Antibodies against keratinocyte antigens other than desmogleins 1 and 3 can induce pemphigus vulgaris–like lesions

Abstract

IntroductionIn pemphigus vulgaris (PV), blisters develop on oral mucosa. Mucosal lesions are often followed by skin involvement. The deep intraepidermal cleft occurs between the basal cells and the overlaying spinous keratinocytes. In pemphigus foliaceus (PF), the oral mucosa is usually not involved, and cutaneous erosive lesions develop owing to a superficial epidermal split localized to the stratum granulosum. The pathophysiological mechanism causing autoimmune pemphigus is unknown and still being intensively investigated. To date, a catalogue of self-antigens, demonstrated by various authors and detection techniques to react uniquely with pemphigus IgGs, includes approximately 20 molecules with different relative molecular masses, namely: 12,18,33,47,50,52,55,59,66, 67, 68, 75, 78, 80, 85, 102, 105, 160, 180, 185/190, and 210 kDa (reviewed in ref. 1). The number of detectable target molecules varies from patient to patient and depends on the sensitivity of the detection technique, i.e., immunoblotting versus immunoprecipitation. Hypothetically, some of these bands may represent degradation products of pemphigus antigens having higher native molecular weights. The number of detectable pemphigus antigens can be substantially reduced by altering the sensitivity of the technique, as is performed when the keratinocyte protein suspension, the source of antigens, is first preabsorbed with normal human serum and then used in an immunoprecipitation assay with PV and PF sera (2, 3). Only a few protein bands remain, including the pairs of 85/130 and 85/160 kDa that were considered to represent the pathophysiologically important targets of PV and PF autoimmunity, respectively (4). Likewise, the number of clones detected in a λgt 11 keratinocyte cDNA library by PV IgG was reduced by substituting the whole PV IgG fraction with the affinity-purified IgG from a single band, the 130-kDa keratinocyte polypeptide (5).The 130-kDa PV antigen was reported to be a novel keratinocyte desmoglein (Dsg) 3 (5); the 160-kDa PF antigen, Dsg 1 (6); and the 85-kDa antigen, recognized by both PV and PF IgGs, was identified as the adhesion molecule plakoglobin (7). Autoantibodies to these adhesion molecules in pemphigus were interpreted as direct, cause-and-effect pathogenesis with autoantibody binding to an adhesion molecule inducing a dis- Pemphigus is an autoimmune disease of skin adhesion associated with autoantibodies against a number of keratinocyte antigens, such as the adhesion molecules desmoglein (Dsg) 1 and 3 and acetylcholine receptors. The notion that anti-Dsg antibodies alone are responsible for blisters in patients with pemphigus vulgaris (PV) stems from the ability of rDsg1 and rDsg3 to absorb antibodies that cause PV-like skin blisters in neonatal mice. Here, we demonstrate that PV IgGs eluted from rDsg1-Ig-His and rDsg3-Ig-His show similar antigenic profiles, including the 38-, 43-, 115-, and 190-kDa keratinocyte proteins and a non-Dsg 3 130-kDa polypeptide present in keratinocytes from Dsg 3 knockout mouse. We injected i...

Pemphigus Vulgaris IgG and Methylprednisolone Exhibit Reciprocal Effects on Keratinocytes

“…MP-Passive transfer of PV IgG to neonatal Balb/c mice caused gross and microscopic changes consistent with experimental pemphigus in vivo, as reported elsewhere (3,57,58). We first determined the dose of PV IgG appropriate for testing the clinical efficacy of MP.…”

“…The titers of antikeratinocyte antibodies in the sera of PV patients ranged from 1:80 to 1:1280 by indirect IF on the monkey esophagus substrate. All 5 sera contained high levels of both anti-Dsg 1 and anti-Dsg 3 autoantibodies determined by enzyme-linked immunosorbent assay, as described previously (57). The enzyme-linked immunosorbent assay values ranged from 46 to 170 for anti-Dsg 1 antibody and 83-229 for anti-Dsg 3 antibody.…”

“…All IgG fractions were isolated using 40% ammonium sulfate followed by dialysis against phosphate-buffered saline (PBS; Sigma), lyophilized, weighed, and reconstituted in PBS, as detailed elsewhere (57,58). This study had been approved by the University of California, Davis, Human Subjects Review Committee.…”

“…The keratinocyte adhesion molecules were immunoprecipitated (57) from the supernatants using primary monoclonal antibodies to Dsg 3, E-Cad, ␤-Cat, or ␥-Cat and protein A-agarose (Sigma). The immune complexes were dissolved in a sample buffer (50 mM Tris-HCl, 10% glycerol, 2% SDS, and 1% ␤-mercaptoethanol (pH 6.8)), resolved by 7.5% SDS-PAGE, electroblotted, and analyzed with the PhosphorImager feature of the Storm TM system, as described by us previously (57). Both the amount of radioactivity in each band and the intensity of its staining by a specific antibody were analyzed using the ImageQuant analytic software (Amersham Biosciences).…”

Multiplexed autoantigen microarrays identify HLA as a key driver of anti-desmoglein and -non-desmoglein reactivities in pemphigus

“…The presence of pathogenic autoAbs directed against non-Dsg targets could account for these findings. Early studies established the presence of non-Dsg autoAbs in PV sera by showing that PVIgG depleted of anti-Dsg3 Abs recognized a number of non-Dsg antigens (15), and subsequent work identified several specific non-Dsg proteins as targets of autoAbs in PV (9,(16)(17)(18)(19)(20).…”