Hidradenitis suppurativa (HS) is a serious skin disease that causes painful abscesses in the arm pits, groin, buttocks and anogenital region. HS affects approximately 1% of the population and is more common in females. Obesity and smoking are well-known risk factors promoting HS. HS is often associated with other autoimmune diseases. A hallmark of HS is the disintegration of terminal hair follicles surrounded by inflammatory cells. Although the underlying cause of HS is not fully understood, evidence suggests deviations of the immune system. Research has shown an imbalance of immune cells, with increased numbers of pro-inflammatory (inflammation-causing) Th17 cells compared to anti-inflammatory regulatory T cells (Tregs), which is called an increased Th17/Treg ratio. It was the aim of this study from the German Universities of Osnabrück and Munich to clarify whether obesity and smoking promote the Th17/Treg imbalance, which could be confirmed in their study. Notably, Tregs interact with hair follicle stem cells and thereby maintain hair follicle integrity, which is disturbed in HS. Furthermore, the investigators showed that other diseases that are associated with HS also have an increased Th17/Treg ratio, pointing to a common cause. Different drugs have beneficial effects in HS treatment. The authors wondered whether these drugs may normalize the increased Th17 cell numbers and/or enhance Treg cell numbers, which was supported by their study. The authors concluded that imbalances of Th17 and Treg cells is a feature of the immune system in HS, which can help guide future treatments.