This special issue, also pays particular attention to the role of proinflammatory Th17 T cells and T cell derived cytokines in autoimmune, cardiovascular, and infectious diseases (“Interleukin-17A Exacerbates Ferric Chloride-Induced Arterial Thrombosis in Rat Carotid Artery,” authored by F. Maione et al.; “Th17 Cells in Autoimmune and Infectious Diseases,” authored by J. F. Zambrano-Zaragoza et al.; “Limited Applicability of GW9662 to Elucidate PPARγ-Mediated Fatty Acid Effects in Primary Human T-Helper Cells,” authored by A. Jaudszus et al.). Here, IL17A is linked to infectious disease.