p38 Mitogen-Activated Protein Kinase Inhibition Ameliorates Angiotensin II–Induced Target Organ Damage

Heart failure with preserved ejection fraction: The role of inflammation

Heart failure (HF) is a debilitating clinical syndrome affecting 64.3 million patients worldwide. More than 50% of HF cases are attributed to HF with preserved ejection fraction (HFpEF), an entity growing in prevalence and mortality. Although recent breakthroughs reveal the prognostic benefits of sodium-glucose co-transporter 2 inhibitors (SGLT2i) in HFpEF, there is still a lack of effective pharmacological therapy available. This highlights a major gap in medical knowledge that must be addressed. Current evidence attributes HFpEF pathogenesis to an interplay between cardiometabolic comorbidities, inflammation, and renin-angiotensin-aldosterone-system (RAAS) activation, leading to cardiac remodelling and diastolic dysfunction. However, conventional RAAS blockade has demonstrated limited benefits in HFpEF, which emphasises that alternative therapeutic targets should be explored. Presently, there is limited literature examining the use of anti-inflammatory HFpEF therapies despite growing evidence supporting its importance in disease progression. Hence, this review aims to explore current perspectives on HFpEF pathogenesis, including the importance of inflammation-driven cardiac remodelling and the therapeutic potential of anti-inflammatory therapies.

SARS-CoV-2 spike protein-ACE2 interaction increases carbohydrate sulfotransferases and reduces N-acetylgalactosamine-4-sulfatase by p38 MAPK

Immunostaining in lungs of patients who died with COVID-19 infection showed increased intensity and distribution of chondroitin sulfate and decline in N-acetylgalactostamine-4-sulfatase (Arylsulfatase B; ARSB). To explain these findings, human small airway epithelial cells were exposed to the SARS-CoV-2 spike protein receptor binding domain (SPRBD) and transcriptional mechanisms were investigated. Phospho-p38 MAPK and phospho-SMAD3 increased following exposure to the SPRBD, and their inhibition suppressed the promoter activation of the carbohydrate sulfotransferases CHST15 and CHST11, which contributed to chondroitin sulfate biosynthesis. Decline in ARSB was mediated by phospho-38 MAPK-induced N-terminal Rb phosphorylation and an associated increase in Rb-E2F1 binding and decline in E2F1 binding to the ARSB promoter. The increases in chondroitin sulfotransferases were inhibited when treated with phospho-p38-MAPK inhibitors, SMAD3 (SIS3) inhibitors, as well as antihistamine desloratadine and antibiotic monensin. In the mouse model of carrageenan-induced systemic inflammation, increases in phospho-p38 MAPK and expression of CHST15 and CHST11 and declines in DNA-E2F binding and ARSB expression occurred in the lung, similar to the observed effects in this SPRBD model of COVID-19 infection. Since accumulation of chondroitin sulfates is associated with fibrotic lung conditions and diffuse alveolar damage, increased attention to p38-MAPK inhibition may be beneficial in ameliorating Covid-19 infections.

Inhibiting the MAPK pathway improves heart failure with preserved ejection fraction induced by salt-sensitive hypertension

Heart failure (HF) preserved ejection fraction (HFpEF) accounts for almost 50% of HF, and hypertension is one of the pathogenies. The MAPK signaling pathway is closely linked to heart failure and hypertension; however, its function in HEpEF resulting from salt-sensitive hypertension is not well understood. In this work, a salt-sensitive hypertension-induced HEpEF model was established based on deoxycorticosterone acetate-salt (DOCA-salt) hypertension mice. The impact of the MAPK inhibitor (Doramapimod) on HEpEF induced by salt-sensitive hypertension was assessed through various measures, such as blood pressure, transthoracic echocardiography, running distance, and histological analysis, to determine its therapeutic effectiveness on cardiac function. In addition, the effects of high salt on myogenic cells were also evaluated in vitro using qRTPCR. The LV ejection fractions (LVEF) in DOCA-salt hypertension mice were over 50%, indicating that the salt-sensitive hypertension-induced HFpEF model was successful. RNA-seq revealed that the MAPK signaling pathway was upregulated in the HFpEF model compared with the normal mice, accompanied by hypertension, impaired running distance, restricted cardiac function, increased cross-sectional and fibrosis area, and upregulation of heart failure biomarkers, including GAL-3, LDHA and BNP. The application of Doramapimod could improve blood pressure, cardiomyocyte hypertrophy, and myocardial fibrosis, as well as decrease the aforementioned heart failure biomarkers. The qRTPCR results showed similar findings to these observations. Our findings suggest that the use of a MAPK inhibitor (Doramapimod) could be a potential treatment for salt-sensitive hypertension-induced HFpEF.

Inflammatory pathways in COVID-19: Mechanism and therapeutic interventions

The 2019 coronavirus disease (COVID-19) pandemic has become a global crisis. In the immunopathogenesis of COVID-19, SARS-CoV-2 infection induces an excessive inflammatory response in patients, causing an inflammatory cytokine storm in severe cases. Cytokine storm leads to acute respiratory distress syndrome, pulmonary and other multiorgan failure, which is an important cause of COVID-19 progression and even death. Among them, activation of inflammatory pathways is a major factor in generating cytokine storms and causing dysregulated immune responses, which is closely related to the severity of viral infection. Therefore, elucidation of the inflammatory signaling pathway of SARS-CoV-2 is important in providing otential therapeutic targets and treatment strategies against COVID-19. Here, we discuss the major inflammatory pathways in the pathogenesis of COVID-19, including induction, function, and downstream signaling, as well as existing and potential interventions targeting these cytokines or related signaling pathways. We believe that a comprehensive understanding of the regulatory pathways of COVID-19 immune dysregulation and inflammation will help develop better clinical therapy strategies to effectively control inflammatory diseases, such as COVID-19.

Synergistic Antiviral Activity of Pamapimod and Pioglitazone against SARS-CoV-2 and Its Variants of Concern

The SARS-CoV-2 pandemic remains a major public health threat, especially due to newly emerging SARS-CoV-2 Variants of Concern (VoCs), which are more efficiently transmitted, more virulent, and more able to escape naturally acquired and vaccine-induced immunity. Recently, the protease inhibitor Paxlovid® and the polymerase inhibitor molnupiravir, both targeting mutant-prone viral components, were approved for high-risk COVID-19 patients. Nevertheless, effective therapeutics to treat COVID-19 are urgently needed, especially small molecules acting independently of VoCs and targeting genetically stable cellular pathways which are crucial for viral replication. Pamapimod is a selective inhibitor of p38 Mitogen-Activated Protein Kinase alpha (p38 MAPKα) that has been extensively clinically evaluated for the treatment of rheumatoid arthritis. Signaling via p38 has recently been described as a key pathway for the replication of SARS-CoV-2. Here, we reveal that the combination of pamapimod with pioglitazone, an anti-inflammatory and approved drug for the treatment of type 2 diabetes, possesses potent and synergistic activity to inhibit SARS-CoV-2 replication in vitro. Both drugs showed similar antiviral potency across several cultured cell types and similar antiviral activity against SARS-CoV-2 Wuhan type, and the VoCs Alpha, Beta, Gamma, Delta, and Omicron. These data support the combination of pamapimod and pioglitazone as a potential therapy to reduce duration and severity of disease in COVID-19 patients, an assumption currently evaluated in an ongoing phase II clinical study.

Papaverine, a promising therapeutic agent for the treatment of COVID-19 patients with underlying cardiovascular diseases (CVDs)

The causative agent of coronavirus disease‐2019 (COVID‐19), severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), enters the host cells via an angiotensin‐converting enzyme 2 (ACE2)‐mediated endocytosis‐dependent manner. Because ACE2 is highly expressed in the heart, SARS‐CoV‐2 can severely infect heart tissue and arteries, causing acute and chronic damage to the cardiovascular system. Therefore, special attention should be paid to finding appropriate agents to protect this vital system during COVID‐19 treatment. Papaverine is a unique vasodilator alkaloid that is clinically used in the treatment of vasospasm. Interestingly, this compound has potent and direct effects on a wide range of viruses, and could also prevent viral exploitation mechanisms of the host cell facilities by inhibiting some cellular signaling pathways such as p38 MAPK. This pathway was recently introduced as a promising target for the treatment of COVID‐19. Papaverine also has anti‐inflammatory effects which is useful in combating the hyper‐inflammatory phase of the COVID‐19. Unlike some medications that have severe dosage‐restrictions in the treatment of COVID‐19 due to cardiac side effects, papaverine is recommended for use in many heart disorders. The ability of papaverine to treat COVID‐19 has become more promising when the results of some extensive screenings showed the strong ability of this compound to inhibit the cytopathic effects of SARS‐CoV‐2 with EC₅₀ of 1.1 μM. Having several therapeutic effects along with desired safety profile raises this hypothesis that papaverine could be a promising compound for the suppression of SARS‐CoV‐2 and prevention of ischemia/vasoconstriction‐related complications in COVID‐19 disease, especially in patients with underlying cardiovascular diseases (CVDs).

Can Epigenetics Help Solve the Puzzle Between Concomitant Cardiovascular Injury and Severity of Coronavirus Disease 2019?

ABSTRACT

The ongoing coronavirus disease 2019 (COVID-19) pandemic caused by SARS-CoV-2 has significant implications in patients with concomitant cardiovascular disease (CVD) because they are the population at the greatest risk of death. The treatment of such patients and complications may represent a new challenge for the fields of cardiology and pharmacology. Thus, understanding the involvement of this viral infection in CVD might help to reduce the aggressiveness of SARS-CoV-2 in causing multiorgan infection and damage. SARS-CoV-2 disturbs the host epigenome and several epigenetic processes involved in the pathophysiology of COVID-19 that can directly affect the function and structure of the cardiovascular system (CVS). Hence, it would be relevant to identify epigenetic alterations that directly impact CVS physiology after SARS-CoV-2 infection. This could contribute to the view of this virus-induced CVS injury and direct forthcoming tackles for COVID-19 treatment to reduce mortality in patients with CVD. Targeting epigenetic marks could offer strong evidence for the development of novel antiviral therapies, especially in the context of COVID-19-related CVS damage. In this review, we address some of the main signaling pathways that are currently known as being involved in COVID-19 pathophysiology and the importance of this glint on epigenetics and some of its modifiers (epidrugs) to control the unregulated epitope activity in the context of SARS-CoV-2 infection, COVID-19, and underlying CVD.

Kinases as Potential Therapeutic Targets for Anti-coronaviral Therapy

The global coronavirus disease-19 (COVID-19) has affected more than 140 million and killed more than 3 million people worldwide as of April 20, 2021. The novel human severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has been identified as an etiological agent for COVID-19. Several kinases have been proposed as possible mediators of multiple viral infections, including life-threatening coronaviruses like SARS-CoV-1, Middle East syndrome coronavirus (MERS-CoV), and SARS-CoV-2. Viral infections hijack abundant cell signaling pathways, resulting in drastic phosphorylation rewiring in the host and viral proteins. Some kinases play a significant role throughout the viral infection cycle (entry, replication, assembly, and egress), and several of them are involved in the virus-induced hyperinflammatory response that leads to cytokine storm, acute respiratory distress syndrome (ARDS), organ injury, and death. Here, we highlight kinases that are associated with coronavirus infections and their inhibitors with antiviral and potentially anti-inflammatory, cytokine-suppressive, or antifibrotic activity.

The triumvirate of NF-κB, inflammation and cytokine storm in COVID-19

The coronavirus disease (COVID-19) has once again reminded us of the significance of host immune response and consequential havocs of the immune dysregulation. The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) inflicts severe complications to the infected host, including cough, dyspnoea, fever, septic shock, acute respiratory distress syndrome (ARDs), and multiple organ failure. These manifestations are the consequence of the dysregulated immune system, which gives rise to excessive and unattended production of pro-inflammatory mediators. Elevated circulatory cytokine and chemokine levels are accompanied by spontaneous haemorrhage, thrombocytopenia and systemic inflammation, which are the cardinal features of life-threatening cytokine storm syndrome in advanced COVID-19 diseases. Coronavirus hijacked NF-kappa B (NF-κB) is responsible for upregulating the expressions of inflammatory cytokine, chemokine, alarmins and inducible enzymes, which paves the pathway for cytokine storm. Given the scenario, the systemic approach of simultaneous inhibition of NF-κB offers an attractive therapeutic intervention. Targeted therapies with proteasome inhibitor (VL-01, bortezomib, carfilzomib and ixazomib), bruton tyrosine kinase inhibitor (acalabrutinib), nucleotide analogue (remdesivir), TNF-α monoclonal antibodies (infliximab and adalimumab), N-acetylcysteine and corticosteroids (dexamethasone), focusing the NF-κB inhibition have demonstrated effectiveness in terms of the significant decrease in morbidity and mortality in severe COVID-19 patients. Hence, this review highlights the activation, signal transduction and cross-talk of NF-κB with regard to cytokine storm in COVID-19. Moreover, the development of therapeutic strategies based on NF-κB inhibition are also discussed herein.

Therapeutic potential of chelerythrine as a multi-purpose adjuvant for the treatment of COVID-19

Multifunctional nature of phytochemicals and their chemical diversity has attracted attention to develop leads originated from nature to fight COVID-19. Pharmacological activities of chelerythrine and its congeners have been studied and reported in the literature. This compound simultaneously has two key therapeutic effects for the treatment of COVID-19, antiviral and anti-inflammatory activities. Chelerythrine can prevent hyper-inflammatory immune response through regulating critical signaling pathways involved in SARS-CoV-2 infection, such as alteration in Nrf2, NF-κB, and p38 MAPK activities. In addition, chelerythrine has a strong protein kinase C-α/-β inhibitory activity suitable for cerebral vasospasm prevention and eryptosis reduction, as well as beneficial effects in suppressing pulmonary inflammation and fibrosis. In terms of antiviral activity, chelerythrine can fight with SARS-CoV-2 through various mechanisms, such as direct-acting mechanism, viral RNA-intercalation, and regulation of host-based antiviral targets. Although chelerythrine is toxic in vitro, the in vivo toxicity is significantly reduced due to its structural conversion to alkanolamine. Its multifunctional action makes chelerythrine a prominent compound for the treatment of COVID-19. Considering precautions related to the toxicity at higher doses, it is expected that this compound is useful in combination with proper antivirals to reduce the severity of COVID-19 symptoms.

The Effect of COVID-19 on NF-κB and Neurological Manifestations of Disease

The coronavirus disease that presumably began in 2019 (COVID-19) is a highly infectious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and has resulted in a pandemic. Initially, COVID-19 was thought to only affect respiration. However, accumulating evidence shows a wide range of neurological symptoms are also associated with COVID-19, such as anosmia/ageusia, headaches, seizures, demyelination, mental confusion, delirium, and coma. Neurological symptoms in COVID-19 patients may arise due to a cytokine storm and a heighten state of inflammation. The nuclear factor kappa-light-chain enhancer of activated B cells (NF-κB) is a central pathway involved with inflammation and is shown to be elevated in a dose-dependent matter in response to coronaviruses. NF-κB has a role in cytokine storm syndrome, which is associated with greater severity in COVID-19-related symptoms. Therefore, therapeutics that reduce the NF-κB pathway should be considered in the treatment of COVID-19. Neuro-COVID-19 units have been established across the world to examine the neurological symptoms associated with COVID-19. Neuro-COVID-19 is increasingly becoming an accepted term among scientists and clinicians, and interdisciplinary teams should be created to implement strategies for treating the wide range of neurological symptoms observed in COVID-19 patients.

Computational Identification of Potential Anti-Inflammatory Natural Compounds Targeting the p38 Mitogen-Activated Protein Kinase (MAPK): Implications for COVID-19-Induced Cytokine Storm

Severely ill coronavirus disease 2019 (COVID-19) patients show elevated concentrations of pro-inflammatory cytokines, a situation commonly known as a cytokine storm. The p38 MAPK receptor is considered a plausible therapeutic target because of its involvement in the platelet activation processes leading to inflammation. This study aimed to identify potential natural product-derived inhibitory molecules against the p38α MAPK receptor to mitigate the eliciting of pro-inflammatory cytokines using computational techniques. The 3D X-ray structure of the receptor with PDB ID 3ZS5 was energy minimized using GROMACS and used for molecular docking via AutoDock Vina. The molecular docking was validated with an acceptable area under the curve (AUC) of 0.704, which was computed from the receiver operating characteristic (ROC) curve. A compendium of 38,271 natural products originating from Africa and China together with eleven known p38 MAPK inhibitors were screened against the receptor. Four potential lead compounds ZINC1691180, ZINC5519433, ZINC4520996 and ZINC5733756 were identified. The compounds formed strong intermolecular bonds with critical residues Val38, Ala51, Lys53, Thr106, Leu108, Met109 and Phe169. Additionally, they exhibited appreciably low binding energies which were corroborated via molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) calculations. The compounds were also predicted to have plausible pharmacological profiles with insignificant toxicity. The molecules were also predicted to be anti-inflammatory, kinase inhibitors, antiviral, platelet aggregation inhibitors, and immunosuppressive, with probable activity (Pa) greater than probable inactivity (Pi). ZINC5733756 is structurally similar to estradiol with a Tanimoto coefficient value of 0.73, which exhibits anti-inflammatory activity by targeting the activation of Nrf2. Similarly, ZINC1691180 has been reported to elicit anti-inflammatory activity in vitro. The compounds may serve as scaffolds for the design of potential biotherapeutic molecules against the cytokine storm associated with COVID-19.

SARS-CoV-2 entry inhibitors by dual targeting TMPRSS2 and ACE2: An in silico drug repurposing study

The coronavirus disease (COVID-19) is spreading between human populations mainly through nasal droplets. Currently, the vaccines have great hope, but it takes years for testing its efficacy in human. As there is no specific drug treatment available for COVID-19 pandemic, we explored in silico repurposing of drugs with dual inhibition properties by targeting transmembrane serine protease 2 (TMPRSS2) and human angiotensin-converting enzyme 2 (ACE2) from FDA-approved drugs. The TMPRSS2 and ACE2 dual inhibitors in COVID-19 would be a novel antiviral class of drugs called “entry inhibitors.” For this purpose, approximately 2800 US-FDA approved drugs were docked using a virtual docking tool with the targets TMPRSS2 and ACE2. The best-fit drugs were selected as per docking scores and visual outcomes. Later on, drugs were selected on the basis of molecular dynamics simulations. The drugs alvimopan, arbekacin, dequalinum, fleroxacin, lopinavir, and valrubicin were shortlisted by visual analysis and molecular dynamics simulations. Among these, lopinavir and valrubicin were found to be superior in terms of dual inhibition. Thus, lopinavir and valrubicin have the potential of dual-target inhibition whereby preventing SARS-CoV-2 entry to the host. For repurposing of these drugs, further screening in vitro and in vivo would help in exploring clinically.

The Role and Therapeutic Potential of NF-kappa-B Pathway in Severe COVID-19 Patients

Coronavirus disease 2019 (COVID-19) pandemic has affected health care systems worldwide. Severe presentations of COVID-19 such as severe pneumonia and acute respiratory distress syndrome (ARDS) have been associated with the post-viral activation and release of cytokine/chemokines which leads to a "cytokine storm" causing inflammatory response and destruction, mainly affecting the lungs. COVID-19 activation of transcription factor, NF-kappa B (NF-κB) in various cells such as macrophages of lung, liver, kidney, central nervous system, gastrointestinal system and cardiovascular system leads to production of IL-1, IL-2, IL-6, IL-12, TNF-α, LT-α, LT-β, GM-CSF, and various chemokines. The sensitised NF-κB in elderly and in patients with metabolic syndrome makes this set of population susceptible to COVID-19 and their worse complications, including higher mortality. Immunomodulation at the level of NF-κB activation and inhibitors of NF-κB (IκB) degradation along with TNF-α inhibition will potentially result in a reduction in the cytokine storm and alleviate the severity of COVID-19. Inhibition of NF-κB pathway has a potential therapeutic role in alleviating the severe form of COVID-19.

Dysregulation of Angiotensin Converting Enzyme 2 Expression and Function in Comorbid Disease Conditions Possibly Contributes to Coronavirus Infectious Disease 2019 Complication Severity

ACE2 has emerged as a double agent in the COVID-19 ordeal, as it is both physiologically protective and virally conducive. The identification of ACE2 in as many as 72 tissues suggests that extrapulmonary invasion and damage is likely, which indeed has already been demonstrated by cardiovascular and gastrointestinal symptoms. On the other hand, identifying ACE2 dysregulation in patients with comorbidities may offer insight as to why COVID-19 symptoms are often more severe in these individuals. This may be attributed to a pre-existing proinflammatory state that is further propelled with the cytokine storm induced by SARS-CoV-2 infection or the loss of functional ACE2 expression as a result of viral internalization. Here, we aim to characterize the distribution and role of ACE2 in various organs to highlight the scope of damage that may arise upon SARS-CoV-2 invasion. Furthermore, by examining the disruption of ACE2 in several comorbid diseases, we offer insight into potential causes of increased severity of COVID-19 symptoms in certain individuals. SIGNIFICANCE STATEMENT: Cell surface expression of ACE2 determines the tissue susceptibility for coronavirus infectious disease 2019 infection. Comorbid disease conditions altering ACE2 expression could increase the patient's vulnerability for the disease and its complications, either directly, through modulation of viral infection, or indirectly, through alteration of inflammatory status.

Subcellular hot spots of GPCR signaling promote vascular inflammation

G-coupled protein receptors (GPCRs) comprise the largest class of druggable targets. Signaling by GPCRs is initiated from subcellular hot spots including the plasma membrane, signalosomes, and endosomes to contribute to vascular inflammation. GPCR-G protein signaling at the plasma membrane causes endothelial barrier disruption and also cross-talks with growth factor receptors to promote proinflammatory signaling. A second surge of GPCR signaling is initiated by cytoplasmic NFκB activation mediated by β-arrestins and CARMA-BCL10-MALT1 signalosomes. Once internalized, ubiquitinated GPCRs initiate signaling from endosomes via assembly of the transforming growth factor-β-activated kinase binding protein-1 (TAB1)-TAB2-p38 MAPK complex to promote vascular inflammation. Understanding the complexities of GPCR signaling is critical for development of new strategies to treat vascular inflammation such as that associated with COVID-19.

p38 MAPK inhibition: A promising therapeutic approach for COVID-19

COVID-19, caused by the SARS-CoV-2 virus, is a major source of morbidity and mortality due to its inflammatory effects in the lungs and heart. The p38 MAPK pathway plays a crucial role in the release of pro-inflammatory cytokines such as IL-6 and has been implicated in acute lung injury and myocardial dysfunction. The overwhelming inflammatory response in COVID-19 infection may be caused by disproportionately upregulated p38 activity, explained by two mechanisms. First, angiotensin-converting enzyme 2 (ACE2) activity is lost during SARS-CoV-2 viral entry. ACE2 is highly expressed in the lungs and heart and converts Angiotensin II into Angiotensin 1-7. Angiotensin II signals proinflammatory, pro-vasoconstrictive, pro-thrombotic activity through p38 MAPK activation, which is countered by Angiotensin 1-7 downregulation of p38 activity. Loss of ACE2 upon viral entry may tip the balance towards destructive p38 signaling through Angiotensin II. Second, SARS-CoV was previously shown to directly upregulate p38 activity via a viral protein, similar to other RNA respiratory viruses that may hijack p38 activity to promote replication. Given the homology between SARS-CoV and SARS-CoV-2, the latter may employ a similar mechanism. Thus, SARS-CoV-2 may induce overwhelming inflammation by directly activating p38 and downregulating a key inhibitory pathway, while simultaneously taking advantage of p38 activity to replicate. Therapeutic inhibition of p38 could therefore attenuate COVID-19 infection. Interestingly, a prior preclinical study showed protective effects of p38 inhibition in a SARS-CoV mouse model. A number of p38 inhibitors are in the clinical stage and should be considered for clinical trials in serious COVID-19 infection.

Role of the Immune System in Hypertension

High blood pressure is present in more than one billion adults worldwide and is the most important modifiable risk factor of death resulting from cardiovascular disease. While many factors contribute to the pathogenesis of hypertension, a role of the immune system has been firmly established by a large number of investigations from many laboratories around the world. Immunosuppressive drugs and inhibition of individual cytokines prevent or ameliorate experimental hypertension, and studies in genetically-modified mouse strains have demonstrated that lymphocytes are necessary participants in the development of hypertension and in hypertensive organ injury. Furthermore, immune reactivity may be the driving force of hypertension in autoimmune diseases. Infiltration of immune cells, oxidative stress, and stimulation of the intrarenal angiotensin system are induced by activation of the innate and adaptive immunity. High blood pressure results from the combined effects of inflammation-induced impairment in the pressure natriuresis relationship, dysfunctional vascular relaxation, and overactivity of the sympathetic nervous system. Imbalances between proinflammatory effector responses and anti-inflammatory responses of regulatory T cells to a large extent determine the severity of inflammation. Experimental and human studies have uncovered autoantigens (isoketal-modified proteins and heat shock protein 70) of potential clinical relevance. Further investigations on the immune reactivity in hypertension may result in the identification of new strategies for the treatment of the disease.

Circulating TNF receptors predict cardiovascular disease in patients with chronic kidney disease

Cardiovascular disease (CVD) is the main public health problem in patients with chronic kidney disease (CKD); however, there is no established biomarker for predicting CVD morbidity and mortality in CKD. The aim of this study was to evaluate the role of circulating tumor necrosis factor receptors (cTNFRs) in predicting CVD risk in CKD patients.We prospectively recruited 984 patients with CKD from 11 centers between 2006 and 2012. The levels of cTNFR1 and cTNFR2 were determined by performing an enzyme-linked immunosorbent assay. During the mean follow-up period of 4 years, 36 patients experienced a CVD event. The median serum concentrations of cTNFR1 and cTNFR2 were 2703.4 (225.6-13,057.7) and 5661.0 (634.9-30,599.6) pg/mL, respectively, and the cTNFR1 level was closely correlated with the cTNFR2 level (r = 0.86, P < .0001). The urinary protein-to-creatinine ratio (UPCR) and estimated glomerular filtration rate (eGFR) were significantly correlated with the cTNFR2 level (r = 0.21 for UPCR, r = -0.67 for eGFR; P < .001 for all). Similar correlations were observed for serum cTNFR1 (r = 0.21 for UPCR, r = -0.75 for eGFR; P < .001 for all). In the Cox proportional hazard analyses, cTNFR1 (hazard ratio [HR] 2.506, 95% confidence interval [CI] 1.186-5.295, P = .016) and cTNFR2 (HR 4.156, 95% CI 1.913-9.030, P < .001) predicted CVD risk even after adjustment for clinical covariates, such as UPCR, eGFR, and high-sensitivity C-reactive protein. cTNFR1 and 2 are associated with CVD and other risk factors in CKD, independently of eGFR and UPCR. Furthermore, cTNFRs could be relevant predictors of CVD in CKD patients.

ACE2 and the Homolog Collectrin in the Modulation of Nitric Oxide and Oxidative Stress in Blood Pressure Homeostasis and Vascular Injury

SIGNIFICANCE

Hypertension is the leading risk factor causing mortality and morbidity worldwide. Angiotensin (Ang) II, the most active metabolite of the renin-angiotensin system, plays an outstanding role in the pathogenesis of hypertension and vascular injury. Activation of angiotensin converting enzyme 2 (ACE2) has shown to attenuate devastating effects of Ang II in the cardiovascular system by reducing Ang II degradation and increasing Ang-(1-7) generation leading to Mas receptor activation. Recent Advances: Activation of the ACE2/Ang-(1-7)/Mas receptor axis reduces hypertension and improves vascular injury mainly through an increased nitric oxide (NO) bioavailability and decreased reactive oxygen species production. Recent studies reported that shedding of the enzymatically active ectodomain of ACE2 from the cell surface seems to regulate its activity and serves as an interorgan communicator in cardiovascular disease. In addition, collectrin, an ACE2 homolog with no catalytic activity, regulates blood pressure through an NO-dependent mechanism.

CRITICAL ISSUES

Large body of experimental data confirmed sustained beneficial effects of ACE2/Ang-(1-7)/Mas receptor axis activation on hypertension and vascular injury. Experimental studies also suggest that activation of collectrin might be beneficial in hypertension and endothelial dysfunction. Their role in clinical hypertension is unclear as selective and reliable activators of both axes are not yet available.

FUTURE DIRECTIONS

This review will highlight the results of recent research progress that illustrate the role of both ACE and collectrin in the modulation of NO and oxidative stress in blood pressure homeostasis and vascular injury, providing evidence for the potential therapeutic application of ACE2 and collectrin in hypertension and vascular disease. Antioxid. Redox Signal. 26, 645-659.

Fibroblast-Specific Genetic Manipulation of p38 Mitogen-Activated Protein Kinase In Vivo Reveals Its Central Regulatory Role in Fibrosis

BACKGROUND

In the heart, acute injury induces a fibrotic healing response that generates collagen-rich scarring that is at first protective but if inappropriately sustained can worsen heart disease. The fibrotic process is initiated by cytokines, neuroendocrine effectors, and mechanical strain that promote resident fibroblast differentiation into contractile and extracellular matrix-producing myofibroblasts. The mitogen-activated protein kinase p38α (Mapk14 gene) is known to influence the cardiac injury response, but its direct role in orchestrating programmed fibroblast differentiation and fibrosis in vivo is unknown.

METHODS

A conditional Mapk14 allele was used to delete the p38α encoding gene specifically in cardiac fibroblasts or myofibroblasts with 2 different tamoxifen-inducible Cre recombinase-expressing gene-targeted mouse lines. Mice were subjected to ischemic injury or chronic neurohumoral stimulation and monitored for survival, cardiac function, and fibrotic remodeling. Antithetically, mice with fibroblast-specific transgenic overexpression of activated mitogen-activated protein kinase kinase 6, a direct inducer of p38, were generated to investigate whether this pathway can directly drive myofibroblast formation and the cardiac fibrotic response.

RESULTS

In mice, loss of Mapk14 blocked cardiac fibroblast differentiation into myofibroblasts and ensuing fibrosis in response to ischemic injury or chronic neurohumoral stimulation. A similar inhibition of myofibroblast formation and healing was also observed in a dermal wounding model with deletion of Mapk14. Transgenic mice with fibroblast-specific activation of mitogen-activated protein kinase kinase 6-p38 developed interstitial and perivascular fibrosis in the heart, lung, and kidney as a result of enhanced myofibroblast numbers. Mechanistic experiments show that p38 transduces cytokine and mechanical signals into myofibroblast differentiation through the transcription factor serum response factor and the signaling effector calcineurin.

CONCLUSIONS

These findings suggest that signals from diverse modes of injury converge on p38α mitogen-activated protein kinase within the fibroblast to program the fibrotic response and myofibroblast formation in vivo, suggesting a novel therapeutic approach with p38 inhibitors for future clinical application.

Chronic p38 mitogen-activated protein kinase inhibition improves vascular function and remodeling in angiotensin II-dependent hypertension

Introduction:

An excess of angiotensin II (Ang II) causes hypertension and vascular injury. Activation of mitogen-activated protein kinase p38 (p38-MAPK) plays a substantial role in Ang II-dependent organ damage. Recently, we showed that p38-MAPK activation regulates the pressor response to Ang II. This study evaluates the effect of chronic p38-MAPK inhibition in Ang II-dependent hypertension.

Materials and methods:

C57Bl/6J mice were infused with Ang II for 14 days and either treated with the p38-MAPK inhibitor BIRB796 (50 mg/kg/day) or the vehicle as the control. We assessed vascular function in the aorta and isolated perfused kidneys.

Results:

Chronic p38-MAPK inhibition did not alter blood pressure at the baseline, but attenuated Ang II-induced hypertension significantly (baseline: 122 ± 2 versus 119 ± 4 mmHg; Ang II: 173 ± 3 versus 155 ± 3 mmHg; p < 0.001). In addition, BIRB796 treatment improved vascular remodeling by reducing the aortic media-to-lumen ratio and decreasing the expression of the membrane metalloproteinases (MMP) MMP-1 and MMP-9. Moreover, renal vascular dysfunction induced by chronic Ang II infusion was significantly ameliorated in the BIRP796-treated mice. Acute p38-MAPK inhibition also improved vascular function in the aorta and kidneys of Ang II-treated mice, highlighting the important role of p38-MAPK activation in the pathogenesis of vascular dysfunction.

Conclusions:

Our findings indicated there is an important role for p38-MAPK in regulating blood pressure and vascular injury, and highlighted its potential as a pharmaceutical target.

p38 MAPK Inhibition Improves Synaptic Plasticity and Memory in Angiotensin II-dependent Hypertensive Mice

The pathogenesis of hypertension-related cognitive impairment has not been sufficiently clarified, new molecular targets are needed. p38 MAPK pathway plays an important role in hypertensive target organ damage. Activated p38 MAPK was seen in AD brain tissue. In this study, we found that long-term potentiation (LTP) of hippocampal CA1 was decreased, the density of the dendritic spines on the CA1 pyramidal cells was reduced, the p-p38 protein expression in hippocampus was elevated, and cognitive function was impaired in angiotensin II-dependent hypertensive C57BL/6 mice. In vivo, using a p38 heterozygous knockdown mice (p38(KI/+)) model, we showed that knockdown of p38 MAPK in hippocampus leads to the improvement of cognitive function and hippocampal synaptic plasticity in angiotensin II-dependent p38(KI/+) hypertensive mice. In vitro, LTP was improved in hippocampal slices from C57BL/6 hypertensive mice by treatment with p38MAPK inhibitor SKF86002. Our data demonstrated that p38 MAPK may be a potential therapeutic target for hypertension-related cognitive dysfunction.

Vascular smooth muscle cell in atherosclerosis

Vascular smooth muscle cells (VSMCs) exhibit phenotypic and functional plasticity in order to respond to vascular injury. In case of the vessel damage, VSMCs are able to switch from the quiescent 'contractile' phenotype to the 'proinflammatory' phenotype. This change is accompanied by decrease in expression of smooth muscle (SM)-specific markers responsible for SM contraction and production of proinflammatory mediators that modulate induction of proliferation and chemotaxis. Indeed, activated VSMCs could efficiently proliferate and migrate contributing to the vascular wall repair. However, in chronic inflammation that occurs in atherosclerosis, arterial VSMCs become aberrantly regulated and this leads to increased VSMC dedifferentiation and extracellular matrix formation in plaque areas. Proatherosclerotic switch in VSMC phenotype is a complex and multistep mechanism that may be induced by a variety of proinflammatory stimuli and hemodynamic alterations. Disturbances in hemodynamic forces could initiate the proinflammatory switch in VSMC phenotype even in pre-clinical stages of atherosclerosis. Proinflammatory signals play a crucial role in further dedifferentiation of VSMCs in affected vessels and propagation of pathological vascular remodelling.

Vitamin D depletion aggravates hypertension and target-organ damage

Background

We tested the controversial hypothesis that vitamin D depletion aggravates hypertension and target‐organ damage by influencing renin.

Methods and Results

Four‐week‐old double‐transgenic rats (dTGR) with excess angiotensin (Ang) II production due to overexpression of the human renin (hREN) and angiotensinogen (hAGT) genes received vitamin D‐depleted (n=18) or standard chow (n=15) for 3 weeks. The depleted group had very low serum 25‐hydroxyvitamin D levels (mean±SEM; 3.8±0.29 versus 40.6±1.19 nmol/L) and had higher mean systolic BP at week 5 (158±3.5 versus 134.6±3.7 mm Hg, P<0.001), week 6 (176.6±3.3 versus 162.3±3.8 mm Hg, P<0.01), and week 7 (171.6±5.1 versus 155.9±4.3 mm Hg, P<0.05). Vitamin D depletion led to increased relative heart weights and increased serum creatinine concentrations. Furthermore, the mRNAs of natriuretic peptides, neutrophil gelatinase‐associated lipocalin, hREN, and rRen were increased by vitamin D depletion. Regulatory T cells in the spleen and in the circulation were not affected. Ang metabolites, including Ang II and the counter‐regulatory breakdown product Ang 1 to 7, were significantly up‐regulated in the vitamin D‐depleted groups, while ACE‐1 and ACE‐2 activities were not affected.

Conclusions

Short‐term severe vitamin D depletion aggravated hypertension and target‐organ damage in dTGR. Our data suggest that even short‐term severe vitamin D deficiency may directly promote hypertension and impacts on renin‐angiotensin system components that could contribute to target‐organ damage. The findings add to the evidence that vitamin D deficiency could also affect human hypertension.

Protection from renal fibrosis, putative role of TRIB3 gene silencing

BACKGROUND

Renal fibrosis is thought to be the common pathway in most cases of chronic kidney disease. Recently, TRIB3 was found to play an important role in progression of cardiac fibrosis in an insulin-resistant state. We investigated whether TRIB3 might participate in the pathogenesis of renal fibrosis in insulin-resistant rats.

METHODS

We randomly separated 40 male Sprague-Dawley into 4 groups for treatment (n = 10 each): control and high-fat diet (HFD) with TRIB3 siRNA adenovirus transfection, vehicle transfection or HFD alone. Insulin resistance markers were measured. Renal tissues were stained with hematoxylin and eosin, Masson's trichrome and periodic acid-Schiff.

RESULTS

Rats with HFD showed insulin resistance and TRIB3 overexpression. Upregulated TRIB3 expression could induce renal fibrosis accompanied by increased phosphorylation of extracellular signal-regulated kinase (ERK). Also, TRIB3 siRNA knockdown could ameliorate renal fibrosis, which was accompanied by decreased phosphorylation of ERK.

CONCLUSIONS

TRIB3 gene silencing can attenuate renal fibrosis for beneficial effect on the development of renal fibrosis in chronic kidney disease in rat.

Inflammation and mechanical stretch promote aortic stiffening in hypertension through activation of p38 mitogen-activated protein kinase

RATIONALE

Aortic stiffening commonly occurs in hypertension and further elevates systolic pressure. Hypertension is also associated with vascular inflammation and increased mechanical stretch. The interplay between inflammation, mechanical stretch, and aortic stiffening in hypertension remains undefined.

OBJECTIVE

Our aim was to determine the role of inflammation and mechanical stretch in aortic stiffening.

METHODS AND RESULTS

Chronic angiotensin II infusion caused marked aortic adventitial collagen deposition, as quantified by Masson trichrome blue staining and biochemically by hydroxyproline content, in wild-type but not in recombination activating gene-1-deficient mice. Aortic compliance, defined by ex vivo measurements of stress-strain curves, was reduced by chronic angiotensin II infusion in wild-type mice (P<0.01) but not in recombination activating gene-1-deficient mice (P<0.05). Adoptive transfer of T-cells to recombination activating gene-1-deficient mice restored aortic collagen deposition and stiffness to values observed in wild-type mice. Mice lacking the T-cell-derived cytokine interleukin 17a were also protected against aortic stiffening. In additional studies, we found that blood pressure normalization by treatment with hydralazine and hydrochlorothiazide prevented angiotensin II-induced vascular T-cell infiltration, aortic stiffening, and collagen deposition. Finally, we found that mechanical stretch induces the expression of collagen 1α1, 3α1, and 5a1 in cultured aortic fibroblasts in a p38 mitogen-activated protein kinase-dependent fashion, and that inhibition of p38 prevented angiotensin II-induced aortic stiffening in vivo. Interleukin 17a also induced collagen 3a1 expression via the activation of p38 mitogen-activated protein kinase.

CONCLUSIONS

Our data define a pathway in which inflammation and mechanical stretch lead to vascular inflammation that promotes collagen deposition. The resultant increase in aortic stiffness likely further worsens systolic hypertension and its attendant end-organ damage.

Upregulation of M₃ muscarinic receptor inhibits cardiac hypertrophy induced by angiotensin II

BACKGROUND

M₃ muscarinic acetylcholine receptor (M₃-mAChR) is stably expressed in the myocardium, but its pathophysiological role remains largely undefined. This study aimed to investigate the role of M₃-mAChR in cardiac hypertrophy induced by angiotensin II (Ang II) and elucidate the underlying mechanisms.

METHODS

Cardiac-specific M₃-mAChR overexpression transgenic (TG) mice and rat H9c2 cardiomyoblasts with ectopic expression of M₃-mAChR were established. Models of cardiac hypertrophy were induced by transverse aortic constriction (TAC) or Ang II infusion in the mice in vivo, and by isoproterenol (ISO) or Ang II treatment of H9c2 cells in vitro. Cardiac hypertrophy was evaluated by electrocardiography (ECG) measurement, hemodynamic measurement and histological analysis. mRNA and protein expression were detected by real-time RT-PCR and Western blot analysis.

RESULTS

M₃-mAChR was upregulated in hypertrophic heart, while M₂-mAChR expression did not change significantly. M₃-mAChR overexpression significantly attenuated the increased expression of atrial natriuretic peptide and β-myosin heavy chain induced by Ang II both in vivo and in vitro. In addition, M₃-mAChR overexpression downregulated AT1 receptor expression and inhibited the activation of MAPK signaling in the heart.

CONCLUSION

The upregulation of M₃-mAChR during myocardial hypertrophy could relieve the hypertrophic response provoked by Ang II, and the mechanism may involve the inhibition of MAPK signaling through the downregulation of AT1 receptor.

Inhibition of p38 MAPK attenuates renal atrophy and fibrosis in a murine renal artery stenosis model

Renal artery stenosis (RAS) is an important cause of chronic renal dysfunction. Recent studies have underscored a critical role for CCL2 (MCP-1)-mediated inflammation in the progression of chronic renal damage in RAS and other chronic renal diseases. In vitro studies have implicated p38 MAPK as a critical intermediate for the production of CCL2. However, a potential role of p38 signaling in the development and progression of chronic renal disease in RAS has not been previously defined. We sought to test the hypothesis that inhibition of p38 MAPK ameliorates chronic renal injury in mice with RAS. We established a murine RAS model by placing a cuff on the right renal artery and treated mice with the p38 inhibitor SB203580 or vehicle for 2 wk. In mice treated with vehicle, the cuffed kidney developed interstitial fibrosis, tubular atrophy, and interstitial inflammation. In mice treated with SB203580, the RAS-induced renal atrophy was reduced (70% vs. 39%, P < 0.05). SB203580 also reduced interstitial inflammation and extracellular matrix deposition but had no effect on the development of hypertension. SB203580 partially blocked the induction of CCL2, CCL7 (MCP-3), CC chemokine receptor 2 (CCR2), and collagen 4 mRNA expression in the cuffed kidneys. In vitro, blockade of p38 hindered both TNF-α and TGF-β-induced CCL2 upregulation. Based on these observations, we conclude that p38 MAPK plays a critical role in the induction of CCL2/CCL7/CCR2 system and the development of interstitial inflammation in RAS.

Caveolin and β1-integrin coordinate angiotensinogen expression in cardiac myocytes

BACKGROUND

The cardiac renin-angiotensin system (RAS) has been implicated in mediating myocyte hypertrophy and remodeling, although the biochemical mechanisms responsible for regulating the local RAS are poorly understood. Caveolin-1 (Cav-1)/Cav-3 double-knockout mice display cardiac hypertrophy, and in vitro disruption of lipid rafts/caveolae using methyl-β-cyclodextrin (MβCD) abolishes cardiac protection.

METHODS

In this study, neonatal rat ventricular myocytes (NRVM) were used to determine whether lipid rafts/caveolae may be involved in the regulation of angiotensinogen (Ao) gene expression, a substrate of the RAS system.

RESULTS

Treatment with MβCD caused a time-dependent upregulation of Ao gene expression, which was associated with differential regulation of mitogen-activated protein (MAP) kinases ERK1/2, p38 and JNK phosphorylation. JNK was highly phosphorylated shortly after MβCD treatment (2-30 min), whereas marked activation of ERK1/2 and p38 occurred much later (2-4h). β1D-Integrin was required for MβCD-induced activation of the MAP kinases. Pharmacologic inhibition of ERK1/2 and JNK enhanced MβCD-induced Ao gene expression, whereas p38 blockade inhibited this response. Adenovirus-mediated expression of wild-type p38α enhanced MβCD-induced Ao gene expression; conversely expression of dominant negative p38α blocked the stimulatory effects of MβCD. Expression of Cav-3 siRNA stimulated Ao gene expression, whereas overexpression of Cav-3 was inhibitory. Cav-1 and Cav-3 expression levels were found to be positively regulated by p38, but unaffected by ERK1/2 and JNK.

CONCLUSION

Collectively, these studies indicate that lipid rafts/caveolae couple to Ao gene expression through a mechanism that involves β1-integrin and the differential actions of MAP kinase family members.

Choline inhibits angiotensin II-induced cardiac hypertrophy by intracellular calcium signal and p38 MAPK pathway

Choline, an agonist of M(3) muscarinic acetylcholine receptors, is a precursor and metabolite of acetylcholine and is also a functional modulator of cellular membrane. However, the effect of choline on cardiac hypertrophy is not fully understood. The present study was therefore designed to explore whether choline could prevent cardiac hypertrophy induced by angiotensin II (Ang II) and clarify its potential mechanisms. Cardiac hypertrophy was induced by 0.6 mg kg(-1) day(-1) Ang II for 2 weeks in the presence or absence of choline pretreatment, while cardiomyocyte hypertrophy was induced by Ang II 0.1 μM for 48 h. We found that choline pretreatment attenuated the increment cell size of cardiomyocytes induced by Ang II both in vivo and in vitro. The high ANP and β-MHC levels induced by Ang II were also reversed by choline in cardiomyocytes. Meanwhile, choline pretreatment prevented the augment of reactive oxygen species (ROS) and intracellular calcium concentration in Ang II-treated cardiomyocytes. Furthermore, the upregulated phospho-p38 mitogen-activated protein kinase (MAPK) and calcineurin levels by Ang II in ventricular myocytes were attenuated by choline. In conclusion, choline prevents Ang II-induced cardiac hypertrophy through inhibition of ROS-mediated p38 MAPK activation as well as regulation of Ca(2+)-mediated calcineurin signal transduction pathway. Our results provide new insights into the pharmacological role of choline in cardiovascular diseases.

BMP-9 induced endothelial cell tubule formation and inhibition of migration involves Smad1 driven endothelin-1 production

BACKGROUND

Bone morphogenetic proteins (BMPs) and their receptors, such as bone morphogenetic protein receptor (BMPR) II, have been implicated in a wide variety of disorders including pulmonary arterial hypertension (PAH). Similarly, endothelin-1 (ET-1), a mitogen and vasoconstrictor, is upregulated in PAH and endothelin receptor antagonists are used in its treatment. We sought to determine whether there is crosstalk between BMP signalling and the ET-1 axis in human pulmonary artery endothelial cells (HPAECs), possible mechanisms involved in such crosstalk and functional consequences thereof.

METHODOLOGY/PRINCIPAL FINDING

Using western blot, real time RT-PCR, ELISA and small RNA interference methods we provide evidence that in HPAECs BMP-9, but not BMP-2, -4 and -6 significantly stimulated ET-1 release under physiological concentrations. This release is mediated by both Smad1 and p38 MAPK and is independent of the canonical Smad4 pathway. Moreover, knocking down the ALK1 receptor or BMPR II attenuates BMP-9 stimulated ET-1 release, whilst causing a significant increase in prepro ET-1 mRNA transcription and mature peptide release. Finally, BMP-9 induced ET-1 release is involved in both inhibition of endothelial cell migration and promotion of tubule formation.

CONCLUSIONS/SIGNIFICANCE

Although our data does not support an important role for BMP-9 as a source of increased endothelial ET-1 production seen in human PAH, BMP-9 stimulated ET-1 production is likely to be important in angiogenesis and vascular stability. However, increased ET-1 production by endothelial cells as a consequence of BMPR II dysfunction may be clinically relevant in the pathogenesis of PAH.

Study on the protective effect of shengmai san (see text) on the myocardium in the type 2 diabetic cardiomyopathy model rat

OBJECTIVE

To study the effect of Shengmai San ((see text) Pulse-activating Powder) in protecting myocardium in the rat of the type 2 diabetic cardiomyopathy (DCM) model.

METHODS

The DCM rat model was established by combination of insulin resistance induced by a high-fat diet with intraperitoneal injection of high dose streptozotocin (50 mg/kg). And these rat models were randomly divided into three groups: a normal group (n = 12,one of them died), a model group (n = 15) and a Shengmai San group (treatment group, n = 15).The damage of the myocardium was assessed by electrocardiogram at the twelfth week after modeling, and the blood glucose, cholesterol and triglyceride levels were determined; the content of the left cardiac ventricle myocardial collagen was quantified by Masson staining test; the level of myocardial cell apoptosis was detected with TUNEL apoptosis detection kit; the damage extent of the myocardial sub-cellular structures was observed by electron microscopy; the expression levels of cardiac TSP-1 (Thrombospondin-1), TGF-beta1 (Transforming Growth F factor-beta) and TRB-3 (Tribbles homolog 3) proteins were detected by immunohistochemical method; the expression levels of cardiac TSP-1, A-TGF-beta1 and L-TGF-beta1 proteins were detected by Western blotting; and the expression levels of TSP-1 and TRB-3 mRNAs were detected by real-time quantitative PCR.

RESULTS

Compared with the control group, the blood glucose, cholesterol, triglycerides levels in both the model groups and the Shengmai San group were significantly decreased; the myocardial tissue was less damaged and the collagen content was reduced in the Shengmai San group; the myocardial sub-cellular structure was injured to a lesser extent; the expression levels of myocardial TSP-1, TGF-beta1, TRB-3, and TSP-1, A-TGF-beta1, L-TGF-beta1 and chymase were decreased, and the expression levels of TSP-1 mRNA and TRB-3 mRNA were decreased in both the model groups and the Shengmai San group (the latter was better),.

CONCLUSION

Shengmai San can inhibit myocardial fibrosis in the rat of diabetic cardiomyopathy, and significantly delay the formation of diabetic cardiomyopathy in hyperglycemia rats through multiple pathways.

Angiotensin II-induced vascular endothelial dysfunction through RhoA/Rho kinase/p38 mitogen-activated protein kinase/arginase pathway

Enhanced vascular arginase activity impairs endothelium-dependent vasorelaxation by decreasing l-arginine availability to endothelial nitric oxide (NO) synthase, thereby reducing NO production. Elevated angiotensin II (ANG II) is a key component of endothelial dysfunction in many cardiovascular diseases and has been linked to elevated arginase activity. We determined signaling mechanisms by which ANG II increases endothelial arginase function. Results show that ANG II (0.1 μM, 24 h) elevates arginase activity and arginase I expression in bovine aortic endothelial cells (BAECs) and decreases NO production. These effects are prevented by the arginase inhibitor BEC (100 μM). Blockade of ANG II AT(1) receptors or transfection with small interfering RNA (siRNA) for Gα12 and Gα13 also prevents ANG II-induced elevation of arginase activity, but siRNA for Gαq does not. ANG II also elevates active RhoA levels and induces phosphorylation of p38 MAPK. Inhibitors of RhoA activation (simvastatin, 0.1 μM) or Rho kinase (ROCK) (Y-27632, 10 μM; H1152, 0.5 μM) block both ANG II-induced elevation of arginase activity and phosphorylation of p38 MAPK. Furthermore, pretreatment of BAECs with p38 inhibitor SB-202190 (2 μM) or transfection with p38 MAPK siRNA prevents ANG II-induced increased arginase activity/expression and maintains NO production. Additionally, inhibitors of p38 MAPK (SB-203580, 5 μg·kg(-1)·day(-1)) or arginase (ABH, 8 mg·kg(-1)·day(-1)) or arginase gene knockout in mice prevents ANG II-induced vascular endothelial dysfunction and associated enhancement of arginase. These results indicate that ANG II increases endothelial arginase activity/expression through Gα12/13 G proteins coupled to AT(1) receptors and subsequent activation of RhoA/ROCK/p38 MAPK pathways leading to endothelial dysfunction.

Cardiac-Specific Activation of Angiotensin II Type 1 Receptor–Associated Protein Completely Suppresses Cardiac Hypertrophy in Chronic Angiotensin II–Infused Mice

We cloned a novel molecule interacting with angiotensin II type 1 receptor, which we named ATRAP (for angiotensin II type 1 receptor–associated protein). Previous in vitro studies showed that ATRAP significantly promotes constitutive internalization of the angiotensin II type 1 receptor and further attenuates angiotensin II–mediated hypertrophic responses in cardiomyocytes. The present study was designed to investigate the putative functional role of ATRAP in cardiac hypertrophy by angiotensin II infusion in vivo. We first examined the effect of angiotensin II infusion on endogenous ATRAP expression in the heart of C57BL/6J wild-type mice. The angiotensin II treatment promoted cardiac hypertrophy, concomitant with a significant decrease in cardiac ATRAP expression, but without significant change in cardiac angiotensin II type 1 receptor expression. We hypothesized that a downregulation of the cardiac ATRAP to angiotensin II type 1 receptor ratio is involved in the pathogenesis of cardiac hypertrophy. To examine this hypothesis, we next generated transgenic mice expressing ATRAP specifically in cardiomyocytes under control of the α-myosin heavy chain promoter. In cardiac-specific ATRAP transgenic mice, the development of cardiac hypertrophy, activation of p38 mitogen-activated protein kinase, and expression of hypertrophy-related genes in the context of angiotensin II treatment were completely suppressed, in spite of there being no significant difference in blood pressure on radiotelemetry between the transgenic mice and littermate control mice. These results demonstrate that cardiomyocyte-specific overexpression of ATRAP in vivo abolishes the cardiac hypertrophy provoked by chronic angiotensin II infusion, thereby suggesting ATRAP to be a novel therapeutic target in cardiac hypertrophy.

Tissue renin-angiotensin-aldosterone systems: Targets for pharmacological therapy

The renin-angiotensin-aldosterone system is one of the most important systems in cardiovascular control and in the pathogenesis of cardiovascular diseases. Therefore, it is already a very successful drug target for the therapy of these diseases. However, angiotensins are generated not only in the plasma but also locally in tissues from precursors and substrates either locally expressed or imported from the circulation. In most areas of the brain, only locally generated angiotensins can exert effects on their receptors owing to the blood-brain barrier. Other tissue renin-angiotensin-aldosterone systems are found in cardiovascular organs such as kidney, heart, and vessels and play important roles in the function of these organs and in the deleterious actions of hypertension and diabetes on these tissues. Novel components with mostly opposite actions to the classical renin-angiotensin-aldosterone systems have been described and need functional characterization to evaluate their suitability as novel drug targets.

Molecular mechanisms of chronic kidney transplant rejection via large-scale proteogenomic analysis of tissue biopsies

The most common cause of kidney transplant failure is the poorly characterized histopathologic entity interstitial fibrosis and tubular atrophy (IFTA). There are no known unifying mechanisms, no effective therapy, and no proven preventive strategies. Possible mechanisms include chronic immune rejection, inflammation, drug toxicity, and chronic kidney injury from secondary factors. To gain further mechanistic insight, we conducted a large-scale proteogenomic study of kidney transplant biopsies with IFTA of varying severity. We acquired proteomic data using tandem mass spectrometry with subsequent quantification, analysis of differential protein expression, validation, and functional annotations to known molecular networks. We performed genome-wide expression profiling in parallel. More than 1400 proteins with unique expression profiles traced the progression from normal transplant biopsies to biopsies with mild to moderate and severe disease. Multiple sets of proteins were mapped to different functional pathways, many increasing with histologic severity, including immune responses, inflammatory cell activation, and apoptosis consistent with the chronic rejection hypothesis. Two examples include the extensive population of the alternative rather than the classical complement pathway, previously not appreciated for IFTA, and a comprehensive control network for the actin cytoskeleton and cell signaling of the acute-phase response. In summary, this proteomic effort using kidney tissue contributes mechanistic insight into several biologic processes associated with IFTA.

Small but powerful: short peptide hormones and their role in autoimmune inflammation

In the recent years, it has become increasingly clear that the immune response is also influenced by mediators which were first discovered as regulators in the nervous or also cardiovascular system. Here, small peptide hormones may play an important role. Kinins like bradykinins act on the endothelium and play a role for trafficking of lymphocytes over the blood-brain barrier. Neuropeptides like vasoactive intestinal peptide or neuropeptide Y also directly act on T cells and favour the differentiation of Th2 cells or regulatory T cell populations. Recently, the renin-angiotensin system (RAS) came into the focus of interest. Inhibition of the RAS at different levels may influence autoimmune responses and involve T cells as well as antigen-presenting cells, probably via different signalling pathways. Inhibitors of angiotensin converting enzyme and antagonists of the angiotensin 1 receptors are used in the treatment of hypertension, kidney disease or stroke by millions of people worldwide. These inexpensive and safe pharmaceuticals may also represent an interesting and innovative approach for the (combination) treatment of autoimmune diseases like multiple sclerosis.

Differential effects of p38 mitogen-activated protein kinase and cyclooxygenase 2 inhibitors in a model of cardiovascular disease

The evidence is compelling for a role of inflammation in cardiovascular diseases; however, the chronic use of anti-inflammatory drugs for these indications has been disappointing. The recent study compares the effects of two anti-inflammatory agents [cyclooxygenase 2 (COX2) and p38 inhibitors] in a model of cardiovascular disease. The vascular, renal, and cardiac effects of 4-(4-methylsulfonylphenyl)-3-phenyl-5H-furan-2-one (rofecoxib; a COX2 inhibitor) and 6-{5-[(cyclopropylamino)carbonyl]-3-fluoro-2-methylphenyl}-N-(2,2-dimethylpropyl)-3-pyridinecarboxamide [GSK-AHAB, a selective p38 mitogen-activated protein kinase (MAPK) inhibitor], were examined in the spontaneously hypertensive stroke-prone rat (SHR-SP). In SHR-SPs receiving a salt-fat diet (SFD), chronic treatment with GSK-AHAB significantly and dose-dependently improved survival, endothelial-dependent and -independent vascular relaxation, and indices of renal function, and it attenuated dyslipidemia, hypertension, cardiac remodeling, plasma renin activity (PRA), aldosterone, and interleukin-1beta (IL-1beta). In contrast, chronic treatment with a COX2-selective dose of rofecoxib exaggerated the harmful effects of the SFD, i.e., increasing vascular and renal dysfunction, dyslipidemia, hypertension, cardiac hypertrophy, PRA, aldosterone, and IL-1beta. The protective effects of a p38 MAPK inhibitor are clearly distinct from the deleterious effects of a selective COX2 inhibitor in the SHR-SP and suggest that anti-inflammatory agents can have differential effects in cardiovascular disease. The results also suggest a method for evaluating long-term cardiovascular efficacy and safety.

Soluble tumor necrosis factor receptor 1 level is associated with left ventricular hypertrophy: the northern Manhattan study

BACKGROUND

Although inflammatory markers may be associated with risk of cardiovascular events, few data are available regarding these markers and their association with left ventricular hypertrophy (LVH). We sought to evaluate whether inflammatory markers were independently associated with LVH in a multiethnic population in northern Manhattan.

METHODS

A population-based cross-sectional study was conducted in 660 participants without stroke, who had undergone both transthoracic echocardiography and testing for soluble tumor necrosis factor receptor (sTNFR) 1, interleukin (IL)-6, and high-sensitivity C-reactive protein (hsCRP). LV mass was calculated according to an established formula. LVH was defined as LV mass >90th percentile of the participants.

RESULTS

The mean age was 67.4 +/- 8.8 years, 35.5% were men, 61.7% were Hispanic, 19.7% were black, and 18.6% were white. In univariate analyses, hsCRP, IL-6, and sTNFR1 were significantly associated with LV mass. Multiple linear regression analyses demonstrated that sTNFR1 (P = 0.0008) was associated with LV mass after adjusting for demographic and medical risk factors, but hsCRP and IL-6 were not. When all markers were included in the same model, sTNFR1 remained significant, but hsCRP and IL-6 did not. Compared with the lowest quartile of sTNFR1, those in the highest quartile were more likely to have LVH (odds ratio = 1.84, 95% confidence interval, 0.97-3.64, P = 0.06).

CONCLUSIONS

sTNFR1, but not hsCRP nor IL-6, is independently associated with increased LV mass. Chronic subclinical inflammation including the TNFR1-associated system may contribute to LVH.

Other Transgenic Animal Models Used in Cardiovascular Studies

Previous chapters have described a large number of transgenic animal models used to study specific cardiovascular syndromes. This chapter will fill in some gaps. Many of these transgenic animals were developed to study normal and/or abnormal physiological responses in other organ systems, or to study basic biochemical and molecular reactions or pathways. These models were then discovered to also have effects on the cardiovascular system, some of them unanticipated.

A word of caution, particularly when highly inbred mouse strains are used to develop transgenic models - not all strains of a particular species are created equal. When cardiovascular parameters of age- and sex-matched A/J and C57BL/6J inbred mice were compared the C57BL/6J mice demonstrated eccentric physiologic ventricular hypertrophy, increased ventricular function, lower heart rates, and increased exercise endurance.¹

Stretch-induced regulation of angiotensinogen gene expression in cardiac myocytes and fibroblasts: opposing roles of JNK1/2 and p38alpha MAP kinases

The cardiac renin-angiotensin system (RAS) has been implicated in mediating myocyte hypertrophy, remodeling, and fibroblast proliferation in the hemodynamically overloaded heart. However, the intracellular signaling mechanisms responsible for regulation of angiotensinogen (Ao), a substrate of the RAS system, are largely unknown. Here we report the identification of JNK1/2 as a negative, and p38alpha as a major positive regulator of Ao gene expression. Isolated neonatal rat ventricular myocytes (NRVM) and fibroblasts (NRFB) plated on deformable membranes coated with collagen IV, were exposed to 20% equiaxial static-stretch (0-24 h). Mechanical stretch initially depressed Ao gene expression (4 h), whereas after 8 h, Ao gene expression increased in a time-dependent manner. Blockade of JNK1/2 with SP600125 increased basal Ao gene expression in NRVM (10.52+/-1.98 fold, P<0.001) and NRFB (13.32+/-2.07 fold, P<0.001). Adenovirus-mediated expression of wild-type JNK1 significantly inhibited, whereas expression of dominant-negative JNK1 and JNK2 increased basal and stretch-mediated (24 h) Ao gene expression, showing both JNK1 and JNK2 to be negative regulators of Ao gene expression in NRVM and NRFB. Blockade of p38alpha/beta by SB202190 or p38alpha by SB203580 significantly inhibited stretch-induced (24 h) Ao gene expression, whereas expression of wild-type p38alpha increased stretch-induced Ao gene expression in both NRVM (8.41+/-1.50 fold, P<0.001) and NRFB (3.39+/-0.74 fold, P<0.001). Conversely, expression of dominant-negative p38alpha significantly inhibited stretch response. Moreover, expression of constitutively active MKK6b (E) significantly stimulated Ao gene expression in the absence of stretch, indicating that p38 activation alone is sufficient to induce Ao gene expression. Taken together p38alpha was demonstrated to be a positive regulator, whereas JNK1/2 was found to be a negative regulator of Ao gene expression. Prolonged stretch diminished JNK1/2 activation, which was accompanied by a reciprocal increase in p38 activation and Ao gene expression. This suggests that a balance in JNK1/2 and p38alpha activation determines the level of Ao gene expression in myocardial cells.

Effect of olmesartan on tissue expression balance between angiotensin II receptor and its inhibitory binding molecule

We previously cloned a novel molecule interacting with angiotensin II (Ang II) type 1 receptor protein (ATRAP) and showed it to be an endogenous inhibitor of Ang II type 1 receptor signaling in cardiovascular cells. In this study, we tested a hypothesis that the balance of tissue expression of ATRAP and Ang II type 1 receptor is regulated in a tissue-specific manner during the development of hypertension and related cardiac hypertrophy. Concomitant with blood pressure increase and cardiac hypertrophy in spontaneously hypertensive rats, there was a constitutive decrease in the ratio of cardiac expression of ATRAP to Ang II type 1 receptor. However, treatment with olmesartan, an Ang II type 1 receptor-specific antagonist, either at a depressor or subdepressor dose, recovered the suppressed cardiac ATRAP to Ang II type 1 receptor ratio, which was accompanied by a decrease in Ang II type 1 receptor density, an inhibition of p38 mitogen-activated protein kinase activity, and a regression of cardiac hypertrophy. Furthermore, Ang II stimulation suppressed the ATRAP to Ang II type 1 receptor ratio with hypertrophic responses in both the cardiomyocytes and rat hearts. These findings show a tissue-specific regulatory balancing of the expression of ATRAP and Ang II type 1 receptor during the development of hypertension and cardiac remodeling and further suggest that the upregulation of the tissue ATRAP to Ang II type 1 receptor ratio may be one of the therapeutic benefits of olmesartan beyond its blood pressure-lowering effect.

Pharmacological modulation of epithelial mesenchymal transition caused by angiotensin II. Role of ROCK and MAPK pathways

PURPOSE

Tubulointerstitial fibrosis is a final common pathway to end-stage chronic kidney diseases, which are characterized by elevated renal angiotensin II (AngII) production. This peptide participates in kidney damage inducing fibrosis and epithelial mesenchymal transition (EMT). Our aim was to describe potential therapeutic targets in AngII-induced EMT, investigating the blockade of different intracellular pathways.

METHODS

Studies were done in human tubular epithelial cells (HK2 cell line), evaluating changes in phenotype and EMT markers (Western blot and immunofluorescence).

RESULTS

Treatment of HK2 cells with AngII for 3 days caused transdifferentiation into myofibroblast-like cells. The blockade of MAPKs cascade, using specific inhibitors of p38 (SB203580), extracellular signal-regulated kinase1/2 (ERK; PD98059) and Jun N-terminal kinase (JNK) (SP600125), diminished AngII-induced EMT. The blockade of RhoA/ROCK pathway, by transfection of a RhoA dominant-negative vector or by ROCK inhibition with Y-27632 or fasudil, inhibited EMT caused by AngII. Connective tissue growth factor (CTGF) is a downstream mediator of AngII-induced EMT. MAPKs and ROCK inhibitors blocked CTGF overexpression induced by AngII. HMG-CoA reductase inhibitors, although blocked AngII-mediated kinases activation, only partially diminished EMT and did not regulate CTGF.

CONCLUSIONS

These data suggest a potential therapeutic use of kinase inhibitors in renal fibrosis.

Update on tissue renin-angiotensin systems

Angiotensin (Ang) II is not only generated in the circulation by renin and angiotensin-converting enzyme (ACE) but also is produced locally in numerous organs including kidney, vessels, heart, adrenal gland, eye, testis, and brain. Furthermore, widely distributed mast cells have been shown to be a production site. Local Ang II production process is commonly termed the result of a "tissue" renin-angiotensin system (RAS). Because pharmacological experiments do not easily allow targeting of specific tissues, many novel findings about the functional importance of tissue RAS have been collected from transgenic rodent models. These animals either overexpress or lack RAS components in specific tissues and thereby elucidate their local functions. The data to date show that in most tissues local RAS amplify the actions of circulating Ang II with important implications for physiology and pathophysiology of cardiovascular diseases. This review summarizes the recent findings on the importance of tissue RAS in the most relevant cardiovascular organs.