Recent advances in hidradenitis suppurativa: Role of race, genetics, and immunology

Improving hidradenitis suppurativa management: consensus statements from physicians and patients' perspectives

Hidradenitis suppurativa (HS) is a frequent chronic inflammatory skin condition primarily affecting areas rich in apocrine sweat glands, presenting with comedones, papules, nodules, and abscesses, as well as tunnels and hypertrophic scarring. Despite its prevalence and impact on quality of life, the pathogenesis of HS remains incompletely understood. Notably, its diagnosis often suffers from delays and misidentification, therefore an improved education for healthcare providers is mandatory. Moreover, HS is frequently associated with systemic comorbidities and a multidisciplinary approach is suggested for its management. Recognizing these challenges, a group of Italian HS experts and patients convened to develop consensus guidelines via the Nominal Group Technique. Through iterative meetings and remote collaboration, they identified key areas for improvement and formulated consensus statements to guide healthcare providers in delivering optimal care. This collaborative effort highlights the importance of standardized approaches and interdisciplinary collaboration in managing HS effectively.

Response to adalimumab in Caucasian and Asian patients with hidradenitis suppurativa: A retrospective cohort study of an Australian cohort stratified by patient-reported ethnicity

BACKGROUND/OBJECTIVES

Caucasian and Asian patients with hidradenitis suppurativa demonstrate significant differences with regard to age, gender and body mass index. Demographic characteristics are known to influence the efficacy and drug survival of hidradenitis suppurativa therapeutics including biologic therapies. What remains unknown is the impact of ethnicity upon the efficacy of therapeutics once demographic and disease characteristics have been taken into account. This is an important question given the expansion of biologic therapies for HS into the global patient community.

METHODS

We assessed 170 patients from a single HS specialist centre in Australia stratified by patient-identified ethnicity including those identifying as either Caucasian or Asian.

RESULTS

Asian patients demonstrated lower BMI, higher rates of smoking and greater odds of Hurley stage 3 disease with tunnels than Caucasian patients in line with the reported literature. There was no significant difference between percentage of individuals achieving HiSCR50 or IHS4-55 at Week 16. Significant differences were seen in median time to secondary loss of response, and Kaplan-Meier curve analysis showed a significant difference between curves when stratified by patient-reported ethnicity. Cox regression analysis demonstrated after accounting for age, gender, BMI, smoking and Hurley stage, the significance of ethnicity in influencing time to secondary loss of response disappears.

CONCLUSIONS

Caucasian or Asian ethnicity does not influence response to adalimumab treatment on patients with hidradenitis suppurativa.

Hidradenitis suppurativa: Detangling phenotypes and identifying common denominators

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease with a severe impact on patients' quality of life through its recurrent and painful nature, as well as its comorbidity burden. The shift in the pathogenic paradigm from a condition of the apocrine glands to an autoinflammatory disease associated with follicular destruction has rendered its understanding difficult, as there are still large gaps in pinpointing the underlying mechanisms, which cannot currently explain the existing clinical variation and as a result, translate into suboptimal therapy. Multifactorial involvement is hypothesized, with an implication of genetic mutations, microbiome dysbiosis, cytokine upregulation and environmental factors. Clinical observation is fundamental for diagnosis, however, the marked heterogeneity in presentation leads to delays in detection and challenges in treatment selection, showcasing clear limits in defining the link between genetic aspects of HS, the role of epigenetic factors and its pathogenic pathways. There have been attempts to formulate phenotypes that could aid in prognostication and management, however, current classification schemata show significant overlap and no validation through longitudinal studies. In this context, nomenclature poses a great challenge due to the lack of global agreement in the definition of lesions, which should be addressed by future research to enable simplified recognition and allow for more precise severity scoring. This could be complemented by the addition of extra dermatologic findings or paraclinical assessment in constructing phenotypes. The development of valid, predictive and reliable classifications of HS may lead to an improvement in comprehending its pathophysiology, favouring a more personalized approach in management. This could be achieved through consensus in the characterization of clinical features and data gathering, as well as validation attempts for described phenotypes. Ultimately, the genotype-endotype-phenotype correlation in HS requires targeted, systematic inquiries and should be addressed more largely to broaden the perspective on this debilitating entity.

NK and NKT cells in the pathogenesis of Hidradenitis suppurativa: Novel therapeutic strategy through targeting of CD2

Hidradenitis suppurativa (HS) is a chronic debilitating inflammatory skin disease with poorly understood pathogenesis. Single-cell RNAseq analysis of HS lesional and healthy individual skins revealed that NKT and NK cell populations were greatly expanded in HS, and they expressed elevated CD2, an activation receptor. Immunohistochemistry analyses confirmed significantly expanded numbers of CD2+ cells distributed throughout HS lesional tissue, and many co-expressed the NK marker, CD56. While CD4+ T cells were expanded in HS, CD8 T cells were rare. CD20+ B cells in HS were localized within tertiary follicle like structures. Immunofluorescence microscopy showed that NK cells (CD2 + CD56 dim ) expressing perforin, granzymes A and B were enriched within the hyperplastic follicular epidermis and tunnels of HS and juxtaposed with apoptotic cells. In contrast, NKT cells (CD2 + CD3 + CD56 bright ) primarily expressed granzyme A and were associated with α-SMA expressing fibroblasts within the fibrotic regions of the hypodermis. Keratinocytes and fibroblasts expressed high levels of CD58 (CD2 ligand) and they interacted with CD2 expressing NKT and NK cells. The NKT/NK maturation and activating cytokines, IL-12, IL-15 and IL-18, were significantly elevated in HS. Inhibition of cognate CD2-CD58 interaction with blocking anti-CD2 mAb in HS skin organotypic cultures resulted in a profound reduction of the inflammatory gene signature and secretion of inflammatory cytokines and chemokines in the culture supernate. In summary, we show that a cellular network of heterogenous NKT and NK cell populations drives inflammation, tunnel formation and fibrosis in the pathogenesis of HS. Furthermore, CD2 blockade is a viable immunotherapeutic approach for the management of HS.

Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) is a chronic disease characterized by recurrent painful abscesses and chronic sinus tracts in intertriginous areas. In the United States, HS disproportionally affects adults of African-American heritage. Depending on the severity of disease, the consequences of HS can be far-reaching, significantly affecting mental health and quality of life. In recent years, concerted research efforts have been made to better understand the pathophysiology of the disease as well as identify emerging new treatment targets. Herein, we discuss the clinical presentation, diagnostic criteria, and treatment approach of HS with a focus on skin of color.