LF16-0687 a novel non-peptide bradykinin B2 receptor antagonist reduces vasogenic brain edema from a focal lesion in rats

Hyperglycemia Predicts Blend Sign in Patients with Intracerebral Hemorrhage

Background

Predictive values of admission blood glucose for early hematoma expansion in patients with intracranial hemorrhage (ICH) remain controversial. Blend sign is a novel image predictor for early hematoma growth that suggests presence of active bleeding. We investigated the association between hyperglycemia and blend sign in predicting early hematoma growth in ICH patients.

Material/Methods

All patients with intracranial hemorrhage were retrospectively reviewed. Clinical characteristics and radiological parameters were collected. Blood glucose was measured within 24 h after onset. CT scan results for hematoma expansion and blend sign were evaluated by 2 readers. Multivariate logistic regression analyses were applied to reveal the associations between hematoma growth and blend sign, as well as other variables.

Results

Out of 164 patients with ICH, 52 exhibited early hematoma growth and 18 of these were diagnosed with blend sign. Average blood glucose was 7.53 mmol/L among all patients. By using multivariate analyses, the time of CT scan baseline, GCS score, hematoma size, blend sign, and blood glucose were associated with hematoma expansion, whereas only hyperglycemia was associated with blend sign.

Conclusions

Admission hyperglycemia is associated with hematoma expansion in the presence of blend sign. These findings suggest that elevated blood glucose is a possible factor predicting continuous bleeding. Strategies to control blood glucose and ameliorate hematoma growth are urgently needed and will be investigated in our future studies.

Implication of the Kallikrein-Kinin system in neurological disorders: Quest for potential biomarkers and mechanisms

Neurological disorders represent major health concerns in terms of comorbidity and mortality worldwide. Despite a tremendous increase in our understanding of the pathophysiological processes involved in disease progression and prevention, the accumulated knowledge so far resulted in relatively moderate translational benefits in terms of therapeutic interventions and enhanced clinical outcomes. Aiming at specific neural molecular pathways, different strategies have been geared to target the development and progression of such disorders. The kallikrein-kinin system (KKS) is among the most delineated candidate systems due to its ubiquitous roles mediating several of the pathophysiological features of these neurological disorders as well as being implicated in regulating various brain functions. Several experimental KKS models revealed that the inhibition or stimulation of the two receptors of the KKS system (B1R and B2R) can exhibit neuroprotective and/or adverse pathological outcomes. This updated review provides background details of the KKS components and their functions in different neurological disorders including temporal lobe epilepsy, traumatic brain injury, stroke, spinal cord injury, Alzheimer's disease, multiple sclerosis and glioma. Finally, this work will highlight the putative roles of the KKS components as potential neurotherapeutic targets and provide future perspectives on the possibility of translating these findings into potential clinical biomarkers in neurological disease.

Secondary Hematoma Expansion and Perihemorrhagic Edema after Intracerebral Hemorrhage: From Bench Work to Practical Aspects

Intracerebral hemorrhages (ICH) represent about 10-15% of all strokes per year in the United States alone. Key variables influencing the long-term outcome after ICH are hematoma size and growth. Although death may occur at the time of the hemorrhage, delayed neurologic deterioration frequently occurs with hematoma growth and neuronal injury of the surrounding tissue. Perihematoma edema has also been implicated as a contributing factor for delayed neurologic deterioration after ICH. Cerebral edema results from both blood-brain barrier disruption and local generation of osmotically active substances. Inflammatory cellular mediators, activation of the complement, by-products of coagulation and hemolysis such as thrombin and fibrin, and hemoglobin enter the brain and induce a local and systemic inflammatory reaction. These complex cascades lead to apoptosis or neuronal injury. By identifying the major modulators of cerebral edema after ICH, a therapeutic target to counter degenerative events may be forthcoming.

Role of the kallikrein-kinin system in traumatic brain injury

Traumatic brain injury (TBI) is a major cause of mortality and morbidity worldwide. Despite improvements in acute intensive care, there are currently no specific therapies to ameliorate the effects of TBI. Successful therapeutic strategies for TBI should target multiple pathophysiologic mechanisms that occur at different stages of brain injury. The kallikrein-kinin system is a promising therapeutic target for TBI as it mediates key pathologic events of traumatic brain damage, such as edema formation, inflammation, and thrombosis. Selective and specific kinin receptor antagonists and inhibitors of plasma kallikrein and coagulation factor XII have been developed, and have already shown therapeutic efficacy in animal models of stroke and TBI. However, conflicting preclinical evaluation, as well as limited and inconclusive data from clinical trials in TBI, suggests that caution should be taken before transferring observations made in animals to humans. This review summarizes current evidence on the pathologic significance of the kallikrein-kinin system during TBI in animal models and, where available, the experimental findings are compared with human data.

Kinin receptor antagonists as potential neuroprotective agents in central nervous system injury

Injury to the central nervous system initiates complex physiological, cellular and molecular processes that can result in neuronal cell death. Of interest to this review is the activation of the kinin family of neuropeptides, in particular bradykinin and substance P. These neuropeptides are known to have a potent pro-inflammatory role and can initiate neurogenic inflammation resulting in vasodilation, plasma extravasation and the subsequent development of edema. As inflammation and edema play an integral role in the progressive secondary injury that causes neurological deficits, this review critically examines kinin receptor antagonists as a potential neuroprotective intervention for acute brain injury, and more specifically, traumatic brain and spinal cord injury and stroke.

LF 16-0687 Ms, a bradykinin B2 receptor antagonist, reduces ischemic brain injury in a murine model of transient focal cerebral ischemia

1. Bradykinin promotes neuronal damage and brain edema through the activation of the B(2) receptor. The neuroprotective effect of LF 16-0687 Ms, a B(2) receptor antagonist, has been described when given prior to induction of transient focal cerebral ischemia in rat, but there are no data regarding the consequence of a treatment when given after injury. Therefore, in a murine model of transient middle cerebral artery occlusion (MCAO), we evaluated the effect of LF 16-0687 Ms given prior to and/or after the onset of ischemia on neurological deficit, infarct volume and inflammatory responses including cerebral edema, blood-brain barrier (BBB) disruption and neutrophil accumulation. 2. LF 16-0687 Ms (1, 2 and 4 mg kg(-1)) administered 0.5 h before and, 1.25 and 6 h after MCAO, decreased the infarct volume by a maximum of 33% and significantly improved the neurological recovery. 3. When given at 0.25 and 6.25 h after MCAO, LF 16-0687 Ms (1.5, 3 and 6 mg kg(-1)) decreased the infarct volume by a maximum of 25% and improved the neurological score. 4. Post-treatment with LF 16-0687 Ms (1.5 mg kg(-1)) significantly decreased brain edema (-28%), BBB disruption (-60%) and neutrophil accumulation (-65%) induced by ischemia. Physiological parameters were not modified by LF 16-0687 Ms. 5. These data emphasize the role of bradykinin B(2) receptor in the development of infarct lesion, neurological deficit and inflammatory responses resulting from transient focal cerebral ischemia. Therefore, B(2) receptor antagonist might represent a new therapeutic approach in the pharmacological treatment of stroke.

Astrocyte-endothelial interactions and blood-brain barrier permeability

The blood-brain barrier (BBB) is formed by brain endothelial cells lining the cerebral microvasculature, and is an important mechanism for protecting the brain from fluctuations in plasma composition, and from circulating agents such as neurotransmitters and xenobiotics capable of disturbing neural function. The barrier also plays an important role in the homeostatic regulation of the brain microenvironment necessary for the stable and co-ordinated activity of neurones. The BBB phenotype develops under the influence of associated brain cells, especially astrocytic glia, and consists of more complex tight junctions than in other capillary endothelia, and a number of specific transport and enzyme systems which regulate molecular traffic across the endothelial cells. Transporters characteristic of the BBB phenotype include both uptake mechanisms (e.g. GLUT-1 glucose carrier, L1 amino acid transporter) and efflux transporters (e.g. P-glycoprotein). In addition to a role in long-term barrier induction and maintenance, astrocytes and other cells can release chemical factors that modulate endothelial permeability over a time-scale of seconds to minutes. Cell culture models, both primary and cell lines, have been used to investigate aspects of barrier induction and modulation. Conditioned medium taken from growing glial cells can reproduce some of the inductive effects, evidence for involvement of diffusible factors. However, for some features of endothelial differentiation and induction, the extracellular matrix plays an important role. Several candidate molecules have been identified, capable of mimicking aspects of glial-mediated barrier induction of brain endothelium; these include TGFbeta, GDNF, bFGF, IL-6 and steroids. In addition, factors secreted by brain endothelial cells including leukaemia inhibitory factor (LIF) have been shown to induce astrocytic differentiation. Thus endothelium and astrocytes are involved in two-way induction. Short-term modulation of brain endothelial permeability has been shown for a number of small chemical mediators produced by astrocytes and other nearby cell types. It is clear that endothelial cells are involved in both long- and short-term chemical communication with neighbouring cells, with the perivascular end feet of astrocytes being of particular importance. The role of barrier induction and modulation in normal physiology and in pathology is discussed.