GENERAL ASPECTS OF HIDRADENITIS SUPPURATIVA (HS): AN INFLAMMATORY, NON-INFECTIOUS DISEASE: THE SECONDARY ROLE OF INFECTIONS

Hidradenitis suppurativa (HS) is a severe, chronic inflammatory disease of the hair follicle, with a significant impairment of patients’ quality of life. The pathogenesis of HS is complex and multifactorial, involving both host-related and environmental factors, such as cigarette smoking, follicular trauma and skin-resident bacteria. The pathogenetic role of bacteria has been long suspected, due to the clinical signs of suppuration and the clinical benefit of topical and systemic antibiotics. Recent studies have characterized the spectrum of bacteria isolated from lesional skin during the various stages of disease progression. Culture-independent and morphological studies have shown new microbiological aspects of HS, such as biofilm formation and an altered composition of the bacterial microbiome in affected skin, which is defined as dysbiosis. The concept of bacterial dysbiosis interacting with abnormal innate immune responses of epithelial surfaces is common to Crohn’s disease and HS. We reviewed the role of bacterial infection and dysbiosis in the pathogenesis of HS, which allegedly is caused by an intrinsic, deregulated innate immune response of hair follicle keratinocytes.