A genome-wide meta-analysis of palmoplantar pustulosis implicates T H 2 responses and cigarette smoking in disease pathogenesis.

Background: Palmoplantar pustulosis (PPP) is an inflammatory skin disorder that mostly affects smokers and manifests with painful pustular eruptions on the palms and soles. Although the disease can present with concurrent plaque psoriasis, TNF and IL-17/IL-23 inhibitors show limited efficacy. There is therefore a pressing need to uncover PPP disease drivers and therapeutic targets.
Objectives: We sought to identify genetic determinants of PPP and investigate whether cigarette smoking contributes to disease pathogenesis.
Methods: We performed a genome-wide association meta-analysis of 3 North-European cohorts (n = 1,456 PPP cases and 402,050 controls). We then used the scGWAS program to investigate the cell-type specificity of the association signals. We also undertook genetic correlation analyses to examine the similarities between PPP and other immune-mediated diseases. Finally, we applied Mendelian randomization to analyze the causal relationship between cigarette smoking and PPP.
Results: We found that PPP is not associated with the main genetic determinants of plaque psoriasis. Conversely, we identified genome-wide significant associations with the FCGR3A/FCGR3B and CCHCR1 loci. We also observed 13 suggestive (P < 5 × 10 ^-6 ) susceptibility regions, including the IL4/IL13 interval. Accordingly, we demonstrated a significant genetic correlation between PPP and T _H 2-mediated diseases such as atopic dermatitis and ulcerative colitis. We also found that genes mapping to PPP-associated intervals were preferentially expressed in dendritic cells and often implicated in T-cell activation pathways. Finally, we undertook a Mendelian randomization analysis, which supported a causal role of cigarette smoking in PPP.
Conclusions: The first genome-wide association study of PPP points to a pathogenic role for deregulated T _H 2 responses and cigarette smoking.
Competing Interests: Disclosure statement This work was supported by NIHR BioResource Centre Maudsley, National Institute for Health Research Maudsley Biomedical Research Centre (BRC) at South London and Maudsley NHS Foundation Trust and Institute of Psychiatry, Psychology and Neuroscience (IoPPN), King’s College London. We gratefully acknowledge capital equipment funding from the Maudsley Charity (grant no. 980) and Guy’s and St Thomas’s Charity (grant no. STR130505). The work was also supported by the NIHR Manchester Biomedical Research Centre (grant no. NIHR203308). The Trøndelag Health Study (HUNT) is a collaboration between HUNT Research Centre (Faculty of Medicine and Health Sciences, NTNU, Norwegian University of Science and Technology), Trøndelag County Council, Central Norway Regional Health Authority, and the Norwegian Institute of Public Health. The genotyping in HUNT was financed by the National Institutes of Health; University of Michigan; the Research Council of Norway; the Liaison Committee for Education, Research and Innovation in Central Norway; and the Joint Research Committee between St Olavs Hospital and the Faculty of Medicine and Health Sciences, NTNU. The APRICOT trial was funded by the Efficacy and Mechanism Evaluation (EME) Programme, an MRC and NIHR partnership (grant no. EME 13/50/17). This study was supported by Boehringer-Ingelheim and by the Psoriasis Association (grant nos. BSTOP50/5 and PhD studentship ST3/20 to A.H.C.). Z.Q.L. was supported by the Talent Development Fund of KK Women’s and Children’s Hospital, Singapore. N.J.R. is an NIHR Senior Investigator and is also supported by NIHR Newcastle Biomedical Research Centre, NIHR Newcastle In Vitro Diagnostics Co-operative, and NIHR Newcastle Patient Safety Research Collaboration. The views expressed are those of the author(s) and not necessarily those of the NHS, Department of Health, or King’s College London. None of the funders was involved in study design; in the collection, analysis, and interpretation of data; in the writing of the report; and in the decision to submit the article for publication. Disclosure of potential conflict of interest: F. Capon has received grants and consultancy fees from Boehringer-Ingelheim. A. D. Burden has received consultancy fees from Boehringer-Ingelheim. C. E. M. Griffiths has received research grants and/or honoraria from AbbVie, Almirall, Anaptysbio, Boehringer-Ingelheim, Bristol Meyers Squibb, Evelo, GlaxoSmithKline, Inmagene, Janssen, Lilly, ONO Pharmaceuticals, Novartis, Pfizer, and UCB. P. Baum and S. Visvanathan are Boehringer-Ingelheim employees. S. Wahie has had nonfinancial support (sponsorship to attend dermatology conferences) from Janssen, AbbVie, Novartis, Almirall, and UCB. J. N. Barker declares paid activities as an advisor and speaker for AbbVie, Amgen, Boehringer-Ingelheim, Bristol Myers Squibb, Johnson & Johnson, Lilly, and Novartis. The rest of the authors declare that they have no relevant conflicts of interest.
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