Estrogen modulates the differential expression of cardiac myocyte chymase isoforms and diastolic function

Abstract

Background and objective Cardiac angiotensin II (Ang II) is involved in the diastolic dysfunction in postmenopausal women. Chymases, a family of serine proteases with chymotryptic activity, play a significant role in cardiac Ang II formation from its substrate Ang‐(1–12) in both human and rodent models. While human tissue expresses only the α‐form of chymase, α‐ and β‐forms exist in rodents. Five of the ten rat mast cell proteases (rMCP‐1–5) display chymase activity, and rats express predominantly the β‐chymase isoforms. This study was designed to assess the differences in enzymatic activity among these rMCP isoforms in Ang II formation, particularly in the cardiomyocyte (CM), and the effects of estrogen status on MCP gene expression and activities in female rat models. Methods and results Using conventional polymerase chain reaction (PCR) (Fig. 1A), real‐time PCR (Fig. 1B) and DNA sequencing (Fig. 1C), we demonstrated that MCP‐1, MCP‐2, MCP‐4, and MCP‐5 mRNAs are expressed in the CM of both spontaneously hypertensive rats (SHR) and normotensive Wistar‐Kyoto rats (WKY). While rMCP‐1 and rMCP‐5 gene transcripts were higher than other isoforms in both rat strains, WKY CM exhibits higher levels of rMCP‐1 and rMCP‐5 mRNAs compared to the SHR CM (Fig. 2). Ovariectomy (OVX) increased the expression of rMCP‐1 and rMCP‐5 mRNAs in WKY. In SHR, OVX was associated with a blunted increase in rMCP‐1 mRNA compared to OVX normotensive WKY. Chymase activity, measured by HPLC as Ang II formation from Ang‐(1–12), significantly correlated with rMCP‐1 and rMCP‐5 mRNA expression in both rat strains. Both rMCP‐1 and rMCP‐5 mRNA expressions were positively correlated with progressive diastolic dysfunction (increasing the ratio of early mitral inflow velocity‐to‐early mitral annular velocity, E/e′) and increases in left ventricular internal diameter end diastole. Conclusion These data show rMCP‐1 and rMCP‐5 as the Ang II forming chymase isoforms participating in diastolic dysfunction due to ovariectomy in rodents. Support or Funding Information This work was funded by grants from the National Heart Lung and Blood Institute (CMF and LG) P01‐HL051952 and the National Institute on Aging (LG) AG033727 of the National Institute of Health. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Activation of the Human Angiotensin-(1-12)-Chymase Pathway in Rats With Human Angiotensinogen Gene Transcripts

“…Given our previous findings documenting chymase as the primary Ang II-forming enzyme from Ang-(1-12) (20), we further assayed whether blockade of the type 1 Ang II receptors altered the expression of chymase gene transcripts in TGR(hAGT)L1623 rats. In agreement with the profile found in SHR and WKY rats (19), mast cell proteases (MCP-1 and MCP-5 showed equivalent expression in the heart of TGR(hAGT)L1623 rats (MCP-1: 0.928 ± 0.070 mRNA/GAPDH; MCP-5: 0.910 ± 0.058 mRNA/GAPDH; p > 0.05). Treatment with vehicle or valsartan did not change the expression of these gene transcripts.…”

“…Ang-(1-12) processing into biologically active peptides is mediated by ACE in the circulation (44) and chymase in cardiac and renal tissues (10, 20, 45). Corresponding to the heightened gene expression levels of MCP-1 and MCP-5, but not the other MCPs, in hearts of hypertensive and normotensive female rats (19), we show that these two cardiac chymase isoforms are also expressed in the heart of TGR(hAGT)L1623 rats. In keeping with previous studies, chymase has been visualized in human (46), dog (47, 48), and enlarged rat myocytes from volume overload due to an aorto-caval fistula (21, 49).…”

“…Total RNA was isolated from the heart using the RNeasy Lipit Tissue Mini Kit (Qiagen, Inc., Germantown, MD) and further purified using RNeasy MinElute Cleanup Kit (Qiagen, Inc., Germantown, MD) followed by quality assessment on an Agilent 2100 bioanalyzer, as described previously (18, 19). Relative quantification of mRNA levels by real-time qPCR for ACE, angiotensin converting enzyme 2 (ACE2), mast cell proteases (MCP-1, and MCP-5) was performed using a SYBR Green PCR kit (Qiagen, Inc., Germantown, MD) (19). Amplification and detection were performed with the QuantStudio 3 real-time PCR Systems (Applied Biosystems, Foster City, CA).…”

COVID-19 pandemic – Impact on elderly and is there a gender bias?

“…Estrogen is known to act as an anti-inflammatory in its effect on cardiovascular and bone health. [ 12 ] Takahashi et al . summarized that critical differences exist in the baseline immune capabilities in men and women during the early phase of SARS-COV-2 infection.…”

Is Sex a Determinant of COVID-19 Infection? Truth or Myth?

“…Based on the growing evidence suggesting a sex-based difference in COVID-19 outcomes, an assessment of sex-specific hormone activity, particularly estrogen, in COVID-19 pathogenesis is warranted. Estrogen is known to modulate CVD risk and we [ 11 ] and others [ 18 ] have established a role for estrogen in regulating renin-angiotensin system (RAS) expression and activity [ 18 – 28 ]. The identification of angiotensin-converting enzyme-2 (ACE2) as the host cell receptor for the SARS-CoV-1 and SARS-CoV-2 [ 29 ] coronaviruses has brought attention to the functions of this enzyme outside the domain of its now established role in modulating angiotensin II (Ang II) metabolism as part of the RAS [ 30 ].…”