Introduction: Intracerebral hemorrhage (ICH) is the most lethal stroke subtype, largely due to secondary brain injury. Inflammation via the IL-6/JAK2/STAT3 pathway and iron toxicity from hemoglobin breakdown are known contributors to poor outcomes after ICH. However, expression of IL-6 pathway and iron-handling genes locally within the hematoma and systemically remains poorly defined. Using bulk RNA sequencing of hematoma and paired peripheral blood samples from patients undergoing minimally invasive ICH evacuation, we aimed to characterize the local and systemic expression of relevant genes and their relationships to ICH severity and systemic inflammation. Methods: We prospectively enrolled 12 patients with spontaneous ICH. Intraoperative hematoma and peripheral blood samples were collected and processed for RNA extraction, cDNA library preparation, and sequencing. Analysis focused on 50 genes involved in IL-6 signaling and iron metabolism. Linear regression models measured associations between gene expression and ICH severity (via ICH score), ICH location (deep vs lobar), and systemic laboratory markers of inflammation. Subgroup analyses separately examined hematoma, blood, and paired samples. Results: We analyzed 20 samples: 11 blood, 9 hematoma, and 8 paired. Multiple IL-6 pathways (JAK1, JAK2, STAT3, STAT5A/B, SOCS3) and iron-handling (HMOX2, SLC40A1, BLVRA) genes were significantly associated with greater ICH severity. Many of these associations persisted in compartment-specific analyses. In blood, EPOR expression correlated with neutrophil count and inversely with lymphocyte count, whereas EPO showed the opposite pattern. Paired analyses revealed higher EPOR expression in hematoma relative to blood in patients with elevated neutrophils. Several IL-6 genes (JAK1, JAK2, STAT3, STAT5A, TYK2, IL6R) inversely correlated with peripheral white blood cell counts in hematoma-to-blood ratios, suggesting compartmental differences in activation. Conclusion: This pilot study identifies distinct compartment-specific expression patterns linking IL-6 pathway activity, iron metabolism, and EPO/EPOR signaling with ICH severity and systemic inflammation. Hematoma and blood samples demonstrate overlapping yet divergent molecular-clinical relationships. Future work integrating single-cell transcriptomics, proteomics, and clinical outcomes will be critical to define cellular sources and therapeutic targets within inflammatory cascades driving secondary brain injury.
Eberle et al. (Thu,) studied this question.