Expressions of Eotaxin-3, Interleukin-5, and Eosinophil-Derived Neurotoxin in Chronic Subdural Hematoma Fluids

Preoperative elevated eosinophils in peripheral blood for prediction of postoperative recurrence of chronic subdural hematoma

OBJECTIVE

Chronic subdural hematoma (CSDH) is a common neurological disease with a significant postoperative recurrence rate. There are numerous reported studies of the development of CSDH. In recent years, fibrinolysis, angiogenesis, and inflammation have all been identified as relevant factors in the development of CSDH. While several authors have reported risk factors associated with CSDH recurrence, differential blood count of leukocytes has not yet been discussed. Therefore, in this study the authors aimed to retrospectively investigate the association between differential blood leukocyte count and the rate of CSDH recurrence.

METHODS

The authors retrospectively reviewed 476 patients with 529 CSDHs who underwent surgery at a single institution between January 2011 and December 2021. After exclusion of patients who had not undergone a differential blood test of leukocytes preoperatively, CSDHs in 517 cerebral hemispheres of 466 patients were included in the study. Peripheral blood eosinophil counts ≥ 100/µL were considered eosinophil rich.

RESULTS

CSDHs in 494 cerebral hemispheres of 445 patients were followed up postoperatively for at least 3 months or until resolution indicated by CSDH disappearance. Postoperative recurrence of CSDH was observed in 46 cerebral hemispheres (9.3%). Among the preoperative differential blood counts of all leukocytes, eosinophils alone were significantly associated with CSDH recurrence (median [IQR] 76/µL [30-155/µL] vs 119/µL [39-217/µL]; p = 0.03). Multivariable regression analysis showed thrombocytopenia (adjusted OR [aOR] 5.23, 95% CI 1.85-14.79; p = 0.002), use of anticoagulant drugs (aOR 2.51, 95% CI 1.17-5.38; p = 0.02), hematoma volume (10 mL per increase) (aOR 1.08, 95% CI 1.00-1.16; p = 0.04), and eosinophil-rich peripheral blood (aOR 2.22, 95% CI 1.17-4.23; p = 0.02) were all independent predictors for CSDH recurrence.

CONCLUSIONS

This study showed that preoperative peripheral blood eosinophil count was an independent risk factor for CSDH recurrence. Therefore, patients with CSDH who have elevated eosinophils preoperatively in peripheral blood require careful follow-up.

Pilot Biomarker Analysis and Decision Tree Algorithm Modeling of Patients with Chronic Subdural Hematomas

The elderly population are at high risk for developing chronic subdural hematoma (cSDH). Surgical evacuation of cSDH is one of the most common procedures performed in neurosurgery. The present study aims to identify potential inflammatory biomarkers associated with its development and recurrence. Patients (>65 years of age) who presented with symptomatic cSDH (≥1 cm thickness or ≥5 mm midline shift [MLS]), requiring surgical intervention, were prospectively enrolled. The collected cSDH fluid was analyzed for inflammatory markers. Computed tomography (CT) scan data included pre-operative cSDH thickness and MLS. Outcome data included Glasgow Outcome Scale-Extended (GOS-E) score at 3, 6, and 12 months post-surgery, as well as cSDH recurrence. A decision tree model was used to determine the predictive power of extracted analytes for MLS, cSDH thickness, and recurrence. This pilot study includes 20 enrolled patients (mean age 77.9 ± 7.4 years and 85% falls). Rate of cSDH recurrence was 42%, with 21% requiring reoperation. Chemokine (C-X-C motif) ligand 9 (CXCL9) concentrations correlated with cSDH thickness (r = 0.975, p = 0.040). Interleukin (IL)-6 and vascular endothelial growth factor (VEGF)-A concentrations correlated with MLS (r = 0.974, p = 0.005; r = 0.472, p = 0.036, respectively). IL-5 concentrations correlated with more favorable GOS-E scores at 3, 6, and 12 months (r = 0.639, p = 0.006; r = 0.727, p = 0.003; r = 0.693, p = 0.026, respectively). Regulated on activation, normal T-cell expressed and secreted (RANTES) concentrations correlated with complete cSDH resolution (r = 0.514, p = 0.021). The decision tree model identified that higher concentrations of CXCL9 were predictive of MLS (risk ratio [RR] = 12.0), higher concentrations of IL-5 were predictive of cSDH thickness (RR = 4.5), and lower concentrations of RANTES were predictive of cSDH recurrence (RR = 2.2). CXCL9, IL-6, VEGF, IL-5, and RANTES are associated with recurrence after surgery and may be potential biomarkers for predicting cSDH recurrence and neurological outcomes.

The Enigma of Eosinophil Degranulation

Eosinophils are specialized white blood cells, which are involved in the pathology of diverse allergic and nonallergic inflammatory diseases. Eosinophils are traditionally known as cytotoxic effector cells but have been suggested to additionally play a role in immunomodulation and maintenance of homeostasis. The exact role of these granule-containing leukocytes in health and diseases is still a matter of debate. Degranulation is one of the key effector functions of eosinophils in response to diverse stimuli. The different degranulation patterns occurring in eosinophils (piecemeal degranulation, exocytosis and cytolysis) have been extensively studied in the last few years. However, the exact mechanism of the diverse degranulation types remains unknown and is still under investigation. In this review, we focus on recent findings and highlight the diversity of stimulation and methods used to evaluate eosinophil degranulation.

Sequential Expression of Chemokines in Chronic Subdural Hematoma Fluids after Trepanation Surgery

Chronic subdural hematoma (CSDH) is considered an angiogenic and inflammatory disease. Chemokines attract leukocytes, and invading neutrophils and monocytes/macrophages play important roles in wound healing. However, no studies have been reported regarding changes in expression of chemokines in CSDH fluid after trepanation surgery. We randomly divided patients who underwent trepanation surgery into two groups. One was the irrigation group, in which irrigation of CSDH fluids was performed and a drainage tube was placed (n = 10). The other was the non-irrigation group, in which a drainage tube was inserted without irrigation (n = 10). CSDH fluids were collected during the trepanation surgery, immediately after surgery and on day 1 through the drainage tube. The concentrations of interleukin-8 (IL-8), growth-regulated oncogene-α (GRO-α), epithelial neutrophil-activating peptide 78 (ENA-78), monocyte chemoattractant protein-1 (MCP-1), interferon-γ-induced protein-10 (IP-10), tissue plasminogen activator (tPA), von Willebrand factor (vWF), eotaxin-3, and myeloperoxidase (MPO) in each CSDH fluid sample were measured using enzyme-linked immunosorbent assay kits. After irrigation, concentrations of all chemokines decreased. However, concentrations of IL-8, GRO-α, ENA-78, MCP-1, and MPO were significantly increased on day 1 compared with concentrations during surgery with or without irrigation. In contrast, there were no changes in concentrations of IP-10, eotaxin-3, tPA, or vWF after trepanation surgery. Moreover, there were significant relationships among concentrations of IL-8, GRO-α, ENA-78, and MCP-1 during the surgery and on day 1. In CSDH fluids, chemokines that attract neutrophils, such as IL-8, GRO-α, ENA-78, and macrophage-attracting MCP-1, appear first after trepanation surgery, whereas lymphocyte-attracting IP-10 and eosinophil-attracting eotaxin-3 levels do not change within 1 day of surgery. These findings suggest that neutrophils and macrophages may play important roles in the healing process of CSDH at an early stage.

Assessment of peripheral blood cell inflammatory markers in patients with chronic subdural hematoma

OBJECTIVES

We aimed to study the role of peripheral blood cell inflammatory markers in patients with chronic subdural hematoma (CSDH).

PATIENTS AND METHODS

We enrolled 466 patients with CSDH and 150 healthy controls and retrospectively analyzed peripheral blood cell inflammatory markers, including neutrophils, platelets, lymphocytes, neutrophil/lymphocyte ratio (NLR), and platelet/lymphocyte ratio (PLR). Subsequently, we performed a subgroup analysis of the patients with CSDH based on gender, age, trauma history, and unilateral or bilateral hematoma.

RESULTS

The CSDH group had higher numbers of neutrophils and platelets, as well as a higher NLR and PLR, than those in the healthy control group. Further, compared with the healthy control group, the CSDH group had lower lymphocyte counts. Subgroup analysis indicated trauma history as the only significant factor.

CONCLUSION

Peripheral blood cell inflammatory markers could serve as indexes for evaluating the inflammatory state in patients with CSDH. There is a need for further studies on the prognostic role of this index in patients with CSDH.

Subdural haematomas drain into the extracranial lymphatic system through the meningeal lymphatic vessels

Subdural haematomas (SDHs) are characterized by rapidly or gradually accumulated haematomas between the arachnoid and dura mater. The mechanism of haematoma clearance has not been clearly elucidated until now. The meningeal lymphatic vessel (mLV) drainage pathway is a novel system that takes part in the clearance of waste products in the central nervous system (CNS). This study aimed to explore the roles of the mLV drainage pathway in SDH clearance and its impacting factors. We injected FITC-500D, A488-fibrinogen and autologous blood into the subdural space of mice/rats and found that these substances drained into deep cervical lymph nodes (dCLNs). FITC-500D was also observed in the lymphatic vessels (LYVE+) of the meninges and the dCLNs in mice. The SDH clearance rate in SDH rats that received deep cervical lymph vessel (dCLV) ligation surgery was significantly lower than that in the control group, as evaluated by haemoglobin quantification and MRI scanning. The drainage rate of mLVs was significantly slower after the SDH model was established, and the expression of lymphangiogenesis-related proteins, including LYVE1, FOXC2 and VEGF-C, in meninges was downregulated. In summary, our findings proved that SDH was absorbed through the mLV drainage pathway and that haematomas could inhibit the function of mLVs.