Cerebrospinal fluid platelet-derived growth factor receptor-beta is negatively correlated with depressive symptom severity in suicide attempters

• Low CSF PDGFR-β levels are associated with more severe depressive symptoms in suicide attempters. • PDGFR-β may indicate depression severity, independent of blood-brain barrier integrity. • Blood-brain barrier dysfunction may play a role in suicidality and depression. Depression and suicidal behavior have been linked to increased blood-brain barrier (BBB) permeability. Platelet-derived growth factor receptor beta (PDGFR-β) is widely expressed in pericytes and promotes BBB integrity. Here, we investigated cerebrospinal fluid (CSF) levels of PDGFR-β in suicide attempters and healthy controls and correlated PDGFR-β to depression symptom severity. We measured levels of PDGFR-β in CSF from recent suicide attempters using electrochemiluminescence immunoassays. PDGFR-β was correlated to CSF/serum albumin ratio (Qalb), an established BBB integrity biomarker, and symptom severity according to the Montgomery-Åsberg Depression Rating Scale (MADRS). There was a significant negative correlation between PDGFR-β and total MADRS score in suicide attempters ( r =-0.47, p = 0.003, n = 38). PDGFR-β did not correlate significantly with Qalb ( r = 0.179, p = 0.268, n = 40). Although PDGFR-β levels may not reflect BBB integrity, low CSF levels of this biomarker were associated with more severe depressive symptoms. We hypothesize that this may be due to mechanisms unrelated to BBB integrity including the effects of PDGFR-β on neurogenesis and cellular proliferation.