Human urinary kallindinogenase therapy for acute ischemic stroke according to Chinese ischemic stroke subclassification: Clinical efficacy and risk factors

Abstract Introduction To evaluate effectiveness of human urinary kallindinogenase (HUK) in patients with acute ischemic stroke (AIS) according to Chinese ischemic stroke subclassification (CISS) and analyzed risk factors of clinical efficacy. Methods In this retrospective study, 134 patients received conventional therapy were enrolled to control group, and 132 patients received HUK treatment were enrolled to HUK group. National Institute of Health Stroke Scale (NIHSS) score was used to evaluate the clinical efficacy. Multivariate analysis of risk factors was performed by using logistic regression. Results After treatment, NIHSS score of HUK group was significant lower than that of control group (p = .009). Effectiveness rate was 71.2% in HUK group, and 53.7% in control group, respectively (p = .003). The NIHSS of patients with large artery atherosclerosis (LAA) subtype in HUK group was significantly lower than that in control group (p = .005). The absence of HUK (OR = 2.75), homocysteine (OR = 0.15), and CS subtype (OR = 0.18) were risk factors for HUK clinical efficacy. Conclusions Human urinary kallindinogenase is an effective therapeutic approach for treatment of patients with AIS, especially in patients with LAA subtype. The absence of HUK, elevated homocysteine, and cardiogenic stroke subtype were risk factor for clinical efficacy of HUK.

patients (Cornejo-Juarez et al., 2015;Rabinstein, 2017); however, conventional treatment is dissatisfactory. Intravenous thrombolysis with recombinant tissue type plasminogen activator (rtPA) was the most effective treatment for AIS (NBCMA, 2015). However, the treatment usually resulted in an increased risk of intracranial hemorrhage and accompanied with narrow time window and strict contraindications, which limited its clinical application (Whiteley, Slot, Fernandes, Sandercock, & Wardlaw, 2012). Currently, for a large population of patients with AIS, seeking safe and effective treatment for AIS remains the focus of global medical attention.
Human urinary kallindinogenase (HUK) is a tissue kallikrein extracted from male urine (Miao, Deng, Zhang, Xie, & Feng, 2016). It is a new drug on the market in recent years and has been approved by China Food and Drug Administration (CFDA) for the treatment of stroke. Considerable researches have confirmed that HUK could increase the blood flow and oxygen supply, improve cerebral blood circulation, and promote angiogenesis and cerebral perfusion in ischemic regions, and thus improving neurological function (Han et al., 2015;Li, Chen, et al., 2015). Besides, the safety and effectiveness of HUK for stroke patients have been verified by phase II/III clinical trials (Deyun, 2005). Nevertheless, the effective rate of HUK was approximate 80% (Li, Zha, et al., 2015), indicating the HUK was still ineffective for some patients. Previously, Li, Chen, et al. (2015) have proposed that the clinical efficacy of HUK on patients with different TOAST (The Trial of Org 10172 in Acute Stroke Treatment) type AIS was different. Thus, we hypothesized that the personalized therapy options with HUK are likely to be more appropriate for AIS patients.
Previously, Gao, Wang, Xu, Li, and Wang (2011) have provided an innovative classification system for stroke, Chinese ischemic stroke subclassification (CISS), which offered more detailed information on the pathophysiology of stroke. Therefore, based on this classification system, we hoped to find a subtype that was more suitable for HUK therapy by evaluating the effects of different subtypes on clinical efficacy. Therefore, we evaluated the effectiveness of HUK and analyzed risk factors of clinical efficacy. Furthermore, according to CISS, the effects of different subtypes on the clinical efficacy of HUK were evaluated, aiming to explore the optimal therapy strategies of HUK in the treatment of AIS.

| Treatment and grouping
According to the treatment program, the patients with AIS were divided into two groups: HUK group (n = 132) and control group

| Outcome and clinical assessment
National Institute of Health Stroke Scale score was performed to evaluate the neurological function and clinical efficacy. NIHSS scores before and after treatment among patients in two groups were recorded. According to the improvement degree of clinical NIHSS scores, clinical efficacy was divided into six categories including: (a) basic recovery (NIHSS score decreased by more than 90%); (b) significant improvement (NIHSS score decreased by 46%-89%); improvement (NIHSS score decreased by 18%-45%); (c) no-change (NIHSS score decreased 0%-18%, or increased <18%); (d) deterioration (NIHSS score increased more than 18%); and (e) death. The basic recovery, significant improvement, and improvement were regarded as effectivity. The no-change, deterioration, and death were regarded as inefficiency (Qingtang, 1996;Li, Zha, et al., 2015).
For analysis, the level of homocysteine was defined as a categorical variables. Due to Chinese adults who do not eat food fortified with folic acid, the optimal threshold of homocysteine level (20 μmol/L) was determined according to the previous report (Refsum et al., 2004).

| Statistical analysis
Statistical analysis was performed with SPSS statistics 17.0 (IBM).
Mean ± standard deviation (SD) was used to represent the continuous variables. Qualitative data were described by number or percentage.
The normality of the data distribution was tested with Kolmogorov-Smirnov test. Comparison in two groups was performed with Student's t test or Pearson's Chi-square test. Logistic regression was used to identify the independent risk factors. Differences were considered statistically significant when p < .05.

| Initial patient characteristics
The baseline characteristics of patients in two groups were shown in

| NIHSS scores and efficacy evaluation before and after treatment
At baseline, no significant difference was found in NIHSS scores between two groups (p = .30). After receiving the specified treatment for 14 days, NIHSS scores in two groups were all significantly reduced compared with that before treatment (p < .001, Figure 1a).
Besides, the NIHSS score of HUK group was significant lower than that of control group, indicating that HUK has significant effect on improving the neurological function of ASI patients (p = .009). In addition, the distribution of the NIHSS scores changed before and after treatment (Figure 1b) Pearson's Chi-square result showed that the total effectiveness rate of HUK group was significant higher than that of control group (p = .003).

| NIHSS scores and efficacy evaluation of different subtypes
With regard to the five subtypes of CISS classification, no significant difference was found between the subtypes of the two groups at baseline (p > .05, Figure 2). After treatment, a significant reduction HUK group was found to be significant lower than that in control group (p = .005, Figure 2).
The clinical efficacy for patients with different subtypes was showed in Table 2. The effectiveness rate of LAA subtype showed a statistically significant difference between two groups (p = .004, Table 2), while the other subtypes showed no significant difference between two groups (p > .05, Table 2).  We confirmed that HUK significantly improved the neurological function of AIS patients with total effectiveness rate of 71.2%.

| D ISCUSS I ON
These results are consistent with previous research reports (Song et al., 2018;Wei et al., 2018). A systemic review has also demonstrated that 2,117 patients (22 trials) benefited from HUK treatment and the efficacy rate was 87% in China (Zhang, Tao, Liu, & Wang, 2012).
Several hypotheses have been proposed to explain the mechanism of HUK on AIS (Chen et al., 2010;Han et al., 2015;Li, Chen, et al., 2015). HUK is a tissue kallikrein, could cleave low molecular weight kininogen to vasodilator kinin peptide (Emanuelia & Madeddu, 2003). Then, it triggers a series of biological effects by activating bradykinin B1 and B2 receptors through the KKS system (Campbell, 2001;Emanuelia & Madeddu, 2003). Another explanation was that HUK could enhance angiogenesis in the subventricular zone and increases capillary density in cerebral peri-infarct area, which in turn improves collateral circulation (Han et al., 2015). Besides, Song et al. have reported that HUK improved symptoms of neurological deficiency by enhancing remodeling of long-term cortical motor function in patients with AIS (Song, Han, & Liu, 2012). Although multiple works have focused on the mechanism of HUK, conclusion was not definitively made. Further studies on a large scale are still needed to verify the effect of HUK in clinical practice.
The highlight of this study was the finding of better clinical efficacy of HUK therapy in LAA subtype patients, indicating that the HUK therapy is more appropriate for patients with LAA subtype than the other subtypes. A previous study has reported the clinical efficacy of HUK in the treatment of AIS according to TOAST classification (Li, Zha, et al., 2015). They came to a similar conclusion with us. In our study, CISS was used for the classification, which was an improved and more rational way of stroke subtyping that takes into consideration of etiological and pathophysiological information . On the basis of CISS, LAA is the most common cause of ischemic stroke (Gao et al., 2011). Patients with LAA subtype were prone to form atherosclerotic thrombosis and thus may result in arterial TA B L E 2 Comparisons of clinical efficacy between two groups according to the CISS subtypes after treatment We also analyzed the risk factors of HUK clinical efficacy and found that the use of HUK and the lower level of homocysteine were protective factors for the clinical efficacy of HUK. There is no doubt that patients with AIS would be benefited from HUK therapy, which has been confirmed by considerable clinical trials (Ni et al., 2017;Zhang et al., 2012

ACK N OWLED G M ENT
None.

CO N FLI C T O F I NTE R E S T
The authors declare that they have no conflict of interest.

DATA AVA I L A B I L I T Y S TAT E M E N T
The data that support the findings of this study are available from the corresponding author upon reasonable request.