Open Access

Carmen Schiweck, Mareike Aichholzer, Andreas Reif, Sharmili Edwin Thanarajah

• Highlights • Suicides which occurred in a biologics trial targeting the IL-17R are revisited. • High IL-17 levels are found in depression by the majority of reports. • Results from studies regarding IL-17 and psychosis are mixed. • Very few psychiatric studies investigated IL-17 signalling in suicidality. • Potential mechanisms how IL-17 influences neuro-inflammation are described. Abstract: Interleukin 17 (IL-17) is a potent pro-inflammatory cytokine which plays a role in autoimmune disorders, such as psoriasis and multiple sclerosis, and is important for the defense against pathogens, particularly in the gut. However, IL-17 has recently also gained attention in association with suicidal behavior. In this review, we review the literature regarding IL-17 in psychiatric disorders and suicidality. We also take a closer look at the suicides which occurred in the clinical trial for psoriasis with brodalumab, a monoclonal antibody targeting the IL-17 receptor. Lastly, we discuss potential working mechanisms relevant to neuroinflammation and the possible involvement of IL-17.