACTH receptor and TGFβ1 receptors are in pipeline for clinical trials whereas, several drugs have also failed in phase III and phase IV of clinical trials due to lack of efficacy and severe adverse effect. The research on DN is limited with respect to its pathogenesis and drug development. Thus, a more detailed understanding of the pathogenesis of DN is very essential to progress in the drug development process.

A short-chain fatty acid, propionate, enhances the cytotoxic effect of cisplatin by modulating GPR41 signaling pathways in HepG2 cells

Short-chain fatty acids (SCFAs) such as acetate, propionate, and butyrate are generated by microbial fermentation of indigestible fiber by gut flora. SCFAs are ligands of two orphan G protein-coupled receptors, GPR41 and GPR43, that modulate cell proliferation and induce apoptosis. However, it is unclear if SCFAs enhance the effects of chemotherapy in a GPR41- or GPR43-dependent manner. The aim of this study was to investigate whether SCFAs, and particularly propionate, activate GPR41 or GPR43, and thereby enhance the antitumor effects of cisplatin in HepG2 human hepatocellular carcinoma (HCC) cells. The inhibitory effects of propionate and cisplatin on proliferation of HCC cells were determined by MTS assay. Changes in apoptosis rate were analyzed by flow cytometry. The effects of combined propionate and cisplatin on these properties in HCC cells were significantly higher than those of cisplatin alone. With combined treatment, the levels of cleaved caspase-3, active caspase-3 forms, and acetylated histone H3 were enhanced in a GPR41-dependent manner; expression of histone deacetylases (HDAC) 3, 4, 5, 6, 8 proteins was significantly reduced; and induction of TNF-α expression was significantly enhanced. These results suggest that propionate and cisplatin synergistically and significantly induce apoptosis of HepG2 cells by increasing expression of autocrine TNF-α via reduction of HDACs through GPR41 signaling. From clinical and translational perspectives, our data suggest that a combination of propionate with cisplatin may have better therapeutic effects on HCC compared with conventional treatment, and that a selective GPR41 agonist may be a candidate as an adjuvant therapeutic agent for HCC.

Drug-Mediated Shortening of Action Potentials in LQTS2 Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes

Cardiomyocytes (CMs) derived from human induced pluripotent stem cells (hiPSCs) are now a well-established modality for modeling genetic disorders of the heart. This is especially so for long QT syndrome (LQTS), which is caused by perturbation of ion channel function, and can lead to fainting, malignant arrhythmias and sudden cardiac death. LQTS2 is caused by mutations in KCNH2, a gene whose protein product contributes to I_Kr (also known as HERG), which is the predominant repolarizing potassium current in CMs. β-blockers are the mainstay treatment for patients with LQTS, functioning by reducing heart rate and arrhythmogenesis. However, they are not effective in around a quarter of LQTS2 patients, in part, because they do not correct the defining feature of the condition, which is excessively prolonged QT interval. Since new therapeutics are needed, in this report, we biopsied skin fibroblasts from a patient who was both genetically and clinically diagnosed with LQTS2. By producing LQTS-hiPSC-CMs, we assessed the impact of different drugs on action potential duration (APD), which is used as an in vitro surrogate for QT interval. Not surprisingly, the patient's own β-blocker medication, propranolol, had a marginal effect on APD in the LQTS-hiPSC-CMs. However, APD could be significantly reduced by up to 19% with compounds that enhanced the I_Kr current by direct channel binding or by indirect mediation through the PPARδ/protein 14-3-3 epsilon/HERG pathway. Drug-induced enhancement of an alternative potassium current, I_KATP, also reduced APD by up to 21%. This study demonstrates the utility of LQTS-hiPSC-CMs in evaluating whether drugs can shorten APD and, importantly, shows that PPARδ agonists may form a new class of therapeutics for this condition.

Short-chain fatty acids, GPR41 and GPR43 ligands, inhibit TNF-α-induced MCP-1 expression by modulating p38 and JNK signaling pathways in human renal cortical epithelial cells

Short-chain fatty acids (SCFAs), such as acetate, propionate, and butyrate, are produced predominantly by gut microbiota fermentation of dietary fiber. SCFAs are newly identified as endogenous ligands of two orphan G protein-coupled receptors, GPR41 and GPR43, which have the potential to modulate inflammation. Therefore, GPR41 and GPR43 may mediate the link between the gut microbiome status and various disease conditions including renal inflammation. This study aimed at investigating whether SCFAs activate GPR41 and GPR43, and thereby exert anti-inflammatory effects in human renal cortical epithelial cells (HRCEs) as a main component of kidney tissue. Immunohistochemical analyses of human renal biopsy specimens revealed the expression of GPR41 and GPR43 protein in the distal renal tubules and collecting tubules. TNF-α increased the expression of monocyte chemoattractant protein-1 (MCP-1), a potential fibrotic inducer, at least partly via enhancing phosphorylation of p38 and JNK in HRCEs. SCFAs, especially propionate, attenuated TNF-α- stimulated MCP-1 expression by inhibiting the phosphorylation of p38 and JNK. This inhibitory effect was considerably attenuated by an inactivator of the Gi/o-type G protein and a Gβγ (i/o) blocker, but not by a Gα (i/o) blocker. Furthermore, SCFA-mediated inhibition of MCP-1 expression was significantly blocked by siRNA-induced gene silencing of GPR41 and GPR43. In conclusion, SCFAs lowered TNF-α-induced MCP-1 expression by reducing phosphorylation of p38 and JNK in a GPR41/43-dependent manner in HRCEs, suggesting that SCFA modification may be a new therapeutic tool for preventing progression of renal inflammation and fibrosis.

Telmisartan improves cardiac fibrosis in diabetes through peroxisome proliferator activated receptor δ (PPARδ): from bedside to bench

BACKGROUND

Despite the known risk of diabetes-induced cardiac fibrosis, less is known about whether diabetes causes an altered cardiac phenotype independent of coronary atherosclerosis. Peroxisome proliferator-activated receptor δ (PPARδ), a versatile regulator of metabolic homeostasis, may be a potential therapeutic target. Herein we investigated the effectiveness of telmisartan, a unique angiotensin receptor blocker that increases PPARδ expression, in improving left ventricular remodeling in diabetic humans and rats.

METHODS

In this longitudinal, prospective study, we enrolled 15 diabetic patients receiving telmisartan (20 mg/day) for 12 weeks. After treatment, strain was measured and compared with the baseline value. Using streptozotocin to induce type 1 diabetes rat model, we measured PPARδ expression and downstream targets.

RESULTS

After treatment with telmisartan, both longitudinal and circumferential strains improved in diabetic patients. Compared with that of controls, the diabetic rat heart developed significant fibrosis, which markedly decreased after treatment with telmisartan (30 mg/kg/day, orally) for 7 days. After incubation with 30 mM glucose, rat cardiomyocytes showed a significant down-regulation of PPARδ. Interestingly, the increased expression of fibrosis-associated proteins, including signal transducer and activator of transcription 3 (STAT3) was attenuated by the co-incubation of GW0742, a PPARδ agonist. By knockdown or inhibition of STAT3, the hyperglycemia related high expression of fibrosis associated targets was reversed. Independent from the hyperglycemic incubation, STAT3 over-expression led to similar results. Conversely, in the presence of GSK0660, a PPARδ inhibitor, the protective effects of telmisartan were diminished.

CONCLUSION

Telmisartan improved the hyperglycemia-induced cardiac fibrosis through the PPARδ/STAT3 pathway. Graphical abstract Summary of the mechanism of telmisartan's effect on the suppression of hyperglycemia-induced cardiac fibrosis through PPARδ instead of the AMPK pathway. PPARδ peroxisome proliferator-activated receptor δ, STAT3 signal transducer and activator of transcription 3, CTGF connective tissue growth factor, MMP9 matrix metallopeptidase 9.

Effects of telmisartan on fat distribution: a meta-analysis of randomized controlled trials

OBJECTIVES

Several meta-analyses have confirmed the positive metabolic effects of telmisartan, an angiotensin II receptor blocker that can also act as a partial peroxisome proliferator-activated receptor-γ agonist, compared to those of other angiotensin II receptor blockers. These effects include decreased fasting glucose, glycosylated hemoglobin, interleukin-6, and tumor necrosis factor-α levels. However, no systemic analysis of telmisartan's effects on body fat distribution has been performed. We performed a meta-analysis of randomized controlled telmisartan trials to investigate its effects on body weight, fat distribution, and visceral adipose reduction.

RESEARCH DESIGN AND METHODS

A literature search was performed using Embase, MEDLINE, and the Cochrane Library between January 1966 and November 2013. Randomized controlled trials in English and meeting the following criterion were included: random assignment of hypertensive participants with overweight/obesity, metabolic syndrome, or glucose intolerance to telmisartan or control therapy group.

RESULTS

Of 651 potentially relevant reports, 15 satisfied the inclusion criterion. While visceral fat area was significantly lower in the telmisartan group than in the control group (weighted mean difference = -18.13 cm(2), 95% C.I. = -27.16 to -9.11, Pχ(2) = 0.19, I(2) = 41%), subcutaneous fat area was similar (weighted mean difference =2.94 cm(2), 95% C.I. = -13.01 to 18.89, Pχ(2) = 0.30, I(2) = 17%). Total cholesterol levels were significantly different between the groups (standardized mean difference = -0.24, 95% C.I. = -0.45 to -0.03, Pχ(2) = 0.0002, I(2) = 67%).

LIMITATIONS

Limitations include: (1) limited number of studies, especially those evaluating fat distribution; (2) different imaging modalities to assess visceral fat area (V.F.A.) and subcutaneous fat area (S.F.A.); (3) observed heterogeneity.

CONCLUSION

The findings suggest that telmisartan affected fat distribution, inducing visceral fat reduction, and thus could be useful in hypertensive patients with obesity/overweight, metabolic syndrome, or glucose intolerance.

Histone deacetyltransferase inhibitors Trichostatin A and Mocetinostat differentially regulate MMP9, IL-18 and RECK expression, and attenuate Angiotensin II-induced cardiac fibroblast migration and proliferation

Histone acetylation/deacetylation plays a key role in the epigenetic regulation of multiple pro-fibrotic genes. Here we investigated the effects of histone deacetyltransferase (HDAC) inhibition on angiotensin (Ang)-II-induced pro-fibrotic changes in adult mouse cardiac fibroblasts (CF). CF express class I HDACs 1 and 2, and Ang-II induces their activation. Notably, silencing HDAC1 or HDAC2 attenuated Ang-II induced CF proliferation and migration. Under basal conditions, HDAC1 dimerizes with HDAC2 in CF and Ang-II reversed this interaction. Treatment with Trichostatin A (TSA), a broad-spectrum HDAC inhibitor, restored their physical association, and attenuated Ang-II-induced MMP9 expression, IL-18 induction, and extracellular matrix (collagen I, collagen III and fibronectin) production. Further, TSA inhibited Ang-II-induced MMP9 and Il18 transcription by blocking NF-κB and AP-1 binding to their respective promoter regions. By inhibiting Sp1 binding to RECK promoter, TSA reversed Ang-II-induced RECK suppression, collagen and fibronectin expression, and CF migration and proliferation. The class I-specific HDAC inhibitor Mocetinostat (MGCD) recapitulated TSA effects on Ang-II-treated CF. Together, these results demonstrate that targeting HDACs attenuates the pro-inflammatory and pro-fibrotic effects of Ang-II on CF.

Angiotensin II type 1 receptor antagonists in animal models of vascular, cardiac, metabolic and renal disease

We have reviewed the effects of angiotensin II type 1 receptor antagonists (ARBs) in various animal models of hypertension, atherosclerosis, cardiac function, hypertrophy and fibrosis, glucose and lipid metabolism, and renal function and morphology. Those of azilsartan and telmisartan have been included comprehensively whereas those of other ARBs have been included systematically but without intention of completeness. ARBs as a class lower blood pressure in established hypertension and prevent hypertension development in all applicable animal models except those with a markedly suppressed renin-angiotensin system; blood pressure lowering even persists for a considerable time after discontinuation of treatment. This translates into a reduced mortality, particularly in models exhibiting marked hypertension. The retrieved data on vascular, cardiac and renal function and morphology as well as on glucose and lipid metabolism are discussed to address three main questions: 1. Can ARB effects on blood vessels, heart, kidney and metabolic function be explained by blood pressure lowering alone or are they additionally directly related to blockade of the renin-angiotensin system? 2. Are they shared by other inhibitors of the renin-angiotensin system, e.g. angiotensin converting enzyme inhibitors? 3. Are some effects specific for one or more compounds within the ARB class? Taken together these data profile ARBs as a drug class with unique properties that have beneficial effects far beyond those on blood pressure reduction and, in some cases distinct from those of angiotensin converting enzyme inhibitors. The clinical relevance of angiotensin receptor-independent effects of some ARBs remains to be determined.

Inhibition of endoplasmic reticulum stress-activated IRE1α-TRAF2-caspase-12 apoptotic pathway is involved in the neuroprotective effects of telmisartan in the rotenone rat model of Parkinson's disease

Telmisartan, one unique angiotensin II type 1 receptor blocker, has been attracting attention due to its putative peroxisome proliferator-activated receptor (PPAR)-γ or β/δ actions. Recently, telmisartan has been reported to exert neuroprotective effects in animal models of Parkinson's disease (PD). However, the underlying mechanisms have not been fully clarified. Recently, accumulating evidence has shown that endoplasmic reticulum (ER) stress plays a crucial role in rotenone-induced neuronal apoptosis. Additionally, studies have revealed that inositol-requiring enzyme/endonuclease 1α (IRE1α) is necessary and sufficient to trigger ER stress. In the present study, we aimed to determine whether ER stress-activated IRE1α-mediated apoptotic pathway is involved in the neuroprotection of telmisartan in the rotenone rats of PD and explore the possible involvement of PPAR-β/δ activation. The catalepsy tests were performed to test the catalepsy symptom. The dopamine content and α-synuclein expression were ascertained through high-performance liquid chromatography and immunohistochemistry, respectively. The expression of IRE1α, TNF receptor associated factor 2 (TRAF2), caspase-12 and PPAR-β/δ was detected by western blot. Neuronal apoptosis was assessed by TUNEL and immunohistochemistry. Our results show that telmisartan ameliorated the catalepsy symptom and attenuated dopamine depletion as well as α-synuclein accumulation. Moreover, telmisartan decreased ER stress-mediated neuronal apoptosis. Furthermore, telmisartan inhibited IRE1α-TRAF2-caspase-12 apoptotic signaling pathway. Additionally, telmisartan activated PPAR β/δ, implying that PPAR-β/δ activation properties of telmisartan are possibly or partially involved in the neuroprotective effects. In conclusion, our findings suggest that suppressing ER stress-activated IRE1α-TRAF2-caspase-12 apoptotic pathway is involved in the neuroprotective effects of telmisartan in the rotenone rats of PD.

Telmisartan, a possible PPAR-δ agonist, reduces TNF-α-stimulated VEGF-C production by inhibiting the p38MAPK/HSP27 pathway in human proximal renal tubular cells

Vascular endothelial growth factor-C (VEGF-C) is a main inducer of inflammation-associated lymphangiogenesis in various inflammatory disorders including chronic progressive kidney diseases, for which angiotensin II receptor type 1 blockers (ARBs) are widely used as the main treatment. Although proximal renal tubular cells may affect the formation of lymphatic vessels in the interstitial area by producing VEGF-C, the molecular mechanisms of VEGF-C production and its manipulation by ARB have not yet been examined in human proximal renal tubular epithelial cells (HPTECs). In the present study, TNF-α dose-dependently induced the production of VEGF-C in HPTECs. The TNF-α-induced production of VEGF-C was mediated by the phosphorylation of p38MAPK and HSP27, but not by that of ERK or NFkB. Telmisartan, an ARB that can activate the peroxisome proliferator-activated receptor (PPAR), served as a PPAR-δ activator and reduced the TNF-α-stimulated production of VEGF-C. This reduction was partially attributed to a PPAR-δ-dependent decrease in p38MAPK phosphorylation. Our results indicate that TNF-α induced the production of VEGF-C in HPTECs by activating p38MAPK/HSP27, and this was partially inhibited by telmisartan in a PPAR-δ dependent manner. These results provide a novel insight into inflammation-associated lymphangiogenesis.