Human urinary kallidinogenase may improve the prognosis of acute stroke patients with early neurological deterioration

Abstract Objectives Some acute ischemic stroke (AIS) patients still suffer from early neurological deterioration (END) after receiving intravenous thrombolysis (IVT), and these patients often have a poor prognosis. The purpose of our study is to observe the efficacy and safety of human urinary kallidinogenase (HUK) treatment in patients with END. Methods This was a retrospective analysis and 49 patients with END who met the inclusion criteria were divided into the observation group and the control group. All patients received routine treatment of AIS, while patients in the observation group were treated with HUK within 24 h after IVT and the other group without HUK. Results There were 24 patients in the observation group and 25 patients in the control group. After treatment, favorable prognosis (mRS scores ≤2) at 3 months in the observation group with 13 cases (54.17%) was significantly better than that in the control group with four cases (16%) (p = .001), and there was no statistical difference between the two groups in any hemorrhagic complication. Conclusion HUK is considered to be safe and may improve the prognosis of AIS patients with END after IVT. More clinical trials are needed to validate these results in the future.

The ARTIS trial (Antiplatelet Therapy in Combination With recombinant tissue plasminogen activator Thrombolysis in Ischemic Stroke) found that early application of intravenous aspirin in patients with AIS after IVT does not improve the clinical outcome at 3 months but increases the risk of symptomatic intracranial hemorrhage (sICH) (Zinkstok et al., 2010). Nevertheless, a study recently got a different conclusion that early antithrombotic therapy might be a feasible treatment to solve the dilemma (Tisserand et al., 2014). Then, a retrospective clinical research found that a low dose of tirofiban in patients with END within the first 24 h after IVT did not increase the risk of sICH, ICH as well as mortality, and seemed to be associated with neurological improvement at 3 months (C. Wu et al., 2019). On the whole, the fact that whether the usage of antiplatelet agents within the first 24 h after IVT increased the risk of sICH still needs to be validated. Meanwhile, a systematic review and meta-analysis recommended that a good collateral circulation was closely related to the favorable outcome, and it was suggested to develop therapeutic approaches to augment collateral perfusion as an adjunctive strategy for acute stroke treatment (Leng et al., 2016).
Human urinary kallidinogenase (HUK), a tissue kallikrein, was demonstrated to augment collateral perfusion in animal experiments and patients with AIS (L. Han et al., 2015;Miao et al., 2016). It was recommended by Chinese Guidelines to treat the patients with acute ischemic stroke in 2018 (Level II recommendation, Level B evidence) (Qian et al., 2019). Based on the appellate theory, clinicians try to apply HUK to the treatment of stroke patients who develop END after IVT.
The present study was conducted to observe the efficacy and safety of HUK in the treatment in the patients with END after IVT with tissuetype plasminogen activator (rt-PA) by retrospectively analyzing the basic data of AIS patients from three comprehensive stroke centers.

Exclusion criteria
The exclusion criteria were as follows: 1. consistent with contraindications for IVT; 2. the standard of rt-PA intravenous thrombolysis was met but the total dose of rt-PA was less than 0.9 mg/kg; 3. patients who took any anticoagulant drugs in 1 week before stroke onset; 4. NIHSS score of patients ≥25 points; 5. patients who met END but received endovascular treatment such as mechanical thrombectomy, stent implantation, and artery thrombolysis; 6. patients who met END but deteriorated due to sICH, malignant edema, early recurrent ischemic stroke, and the poststroke seizure.

Intravenous thrombolytic therapy
The applied dose of rt-PA is the standard dose (0.9 mg/kg). The maximum dose is not more than 90 mg. Initially, 10% of the total dose was given in the first phase, and the remaining dose was infused intravenously within 1 h.

Assessment method
Classification of stroke Stroke is classified according to the TOAST classification system (Adams et al., 1993), including large-artery atherosclerosis (L-type), small-artery atherosclerosis (S-type), cardiogenic cerebral embolism (C-type), other determined etiology (O-type), and undetermined causes (U-type).

Definition of END
END can be defined as an increase of ≥4 points in the baseline NIHSS score or an increase of more than 2 points in the NIHSS score over the same subcategory when it deteriorated within 24 h (C. Wu et al., 2019).

The efficacy outcomes
The efficacy outcomes of HUK are based on the mRS score at 3 months.
The prognosis of the patients with END is divided into poor (mRS score >2 or death) and favorable levels (mRS score ≤2).

Safety assessment
The safety outcomes included the incidence of sICH, ICH, and systemic hemorrhage and mortality at 3 months. sICH is defined according to ECASS III, in which the increase of 4 points in the patient's NIHSS score from baseline or a direct result of death is because of intracranial hemorrhage associated with worsening clinical symptoms (Yaghi et al., 2017 Mortality of 3 m 12 (24.49%) 2 (8.33%) 10 (40%) .01
developed END due to low perfusion caused by aortic dissection in subsequent examination after IVT, five cases received bridging treatment after deterioration, and one case took anticoagulant drugs in 7 days before admission. In the end, 49 patients with END treated with rt-PA met the criteria of this study (the inclusion process is shown in   Table 2).
The efficacy outcomes of HUK are based on the mRS score at 3 months (the distribution between groups is shown in Figure 2). At 3 months, the favorable prognosis of the observation group with 13 cases (54.17%) is higher than that of the control group with four cases (16%) (p = .001). Binary logistic regression analysis was used to analyze the influence of HUK on the prognosis of patients with END. The results of univariate and multivariate logistic regression analyses of the prognosis of patients with END are shown in Tables 3 and 4, respectively. The outcome of p-values and odds ratio (OR) before and after adjusting age, atrial fibrillation, high-density lipoprotein, and NIHSS scores on deterioration was .002 versus .024 and 0.10 versus 0.14, respectively, as shown in Table 4.

DISCUSSION
In present study, the incidence of END was 19.21%. Previous studies found that it is not uncommon for patients with ACI after IVT to develop END. In terms of incidence, a meta-analysis found that the rate of END after IVT was 11.0% globally and varied by region, with a TA B L E 3 Univariate logistic regression analysis of the prognosis of early neurological deterioration (END) patients

Variable p
Age ( Note: t1, the time from the onset of stroke to IVT; t2, the time from the end of IVT to the onset of deterioration; L-type, large-artery atherosclerosis; Stype, small-artery atherosclerosis; C-type, cardiogenic cerebral embolism; O-type, other determined etiology; U-type, undetermined causes. Abbreviations: AF, atrial fibrillation; BMI, body mass index; CHD, coronary heart disease; HCY, homocysteine; HDL, high-density lipoprotein; LDL, lowdensity cholesterol; NIHSS, National Institutes of Health Stroke Scale; SBP, systolic blood pressure; TC, total cholesterol; TG, triglyceride.
highest incidence of 15.9% in Asia, 11.8% in North America, and 7.6% in Europe (Hou et al., 2019). The incidence of END in present study was close to that in Asia in the meta-analysis.
In present study, it was found that use of HUK within the first 24 h after IVT improved the prognosis of patients with END significantly and did not increase the risk of sICH, ICH, and systemic bleeding. In fact, END has been paid more and more attention because of its unfavorable prognosis. Attempts to improve the outcome of patients with END have been ongoing for many years. Therapies such as usage of antiplatelet drugs tirofiban after IVT had been found to improve the outcome of patients with END (B. Liu, Zhang, et al., 2020) (Huang et al., 2020).
There is one innovation in our research. Most of the studies about the treatment of HUK were done on general patients with AIS, while our study's population was aimed at the special part of them, the ones with early neurological deterioration after intravenous thrombolysis.
Studies have shown that treatment with HUK can reduce the rate of disability of stroke patients (Dong et al., 2020;D. Han et al., 2018;D. Wu et al., 2017). In our study, 54.17% of patients with END treated with HUK recovered well. Although the sample size in our study is not large enough, however, considering the nature of our study is a registration one, the data were retrospectively collected and the findings of our research were derived from the real world. The findings are useful for clinicians to make decisions for AIS patients who received IVT to some extent.
Furthermore, in what way HUK improves the prognosis of END is an interesting question. First, it was found that HUK could activate the kalinase system, selectively dilate the microvessels in the ischemia regions, and promote the formation of revascularization in the ischemic area (L. Han et al., 2015). Second, HUK can selectively dilate infarcted blood vessels, increase blood flow of ischemic areas, and improve the nerve function of patients by improving microcirculation (Sun et al., 2016). Third, an animal experiment showed that HUK also had a certain function of anti-inflammation, anti-apoptosis, and promoting neurogenesis (L. Han et al., 2015). Among these mechanisms, Abbreviations: CI, confidence interval; OR, odds ratio. a After adjusting age, atrial fibrillation, high-density lipoprotein, and NIHSS score at deterioration. the "collateral circulation mechanism" is relatively recognized for now.
Cerebral collateral circulation varies greatly among individuals, and a good collateral circulation is often associated with a good long-term neurological function for stroke patients after receiving IVT . A Chinese study applying magnetic resonance perfusion imaging to examine patients with ACI treated with HUK for 12 days demonstrated that blood flow increased in ischemic area and was associated with prognosis improving, suggesting that HUK augmented collateral perfusion (J. Li, Chen, et al., 2015). Hence, we speculate that HUK may improve the prognosis of patients with END by promoting the formation of collateral circulation and enlarging collateral perfusion.
Our study has some limitations. First, it is a retrospective study with a small sample. Second, the collateral state of patients with END was not evaluated before and after the usage of HUK. As a result, how HUK improves the prognosis of patients with END remains unclear.

CONCLUSIONS
The present study suggests that HUK administration within the first 24 h after IVT with rt-PA may not increase the risk of sICH, ICH, and systemic bleeding, and it may improve the prognosis of the patients who developed early neurological deterioration, but that needs more large and prospective studies to prove.

ACKNOWLEDGMENTS
This study was supported by National Key R&D Program of China, No. 2018YFC1311300 and Science and Technology Plan Projects of Qingxiu District of Nanning, Guangxi Province, No. 2020043.

CONFLICT OF INTEREST
The authors declare no conflict of interest.

DATA AVAILABILITY STATEMENT
All data generated or analyzed during this study are included in this article.