Acute and long-term transcriptional responses in sulfur mustard-exposed SKH-1 hairless mouse skin.

Sulfur mustard (HD) ranks among the alkylating chemical warfare agents. Skin contact with HD produces an inflammatory response that evolves into separation at the epidermal-dermal junction conducting to blistering and epidermis necrosis. Up to now, current treatment strategies of HD burns have solely consisted in symptomatic management of skin damage. Therapeutic efficacy studies are still being conducted; classically using appropriate animal skin toxicity models. In order to substantiate the use of SKH-1 hairless mouse as an appropriate model for HD-induced skin lesions, we investigate the time-dependent quantitative gene expression of various selected transcripts associated to the dorsal skin exposure to HD saturated vapors. Using quantitative real time polymerase chain reaction (RT-qPCR), the expression of interleukins (IL-1ß and IL-6), tumor necrosis factor (TNF)-α, macrophage inflammatory proteins (MIP)-2α (also called Cxcl2) and MIP-1αR (also called Ccr1), matrix metalloproteases (MMP-9 and MMP-2), laminin γ2 monomer (Lamc2) and keratin (K)1 was determined up to 21 days after HD challenge in order to allow enough time for wound repair to begin. Specific transcript RT-qPCR analysis demonstrated that IL-6, IL-1ß, Ccr1, Cxcl2 mRNA levels increased as early as 6 h in HD-exposed skins and remained up-regulated over a 14-day period. Topical application of HD also significantly up-regulated MMP-9, TNF-α, and Lamc2 expression at specific time points. In contrast, MMP-2 mRNA levels remained unaffected by HD over the time-period considered, whereas that long-term study revealed that K1 mRNA level significantly increased only 21 days after HD challenge. Our study hereby provides first-hand evidence to substantiate a long period variation expression in the inflammatory cytokine, MMPs and structural components following cutaneous HD exposure in hairless mouse SKH-1. Our data credit the use of SKH-1 for investigating mechanisms of HD-induced skin toxicity and for the development of pharmacological countermeasures.

Stabilization of the active form(s) of human paraoxonase by human phosphate-binding protein.

While there is a consensus that human PON1 (paraoxonase-1) has a protective role, its primary biological function remains unclear. A protective role against poisoning by organophosphates [OPs (organophosphorus compounds)] drove earlier works. Clinical interest has recently focused on a protective role of PON1 against vascular diseases. PON1 resides mainly on HDL (high-density lipoprotein) particles, and converging recent works show that both its activities and stability dramatically depend on this versatile and dynamic molecular environment. The discovery that HPBP (human phosphate-binding protein) has a firm tendency to associate with PON1 has steered new directions for characterizing PON1 functional state(s). Storage stability studies provided evidence that HPBP is involved in maintaining physiologically active PON1 conformation(s). Thermal stability studies showed that human PON1 is remarkably thermostable and that its association with HPBP strongly contributes to slowing down the denaturation rate. A hybrid PON1, displaying mutations that stabilized recombinant enzyme expressed in Escherichia coli, was shown to be more thermostable than natural human PON1. Predictably, its stability was unaffected by the presence of HPBP. Synergistic efforts on characterizing natural PON1 and rPON1 (recombinant PON1) provide information for the design of future stable mutants of PON1-based bioscavengers to be used as safe and effective countermeasures to challenge OPs. Maintaining a stable environment for such administrable human rPON1 should, at least, preserve the anti-atherogenic activity of the enzyme.