KMUP-1 attenuates isoprenaline-induced cardiac hypertrophy in rats through NO/cGMP/PKG and ERK1/2/calcineurin A pathways

Xanthine derivative KMUP-1 ameliorates retinopathy

Retinal neovascularization (RNV) and cell apoptosis observed in retinopathy are the most common cause of vision loss worldwide. Increasing vascular endothelial growth factor (VEGF), which was driven by hypoxia or inflammation, would result in RNV. This study investigated the anti-inflammatory and anti-apoptotic xanthine-based derivative KMUP-1 on hypoxia-induced conditions in vitro and in vivo. In the oxygen-induced retinopathy animal model, KMUP-1 mitigated vaso-obliteration and neovascularization. In the cell model of hypoxic endothelium cultured at 1% O2, KMUP-1 inhibited endothelial migration and tube formation and had no cytotoxic effect on cell growth. Upregulation of pro-angiogenic factors, HIF-1α and VEGF, and pro-inflammatory cytokines, IL-1β and TNF-α, expression in the retinal-derived endothelial cells, RF/6 A cells, upon hypoxia stimulation, was suppressed by KMUP-1 treatment. RF/6 A cells treated with KMUP-1 showed a reduction of PI3K/Akt, ERK, and RhoA/ROCKs signaling pathways and induction of protective pathways such as eNOS and soluble guanylyl cyclase at 1% O2. Furthermore, KMUP-1 decreased the expression of VEGF, ICAM-1, TNF-α, and IL-1β and increased the BCL-2/BAX ratio in the oxygen-induced retinopathy mouse retina samples. In conclusion, the results of this study suggest that KMUP-1 has potential therapeutic value in retinopathy due to its triple effects on anti-angiogenesis, anti-inflammation, and anti-apoptosis in hypoxic endothelium.

Targeting macrophage polarization as a promising therapeutic strategy for the treatment of osteoarthritis

Osteoarthritis (OA) is a chronic osteoarthropathy characterized by the progressive degeneration of articular cartilage and synovial inflammation. Early OA clinical treatments involve intra-articular injection of glucocorticoids, oral acetaminophen and non-steroidal anti-inflammatory drugs (NSAIDs), which are used for anti-inflammation and pain relief. However, long-term use of these agents will lead to inevitable side effects, even aggravate cartilage loss. At present, there are no disease-modifying OA drugs (DMOADs) yet approved by regulatory agencies. Polarization regulation of synovial macrophages is a new target for OA treatment. Inhibiting M1 polarization and promoting M2 polarization of synovial macrophages can alleviate synovial inflammation, relieve joint pain and inhibit articular cartilage degradation, which is a promising strategy for OA treatment. In this study, we describe the molecular mechanisms of macrophage polarization and its key role in the development of OA. Subsequently, we summarize the latest progress of strategies for OA treatment through macrophage reprogramming, including small molecule compounds (conventional western medicine and synthetic compounds, monomer compounds of traditional Chinese medicine), biomacromolecules, metal/metal oxides, cells, and cell derivatives, and interprets the molecular mechanisms, hoping to provide some information for DMOADs development.

Xanthine Derivative KMUP-1 Attenuates Experimental Periodontitis by Reducing Osteoclast Differentiation and Inflammation

Periodontitis is an inflammatory disease of gum that may predispose to serious systemic complications such as diabetes and cardiovascular diseases. Activation of macrophages and osteoclasts around periodontal tissue can accelerate gum inflammation. In addition, alteration of cyclic nucleotide levels is associated with the severity of periodontitis. Our previous study has shown that KMUP-1, a xanthine derivative exhibiting phosphodiesterase inhibition and soluble guanylyl cyclase activation, can inhibit lipopolysaccharide (LPS)-induced inflammation and receptor activator of nuclear factor kappa-Β ligand (RANKL)-induced osteoclastogenesis. This study was aimed to investigate whether KMUP-1 could attenuate periodontitis both in vitro and in vivo. In vitro, the protective effect of KMUP-1 on inflammation and osteoclastogenesis was investigated in RANKL-primed RAW264.7 cells treated by Porphyromonas gingivalis LPS (PgLPS). The results showed that KMUP-1 attenuated PgLPS-induced osteoclast differentiation as demonstrated by decreased TRAP-positive multinuclear cells and TRAP activity. This reduction of osteoclast differentiation by KMUP-1 was reversed by KT5823, a protein kinase G inhibitor. Similarly, pro-inflammatory cytokine levels induced by PgLPS were inhibited by KMUP-1 in a dose-dependent manner whereas reversed by KT5823. Mechanistically, suppression of MAPKs, PI3K/Akt, and NF-κB signaling pathways and decrease of c-Fos and NFATc1 expression in osteoclast precursors by KMUP-1 may mediate its protective effect. In vivo, two models of periodontitis in rats were induced by gingival injections of PgLPS and ligature placement around molar teeth, respectively. Our results showed that KMUP-1 inhibited alveolar bone loss in both rat models, and this effect mediated at least partly by reduced osteoclastogenesis. In conclusion, our study demonstrated the therapeutic potential of KMUP-1 on periodontitis through suppression of inflammation and osteoclast differentiation.

Ellagic Acid Prevents Ca2+ Dysregulation and Improves Functional Abnormalities of Ventricular Myocytes via Attenuation of Oxidative Stress in Pathological Cardiac Hypertrophy

The aim of this study was to investigate whether ellagic acid (EA) treatment can prevent changes in contractile function and Ca2+ regulation of cardiomyocytes in pathologic cardiac hypertrophy. Groups were assigned as Con group; an ISO group in which the rats received isoproterenol alone (5 mg/kg/day); and an ISO + EA group in which the rats received isoproterenol and EA (20 mg/kg/day) for 4 weeks. Subsequently, fractional shortening, intracellular Ca2+ signals, and L-type Ca2+ currents of isolated ventricular myocytes were recorded. Protein expression levels were also determined by the Western blotting method. The survival rate was increased, and the upregulated cardiac hypertrophy markers were significantly attenuated with the EA treatment. The fractional shortening and relaxation rate of myocytes was decreased in the ISO group, whereas EA significantly improved these changes. Ventricular myocytes of the ISO + EA rats displayed lower diastolic Ca2+ levels, higher Ca2+ transients, shorter Ca2+ decay, and higher L-type Ca2+ currents than those of ISO rats. Protein expression analyses indicated that the upregulated p-PLB and p-CaMKII expressions were restored by EA treatment, suggesting improved calcium handling in the ISO + EA rat heart. Moreover, ISO rats displayed significantly increased expression of p-22phox and p47phox subunits of NOX2 protein. Expression of the p22phox subunit was reduced with EA administration, while the decrease in p47phox did not reach a significant level. The increased ROS impairs Ca2+ homeostasis and contractile activity of cardiac myocytes, whereas chronic EA administration prevents Ca2+ dysregulation and functional abnormalities associated with pathological cardiac hypertrophy via the diminution of oxidative stress.

In Vitro Evaluation of the Anti-Inflammatory Effect of KMUP-1 and In Vivo Analysis of Its Therapeutic Potential in Osteoarthritis

Osteoarthritis is a degenerative arthropathy that is mainly characterized by dysregulation of inflammatory responses. KMUP-1, a derived chemical synthetic of xanthine, has been shown to have anti-inflammatory and antioxidant properties. Here, we aimed to investigate the in vitro anti-inflammatory and in vivo anti-osteoarthritis effects of KMUP-1. Protein and gene expressions of inflammation markers were determined by ELISA, Western blotting and microarray, respectively. RAW264.7 mouse macrophages were cultured and pretreated with KMUP-1 (1, 5, 10 μM). The productions of TNF-α, IL-6, MMP-2 and MMP- 9 were reduced by KMUP-1 pretreatment in LPS-induced inflammation of RAW264.7 cells. The expressions of iNOS, TNF-α, COX-2, MMP-2 and MMP-9 were also inhibited by KMUP-1 pretreatment. The gene expression levels of TNF and COX families were also downregulated. In addition, KMUP-1 suppressed the activations of ERK, JNK and p38 as well as phosphorylation of IκBα/NF-κB signaling pathways. Furthermore, SIRT1 inhibitor attenuated the inhibitory effect of KMUP-1 in LPS-induced NF-κB activation. In vivo study showed that KMUP-1 reduced mechanical hyperalgesia in monoiodoacetic acid (MIA)-induced rats OA. Additionally, KMUP-1 pretreatment reduced the serum levels of TNF-α and IL-6 in MIA-injected rats. Moreover, macroscopic and histological observation showed that KMUP-1 reduced articular cartilage erosion in rats. Our results demonstrated that KMUP-1 inhibited the inflammatory responses and restored SIRT1 in vitro, alleviated joint-related pain and cartilage destruction in vivo. Taken together, KMUP-1 has the potential to improve MIA-induced articular cartilage degradation by inhibiting the levels and expression of inflammatory mediators suggesting that KMUP-1 might be a potential therapeutic agent for OA.

BKCa Channel Inhibition by Peripheral Nerve Injury Is Restored by the Xanthine Derivative KMUP-1 in Dorsal Root Ganglia

This study explored whether KMUP-1 improved chronic constriction injury (CCI)-induced BKCa current inhibition in dorsal root ganglion (DRG) neurons. Rats were randomly assigned to four groups: sham, sham + KMUP-1, CCI, and CCI + KMUP-1 (5 mg/kg/day, i.p.). DRG neuronal cells (L4-L6) were isolated on day 7 after CCI surgery. Perforated patch-clamp and inside-out recordings were used to monitor BKCa currents and channel activities, respectively, in the DRG neurons. Additionally, DRG neurons were immunostained with anti-NeuN, anti-NF200 and anti-BKCa. Real-time PCR was used to measure BKCa mRNA levels. In perforated patch-clamp recordings, CCI-mediated nerve injury inhibited BKCa currents in DRG neurons compared with the sham group, whereas KMUP-1 prevented this effect. CCI also decreased BKCa channel activity, which was recovered by KMUP-1 administration. Immunofluorescent staining further demonstrated that CCI reduced BKCa-channel proteins, and KMUP-1 reversed this. KMUP-1 also changed CCI-reduced BKCa mRNA levels. KMUP-1 prevented CCI-induced neuropathic pain and BKCa current inhibition in a peripheral nerve injury model, suggesting that KMUP-1 could be a potential agent for controlling neuropathic pain.

Paroxetine Attenuates Cardiac Hypertrophy Via Blocking GRK2 and ADRB1 Interaction in Hypertension

Background

ADRB1 (adrenergic receptor beta 1) responds to neuroendocrine stimulations, which have great implications in hypertension. GRK2 (G protein‐coupled receptor kinase 2) is an essential regulator for many G protein‐coupled receptors and subsequent cell signaling cascades, but its role as a regulator of ADRB1 and associated cardiac hypertrophy in hypertension remains to be elucidated.

Methods and Results

In this study, we found the expressions of GRK2 and ADRB1 in peripheral blood mononuclear cells were positively associated with blood pressure levels in hypertensive patients and with their expression in heart. In vitro evidence showed a direct interaction in ADRB1 and GRK2 and genetic depletion of GRK2 blocks epinephrine‐induced upregulation of hypertrophic and fibrotic genes in cardiomyocytes. Meanwhile, we discovered a selective serotonin reuptake inhibitor paroxetine specifically blockades GRK2 and ADRB1 interaction. In vivo, paroxetine treatment ameliorates hypertension‐induced cardiac hypertrophy, dysfunction, and fibrosis in animal models. We found that paroxetine suppressed sympathetic overdrive and increased the adrenergic receptor sensitivity to catecholamines. Paroxetine treatment also blocks epinephrine‐induced upregulation of hypertrophic and fibrotic genes as well as ADRB1 internalization in cardiomyocytes. Coadministration of paroxetine further potentiates metoprolol‐induced reductions in blood pressure and heart rate, further attenuating cardiac hypertrophy in spontaneously hypertensive rats. Furthermore, in patients with hypertension accompanied with depression, we observed that cardiac remodeling was less severe in those with paroxetine treatment compared with those with other types of anti‐depressive agents.

Conclusions

Paroxetine promotes ADRB1 sensitivity and attenuates cardiac hypertrophy partially via blocking GRK2‐mediated ADRB1 activation and internalization in the context of hypertension.

Advances in the Protective Mechanism of NO, H2S, and H2 in Myocardial Ischemic Injury

Myocardial ischemic injury is among the top 10 leading causes of death from cardiovascular diseases worldwide. Myocardial ischemia is caused mainly by coronary artery occlusion or obstruction. It usually occurs when the heart is insufficiently perfused, oxygen supply to the myocardium is reduced, and energy metabolism in the myocardium is abnormal. Pathologically, myocardial ischemic injury generates a large number of inflammatory cells, thus inducing a state of oxidative stress. This sharp reduction in the number of normal cells as a result of apoptosis leads to organ and tissue damage, which can be life-threatening. Therefore, effective methods for the treatment of myocardial ischemic injury and clarification of the underlying mechanisms are urgently required. Gaseous signaling molecules, such as NO, H₂S, H₂, and combined gas donors, have gradually become a focus of research. Gaseous signaling molecules have shown anti-apoptotic, anti-oxidative and anti-inflammatory effects as potential therapeutic agents for myocardial ischemic injury in a large number of studies. In this review, we summarize and discuss the mechanism underlying the protective effect of gaseous signaling molecules on myocardial ischemic injury.

Extracellular heat shock protein HSC70 protects against lipopolysaccharide-induced hypertrophic responses in rat cardiomyocytes

We have recently shown that exogenous administration of extracellular heat shock protein HSC70, a previously recognized intracellular chaperone protein, can protect against LPS-induced cardiac dysfunction through anti-inflammatory actions. However, whether it can also exert anti-hypertrophic effect is unknown. The present study was aimed to investigate the efficacy of HSC70 against cardiac hypertrophy and its underlying molecular mechanisms. Cardiomyocytes were isolated from the cardiac ventricles of neonatal Wistar rats and LPS (1 μg/mL) was used to induce the hypertrophic responses. We found that HSC70 (0.1, 1 and 5 μg/mL) pretreatment attenuated LPS-induced cardiomyocyte hypertrophy dose-dependently. In addition, HSC70 mitigated LPS-induced inflammatory mediators including TNF-α, IL-6, NO, iNOS and COX-2, with down-regulated protein expression of MMP-2 and MMP-9. Moreover, HSC70 repressed LPS-induced signaling of MAPK and Akt. Finally, HSC70 inhibited NF-κB subunit p65, and the DNA binding activity of NF-κB. Taken together, these findings suggest that in vitro HSC70 can exert anti-hypertrophic effects through inhibition of pro-inflammatory mediators, which are potential mediated by the down-regulation of MAPK, Akt and NF-κB signaling pathways. In conclusion, extracellular HSC70 may be a novel pharmacologic strategy in the management of cardiac hypertrophy.

KMUP-1 regulates the vascular calcification in chronic renal failure by mediating NO/cGMP/PKG signaling pathway

OBJECTIVE

To explore the potential mechanism of KMUP-1 in the vascular calcification of chronic renal failure (CRF) through mediating NO/cGMP/PKG pathway, and provide novel insights into the CRF treatment.

METHODS

CRF rats were treated by KMUP-1 with/without L-NNA (a NOS inhibitor) and then performed by ELISA, alizarin red staining, Von Kossa staining, Masson's trichrome, Sirius red staining and CD3 immunohistochemical staining. Simultaneously, vascular smooth muscle cells (VSMCs) were collected from rats to confirm the effect of KMUP-1 on vascular calcification in vitro via NO/cGMP/PKG pathway. Besides, protein and mRNA expressions were determined via Western blotting and qRT-PCR, respectively.

RESULTS

CRF rats were elevated in 24-h urine protein, blood urea nitrogen (BUN), serum creatinine, Cys-C levels and inflammatory cytokines. Besides, CRF rats also showed increased calcium content and ALP level with up-regulated mRNA of osteogenic differentiation-related markers. Furthermore, the up-regulated expressions of eNOS and PKG, as well as down-regulated levels of NOx and cGMP were also found in CRF rats. However, renal failure and vascular calcification of CRF were improved significantly by KMUP-1 treatment via activation of NO/cGMP/PKG pathway. Moreover, KMUP-1 treatment attenuated calcified VSMCs, accompanied by the decreases in the calcified nodules, level of calcium and activity of ALP. In addition, either L-NNA treatment for CRF rats or the calcified VSMCs could antagonize the improving effect of KMUP-1.

CONCLUSION

KMUP-1 can improve the renal function and vascular calcification in CRF rats at least in part by activating NO/cGMP/PKG pathway.

KMUP-1 Ameliorates Ischemia-Induced Cardiomyocyte Apoptosis through the NO⁻cGMP⁻MAPK Signaling Pathways

To test whether KMUP-1 (7-[2-[4-(2-chlorophenyl) piperazinyl]ethyl]-1,3-dimethylxanthine) prevents myocardial ischemia-induced apoptosis, we examined KMUP-1-treated H9c2 cells culture. Recent attention has focused on the activation of nitric oxide (NO)-guanosine 3’, 5’cyclic monophosphate (cGMP)-protein kinase G (PKG) signaling pathway triggered by mitogen-activated protein kinase (MAPK) family, including extracellular-signal regulated kinase 1/2 (ERK1/2), c-Jun N-terminal kinase (JNK), and p38 in the mechanism of cardiac protection during ischemia-induced cell-death. We propose that KMUP-1 inhibits ischemia-induced apoptosis in H9c2 cells culture through these pathways. Cell viability was assessed using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and apoptotic evaluation was conducted using DNA ladder assay and Hoechst 33342 staining. The level of intracellular calcium was detected using-Fura2-acetoxymethyl (Fura2-AM) staining, and mitochondrial calcium with Rhod 2-acetoxymethyl (Rhod 2-AM) staining under fluorescence microscopic observation. The expression of endothelium NO synthase (eNOS), inducible NO synthase (iNOS), soluble guanylate cyclase α1 (sGCα1), PKG, Bcl-2/Bax ratio, ERK1/2, p38, and JNK proteins were measured by Western blotting assay. KMUP-1 pretreatment improved cell viability and inhibited ischemia-induced apoptosis of H9c2 cells. Calcium overload both in the intracellular and mitochondrial sites was attenuated by KMUP-1 pretreatment. Moreover, KMUP-1 reduced intracellular reactive oxygen species (ROS), increased plasma NOx (nitrite and nitrate) level, and the expression of eNOS. Otherwise, the iNOS expression was downregulated. KMUP-1 pretreatment upregulated the expression of sGCα1 and PKG protein. The ratio of Bcl-2/Bax expression was increased by the elevated level of Bcl2 and decreased level of Bax. In comparison with the ischemia group, KMUP-1 pretreatment groups reduced the expression of phosphorylated extracellular signal-regulated kinases ERK1/2, p-p38, and p-JNK as well. Therefore, KMUP-1 inhibits myocardial ischemia-induced apoptosis by restoration of cellular calcium influx through the mechanism of NO-cGMP-MAPK pathways.

KMUP-1, a GPCR Modulator, Attenuates Triglyceride Accumulation Involved MAPKs/Akt/PPARγ and PKA/PKG/HSL Signaling in 3T3-L1 Preadipocytes

Xanthine-based KMUP-1 was shown to inhibit phosphodiesterases (PDEs) and modulate G-protein coupled receptors (GPCRs) to lower hyperlipidemia and body weight. This study further investigated whether KMUP-1 affects adipogenesis and lipolysis in 3T3-L1 preadipocytes. KMUP-1 (1–40 µM) concentration-dependently attenuated Oil Red O (ORO) staining and decreased triglyceride (TG) accumulation, indicating adipogenesis inhibition in 3T3-L1 cells. In contrast, the β-agonist ractopamine increased ORO staining and TG accumulation and adipogenesis. KMUP-1 (1–40 µM) also reduced MAPKs/Akt/PPARγ expression, PPARγ1/PPARγ2 mRNA, and p-ERK immunoreactivity at the adipogenesis stage, but enhanced hormone sensitive lipase (HSL) immunoreactivity at the lipolysis stage. Addition of protein kinase A (PKA) or protein kinase G (PKG) antagonist (KT5720 or KT5728) to adipocytes did not affect HSL immunoreactivity. However, KMUP-1 did increase HSL immunoreactivity and the effect was reduced by PKA or PKG antagonist. Simvastatin, theophylline, caffeine, and sildenafil, like KMUP-1, also enhanced HSL immunoreactivity. Phosphorylated HSL (p-HSL) was enhanced by KMUP-1, indicating increased lipolysis in mature 3T3-L1 adipocytes. Decreases of MAPKs/Akt/PPARγ during adipogenesis contributed to inhibition of adipocyte differentiation, and increases of PKA/PKG at lipolysis contributed to HSL activation and TG hydrolysis. Taken together, the data suggest that KMUP-1 can inhibit hyperadiposity in 3T3-L1 adipocytes.

KMUP-1 protects against streptozotocin-induced mesenteric artery dysfunction via activation of ATP-sensitive potassium channels

BACKGROUND

Diabetes mellitus is a metabolic disorder characterized by chronic hyperglycemia accompanied by impaired vascular and endothelial function. Activation of ATP-sensitive potassium (K_ATP) channels can protect endothelial function against hypertension and hyperglycemia. KMUP-1, a xanthine derivative, has been demonstrated to modulate K⁺-channel activity in smooth muscles. This study investigated protective mechanisms of KMUP-1 in impaired mesenteric artery (MA) reactivity in streptozotocin (STZ)-induced diabetic rats.

METHODS

Rats were divided into three groups: control, STZ (65 mg/kg, ip) and STZ + KMUP-1 (5 or 10 mg/kg/day, ip). MA reactivity was measured by dual wire myograph. MA smooth muscle cells (MASMCs) were enzymatically dissociated and the K_ATP currents recorded by a whole-cell patch-clamp technique.

RESULTS

STZ decreased MA K_ATP currents in a time-course dependent manner and achieved steady inhibition at day 14. In the MASMCs of STZ-treated rats, KMUP-1 partially recovered the K_ATP currents, suggesting that vascular K_ATP channels were activated by KMUP-1. K⁺ (80 mM KCl)-induced MA contractions in STZ-treated rats were higher than those of control rats. KMUP-1 significantly attenuated STZ-stimulated MA contractions in response to high K⁺, suggesting that KMUP-1 may partly restore the vascular reactivity of MAs. In addition, STZ decreased the expression of endothelial nitric oxide synthase (eNOS) and this effect was reversed by KMUP-1, suggesting that KMUP-1 could improve STZ-induced vascular endothelial dysfunction.

CONCLUSION

KMUP-1 prevents STZ impairment of MA reactivity, eNOS levels and K_ATP channels, and accordingly protects against vascular dysfunction in diabetic rats.

Molsidomine Attenuates Ventricular Electrical Remodeling and Arrhythmogenesis in Rats With Chronic β-Adrenergic Receptor Activation Through the NO/cGMP/PKG Pathway

This study investigated the effects and associated underlying mechanisms of molsidomine, a nitric oxide (NO) donor, on cardiac electrical remodeling and ventricular tachycardias (VTs) induced by chronic isoprenaline (ISO) stimulation in rats. The rats were randomly divided into groups that were treated with saline (control group), ISO (ISO group), ISO + molsidomine (ISO + M group), and ISO + molsidomine + the soluble guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, ISO + M + O group) for 14 days. An electrophysiological study was performed to assess cardiac repolarization, action potential duration restitution, and the induction of action potential duration alternans and VTs in vitro. The properties of the Ca transients, Ca handling-related proteins, and NO/guanosine 3'5'-cyclic monophosphate (cGMP)/protein kinase G (PKG) pathway were examined. Compared with the control group, chronic ISO stimulation prolonged the cardiac repolarization, decreased the Ca transient alternans and action potential duration alternans thresholds, and increased the maximum slope (Smax) of the action potential duration restitution curve and incidence of VTs in vitro. All these effects were attenuated by molsidomine treatment (P < 0.05). Moreover, molsidomine activated cGMP/PKG signaling and stabilized the expression of calcium handling-related proteins compared with the ISO group. However, the protective effects of molsidomine were partially inhibited by ODQ. Our results suggest that molsidomine stabilizes calcium handling and attenuates cardiac electrical remodeling and arrhythmogenesis in rats with chronic β-adrenergic receptor activation. These effects are at least partially mediated by the activation of NO/cGMP/PKG pathway.

KMUP-1 attenuates high glucose and transforming growth factor-β1-induced pro-fibrotic proteins in mesangial cells

We have previously demonstrated that KMUP-1, a xanthine-based nitric oxide enhancer, attenuates diabetic glomerulosclerosis, while increasing renal endothelial nitric oxide synthase expression in rats. However, the anti‑fibrotic mechanisms of KMUP‑1 treatment in diabetic nephropathy in terms of cell biology and transforming growth factor-β1 (TGF‑β1) remain unclear. Therefore, the present study involved investigating the effects of KMUP‑1 on high glucose (HG) or TGF‑β1‑induced pro‑fibrotic proteins in mouse mesangial (MES13) cells, and the effects of KMUP‑1 on streptozotocin (STZ)‑induced diabetic rats. It was identified that KMUP‑1 (10 µM) attenuated HG (30 mM)‑induced cell hypertrophy while attenuating TGF‑β1 gene transcription and bioactivity in MES13 cells. In addition, KMUP‑1 attenuated TGF‑β1 (5 ng/ml)‑induced Smad2/3 phosphorylation while attenuating HG or TGF‑β1‑induced collagen IV and fibronectin protein expression. Furthermore, KMUP‑1 attenuated HG‑decreased Suv39h1 and H3K9me3 levels. Finally, KMUP‑1 attenuated diabetes-induced collagen IV and fibronectin protein expression in STZ‑diabetic rats at 8 weeks. In conclusion, KMUP‑1 attenuates HG and TGF‑β1‑induced pro‑fibrotic proteins in mesangial cells and attenuation of TGF‑β1‑induced signaling and attenuation of HG‑decreased Suv39h1 expression may be two of the anti-fibrotic mechanisms of KMUP‑1.

Inhibition of the TGFβ signalling pathway by cGMP and cGMP-dependent kinase I in renal fibrosis

Agents that enhance production of nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) ameliorate the progression of renal fibrosis. However, the molecular mechanism of this process is not fully understood. We hypothesize that the antifibrotic effects of cGMP and cGMP‐dependent kinase I (cGKI) are mediated via regulation of the TGFβ signalling pathway, both via ERK and the Smad‐dependent route. Kidney fibrosis was induced by unilateral ureter obstruction (UUO) in wild‐type and cGKI‐deficient (cGKI‐KO) mice. The cGMP/cGKI signalling pathway was activated by application of the soluble guanylate cyclase (sGC) stimulator BAY 41‐8543 (BAY), beginning 1 day after UUO. After 7 days, the antifibrotic effects of BAY were analysed by measuring mRNA and protein expression of characteristic fibrotic biomarkers. The effects of cGMP/TGFβ on cultured fibroblasts were also analysed in vitro. BAY application influenced the activity of the extracellular matrix (ECM)‐degrading matrix metalloproteases (MMP2 and MMP9) and their inhibitor tissue inhibitors of metalloproteinase‐1, the secretion of cytokines (e.g. IL‐6) and the expression pattern of ECM proteins (e.g. collagen, fibronectin) and profibrotic mediators (e.g. connective tissue growth factors and plasminogen‐activator inhibitor‐1). Activation of the cGMP/cGKI signalling pathway showed protective effects against fibrosis which were mediated by inhibition of P‐Erk1/2 and translocation of P‐smad3. The elucidation of these signalling mechanisms might support the development of new therapeutic options regarding cGMP/cGKI‐mediated antifibrotic actions.

Cardioprotective Effect of Ulmus wallichiana Planchon in β-Adrenergic Agonist Induced Cardiac Hypertrophy

Ulmus wallichiana Planchon (Family: Ulmaceae), a traditional medicinal plant, was used in fracture healing in the folk tradition of Uttarakhand, Himalaya, India. The present study investigated the cardioprotective effect of ethanolic extract (EE) and butanolic fraction (BF) of U. wallichiana in isoprenaline (ISO) induced cardiac hypertrophy in Wistar rats. Cardiac hypertrophy was induced by ISO (5 mg/kg/day, subcutaneously) in rats. Treatment was performed by oral administration of EE and BF of U. wallichiana (500 and 50 mg/kg/day). The blood pressure (BP) and heart rate (HR) were measured by non-invasive blood pressure measurement technique. Plasma renin, Ang II, NO, and cGMP level were estimated using an ELISA kit. Angiotensin converting enzyme activity was estimated. BP and HR were significantly increased in ISO group (130.33 ± 1.67 mmHg vs. 111.78 ± 1.62 mmHg, p < 0.001 and 450.51 ± 4.90 beats/min vs. 347.82 ± 6.91 beats/min, respectively, p < 0.001). The BP and HR were significantly reduced (EE: 117.53 ± 2.27 mmHg vs. 130.33 ± 1.67 mmHg, p < 0.001, BF: 119.74 ± 3.32 mmHg vs. 130.33 ± 1.67 mmHg, p < 0.001); HR: (EE: 390.22 ± 8.24 beats/min vs. 450.51 ± 4.90 beats/min, p < 0.001, BF: 345.38 ± 6.79 beats/min vs. 450.51 ± 4.90 beats/min, p < 0.001) after the treatment of EE and BF of U. wallichiana, respectively. Plasma renin, Ang II, ACE activity was decreased and NO, cGMP level were increased. The EE and BF of U. wallichiana down regulated the expression of ANP, BNP, TNF-α, IL-6, MMP9, β1-AR, TGFβ1 and up regulated NOS3, ACE2 and Mas expression level, respectively. Thus, this study demonstrated that U. wallichiana has cardioprotective effect against ISO induced cardiac hypertrophy.

Involvement of Cyclic Guanosine Monophosphate-Dependent Protein Kinase I in Renal Antifibrotic Effects of Serelaxin

Introduction: Kidney fibrosis has shown to be ameliorated through the involvement of cyclic guanosine monophosphate (cGMP) and its dependent protein kinase I (cGKI). Serelaxin, the recombinant form of human relaxin-II, increases cGMP levels and has shown beneficial effects on kidney function in acute heart failure patients. Antifibrotic properties of serelaxin are supposed to be mediated via relaxin family peptide receptor 1 and subsequently enhanced nitric oxide/cGMP to inhibit transforming growth factor-β (TGF-β) signaling. This study examines the involvement of cGKI in the antifibrotic signaling of serelaxin.

Methods and Results: Kidney fibrosis was induced by unilateral ureteral obstruction in wildtype (WT) and cGKI knock-out (KO) mice. After 7 days, renal antifibrotic effects of serelaxin were assessed. Serelaxin treatment for 7 days significantly increased cGMP in the kidney of WT and cGKI-KO. In WT, renal fibrosis was reduced through decreased accumulation of collagen1A1, total collagen, and fibronectin. The profibrotic connective tissue growth factor as well as myofibroblast differentiation were reduced and matrix metalloproteinases-2 and -9 were positively modulated after treatment. Moreover, Smad2 as well as extracellular signal-regulated kinase 1 (ERK1) phosphorylation were decreased, whereas phosphodiesterase (PDE) 5a phosphorylation was increased. However, these effects were not observed in cGKI-KO.

Conclusion: Antifibrotic renal effects of serelaxin are mediated via cGMP/cGKI to inhibit Smad2- and ERK1-dependent TGF-β signaling and increased PDE5a phosphorylation.

Activation of endothelial NO synthase by a xanthine derivative ameliorates hypoxia-induced apoptosis in endothelial progenitor cells

OBJECTIVES

Endothelial damage is strongly associated with cardiovascular diseases such as atherosclerosis, thrombosis and hypertension. Endothelial progenitor cells (EPCs) are primitive bone marrow (BM) cells that possess the capacity to mature into endothelial cells and play a role in neovascularization and vascular remodelling. This study aimed to investigate whether KMUP-1, a synthetic xanthine-based derivative, atorvastatin and simvastatin, can prevent endothelial dysfunction and apoptosis induced by hypoxia and to elucidate the underlying mechanisms.

METHODS

Mononuclear cells were separated and were induced to differentiate into EPCs. KMUP-1, atorvastatin or simvastatin were administered prior to hypoxia.

KEY FINDINGS

We found that EPCs exposed to hypoxia increased apoptosis as well as diminished proliferation. Pretreatment with KMUP-1, atorvastatin and simvastatin significantly prevented hypoxia-induced EPCs death and apoptosis, with associated increased of the Bcl-2/Bax ratio, and reduced caspase-3 and caspase-9 expression. We also assessed the nitrite production and Ser(1177)-phospho-eNOS expression and found that KMUP-1, atorvastatin and simvastatin not only increased the secretion of NO compared with the hypoxia group but also upregulated the eNOS activation.

CONCLUSIONS

KMUP-1 inhibited hypoxia-induced dysfunction and apoptosis in EPCs, which may be mediated through suppressing oxidative stress, upregulating eNOS and downregulating the caspase-3 signalling pathway.

Phosphodiesterase inhibitor KMUP-3 displays cardioprotection via protein kinase G and increases cardiac output via G-protein-coupled receptor agonist activity and Ca(2+) sensitization

KMUP-3 (7-{2-[4-(4-nitrobenzene) piperazinyl]ethyl}-1, 3-dimethylxanthine) displays cardioprotection and increases cardiac output, and is suggested to increase cardiac performance and improve myocardial infarction. To determine whether KMUP-3 improves outcomes in hypoperfused myocardium by inducing Ca(2+) sensitization to oppose protein kinase (PK)G-mediated Ca(2+) blockade, we measured left ventricular systolic blood pressure, maximal rates of pressure development, mean arterial pressure and heart rate in rats, and measured contractility and expression of PKs/RhoA/Rho kinase (ROCK)II in beating guinea pig left atria. Hemodynamic changes induced by KMUP-3 (0.5-3.0 mg/kg, intravenously) were inhibited by Y27632 [(R)-(+)-trans-4-1-aminoethyl)-N-(4-Pyridyl) cyclohexane carboxamide] and ketanserin (1 mg/kg, intravenously). In electrically stimulated left guinea pig atria, positive inotropy induced by KMUP-3 (0.1-100μM) was inhibited by the endothelial NO synthase (eNOS) inhibitors N-nitro-l-arginine methyl ester (L-NAME) and 7-nitroindazole, cyclic AMP antagonist SQ22536 [9-(terahydro-2-furanyl)-9H-purin-6-amine], soluble guanylyl cyclase (sGC) antagonist ODQ (1H-[1,2,4] oxadiazolo[4,3-a] quinoxalin-1-one), RhoA inhibitor C3 exoenzyme, β-blocker propranolol, 5-hydroxytryptamine 2A antagonist ketanserin, ROCK inhibitor Y27632 and KMUP-1 (7-{2-[4-(2-chlorobenzene) piperazinyl]ethyl}-1, 3-dimethylxanthine) at 10μM. Western blotting assays indicated that KMUP-3 (0.1-10μM) increased PKA, RhoA/ROCKII, and PKC translocation and CIP-17 (an endogenous 17-kDa inhibitory protein) activation. In spontaneous right atria, KMUP-3 induced negative chronotropy that was blunted by 7-nitroindazole and atropine. In neonatal myocytes, L-NAME inhibited KMUP-3-induced eNOS phosphorylation and RhoA/ROCK activation. In H9c2 cells, Y-27632 (50μM) and PKG antagonist KT5823 [2,3,9,10,11,12-hexahydro-10R- methoxy-2,9-dimethyl-1-oxo-9S,12R-epoxy-1H-diindolo(1,2,3-fg:3',2',1'-kl) pyrrolo(3,4-i)(1,6)benzodiazocine-10-carboxylic acid, methyl ester] (3μM) reversed KMUP-3 (1-100μM)-induced Ca(2+)-entry blockade. GPCR agonist activity of KMUP-3 appeared opposed to KMUP-1, and increased cardiac output via Ca(2+) sensitization, and displayed cardioprotection via cyclic GMP/PKG-mediated myocardial preconditioning in animal studies.

Xanthine-based KMUP-1 improves HDL via PPARγ/SR-B1, LDL via LDLRs, and HSL via PKA/PKG for hepatic fat loss

The phosphodiesterase inhibitor (PDEI)/eNOS enhancer KMUP-1, targeting G-protein coupled receptors (GPCRs), improves dyslipidemia. We compared its lipid-lowering effects with simvastatin and explored hormone-sensitive lipase (HSL) translocation in hepatic fat loss. KMUP-1 HCl (1, 2.5, and 5 mg/kg/day) and simvastatin (5 mg/kg/day) were administered in C57BL/6J male mice fed a high-fat diet (HFD) by gavage for 8 weeks. KMUP-1 inhibited HFD-induced plasma/liver TG, total cholesterol, and LDL; increased HDL/3-hydroxy-3-methylglutaryl-CoA reductase (HMGR)/Rho kinase II (ROCK II)/PPARγ/ABCA1; and decreased liver and body weight. KMUP-1 HCl in drinking water (2.5 mg/200 ml tap water) for 1–14 or 8–14 weeks decreased HFD-induced liver and body weight and scavenger receptor class B type I expression and increased protein kinase A (PKA)/PKG/LDLRs/HSL expression and immunoreactivity. In HepG2 cells incubated with serum or exogenous mevalonate, KMUP-1 (10⁻⁷∼10⁻⁵ M) reversed HMGR expression by feedback regulation, colocalized expression of ABCA1/apolipoprotein A-I/LXRα/PPARγ, and reduced exogenous geranylgeranyl pyrophosphate/farnesyl pyrophosphate (FPP)-induced RhoA/ROCK II expression. A guanosine 3′,5′-cyclic monophosphate (cGMP) antagonist reversed KMUP-1-induced ROCK II reduction, indicating cGMP/eNOS involvement. KMUP-1 inceased PKG and LDLRs surrounded by LDL and restored oxidized LDL-induced PKA expresion. Unlike simvastatin, KMUP-1 could not inhibit ¹⁴C mevalonate formation. KMUP-1 could, but simvastatin could not, decrease ROCK II expression by exogenous FPP/CGPP. KMUP-1 improves HDL via PPARγ/LXRα/ABCA1/Apo-I expression and increases LDLRs/PKA/PKG/HSL expression and immunoreactivity, leading to TG hydrolysis to lower hepatic fat and body weight.

KMUP-1 Promotes Osteoblast Differentiation Through cAMP and cGMP Pathways and Signaling of BMP-2/Smad1/5/8 and Wnt/β-Catenin

Phosphodiesterase (PDE) inhibitors have been suggested as a possible candidate for the treatment of osteopenia, including osteoporosis. KMUP-1 is a novel xanthine derivative with inhibitory activities on the PDE 3, 4, and 5 iso-enzymes to suppress the degradation of cAMP and cGMP. This study aimed to investigate the effect of KMUP-1 on osteoblast differentiation and the underlying cellular and molecular mechanisms. Primary osteoblasts and osteoblastic MC3T3-E1 cells were examined. KMUP-1 enhanced alkaline phosphatase (ALP) activity and mineralization compared to untreated controls in primary osteoblasts and MC3T3-E1 cells. KMUP-1 also increased the mRNA expression of the osteoblastic differentiation markers, including collagen type 1a, ALP, osteocalcin, osteoprotegerin, BMP-2, and Runx2, a key transcription regulator for osteoblastic differentiation. The osteogenic effect of KMUP-1 was abolished by BMP signaling inhibitor, noggin. Furthermore, we found that KMUP-1 upregulated Smad1/5/8 phosphorylations with subsequent BRE-Luc activation confirmed by transient transfection assay. In addition, KMUP-1 inactivated glycogen synthase kinase-3β (GSK-3β), with associated nuclear translocation of β-catenin. Co-treatment with H89 and KT5823, cAMP and cGMP pathway inhibitors, respectively, reversed the KMUP-1-induced activations of Smad1/5/8, β-catenin, and Runx2. The findings demonstrate for the first time that KMUP-1 can promote osteoblast maturation and differentiation in vitro via BMP-2/Smad1/5/8 and Wnt/β-catenin pathways. These effects are mediated, in part, by the cAMP and cGMP signaling. Thus, KMUP-1 may be a novel osteoblast activator and a potential new therapy for osteoporosis.

KMUP-1 Attenuates Endothelin-1-Induced Cardiomyocyte Hypertrophy through Activation of Heme Oxygenase-1 and Suppression of the Akt/GSK-3β, Calcineurin/NFATc4 and RhoA/ROCK Pathways

The signaling cascades of the mitogen activated protein kinase (MAPK) family, calcineurin/NFATc4, and PI3K/Akt/GSK3, are believed to participate in endothelin-1 (ET-1)-induced cardiac hypertrophy. The aim of this study was to investigate whether KMUP-1, a synthetic xanthine-based derivative, prevents cardiomyocyte hypertrophy induced by ET-1 and to elucidate the underlying mechanisms. We found that in H9c2 cardiomyocytes, stimulation with ET-1 (100 nM) for 4 days induced cell hypertrophy and enhanced expressions of hypertrophic markers, including atrial natriuretic peptide and brain natriuretic peptide, which were all inhibited by KMUP-1 in a dose-dependent manner. In addition, KMUP-1 prevented ET-1-induced intracellular reactive oxygen species generation determined by the DCFH-DA assay in cardiomyocytes. KMUP-1 also attenuated phosphorylation of ERK1/2 and Akt/GSK-3β, and activation of calcineurin/NFATc4 and RhoA/ROCK pathways induced by ET-1. Furthermore, we found that the expression of heme oxygenase-1 (HO-1), a stress-response enzyme implicated in cardio-protection, was up-regulated by KMUP-1. Finally, KMUP-1 attenuated ET-1-stimulated activator protein-1 DNA binding activity. In conclusion, KMUP-1 attenuates cardiomyocyte hypertrophy induced by ET-1 through inhibiting ERK1/2, calcineurin/NFATc4 and RhoA/ROCK pathways, with associated cardioprotective effects via HO-1 activation. Therefore, KMUP-1 may have a role in pharmacological therapy of cardiac hypertrophy.

Baicalein Inhibits HMGB1 Release and MMP-2/-9 Expression in Lipopolysaccharide-Induced Cardiac Hypertrophy

Myocardial dysfunction, a common complication after sepsis, significantly contributes to the death of patients with septic shock. In the search for potentially effective drugs to decrease mortality from sepsis, we investigated the cardioprotective effects of baicalein, a flavonoid present in the root of Scutellaria baicalensis, on lipopolysaccharide (LPS)-induced pro-inflammatory cytokine production and matrix metalloproteinase-2 and -9 (MMP-2/-9) expression. We found that baicalein significantly attenuated LPS-induced cardiac hypertrophy and counteracted reactive oxygen species (ROS) generation in neonatal rat cardiomyocytes. In addition, pretreatment with baicalein inhibited LPS-induced early (e.g., tumor necrosis factor-α (TNF-α) and interleukin-6) and late (e.g., high mobility group box 1 (HMGB1) pro-inflammatory cytokine release, inducible nitric oxide synthase (iNOS) expression and NO production. Finally, baicalein also significantly down-regulated the expression of MMP-2/-9 and attenuated HMGB1 translocation from the nucleus to the cytoplasm. These results suggest that baicalein can protect cardiomyocytes from LPS-induced cardiac injury via the inhibition of ROS and inflammatory cytokine production. These cardioprotective effects are possibly mediated through the inhibition of the HMGB1 and MMP-2/-9 signaling pathways.

HIP-55/DBNL-dependent regulation of adrenergic receptor mediates the ERK1/2 proliferative pathway

The activation of β-adrenergic receptors (β-ARs) plays a key role in regulating cardiac function. However, the detailed regulatory mechanisms of β-AR-induced fibrosis are still unclear. We used a proteomics approach to analyze the changes in protein expression patterns in cardiac fibrosis with β-AR stimulation. HIP-55 (also called debrin-like; DBNL) was revealed as a novel regulator in the signaling regulatory network with β-AR activation. Further studies of both HIP-55-overexpressed and -deficient cardiac fibroblasts indicated that HIP-55 negatively regulated β-AR-activated cardiac fibroblast proliferation and the proliferative signaling pathway may be associated with the extracellular signal-regulated protein kinase (ERK) activation. Our data provide a new mechanistic insight into the role of HIP-55 in β-AR-induced cardiac fibroblast proliferation and suggest a new treatment strategy for proliferative disorders.

Xanthine derivative KMUP-1 reduces inflammation and hyperalgesia in a bilateral chronic constriction injury model by suppressing MAPK and NFκB activation

Neuropathic pain is characterized by spontaneous pain, hyperalgesia, and allodynia. The aim of this study was to investigate whether KMUP-1 (7-[2-[4-(2-chlorobenzene)piperazinyl]ethyl]-1,3-dimethylxanthine) could improve pain hypersensitivity and reduce inflammatory mediators, and also explore possible mechanisms in the rat sciatic nerve using bilateral chronic constriction injury (CCI) to induce neuropathic pain. Sprague-Dawley rats were randomly divided into four groups: Sham, Sham+KMUP-1, CCI, and CCI+KMUP-1. KMUP-1 (5 mg/kg/day) was injected intraperitoneally starting at day 1 after surgery. Mechanical and thermal responses were assessed before surgery and at days 3, 7, and 14 after CCI. Sciatic nerves around the injury site were isolated for Western blots and enzyme-linked immunosorbent assay to analyze protein and cytokine levels. The results show that thermal hyperalgesia and mechanical allodynia were reduced in the KMUP-1 treated group as compared to that in the CCI group. Inflammatory proteins (COX2, iNOS, and nNOS) and proinflammatory cytokines (TNF-α and IL-1β) induced by CCI were decreased in the KMUP-1 treated group at day 7 after surgery. KMUP-1 also inhibited neuropathic pain-related mechanisms, including p38 and ERK activation, but not JNK. Furthermore, KMUP-1 blocked IκB phosphorylation (p-IκB) and phospho-nuclear factor κB (p-NF-κB) translocation to nuclei. Double immunofluorescent staining further demonstrated that p-IκB (an indicator of activated NFκB) and p-NFκB proteins were almost abolished by KMUP-1 in peripheral macrophages and spinal microglia cells at day 7 after surgery. On the basis of these findings, we concluded that KMUP-1 has antiinflammatory and antihyperalgesia properties in CCI-induced neuropathic pain via decreases in MAPKs and NF-κB activation.

Kmup-1 Protects Kidney from Streptozotocin-Induced Pro-Inflammation in Early Diabetic Nephropathy by Restoring Enos/Pparγ and Inhibiting MMP-9

KMUP-1 increases nitric oxide (NO) via endothelium nitric-oxide synthase (eNOS). Deficiency of eNOS and peroxisome proliferator-activated receptor-γ (PPARγ) is the pathogenesis of diabetic nephropathy (DN). This study aims to investigate whether KMUP-1 inhibits streptozotocin (STZ)-induced proinflammation in early DN. In experiments, STZ was used to induce diabetes in Wistar rats. Twenty-four male rats were randomly divided into four groups, including control, STZ (65 mg/kg, i.p.), STZ+KMUP-1(1 mg/kg) and STZ+KMUP-1 (2.5 mg/kg). KMUP-1 HCl was dissolved in distilled water for oral administration. The morphology of renal tissues was evaluated by periodic acid-schiff (PAS) staining and immunohistochemistry of eNOS. The expressions of matrix metalloproteinase-2/-9 (MMP-2/-9), eNOS, B-cell lymphoma 2 (Bcl-2), Bcl-2– associated X protein (Bax) and PPARγ of renal tissues were examined by Western blotting technique. NO production was evaluated by Griess reagent. Oxidative stress was evaluated by measuring reactive oxygen species (ROS). Results indicated that STZ-induced diabetic mellitus (DM) and subsequent DN, including excessive deposition of extracellular matrix (ECM) accompanied by enhanced MMP-2/-9, raised ROS production, increased Bcl-2/Bax ratio and decreased eNOS/PPARy over a period of 4 weeks. KMUP-1 inhibited STZ-induced hyperglycemia, BUN, MMP-2/MMP-9, and restored eNOS-PPARγ expression in renal tissues. Immunohistochemistry (IHC) of eNOS in glomeruli of renal cortical tissue sections indicated that KMUP-1 restored the eNOS caused by STZ. PAS staining of glomeruli indicated that KMUP-1 could not significantly reduce STZ-induced ECM expansion. Moreover, KMUP-1 increased Bcl-2/Bax and decreased ROS. In summary, KMUP-1 inhibits STZ-induced proinflammation in early DN by restoring PPARγ/eNOS and inhibiting MMP-9.

A xanthine-derivative K(+)-channel opener protects against serotonin-induced cardiomyocyte hypertrophy via the modulation of protein kinases

This study investigated whether KMUP-1, a xanthine-derivative K⁺ channel opener, could prevent serotonin-induced hypertrophy in H9c2 cardiomyocytes via L-type Ca²⁺ channels (LTCCs). Rat heart-derived H9c2 cells were incubated with serotonin (10 μM) for 4 days. The cell size increased by 155.5%, and this was reversed by KMUP-1 (≥1 μM), and attenuated by the LTCC blocker verapamil (1 μM) and the 5-HT_2A antagonist ketanserin (0.1 μM), but unaffected by the 5-HT_2B antagonist SB206553. A perforated whole-cell patch-clamp technique was used to investigate Ca²⁺ currents through LTCCs in serotonin-induced H9c2 hypertrophy, in which cell capacitance and current density were increased. The LTCC current (I_Ca,L) increased ~2.9-fold in serotonin-elicited H9c2 hypertrophy, which was attenuated by verapamil and ketanserin, but not affected by SB206553 (0.1 μM). Serotonin-increased I_Ca,L was reduced by KMUP-1, PKA and PKC inhibitors (H-89, 1 μM and chelerythrine, 1 μM) while the current was enhanced by the PKC activator PMA, (1 μM) but not the PKA activator 8-Br-cAMP (100 μM), and was abolished by KMUP-1. In contrast, serotonin-increased I_Ca,L was blunted by the PKG activator 8-Br-cGMP (100 μM), but unaffected by the PKG inhibitor KT5823 (1 μM). Notably, KMUP-1 blocked serotonin-increased I_Ca,L but this was partially reversed by KT5823. In conclusion, serotonin-increased I_Ca,L could be due to activated 5-HT_2A receptor-mediated PKA and PKC cascades, and/or indirect interaction with PKG. KMUP-1 prevents serotonin-induced H9c2 cardiomyocyte hypertrophy, which can be attributed to its PKA and PKC inhibition, and/or PKG stimulation.

An animal model of stress-induced cardiomyopathy utilizing the social defeat paradigm

Stress-induced cardiomyopathy (SIC) is a form of acute heart disease triggered by extreme psychological stress. In patients who develop SIC, the outward symptoms are almost indistinguishable from acute myocardial infarction (AMI). However, some important criteria differentiate patients with SIC from those with AMI. Patients with SIC: (1) experience some form of extreme psychological stress from minutes to hours before developing heart disease, (2) do not suffer from atherosclerosis or coronary artery obstruction, and 3) exhibit abnormal ballooning of the left ventricle. In the present study, the resident-intruder (RI) social defeat test was investigated as a potential rat model for stressed-induced cardiomyopathy. Adult Long-Evans rats were implanted with a biotelemetry transmitter for ECG recordings and habituated for two weeks. An intruder rat was placed in the cage of a resident rat behind a wire-mesh partition for 5 min. The partition was then removed for 5 min to allow direct contact between the intruder and resident rats. After this interval, the wire-mesh partition was replaced and the intruder rat remained behind the partition for an additional 50 min. Behavioral responses were noted and ECG recordings were collected during the entire 60-min testing period. Upon completion of the test, the intruder rat was removed from the cage of the resident rat and sacrificed. The heart was examined and blood was collected. Heart weight/body weight ratio, left ventricle/body weight ratio, heart length, plasma corticosterone levels, and plasma troponin I levels of intruder rats were significantly higher as compared to control rats. Intruder rats significantly increased their heart rate during the first 5 min of the RI test. It is concluded that the RI test to induce social defeat is a novel rodent paradigm for modeling stress-induced cardiomyopathy in the human.

KMUP-1 suppresses RANKL-induced osteoclastogenesis and prevents ovariectomy-induced bone loss: roles of MAPKs, Akt, NF-κB and calcium/calcineurin/NFATc1 pathways

Background

KMUP-1 is a xanthine derivative with inhibitory activities on the phosphodiesterase (PDE) 3,4 and 5 isoenzymes to suppress the degradation of cyclic AMP and cyclic GMP. However, the effects of KMUP-1 on osteoclast differentiation are still unclear. In this study, we investigated whether KMUP-1 inhibits osteoclastogenesis induced by RANKL in RAW 264.7 cells and bone loss induced by ovariectomy in mice, and the underlying mechanisms.

Principal Findings

In vitro, KMUP-1 inhibited RANKL-induced TRAP activity, the formation of multinucleated osteoclasts and resorption-pit formation. It also inhibited key mediators of osteoclastogenesis including IL-1β, IL-6, TNF-α and HMGB1. In addition, KMUP-1 inhibited RANKL-induced activation of signaling molecules (Akt, MAPKs, calcium and NF-κB), mRNA expression of osteoclastogensis-associated genes (TRAP, MMP-9, Fra-1, and cathepsin K) and transcription factors (c-Fos and NFATc1). Furthermore, most inhibitory effects of KMUP-1 on RANKL-mediated signal activations were reversed by a protein kinase A inhibitor (H89) and a protein kinase G inhibitor (KT5823). In vivo, KMUP-1 prevented loss of bone mineral content, preserved serum alkaline phosphate and reduced serum osteocalcin in ovariectomized mice.

Conclusions

KMUP-1 inhibits RANKL-induced osteoclastogenesis in vitro and protects against ovariectomy-induced bone loss in vivo. These effects are mediated, at least in part, by cAMP and cGMP pathways. Therefore, KMUP-1 may have a role in pharmacologic therapy of osteoporosis.

Assisted peripheral nerve recovery by KMUP-1, an activator of large-conductance Ca(2+)-activated potassium channel, in a rat model of sciatic nerve crush injury

BACKGROUND

Axonal regeneration in peripheral nerves after injury is a complicated process. Numerous cytokines, growth factors, channels, kinases, and receptors are involved, and matrix metalloproteinase-9 (MMP-9) has been implicated in the pathogenesis subsequent to nerve injury. In this study, the effect of KMUP-1, an activator of large-conductance Ca(2+)-activated potassium channel, on functional recovery, myelinated axon growth, and immunoreactivity of MMP-9 was evaluated in rats subjected to sciatic nerve crush injury.

METHOD

A total of 144 male Sprague-Dawley rats were divided into the following six groups (n = 24/group): group 1, sham-operated; group 2, sciatic nerve injury without treatment; group 3, injured and vehicle-treated; group 4, injured and treated with 1 mM KMUP-1 by topical application; group 5, injured and treated with 10 mM KMUP-1; group 6, injured and treated with 50 mM KMUP-1. Functional recovery was evaluated using walking track analysis at 1, 2, 3, and 4 weeks (n = 6/group at each time point) after injury. In addition, the number of myelinated axons and MMP-9 in the nerve was also examined.

FINDINGS

Animals subjected to sciatic nerve crush injury had decreased motor function, a reduced number of myelinated axons, and increased MMP-9 in the nerve. Treatment with KMUP-1 concentration-dependently improved functional recovery, increased the number of myelinated axons, and decreased MMP-9.

CONCLUSIONS

These results suggest that KMUP-1 may be a novel agent for assisting peripheral nerve recovery after injury. The beneficial effect is probably due to known ability of the compound in activating the nitric oxide/cGMP/protein kinase G pathway.

Treatment of chronic heart failure with β-adrenergic receptor antagonists: a convergence of receptor pharmacology and clinical cardiology

Despite the absence of a systematic development plan, β-blockers have reached the top tier of medical therapies for chronic heart failure. The successful outcome was due to the many dedicated investigators who produced, over a 30-year period, increasing evidence that β-blocking agents should or actually did improve the natural history of dilated cardiomyopathies and heart failure. It took 20 years for supportive evidence to become undeniable, at which time in 1993 the formidable drug development resources of large pharmaceutical companies were deployed into Phase 3 trials. Success then came relatively quickly, and within 8 years multiple agents were on the market in the United States and Europe. Importantly, there is ample room to improve antiadrenergic therapy, through novel approaches exploiting the nuances of receptor biology and/or intracellular signaling, as well as through pharmacogenetic targeting.

Tanshinone IIA protects against cardiac hypertrophy via inhibiting calcineurin/NFATc3 pathway

Pathological cardiac hypertrophy induced by adrenergic overactivation can subsequently develop to heart failure which remains as a leading cause of mortality worldwide. Tanshinone IIA is a lipid-soluble pharmacologically active compound extracted from the rhizome of the Chinese herb Salvia miltiorrhiza, a well-known traditional Chinese medicine used for the treatment of cardiovascular disorders. However, little is know about the effect of Tanshinone IIA on cardiac hypertrophy. The present study was aimed to investigate whether Tanshinone IIA prevents cardiac hypertrophy induced by isoproterenol (ISO) and to clarify its possible mechanisms. Cardiomyocytes hypertrophy was induced by ISO 10 μM for 48 h with or without Tanshinone IIA 10, 30, 100 μM pretreatment, and evaluated by determining the cell size and the expression of ANP, BNP, β-MHC, Calcineurin, and NFATc3 by real-time PCR and western blot. We found that Tanshinone IIA pretreatment attenuated the enlargement of cell surface area induced by ISO in cultured cardiomyocytes. The mRNA level of ANP, BNP and β-MHC was obviously elevated in ISO-treated cardiac cells, which was effectively inhibited by Tanshinone IIA. Moreover, we found that Tanshinone IIA pretreatment could prevent the augment of intracellular calcium transient in ISO-treated cardiomyocytes. The further study revealed that Calcineurin, NFATc3, ANP, BNP and β-MHC proteins were upregulated by ISO in ventricular myocytes, and Tanshinone IIA pretreatment significantly attenuate the increased expression of Calcineurin, NFATc3, ANP, BNP and β-MHC proteins. In summary, Tanshinone IIA attenuated cardiomyocyte hypertrophy induced by ISO through inhibiting Calcineurin/NFATc3 pathway, which provides new insights into the pharmacological role and therapeutic mechanism of Tanshinone IIA in heart diseases.

KMUP-3 attenuates ventricular remodelling after myocardial infarction through eNOS enhancement and restoration of MMP-9/TIMP-1 balance

BACKGROUND AND PURPOSE

Previously, 7-[2-[4-(4-nitrobenzene)piperazinyl]ethyl]-1, 3-dimethylxanthine (KMUP-3) has been shown to induce aortic smooth muscle relaxation through K(ATP) channel opening and endothelial nitric oxide synthase (eNOS) enhancement. We further investigated whether KMUP-3 protects against myocardial remodelling after myocardial infarction (MI), and whether KMUP-3 increases the expression of eNOS in MI rats.

EXPERIMENTAL APPROACH

Wistar rats were randomly allocated into three groups: MI (n= 10), MI + KMUP-3 group (n= 10) and sham group (n= 10). MI was induced by ligation of the left anterior descending coronary artery. After recovery, the MI + KMUP-3 group received KMUP-3 (0.3 mg·kg(-1) ·day(-1) ) infusion for 4 weeks, while the MI and sham group received vehicle only. To further confirm that the effect of KMUP-3 is dependent on eNOS, KMUP-3 was applied in the culture of transforming growth factor-β-stimulated human cardiac fibroblasts.

KEY RESULTS

KMUP-3 treatment attenuated cardiac hypertrophy post-MI and improved cardiac function. The fibrotic area was reduced by KMUP-3 both in central-, peri- and non-infarction areas. KMUP-3 enhanced the expression of eNOS and tissue inhibitor of metalloproteinase-1 (TIMP-1), but reduced matrix metalloproteinase-9 (MMP-9) expression. In vitro, the activities of KMUP-3 were blocked by pretreatment with the eNOS inhibitor N(ω) -nitro-L-arginine methyl ester.

CONCLUSIONS AND IMPLICATIONS

The K(ATP) channel opener KMUP-3 preserved cardiac function after MI by enhancing the expression of eNOS. In addition, KMUP-3 restored the myocardial MMP-9/TIMP-1 balance and attenuated ventricular remodelling by an eNOS-dependent mechanism.

Eugenolol and Glyceryl-Isoeugenol Suppress LPS-Induced INOS Expression by Down-Regulating NF-κB and AP-1 through Inhibition of Mapks and AKT/IκBα Signaling Pathways in Macrophages

Eugenol and isoeugenol, two components of clover oil, have been reported to possess several biomedical properties, such as anti-inflammatory, antimicrobial and antioxidant effects. This study aims to examine the anti-inflammatory effects of eugenol, isoeugenol and four of their derivatives on expression of inducible nitric oxide synthase (iNOS) activated by lipopolysaccharide (LPS) in mouse macrophages (RAW 264.7), and to investigate molecular mechanisms underlying these effects. We found that two derivatives, eugenolol and glyceryl-isoeugenol, had potent inhibitory effects on LPS-induced upregulation of nitrite levels, iNOS protein and iNOS mRNA. In addition, they both suppressed the release of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) induced by LPS. Moreover, they both attenuated the DNA binding of NF-κB and AP-1, phosphorylation of inhibitory κBα (IκBα), and nuclear translocation of p65 protein induced by LPS. Finally, we demonstrated that glyceryl-isoeugenol suppressed the phosphorylation of ERK1/2, JNK and p38 MAPK, whereas eugenolol suppressed the phosphorylation of ERK1/2 and p38 MAPK. Taken together, these results suggest that that eugenolol and glyceryl-isoeugenol suppress LPS-induced iNOS expression by down-regulating NF-κB and AP-1 through inhibition of MAPKs and Akt/IκBα signaling pathways. Thus, this study implies that eugenolol and glyceryl-isoeugenol may provide therapeutic benefits for inflammatory diseases.

The xanthine derivative KMUP-1 inhibits models of pulmonary artery hypertension via increased NO and cGMP-dependent inhibition of RhoA/Rho kinase

BACKGROUND AND PURPOSE

KMUP-1 is known to increase cGMP, enhance endothelial nitric oxide synthase (eNOS) and suppress Rho kinase (ROCK) expression in smooth muscle. Here, we investigated the mechanism of action of KMUP-1 on acute and chronic pulmonary artery hypertension (PAH) in rats.

EXPERIMENTAL APPROACH

We measured pulmonary vascular contractility, wall thickening, eNOS immunostaining, expressions of ROCK II, RhoA activation, myosin phosphatase target subunit 1 (MYPT1) phosphorylation, eNOS, soluble guanylyl cyclase (sGC), protein kinase G (PKG) and phosphodiesterase 5A (PDE-5A), blood oxygenation and cGMP/cAMP, and right ventricular hypertrophy (RVH) in rats.

KEY RESULTS

In rings of intact pulmonary artery (PA), KMUP-1 relaxed the vasoconstriction induced by phenylephrine (10 microM) or the thromboxane A(2)-mimetic U46619 (0.5 microM). In endothelium-denuded PA rings, this relaxation was reduced. In acute PAH induced by U46619 (2.5 microg x kg(-1) x min(-1), 30 min), KMUP-1 relaxed vasoconstriction by enhancing levels of eNOS, sGC and PKG, suppressing those of PDE-5A, RhoA/ROCK II activation and MYPT1 phosphorylation, and restoring oxygenation in blood and cGMP/cAMP in plasma. Incubating smooth muscle cells from PA (PASMCs) with KMUP-1 inhibited thapsigargin-induced Ca(2+) efflux and angiotensin II-induced Ca(2+) influx. In chronic PAH model induced by monocrotaline, KMUP-1 increased eNOS and reduced RhoA/ROCK II activation/expression, PA wall thickening, eNOS immunostaining and RVH. KMUP-1 and sildenafil did not inhibit monocrotaline-induced PDE-5A expression.

CONCLUSION AND IMPLICATIONS

KMUP-1 decreased PAH by enhancing NO synthesis by eNOS, with consequent cGMP-dependent inhibition of RhoA/ROCK II and Ca(2+) desensitization in PASMCs. KMUP-1 has the potential to reduce vascular resistance, remodelling and RVH in PAH.