Pemphigus vulgaris disease activity: The role of antibodies to desmogleins and their isotype

Immunocytometric Analysis of Oral Pemphigus vulgaris Patients after Treatment with Rituximab as Adjuvant

Background: B-cell depletion therapy was demonstrated to be a valid and safe alternative as an adjuvant in oral-pharyngeal pemphigus vulgaris (OPV) patients. We aimed to assess its effects on anti-desmoglein (Dsg) 1 and 3 and leukocytes subsets profile in these patients’ population. Methods and Materials: We evaluated the immunologic profile of 10 OPV patients treated with RTX as adjuvant by using the ELISA testing for anti-Dsg-1 and -3 titers and the immunophenotyping for B and T-cell lymphocyte subpopulations and compared them with the PDAI score for clinical remission. Results: A significant difference in medians between baseline, end of RTX therapy, and 6 months after RTX therapy was observed in Dsg-3 titer (p < 0.001), in the CD8 (p = 0.009), and CD20 counts (p < 0.001). Multiple comparisons after Bonferroni adjustment confirmed such significant differences mainly between baseline and the end of RTX therapy and baseline and 6 months after RTX therapy. Only the anti-Dsg-3 titer at the end of RTX therapy demonstrated a slight positive correlation with the PDAI score at baseline (p = 0.046, r = 0.652). Conclusions: B-cell depletion adjuvant therapy in OPV patients demonstrated a significant impact on anti-Dsg-3 titer and B and T-cell lymphocyte subpopulations profile.

Analysis of clinical characteristics, prognosis and antibody pathogenicity of pemphigus patients positive for anti-desmoglein IgG autoantibodies in remission: a retrospective cohort study

BACKGROUND

The detection of serum anti-desmoglein (Dsg) IgG autoantibodies has been reported to be useful for assessment of disease activity in pemphigus. However, previous studies have reported that anti-Dsg autoantibodies remain detectable in some patients without active pemphigus lesions.

OBJECTIVES

To investigate the clinical characteristics and antibody pathogenicity of pemphigus patients positive for anti-Dsg IgG autoantibodies in remission.

METHODS

We retrospectively investigated pemphigus patients with a history of clinical remission who visited the Department of Dermatology of Keio University during 2019 and 2020. The antibody pathogenicity was assessed by bead aggregation assay.

RESULTS

When patients were recognized as having entered remission (PDAI = 0 and PSL ≦ 10 mg/day for 2 months), serum autoantibodies against Dsg were detected in 72 of 132 patients (54.5%, positive group; PG), but were not detected in 60 patients (45.5%, negative group; NG). Anti-Dsg antibody titres in remission declined from the active phase in 33 patients in the PG for whom data were available. There were no differences in the chance of reducing PSL to 5 mg/day (P = 0.885) and rate of relapse (P = 0.279) between PG and NG, but fewer patients in PG discontinued corticosteroids (P = 0.004). The ability of patients' sera to block aggregation of Dsg/desmocollin beads was significantly reduced in remission compared to the active phase. However, our results revealed that whole sera in remission still had pathogenic activity in seven of nine patients, and the approximately equal amounts of anti-Dsg antibodies in active phase and remission showed similar pathogenicity.

CONCLUSIONS

This study will provide guidance in cases where autoantibodies are found to be positive in pemphigus patients during remission or steroid reduction.

Critical appraisal of different triggering pathways for the pathobiology of pemphigus vulgaris-A review

Pemphigus vulgaris is an autoimmune blistering disease with an increased potential for mortality. The epithelium is key in understanding the pathobiology as it is specialized to perform functions like mechanical protection, immunological defense, and proprioception. In order to perform these array of functions, epithelial integrity is important. This integrity is maintained by a host of molecules which orchestrate the ability of the keratinocytes to function as a single unit. Desmoglein 3 antibodies formed in genetically susceptible individuals are known to cause the disruption of the intact oral mucosa leading to the formation of blisters in pemphigus vulgaris patients. However, there are underlying complex triggering pathways leading to the clinical disease. The aim of the review is to congregate and critically appraise the various triggering pathways which contribute toward the pathobiology of pemphigus vulgaris. Articles relevant to the pathobiology of pemphigus vulgaris were identified from various search databases till the year 2020. The pathogenesis of pemphigus vulgaris is complex, and it involves an in-depth understanding of the various predisposing factors, provoking factors, and progression mechanisms. Congregation of the various triggering pathways will open our minds to understand pemphigus vulgaris better and in turn develop a reliable treatment in the near future.

Safety, Tolerability, and Activity of ALXN1830 Targeting the Neonatal Fc Receptor in Chronic Pemphigus

Pemphigus is a debilitating IgG-mediated autoimmune disease requiring better tolerated, more targeted, and rapid onset therapies. ALXN1830 is a humanized IgG4 antibody that blocks neonatal Fc receptor interactions with IgG. A multicenter, open-label safety and tolerability phase 1b/2 trial (NCT03075904) was conducted in North America from July 2017 to January 2019 and included patients aged ≥18 years with a confirmed diagnosis of pemphigus (vulgaris or foliaceus) and active disease. Dosing included five weekly intravenous doses of ALXN1830 (10 mg/kg) and follow-up through day 112 (study termination). Pharmacokinetics, pharmacodynamics, safety, and efficacy, as evaluated by determining the change in the median pemphigus disease area index, were determined. In this pilot study of eight patients, five weekly infusions of ALXN1830 produced a rapid improvement in the pemphigus disease area index score within 14 days of the first dose. Pemphigus disease area index improvement increased further together with reductions in IgG, circulating immune complexes of IgG, and anti-desmoglein antibodies without affecting albumin, IgM, IgA, or C-reactive protein levels. ALXN1830 was well-tolerated, with headache as the most common adverse event. This study reveals the importance of neonatal Fc receptor in the biology of pemphigus and the potential for use of ALXN1830 in pemphigus treatment.

Mechanisms of Trx2/ASK1-Mediated Mitochondrial Injury in Pemphigus Vulgaris

Objective

Apoptotic events mediated by mitochondrial injury play an important role on the onset of Pemphigus vulgaris (PV). The thioredoxin-2 (Trx2)/apoptosis signal-regulating kinase 1 (ASK1) signaling pathway is considered a key cascade involved on the regulation of mitochondrial injury. Hence, we have investigated the regulatory mechanism of the Trx2/ASK1 signaling in PV-induced mitochondrial injury.

Methods

Serum and tissue samples were collected from clinical PV patients to detect the oxidative stress factors, cell apoptosis, and expression of members from Trx2/ASK1 signaling. HaCaT cells were cultured with the serum of PV patients and transfected with Trx2 overexpression or silencing vector. Changes in the levels of reactive oxygen species (ROS), mitochondrial membrane potential (△ψm), and apoptosis were further evaluated. A PV mouse model was established and administered with Trx2-overexpressing plasmid. The effect of ectopic Trx2 expression towards acantholysis in PV mice was observed.

Results

A series of cellular and molecular effects, including (i) increased levels of oxidative stress products, (ii) destruction of epithelial cells in the skin tissues, (iii) induction of apoptosis in keratinocytes, (iv) reduction of Trx2 protein levels, and (v) enhanced phosphorylation of ASK1, were detected in PV patients. In vitro experiments confirmed that Trx2 can inhibit ASK1 phosphorylation, alleviate ROS release, decrease △ψm, and lower the apoptotic rate. Injection of Trx2-overexpressing vectors in vivo could also relieve acantholysis and blister formation in PV mice.

Conclusion

The Trx2/ASK1 signaling pathway regulates the incidence of PV mediated by mitochondrial injury.

Clinical presentation and diagnostic delay in pemphigus vulgaris: A prospective study from Turkey

BACKGROUND

To evaluate the diagnostic patterns and factors that may influence delays in the diagnosis of pemphigus vulgaris (PV) with oral involvement.

MATERIALS AND METHODS

In this prospective cohort study, 36 newly diagnosed PV patients with oral involvement were clinically examined and interviewed about the natural history of the oral lesions, number of medical consultations (Med consultation), medical treatment history, and diagnostic delay time (DD time).

RESULTS

Thirty (83%) PV patients presented initially with oral mucosal involvement (OMI) and 6 (17%) presented initially with skin involvement (SI). The mean DD time was 6.19 ± 3.82 months, and the mean number of Med consultation was 5.8 (n = 36). The means of all the parameters were significantly higher for the OMI patients than for the SI patients (P < .05). All of the patients with OMI had been misdiagnosed. The DD time was significantly longer in patients who presented initially with desquamative gingivitis (8.25 ± 3.81) than patients who presented with ulcers and erosions (4.78 ± 1.11) (P < .05). There was a statistically significant positive correlation between DD time and Med consultation (r = 0.91).

CONCLUSION

Even with the high frequency of oral involvement and easy access to the oral cavity, diagnostic delays are still common for patients with oral PV. This underlines the need for education to improve healthcare providers' awareness and knowledge of the clinical oral presentation of PV.

A Comparative Analysis of CD32A and CD16A Polymorphisms in Relation to Autoimmune Responses in Pemphigus Diseases and Subepithelial Autoimmune Blistering Disorders

Autoimmune blistering dermatoses (ABDs) are characterized by autoantibodies to keratinocyte surface antigens and molecules within the dermal–epidermal junction causing disruption of skin integrity. The affinity of Fc receptors (FcRs) causing an autoimmune response in ABDs may vary based on single-nucleotide polymorphisms (SNPs) in FcRs determining the course of disease. This study aimed to explore the effects of CD16A and CD32A SNPs on the autoimmune response in several ABDs. In total, 61 ABDs patients were investigated. ELISA tests, direct immunofluorescence (DIF), TaqMan SNP Genotyping Assays, and statistical analyses were performed. The CA genotype (composed of allele C and A) of rs396991 in CD16A had a higher affinity for tissue-bound IgG1 in pemphigus and for C3 in subepithelial ABDs, showing statistical significance. The greatest relative risk (odds ratio) was reported for AA (rs396991 of CD16A) and CC (rs1801274 of CD32A) homozygotes. There were no statistically significant differences between certain genotypes and specific circulating autoantibodies (anti-DSG1, anti-DSG3 IgG in pemphigus; anti-BP180, anti-BP230 IgG) in subepithelial ABDs. Our findings indicated that rs396991 in CD16A may be of greater importance in ABDs development. Moreover, FcR polymorphisms appeared to have a greater impact on tissue-bound antibodies detected using DIF than circulating serum antibodies in ABDs.