Exome and Transcriptome Analysis Links Calcium Channel Pathway Aberrations to Botox Resistance in Hailey-Hailey Disease

Abstract Background The effectiveness of botulinum toxin A (BoNTA) in the treatment of Hailey-Hailey Disease (HHD) has shown heterogeneity in recent studies. However, there is currently no research investigating the underlying mechanism behind the variability in patient response. Objectives To identify potential biomarkers and elucidate the underlying mechanisms of the heterogeneity in treatment efficacy of BoNTA for HHD. Methods Twelve HHD patients were administered standardized injections of BoNTA, with the primary endpoint being ≥ 75% improvement in Improvement Global Assessment (IGA) from baseline to month 6. A comprehensive multi-omics approach, including Whole-Exome Sequencing (WES), bulk RNA sequencing (RNA-seq), single-cell RNA sequencing (scRNA-seq), and Immunohistochemistry (IHC) were utilized to investigate potential mechanisms underlying the heterogeneity of therapeutic efficacy. Additionally, an in vitro experiment was conducted to further validate cellular responses to BoNTA, providing further insights into the biological mechanisms involved. Results Ten of 12 patients (83%) achieved the primary endpoint with BoNTA treatment, while two patients (17%) showed no response at month 6. WES analysis did not find a significant association between the type of ATP2C1 genetic mutation in HHD patients and their response to BoNTA treatment. Both transcriptomic analysis and IHC of baseline skin lesions revealed an overactivated store-operated calcium entry (SOCE) pathway involving genes such as ITPKC and ORAI1 in keratinocytes, accompanied by activation of the NLRP1/IL-18/IL-1β inflammatory cascade in BoNTA resistance patients. We confirmed ATP2C1 loss triggered inflammatory responses in HaCat cells in vitro. BoNTA demonstrated potential anti-inflammatory efficacy as a calcium antagonist, while the upregulation of ORAI1/SOCE contributed to a diminished response to BoNTA. Conclusions BoNTA treatment in HHD exhibits inter-individual variability. Although ATP2C1 genetic mutation type has no direct association with patients’ response, combined transcriptomic analysis and IHC indicate the upregulation of ORAI1/SOCE pathway may potentially contribute to treatment resistance and serve as biomarkers for predicting patient responsiveness.