TY - JOUR

T1 - Modulation of hypochlorous acid (HOCl) induced damage to vascular smooth muscle cells by thiocyanate and selenium analogues

AU - Flouda, Konstantina

AU - Gammelgaard, Bente

AU - Davies, Michael J.

AU - Hawkins, Clare L.

PY - 2021/5

Y1 - 2021/5

N2 - The production of hypochlorous acid (HOCl) by myeloperoxidase (MPO) plays a key role in immune defense, but also induces host tissue damage, particularly in chronic inflammatory pathologies, including atherosclerosis. This has sparked interest in the development of therapeutic approaches that decrease HOCl formation during chronic inflammation, including the use of alternative MPO substrates. Thiocyanate (SCN−) supplementation decreases HOCl production by favouring formation of hypothiocyanous acid (HOSCN), which is more selectively toxic to bacterial cells. Selenium-containing compounds are also attractive therapeutic agents as they react rapidly with HOCl and can be catalytically recycled. In this study, we examined the ability of SCN−, selenocyanate (SeCN−) and selenomethionine (SeMet) to modulate HOCl-induced damage to human coronary artery smooth muscle cells (HCASMC), which are critical to both normal vessel function and lesion formation in atherosclerosis. Addition of SCN− prevented HOCl-induced cell death, altered the pattern and extent of intracellular thiol oxidation, and decreased perturbations to calcium homeostasis and pro-inflammatory signaling. Protection was also observed with SeCN− and SeMet, though SeMet was less effective than SeCN− and SCN−. Amelioration of damage was detected with sub-stoichiometric ratios of the added compound to HOCl. The effects of SCN− are consistent with conversion of HOCl to HOSCN. Whilst SeCN− prevented HOCl-induced damage to a similar extent to SCN−, the resulting product hyposelenocyanous acid (HOSeCN), was more toxic to HCASMC than HOSCN. These results provide support for the use of SCN− and/or selenium analogues as scavengers, to decrease HOCl-induced cellular damage and HOCl production at inflammatory sites in atherosclerosis and other pathologies.

AB - The production of hypochlorous acid (HOCl) by myeloperoxidase (MPO) plays a key role in immune defense, but also induces host tissue damage, particularly in chronic inflammatory pathologies, including atherosclerosis. This has sparked interest in the development of therapeutic approaches that decrease HOCl formation during chronic inflammation, including the use of alternative MPO substrates. Thiocyanate (SCN−) supplementation decreases HOCl production by favouring formation of hypothiocyanous acid (HOSCN), which is more selectively toxic to bacterial cells. Selenium-containing compounds are also attractive therapeutic agents as they react rapidly with HOCl and can be catalytically recycled. In this study, we examined the ability of SCN−, selenocyanate (SeCN−) and selenomethionine (SeMet) to modulate HOCl-induced damage to human coronary artery smooth muscle cells (HCASMC), which are critical to both normal vessel function and lesion formation in atherosclerosis. Addition of SCN− prevented HOCl-induced cell death, altered the pattern and extent of intracellular thiol oxidation, and decreased perturbations to calcium homeostasis and pro-inflammatory signaling. Protection was also observed with SeCN− and SeMet, though SeMet was less effective than SeCN− and SCN−. Amelioration of damage was detected with sub-stoichiometric ratios of the added compound to HOCl. The effects of SCN− are consistent with conversion of HOCl to HOSCN. Whilst SeCN− prevented HOCl-induced damage to a similar extent to SCN−, the resulting product hyposelenocyanous acid (HOSeCN), was more toxic to HCASMC than HOSCN. These results provide support for the use of SCN− and/or selenium analogues as scavengers, to decrease HOCl-induced cellular damage and HOCl production at inflammatory sites in atherosclerosis and other pathologies.

KW - Atherosclerosis

KW - Inflammation

KW - Myeloperoxidase

KW - Selenocyanate

KW - Selenomethionine

KW - Thiocyanate

UR - http://www.scopus.com/inward/record.url?scp=85100407655&partnerID=8YFLogxK

U2 - 10.1016/j.redox.2021.101873

DO - 10.1016/j.redox.2021.101873

M3 - Journal article

C2 - 33550113

AN - SCOPUS:85100407655

VL - 41

JO - Redox Biology

JF - Redox Biology

SN - 2213-2317

M1 - 101873

ER -