Genetic predisposition to bullous pemphigoid

New-onset or flare-up of bullous pemphigoid associated with COVID-19 vaccines: a systematic review of case report and case series studies

Background

Numerous cutaneous manifestations have been associated with the Coronavirus Disease 2019 (COVID-19) outbreak and vaccination, but new-onset bullous pemphigoid (BP) or flaring up of pre-existing BP is a rare side effect of COVID-19 vaccines that has been mentioned to a lesser extent in the literature. Therefore, we aimed to conduct a systematic review focused on the association between the new- onset or flare-up of BP and the COVID-19 vaccination.

Method

A comprehensive literature search was conducted using PubMed (MEDLINE), Scopus, and the Web of Science databases up to 11 March 2023. The search aimed to identify English-language studies reporting new-onset or flare-ups of BP as a potential side effect of the COVID-19 vaccination. The search terms included bullous pemphigoid and COVID-19 vaccination-related MeSH terms.

Results

The systematic review of 40 articles investigating the incidence of BP in individuals who received various COVID-19 vaccines revealed pertinent findings. Among the 54 patients with new-onset BP, the median age was 72.42 years, and most were men (64%). Conversely, the median age of the 17 patients experiencing a flare-up of BP was 73.35 years, with a higher proportion of women (53%). Regarding vaccination types, a significant number of patients (56%) developed new-onset BP after receiving the BNT162b2 vaccine (Pfizer-BioNTech).

Conclusion

This study indicates a potential association between COVID-19 vaccinations, particularly mRNA vaccines, and the occurrence of BP. It suggests that this rare autoimmune disorder may be triggered as an adverse event following the COVID-19 vaccination. However, it is important to note that the majority of BP patients in our study were unaffected by the COVID-19 vaccine, and even those who experienced worsening of their conditions were managed without significant consequences. These findings provide additional evidence supporting the safety of COVID-19 vaccines. Physicians should be mindful of this uncommon adverse event and encourage patients to complete their planned vaccination schedules.

HLA inherence as a potential parameter in checkpoint inhibitor-associated autoimmune adverse event assessment

Background

The success of immunotherapy has made it a lifesaving treatment, but not without side effects. Currently, the risk factors for developing immune-related adverse events (irAEs) in patients who receive immunotherapy are poorly understood, and there is no risk-stratifying mechanism for potentially fatal irAEs. It is postulated that oncology patients with preexisting autoimmune diseases are likely to have flares on immunotherapy. However, some patients develop de novo autoimmune conditions on immunotherapy without a prior history. Literature reports have postulated that human leukocyte antigen (HLA) inherence may play a role in irAEs. However, this potential remains underexplored.

Methods

The oncology patients who developed autoimmune adverse events on immunotherapy for whom the continuation of treatment was prudent or lifesaving were selected. Of note, all nine patients received checkpoint inhibitors (CIs). Of the nine selected patients, only one had a prior history of an autoimmune condition. None of the nine selected patients had an active autoimmune condition at the time of CI initiation. Their HLA was typed, and the results were cross-referenced with the literature reports in PubMed and Google search with the corresponding autoimmune condition of each patient.

Results

Herein, we report nine patients with irAEs for whom retrospective HLA typing revealed the inherence of multiple related HLA alleles that may correspond to the autoimmune condition that they had developed on immunotherapy. It is to be mentioned that the inherence of enriched disease-related HLA alleles was shared among patients with the same irAEs. These patients developed a range of irAEs including bullous pemphigoid, pemphigus foliaceus/vulgaris, thyroiditis, vitiligo, and hepatitis on immunotherapy. Although some combinations of disease-related HLA were well reported in otherwise idiopathic autoimmune diseases, a frequently repeated HLA allele combination in our patient population was found to be rarely seen in the general population.

Conclusion

The authors suggest that an enriched inherence of disease-related HLA alleles may play a role in the genetic propensity for the development of irAEs in oncology patients, who receive immunotherapy, including CIs. Inherence of more than one or a cluster of particular autoimmune disease-related HLA alleles in patients who receive immunotherapy may unmask the corresponding autoimmune disease as the genotype inherence presents with the phenotype of the corresponding condition. It is suggested that enriched linked HLA genotypes, which are otherwise rare in the general population, may present as the corresponding phenotype of the autoimmune condition. Such clinical presentation, enhanced by immunotherapy, such as CIs, can play a role in risk stratifying patients for precision medicine and improve the outcome.

Immune cells in pemphigus vulgaris and bullous Pemphigoid: From pathogenic roles to targeting therapies

Pemphigus vulgaris (PV) and bullous pemphigoid (BP) are two major subtypes of autoimmune bullous diseases (AIBD), characterized by blisters and erosions of skin and/or mucous membranes with dysregulated immune activity. Current literature established that T and B cells are the main executors of PV and BP. Emerging evidence revealed that macrophages and related cytokines also contribute to these diseases. While the role of lymphocytes on PV and BP is well established, the definitive functions of macrophages in disease progression are not fully understood. Furthermore, current status of clinical trials targeting immune cells is poorly recapitulated in PV and BP. In this review, we summarized current knowledge in this rapidly advancing field, with emphasis on the individual functions of immune cells and their interactions, as well as ongoing clinical trials targeting immune cells, to provide novel insights in mechanistic understanding and clinical management of PV and BP.

Understanding CD4+ T cells in autoimmune bullous diseases

Autoimmune bullous diseases (AIBDs) are a group of life-threatening blistering diseases caused by autoantibodies that target proteins in the skin and mucosa. Autoantibodies are the most important mediator in the pathogenesis of AIBDs, and various immune mechanisms contribute to the production of these pathogenic autoantibodies. Recently, significant progress has been made in understanding how CD4⁺ T cells drive autoantibody production in these diseases. Here, we review the critical role of CD4⁺ T cells in the production of pathogenic autoantibodies for the initiation and perpetuation of humoral response in AIBDs. To gain an in-depth understanding of CD4⁺ T-cell pathogenicity, antigen specificity, and mechanisms of immune tolerance, this review covers comprehensive mouse and human studies of pemphigus and bullous pemphigoid. Further exploration of pathogenic CD4⁺ T cells will potentially provide immune targets for improved treatment of AIBDs.

Bullous pemphigoid and milia: prevalence and clinical laboratory findings in a Brazilian sample

Background

Bullous pemphigoid (BP) associated with milia lesions has been increasingly reported, but its prevalence has not been reported in a Brazilian BP population yet.

Objectives

To describe the occurrence and clinical-laboratorial findings of BP-milia association in a southeastern Brazilian sample.

Methods

A descriptive study based on the medical charts of 102 BP patients was accomplished. Clinical and laboratory data of BP-milia patients were compiled. Total serum IgE measurements, immunoblot assays based on basement membrane zone antigens, and HLA-DQ alleles typing were performed.

Results

Milia was evident in 8 (7.8%) BP patients, five males, aged between 46 and 88 years. Increased total IgE levels were determined in 7 (87.5%) of the eight patients. In five of eight patients, immunoblotting showed IgG reactivity against the BP180-NC16a domain but not against collagen VII or laminin-332; it also revealed reactivity against the BP180 C-terminal domain or LAD-1, or both in four of them. The HLA-DQB1*03:01 and HLA-DQA1*05:05 alleles were identified in three of five BP-milia patients. Moreover, three of five cases presented the HLA-DQB1*06 allelic group.

Study limitations

HLA determination was performed in five patients.

Conclusions

Milia formation in BP patients seems to be less uncommon than previously admitted. Laboratory data revealed increased IgE; autoantibodies against the BP180 C-terminal domain or LAD-1, or both; and the HLA-DQB1*06 allelic group, described for the BP-milia association. Careful determination of antibodies against basement membrane zone molecules and HLA characterization in different populations may provide further insights into this association.