Cardioprotective effects of peroxisome proliferator activated receptor gamma activators on acute myocarditis: anti-inflammatory actions associated with nuclear factor kappaB blockade

The Role of the Immune System in Pathobiology and Therapy of Myocarditis: A Review

The role of the immune system in myocarditis onset and progression involves a range of complex cellular and molecular pathways. Both innate and adaptive immunity contribute to myocarditis pathogenesis, regardless of its infectious or non-infectious nature and across different histological and clinical subtypes. The heterogeneity of myocarditis etiologies and molecular effectors is one of the determinants of its clinical variability, manifesting as a spectrum of disease phenotype and progression. This spectrum ranges from a fulminant presentation with spontaneous recovery to a slowly progressing, refractory heart failure with ventricular dysfunction, to arrhythmic storm and sudden cardiac death. In this review, we first examine the updated definition and classification of myocarditis at clinical, biomolecular and histopathological levels. We then discuss recent insights on the role of specific immune cell populations in myocarditis pathogenesis, with particular emphasis on established or potential therapeutic applications. Besides the well-known immunosuppressive agents, whose efficacy has been already demonstrated in human clinical trials, we discuss the immunomodulatory effects of other drugs commonly used in clinical practice for myocarditis management. The immunological complexity of myocarditis, while presenting a challenge to simplistic understanding, also represents an opportunity for the development of different therapeutic approaches with promising results.

Citri Reticulatae Pericarpium protects against isoproterenol-induced chronic heart failure via activation of PPARγ

Background

Accumulated clinical trials and animal studies showed that Qiliqiangxin (QLQX), a traditional Chinese medicine formula containing extracts of 11 herbs, exerts beneficial effects on chronic heart failure (HF). Citri Reticulatae Pericarpium (CRP), one herbal medicine in QLQX, has been widely used in treatment against digestive, respiratory and cardiovascular diseases (CVDs) in China. However, the cardiac protective effects and mechanisms of CRP are still unclear.

Methods

The effects of CRP were investigated in isoproterenol (ISO)-induced chronic HF mice model and neonatal rat ventricular cardiomyocytes (NRVMs) treated with ISO. Echocardiography was used to determine cardiac function. Hematoxylin-eosin (HE) staining and α-actinin immunofluorescent staining were used to measure cardiomyocyte size. Cardiac fibrosis was evaluated by Masson’s trichrome staining. The expression of atrial natriuretic polypeptide (ANP) and brain natriuretic polypeptide (BNP) were determined by quantitative real time PCR (qRT-PCR). Western blot was applied to examine the expression of peroxisome proliferator-activated receptor gamma (PPARγ), PPARγ coactivator-1α (PGC-1α), fibrosis-related and apoptosis-related proteins.

Results

We found that CRP could significantly attenuate ISO-induced cardiac dysfunction, inhibit cardiac pathological hypertrophy and alleviate myocardial fibrosis and apoptosis. Mechanistically, the downregulation of PPARγ and PGC-1α in ISO-injected mice hearts and ISO-treated NRVMs could be reversed by CRP treatment. The beneficial effects of CRP against ISO-induced HF were abolished by PPARγ inhibitor (T0070907), suggesting that CRP-mediated PPARγ upregulation was essential for the preventive effect of CRP on ISO-induced cardiac dysfunction.

Conclusions

In conclusion, our study demonstrated that CRP attenuates ISO-induced cardiac remodeling via PPARγ activation, which represents a new application for CRP in the prevention of chronic HF.

Protective effects of pioglitazone against immunoglobulin deposition on heart of streptozotocin-induced diabetic rats

AIM

Peroxisome proliferator-activated receptor-γ (PPAR-γ) agonists have immunomodulatory and anti-inflammatory effects. The study investigated the autoimmune injuries of diabetic cardiomyopathy (DCM) and tested the hypothesis that PPAR-γ agonists suppress disordered immune responses in diabetic heart, thereby preventing evolution of DCM.

METHODS

STZ-induced diabetic rats were assigned to five groups: DM group, given no treatment; INS group, given insulin (4 U kg(-1) d(-1)); PIL group, given low dose pioglitazone (4 mg kg(-1) d(-1)); PIL/INS group, given both low dose pioglitazone and insulin; PIH group, given high dose pioglitazone (20 mg kg(-1) d(-1)). Normal rats (CON group) were also monitored as control. The pathologic abnormalities of hearts were observed. The immunoglobulin deposition was examined by immunohistochemistry and immunofluorescence.

RESULTS

At 16 weeks, interstitial fibrosis was shown in diabetic heart which was accompanied by plenty of inflammatory cells infiltrated. Pioglitazone therapy could ameliorate the cardiac injuries. Shown by immunohistochemistry, the difference of integrated optical density (IOD) of immunoglobulin deposition among each group had statistic significance. No obvious immunoglobulins were deposited in the intercellular substance of heart in CON group (IgA 290.8 ± 88.1, IgG 960.4 ± 316.0 and IgM 341.3 ± 67.9). But the deposition of immunoglobulins increased significantly in DM group (IgA 7,047.5 ± 1,328.3, P < 0.05; IgG 28,945.9 ± 5,160.7, P < 0.05 and IgM 8,580.8 ± 1,336.8, P < 0.05). Administration of pioglitazone greatly reduced the increased deposition in a dose-dependent fashion. Moreover, the statistical significance was the same with immunofluorescence analysis as with immunohistochemical examination.

CONCLUSIONS

The data suggest that disordered immune responses play an important role in the pathogenesis of DCM. Pioglitazone showed protective effects by inhibiting the immunoglobulin deposition on diabetic myocardium.

15-deoxy-Δ¹²,¹⁴-PGJ₂ promotes inflammation and apoptosis in cardiomyocytes via the DP2/MAPK/TNFα axis

Background

Prostaglandins (PGs), lipid autacoids derived from arachidonic acid, play a pivotal role during inflammation. PGD₂ synthase is abundantly expressed in heart tissue and PGD₂ has recently been found to induce cardiomyocyte apoptosis. PGD₂ is an unstable prostanoid metabolite; therefore the objective of the present study was to elucidate whether its final dehydration product, 15-deoxy-Δ^12,14-PGJ₂ (15d-PGJ₂, present at high levels in ischemic myocardium) might cause cardiomyocyte damage.

Methods and results

Using specific (ant)agonists we show that 15d-PGJ₂ induced formation of intracellular reactive oxygen species (ROS) and phosphorylation of p38 and p42/44 MAPKs via the PGD₂ receptor DP2 (but not DP1 or PPARγ) in the murine atrial cardiomyocyte HL-1 cell line. Activation of the DP2-ROS-MAPK axis by 15d-PGJ₂ enhanced transcription and translation of TNFα and induced apoptosis in HL-1 cardiomyocytes. Silencing of TNFα significantly attenuated the extrinsic (caspase-8) and intrinsic apoptotic pathways (bax and caspase-9), caspase-3 activation and downstream PARP cleavage and γH2AX activation. The apoptotic machinery was unaffected by intracellular calcium, transcription factor NF-κB and its downstream target p53. Of note, 9,10-dihydro-15d-PGJ₂ (lacking the electrophilic carbon atom in the cyclopentenone ring) did not activate cellular responses. Selected experiments performed in primary murine cardiomyocytes confirmed data obtained in HL-1 cells namely that the intrinsic and extrinsic apoptotic cascades are activated via DP2/MAPK/TNFα signaling.

Conclusions

We conclude that the reactive α,β-unsaturated carbonyl group of 15d-PGJ₂ is responsible for the pronounced upregulation of TNFα promoting cardiomyocyte apoptosis. We propose that inhibition of DP2 receptors could provide a possibility to modulate 15d-PGJ₂-induced myocardial injury.

Simvastatin activates the PPARγ-dependent pathway to prevent left ventricular hypertrophy associated with inhibition of RhoA signaling

Left ventricular hypertrophy is an independent risk factor for major adverse cardiovascular events. Statins have positive effects on this condition; however, the mechanisms are incompletely understood. In this study, we examined whether the effect of simvastatin on left ventricular hypertrophy can be mediated with the peroxisome proliferator-activated receptor (PPAR)γ-dependent pathway in rabbits with nonischemic heart failure (HF). We induced aortic insufficiency and constriction in 48 rabbits and divided them equally into control, HF, and HF with simvastatin therapy (HF-SIM) groups. The HF-SIM group was given 10 mg/kg/d of simvastatin. We echocardiographically measured baseline and 8-week cardiac structure and function, and we used Western blot, polymerase chain reaction, and electrophoretic analytic techniques to evaluate messenger RNA expression and protein expression and activity. In comparison with the HF group, the HF-SIM rabbits had an increased ejection fraction and decreased left ventricular mass index, interventricular septal thickness, ventricular posterior-wall thickness, and collagen volume fraction. Moreover, the messenger RNA and protein expression of PPARγ in the HF-SIM rabbits were significantly higher than those in the HF rabbits; and the activity and expression of nuclear factor-κB subunit p65, RhoA, and Rho GTPase were significantly lower. Our results indicate that simvastatin therapy attenuates the PPARγ-dependent pathway in association with the inhibition of RhoA and Rho GTPase signaling to inhibit nuclear factor-κB activation, thus preventing the development of left ventricular hypertrophy and fibrosis in rabbits with nonischemic heart failure.

Pioglitazone improves in vitro viability and function of endothelial progenitor cells from individuals with impaired glucose tolerance

Background

Evidence suggests that the PPARγ-agonist insulin sensitizer pioglitazone, may provide potential beneficial cardiovascular (CV) effects beyond its anti-hyperglycaemic function. A reduced endothelial progenitor cell (EPC) number is associated with impaired glucose tolerance (IGT) or diabetes, conditions characterised by increased CV risk.

Aim

To evaluate whether pioglitazone can provide benefit in vitro in EPCs obtained from IGT subjects.

Materials and Methods

Early and late-outgrowth EPCs were obtained from peripheral blood mononuclear cells of 14 IGT subjects. The in vitro effect of pioglitazone (10 µM) with/without PPARγ-antagonist GW9662 (1 µM) was assessed on EPC viability, apoptosis, ability to form tubular-like structures and pro-inflammatory molecule expression.

Results

Pioglitazone increased early and late-outgrowth EPC viability, with negligible effects on apoptosis. The capacity of EPCs to form tubular-like structures was improved by pioglitazone in early (mean increase 28%; p = 0.005) and late-outgrowth (mean increase 30%; p = 0.037) EPCs. Pioglitazone reduced ICAM-1 and VCAM-1 adhesion molecule expression in both early (p = 0.001 and p = 0.012 respectively) and late-outgrowth (p = 0.047 and p = 0.048, respectively) EPCs. Similarly, pioglitazone reduced TNFα gene and protein expression in both early (p = 0.034;p = 0.022) and late-outgrowth (p = 0.026;p = 0.017) EPCs compared to control. These effects were prevented by incubation with the PPARγ-antagonist GW9662.

Conclusion

Pioglitazone exerts beneficial effects in vitro on EPCs isolated from IGT subjects, supporting the potential implication of pioglitazone as a CV protective agents.

Identification of potential target genes of cardioprotection against ischemia-reperfusion injury by express sequence tags analysis in rat hearts

BACKGROUND

Ischemic preconditioning (IPC) is a powerful mechanism for limiting myocardial infarction during or after ischemia-reperfusion (IR) injury. However, effective target genes and proteins for IPC are unknown. We characterized global changes in gene expression in the heart during IR, and identified effective target genes for IPC.

METHODS

Hearts were isolated from Sprague-Dawley rats under control, IR, and IPC conditions. We generated expressed-sequence-tags (ESTs) for each group and investigated their functions and the major biological processes in which they are involved using the eukaryotic clusters of orthologous groups (KOG) database and bioinformatics analysis tools.

RESULTS

IR modified the expression of 126 genes. Of these, 62 were upregulated, 64 were downregulated, and 77 were found to be effective target genes for IPC. In KOG analysis, most of the genes whose expression was modified were involved in energy production and conversion and the cytoskeleton. A gene-to-gene interaction map revealed that IR modified the expression of genes in four major functional modules: electron transport chain/oxidative phosphorylation; tricarboxylic acid cycle/glucose metabolism/amino acid metabolism; cellular structure and contraction; and gene transcription, translation, and protein folding. At the individual gene level, the genes encoding mitochondrial cytochrome c oxidase subunits 2 and 3 were downregulated, and those encoding the major cytoskeleton components tropomyosin, myosin light chain, myomesin 2, and myosin regulatory light chain 2, as well as the gene encoding the iron-storage protein ferritin, were upregulated, and thus were identified as potential target genes. Real time PCR evaluated expression patterns of three mitochondrial IPC effective genes. Two-dimensional electrophoresis proteomic analyses revealed altered expression of 14 target proteins. The expression patterns of six proteins matched the corresponding EST expression patterns.

CONCLUSION

The global profiling of cardiac ischemia-related genes provides the possible mechanisms of IR and IPC and ways of treating IR injury.

Enhanced effects of cigarette smoke extract on inflammatory cytokine expression in IL-1β-activated human mast cells were inhibited by Baicalein via regulation of the NF-κB pathway

Background

Human mast cells are capable of a wide variety of inflammatory responses and play a vital role in the pathogenesis of inflammatory diseases such as allergy, asthma, and atherosclerosis. We have reported that cigarette smoke extract (CSE) significantly increased IL-6 and IL-8 production in IL-1β-activated human mast cell line (HMC-1). Baicalein (BAI) has anti-inflammatory properties and inhibits IL-1β- and TNF-α-induced inflammatory cytokine production from HMC-1. The goal of the present study was to examine the effect of BAI on IL-6 and IL-8 production from CSE-treated and IL-1β-activated HMC-1.

Methods

Main-stream (Ms) and Side-stream (Ss) cigarette smoke were collected onto fiber filters and extracted in RPMI-1640 medium. Two ml of HMC-1 at 1 × 10⁶ cells/mL were cultured with CSE in the presence or absence of IL-1β (10 ng/mL) for 24 hrs. A group of HMC-1 cells stimulated with both IL-1β (10 ng/ml) and CSE was also treated with BAI. The expression of IL-6 and IL-8 was assessed by ELISA and RT-PCR. NF-κB activation was measured by electrophoretic mobility shift assay (EMSA) and IκBα degradation by Western blot.

Results

Both Ms and Ss CSE significantly increased IL-6 and IL-8 production (p < 0.001) in IL-1β-activated HMC-1. CSE increased NF-κB activation and decreased cytoplasmic IκBα proteins in IL-1β-activated HMC-1. BAI (1.8 to 30 μM) significantly inhibited production of IL-6 and IL-8 in a dose-dependent manner in IL-1β-activated HMC-1 with the optimal inhibition concentration at 30 μM, which also significantly inhibited the enhancing effect of CSE on IL-6 and IL-8 production in IL-1β-activated HMC-1. BAI inhibited NF-κB activation and increased cytoplasmic IκBα proteins in CSE-treated and IL-1β-activated HMC-1.

Conclusions

Our results showed that CSE significantly increased inflammatory cytokines IL-6 and IL-8 production in IL-1β-activated HMC-1. It may partially explain why cigarette smoke contributes to lung and cardiovascular diseases. BAI inhibited the production of inflammatory cytokines through inhibition of NF-κB activation and IκBα phosphorylation and degradation. This inhibitory effect of BAI on the expression of inflammatory cytokines induced by CSE suggests its usefulness in the development of novel anti-inflammatory therapies.

Antioxidant properties of pioglitazone limit nicotinamide adenine dinucleotide phosphate hydrogen oxidase and augment superoxide dismutase activity in cardiac allotransplantation

BACKGROUND

Many non-immunologic factors contribute to the development of cardiac allograft vasculopathy (CAV), chief among them being ischemia-reperfusion injury associated with oxidative stress. We hypothesized that pioglitazone, a peroxisome proliferator-activated receptor (PPAR)-γ agonist, could attenuate graft oxidant stress in cardiac transplantation.

METHODS

Experiments were performed using a murine heterotopic cardiac allotransplantation model. Pioglitazone was administered to recipients once daily, beginning 1 day before transplantation.

RESULTS

At 4 hours after transplantation, pioglitazone significantly reduced the expression of endothelial cell adhesion receptors and infiltration of polymorphonuclear leukocytes (PMNs). The anti-oxidant balance in pioglitazone-treated cardiac allografts was significantly bolstered by reduced nicotinamide adenine dinucleotide phosphate hydrogen (NADPH) oxidase (Nox1 and p22(phox) sub-units) activity and preservation of manganese superoxide dismutase (SOD) activity, resulting in the mitigation of oxidative damage at the level of lipids, proteins, and DNA. At 7 days after transplantation, PPAR-γ was significantly up-regulated by pioglitazone, but nuclear factor-κB and inducible nitric oxide synthase were significantly down-regulated. A concomitant reduction of inflammatory cytokines and chemokines and graft leukosequestration was noted. Pioglitazone consequently prolonged cardiac allograft survival and attenuated CAV development. In vitro experiments demonstrated that pioglitazone decreased transendothelial PMN migration, NADPH oxidase activity, and loss of SOD activity in PMNs and endothelial cells.

CONCLUSIONS

Pioglitazone can suppress the oxidative stress and damage and can stimulate antioxidant capacity in cardiac allografts after transplantation. Mitigation of graft oxidant stress could be an important mechanism through which pioglitazone confers benefit after cardiac transplantation.

15-Deoxy-Δ¹²,¹⁴-prostaglandin J₂, an electrophilic lipid mediator of anti-inflammatory and pro-resolving signaling

15-deoxy-Δ(12,14)-prostagandin J(2) (15d-PGJ2) is produced in the inflamed cells and tissues as a consequence of upregulation of cyclooxygenase-2 (COX-2). 15d-PGJ2 is known to be the endogenous ligand of peroxisome proliferator-activated receptor gamma (PPARγ) with multiple physiological properties. Though one of the terminal products of the COX-2-catalyzed reactions, this cyclopentenone prostaglandin exerts potent anti-inflammatory actions, in part, by antagonizing the activities of pro-inflammatory transcription factors, such as NF-κB, STAT3, and AP-1, while stimulating the anti-inflammatory transcription factor Nrf2. These effects are not necessarily dependent on its activation of PPARγ, but often involves direct interaction with the above signaling molecules and their regulators. The locally produced 15d-PGJ2 is also involved in the resolution of inflammatory responses. Thus, 15d-PGJ2, especially formed during the late phase of inflammation, might inhibit cytokine secretion and other events by antigen-presenting cells like dendritic cells or macrophages. 15d-PGJ2 can also affect the priming and effector functions of T lymphocytes and induce their apoptotic cell death. These represent a negative feedback explaining how once-initiated immunologic and inflammatory responses are switched off and terminated. In this context, 15d-PGJ2 and its synthetic derivatives have therapeutic potential for the treatment of inflammatory disorders.

Multiple Interactions between Peroxisome Proliferators-Activated Receptors and the Ubiquitin-Proteasome System and Implications for Cancer Pathogenesis

The peroxisome proliferator-activated receptors (PPAR) α, β/δ, and γ are ligand-activated nuclear receptors involved in a number of physiological processes, including lipid and glucose homeostasis, inflammation, cell growth, differentiation, and death. PPAR agonists are used in the treatment of human diseases, like type 2 diabetes and dyslipidemia, and PPARs appear as promising therapeutic targets in other conditions, including cancer. A better understanding of the functions and regulation of PPARs in normal and pathological processes is of primary importance to devise appropriate therapeutic strategies. The ubiquitin-proteasome system (UPS) plays an important role in controlling level and activity of many nuclear receptors and transcription factors. PPARs are subjected to UPS-dependent regulation. Interestingly, the three PPAR isotypes are differentially regulated by the UPS in response to ligand-dependent activation, a phenomenon that may be intrinsically connected to their distinct cellular functions and behaviors. In addition to their effects ongene expression, PPARs appear to affect protein levels and downstream pathways also by modulating the activity of the UPS in target-specific manners. Here we review the current knowledge of the interactions between the UPS and PPARs in light of the potential implications for their effects on cell fate and tumorigenesis.

Telmisartan ameliorates experimental autoimmune myocarditis associated with inhibition of inflammation and oxidative stress

Excess cytokine produced by inflammatory stimuli contributes to the progression of myocardial damage in myocarditis. Angiotensin-II has been shown to play a pivotal role in the pathophysiology of various organs, especially the cardiovascular system. Some angiotensin II type 1 receptor antagonists are reported to inhibit proinflammatory cytokine production in vitro and in vivo. We investigated whether telmisartan, an angiotensin II type 1 receptor antagonist protects against experimental autoimmune myocarditis by suppression of inflammatory cytokines and oxidative stress. Experimental autoimmune myocarditis was induced in Lewis rats by immunization with porcine cardiac myosin. The rats were divided into two groups and treated with either telmisartan (10mg/kg/day) or vehicle for 21days. Age-matched normal rats without immunization were also included in this study. Myocardial functional parameters were significantly improved by treatment with telmisartan compared with vehicle-treated rats. Increased myocardial mRNA expressions of inflammatory cytokines [interleukin (IL-6), IL-1β, tumor necrosis factor-α and interferon-γ] were also suppressed by telmisartan treatment compared with vehicle-treated rats. Myocardial protein expressions of NADPH oxidase subunits p47phox, Nox-4, and gp91phox, myocardial levels of 8-hydroxydeoxyguanosine and 4-hydroxy-2-nonenal, and myocardial apoptosis were also significantly decreased by telmisartan treatment compared with vehicle-treated rats. Further, telmisartan significantly decreased endoplasmic reticulum stress markers in experimental autoimmune myocarditis rats. These findings suggest that telmisartan protects against experimental autoimmune myocarditis in rats, at least in part by suppressing inflammatory cytokines and oxidative stress; however, further investigations are needed before clinical use.

Anti-inflammatory effect of Guan-Xin-Er-Hao via the nuclear factor-kappa B signaling pathway in rats with acute myocardial infarction

A traditional Chinese medicine, Guan-Xin-Er-Hao (GXEH), is a famous multiple target therapeutic polypharmaceutical. Our aim was to evaluate whether or not oral administration of GXEH has an anti-inflammatory effect associated with blockade of nuclear factor-kappa B (NF-kappaB), and to investigate the NF-kappaB-mediated pro-inflammatory cytokines expression pathway during acute myocardial infarction (AMI) in rats. Sprague-Dawley rats were randomly assigned to four groups: oral GXEH administered at 15 or 5 g/kg, the vehicle control and sham-operated groups. Thirty minutes after giving GXEH or 0.9% NaCl (p.o.) once, coronary arteries were occluded except for the sham-operated rats. We measured 24-h infarct size, 3-h expression of NF-kappaB protein in the myocardial left ventricular tissues and serum levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and C-reactive protein (CRP). Compared with rats receiving vehicle, rats administered 15 g/kg GXEH had significantly reduced 24-h infarct size, expression of NF-kappaB protein and serum concentrations of TNF-alpha, IL-6, and CRP. GXEH at 5 g/kg did not have a significant effect on these parameters. In conclusion, GXEH exhibited an anti-inflammatory effect through inhibition of the NF-kappaB-mediated signaling pathway leading to downregulation of pro-inflammatory cytokine expression. These findings provide new evidence of the cardioprotective effect of GXEH through reduction of infarct size by mediating lots of endogenous materials via multiple pathways to act on myocardial cells in the treatment of cardiovascular disease.

Telmisartan, an angiotensin-II receptor blocker ameliorates cardiac remodeling in rats with dilated cardiomyopathy

Multiple trials over the past several years have examined indications for angiotensin receptor blockers (ARBs) in the treatment of left ventricular (LV) dysfunction, both acutely after myocardial infarction and in chronic heart failure (CHF). However, the effects of telmisartan, an ARB in rats with CHF after experimental autoimmune myocarditis (EAM) have not yet been analyzed. CHF was elicited in Lewis rats by immunization with cardiac myosin, and 28 days after immunization, the surviving Lewis rats were divided into two groups and treated with either telmisartan (10 mg kg(-1) day(-1)) or vehicle. After 4 weeks of treatment, we analyzed the effects of telmisartan on cardiac function, proinflammatory cytokines and cardiac remodeling in EAM rats. Myocardial functional parameters measured by hemodynamic and echocardiographic studies were significantly improved by telmisartan treatment in rats with CHF compared with those of vehicle-treated rats with CHF. Telmisartan significantly reduced levels of cardiac fibrosis, hypertrophy and its marker molecules (LV mRNA expressions of transforming growth factor beta 1, collagen I and III, and atrial natriuretic peptide), and peroxisome proliferator-activated receptor--gamma protein expression compared with those of vehicle-treated rats. CHF-induced increases in myocardial mRNA expressions of proinflammatory cytokines, (interleukin (IL)-6, IL-1beta), monocyte chemoattractant protein-1 and matrix metalloproteinases (MMP-2 and -9) were also suppressed by the treatment with telmisartan. Moreover, the plasma level of angiotensin-II was significantly elevated in telmisartan-treated rats. Our results indicate that telmisartan treatment significantly improved LV function and ameliorated the progression of cardiac remodeling in rats with CHF after EAM.

Evidence of anti-inflammatory effects of pioglitazone in the murine pleurisy model induced by carrageenan

Several studies have shown that the anti-inflammatory effect of Pioglitazone extends beyond the cardiovascular system. This study examines the anti-inflammatory effect of Pioglitazone in comparison to reference drugs (Dexamethasone and Indomethacin) in the mouse model of pleurisy induced by carrageenan which is characterized by two distinct phases (4 and 48 h) of inflammation. Pioglitazone (20 and 50 mg/kg, i.p., 0.5 h before pleurisy) inhibited both neutrophil (4 h) and mononuclears (48 h) influxes (P<0.01), but not exudation (P>0.05). While one dose of Pioglitazone was effective in inhibiting inflammation at 4 h, additional doses (10 or 20 mg/kg, i.p., 0.5 h before pleurisy induction followed by either a second dose at 24 h after the first one or two further doses at 12 h of time interval after the first one) were necessary to elicit inhibition of the second (48 h) inflammation phase. These effects were associated with a marked decrease in adenosine-deaminase (ADA) activity, tumor necrosis factor-alpha (TNF-alpha) and interleukin 1-beta (IL-1beta) levels (P<0.01). Myeloperoxidade (MPO) activity was inhibited only at 4 h (P<0.05). By contrast, reference drugs were able to inhibit all the studied inflammatory parameters (P<0.05). These results demonstrated an interesting anti-inflammatory property of this thiazolidinedione class and strengthen prior evidence that PPAR pathways constitute another important route of inflammatory process inhibition of this pleurisy model.

Is the Fas/Fas-L pathway a promising target for treating inflammatory heart disease?

The elucidation of the intricate molecular network of costimulus and regulatory pathways of the immune system led to the design of molecular therapies that specifically inactivate some cellular responses and ameliorate some autoimmune and inflammatory diseases. This innovative concept opens a new class of therapies, and one of the central components that could be targeted in future molecular therapies is the Fas-based pathway. Both soluble and membrane-bound Fas and Fas-L molecules exert a wide range of proinflammatory functions through the secretion of cytokines and chemokines, cellular chemotaxis, transcriptional regulation, cellular death, and others. Accordingly, many chronic inflammatory diseases, including myocarditis, are attenuated in mice lacking either molecule. Although it is tempting to speculate that the Fas/Fas-L pathway could be targeted for in vivo myocarditis therapy, the plurality of Fas/Fas-L functions can be an obstacle, leading to important side effects. In this review, we suggest that the injection of nonagonistic antibodies raised against the Fas molecule or the inactivation of downstream Fas-1,4,5-inositol triphosphate cascade are possible targets for myocarditis treatment.

Molecular diagnosis of the viral component in cardiomyopathies: pathophysiological, clinical and therapeutic implications

BACKGROUND

Myocarditis is defined as the inflammation of myocardium associated with cardiac dysfunction. Despite this clear-cut definition, diagnosis and etiologic treatment continue to create considerable debate. Viral infections are frequent causes of myocarditis and there is evidence that persistent viral infection is associated with poor prognosis in different subtypes of cardiomyopathy.

OBJECTIVE

To review methods for diagnosis of viral myocarditis and present the use of polymerase chain reaction (PCR)-based protocols for evaluating viral infection in myocarditis/cardiomyopathies.

METHODS

A review of published literature.

RESULTS/CONCLUSION

There is increasing evidence that PCR-based protocols can provide reliable molecular evidence for the presence of viral infection in myocardium. Thus application of molecular techniques will allow collection and analysis of more information on the epidemiology of viral cardiomyopathies, patient risk stratification and appropriate medical treatment.

Novel therapeutic targets in viral myocarditis

Viral myocarditis is an elusive infection of the heart that is currently without an effective or definitive treatment. Viral myocarditis has a complex disease progression that can be divided into early, middle and late phases. Direct cytopathic injury, apoptosis, activation of the innate and adaptive immune system and cardiac remodeling have all been implicated in the pathogenesis of viral myocarditis. Novel treatment approaches are evolving at a rapid pace. The purpose of this review is to provide an update on current research focused on identifying potential treatment options for viral myocarditis.

Candesartan improves myocardial damage in obese mice with viral myocarditis and induces cardiac adiponectin

PURPOSE

To clarify the mechanism of the effects of angiotensin II receptor type 1 antagonist, candesartan, upon cardiac adiponectin in the combination of myocarditis with obesity, we examined obese KKAy mice with acute viral myocarditis treated by candesartan and investigated cardiac adiponectin regulation.

METHODS

Mice were divided into candesartan early treatment group (Can-early) receiving orally candesartan at daily dose of 10 mg/kg 7 days starting before viral inoculation and then 7 days; candesartan late treatment group (Can-late) or vehicle (Vehicle) receiving candesartan starting simultaneously with viral inoculation and then 7 days. Encephalomyocarditis virus was used to induce the acute viral myocarditis. Differences in myocardial damages, serum adiponectin and myocardial expression of adiponectin, tumor necrosis factor-alpha (TNF-alpha), CCAAT/enhancer binding proteinalpha (C/EBPalpha) and peroxisome proliferator-activated receptor gamma (PPAR-gamma) and nuclear factor-kappaB (NF-kappaB) mRNA among three groups were determined on days 0, 4 and 7 after viral inoculation.

RESULTS

Mice in Can-early and Can-late groups showed reduced myocardial necrosis and cellular infiltration as compared with those in the Vehicle. On day 4 the circulating adiponectin levels were significantly higher in Can-early than those in Vehicle. Mice in Vehicle had significantly reduced in myocardial adiponectin mRNA after viral myocarditis. Cardiac adiponectin mRNA was significantly higher in Can-early and in Can-late than in Vehicle on days 4 and 7. Cardiac C/EBPalpha in Can-early and Can-early groups was significantly increased on day 4. Myocardial NF-kappaB and TNF-alpha mRNA in Can-early and Can-late groups were significantly reduced on day 7.

CONCLUSION

Candesartan treatment improved myocardial injury in obese mice with acute viral myocarditis and induced expression of cardiac adiponectin with the induction of C/EBPalpha as well as the reduction of cardiac NF-kappaB and TNF-alpha.

Baicalein inhibits IL-1beta- and TNF-alpha-induced inflammatory cytokine production from human mast cells via regulation of the NF-kappaB pathway

Background

Human mast cells are multifunctional cells capable of a wide variety of inflammatory responses. Baicalein (BAI), isolated from the traditional Chinese herbal medicine Huangqin (Scutellaria baicalensis Georgi), has been shown to have anti-inflammatory effects. We examined its effects and mechanisms on the expression of inflammatory cytokines in an IL-1β- and TNF-α-activated human mast cell line, HMC-1.

Methods

HMC-1 cells were stimulated either with IL-1β (10 ng/ml) or TNF-α (100 U/ml) in the presence or absence of BAI. We assessed the expression of IL-6, IL-8, and MCP-1 by ELISA and RT-PCR, NF-κB activation by electrophoretic mobility shift assay (EMSA), and IκBα activation by Western blot.

Results

BAI (1.8 to 30 μM) significantly inhibited production of IL-6, IL-8, and MCP-1 in a dose-dependent manner in IL-1β-activated HMC-1. BAI (30 μM) also significantly inhibited production of IL-6, IL-8, and MCP-1 in TNF-α-activated HMC-1. Inhibitory effects appear to involve the NF-κB pathway. BAI inhibited NF-κB activation in IL-1β- and TNF-α-activated HMC-1. Furthermore, BAI increased cytoplasmic IκBα proteins in IL-1β- and TNF-α-activated HMC-1.

Conclusion

Our results showed that BAI inhibited the production of inflammatory cytokines through inhibition of NF-κB activation and IκBα phosphorylation and degradation in human mast cells. This inhibitory effect of BAI on the expression of inflammatory cytokines suggests its usefulness in the development of novel anti-inflammatory therapies.

Peroxisome proliferator-activated receptor-gamma agonists as potential anti-inflammatory agents in asthma and chronic obstructive pulmonary disease

Inhaled corticosteroids are the most effective therapy for chronic persistent asthma and have a role in the treatment of chronic obstructive pulmonary disease (COPD). However, corticosteroids have reduced efficacy in some patients with asthma and fail to halt the progressive deterioration in lung function characteristic of COPD. Additional or alternative drug treatments to corticosteroids are required to improve control of inflammation in patients with therapy resistant airway disease. Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonists have displayed potent anti-inflammatory properties in experimental models of asthma and other airway diseases and as a result have the potential to become an additional treatment for asthma and COPD. We review the evidence from these experimental models and their applicability to asthma and COPD and the requirements for future clinical and experimental research.

Myocarditis

Myocarditis represents a heterogeneous final common pathway for myocardial inflammation of diverse etiologies and accounts for up to one-third of cases of dilated cardiomyopathy. The pathophysiology of viral myocarditis can be disaggregated into the effects of direct viral mediated injury, triggered acute and chronic autoimmune responses, and subsequent adverse remodeling. Recent research highlights the pathogenic role of persistent viral genome expression, Fas-ligand, tumor necrosis factor-alpha receptor 1, and antimyosin autoantibodies in the evolution of chronic systolic and diastolic heart failure. Recent refinements in endomyocardial biopsy evaluation, cardiac magnetic resonance imaging, and cytokine assays augment existing diagnostic modalities. Novel specific immunosuppressive targets aimed at interrupting myocyte injury and apoptosis, including interferon-beta seem promising to date in small clinical studies performed on selected patients.

Activation of immune and inflammatory systems in chronic heart failure: novel therapeutic approaches

Despite extensive research and novel treatments, chronic heart failure (CHF) remains a cause of high morbidity and mortality. Mounting evidence suggested that immune activation and inflammation play critical roles in the pathogenesis of CHF. In this review, we examine the current evidence regarding this contemporary pathophysiological mechanism, and evaluate the effects of conventional and novel cardiovascular drugs, such as calcium sensitisers and statins, on the immune and inflammatory mediator's network. Although therapies, which specifically antagonise tumour necrosis factor-alpha have not demonstrated considerable benefit in patients with CHF, there is an increasing evidence to suggest greater value from non-specific anti-inflammatory approaches, including: pentoxifylline, intravenous immunoglobulin, immune modulation therapy, growth hormones, physical training and nutrition regulation. Several innovative therapeutic targets, such as peroxisome proliferator-activated receptor gamma activators, Rho-kinase, p38 mitogen-activated protein kinase, nuclear transcription factor NF-kappaB, recovering or augmenting parasympathetic tone, cardiac resynchronisation therapy, macrophage inhibitors and chemokine receptor antagonists, are briefly discussed in this review. While we have recently demonstrated the potential merits of combining low-dose methotrexate with conventional therapy, through extensively modulating the activated immune and inflammatory mediator's network, there is a need for further rigorous research of this complex network, especially involving current promising therapies which modulate this system. Such evidence has the potential to revolutionise changes for the management of this disorder. Based on the 'heterogeneity' of immune activation and inflammation among different CHF populations, an 'optimised combination treatment' may offer exciting benefits for individual therapy in the future.

Effect of pioglitazone, a peroxisome proliferator-activated receptor gamma agonist, on ischemia-reperfusion injury in rats

Two groups of rats were used to examine the effect of pioglitazone, a peroxisome proliferator-activated receptor gamma (PPARgamma) agonist, on rat hearts using an in vivo model of ischemia-reperfusion (I/R) to elucidate potential mechanisms. One group was the 30-min reperfusion group, which was further subdivided into sham (n=5), vehicle (n=6) and pioglitazone (3 mg x kg(-1), n=7) treatment groups with 30 min ischemia followed by 30 min reperfusion to detect data related to cardiac function and the area of myocardial infarction. The other group was the 120-min reperfusion group, subdivided into sham (n=5), vehicle (n=6), and pioglitazone 0.3 mg x kg(-1) (n=6), 1 mg x kg(-1) (n=7) and 3 mg x kg(-1) (n=6) treatment groups. Immunohistochemistry, in situ hybridization, terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) and DNA agarose gel electrophoresis were performed to detect apoptosis and expressions of Bax, Bcl-2, caspase 3, MMP-2 and PPARgamma protein, and MMP-2 and PPARgamma mRNA. We found that, after acute treatment with pioglitazone, the ratio of necrosis to area at risk decreased by 28% (p<0.01) and that of necrosis to left ventricle was reduced by 32% (p<0.01), compared with the vehicle group. Heart rate and +dp/dt(max), representing the cardiac systolic function, as well as -dp/dt(max), the indicator of cardiac diastolic function, improved significantly at 1 and 30 min after reperfusion (p<0.05-0.01). Furthermore, myocardial apoptosis was significantly suppressed by acute treatment with pioglitazone as evidenced by the decreased number of TUNEL-positive myocytes and DNA ladder, enhanced Bcl-2 protein expression, reduced Bax and caspase 3 protein expression in a dose-dependent manner compared with vehicle-treated rats. In addition, acute treatment with pioglitazone dose-dependently increased PPARgamma expression and decreased MMP-2 expression at protein and mRNA levels. Our findings demonstrate that a PPARgamma agonist may protect the heart from I/R injury. The protective effect is likely to occur by reducing cardiomyocyte apoptosis and inhibiting MMP-2.

Peroxisome proliferator-activated receptor-gamma agonist is protective in podocyte injury-associated sclerosis

We have previously observed increased expression of peroxisome proliferator-activated receptor gamma (PPARgamma) in podocytes in both rat and human sclerotic conditions. The aim of the present study was to investigate whether activation of PPARgamma can attenuate podocyte injury-associated glomerulosclerosis in vivo. Puromycin aminonucleoside nephropathy was induced in Sprague-Dawley rats. The animals then either received no further treatment (control group (CONT)); or the PPARgamma agonist, pioglitazone (Pio) starting at week 0 (P0); or Pio starting at week 6 (P6), with sacrifice at week 12. At week 12, urinary protein excretion and systolic blood pressure were similar in the three groups. Glomerular filtration rate and glomerulosclerosis were decreased in CONT and P0 at week 12, but preserved in P6 rats. PPARgamma expression in CONT at 12 weeks was increased in podocytes and in mesangial WT-1 cells in segmentally sclerotic glomeruli, with less Wilms' tumor 1 (WT-1) staining. In P6 rats, mesangial WT-1 staining was lessened, but podocyte staining was strongly accentuated. Delayed treatment with Pio partially restored podocyte staining and tended to decrease the ratio of proliferating cell nuclear antigen-positive to apoptotic cells in glomeruli. Both treatment groups showed significantly reduced infiltrating glomerular macrophages and plasminogen activator inhibitor-1 mRNA expression in cortex, with no change in transforming growth factor-beta1 and tissue inhibitor of metalloproteinase-1 mRNA. Pio also decreased renal cortical angiopoietin-like protein 4 expression to almost 20% of CONT group, associated with increased vascular endothelial-derived growth factor expression in glomeruli. We conclude that treatment with PPARgamma agonist has protective effects on progression of glomerulosclerosis.

Inflammation and immune regulation by 12/15-lipoxygenases

12/15-Lipoxygenases (12/15-LOX) are members of the LOX family, which are expressed in mammals by monocytes and macrophages following induction by the T helper type 2 cytokines, interleukins-4 and -13. They oxygenate free polyenoic fatty acids but also ester lipids and even complex lipid-protein assemblies such as biomembranes and lipoproteins. The primary oxidation products are either reduced by glutathione peroxidases to corresponding hydroxy derivatives or metabolized into secondary oxidized lipids including leukotrienes, lipoxins and hepoxilins, which act as lipid mediators. Examination of knockout and transgenic animals revealed important roles for 12/15-LOX in inflammatory diseases, including atherosclerosis, cancer, osteoporosis, angiotension II-dependent hypertension and diabetes. In vitro studies suggested 12/15-LOX products as coactivators of peroxisomal proliferator activating-receptors (PPAR), regulators of cytokine generation, and modulators of gene expression related to inflammation resolution. Despite much work in this area, the biochemical mechanisms by which 12/15-LOX regulates physiological and pathological immune cell function are not fully understood. This review will summarize the biochemistry and tissue expression of 12/15-LOX and will describe the current knowledge regarding its immunobiology and regulation of inflammation.

The emerging functions of UCP2 in health, disease, and therapeutics

The uncoupling proteins (UCPs) are attracting an increased interest as potential therapeutic targets in a number of important diseases. UCP2 is expressed in several tissues, but its physiological functions as well as potential therapeutic applications are still unclear. Unlike UCP1, UCP2 does not seem to be important to thermogenesis or weight control, but appears to have an important role in the regulation of production of reactive oxygen species, inhibition of inflammation, and inhibition of cell death. These are central features in, for example, neurodegenerative and cardiovascular disease, and experimental evidence suggests that an increased expression and activity of UCP2 in models of these diseases has a beneficial effect on disease progression, implicating a potential therapeutic role for UCP2. UCP2 has an important role in the pathogenesis of type 2 diabetes by inhibiting insulin secretion in islet beta cells. At the same time, type 2 diabetes is associated with increased risk of cardiovascular disease and atherosclerosis where an increased expression of UCP2 appears to be beneficial. This illustrates that therapeutic applications involving UCP2 likely will have to regulate expression and activity in a tissue-specific manner.