The role of sodium thiocyanate supplementation during dextran sodium sulphate-stimulated experimental colitis

Environmental thiocyanate exposure was associated with oral health-related productivity loss among US adults: results from NHANES

The aim of this study is to examine the environmental exposure to perchlorate, nitrate, and thiocyanate and their associations with oral health-related productivity loss (PL) in general population. A total of 13,554 participants were enrolled from the National Health and Nutrition Examination Survey. Urinary perchlorate, nitrate, and thiocyanate were measured using ion chromatography coupled with electrospray tandem mass spectrometry. Multivariable linear and logistic regressions were performed to explore the associations between urinary perchlorate, nitrate, and thiocyanate with the prevalence of PL. Restricted cubic splines were used to explore the nonlinearity. There are 636 PL cases. There was higher urinary level of thiocyanate in PL group. We found that compared with the lowest quartile, thiocyanate was associated with PL (odds ratio 0.72, 95% confidence interval [0.53, 0.98]; p = 0.039) in the highest quartile. Restricted cubic spines reveled that urinary thiocyanate was L-shaped associated with PL with the infection point of 1.35. Urinary thiocyanate was L-shaped associated with PL with the infection point of 1.35.

Halogenation Activity of Mammalian Heme Peroxidases

Mammalian heme peroxidases are fascinating due to their unique peculiarity of oxidizing (pseudo)halides under physiologically relevant conditions. These proteins are able either to incorporate oxidized halides into substrates adjacent to the active site or to generate different oxidized (pseudo)halogenated species, which can take part in multiple (pseudo)halogenation and oxidation reactions with cell and tissue constituents. The present article reviews basic biochemical and redox mechanisms of (pseudo)halogenation activity as well as the physiological role of heme peroxidases. Thyroid peroxidase and peroxidasin are key enzymes for thyroid hormone synthesis and the formation of functional cross-links in collagen IV during basement membrane formation. Special attention is directed to the properties, enzymatic mechanisms, and resulting (pseudo)halogenated products of the immunologically relevant proteins such as myeloperoxidase, eosinophil peroxidase, and lactoperoxidase. The potential role of the (pseudo)halogenated products (hypochlorous acid, hypobromous acid, hypothiocyanite, and cyanate) of these three heme peroxidases is further discussed.

The Association Between Environmental Perchlorate, Nitrate, and Thiocyanate Exposure and Oral Pain in NHANES

Aim

To examine the human exposure to perchlorate, nitrate, and thiocyanate, and their associations with oral pain (OP) in the general population from the U.S.

Methods

A total of 13,554 participants were enrolled in the National Health and Nutrition Examination Survey. The urinary perchlorate, nitrate, and thiocyanate were measured using ion chromatography coupled with an electrospray tandem mass spectrometry. The multivariable linear and logistic regressions were performed to explore the associations of the urinary perchlorate, nitrate, and thiocyanate, with the prevalence of oral pain. Restricted cubic splines were used to explore the non-linearity.

Results

There are 3,129 OP cases. There was a higher urinary level of perchlorate, nitrate, and thiocyanate in OP. We found that urinary thiocyanate was positively associated with OP (odds ratio [OR] = 1.06; [1, 1.13]; p = 0.049). Restricted cubic spines revealed that urinary thiocyanate was in a U-shape association with OP.

Conclusions

Urinary thiocyanate was in a U-shape association with OP, suggesting that we should keep the exposure of thiocyanate under a reasonable range.

Myeloperoxidase Modulates Hydrogen Peroxide Mediated Cellular Damage in Murine Macrophages

Myeloperoxidase (MPO) is involved in the development of many chronic inflammatory diseases, in addition to its key role in innate immune defenses. This is attributed to the excessive production of hypochlorous acid (HOCl) by MPO at inflammatory sites, which causes tissue damage. This has sparked wide interest in the development of therapeutic approaches to prevent HOCl-induced cellular damage including supplementation with thiocyanate (SCN^-) as an alternative substrate for MPO. In this study, we used an enzymatic system composed of glucose oxidase (GO), glucose, and MPO in the absence and presence of SCN^-, to investigate the effects of generating a continuous flux of oxidants on macrophage cell function. Our studies show the generation of hydrogen peroxide (H₂O₂) by glucose and GO results in a dose- and time-dependent decrease in metabolic activity and cell viability, and the activation of stress-related signaling pathways. Interestingly, these damaging effects were attenuated by the addition of MPO to form HOCl. Supplementation with SCN^-, which favors the formation of hypothiocyanous acid, could reverse this effect. Addition of MPO also resulted in upregulation of the antioxidant gene, NAD(P)H:quinone acceptor oxidoreductase 1. This study provides new insights into the role of MPO in the modulation of macrophage function, which may be relevant to inflammatory pathologies.

The Role of Thiocyanate in Modulating Myeloperoxidase Activity during Disease

Thiocyanate (SCN⁻) is a pseudohalide anion omnipresent across mammals and is particularly concentrated in secretions within the oral cavity, digestive tract and airway. Thiocyanate can outcompete chlorine anions and other halides (F⁻, Br⁻, I⁻) as substrates for myeloperoxidase by undergoing two-electron oxidation with hydrogen peroxide. This forms their respective hypohalous acids (HOX where X⁻ = halides) and in the case of thiocyanate, hypothiocyanous acid (HOSCN), which is also a bactericidal oxidative species involved in the regulation of commensal and pathogenic microflora. Disease may dysregulate redox processes and cause imbalances in the oxidative profile, where typically favoured oxidative species, such as hypochlorous acid (HOCl), result in an overabundance of chlorinated protein residues. As such, the pharmacological capacity of thiocyanate has been recently investigated for its ability to modulate myeloperoxidase activity for HOSCN, a less potent species relative to HOCl, although outcomes vary significantly across different disease models. To date, most studies have focused on therapeutic effects in respiratory and cardiovascular animal models. However, we note other conditions such as rheumatic arthritis where SCN⁻ administration may worsen patient outcomes. Here, we discuss the pathophysiological role of SCN⁻ in diseases where MPO is implicated.