Trained Immunity and Its Potential Implications in the Etiopathogenesis of Hidradenitis Suppurativa: A New Paradigm in Chronic Inflammation?

Hidradenitis suppurativa (HS) is a chronic auto-inflammatory skin disorder characterised by recurrent, painful nodules, abscesses and tunnels, often leading to tissue destruction with a significant impairment in quality of life. Despite advancements in understanding, HS remains a complex disease, whose exact pathogenesis is yet to be revealed. Nevertheless, the role of a dysregulated innate immune response has been established, potentially contributing to the persistent and chronic inflammation. Recent advances in immunology have highlighted the concept of trained immunity, a form of innate immune memory that may provide new insights into HS pathophysiology. Trained immunity is mediated by epigenetic and metabolic reprogramming of innate immune cells, enabling them to mount a heightened and prolonged inflammatory response upon subsequent stimuli, even in the absence of the original trigger. We hypothesize that trained immunity could contribute to the persistent inflammatory state, influencing HS progression and severity. Environmental and microbial factors may act as persistent stimuli, leading to activation of innate immune pathways. From a mechanistic perspective, trained immunity in HS might involve increased cytokine production, altered myeloid cell differentiation and persistent epigenetic modifications favouring a pro-inflammatory phenotype. Identifying specific molecular markers associated with trained immunity in HS could provide new diagnostic and prognostic tools and may open novel therapeutic avenues. By exploring the potential role of trained immunity in HS, we provide a new perspective on chronic inflammation, thus hypothesizing another actor involved in the aetiology/pathogenesis of this complex disease.