Understanding the mechanisms of treatment response in depression, focus on electro-convulsive therapy

Multiomics and blood-based biomarkers of electroconvulsive therapy in severe and treatment-resistant depression: study protocol of the DetECT study

Electroconvulsive therapy (ECT) is commonly used to treat treatment-resistant depression (TRD). However, our knowledge of the ECT-induced molecular mechanisms causing clinical improvement is limited. To address this issue, we developed the single-center, prospective observational DetECT study ("Multimodal Biomarkers of ECT in TRD"; registered 18/07/2022, www.clinicalTrials.gov , NCT05463562). Its objective is to identify molecular, psychological, socioeconomic, and clinical biomarkers of ECT response in TRD. We aim to recruit n = 134 patients in 3 years. Over the course of 12 biweekly ECT sessions (± 7 weeks), participant blood is collected before and 1 h after the first and seventh ECT and within 1 week after the twelfth session. In pilot subjects (first n = 10), additional blood draws are performed 3 and 6 h after the first ECT session to determine the optimal post-ECT blood draw interval. In blood samples, multiomic analyses are performed focusing on genotyping, epigenetics, RNA sequencing, neuron-derived exosomes, purines, and immunometabolics. To determine clinical response and side effects, participants are asked weekly to complete four standardized self-rating questionnaires on depressive and somatic symptoms. Additionally, clinician ratings are obtained three times (weeks 1, 4, and 7) within structured clinical interviews. Medical and sociodemographic data are extracted from patient records. The multimodal data collected are used to perform the conventional statistics as well as mixed linear modeling to identify clusters that link biobehavioural measures to ECT response. The DetECT study can provide important insight into the complex mechanisms of ECT in TRD and a step toward biologically informed and data-driven-based ECT biomarkers.

The P2X7 receptor in mood disorders: Emerging target in immunopsychiatry, from bench to bedside

Psychiatric disorders are among the most burdensome disorders worldwide. Though therapies have evolved over the last decades, treatment resistance still affects many patients. Recently, neuroimmune systems have been identified as important factors of mood disorder biology. The underlying dysregulation in neuroimmune cross-talk is driven by genetic risk factors and accumulating adverse environmental influences like chronic psychosocial stress. These result in a cluster of proinflammatory cytokines and quantitative and functional changes of immune cell populations (e.g., microglia, monocytes, T cells), varying by disease entity and state. Among the emerging immune targets, purinergic signalling revolving around the membranous and ATP specific P2X7 receptor (P2X7R) has gained wider attention and clinical studies making use of antagonistic drugs are on-going. Still, no clinically meaningful applications have been identified so far. A major problem is the often overly simplified approach taken to translate findings from bench to bedside. Therefore, the present review focuses on purinergic signalling via P2X7R in the context of recent advances in immunopsychiatric mood disorder research. Our aim is to provide an overview of the current P2X7R-related findings, from bench to bedside. First, we summarize the characteristics of purinergic signalling and P2X7R, followed by a depiction of genetic and clinical data connecting P2X7R to mood disorders. We close with our perspective on current developments and discuss changes necessary to translate the evident potential of P2X7R signalling modulation into meaningful clinical application. This article is part of the Special Issue on 'Purinergic Signaling: 50 years'.

P2X7 Receptor-Related Genetic Mouse Models – Tools for Translational Research in Psychiatry

Depression is a common psychiatric disorder and the leading cause of disability worldwide. Although treatments are available, only about 60% of treated patients experience a significant improvement in disease symptoms. Numerous clinical and rodent studies have identified the purinergic P2X7 receptor (P2X7R) as one of the genetic factors potentially contributing to the disease risk. In this respect, genetically engineered mouse models targeting the P2X7R have become increasingly important in studying designated immunological features and subtypes of depression in vivo. This review provides an overview of the P2X7R -related mouse lines currently available for translational psychiatric research and discusses their strengths, weaknesses, and potentials.