Circulating plakin autoantibodies in a patient with erythema multiforme major: Are they pathogenic or a manifestation of epitope spreading?

Desmoplakin I/II immunohistochemical staining may be a helpful tool in differentiating cutaneous graft versus host disease from the erythema multiforme, Stevens-Johnson syndrome, and toxic epidermal necrolysis spectrum disorders

Cutaneous graft versus host disease (cGVHD) has substantial clinical and histopathologic overlap with erythema multiforme (EM), Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN). This overlap can make it difficult to distinguish these disorders in patients who have received hematopoietic transplants. We sought to evaluate the utility of Dp I/II immunohistochemical stain in differentiating EM/SJS/TEN and cGVHD in a large cohort. Skin biopsy specimens from patients with cGVHD (n = 58) and EM/SJS/TEN (n = 60) were evaluated for Dp I/II expression by immunohistochemistry. We found a statistically significant difference in Dp I/II staining between cGVHD (all grades) and EM/SJS/TEN (mean scores 1.62 and 2.14, respectively; p < 0.005), as well as between Grades 2 + 3 cGVHD and EM/SJS/TEN (mean scores 2.26 and 1.62, respectively; p < 0.005), while we did not find a significant difference between Grade 4 cGVHD and EM/SJS/TEN (mean scores 1.69 and 1.62, respectively; p = 0.71). Dp I/II immunostain may be useful for differentiating EM/SJS/TEN from Grade 2 and Grade 3 cGVHD, especially in clinically ambiguous cases without extracutaneous GVHD.

Erythema multiforme associated with anti-plakin antibodies: a multicentric retrospective case series

BACKGROUND

Erythema multiforme (EM) is a muco-cutaneous inflammatory disease mainly triggered by herpes simplex virus (HSV) recurrences. Association of EM and circulating auto-antibodies against plakins (anti-PLK-Abs [EM-PLK+]) has been reported. However, little is known about this subset of EM.

OBJECTIVES

We aimed to describe the clinical and immunological features and response to treatment of EM-PLK+.

METHODS

We conducted a retrospective multicentric study of EM-PLK+ selected from the database of the immunological laboratory of Bichat hospital, Paris, France, from January 2009 to December 2020. Anti-PLK-Abs were detected in ≥1 immunological tests: immunofluorescence assay, immunoblotting and/or ELISA. Patients with alternative diagnoses were excluded.

RESULTS

We included 29 patients (16 women, median age 25 [range 2-58] years). EM-PLK+ were mostly major (EM with ≥2 mucosal involvements; n = 24, 83%) and relapsing (≥2 flares; n = 23, 79%). Cutaneous lesions were target (n = 13, 54%) and target-like lesions (n = 9, 38%) with usual topography (acral, n = 19, 79%; limbs, n = 21, 88%). Mucosal lesions affected the mouth (n = 27, 96%) and genitalia (n = 19, 68%), with a median of 2 [range 0-5] mucous membranes. EM-PLK+ were suspected as certain or possible postherpetic (EM-HSV) in 19 cases (65.5%); no triggering factors were detected in 9 (31%) patients. Desmoplakin-I/II Abs were the most frequent anti-PLK-Abs (n = 20, 69%); envoplakin and periplakin Abs were detected in 11 and 9 cases. Relapsing EM-PLK+ (n = 23) were still active (≥1 flare within 6 months) in 13 (57%) patients despite immunosuppressive therapy (n = 8, 62%). Antiviral drugs were ineffective in preventing relapse in 15/16 (94%) EM-HSV.

CONCLUSION

The rationale for anti-PLK-Ab detection in EM is not elucidated. More systematic research of anti-PLK-Abs is warranted to better understand whether this association reflects humoral immune activity in a subset of EM or is fortuitous, related to an epitope spreading process. However, EM-PLK+ seems to be associated with major and relapsing subtypes, and difficult-to-treat cases.

Pathophysiology of the Desmo-Adhesome

Advances in our understanding of desmosomal diseases have provided a clear demonstration of the key role played by desmosomes in tissue and organ physiology, highlighting the importance of their dynamic and finely regulated structure. In this context, non-desmosomal regulatory molecules have acquired increasing relevance in the study of this organelle resulting in extending the desmosomal interactome, named the "desmo-adhesome." Spatiotemporal changes in the expression and regulation of the desmo-adhesome underlie a number of genetic, infectious, autoimmune, and malignant conditions. The aim of the present article was to examine the structural and functional relationship of the desmosome, by providing a comprehensive, yet focused overview of the constituents targeted in human disease. The inclusion of the novel regulatory network in the desmo-adhesome pathophysiology opens new avenues to a deeper understanding of desmosomal diseases, potentially unveiling pathogenic mechanisms waiting to be explored. J. Cell. Physiol. 232: 496-505, 2017. © 2016 Wiley Periodicals, Inc.

Desmosomes in disease: a guide for clinicians

The large number of diseases occurring when desmosome constituents are impaired provides striking evidence for the key role of desmosomes in maintaining tissue integrity. A detailed understanding of the molecular alterations causing desmosomal dysfunction has, in turn, underpinned the development of novel diagnostic tools. This has salient clinical implications for dentists and oral medicine practitioners because the majority of desmosomal diseases affect the oral cavity. In the present article, we review the autoimmune, infectious, genetic, and neoplastic diseases that target the desmosome, with particular emphasis on clinical manifestations, diagnostic pathways, and relevant laboratory investigations.

Oral mucosal manifestations of autoimmune skin diseases

A group of autoimmune diseases is characterised by autoantibodies against epithelial adhesion structures and/or tissue-tropic lymphocytes driving inflammatory processes resulting in specific pathology at the mucosal surfaces and the skin. The most frequent site of mucosal involvement in autoimmune diseases is the oral cavity. Broadly, these diseases include conditions affecting the cell-cell adhesion causing intra-epithelial blistering and those where autoantibodies or infiltration lymphocytes cause a loss of cell-matrix adhesion or interface inflammation. Clinically, patients present with blistering, erosions and ulcers that may affect the skin as well as further mucosal surfaces of the eyes, nose and genitalia. While the autoimmune disease may be suspected based on clinical manifestations, demonstration of tissue-bound and circulating autoantibodies, or lymphocytic infiltrates, by various methods including histological examination, direct and indirect immunofluorescence microscopy, immunoblotting and quantitative immunoassay is a prerequisite for definitive diagnosis. Given the frequency of oral involvement and the fact that oral mucosa is the initially affected site in many cases, the informed practitioner should be well acquainted with diagnostic and therapeutic aspects of autoimmune dermatosis with oral involvement. This paper reviews the pathogenesis and clinical presentation of these conditions in the oral cavity with a specific emphasis on their differential diagnosis and current management approaches.