Role of angiotensin II and angiotensin type-1 receptor in scorpion venom-induced cardiac and aortic tissue inflammation

Protein and peptide profiles of rats' organs in scorpion envenomation

Problem of scorpion envenomation becomes more alarming each year. Main effects of scorpion venom are commonly believed to be related to its neurotoxic properties, yet severe symptoms may also be developed due to the uncontrolled enzymatic activity and formation of various bioactive molecules, including middle-mass molecules (MMMs). MMMs are considered as endogenous intoxication markers, their presence may indicate multiple organ failure. Scorpions, belong to the Leiurus macroctenus species, are very dangerous, nevertheless, effects of their venom on protein and peptide composition within the tissues remains unclear. In this work we have focused the attention on changes in protein and MMM levels and peptide composition in various organs during Leiurus macroctenus envenomation. The results revealed a decrease in protein level during envenomation as well as a significant increment of MMM₂₁₀ and MMM₂₅₄ levels in all assessed organs. Quantitative and qualitative compositions of various protein and peptide factions were continually changing. All of this may suggest that Leiurus macroctenus sting causes considerable destruction of cell microenvironment across all essential organs, providing systemic envenomation. In addition, MMM level increment may indicate endogenous intoxication development. Peptides, formed during envenomation, may possess various bioactive properties, analysis of which constitutes an area of further studies.

French Scorpionism (Mainland and Oversea Territories): Narrative Review of Scorpion Species, Scorpion Venom, and Envenoming Management

Sixty-seven scorpion species have been described in France and its territories, where they have been found to be heterogeneously distributed. Indeed, only one species can be found on Réunion Island, while 38 species exist in French Guiana. The number of stings is also heterogenous, with up to 90 stings per 100,000 inhabitants occurring annually. Scorpion species can frequently be determined through simple visual factors, including species of medical importance (i.e., Buthus, Centruroides and Tityus). Scorpion venom is composed of local enzymes and peptides with a cysteine-stabilized α/β motif (NaTxs, Ktxs, Calcines), which allow for venom diffusion and the prey's incapacitation, respectively. Harmful scorpion species are limited to Centruroides pococki in the French West Indies, which can induce severe envenoming, and the Tityus obscurus and Tityus silvestris in French Guiana, which can cause fatalities in children and can induce severe envenoming, respectively. Envenomation by one of these scorpions requires hospital monitoring as long as systemic symptoms persist. Typical management includes the use of a lidocaine patch, pain killers, and local antiseptic. In the case of heart failure, the use of dobutamine can improve survival, and pregnant women must consult an obstetrician because of the elevated risk of preterm birth or stillbirth. France does not have scorpion antivenom, as scorpion stings are generally not fatal.

An update on ACE2 amplification and its therapeutic potential

The renin angiotensin system (RAS) plays an important role in the pathogenesis of variety of diseases. Targeting the formation and action of angiotensin II (Ang II), the main RAS peptide, has been the key therapeutic target for last three decades. ACE‐related carboxypeptidase (ACE2), a monocarboxypeptidase that had been discovered 20 years ago, is one of the catalytically most potent enzymes known to degrade Ang II to Ang‐(1‐7), a peptide that is increasingly accepted to have organ‐protective properties that oppose and counterbalance those of Ang II. In addition to its role as a RAS enzyme ACE2 is the main receptor for SARS‐CoV‐2. In this review, we discuss various strategies that have been used to achieve amplification of ACE2 activity including the potential therapeutic potential of soluble recombinant ACE2 protein and novel shorter ACE2 variants.

Oxidative stress parameters in patients with ascending aortic dilatation

Background/aim

This study aimed to determine plasma thiol, disulphide, and serum ischemia-modified albumin (IMA) levels and ferroxidase activity in patients with ascending aorta dilatation (AAD) in comparison to those without AAD and to evaluate the predictive value of these oxidative stress parameters for AAD.

Materials and methods

This study was designed as a cross-sectional study of 184 patients who applied to our cardiology clinic. Our study population consisted of patients with AAD (n = 85) and without AAD (n = 99). A spectrophotometric method was used to determine plasma thiol, disulphide, and serum IMA levels and ferroxidase activity.

Results

The native thiol and the total thiol levels were significantly higher in the control group than the AAD group (P < 0.001), whereas the disulphide and IMA levels and the ferroxidase activity were similar between the groups. The native thiol and the total thiol levels were inversely and significantly correlated with ascending aortic diameter (r = –0.38, P < 0.001; r = –0.39, P < 0.001; respectively). The left ventricle mass and the total thiol levels were independent predictors of ascending aortic diameter (β= 0.223, P = 0.02; β= –0.340, P < 0.001; respectively).

Conclusion

Among oxidative stress parameters including thiols, disulphide, IMA, and ferroxidase activity, only the lower total thiol levels appear to confer a high risk for AAD development. Along with the proven diagnostic imaging methods, thiol levels may be helpful to diagnose and stratify patients with AAD.

Exploring the beneficial role of telmisartan in sepsis-induced myocardial injury through inhibition of high-mobility group box 1 and glycogen synthase kinase-3β/nuclear factor-κB pathway

In the present experimental study, cecal ligation and puncture significantly increased the myocardial injury assessed in terms of excess release of creative kinase-MB (CK-MB), cardiac troponin I (cTnI), interleukin (IL)-6 and decrease of IL-10 in the blood following 12 h of laparotomy procedure as compared to normal control. Also, a significant increase in protein expression levels of high-mobility group box 1 (HMGB1) and decreased phosphorylation of glycogen synthase kinase-3β (GSK-3β) was observed in the myocardial tissue as compared to normal control. A single independent administration of telmisartan (2 and 4 mg/kg) and AR-A014418 (1 and 2 mg/kg) substantially reduced sepsis-induced myocardial injury in terms of decrease levels of CK-MB, cTnI and IL-6, HMGB1, GSK-3β and increase in IL-10 and p-GSK-3β in the blood in sepsis- subjected rats. The effects of telmisartan at dose 4 mg/kg and AR-A014418 at a dose of 2 mg/kg were significantly higher than the telmisartan at a dose of 2 mg/kg and AR-A014418 1 mg/kg respectively. Further, no significant effects on different parameters were observed in the sham control group in comparison to normal. Therefore it is plausible to suggest that sepsis may increase the levels of angiotensin II to trigger GSK-3β-dependent signaling to activate the HMGB1/receptors for advanced glycation end products, which may promote inflammation and myocardial injury in sepsis-subjected rats.

Involvement of the Endothelin Receptor Type A in the Cardiovascular Inflammatory Response Following Scorpion Envenomation

Elevated levels of endothelin-1 (ET-1) were recorded in sera of scorpion sting patients. However, no studies focused on the mechanism of ET-1 involvement in the pathogenesis of scorpion envenomation, particularly in the cardiovascular system which is seriously affected in severe cases of scorpion stings. Inflammation induced by Androctonus australis hector (Aah) scorpion venom in the heart together with the aorta was studied in mice pretreated with a specific endothelin A receptor (ETA-R) inhibitor. ETA-R inhibition resulted in the attenuation of the high amounts of cytokine (tumor necrosis factor alpha (TNF-α) and interleukin-17 (IL-17)) recorded in the sera of envenomed mice. The recovery of the oxidative stress marker balance and matrix metalloproteinase (MMP) expression were also observed, concomitantly with the reduction of tissular neutrophil infiltration. Additionally, the cardiac and the aortic tissue alterations, and the metabolic enzymes (creatine kinase (CK) and muscle–brain isoform creatine kinase (CK-MB)) overspread into sera were significantly attenuated. Obtained results suggest the implication of endothelin throughout its ETA receptors in the inflammatory response observed in the cardiovascular components during scorpion envenomation. Further knowledge is needed to better understand the implication of the endothelin axis and to improve the therapeutic management of severe scorpion sting cases.

FNDC5 Attenuates Oxidative Stress and NLRP3 Inflammasome Activation in Vascular Smooth Muscle Cells via Activating the AMPK-SIRT1 Signal Pathway

Vascular oxidative stress and inflammation play a major role in vascular diseases. This study was aimed at determining the protective roles of fibronectin type III domain-containing 5 (FNDC5) in angiotensin II- (Ang II-) induced vascular oxidative stress and inflammation and underlying mechanisms. Wild-type (WT) and FNDC5^−/− mice, primary mouse vascular smooth muscle cells (VSMCs), and the rat aortic smooth muscle cell line (A7R5) were used in the present study. Subcutaneous infusion of Ang II caused more serious hypertension, vascular remodeling, oxidative stress, NLRP3 inflammasome activation, AMPK phosphorylation inhibition, and SIRT1 downregulation in the aorta of FNDC5^−/− mice than those of WT mice. Exogenous FNDC5 attenuated Ang II-induced superoxide generation, NADPH oxidase 2 (NOX2) and NLRP3 upregulation, mature caspase-1, and interleukin-1β (IL-1β) production in A7R5 cells. The protective roles of FNDC5 were prevented by SIRT-1 inhibitor EX527, AMPK inhibitor compound C, or integrin receptor inhibitor GLPG0187. FNDC5 attenuated the Ang II-induced inhibition in SIRT1 activity, SIRT1 protein expression, and AMPKα phosphorylation in A7R5 cells, which were prevented by compound C, EX527, and GLPG0187. FNDC5 deficiency deteriorated Ang II-induced oxidative stress, NLRP3 inflammasome activation, AMPK phosphorylation inhibition, and SIRT1 downregulation in primary aortic VSMCs of mice, which were prevented by exogenous FNDC5. These results indicate that FNDC5 deficiency aggravates while exogenous FNDC5 alleviates the Ang II-induced vascular oxidative stress and NLRP3 inflammasome activation via the AMPK-SIRT1 signal pathway in VSMCs.

MiR155-5p Inhibits Cell Migration and Oxidative Stress in Vascular Smooth Muscle Cells of Spontaneously Hypertensive Rats

Migration of vascular smooth muscle cells (VSMCs) is essential for vascular reconstruction in hypertension and several vascular diseases. Our recent study showed that extracellular vesicles derived from vascular adventitial fibroblasts of normal rats inhibited VSMC proliferation by delivering miR155-5p to VSMCs. It is unknown whether miR155-5p inhibits cell migration and oxidative stress in VSMCs of spontaneously hypertensive rats (SHR) and in angiotensin II (Ang II)-treated VSMCs. The purpose of this study was to determine the role of miR155-5p in VSMC migration and its underlying mechanisms. Primary VSMCs were isolated from the aortic media of Wistar-Kyoto rats (WKY) and SHR. Wound healing assay and Boyden chamber assay were used to evaluate VSMC migration. A miR155-5p mimic inhibited, and a miR155-5p inhibitor promoted the migration of VSMC of SHR but had no significant effect on the migration of VSMC of WKY. The miR155-5p mimic inhibited angiotensin-converting enzyme (ACE) mRNA and protein expression in VSMCs. It also reduced superoxide anion production, NAD(P)H oxidase (NOX) activity, as well as NOX2, interleukin-1β (IL-1β), and tumor necrosis factor α (TNF-α) expression levels in VSMCs of SHR but not in VSMCs of WKY rats. Overexpression of miR155-5p inhibited VSMC migration and superoxide anion and IL-1β production in VSMCs of SHR but had no impact on exogenous Ang II-induced VSMC migration and on superoxide anion and IL-1β production in WKY rats and SHR. These results indicate that miR155-5p inhibits VSMC migration in SHR by suppressing ACE expression and its downstream production of Ang II, superoxide anion, and inflammatory factors. However, miR155-5p had no effects on exogenous Ang II-induced VSMC migration.

Relationships Between the Cardio-Ankle Vascular Index and Pulsatility Index of the Common Carotid Artery in Patients With Cardiovascular Risk Factors

Background

Pulsatility index (PI) is a hemodynamic parameter determined using Doppler sonography; it reflects the degree of peripheral vascular resistance. Moreover, researchers have reported significant relationships between an increase in the PI of the common carotid artery (CCA) and ischemic stroke. This cross-sectional study aimed to clarify the relationships between cardio-ankle vascular index (CAVI) as a marker of arterial stiffness and the PI of the CCA in patients with cardiovascular risk factors for the primary prevention of ischemic stroke.

Methods

A total of 405 outpatients undergoing treatment for cardiovascular risk factors (152 men and 253 women; mean age ± standard deviation, 64 ± 9 years) with no history of cardiovascular events, including ischemic stroke, were enrolled. The CAVI and the PI of the CCA were measured using commercial devices, and their relationships to various clinical parameters were examined.

Results

A significant positive correlation was observed between the CAVI and the PI of the CCA (r = 0.44, P < 0.001). Further, multiple regression analysis revealed that the CAVI (β = 0.19, P < 0.001) was selected as independent factor for PI of the CCA as a subordinate factor. Meanwhile, high-sensitivity C-reactive protein, as an inflammation marker, and skin autofluorescence, as a marker of advanced glycation end products in the tissues, were selected as independent variables for either the CAVI or the PI of the CCA as a subordinate factor. The receiver-operating characteristic curve analysis indicated that the cut-off point of the CAVI for high PI of the CCA (> 1.60) as a risk value of stroke incidence by previous report was 9.1 (area under the curve = 0.750, P < 0.001).

Conclusion

The present results indicate that the CAVI reflects cerebrovascular resistance in patients with cardiovascular risk factors. Moreover, the risk value of the CAVI for ischemic stroke incidence was considered to be 9.1 in these patients.

Renin-angiotensin system activation and imbalance of matrix metalloproteinase-9/tissue inhibitor of matrix metalloproteinase-1 in cold-induced stroke

AIMS

In the present study, we investigated the roles of renin-angiotensin system (RAS) activation and imbalance of matrix metalloproteinase-9 (MMP-9)/tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) in cold-induced stroke during chronic hypertension, as well as the protective effects of captopril and recombinant human TIMP-1 (rhTIMP-1).

MAIN METHODS

Rats were randomly assigned to sham; 2-kidney, 2-clip (2K-2C); 2K-2C + captopril, and 2K-2C + rhTIMP-1 groups. After blood pressure values had stabilized, each group was randomly divided into an acute cold exposure (ACE) group (12-h light at 22 °C/12-h dark at 4 °C) and a non-acute cold exposure (NACE) group (12-h light/12-h dark at 22 °C), each of which underwent three cycles of exposure. Captopril treatment was administered via gavage (50 mg/kg/d), while rhTIMP-1 treatment was administered via the tail vein (60 μg/kg/36 h).

KEY FINDINGS

In the 2K-2C group, angiotensin II (AngII) and MMP-9 levels increased in both the plasma and cortex, while no such changes in TIMP-1 expression were observed. Cold exposure further upregulated AngII and MMP-9 levels and increased stroke incidence. Captopril and rhTIMP-1 treatment inhibited MMP-9 expression and activation and decreased stroke incidence in response to cold exposure.

SIGNIFICANCE

The present study is the first to demonstrate that cold exposure exacerbates imbalance between MMP-9 and TIMP-1 by activating the RAS, which may be critical in the initiation of stroke during chronic hypertension. In addition, our results suggest that captopril and rhTIMP-1 exert protective effects against cold-induced stroke by ameliorating MMP-9/TIMP-1 imbalance.

Candesartan inhibits inflammation through an angiotensin II type 1 receptor independent way in human embryonic kidney epithelial cells

Besides stimulating vasoconstriction, Angiotensin II is also well known in inducing reactive oxygen species and promoting inflammatory phenotype switch via its type 1 receptor. In clinic, Angiotensin II type 1 (AT1) receptor blocker like candesartan has been widely applied as an antihypertensive medication. We previous have demonstrated that a higher dose of candesartan plays a protective role after kidney injury. However, whether candesartan could exhibit anti-inflammatory effects remains unclear. Here, by stimulating isolated human embryonic kidney epithelial cells with tumor necrosis factor-α (TNF-α), we observed the anti-inflammation capacity of candesartan ex vivo. It was found that pre-treat with candesartan significantly suppressed transforming growth factor-β (TGF-β) and interleukin-6 (IL-6) expression after incubation with TNF-α. Surprisingly, silence of angiotensin II type 1 receptor has little effects on reducing TGF-β or IL-6 products. Furthermore, candesartan inhibited TNF-α-induced oxidative stress in the primary cultured tubular epithelial cells. Overall, our data indicates that candesartan suppresses TNF-α-induced inflammatory cytokine production by inhibiting oxidative stress, rather than block AT1 receptor activity.

Serotherapy against Voltage-Gated Sodium Channel-Targeting αToxins from Androctonus Scorpion Venom

Because of their venom lethality towards mammals, scorpions of the Androctonus genus are considered a critical threat to human health in North Africa. Several decades of exploration have led to a comprehensive inventory of their venom components at chemical, pharmacological, and immunological levels. Typically, these venoms contain selective and high affinity ligands for the voltage-gated sodium (Na_v) and potassium (K_v) channels that dictate cellular excitability. In the well-studied Androctonus australis and Androctonus mauretanicus venoms, almost all the lethality in mammals is due to the so-called α-toxins. These peptides commonly delay the fast inactivation process of Na_v channels, which leads to increased sodium entry and a subsequent cell membrane depolarization. Markedly, their neutralization by specific antisera has been shown to completely inhibit the venom’s lethal activity, because they are not only the most abundant venom peptide but also the most fatal. However, the structural and antigenic polymorphisms in the α-toxin family pose challenges to the design of efficient serotherapies. In this review, we discuss past and present accomplishments to improve serotherapy against Androctonus scorpion stings.

Cerebrospinal inflammatory response following scorpion envenomation: role of histamine H1 and H3 receptors

BACKGROUND

The mechanism of the inflammatory process induced by scorpion venom in the cerebrospinal tissues has not yet been completely elucidated. Therefore, we aimed to investigate the role of histamine through its H1 and H3 receptors in this process.

METHODS

Histamine H1 and H3 receptor antagonists, Hydroxyzine (10 mg/kg) and Betaserc (20 mg/kg), respectively, were administered by intraperitoneal route to mice 1 h before subcutaneous envenomation with a subletal dose (0.5 mg/kg) of Androctonus australis hector venom. Cerebrospinal inflammation response was assessed 24 h after envenomation by evaluating the vascular permeability changes, inflammatory cell infiltration, oxidative/nitrosative stress marker levels (hydrogen peroxide, nitric oxide, malondialdehyde, glutathione and catalase) and by histological examination of cerebrospinal tissue.

RESULTS

Envenomed mice displayed an installation of an inflammatory response marked by increased vascular permeability (76% and 68% in brain and spinal cord, respectively, in comparison to controls), inflammatory cell infiltration, increased pro-oxidant levels and decreased anti-oxidant markers (p  < 0.05 to p  < 0.001). Scorpion venom also induced structural changes in brain and spinal cord tissues. Hydroxyzine seemed to be more efficient than Betaserc in the prevention of the induced cerebrospinal inflammation response, as evidenced by the decreased vascular permeability, inflammatory cell infiltration, pro-oxidant levels, increased anti-oxidant defense (p  < 0.05 to p  < 0.001) and a reduction of the anatomo-pathological alterations.

CONCLUSION

The results showed that the histamine H1 receptor is more involved in the induced central nervous system inflammatory response during scorpion envenomation.

The probable roles of valsartan in alleviating chronic obstructive pulmonary disease following co-exposure to cold stress and fine particulate matter

Angiotensin II (ANG II) might play an important role in the co-effects of cold stress and fine particulate matter (PM_2.5) on chronic obstructive pulmonary disease (COPD). The purpose of this study is to evaluate the roles of valsartan in alleviating COPD following co-exposure to cold stress and PM_2.5. Both the two intervention factors are carried out upon COPD rats with the intervention of valsartan. Blockade of angiotensin receptor by valsartan decreases the levels of malondialdehyde in the normal temperature and tumor necrosis factor-α under cold stress significantly. When treated with valsartan and PM_2.5 simultaneously, the expression of 8-hydroxy-2-deoxyguanosine, nuclear factor kappa B and heme oxygenase-1 decrease significantly in the group of cold stress. In conclusion, these results indicate that valsartan might relieve the co-effects of cold stress and PM_2.5 on COPD rat lung to some degree.

Thiol/disulphide homeostasis in thoracic aortic aneurysm and acute aortic syndrome

AIM

The aim of this study was to evaluate whether ranging values of thiol and disulphide herald a dilatation or impending acute aortic syndrome at thoracic aorta. Results/methodology: Study population consisted of patients with aortic aneurysm (n = 58), with acute aortic syndrome (n = 32) and without aortic aneurysm (control group; n = 61). A spectrophotometric method was used to determine thiol and disulphide. Native and total thiol levels were moderately correlated with maximal aortic diameter. At the end of 6 months, there was statistically significant increase in native, total thiol levels and decrease in disulfide and disulphide/native thiol ratio in operated group.

DISCUSSION/CONCLUSION

Lower thiol levels may be associated with the higher risk of aortic aneurysm development and may increase after surgical therapy.

Early intervention by Captopril does not improve wound healing of partial thickness burn wounds in a rat model

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Inhibition of the Renin Angiotensin System does not influence the inflammatory reaction in the burn wounds.

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Inhibition of the Renin Angiotensin System early during burn wound healing does not improve the process.

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Inhibition of the Renin Angiotensin System early during burn wound healing does not reduce scar formation.

The Renin Angiotensin System is involved in fibrotic pathologies in various organs such as heart, kidney and liver. Inhibition of this system by angiotensin converting enzyme antagonists, such as Captopril, has been shown beneficial effects on these pathologies. Captopril reduced the inflammatory reaction but also directly influenced the fibrotic process.

Prolonged and excessive inflammatory response is a major cause of hypertrophic scar formation in burns. We therefore evaluated the effect of Captopril on the healing of partial thickness burn wounds in a rat model.

Partial thickness contact burns were inflicted on the dorsum of the rats. The rats received either systemic or local treatment with Captopril. The inflammatory reaction and wound healing (scar) parameters were investigated and compared to control animals.

In this study we could not detect positive effects of either administration route with Captopril on the inflammatory reaction, nor on wound healing parameters. The local treatment showed reduced wound closure in comparison to the systemic treatment and the control group.

Early Captopril treatment of burn wounds did not show the beneficial effects that were reported for fibrotic disorders in other tissues. To influence the fibrotic response Captopril treatment at a later time point, e.g. during the remodeling phase, might still have beneficial effects.

Cyclooxygenase-2 Inhibition Limits Angiotensin II-Induced DNA Oxidation and Protein Nitration in Humans

Compared to other cyclooxygenase-2 inhibitors, celecoxib is associated with a lower cardiovascular risk, though the mechanism remains unclear. Angiotensin II is an important mediator of oxidative stress in the pathophysiology of vascular disease. Cyclooxygenase-2 may modify the effects of angiotensin II though this has never been studied in humans. The purpose of the study was to test the effects of selective cyclooxygenase-2 inhibition on plasma measures of oxidative stress, the vasoconstrictor endothelin-1, and nitric oxide metabolites, both at baseline and in respose to Angiotensin II challenge in healthy humans. Measures of 8-hydroxydeoxyguanosine, advanced oxidation protein products, nitrotyrosine, endothelin-1, and nitric oxide metabolites were assessed from plasma samples drawn at baseline and in response to graded angiotensin II infusion (3 ng/kg/min × 30 min, 6 ng/kg/min × 30 min) before and after 14 days of cyclooxygenase-2 inhibition in 14 healthy subjects (eight male, six female) in high salt balance, a state of maximal renin angiotensin system suppression. Angiotensin II infusion significantly increased plasma oxidative stress compared to baseline (8-hydroxydeoxyguanosine; +17%; advanced oxidation protein products; +16%), nitrotyrosine (+76%). Furthermore, levels of endothelin-1 levels were significantly increased (+115%) and nitric oxide metabolites were significantly decreased (−20%). Cycloxygenase-2 inhibition significantly limited the increase in 8-hydroxydeoxyguanosine, nitrotyrosine and the decrease in nitric oxide metabolites induced by angiotensin II infusion, though no changes in advanced oxidation protein products and endothelin-1 concentrations were observed. Cyclooxygenase-2 inhibition with celecoxib partially limited the angiotensin II-mediated increases in markers of oxidative stress in humans, offering a potential physiological pathway for the improved cardiovascular risk profile of this drug.