Decoding Inflammation in Hidradenitis Suppurativa: Serum Cytokines as Biomarkers of Disease Severity and Treatment Outcome—Systematic Review

Introduction: Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease with systemic features, characterized by painful nodules, abscesses, and sinus tracts. Pro-inflammatory cytokines may serve as biomarkers of disease severity, inflammatory burden, and therapeutic response. The aim of this article is to systematically review the current evidence on serum concentrations of pro-inflammatory cytokines in patients with HS and to evaluate their potential utility as biomarkers of disease activity and personalized treatment guidance. Materials and Methods: This systematic review was conducted in accordance with the PRISMA 2020 guidelines. A literature search was performed in PubMed, Embase, and Scopus, with Google Scholar used as a supplementary source. The search included English-language publications from 2015 to 2026. The following keywords were used in combination: “cytokines”, “serum”, “hidradenitis suppurativa”, and “markers”. In addition, reference lists and citations of eligible full-text articles were manually screened. Eligible studies for inclusion were peer-reviewed, original human studies reporting serum cytokine levels in patients with HS. Reviews, meta-analyses, case reports, editorials, letters, in vitro and animal studies, conference abstracts without the full text available, non-serum studies, and thematically unrelated publications were excluded. Results: Database searches identified records in PubMed, Embase, Scopus, and Google Scholar, of which three PubMed studies met the inclusion criteria. Manual screening of reference lists and citations identified three additional eligible publications. Overall, six studies were included in the final qualitative synthesis. The included studies reported elevated serum levels of key inflammatory mediators, including IL-17A, IL-6, IL-1β, IL-23, IL-18, and soluble TNF receptors, in patients with HS compared to healthy controls. Several cytokines were associated with disease severity, and selected markers showed changes during biologic treatment. Stratification into immunological endotypes based on cytokine profiles and clinical features was also proposed. Conclusions: Pro-inflammatory cytokines, especially those involved in the IL-1β–IL-17 axis, show potential as biomarkers of disease severity and treatment response in HS. Their assessment may support future personalized therapeutic strategies. However, current evidence remains limited by small study numbers and methodological heterogeneity. Further large-scale prospective and longitudinal studies are required before serum cytokine profiling can be implemented in routine clinical practice.