181. Integrating clinical profiles and microRNAs to uncover molecular mechanisms in treatment-resistant schizophrenia

Abstract

Abstract Background Treatment-resistant schizophrenia (TRS), defined as the persistence of symptoms despite adequate antipsychotic treatment, remains frequently underrecognized, with clozapine, the gold standard, introduced only after an average delay of 4–9 years. In this study, we aimed to identify which Positive and Negative Syndrome Scale (PANSS) factors, executive function measures, and selected microRNAs (miRNAs) are most strongly associated with TRS, and to investigate the molecular underpinnings targeted by these miRNAs, thereby hypothesizing aberrant mechanisms contributing to the TRS condition. Aims & Objectives This study sought to (i) identify clinical (PANSS and executive function) and circulating miRNA features associated with TRS, (ii) integrate these features via machine learning to define a predictive signature, and (iii) investigate biological pathways regulated by TRS-related miRNAs to uncover mechanisms contributing to treatment resistance. Method We examined 60 patients with schizophrenia (25 treatment-responsive, 35 TRS) following a structured retrospective-prospective evaluation of antipsychotic response. Seventeen serum miRNAs were assessed. Principal Component Analysis (PCA) identified clinical variables and miRNAs with loading scores ≥ 0.4, which were used to train three machine learning models. Random Forest (RF) provided the best balance of accuracy, sensitivity, specificity, and generalizability. Based on RF with nested cross-validation, selected miRNAs underwent Gene Ontology (GO) and KEGG enrichment analyses with Benjamini–Hochberg correction. Results PCA highlighted PANSS emotional (EMO), disorganization (DIS), and excitement (EXC) factors, processing speed, and miRNAs (miR-132-3p, miR-181-5p, miR-203a-3p, miR-199a-5p, miR-128-3p). RF classified TRS patients based on higher EMO, DIS, EXC, miR-132-3p, miR-181-5p, and miR-203a-3p, with 62.9% sensitivity, 60% specificity, and 0.71 AUC. GO analysis indicated that miR-132, miR-181b, and miR-203a regulate stress response, apoptosis, cell cycle, differentiation, and protein homeostasis, converging on synaptic signaling and neuroplasticity pathways (ErbB, glutamatergic, dopaminergic ones). MiR-132 targets were enriched in processes related to stress response, nutrient sensing, and DNA damage signaling, with localization at the apicolateral membrane and functions in ubiquitin-ligase and kinase regulation, indicating a role in protein homeostasis and signaling modulation. MiR-181b targets were primarily associated with extrinsic apoptosis, negative regulation of cell growth, G1/S transition, and transcriptional repression, suggesting involvement in cell survival and proliferation control. MiR-203a targets showed enrichment in intrinsic apoptosis, neuronal apoptosis, oxidative-stress response, and differentiation pathways, including neuronal development, further implicating this miRNA in cell survival and neurodevelopmental processes. Enrichment analyses showed that the TRS-associated miRNAs converged on core schizophrenia-related pathways. miR-132 was strongly enriched in ErbB and glutamatergic signaling, while miR-181b and miR-203a showed robust enrichment in dopaminergic synapse and ErbB pathways, regulating key neuroplasticity and neurotransmission genes (e.g., MAPK, AKT, GRIN2, HOMER, COMT). These findings suggest that increased expression of these miRNAs may enhance gene silencing across synaptic and intracellular signaling cascades, potentially contributing to impaired neuroplasticity and treatment resistance through downregulation of critical neurotransmission-related targets. Predicted targets included key neurotransmission genes (DRD1, HOMER1, MAPK1/3, GRIN2A/D), also modulated by antipsychotics. Discussion & Conclusions TRS is characterized by a combined clinical-molecular signature involving PANSS domains, and selected miRNAs converging on synaptic and neuroplasticity networks. Dopaminergic, glutamatergic and ErbB pathways emerged as central hubs, suggesting that antipsychotic effects may be mediated, at least in part, through miRNA-driven mechanisms underlying TRS.