Protease-activated receptor 1 and 2 contribute to angiotensin II-induced activation of adventitial fibroblasts from rat aorta

Interaction of estradiol and renin-angiotensin system with microRNAs-21 and -29 in renal fibrosis: focus on TGF-β/smad signaling pathway

Kidney fibrosis is one of the complications of chronic kidney disease (CKD (and contributes to end-stage renal disease which requires dialysis and kidney transplantation. Several signaling pathways such as renin-angiotensin system (RAS), microRNAs (miRNAs) and transforming growth factor-β1 (TGF-β1)/Smad have a prominent role in pathophysiology and progression of renal fibrosis. Activation of classical RAS, the elevation of angiotensin II (Ang II) production and overexpression of AT1R, develop renal fibrosis via TGF-β/Smad pathway. While the non-classical RAS arm, Ang 1-7/AT2R, MasR reveals an anti-fibrotic effect via antagonizing Ang II. This review focused on studies illustrating the interaction of RAS with sexual female hormone estradiol and miRNAs in the progression of renal fibrosis with more emphasis on the TGF-β signaling pathway. MiRNAs, especially miRNA-21 and miRNA-29 showed regulatory effects in renal fibrosis. Also, 17β-estradiol (E2) is a renoprotective hormone that improved renal fibrosis. Beneficial effects of ACE inhibitors and ARBs are reported in the prevention of renal fibrosis in patients. Future studies are also merited to delineate the new therapy strategies such as miRNAs targeting, combination therapy of E2 or HRT, ACEis, and ARBs with miRNAs mimics and antagomirs in CKD to provide a new therapeutic approach for kidney patients.

S Protein, ACE2 and Host Cell Proteases in SARS-CoV-2 Cell Entry and Infectivity; Is Soluble ACE2 a Two Blade Sword? A Narrative Review

Since the spread of the deadly virus SARS-CoV-2 in late 2019, researchers have restlessly sought to unravel how the virus enters the host cells. Some proteins on each side of the interaction between the virus and the host cells are involved as the major contributors to this process: (1) the nano-machine spike protein on behalf of the virus, (2) angiotensin converting enzyme II, the mono-carboxypeptidase and the key component of renin angiotensin system on behalf of the host cell, (3) some host proteases and proteins exploited by SARS-CoV-2. In this review, the complex process of SARS-CoV-2 entrance into the host cells with the contribution of the involved host proteins as well as the sequential conformational changes in the spike protein tending to increase the probability of complexification of the latter with angiotensin converting enzyme II, the receptor of the virus on the host cells, are discussed. Moreover, the release of the catalytic ectodomain of angiotensin converting enzyme II as its soluble form in the extracellular space and its positive or negative impact on the infectivity of the virus are considered.

Angiotensin I-converting enzyme inhibitory peptide: an emerging candidate for vascular dysfunction therapy

Abnormal vasoconstriction, inflammation, and vascular remodeling can be promoted by angiotensin II (Ang II) in the renin-angiotensin system (RAS), leading to vascular dysfunction diseases such as hypertension and atherosclerosis. Researchers have recently focused on angiotensin I-converting enzyme inhibitory peptides (ACEIPs), that have desirable efficacy in vascular dysfunction therapy due to Ang II reduction by inhibiting ACE activity. Promising methods for the large-scale preparation of ACEIPs include selective enzymatic hydrolysis and microbial fermentation. Thus far, ACEIPs have been widely reported to be hydrolyzed from protein-rich sources, including animals, plants, and marine organisms, while many emerging microorganism-derived ACEIPs are theoretically biosynthesized through the nonribosomal peptide synthase (NRPS) pathway. Notably, vasodilatation, anti-inflammation, and vascular reconstruction reversal of ACEIPs are strongly correlated. However, the related molecular mechanisms underlying signal transduction regulation in vivo remain unclear. We provide a comprehensive update of the ACE-Ang II-G protein-coupled type 1 angiotensin receptor (AT1R) axis signaling and its functional significance for potential translation into therapeutic strategies, particularly targeting AT1R by ACEIPs, as well as specific related signaling pathways. Future studies are expected to verify the biosynthetic regulatory mechanism of ACEIPs via the NRPS pathway, the effect of gut microbiota metabolism on vascular dysfunction and rigorous studies of ACE-Ang II-AT1R signaling pathways mediated by ACEIPs in large animals and humans.

Rivaroxaban attenuates cardiac hypertrophy by inhibiting protease-activated receptor-2 signaling in renin-overexpressing hypertensive mice

Rivaroxaban (Riv), a direct factor Xa (FXa) inhibitor, exerts anti-inflammatory effects in addition to anticoagulation. However, its role in cardiovascular remodeling is largely unknown. We tested the hypothesis that Riv attenuates the progression of cardiac hypertrophy and fibrosis induced by continuous activation of the renin-angiotensin system (RAS) in renin-overexpressing hypertensive transgenic (Ren-Tg) mice. We treated 12-week-old male Ren-Tg and wild-type (WT) mice with a diet containing Riv (12 mg/kg/day) or a regular diet for 4 weeks. After this, FXa in plasma significantly increased in Ren-Tg mice compared with WT mice, and Riv inhibited this increase. Left ventricular wall thickness (LVWT) and the area of cardiac fibrosis evaluated by Masson's trichrome staining were greater in Ren-Tg mice than in WT mice, and Riv decreased them. Cardiac expression levels of the protease-activated receptor (PAR)-2, tumor necrosis factor-α, transforming growth factor (TGF)-β1, and collagen type 3 α1 (COL3A1) genes were all greater in Ren-Tg mice than in WT mice, and Riv attenuated these increases. To investigate the possible involvement of PAR-2, we treated Ren-Tg mice with a continuous subcutaneous infusion of 10 μg/kg/day of the PAR-2 antagonist FSLLRY for 4 weeks. FSLLRY significantly decreased LVWT and cardiac expression of PAR-2, TGF-β1, and COL3A1. In isolated cardiac fibroblasts (CFs), Riv or FSLLRY pretreatment inhibited the FXa-induced increase in the phosphorylation of extracellular signal-regulated kinases. In addition, Riv or FSLLRY inhibited FXa-stimulated wound closure in CFs. Riv exerts a protective effect against cardiac hypertrophy and fibrosis development induced by continuous activation of the RAS, partly by inhibiting PAR-2.

Activated Factor X Signaling Pathway via Protease-Activated Receptor 2 Is a Novel Therapeutic Target for Preventing Atrial Fibrillation

BACKGROUND

Activated factor X (FXa), which contributes to chronic inflammation via protease-activated receptor 2 (PAR2), might play an important role in atrial fibrillation (AF) arrhythmogenesis. This study aimed to assess whether PAR2 signaling contributes to AF arrhythmogenesis and whether rivaroxaban ameliorates atrial inflammation and prevents AF.

METHODS AND RESULTS

In Study 1, PAR2 deficient (PAR2-/-) and wild-type mice were infused with angiotensin II (Ang II) or a vehicle via an osmotic minipump for 2 weeks. In Study 2, spontaneously hypertensive rats (SHRs) were treated with rivaroxaban, warfarin, or vehicle for 2 weeks after 8 h of right atrial rapid pacing. The AF inducibility and atrial remodeling in both studies were examined. Ang II-treated PAR2-/- mice had a lower incidence of AF and less mRNA expression of collagen1 and collagen3 in the atrium compared to wild-type mice treated with Ang II. Rivaroxaban significantly reduced AF inducibility compared with warfarin or vehicle. In SHRs treated with a vehicle, rapid atrial pacing promoted gene expression of inflammatory and fibrosis-related biomarkers in the atrium. Rivaroxaban, but not warfarin, significantly reduced expression levels of these genes.

CONCLUSIONS

The FXa-PAR2 signaling pathway might contribute to AF arrhythmogenesis associated with atrial inflammation. A direct FXa inhibitor, rivaroxaban, could prevent atrial inflammation and reduce AF inducibility, probably by inhibiting the pro-inflammatory activation.

Japanese cedar pollen upregulates the effector functions of eosinophils

Background

Symptoms of rhinitis and asthma can be exacerbated during Japanese cedar pollen (JCP)-scattering season, even in subjects who are not sensitized to JCP, suggesting that innate immune responses may contribute to this process. We previously reported that house dust mite directly activates the effector functions of eosinophils. Similar mechanisms may play roles in the JCP-related aggravation of allergic diseases.

Objective

To investigate whether JCP or Cry j 1, a major allergen of JCP, can modify the effector functions of eosinophils.

Methods

Eosinophils isolated from the peripheral blood of healthy donors were stimulated with either JCP or Cry j 1, and their adhesion to human intercellular adhesion molecule-1 was measured using eosinophil peroxidase assays. The generation of eosinophil superoxide anion (O₂⁻) was measured based on the superoxide dismutase-inhibitable reduction of cytochrome C. Concentrations of eosinophil-derived neurotoxin in the cell media were measured by enzyme-linked immunosorbent assay as a marker of degranulation.

Results

Both JCP and Cry j 1 directly induced eosinophil adhesiveness, generation of O₂⁻, and release of eosinophil-derived neurotoxin. Both anti-αM and anti-β2 integrin antibodies blocked all of these eosinophil functions induced by JCP and Cry j 1. Similarly, PAR-2 antagonists also partially suppressed all of these effector functions induced by JCP and Cry j 1.

Conclusion

JCP and Cry j 1 directly activate the functions of eosinophils, and both αMβ2 integrin and partly PAR-2 are contributed to this activation. Therefore, JCP-induced eosinophil activation may play a role in the aggravation of allergic airway diseases in nonsensitized patients as well as in JCP-sensitized patients.

Novel Targets for Hypertension Drug Discovery

PURPOSE OF REVIEW

Despite the availability of various medications and prescribing combination therapies, uncontrolled blood pressure and resistance are observed in more than 40% of patients. The purpose of this review is to discuss emerging novel approaches for the treatment of hypertension and propose future research and clinical directions.

RECENT FINDINGS

Hypertension is a common disease of the cardiovascular system which may arise solely or as a comorbidity of other disorders. It is a crucial risk factor for cardiovascular diseases such as coronary artery disease, myocardial infarction, congestive heart failure, renal failure, and stroke. The results from current literature regarding the novel approaches showed several targets that could be explored as potential therapeutic options. These include toll-like receptor 4, a critical regulator of angiotensin II-induced hypertension; protease-activated receptor 2, which promotes collagen deposition and inflammatory responses; chemerin, which causes metabolic and obesity-associated hypertension; apelin receptor; transient receptor potential melastatin; urotensin-II; and Tie2 receptor. This review discusses various targets and pathways that could be emerging pharmacological therapies for hypertension.

Quantification of uncertainty in a new network model of pulmonary arterial adventitial fibroblast pro-fibrotic signalling

Here, we present a novel network model of the pulmonary arterial adventitial fibroblast (PAAF) that represents seven signalling pathways, confirmed to be important in pulmonary arterial fibrosis, as 92 reactions and 64 state variables. Without optimizing parameters, the model correctly predicted 80% of 39 results of input-output and inhibition experiments reported in 20 independent papers not used to formulate the original network. Parameter uncertainty quantification (UQ) showed that this measure of model accuracy is robust to changes in input weights and half-maximal activation levels (EC50), but is more affected by uncertainty in the Hill coefficient (n), which governs the biochemical cooperativity or steepness of the sigmoidal activation function of each state variable. Epistemic uncertainty in model structure, due to the reliance of some network components and interactions on experiments using non-PAAF cell types, suggested that this source of uncertainty had a smaller impact on model accuracy than the alternative of reducing the network to only those interactions reported in PAAFs. UQ highlighted model parameters that can be optimized to improve prediction accuracy and network modules where there is the greatest need for new experiments. This article is part of the theme issue 'Uncertainty quantification in cardiac and cardiovascular modelling and simulation'.

Exogenous Activation of Protease-Activated Receptor 2 Attenuates Cutaneous Vasodilatation and Sweating in Older Men Exercising in the Heat

BACKGROUND

Protease-activated receptor 2 (PAR2) exists in the cutaneous vasculature and eccrine sweat glands. We previously showed that in young habitually active men, exogenous PAR2 activation via the agonist SLIGKV-NH2 had no effect on heat loss responses of cutaneous vasodilatation and sweating during rest or exercise in the heat. However, ageing is associated with altered mechanisms governing these responses. Thus, the effect of exogenous PAR2 activation on cutaneous vasodilatation and sweating in older individuals may differ from that in young adults.

METHODS

Local cutaneous vascular conductance (CVC) and sweat rate were measured in 9 older males (62 ± 4 years) at four forearm skin sites treated with the following: (1) lactated Ringer solution (control), (2) 0.05 mM, (3) 0.5 mM, or (4) 5 mM SLIGKV-NH2. Measurements were performed while participants rested in a non-heat-stress environment (25°C) for ∼60 min and an additional 50 min thereafter in the heat (40°C). Participants then performed 50 min of cycling at a fixed metabolic heat load of 200 W/m2 (to maintain the same thermal drive for heat loss between participants) followed by a 30-min recovery.

RESULTS

CVC during non-heat-stress resting was elevated from the control site with 5 mM SLIGKV-NH2 (p ≤ 0.05), but this response was not observed during ambient heat exposure. By contrast, 5 mM SLIGKV-NH2 lowered CVC during the early stage (10 and 20 min) of exercise compared to the control site (all p ≤ 0.05). Although sweating during non-heat-stressed and heat-stressed resting was not affected by any dose of SLIGKV-NH2, it was reduced with all SLIGKV-NH2 doses relative to the control site during and following exercise (all p ≤ 0.05).

CONCLUSION

We show that while exogenous PAR2 activation induces cutaneous vasodilatation at rest under non-heat-stressed conditions, it attenuates cutaneous vasodilatation and sweating during and following an exercise-induced heat stress in older men.

Dermatophagoides farinae Upregulates the Effector Functions of Eosinophils through αMβ2-Integrin and Protease-Activated Receptor-2

BACKGROUND

Even in subjects who are not sensitized to house dust mite (HDM), allergic symptoms can be aggravated by exposure to dust, suggesting that innate immune responses may be involved in these processes. Since eosinophils express pattern recognition receptors, HDM may directly upregulate eosinophil functions through these re ceptors. The objective of this study was to examine whether Dermatophagoides farinae (Df), a representative HDM, or Der f 1, a major allergen of Df, modifies the effector functions of eosinophils.

METHODS

Eosinophils isolated from the blood of healthy donors or allergic patients were stimulated with Df extract or Der f 1, and their adhesion to recombinant human intercellular adhesion molecule (ICAM)-1 was measured using eosinophil peroxidase assays. Generation of the eosinophil superoxide anion (O2-) was examined based on the superoxide dismutase-inhibitable reduction of cytochrome C. Eosinophil-derived neurotoxin (EDN) concentrations in cell media were measured by ELISA as a marker of degranulation.

RESULTS

Df extract or Der f 1 directly induced eosinophil adhesion to ICAM-1, O2- generation, and EDN release. Anti-αM- or anti-β2-integrin antibodies or protease-activated receptor (PAR)-2 antagonists suppressed the eosinophil adhesion, O2- generation, and EDN release induced by Df extract or Der f 1. Eosinophils from allergic patients showed higher adhesion to ICAM-1 than those from healthy donors.

CONCLUSIONS

These findings suggested that Df extract and Der f 1 directly activate eosinophil functions through αMβ2-integrin and PAR-2. Eosinophil activation by HDM may play roles in the aggravation of allergic symptoms, not only in HDM-sensitized patients, but also in nonsensitized patients.

Factor Xa inhibition by rivaroxaban regulates fibrogenesis in human atrial fibroblasts with modulation of nitric oxide synthesis and calcium homeostasis

BACKGROUND

Rivaroxaban, a widely used factor Xa inhibitor in reducing stroke in atrial fibrillation (AF) patients has multiple biological effects with activation of protease-activated receptor (PAR) signaling. Atrial fibrosis plays a critical role in the pathophysiology of AF. In this study, we evaluated whether rivaroxaban regulates atrial fibroblast activity and its underlying mechanisms.

METHODS AND RESULTS

Migration, proliferation analyses, nitric oxide (NO) production assay, calcium fluorescence imaging, and western blots were conducted in human atrial fibroblasts with or without rivaroxaban (100 nmol/L or 300 nmol/L) and co-administration of L-NAME (L-NG-nitro arginine methyl ester, 100 μmol/L), EGTA (Ethylene glycol tetra-acetic acid, 1 mmol/L), thrombin (0.5 U/mL), PAR1 agonist peptide (TFLLR-NH2, 100 μmol/L), PAR1 inhibitor (SCH79797, 0.5 μmol/L) and PAR2 inhibitor (GB83, 10 μmol/L). Atrial fibrosis was examined in isoproterenol (100 mg/kg, subcutaneous injection)-treated rats with or without rivaroxaban (10 mg/kg/day orally for 14 consecutive days). Rivaroxaban reduced the migration, pro-collagen type I production, and proliferation of atrial fibroblasts. Rivaroxaban decreased phosphorylated endothelial NO synthase (eNOS) (Thr 495, an inhibitory phosphorylated site of eNOS), and calcium (Ca²⁺) entry, and increased NO production. Moreover, L-NAME blocked the effects of rivaroxaban on fibroblast collagen and NO production. In the presence of EGTA, the migratory capability was similarly decreased in atrial fibroblasts with and without treatment with rivaroxaban (100 nmol/L), which suggests that rivaroxaban decreases migratory capability of atrial fibroblasts by inhibiting Ca²⁺ entry. Additionally, rivaroxaban significantly attenuated the effects of thrombin, and TFLLR-NH2 on migratory, proliferative, and pro-collagen type I production capability in atrial fibroblasts. SCH79797 or GB83 decreased pro-collagen type I production, migration, and proliferation capability in fibroblasts, but combined SCH79797 or GB83 with and without rivaroxaban had similar fibroblast activity. Moreover, rivaroxaban significantly decreased atrial fibrosis in isoproterenol-treated rats.

CONCLUSIONS

Rivaroxaban (100-300 nmol/L) regulates atrial fibroblast activity and atrial fibrosis by increasing NO production and decreasing Ca²⁺ entry through inhibition of PAR signaling.

Signaling Crosstalk of TGF-β/ALK5 and PAR2/PAR1: A Complex Regulatory Network Controlling Fibrosis and Cancer

Both signaling by transforming growth factor-β (TGF-β) and agonists of the G Protein-coupled receptors proteinase-activated receptor-1 (PAR1) and -2 (PAR2) have been linked to tissue fibrosis and cancer. Intriguingly, TGF-β and PAR signaling either converge on the regulation of certain matrix genes overexpressed in these pathologies or display mutual regulation of their signaling components, which is mediated in part through sphingosine kinases and sphingosine-1-phosphate and indicative of an intimate signaling crosstalk between the two pathways. In the first part of this review, we summarize the various regulatory interactions that have been discovered so far according to the organ/tissue in which they were described. In the second part, we highlight the types of signaling crosstalk between TGF-β on the one hand and PAR2/PAR1 on the other hand. Both ligand–receptor systems interact at various levels and by several mechanisms including mutual regulation of ligand–ligand, ligand–receptor, and receptor–receptor at the transcriptional, post-transcriptional, and receptor transactivation levels. These mutual interactions between PAR2/PAR1 and TGF-β signaling components eventually result in feed-forward loops/vicious cycles of matrix deposition and malignant traits that exacerbate fibrosis and oncogenesis, respectively. Given the crucial role of PAR2 and PAR1 in controlling TGF-β receptor activation, signaling, TGF-β synthesis and bioactivation, combining PAR inhibitors with TGF-β blocking agents may turn out to be more efficient than targeting TGF-β alone in alleviating unwanted TGF-β-dependent responses but retaining the beneficial ones.

Endothelial Cells Inhibit the Angiotensin II Induced Phenotypic Modulation of Rat Vascular Adventitial Fibroblasts

The phenotypic modulation of vascular adventitial fibroblasts plays an important role in vascular remodeling. Evidence have shown that endothelial cells and adventitial fibroblasts interact under certain conditions. In this study, we investigated the influence of endothelial cells on the phenotypic modulation of adventitial fibroblasts. Endothelial cells and adventitial fibroblasts from rat thoracic aorta were cultivated in a co-culture system and adventitial fibroblasts were induced with angiotensin II (Ang II). Collagen I and alpha smooth muscle actin (α-SMA) expression and migration of adventitial fibroblasts were analyzed. Ang II upregulated the expression of collagen I and α-SMA and the migration of adventitial fibroblasts. Adventitial fibroblasts-endothelial cells co-culturing attenuated the effects of Ang II. Homocysteine-treated endothelial cells, which are functionally impaired, were less inhibitory of the phenotypic modulation of adventitial fibroblasts. Supplementation of endothelial cells with L-arginine (L-Arg) or 8-bromoguanosine 3',5'-cyclic monophosphate (8-BrcGMP) enhanced the trends, while with L-NG-nitroarginine methyl ester (L-NAME) or 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) the opposite effect was observed. Under the influence of Ang II, adventitial fibroblasts were prone to undergo phenotypic modulation, which was closely related to vascular remodeling. Our study showed that endothelial cells influenced fibroblast phenotypic transformation and such effect would be mediated through the nitric oxide (NO)/cGMP signaling pathway. J. Cell. Biochem. 118: 1921-1927, 2017. © 2017 Wiley Periodicals, Inc.