Sulfur mustard-stimulated proteases and their inhibitors in a cultured normal human epidermal keratinocytes model: A potential approach for anti-vesicant drug development

NAD+ in sulfur mustard toxicity

Sulfur mustard (SM) is a toxicant and chemical warfare agent with strong vesicant properties. The mechanisms behind SM-induced toxicity are not fully understood and no antidote or effective therapy against SM exists. Both, the risk of SM release in asymmetric conflicts or terrorist attacks and the usage of SM-derived nitrogen mustards as cancer chemotherapeutics, render the mechanisms of mustard-induced toxicity a highly relevant research subject. Herein, we review a central role of the abundant cellular molecule nicotinamide adenine dinucleotide (NAD⁺) in molecular mechanisms underlying SM toxicity. We also discuss the potential beneficial effects of NAD⁺ precursors in counteracting SM-induced damage.

The impact of particulate matter (PM2.5) on skin barrier revealed by transcriptome analysis: Focusing on cholesterol metabolism

Accumulating evidence suggests that particulate matter (PM2.5), as a major air pollutant, imposes a certain degree of destruction and toxicity to the skin. It particularly impairs the structure and function of the epidermis. To study the impact of PM2.5 on the skin, transcriptome analysis was performed on PM2.5-exposed human primary keratinocytes. Functional annotation analysis demonstrates that PM2.5 significantly up-regulates cholesterol-metabolism-related genes. Via lipid extraction from PM2.5 treated three-dimensional epidermis tissue model (3D-ETM) and subsequent characterization via mass spectrometry, it was confirmed that PM2.5 significantly increases epidermal cholesterol levels in vitro. Conversely, the amount of squalene in 3D-ETM was significantly reduced by PM2.5. Interestingly, neither cholesterol nor squalene showed significant fluctuations in the green tea extract (GTE) treated epidermis tissue model under PM2.5 exposure. This study shows that PM2.5 may cause barrier disorders by increasing cholesterol synthesis, leading to transient accumulation of epidermal cholesterol and decrease of squalene. It was suggested that cholesterol and squalene, which are the key substances affecting skin barrier function, can be used as new biomarkers of skin damage induced by PM2.5. Moreover, it was demonstrated that GTE can reduce damage caused by PM2.5 exposure by not only anti-inflammatory and antioxidant mechanisms, but also by off-setting the disturbance to epidermal lipid homeostasis. This study demonstrates the strong potential of GTE as an active ingredient to be utilized in cosmetic products to effectively reduce the damage PM2.5 induces in skin.

Expression of Laminin 332 in Vesicant Skin Injury and Wound Repair

Sulfur Mustard (SM) is a potent vesicant or blistering agent. It is a highly reactive bi-functional alkylating agent that cross links proteins, DNA, and other cellular components. Laminin 332 is a heterotrimer glycoprotein and a crucial skin component that attaches the epidermal basal keratinocytes to the dermis. SM wounds histologically appear similar to Epidermolysis Bullosa (EB), human genetic blistering diseases that involve genetic changes in laminin 332. The specific mechanism of action of SM exposure is unknown, but there are several key similarities between vesicant induced cutaneous injury and the Junctional form of EB (JEB) cutaneous injury: 1) Initial alkylation causes blistering similar to JEB; 2) Initial injury is followed by protease activation and prolonged inflammation similar to the chronic inflammation observed in EB; 3) The blister plane is at the level of the lamina lucida in the Basement Membrane Zone (BMZ) for both JEB and SM-induced injury. This suggests that injury induced by vesicants is not unique and probably involves malformation of laminin 332. Understanding the role of laminin 332 in SM induced blisters may provide perspectives for future molecular therapeutic countermeasures against SM exposure.