Temporal immune effects of Oral ketamine on PTSD: Transcriptomic evidence of short-term inflammation suppression and sustained immune Remodelling.

Ketamine provides rapid acting symptom relief, making it a promising intervention for post-traumatic stress disorder (PTSD). However, the mechanisms driving its long-term efficacy over weeks and months remain poorly understood. This study investigated the short- and sustained impacts on gene expression of an open-label six-week subanesthetic oral ketamine trial in 23 PTSD participants (9 males, 14 females). Peripheral blood mononuclear cells (PBMCs) were collected at baseline, one week (short-term), and four weeks (sustained) post ketamine treatment for RNA sequencing and transcriptome analysis. Differential expression analysis identified substantial and persistent transcriptomic changes over time, with 533 genes upregulated and 621 downregulated across timepoints. Notably, there was a 37% increase in differential gene expression between the short- and sustained responses, accompanied by a 6.5-fold rise in expression magnitude and an 8.8-fold enhancement in pathway activity. Pathway analysis emphasised important immune and inflammatory pathways that appear to be modulated by ketamine, including interferon alpha/beta signalling (z = 4), IL-17 signalling pathway (z = 3.36), and cytokine storm signalling (z = 4.26) and neutrophil degranulation (z = 6.0) which differed across timepoints. The findings suggest a transition from short-term inflammation suppression to sustained immune regulation. Changes in key cytokines, chemokines, interferons and antimicrobial peptides included, IL-6, IL-1β, IFI27, IL-10 signalling, CXCL8, SOCS1/3 and CAMP which represent central regulators of immune and inflammatory pathways. These molecular changes offer novel insights into the sustained therapeutic potential of ketamine for PTSD and highlight avenues for precision psychiatry and maintenance therapy to prevent relapse.