Telmisartan but not valsartan inhibits TGF-β-mediated accumulation of extracellular matrix via activation of PPARγ

The role of neuroinflammation in canine epilepsy

The lack of therapeutics that prevent the development of epilepsy, improve disease prognosis or overcome drug resistance represents an unmet clinical need in veterinary as well as in human medicine. Over the past decade, experimental studies and studies in human epilepsy patients have demonstrated that neuroinflammatory processes are involved in epilepsy development and play a key role in neuronal hyperexcitability that underlies seizure generation. Targeting neuroinflammatory signaling pathways may provide a basis for clinically relevant disease-modification strategies in general, and moreover, could open up new therapeutic avenues for human and veterinary patients with drug-resistant epilepsy. A sound understanding of the neuroinflammatory mechanisms underlying seizure pathogenesis in canine patients is therefore essential for mechanism-based discovery of selective epilepsy therapies that may enable the development of new disease-modifying treatments. In particular, subgroups of canine patients in urgent needs, e.g. dogs with drug-resistant epilepsy, might benefit from more intensive research in this area. Moreover, canine epilepsy shares remarkable similarities in etiology, disease manifestation, and disease progression with human epilepsy. Thus, canine epilepsy is discussed as a translational model for the human disease and epileptic dogs could provide a complementary species for the evaluation of antiepileptic and antiseizure drugs. This review reports key preclinical and clinical findings from experimental research and human medicine supporting the role of neuroinflammation in the pathogenesis of epilepsy. Moreover, the article provides an overview of the current state of knowledge regarding neuroinflammatory processes in canine epilepsy emphasizing the urgent need for further research in this specific field. It also highlights possible functional impact, translational potential and future perspectives of targeting specific inflammatory pathways as disease-modifying and multi-target treatment options for canine epilepsy.

Breaking the niche: multidimensional nanotherapeutics for tumor microenvironment modulation

Most of the current antitumor therapeutics were developed targeting the cancer cells only. Unfortunately, in the majority of tumors, this single-dimensional therapy is found to be ineffective. Advanced research has shown that cancer is a multicellular disorder. The tumor microenvironment (TME), which is made by a complex network of the bulk tumor cells and other supporting cells, plays a crucial role in tumor progression. Understanding the importance of the TME in tumor growth, different treatment modalities have been developed targeting these supporting cells. Recent clinical results suggest that simultaneously targeting multiple components of the tumor ecosystem with drug combinations can be highly effective. This type of "multidimensional" therapy has a high potential for cancer treatment. However, tumor-specific delivery of such multi-drug combinations remains a challenge. Nanomedicine could be utilized for the tumor-targeted delivery of such multidimensional therapeutics. In this review, we first give a brief overview of the major components of TME. We then highlight the latest developments in nanoparticle-based combination therapies, where one drug targets cancer cells and other drug targets tumor-supporting components in the TME for a synergistic effect. We include the latest preclinical and clinical studies and discuss innovative nanoparticle-mediated targeting strategies.

Telmisartan as an add-on treatment for dogs with refractory idiopathic epilepsy: a nonrandomized, uncontrolled, open-label clinical trial

OBJECTIVE

To evaluate the effect on seizure frequency of add-on telmisartan treatment in dogs with refractory idiopathic epilepsy.

ANIMALS

11 client-owned dogs with idiopathic epilepsy and ≥ 2 generalized seizures/mon that were currently being treated with ≥ 2 antiepileptic drugs.

PROCEDURES

Telmisartan was administered at a dosage of 0.25 to 1 mg/kg, PO, every 12 hours for 4 to 16 months. Seizure frequencies before and during telmisartan treatment were recorded.

RESULTS

10 dogs completed the 4-month treatment protocol. One dog was excluded owing to a transient increase in serum creatinine concentration; no adverse effects of telmisartan were observed in the remaining 10 dogs. A reduction in seizure frequency greater than an estimated expected placebo effect of 30% was evident in 7 of the 10 dogs. Long-term (12 to 16 months) follow-up information was available for 6 dogs, of which 4 had a further reduction in seizure frequency. Differences in seizure frequency were not statistically significant. No significant difference was found in serum phenobarbital concentration throughout the treatment period in the 7 dogs that were tested.

CLINICAL RELEVANCE

Telmisartan has the potential to reduce seizure frequency when administered as an add-on antiepileptic drug in dogs with refractory idiopathic epilepsy. A randomized, double-blind, placebo-controlled trial is needed to determine the true efficacy of telmisartan. On the basis of our results, a sample size of 54 dogs with refractory idiopathic epilepsy would be needed.

Oral vitamin-A-coupled valsartan nanomedicine: High hepatic stellate cell receptors accessibility and prolonged enterohepatic residence

So far, liver fibrosis still has no clinically-approved treatment. The loss of stored vitamin-A (V_A) in hepatic stellate cells (HSCs), the main regulators to hepatic fibrosis, can be applied as a mechanism for their targeting. Valsartan is a good candidate for this approach; it is a marketed oral-therapy with inverse- and partial-agonistic activity to the over-expressed angiotensin-II type1 receptor (AT1R) and depleted nuclear peroxisome proliferator-activated receptor-gamma (PPAR-γ), respectively, in activated HSCs. However, efficacy on AT1R and PPAR-γ necessitates high drug permeability which is lacking in valsartan. In the current study, liposomes were used as nanocarriers for valsartan to improve its permeability and hence efficacy. They were coupled to V_A and characterized for HSCs-targeting. Tracing of orally-administered fluorescently-labeled V_A-coupled liposomes in normal rats and their fluorescence intensity quantification in different organs convincingly demonstrated their intestinal entrapment. On the other hands, their administration to rats with induced fibrosis revealed preferential hepatic, and less intestinal, accumulation which lasted up to six days. This indicated their uptake by intestinal stellate cells that acted as a depot for their release over time. Confocal microscopical examination of immunofluorescently-stained HSCs in liver sections, with considerable formula accumulation, confirmed HSCs-targeting and nuclear uptake. Consequently, V_A-coupled valsartan-loaded liposomes (VLC)-therapy resulted in profound re-expression of hepatic Mas-receptor and PPAR-γ, potent reduction of fibrogenic mediators' level and nearly normal liver function tests. Therefore, VLC epitomizes a promising antifibrotic therapy with exceptional extended action and additional PPAR-γ agonistic activity.

Renoprotective effect of a combination of garlic and telmisartan against ischemia/reperfusion-induced kidney injury in obese rats

Obesity enhances the frequency and severity of acute kidney injury (AKI). Telmisartan pre-treatment was used experimentally in the amelioration of ischemia/reperfusion (IR)-induced AKI. However, there is a lack of evidence regarding its beneficial effects on AKI in obese animals. The present study, therefore, aimed to explore the protective effects of garlic and/or telmisartan against renal damage induced by unilateral IR in obese rats. Meloxicam was used as a standard anti-inflammatory agent. Prophylactic oral administration of meloxicam (3 mg kg(-1)), garlic (500 mg kg(-1)) and/or telmisartan (5 and 10 mg kg(-1)) for 4 wk protected against renal function deterioration induced by IR in obese rats. Both doses of telmisartan significantly reduced serum total cholesterol and triacyglycerol levels as well as peri-renal adipocytes size and renal fibrosis. Renal nuclear factor-kappa B immunoreactivity, tumor necrosis factor-alpha content as well as interleukin-10, adiponectin receptor 1 and macrophages (M1, M2) polarization markers (CD11c, CD206) mRNA expressions were down-regulated in ischemic kidney tissues and white adipose tissues around them by all treatments. Moreover, garlic, telmisartan and their combinations significantly suppressed oxidative stress in renal ischemic tissues. Histological picture was also improved by these treatments. Interestingly, the combinations provided a greater protection than their monotherapy in a dose-dependent manner. We suppose that this combination may be a promising prophylactic regimen for managing AKI in case of obesity. Thus, future experimental and clinical large-scale studies are necessary.

Pentoxifylline inhibits liver fibrosis via hedgehog signaling pathway

Infection of schistosomiasis japonica may eventually lead to liver fibrosis, and no effective antifibrotic therapies are available but liver transplantation. Hedgehog (HH) signaling pathway has been involved in the process and is a promising target for treating liver fibrosis. This study aimed to explore the effects of pentoxifylline (PTX) on liver fibrosis induced by schistosoma japonicum infection by inhibiting the HH signaling pathway. Phorbol12-myristate13-acetate (PMA) was used to induce human acute mononuclear leukemia cells THP-1 to differentiate into macrophages. The THP-1-derived macrophages were stimulated by soluble egg antigen (SEA), and the culture supernatants were collected for detection of activation of macrophages. Cell Counting Kit-8 (CCK-8) was used to detect the cytotoxicity of the culture supernatant and PTX on the LX-2 cells. The LX-2 cells were administered with activated culture supernatant from macrophages and(or) PTX to detect the transforming growth factor-β gene expression. The mRNA expression of shh and gli-1, key parts in HH signaling pathway, was detected. The mRNA expression of shh and gli-1 was increased in LX-2 cells treated with activated macrophages-derived culture supernatant, suggesting HH signaling pathway may play a key role in the activation process of hepatic stellate cells (HSCs). The expression of these genes decreased in LX-2 cells co-cultured with both activated macrophages-derived culture supernatant and PTX, indicating PTX could suppress the activation process of HSCs. In conclusion, these data provide evidence that PTX prevents liver fibrogenesis in vitro by the suppression of HH signaling pathway.

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.

A systematic comparison of the properties of clinically used angiotensin II type 1 receptor antagonists

Angiotensin II type 1 receptor antagonists (ARBs) have become an important drug class in the treatment of hypertension and heart failure and the protection from diabetic nephropathy. Eight ARBs are clinically available [azilsartan, candesartan, eprosartan, irbesartan, losartan, olmesartan, telmisartan, valsartan]. Azilsartan (in some countries), candesartan, and olmesartan are orally administered as prodrugs, whereas the blocking action of some is mediated through active metabolites. On the basis of their chemical structures, ARBs use different binding pockets in the receptor, which are associated with differences in dissociation times and, in most cases, apparently insurmountable antagonism. The physicochemical differences between ARBs also manifest in different tissue penetration, including passage through the blood-brain barrier. Differences in binding mode and tissue penetration are also associated with differences in pharmacokinetic profile, particularly duration of action. Although generally highly specific for angiotensin II type 1 receptors, some ARBs, particularly telmisartan, are partial agonists at peroxisome proliferator-activated receptor-γ. All of these properties are comprehensively reviewed in this article. Although there is general consensus that a continuous receptor blockade over a 24-hour period is desirable, the clinical relevance of other pharmacological differences between individual ARBs remains to be assessed.

Telmisartan improves kidney function through inhibition of the oxidative phosphorylation pathway in diabetic rats

Telmisartan provides renal benefit at all stages of the renal continuum in patients with type 2 diabetes mellitus. This research is to investigate the effect of telmisartan on kidney function in diabetic rats and to identify the underlying molecular mechanisms. Diabetic rats were divided into vehicle group, low dosage (TeL) group, and high dosage of telmisartan (TeH) group. We performed Illumina RatRef-12 Expression BeadChip gene array experiments. We found 3-months of treatment with telmisartan significantly decreased 24-h urinary albumin, serum creatinine, blood urea nitrogen, and increased creatinine clearance rate. Kidney hypertrophy and glomerular mesangial matrix expansion were ameliorated. The glomeruli from the TeH group had 1541 genes with significantly changed expression (554 increased, 987 decreased). DAVID (Database for annotation, visualization and Integrated discovery) analyses showed that the most enriched term was 'mitochondrion' (Gene Ontology (GO:0005739)) in all 67 GO functional categories. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses indicated that all differentially expressed genes included seven KEGG pathways. Of those pathways, four are closely related to the oxidative phosphorylation pathway. Quantitative real-time PCR verified that the H+ transporting mitochondrial F1 complex, beta subunit (Atp5b), cytochrome c oxidase subunit VIc (Cox6c), and NADH dehydrogenase (ubiquinone) Fe-S protein 3 (Ndufs3) were significantly downregulated both in TeL and TeH groups, while nephrosis 1 homolog (Nphs1) and nephrosis 2 homolog (Nphs2) were significantly upregulated. The increased expression of malonaldehyde and NDUFS3 in the glomeruli of diabetic rats was attenuated by telmisartan. The other significantly changed pathway we found was the peroxisome proliferator-activated receptor (PPAR) signaling pathway. Our data suggest that telmisartan can improve kidney function in diabetic rats. The mechanism may be involved in mitochondrion oxidative phosphorylation, the PPAR-γ pathway, and the slit diaphragm.

Does interference with the renin-angiotensin system protect against diabetes? Evidence and mechanisms

Agents interfering with the renin-angiotensin system (RAS) were consistently shown to lower the incidence of type 2 diabetes mellitus (T2DM), as compared to other antihypertensive drugs, in hypertensive high-risk populations. The mechanisms underlying this protective effect of RAS blockade using angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers on glucose metabolism are not fully understood. In this article, we will review the evidence from randomized controlled trials and discuss the proposed mechanisms as to how RAS interference may delay the onset of T2DM. In particular, as T2DM is characterized by β-cell dysfunction and obesity-related insulin resistance, we address the mechanisms that underlie RAS blockade-induced improvement in β-cell function and insulin sensitivity.

Telmisartan provides better renal protection than valsartan in a rat model of metabolic syndrome

BACKGROUND

Angiotensin receptor blockers (ARB), telmisartan, and valsartan were compared for renal protection in spontaneously hypertensive rats (SHR) fed high fat diet. We hypothesized that in cardiometabolic syndrome, telmisartan an ARB with peroxisome proliferators activated receptor-γ (PPAR-γ) activity will offer better renal protection.

METHODS

SHR were fed either normal (SHR-NF, 7% fat) or high fat (SHR-HF, 36% fat) diet and treated with an ARB for 10 weeks.

RESULTS

Blood pressure was similar between SHR-NF (190 ± 3 mm Hg) and SHR-HF (192 ± 4 mm Hg) at the end of the 10 week period. Telmisartan and valsartan decreased blood pressure to similar extents in SHR-NF and SHR-HF groups. Body weight was significantly higher in SHR-HF (368 ± 5 g) compared to SHR-NF (328 ± 7 g). Telmisartan but not valsartan significantly reduced the body weight gain in SHR-HF. Telmisartan was also more effective than valsartan in improving glycemic and lipid status in SHR-HF. Monocyte chemoattractant protein-1 (MCP-1), an inflammatory marker, was higher in SHR-HF (24 ± 2 ng/d) compared to SHR-NF (14 ± 5 ng/d). Telmisartan reduced MCP-1 excretion in both SHR-HF and SHR-NF to a greater extent than valsartan. An indicator of renal injury, urinary albumin excretion increased to 85 ± 8 mg/d in SHR-HF compared to 54 ± 9 mg/d in SHR-NF. Telmisartan (23 ± 5 mg/d) was more effective than valsartan (45 ± 3 mg/d) in lowering urinary albumin excretion in SHR-HF. Moreover, telmisartan reduced glomerular damage to a greater extent than valsartan in the SHR-HF.

CONCLUSIONS

Collectively, our data demonstrate that telmisartan was more effective than valsartan in reducing body weight gain, renal inflammation, and renal injury in a rat model of cardiometabolic syndrome.

Differential susceptibility to epithelial-mesenchymal transition (EMT) of alveolar, bronchial and intestinal epithelial cells in vitro and the effect of angiotensin II receptor inhibition

The generation of myofibroblasts via epithelial-mesenchymal transition (EMT), a process through which epithelial cells lose their polarity and become motile mesenchymal cells, is a proposed contributory factor in fibrosis of a number of organs. Currently, it remains unclear to what extent epithelia of the upper airways and large intestine are susceptible to this process. Herein, we investigated the ability of model cell lines of alveolar (A549), bronchial (Calu-3) and colonic (Caco-2) epithelial cells to undergo EMT when challenged with transforming growth factor-β1 (TGF-β1) and other pro-inflammatory cytokines. Western blot and immunofluorescence microscopy demonstrated that A549 cells readily underwent EMT, as evidenced by a spindle-like morphology, increase in the mesenchymal marker, vimentin, and down-regulation of E-cadherin, an epithelial marker. In contrast, neither Calu-3 nor Caco-2 cells exhibited morphological changes nor alterations in marker expression associated with EMT. Moreover, whilst stimulation of A549 cells enhanced migration and reduced their proliferative capacity, no such effect was observed in epithelial cell lines of the bronchus or colon. In addition, concomitant treatment of A549 cells with telmisartan, an angiotensin II receptor antagonist with antifibrotic properties, was found to reduce cytokine-induced collagen I production and cell migration, although expression levels of vimentin and E-cadherin remained unaltered. Mechanistically, telmisartan failed to inhibit phosphorylation of Smad2/3. Together, these results, using representative in vitro models of the alveolus, bronchus and colon, tentatively suggest that epithelial cell plasticity and susceptibility to EMT may differ depending on its tissue origin. Furthermore, our investigations point to the beneficial effect of telmisartan in partial abrogation of alveolar EMT.