Kallikrein gene transfer induces angiogenesis and further improves regional cerebral blood flow in the early period after cerebral ischemia/reperfusion in rats

The temporal dynamic of bradykinin type 2 receptor effects reveals its neuroprotective role in the chronic phase of cerebral and retinal ischemic injury

The activation of the bradykinin type 2 receptor is intricately involved in acute post-ischemic inflammatory responses. However, its precise role in different stages of ischemic injury, especially in the chronic phase, remains unclear. Following simultaneous cerebral and retinal ischemia, bradykinin type 2 receptor knockout mice and their controls were longitudinally monitored for 35 days via magnetic resonance imaging, fundus photography, fluorescein angiography, behavioral assessments, vascular permeability measurements, and immunohistochemistry, as well as glycemic status assessments. Without impacting the lesion size, bradykinin type 2 receptor deficiency reduced acute cerebral vascular permeability preventing the loss of pericytes and tight junctions. In the chronic phase of ischemia, however, it resulted in increased astrogliosis and cortical neuronal loss, as well as higher functional deficits. The retinal findings demonstrated a similar pattern. Bradykinin type 2 receptor deficiency delayed, but exacerbated the development of retinal necrosis, increased subacute vascular permeability, and promoted retinal ganglion cell loss in the chronic phase of ischemia. This investigation sheds light on the temporal dynamic of bradykinin type 2 receptor effects in ischemia, pointing to a therapeutic potential in the subacute and chronic phases of ischemic injury.

Protective effects of human urinary kallidinogenase against corticospinal tract damage in acute ischemic stroke patients

This study aimed to assess the effects of human urinary kallidinogenase (HUK) on motor function outcome and corticospinal tract recovery in patients with acute ischemic stroke (AIS). This study was a randomized, controlled, single-blinded trial. Eighty AIS patients were split into two groups: the HUK and control groups. The HUK group was administered HUK and standard treatment, while the control group received standard treatment only. At admission and discharge, the National Institutes of Health Stroke Scale (NIHSS), Barthel Index (BI) and muscle strength were scored. The primary endpoint was the short-term outcomes of AIS patients under different treatments. The secondary endpoint was the degree of corticospinal tract fiber damage under different treatments. There was a significant improvement in the NIHSS Scale, BI and muscle strength scores in the HUK group compared with controls (Mann-Whitney U test; P  < 0.05). Diffusion tensor tractography classification and intracranial arterial stenosis were independent predictors of short-term recovery by linear regression analysis. The changes in fractional anisotropy (FA) and apparent diffusion coefficient (ADC) decline rate were significantly smaller in the HUK group than in the control group ( P <  0.05). Vascular endothelial growth factor (VEGF) increased significantly after HUK treatment ( P  < 0.05), and the VEGF change was negatively correlated with changes in ADC. HUK is beneficial for the outcome in AIS patients especially in motor function recovery. It may have protective effects on the corticospinal tract which is reflected by the reduction in the FA and ADC decline rates and increased VEGF expression. The study was registered on ClinicalTrials.gov (unique identifier: NCT04102956).

Angiogenesis after ischemic stroke

Owing to its high disability and mortality rates, stroke has been the second leading cause of death worldwide. Since the pathological mechanisms of stroke are not fully understood, there are few clinical treatment strategies available with an exception of tissue plasminogen activator (tPA), the only FDA-approved drug for the treatment of ischemic stroke. Angiogenesis is an important protective mechanism that promotes neural regeneration and functional recovery during the pathophysiological process of stroke. Thus, inducing angiogenesis in the peri-infarct area could effectively improve hemodynamics, and promote vascular remodeling and recovery of neurovascular function after ischemic stroke. In this review, we summarize the cellular and molecular mechanisms affecting angiogenesis after cerebral ischemia registered in PubMed, and provide pro-angiogenic strategies for exploring the treatment of ischemic stroke, including endothelial progenitor cells, mesenchymal stem cells, growth factors, cytokines, non-coding RNAs, etc.

A Network Pharmacology Approach to Predict the Proangiogenesis Mechanism of Huangqi-Honghua Herb Pair after Cerebral Ischemia

Objective

Huangqi-Honghua herb pair is known for its medicinal value to treat Qi deficiency and blood stasis syndrome with a long history in clinical practice. To understand its possible mechanism in a systematic study, a network pharmacological method was addressed.

Methods

Detailed information on the HH compounds was obtained from two public databases, and oral bioavailability (OB) and drug-like (DL) of the compounds were evaluated. A correlation between HH compounds, its potential targets, and known targets was extrapolated, and the herb-compound-target-disease (H-C-T-D) network was established. Next, the pathway enrichment and essential genes were analyzed. Then, three key genes (VEGFA, VEGFR2, and eNOS), highly associated with angiogenesis, were screened and verified through western blot assay.

Results

Out of 276 compounds, 21 HH compounds and 78 target genes regulating the major pathways associated with CI in the network are analyzed. The bioactive compounds in HH were active in various signal transduction pathways such as the toll-like receptor signaling pathway, VEGF signaling pathway, TNF signaling pathway, and HIF-1 signaling pathway are important pathways that may regulate anti-inflammatory, antiapoptotic, immune correlation, and antioxidative effects. The core genes are PTGS2, TNF, NOS2, IL6, BCL2, IL1B, SOD2, NOS3, SOD1, MMP9, and VEGFA. The in vitro results suggested that HH treatment could significantly elevate the expression of proangiogenic genes such as VEGFA, VEGFR2, and eNOS compared with OGD groups.

Conclusions

Our results predict that HH may regulate the expression of VEGFA, VEGFR2, and eNOS via the VEGF and HIF-1 signaling pathway to promote angiogenesis and alleviate cerebral ischemia injury.

High Level of Serum Tissue Kallikrein Is Associated with Favorable Outcome in Acute Ischemic Stroke Patients

Background/Objectives

We sought to assess the association between a serum tissue kallikrein (TK) level and a 90-day outcome in acute ischemic stroke (AIS) patients who received acute reperfusion therapy.

Methods

Consecutive AIS patients within 6 hours after stroke onset between December 2015 and August 2017 were prospectively recruited. Blood samples were collected before acute reperfusion therapy for serum TK measurement. Outcome was modified Rankin scale (mRS) score at 90 days after stroke onset. Binary logistic regression was performed to analyze the association between the baseline TK level and the clinical outcome.

Results

Between December 2015 and August 2017, 75 patients (age range from 33 to 91 years, 72.0% male) were recruited in this study. Higher baseline TK was independently associated with a favorable functional outcome (mRS 0-2) (odds ratio 1.01, 95% confidence interval (CI) 1.00-1.02, p = 0.047) and low mortality rate (odds ratio 0.98, 95% CI 0.96-1.00, p = 0.049) at 90 days. Increased TK level was associated with 90 d mRS (0-2) with area under the curve of 0.719 (95% CI 0.596-0.842; p = 0.002).

Conclusions

Serum TK can be a promising predictor of clinical outcome in AIS patients who received acute reperfusion therapy.

Human tissue kallikrein in the treatment of acute ischemic stroke

Acute ischemic stroke (AIS) remains a major cause of death and disability throughout the world. The most severe form of stroke results from large vessel occlusion of the major branches of the Circle of Willis. The treatment strategies currently available in western countries for large vessel occlusion involve rapid restoration of blood flow through removal of the offending blood clot using mechanical or pharmacological means (e.g. tissue plasma activator; tPA). This review assesses prospects for a novel pharmacological approach to enhance the availability of the natural enzyme tissue kallikrein (KLK1), an important regulator of local blood flow. KLK1 is responsible for the generation of kinins (bradykinin and kallidin), which promote local vasodilation and long-term vascularization. Moreover, KLK1 has been used clinically as a direct treatment for multiple diseases associated with impaired local blood flow including AIS. A form of human KLK1 isolated from human urine is approved in the People's Republic of China for subacute treatment of AIS. Here we review the rationale for using KLK1 as an additional pharmacological treatment for AIS by providing the biochemical mechanism as well as the human clinical data that support this approach.

Tissue kallikrein protects against ischemic stroke by suppressing TLR4/NF-κB and activating Nrf2 signaling pathway in rats

Brain damage following cerebral ischemia-reperfusion (I/R) is a complicated pathophysiological course, in which inflammation and oxidative stress have been suggested to serve an important role. Toll-like receptor 4 (TLR4) has been suggested to be involved in secondary inflammatory process in cerebral ischemia. Nuclear factor erythroid 2-related factor 2 (Nrf2), an important regulator of the antioxidant host defense, maintains the cellular redox homeostasis. Tissue kallikrein (TK) has been proven to elicit a variety of biological effects in ischemic stroke through its anti-inflammatory and anti-oxidant properties. However, the mechanisms underlying its beneficial effects remain poorly defined. The present study examined the hypothesis that TK attenuates ischemic cerebral injury via the TLR4/nuclear factor-κB (NF-κB) and Nrf2 signaling pathways. Using a transient rat middle cerebral artery occlusion (MCAO) model, the effects of immediate and delayed TK treatment subsequent to reperfusion were investigated. The neurological deficits, infarct size, and the expression of TLR4/NF-κB and Nrf2 pathway in ischemic brain tissues were measured at 24 following MCAO. The results indicated that TK immediate treatment significantly improved neurological deficits and reduced the infarct size, accompanied by the inhibition of TLR4 and NF-κB levels, and the activation of Nrf2 pathway. Furthermore, TK delayed treatment also exerted neuroprotection against I/R injury. However, the neuroprotective effect of TK immediate treatment was better compared with that of TK delayed treatment. In conclusion, the results indicated that TK protected the brain against ischemic injury in rats after MCAO through its anti-oxidative and anti-inflammatory effects. Suppression of TLR4/NF-κB and activation of the Nrf2 pathway contributed to the neuroprotective effects induced by TK in cerebral ischemia. Therefore, TK may provide an effective intervention with a wider therapeutic window for ischemic stroke.

Tissue Kallikrein Activity, Detected by a Novel Method, May Be a Predictor of Recurrent Stroke: A Case-Control Study

Aim. Tissue kallikrein (TK) protein content in plasma has been shown to be negatively associated with both incident and recurrent strokes. The aims of this study were to develop a novel method for detecting TK activity and to investigate its association with event-free survival over 5 years in Chinese first-ever stroke patients. Methods. We designed a case-control study with 321 stroke patients (174: ischemic stroke, 147: hemorrhagic stroke) and 323 healthy local controls. TK activity was measured by a novel assay utilizing the immunological characteristics of TK and the catalysis of benzoyl arginine ethyl ester hydrochloride (BAEE). Results. TK protein levels above 0.200 mg/L in plasma were not associated with urinary TK activity or the risk of stroke recurrence. TK activity was significantly lower in stroke patients compared with controls (1.583 ± 0.673 Eu/mL versus 1.934 ± 0.284 Eu/mL, P < 0.001). After adjusting for traditional risk factors, TK activity was negatively associated, in a dose-response manner, with the risk of overall stroke recurrence and positively associated with event-free survival during a 5-year follow-up (relative risk (RR), 0.69; 95% CI, 0.57–0.84; P < 0.001). Conclusions. Our findings suggest that urinary TK activity may be a stronger predictor of stroke recurrence than plasma TK levels.

Human Urinary Kallidinogenase Promotes Angiogenesis and Cerebral Perfusion in Experimental Stroke

Angiogenesisis a key restorative mechanism in response to ischemia, and pro-angiogenic therapy could be beneficial in stroke. Accumulating experimental and clinical evidence suggest that human urinary kallidinogenase (HUK) improves stroke outcome, but the underlying mechanisms are not clear. The aim of current study was to verify roles of HUK in post-ischemic angiogenesis and identify relevant mediators. In rat middle cerebral artery occlusion (MCAO) model, we confirmed that HUK treatment could improve stroke outcome, indicated by reduced infarct size and improved neurological function. Notably, the ¹⁸F-FDG micro-PET scan indicated that HUK enhanced cerebral perfusion in rats after MCAO treatment. In addition, HUK promotespost-ischemic angiogenesis, with increased vessel density as well as up-regulated VEGF andapelin/APJ expression in HUK-treated MCAO mice. In endothelial cell cultures, induction of VEGF and apelin/APJ expression, and ERK1/2 phosphorylation by HUK was further confirmed. These changes were abrogated by U0126, a selective ERK1/2 inhibitor. Moreover, F13A, a competitive antagonist of APJ receptor, significantly suppressed HUK-induced VEGF expression. Furthermore, angiogenic functions of HUK were inhibited in the presence of selective bradykinin B1 or B2 receptor antagonist both in vitro and in vivo. Our findings indicate that HUK treatment promotes post-ischemic angiogenesis and cerebral perfusion via activation of bradykinin B1 and B2 receptors, which is potentially due to enhancement expression of VEGF and apelin/APJ in ERK1/2 dependent way.