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A lower admission level of interleukin-6 is associated with first-pass effect in ischemic stroke patients
  1. Laura Mechtouff1,2,
  2. Thomas Bochaton2,3,
  3. Alexandre Paccalet2,
  4. Claire Crola Da Silva2,
  5. Marielle Buisson4,
  6. Camille Amaz4,
  7. Laurent Derex1,
  8. Elodie Ong1,2,
  9. Yves Berthezene5,6,
  10. Nathalie Dufay7,
  11. Michel Ovize2,4,
  12. Nathan Mewton2,4,
  13. Tae-Hee Cho1,2,
  14. Norbert Nighoghossian1,2,
  15. Omer F Eker5
  1. 1 Stroke Department, Hospices Civils de Lyon, Lyon, France
  2. 2 CarMeN Laboratory, INSERM U1060, University Lyon 1, Lyon, France
  3. 3 Cardiac Intensive Care Unit, Hospices Civils de Lyon, Lyon, France
  4. 4 Clinical Investigation Center, INSERM 1407, Hospices Civils de Lyon, Lyon, France
  5. 5 Neuroradiology Department, Hospices Civils de Lyon, Lyon, France
  6. 6 CREATIS, CNRS UMR 5220, INSERM U1044, University Lyon 1, Lyon, France
  7. 7 NeuroBioTec, CRB, Hospices Civils de Lyon, Lyon, France
  1. Correspondence to Dr Laura Mechtouff, Stroke Department, Hospices Civils de Lyon, Lyon 69002, France; laura.mechtouff{at}chu-lyon.fr

Abstract

Background First-pass effect (FPE) defined as a complete or near-complete reperfusion achieved after a single thrombectomy pass is predictive of favorable outcome in acute ischemic stroke (AIS) patients. We aimed to assess whether admission levels of inflammatory markers are associated with FPE.

Methods HIBISCUS-STROKE (CoHort of Patients to Identify Biological and Imaging markerS of CardiovascUlar Outcomes in Stroke) includes AIS patients with large vessel occlusion treated with mechanical thrombectomy following brain MRI. C-reactive protein, interleukin (IL)-6, IL-8, IL-10, monocyte chemoattractant protein-1, soluble tumor necrosis factor receptor I, soluble form suppression of tumorigenicity 2, matrix metalloproteinase-9 (MMP-9), soluble P-selectin, and vascular cellular adhesion molecule-1 were measured in admission sera using an ELISA assay. FPE was defined as a complete or near-complete reperfusion (thrombolysis in cerebral infarction scale (TICI) 2c or 3) after the first pass. A multivariate logistic regression analysis was performed to assess independent factors associated with FPE.

Results A total of 151 patients were included. Among them, 43 (28.5%) patients had FPE. FPE was associated with low admission levels of IL-6, MMP-9, and platelet count, an older age, lack of hypertension, lack of tandem occlusion, a shorter thrombus length, and a reduced procedural time. Following multivariate analysis, a low admission level of IL-6 was associated with FPE (OR 0.66, 95% CI 0.46 to 0.94). Optimal cut-off of IL-6 level for distinguishing FPE from non-FPE was 3.0 pg/mL (sensitivity 92.3%, specificity 42.3%).

Conclusion A lower admission level of IL-6 is associated with FPE.

  • stroke
  • thrombectomy
  • inflammatory response

Data availability statement

Data are available upon reasonable request. Further anonymized data can be made available to qualified investigators on request to the corresponding author.

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Introduction

The first-pass effect (FPE) defined as a complete or near-complete reperfusion achieved after the first thrombectomy pass predicts favorable outcome in acute ischemic stroke (AIS) patients, conversely poor outcome increases with multiple passes.1–6 There is growing interest in studying factors that indicate thrombus resistance to reperfusion through mechanical or pharmacological approaches. The composition and structural characteristics of thrombus, as its content in fibrin, von Willebrand factor, inflammatory cells and their byproducts, may account for thrombus resistance.7–9 Early changes in blood markers and cell counts have been reported in patients treated with mechanical thrombectomy (MT) but identifying those that may help to predict FPE remains a challenging issue as it may guide individualized therapeutic approaches.10 11

We aimed to evaluate whether admission levels of circulating inflammatory markers are associated with FPE in AIS patients.

Methods

Study population

The design and methods of the HIBISCUS-STROKE (CoHort of Patients to Identify Biological and Imaging markerS of CardiovascUlar Outcomes in Stroke), an ongoing cohort study, have been published elsewhere.12 Briefly, all patients admitted since October 2016 to the Lyon Stroke Center for an AIS with large vessel occlusion (LVO) treated with MT following brain magnetic resonance imaging (MRI) assessment. Patients with early reperfusion before MT or with target occlusion not reached owing to catheterization failure were excluded as well as patients with known inflammatory disease, active malignancy, vasculitis, antibiotics at admission, myocardial infarction, or major surgery in the 30 previous days were excluded in order not to skew the results of the biomarkers analysis. Baseline data on demographic characteristics, risk factors, and medical history were collected on admission. Stroke subtype was classified according to the Trial of Org 10 172 in Acute Stroke Treatment (TOAST) criteria. Neurological status was assessed by board-certified neurologists using National Institute of Health Stroke Scale (NIHSS) score at admission. Peripheral blood samples were collected from each patient at admission before intravenous thrombolysis administration.

Blood sampling protocol

Sera were prepared and stored at −80°C within 3 hours of collection at the NeuroBioTec biobank (CRB-HCL: BB-0033–00046, France). All samples were thawed only once for study measurements. Interleukin (IL)-6, IL-8, and IL-10 were measured using an enzyme-linked immunosorbent assay (ELISA) kit (Affymetrix, eBioscience). Monocyte chemoattractant protein-1 (MCP-1), soluble tumor necrosis factor receptor I (sTNF-RI), soluble form suppression of tumorigenicity 2 (sST2), matrix metalloproteinase-9 (MMP-9), soluble P-selectin, and vascular cellular adhesion molecule-1 (VCAM-1)were measured using R&D systems ELISA Kit (R&D Systems, Minneapolis, MN, USA). High-sensitivity C-reactive protein (hsCRP) and complete blood count were routinely measured at admission.

Endovascular procedure and neuroimaging

All MRIs were performed with 1.5-Tesla Intera or 3-Tesla Achieva scanners (Philips, Best, Netherlands). The admission MRI protocol included fluid-attenuated inversion recovery (FLAIR), T2-gradient echo, diffusion-weighted imaging (DWI), time-of-flight magnetic resonance angiography (MRA), and perfusion-weighted imaging. A radiologist blinded to the clinical and biological data independently reviewed the digital subtraction angiography (DSA) and MRI using a dedicated post-processing work station (3D slicer software). Baseline Alberta Stroke Program Early CT score (ASPECTS) and lesion volume on DWI were measured. Thrombus length was measured using the susceptibility vessel sign on T2* imaging. All endovascular procedures were performed under a dedicated neuroanesthesic protocol that encompassed conscious sedation or general anesthesia. The method of MT (stent retriever, contact aspiration, or both) was left to the discretion of the interventional neuroradiologist. Pre-treatment collateral status on DSA was categorized into poor (Higashida score 0–2) and good (Higashida score 3–4).13 FPE was defined as achievement of complete or near-complete reperfusion (thrombolysis in cerebral infarction scale (TICI) 2c or 3) after the first thrombectomy pass.

Statistical analysis

Continuous variables are expressed as means (SD) or medians (IQR) and categorical variables as absolute number (percentages). Fisher’s exact test was used to analyze categorical variables and the Mann–Whitney U test for continuous variables. Optimal cut-off levels of circulating inflammatory biomarkers for distinguishing FPE from non-FPE were identified using the Youden index. Univariate and multivariate logistic regression using a backward selection procedure were performed to assess independent factors associated with FPE. Covariates identified as statistically significant in univariate analyses (P<0.05) and hypothesized as causal along with other potential predictors independent of their univariate P value, selected a priori (age, occlusion site, ASPECTS, collateral circulation, intravenous recombinant tissue plasminogen activator, first-line thrombectomy technique, use of balloon guide catheter, and time from onset to groin puncture) were entered in multivariable logistic regression modeling.1 5 14–16 Two-tailed P<0.05 was considered to be statistically significant. The data were analyzed with Stata Version 15 (StataCorp, College Station, TX, USA).

Results

Study population

A total of 643 consecutive AIS patients were treated with MT in our institution from October 2016 to April 2019. Among them, 138 patients with computed tomography at admission, 46 with posterior circulation stroke, 241 without scheduled follow-up visit in our stroke center (secondary transfers from primary stroke center), 34 without informed consent, and nine without available blood samples were excluded. Of the remaining 175 patients included in the HIBISCUS-STROKE cohort, 11 with active disease resulting in systemic inflammation and 13 with early reperfusion before MT or with target occlusion not reached owing to catheterization failure were excluded. A total of 151 patients were included (figure 1). Mean age was 69±15 years. Median NIHSS on admission was 15.10–19 Forty-three (28.5%) patients had FPE. The main clinical and imaging characteristics are shown in table 1.

Figure 1

Flow chart of patient selection.

Table 1

Main clinical, imaging, and procedural characteristics of the study population according to the achievement of first-pass effect

Excluded patients

Excluded patients were older (72±15 vs 69±15 years; P=0.02), were more often female (264 (53.7%) vs 59 (39.1%); P<0.01), had a higher NIHSS score (17 (11–21) vs 15 (10–19)); P=0.03), and had less often a M1 middle cerebral artery segment occlusion (361 (73.4%) vs 124 (84.2%); P=0.03).

Factors associated with FPE

FPE was associated with lower admission levels of IL-6, MMP-9, and platelet count, an older age, lack of hypertension, lack of cervical ICA occlusion, and a shorter procedural time (figure 2, table 1, (). Admission levels of other circulating inflammatory markers were not associated with FPE online supplemental file 1. After adjustment for the main confounding factors, a lower admission level of IL-6 was associated with FPE (table 2). Optimal cut-off of admission level of IL-6 for distinguishing FPE from non-FPE was 3.0 pg/mL (sensitivity 92.3%, specificity 42.3%) .

Table 2

Circulating inflammatory markers associated with first-pass effect in univariate and multivariate analyses

Figure 2

Admission levels of circulating inflammatory markers according to first-pass effect (FPE). *Indicates P<0.05. IL-6, interleukin-6; MMP-9, matrix metalloproteinase-9.

Discussion

Various factors including retrieval technique, occluded vessel type, and especially clot characteristics may contribute to procedural success of MT in AIS patients.1 5 8 9 14 15 17–20 The relationship between circulating blood markers and FPE remains poorly documented. In the present study we found that a lower admission level of IL-6 was associated with FPE. Clinical norm ranges are unknown but optimal cut-off of admission level of IL-6 for distinguishing FPE from non-FPE was 3.0 pg/mL.21

The mechanism behind this relationship may lie in the overlap of inflammation and coagulation processes. Pro-inflammatory cytokines are released early in brain ischemia, especially IL-6.12 22 IL-6 is known to upregulate tissue factor expression and thrombin generation in sepsis and endotoxemia.23 The enzymatic cascade results in the formation of abnormally dense fibrin networks and changes in the viscoelastic properties and stability of clots.24 25 Thrombin also promotes platelet activation and further sustains inflammatory process via proteinase-activated receptors by inducing release of pro-inflammatory cytokines, including IL-6.26 27

In addition, neutrophil extracellular traps (NETs), a key mediator between innate immunity, inflammation, and hemostasis, may partly explain the relationship between IL-6 level and FPE. IL-6 seems to act as a driver of NETs formation, although it has not been specifically reported in stroke.28 29 These networks of DNA decorated with histones and granular proteins have been recognized as major triggers and structural factors of thrombosis.30–32 They contribute to the scaffold of thrombi irrespectively of their origin. This architecture may support the resistance to mechanical and enzymatic destruction.31 Indeed, a strong correlation has been observed between thrombus NETs content and the number of passes in AIS with LVO.9

It has also previously been observed that a sustained rise in IL-6 was associated with futile reperfusion in the setting of MT.12 Overall, we may hypothesize that the pivotal role of IL-6 in thromboinflammation impacts procedural process of MT and subsequent FPE rate while promoting concomitant microcirculation impairment supporting the no-reflow phenomenon.33 34 This may account for the reported relationship between IL-6 levels and stroke severity and outcome.35

The reason why levels of other circulating inflammatory markers were not associated with FPE is uncertain but may reflect the differential dynamic and role of these markers in the inflammatory process.

Our study has several limitations inherent in its single-site design and its small sample size. In addition, we cannot formally rule out that this observation could result from a type 1 error that would limit our interpretation. Moreover, in this observational study, the first-line MT method was left to the discretion of the interventional neuroradiologist and was subsequently heterogeneous. A future evaluation based on a common method to overcome this potential bias would be necessary to clarify the real impact of IL-6 level on FPE.

A further approach based on a coupled analysis of circulating markers of inflammation and thrombus composition may provide additional insight to understand the true role of IL-6 in FPE and could pave the way to specific therapy such as antibodies targeting IL-6 or combined strategies directed against NETs.9 31 32 36

Conclusion

In the present study we found that a lower admission level of IL-6 is associated with FPE.

Data availability statement

Data are available upon reasonable request. Further anonymized data can be made available to qualified investigators on request to the corresponding author.

Ethics statements

Patient consent for publication

Ethics approval

This research was conducted according to the ethical standards issued by the Declaration of Helsinki. The study was approved by the local ethics committee (IRB number 00009118).

Acknowledgments

Human biological samples and associated data were obtained from NeuroBioTec (CRB HCL, Lyon, France, Biobank BB-0033–00046).

References

Footnotes

  • Twitter @BochatonThomas, @alexPaccalet

  • NN and OFE contributed equally.

  • Contributors Study design: LM, MO, NN, OFE. Acquisition, analysis, or interpretation of data: all authors. Drafting the manuscript: LM, NN, OFE. Revising the manuscript critically for important intellectual content: TB, AP, CCDS, MB, CA, LD, EO, YB, ND, MO, NM, T-HC. Statistical analysis: LM, CA. Supervision: NN, OFE. Final approval of the version and agreement to be accountable for all aspects of the work: all authors.

  • Funding This work was supported by the RHU MARVELOUS (ANR-16-RHUS-0009) of Université Claude Bernard Lyon-1 (UCBL), within the program “Investissements d'Avenir” operated by the French National Research Agency (ANR) and the CASDEN prize from CASDEN/Fondation de l’Avenir awarded to Laura Mechtouff.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.