Activation of the coagulation and fibrinolysis system is a significant factor in secondary brain injury following spontaneous intracerebral haemorrhage (ICH). However, the relationships between plasma D-dimer, the smallest fibrinolysis-specific degradation product, and its implications for haematoma expansion (HE), in-hospital mortality, and coma at discharge in ICH patients have yet to be system-atically explored, highlighting the need for further research in this area.

In this study, we conducted a comprehensive assessment of plasma D-dimer levels in a sample consisting of 451 patients diagnosed with ICH and 114 healthy controls. Our approach included baseline measurements, such as haematoma volume, National Institutes of Health Stroke Scale (NIHSS) scores, and Glasgow Coma Scale (GCS) scores, to evaluate and quantify neurological deficits following ICH. Logistic regression analysis was used to determine the independent relationship between plasma D-dimer levels and clinical outcomes. To investigate the role of D-dimer in secondary brain injury, we analysed the changes in plasma D-dimer levels at admission and on days 3, 7, and 14 in the ICH with HE subgroup. Finally, we conducted a prognostic evaluation based on in-hospital mortality and the rate of coma at discharge.

The study revealed a marked increase in plasma D-dimer levels among patients with ICH compared with healthy controls (489.4 ± 1026 vs. 99.34 ± 55.09, p < 0.0001). This increase in plasma D-dimer levels strongly correlated with the severity of haemorrhage. Additionally, logistic regression analysis indicated that elevated plasma D-dimer levels were associated with poor clinical outcomes following ICH. Notably, plasma D-dimer levels within the HE subgroup significantly increased during the acute phase of ICH. Furthermore, both in-hospital mortality and the incidence of coma at discharge progressively increased with increasing D-dimer levels.

Elevated plasma D-dimer levels in patients with ICH significantly correlate with in-hospital mortality and the rate of coma at discharge. Notably, these levels markedly increase during the acute phase of the ICH with HE subgroup. These significant findings underscore the pivotal role of D-dimer as a biomarker in secondary brain injury following ICH and offer a novel predictive indicator for clinical outcomes associated with this condition.

To explore the mechanism of CORM-2 on attenuating hemorrhage-related inflammation.

Microglia were isolated from neonatal rats (1–2 days old) and identified using CD11b/c antibody. Subsequently, some of the microglia were co-cultured with red blood cells (RBCs) marked with PKH26 fluorescent dye, and then treated with CORM-2. Microglial cells were divided into three cultures: microglia, microglia+ ^PKH26+RBCs and microglia + ^PKH26+RBCs + CORM-2. Microglial phagocytosis of ^PKH26+RBCs was observed under an inverted fluorescence microscope and were determined by cell counting plates under microscopy. Moreover, the fluorescence intensity of microglia that phagocytized ^PKH26+RBCs was detected through immunofluorescence. The expression levels of HO-1, NF-κB p65, and IL-1β were detected using RT-qPCR, western blotting, and immunofluorescence, respectively. The levels of carbon monoxide hemoglobin (HbCO) in the cell supernatant in each group were measured using enzyme-linked immunoassay (ELISA).

After 1-day of co-culturing, the reduction in the number of residual ^PKH26+RBCs in the microglia+ ^PKH26+RBCs + CORM-2 group was significantly greater than that in the microglia+ ^PKH26+RBCs, which revealed that microglia phagocytosis was enhanced in CORM-2 treated group. Moreover, compared with microglia + ^PKH26+RBCs group, the microglia+ ^PKH26+RBCs + CORM-2 group showed higher levels of HO-1 mRNA and protein expression at day-3 and day-5 after co-culturing. Furthermore, CORM-2 significantly inhibited the expression of mRNA and proteins of NF-κB p65 and IL-1β after 3 days of co-culturing. Meanwhile, CORM-2 did not increase the level of HbCO in the cell supernatant.

CORM-2 inhibits RBCs-induced inflammation in vitro by promoting microglial phagocytosis of RBCs and decreases IL-1β and NF-κB p65; the mechanism may implicate the HO-1/CO system.

This study was supported by the National Science & Technology Fundamental Resource Investigation Program of China (2018FY100903 to XPY), and Jiangxi Provincial Health Commission Science and Technology Plan project(202311506 to ZYC), Jiangxi Provincial Administration of Traditional Chinese Medicine science and technology plan project (2022A322 to ZYC), Key Projects of Jiangxi Provincial Department of Education (GJJ2201902 to ZYC), Youth Foundation of Natural Science Foundation of Jiangxi Province (20224BAB216045 to ZYC).