The epidermal-dermal junction has a complex molecular architecture, with numerous components playing key roles in adhesion of the epidermis to the dermis. The purpose of this study was to examine structural components of the epidermal-dermal junction as potential targets for toxicity by
lewisite (dichloro(2-chlorovinyl)arsine). This was accomplished by (1) immunocytochemical mapping of
laminin,
type IV collagen, and
bullous pemphigoid antigen (BPA) in
lewisite-treated isolated perfused porcine skin flaps (IPPSF), (2) evaluation of
protease activity in IPPSF
blister fluid against
laminin substrate from murine
EHS tumor and human keratinocytes, and (3) examination of human keratinocyte
laminin for direct chemical modification by
lewisite.
Lewisite-induced epidermal-dermal separation was localized to the lamina lucida. Localization of the separation suggested that
laminin, a cysteine-rich and highly
protease-sensitive adhesive
glycoprotein, is a potential target for
lewisite action. It was hypothesized that chemical modification of
laminin directly (via chemical alkylation of
laminin thiols by the arsenical) or indirectly (due to
lewisite-induced cytotoxic release of
proteases) could result in
blister formation. Employing sensitive methodology, no evidence of proteolytic activity against
EHS tumor laminin or human keratinocyte
laminin was identified in the
blister fluid. In addition, no evidence for direct chemical modification of
laminin by
lewisite was demonstrated. However, up to 36% of the
thiol groups in human keratinocyte
laminin immunoprecipitates was potentially available for reaction with
alkylating agents. While these studies did not demonstrate a
lewisite-induced chemical modification of
laminin, they do not rule out the possibility that other adhesive molecules of the basement membrane are targets for
lewisite action. Further evaluation of the molecular role that these binding modalities play in
vesicant-induced separation may provide new insights into therapeutic and prophylactic strategies against the toxicity of such compounds and contribute to a better understanding of basement membrane biochemistry.