Postexposure Application of Fas Receptor Small-Interfering RNA to Suppress Sulfur Mustard–Induced Apoptosis in Human Airway Epithelial Cells: Implication for a Therapeutic Approach

Brian M. Keyser; Devon K. Andres; Eric Nealley; Wesley W. Holmes; Betty Benton; Danielle Paradiso; Ashley Appell; Chris Carpin; Dana R. Anderson; William J. Smith; Radharaman Ray

doi:10.1124/jpet.112.199935

Abstract

Sulfur mustard (SM) is a vesicant chemical warfare and terrorism agent. Besides skin and eye injury, respiratory damage has been mainly responsible for morbidity and mortality after SM exposure. Previously, it was shown that suppressing the death receptor (DR) response by the dominant-negative Fas-associated death domain protein prior to SM exposure blocked apoptosis and microvesication in skin. Here, we studied whether antagonizing the Fas receptor (FasR) pathway by small-interfering RNA (siRNA) applied after SM exposure would prevent apoptosis and, thus, airway injury. Normal human bronchial/tracheal epithelial (NHBE) cells were used as an in vitro model with FasR siRNA, FasR agonistic antibody CH11, and FasR antagonistic antibody ZB4 as investigative tools. In NHBE cells, both SM (300 µM) and CH11 (100 ng/ml) induced caspase-3 activation, which was inhibited by FasR siRNA and ZB4, indicating that SM-induced apoptosis was via the Fas response. FasR siRNA inhibited SM-induced caspase-3 activation when added to NHBE cultures up to 8 hours after SM. Results using annexin V/propidium iodide-stained cells showed that both apoptosis and necrosis were involved in cell death due to SM; FasR siRNA decreased both apoptotic and necrotic cell populations. Bronchoalveolar lavage fluid (BALF) of rats exposed to SM (1 mg/kg, 50 minutes) revealed a significant (P < 0.05) increase in soluble Fas ligand and active caspase-3 in BALF cells. These findings suggest an intervention of Fas-mediated apoptosis as a postexposure therapeutic strategy with a therapeutic window for SM inhalation injury and possibly other respiratory diseases involving the Fas response.

Footnotes

This work was supported by the Defense Threat Reduction Agency–Joint Science and Technology Office, Medical S&T Division [Grants CBM.RESP.01.10.RC.015, 3.F0011-08-RC-C]. Additionally, this research was supported in part by an appointment to the Postgraduate Research Participation Program at the U.S. Army Medical Research Institute of Chemical Defense administered by the Oak Ridge Institute for Science and Education through an interagency agreement between the U.S. Department of Energy and U.S. Army Medical Research and Materiel Command (USAMRMC). B.M.K., W.W.H., D.R.A., and R.R. acquired funding for the research.
The views expressed in this article are those of the author(s) and do not reflect the official policy of the Department of Army, Department of Defense, or the U.S. Government. The experimental protocol was approved by the Animal Care and Use Committee at the U.S. Army Medical Research Institute of Chemical Defense and all procedures were conducted in accordance with the principles stated in the Guide for the Care and Use of Laboratory Animals and the Animal Welfare Act of 1966 (P.L. 89-544), as amended.
dx.doi.org/10.1124/jpet.112.199935.