Increased Fibrosis in a Mouse Model of Anti-Laminin 332 Mucous Membrane Pemphigoid Remains Unaltered by Inhibition of Aldehyde Dehydrogenase

Abstract

Mucous membrane pemphigoid (MMP) is an autoimmune blistering disease characterized by autoantibodies against the basal membrane zone of skin and surface-close epithelia and predominant mucosal lesions. The oral cavity and conjunctivae are most frequently affected, albeit clinical manifestations can also occur on the skin. MMP-associated lesions outside the oral cavity typically lead to scarring. Mechanisms underlying scarring are largely unknown in MMP and effective treatment options are limited. Herein, we assessed the collagen architecture in tissue samples of an antibody-transfer mouse model of anti-laminin-332 MMP. In MMP mice, increased collagen fibril density was observed in skin and conjunctival lesions compared to mice injected with normal rabbit IgG. The extracellular matrix of MMP skin samples also showed altered post-translational collagen cross-linking with increased levels of both lysine- and hydroxylysine-derived collagen crosslinks supporting the fibrotic phenotype in experimental MMP compared to control animals. In addition, we evaluated a potential anti-fibrotic therapy in experimental anti-laminin-332 MMP using disulfiram, an inhibitor of the aldehyde dehydrogenase (ALDH), which has been implicated in immune-mediated mucosal scarring. In addition, disulfiram also acts as a copper chelator that was shown to block lysyl oxidase activity, an enzyme involved in formation of collagen crosslinks. Topical use of disulfiram (300 μM in 2% [w/v] methocel) did not improve ocular lesions in experimental MMP over the 12-day treatment period in disulfiram-treated mice compared to vehicle-treated mice (n=8/group). Furthermore, C57BL6/J mice (n=8/group) were treated prophylactically with 200 mg/kg p.o. disulfiram or the solvent once daily over a period of 12 days. Systemic treatment did not show any reduction in the severity of oral and ocular lesions in MMP mice, albeit some improvement in skin lesions was observed in disulfiram- vs. vehicle-treated mice (p=0.052). No reduction in fibrosis was seen, as assessed by immunohistochemistry. Whilst blocking of ALDH failed to significantly ameliorate disease activity, our data provide new insight into fibrotic processes highlighting changes in the collagenous matrix and cross-linking patterns in IgG-mediated MMP.

Autoimmunity against laminin 332

“…However, disulfiram was not effective in the anti-laminin 332 mouse model. Here, the same dosage and application of disulfiram was not able to reduce the severity of the conjunctival lesions ( 101 ).…”

“…Biopsies of the palpebral conjunctiva and the skin collected 28 days after the initiation of this model revealed highly condensed collagen fibrils in picro-sirius red staining and trichrome histological staining. In addition, biochemical analysis provided results on altered collagen-cross-linking signaling pathways in these tissues that are associated with fibrosis ( 101 ). Furthermore, the previously published upregulation of aldehyde dehydrogenase (ALDH1) in conjunctiva and in fibroblasts isolated from MMP patients with severe eye involvement, could be verified by transcriptome analysis of perilesional skin from this model ( 102 ).…”

Bullous pemphigoid induced by IgG targeting type XVII collagen non‐NC16A/NC15A extracellular domains is driven by Fc gamma receptor‐ and complement‐mediated effector mechanisms and is ameliorated by neonatal Fc receptor blockade

“…The percentage of the ABSA was determined every 4 days (D4, D8, D12) under anesthesia. Disease scoring and endoscopy of the oral cavity is based on a previously established mouse model of epidermolysis bullosa acquisita [36] and MMP [37,38].…”

A life for autoimmune blistering diseases: in memoriam Detlef Zillikens

“…This article describes the first mouse model for mucous membrane pemphigoid that reflects major clinical and immunological characteristics of the human disease (96). In this model, like in patients with mucous membrane pemphigoid, dapsone significantly reduced skin and oral lesions and ocular inflammation that leads to fibrosis (97,98). This model will be instrumental in characterizing key inflammatory pathways and potential novel therapeutic agents for this devastating disease.…”