Role of Thrombin in Central Nervous System Injury and Disease

Zhou

et al. 2022

J Neuroinflammation

Background Nafamostat mesylate (nafamostat, NM) is an FDA-approved serine protease inhibitor that exerts anti-neuroinflammation and neuroprotective effects following rat spinal cord injury (SCI). However, clinical translation of nafamostat has been limited by an unclear administration time window and mechanism of action. Methods Time to first dose of nafamostat administration was tested on rats after contusive SCI. The optimal time window of nafamostat was screened by evaluating hindlimb locomotion and electrophysiology. As nafamostat is a serine protease inhibitor known to target thrombin, we used argatroban (Arg), a thrombin-specific inhibitor, as a positive control in the time window experiments. Western blot and immunofluorescence of thrombin expression level and its enzymatic activity were assayed at different time points, as well its receptor, the protease activated receptor 1 (PAR1) and downstream protein matrix metalloproteinase-9 (MMP9). Blood–spinal cord barrier (BSCB) permeability leakage indicator Evans Blue and fibrinogen were analyzed along these time points. The infiltration of peripheral inflammatory cell was observed by immunofluorescence. Results The optimal administration time window of nafamostat was 2–12 h post-injury. Argatroban, the thrombin-specific inhibitor, had a similar pattern. Thrombin expression peaked at 12 h and returned to normal level at 7 days post-SCI. PAR1, the thrombin receptor, and MMP9 were significantly upregulated after SCI. The most significant increase of thrombin expression was detected in vascular endothelial cells (ECs). Nafamostat and argatroban significantly downregulated thrombin and MMP9 expression as well as thrombin activity in the spinal cord. Nafamostat inhibited thrombin enrichment in endothelial cells. Nafamostat administration at 2–12 h after SCI inhibited the leakage of Evans Blue in the epicenter and upregulated tight junction proteins (TJPs) expression. Nafamostat administration 8 h post-SCI effectively inhibited the infiltration of peripheral macrophages and neutrophils to the injury site. Conclusions Our study provides preclinical information of nafamostat about the administration time window of 2–12 h post-injury in contusive SCI. We revealed that nafamostat functions through inhibiting the thrombin-mediated BSCB breakdown and subsequent peripheral immune cells infiltration.

Section: Discussionmentioning

confidence: 99%

Delayed administration of nafamostat mesylate inhibits thrombin-mediated blood–spinal cord barrier breakdown during acute spinal cord injury in rats

Zhou

et al. 2022

J Neuroinflammation

J Cereb Blood Flow Metab

“…It is suggested that in other CNS disorders active thrombin might play a role. 56 These disorders include, but are not limited to, focal cerebral ischemia (ischemic stroke), intracerebral hemorrhage (ICH), 57 arteriovenous malformations (AVMs), 58 multiple sclerosis (MS), 59 germinal matrix hemorrhage, 60 intracerebral hemorrhage due to hypertension, 61,62 traumatic brain injury, 63 and CNS neoplasms. 64 To our knowledge at this time the ability of thrombin to degrade cerebral vascular components has not been studied in those disorders or their model systems.…”

Section: Discussionmentioning

confidence: 99%

Intracerebral hemorrhage and thrombin-induced alterations in cerebral microvessel matrix

Hawkins

Izawa

et al. 2022

Four phase III clinical trials of oral direct factor Xa or thrombin inhibitors demonstrated significantly lower intracranial hemorrhage compared to warfarin in patients with nonvalvular-atrial fibrillation. This is counter-intuitive to the principle that inhibiting thrombosis should increase hemorrhagic risk. We tested the novel hypothesis that anti-thrombin activity decreases the risk of intracerebral hemorrhage by directly inhibiting thrombin-mediated degradation of cerebral microvessel basal lamina matrix, responsible for preventing hemorrhage. Collagen IV, laminin, and perlecan each contain one or more copies of the unique α-thrombin cleavage site consensus sequence. In blinded controlled experiments, α-thrombin significantly degraded each matrix protein in vitro and in vivo in a concentration-dependent fashion. In vivo stereotaxic injection of α-thrombin significantly increased permeability, local IgG extravasation, and hemoglobin (Hgb) deposition together with microvessel matrix degradation in a mouse model. In all formats the direct anti-thrombin dabigatran completely inhibited matrix degradation by α-thrombin. Fourteen-day oral exposure to dabigatran etexilate-containing chow completely inhibited matrix degradation, the permeability to large molecules, and cerebral hemorrhage associated with α-thrombin. These experiments demonstrate that thrombin can degrade microvessel matrix, leading to hemorrhage, and that inhibition of microvessel matrix degradation by α-thrombin decreases cerebral hemorrhage. Implications for focal ischemia and other conditions are discussed.

“…Increasing evidence supports key roles of complement and coagulation in the neuroinflammatory damage induced following stroke, neoplasms, epilepsy, traumatic brain and nerve injury, and neurodegenerative diseases [ 73 , 141 , 142 ]. Coagulation and inflammation are well-known to interact with each other in both physiological and pathophysiological states of the nervous system [ 14 , 46 , 113 , 143 ].…”

Section: Discussionmentioning

confidence: 99%

Complement and Coagulation System Crosstalk in Synaptic and Neural Conduction in the Central and Peripheral Nervous Systems

et al. 2021

Complement and coagulation are both key systems that defend the body from harm. They share multiple features and are similarly activated. They each play individual roles in the systemic circulation in physiology and pathophysiology, with significant crosstalk between them. Components from both systems are mapped to important structures in the central nervous system (CNS) and peripheral nervous system (PNS). Complement and coagulation participate in critical functions in neuronal development and synaptic plasticity. During pathophysiological states, complement and coagulation factors are upregulated and can modulate synaptic transmission and neuronal conduction. This review summarizes the current evidence regarding the roles of the complement system and the coagulation cascade in the CNS and PNS. Possible crosstalk between the two systems regarding neuroinflammatory-related effects on synaptic transmission and neuronal conduction is explored. Novel treatment based on the modulation of crosstalk between complement and coagulation may perhaps help to alleviate neuroinflammatory effects in diseased states of the CNS and PNS.