scholarly journals Hypothesis: Free SARS-CoV-2 spike protein S1 particles may act as a factor of COVID-19 pathogenesis.

2020 ◽  
Author(s):  
Andrey Letarov ◽  
Vladislav Babenko
Keyword(s):  
Angiotensin Ii ◽  
Murine Model ◽  
Renin Angiotensin System ◽  
Spike Protein ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Pulmonary Damage ◽  
Infected Cells ◽  
Ace Activity

The disbalance of the renin-angiotensin system was suggested to play an important role in the pathogenesis of the COVID-19 disease. Previously it has been shown that ACE2 expression in downregulated in the murine model in response to SARS-CoV infection and may be also induced by the recombinant spike protein alone. We hypothesize that the soluble SARS-CoV-2 spike protein S1 subunits shed from the infected cells and from the virions in vivo may bind to the ACE2 receptor and trigger ACE2 downregulation. Decreased ACE2 activity on the background of the constant or increased ACE activity in the lungs may lead to the prevalence of angiotensin II effects over angiotensin(1-7) connected to increased thrombosis, inflammation and pulmonary damage.

Androgens augment proximal tubule transport

2004 ◽  
Vol 287 (3) ◽  
pp. F452-F459 ◽  
Author(s):  
Albert Quan ◽  
Sumana Chakravarty ◽  
Jian-Kang Chen ◽  
Jian-Chun Chen ◽  
Samer Loleh ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Proximal Tubule ◽  
Specific Binding ◽  
Extracellular Volume ◽  
Renin Angiotensin System ◽  
Angiotensin Receptors ◽  
Sprague Dawley ◽  
Angiotensin System ◽  
Renin Angiotensin

The proximal tubule contains an autonomous renin-angiotensin system that regulates transport independently of circulating angiotensin II. Androgens are known to increase expression of angiotensinogen, but the effect of androgens on proximal tubule transport is unknown. In this in vivo microperfusion study, we examined the effect of androgens on proximal tubule transport. The volume reabsorptive rate in Sprague-Dawley rats given dihydrotestosterone (DHT) injections was significantly higher than in control rats given vehicle injections (4.57 ± 0.31 vs. 3.31 ± 0.23 nl·min−1·mm−1, P < 0.01). Luminally perfusing with either enalaprilat (10−4 M) to inhibit production of angiotensin II or losartan (10−8 M) to block the angiotensin receptor decreased the proximal tubule volume reabsorptive rate in DHT-treated rats to a significantly greater degree than in control vehicle-injected rats. The renal expression of angiotensinogen was shown to be higher in the DHT-treated animals, using Northern blot analysis. The expression of angiotensin receptors, determined by specific binding of angiotensin II, was not different in the two groups of animals. Brush-border membrane protein abundance of the Na/H exchanger, a membrane transport protein under angiotensin II regulation, was also higher in DHT-treated rats vs. control rats. Rats that received DHT had higher blood pressures than the control rats but had no change in their glomerular filtration rate. In addition, serum angiotensin II levels were lower in DHT-treated vs. control rats. These results suggest that androgens may directly upregulate the proximal tubule renin-angiotensin system, increase the volume reabsorptive rate, and thereby increase extracellular volume and blood pressure and secondarily decrease serum angiotensin II levels.

Effects of Tokishakuyakusan, Keishibukuryogan, Shakuyakukanzoto and Unkeito on Ovarian Endothelin, Renin and Angiotensin II in Pregnant Mare's Serum Gonadotropin-treated Immature Rats

1992 ◽  
Vol 20 (02) ◽  
pp. 175-179 ◽  
Author(s):  
Satoshi Usuki ◽  
Yoshie Usuki ◽  
Junko Tanaka ◽  
Yuko Kawakura
Keyword(s):  
Angiotensin Ii ◽  
Herbal Medicines ◽  
Renin Angiotensin System ◽  
Concomitant Treatment ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Immature Rats ◽  
Serum Gonadotropin ◽  
Peptide System

We have previously proposed the ovarian ERAANPS (endothelin-renin-angiotensin-atrial natriuretic peptide system). The present study was undertaken to examine in vivo the effects of herbal medicines [Tokishakuyakusan (TS), Keishibukuryogan (KB), Shakuyakukanzoto (SK) and Unkeito (UT)] on endothelin-l (ET), renin and angiotensin II (A II) in the ovaries, of immature rats treated with 10 IU PMS for 48 h. ET and all components of renin-angiotensin system (RAS) were found at high levels in the ovary. Concomitant treatment with PMS plus TS, KB, SK or UT, especially TS and UT, tended to decrease the ET levels in ovary, while components of RAS tended to increase. However, ET, renin and A II levels in plasma were not at all affected after treatment with TS, KB, SK or UT. These results suggest that TS, KB, SK or UT may regulate the ovarian ERAANPS.

Effects of angiotensin II, ACTH, and KCl on the adrenal renin-angiotensin system in the rat

1990 ◽  
Vol 122 (3) ◽  
pp. 369-373 ◽  
Author(s):  
Hiroyuki Sasamura ◽  
Hiromichi Suzuki ◽  
Ryuichi Kato ◽  
Takao Saruta
Keyword(s):  
Angiotensin Ii ◽  
Statistical Significance ◽  
Renin Angiotensin System ◽  
Plasma Aldosterone ◽  
Aldosterone Secretion ◽  
Plasma Aldosterone Concentration ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Captopril Treatment

Abstract Angiotensin II, ACTH and potassium chloride were administered to rats for 6 days and the effects on adrenal renin-like activity and adrenal angiotensin II/III immunoreactivity were investigated. Rats infused with angiotensin II(140 pmol/min) either ip or sc showed increases in adrenal angiotensin II/III immunoreactivity (p<0.05) and plasma aldosterone concentration (p<0.05), but no change in adrenal renin-like activity. Captopril treatment of angiotensin Il-infused rats caused a slight decrease in angiotensin II/III immunoreactivity which did not reach statistical significance. In contrast, rats treated with ACTH (Cortrosyn-Z, 3 IU/day, sc) showed an increase in adrenal renin-like activity (p<0.01), but no significant change in adrenal angiotensin II/III immunoreactivity. Rats treated with KCl in drinking water showed increases (p<0.05) in adrenal renin-like activity, adrenal angiotensin II/III immunoreactivity, and plasma aldosterone. These results suggest that angiotensin II, ACTH and potassium, three major regulators of aldosterone secretion by the adrenal gland, have different effects on the adrenal renin-angiotensin system when administered in vivo.

scholarly journals Persistent and selective upregulation of renin–angiotensin system in circulating T lymphocytes in unstable angina

2017 ◽  
Vol 18 (1) ◽  
pp. 147032031769884 ◽  
Author(s):  
Mirella Coppo ◽  
Manuela Bandinelli ◽  
Marco Chiostri ◽  
Loredana Poggesi ◽  
Maria Boddi
Keyword(s):  
T Cells ◽  
T Cell ◽  
Angiotensin Ii ◽  
T Lymphocytes ◽  
Unstable Angina ◽  
Stable Angina ◽  
Renin Angiotensin System ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Ace Activity

Introduction: Unstable angina is associated with an acute systemic inflammatory reaction and circulating T lymphocytes are activated. We investigated whether in unstable angina with marked immune system activation a selective upregulation of the circulating T-cell renin–angiotensin system, modulated by angiotensin II, could occur. Methods: We studied 13 unstable angina patients, 10 patients with stable angina and 10 healthy subjects. After T-lymphocyte isolation, mRNAs for angiotensin-converting enzyme (ACE) and angiotensin type 1 receptor (AT1-R) were quantified at baseline and after angiotensin II stimulation. ACE activity in cell pellet and supernatant and angiotensin II cell content were measured. Results: Plasma renin activity was similar in controls, stable and unstable angina patients. At baseline ACE and AT1-R mRNA levels were higher ( P<0.05) in T cells from unstable angina patients than in T cells from stable angina patients and controls, and further increased after angiotensin II addition to cultured T cells. ACE activity of unstable angina T cells was significantly higher than that of T cells from controls and stable angina patients. Only in T cells from unstable angina patients did angiotensin II stimulation cause the almost complete release of ACE activity in the supernatant. Conclusions: The circulating T-cell-based renin–angiotensin system from unstable angina patients was selectively upregulated. In vivo unstable angina T cells could locally increase angiotensin II concentration in tissues where they migrate independently of the circulating renin–angiotensin system.

scholarly journals Mouse glomerular epithelial cells in culture with features of podocytes in vivo express aminopeptidase A and angiotensinogen but not other components of the renin-angiotensin system.

1997 ◽  
Vol 8 (5) ◽  
pp. 706-719
Author(s):  
S Mentzel ◽  
J P Van Son ◽  
A S De Jong ◽  
H B Dijkman ◽  
R A Koene ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Monoclonal Antibodies ◽  
Angiotensin Ii ◽  
Epithelial Cells ◽  
Mrna Expression ◽  
Renin Angiotensin System ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Aminopeptidase A

The binding of antibodies to podocytic antigens such as the Heymann antigen or aminopeptidase A may lead to the induction of a membranous glomerulonephritis in several species. To study the possible future interactions of antibodies with antigens on these podocytes, epithelial cells from isolated mouse glomeruli were cultured. By indirect immunofluorescence, the cells were positive for cytokeratin, vimentin, desmin, and the ZO-1 protein, a component of the tight junction complex. When rat monoclonal antibodies were used, the cells were also positive for the hydrolases aminopeptidase A and dipeptidyl peptidase IV, and they stained with ASD-33, a monoclonal antibody that recognized an epitope only present on the cell membranes of mouse podocytes. They were negative for the von Willebrand factor and did not stain with a monoclonal antibody (ASD-13) that binds to endothelial cells of glomeruli and peritubular capillaries. By electron microscopy, the cells showed tight junctions but lacked Weibel Palade bodies (endothelium), desmosomes, and cilia (parietal epithelium). The mRNA expression of several components of the renin-angiotensin system was also examined, and some factors indirectly coupled to the renin-angiotensin system component angiotensin II in this podocytic culture by RT-PCR analysis. mRNA Expression for the angiotensin II degrading hydrolase aminopeptidase A and angiotensinogen was found, but this was not found for any other component of this system, such as renin, angiotensin-converting enzyme, or the angiotensin II receptors AT1a, AT1b, and AT2. Low mRNA expression for dipeptidyl peptidase IV was observed. In addition, expression of the growth factors transforming growth factor-beta and interleukin-7, and the extracellular matrix components fibronectin, laminin B2, perlecan, and collagen IV alpha 1, was observed. Given these characteristics, a glomerular epithelial cell culture with features of podocytes in vivo that will allow future studies on the interaction of anti-aminopeptidase A monoclonal antibodies and angiotensin II with aminopeptidase A was established. This is of interest in light of the observation that injection of mice with anti-aminopeptidase A antibodies causes an acute albuminuria.

Vasoactive intestinal peptide down-regulates the intrahepatic renin–angiotensin system in the anaesthetized rat

2000 ◽  
Vol 99 (3) ◽  
pp. 201-206
Author(s):  
V. Z. C. YE ◽  
K. A. DUGGAN
Keyword(s):  
Angiotensin Ii ◽  
Vasoactive Intestinal Peptide ◽  
Renin Angiotensin System ◽  
Plasma Renin ◽  
Sprague Dawley ◽  
Angiotensin I ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Sodium Loading ◽  
Ace Activity

Gastric sodium loading results in an increase in the portal venous concentration of vasoactive intestinal peptide (VIP) and down-regulation of both the intrahepatic and circulating renin–angiotensin systems. In the present study we sought to determine whether an increase in the concentration of VIP in the portal circulation might act to down-regulate the intrahepatic and/or circulating renin–angiotensin systems. Male Sprague–Dawley rats were infused intraportally with haemaccel vehicle or VIP in haemaccel for 60 min. Livers were harvested and blood was sampled. Angiotensin-converting enzyme (ACE) activity and angiotensinogen, angiotensin I, angiotensin II and renin concentrations were measured. VIP infusion decreased hepatic ACE activity (P < 0.05), the hepatic angiotensinogen concentration (P < 0.001) and the hepatic angiotensin I concentration (P < 0.05). The plasma angiotensinogen concentration and serum ACE activity were also decreased by intraportal VIP infusion (P < 0.05 for each). Plasma renin, angiotensin I and angiotensin II concentrations were unchanged by VIP infusion. We conclude that an increase in the portal venous VIP concentration down-regulates the intrahepatic renin–angiotensin system. These changes are similar to those reported after gastric sodium loading, and we suggest, therefore, that the increase in portal venous VIP that occurs after gastric sodium is the means by which the gastric sodium sensor signals the liver to effect these changes in the renin–angiotensin system.

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