Clinical Significance of DKK2 Protein in Cerebral Ischemia-reperfusion Injury

Ischemic stroke refers to ischaemic and hypoxic necrosis of brain tissue caused by narrowing or occlusion of the blood vessels in the brain and accounts for approximately 80% of all strokes. It is characterized by high morbidity, mortality, disability, and recurrence rates. Reperfusion is currently the most effective treatment for the acute phase of ischaemic stroke, including pharmacological thrombolysis and mechanical embolization. Although successful revascularization can reperfuse areas of cerebral ischemia, it can cause acute cerebrovascular damage while restoring blood supply to brain tissue, leading to disruption of the blood-brain barrier (BBB), increased risk of cerebral edema and hemorrhagic transformation, and increased inflammation of neural tissue, which can further damage brain tissue. Targeted reduction of endothelial damage from ischemia-reperfusion will therefore effectively protect neurons from subsequent damage, thereby minimizing neurological impairment after stroke and maximizing the benefit of revascularisation therapy.

The Wnt signaling pathway has been identified by several research groups worldwide as a key regulatory pathway in the maintenance of cerebrovascular and neural cell function. The DKK (Dickkopf-related protein) family of proteins is the most representative group of classical Wnt signaling pathway inhibitors. DKK proteins competitively bind to the Wnt co-receptor LRP5/6, thereby inhibiting the activity of Wnt proteins and exerting their inhibitory effects on the Wnt/β-catenin signaling pathway. We initially found that DKK2 serum levels increased significantly after 4.5 h of recanalization therapy in 20 patients with large vessel occlusive acute stroke, and decreased after 24 h. Increased DKK2 levels were strongly associated with an unfavorable prognosis. This was corroborated in animal models as well, DKK2 expression levels in ischaemic brain tissue and peripheral blood were both significantly elevated and rapidly upregulated within 6-12 h of the onset of cerebral ischemia-reperfusion in mice. In vitro cellular assays showed that DKK2 protein significantly inhibited the activity of the Wnt/β-catenin signaling pathway. We further study showed that upregulation of DKK2 protein levels in the blood of mice by intravenous administration of adenovirus expressing DKK2 protein significantly increased cerebral infarction and neurological impairment in mice with stroke. The increased expression of DKK2 protein in brain tissue is the main reason for the downregulation of Wnt/β-catenin signaling pathway activity after ischemia/reperfusion, which leads to blood-brain barrier damage, neuronal cell death, and neuroinflammation, and ultimately promotes brain tissue damage and neurological dysfunction. It is a new target for drug therapy and has great scientific significance and clinical application prospects.

This clinical study is conducted at Dongguan Hospital of Southern Medical University and Nanfang Hospital of Southern Medical University. Acute ischemic stroke patients with large vessel occlusion who received mechanical thrombectomy therapy and are successfully revascularized will be included and followed up for 90 d, along with testing serum levels of DKK2 protein to explore its correlation with the prognosis of enrolled patients. Venous blood samples will be collected before, and 24 h, 48 h, and 72 h after revascularization treatment in enrolled patients. Venous blood samples will be collected before and 0h, 24 h, 48 h, and 72 h after revascularisation treatment to test serum KKD2 level, and cranial CT examination will be performed before, 24 h, and 72 h after revascularization treatment to detect the occurrence of the transformation of hemorrhage, the severity of cerebral edema, and midline shift after revascularisation treatment. Blood-brain barrier injury-related indicators (MMP-9, ICAM-1) and inflammation-related indicators (IL-6, IL-1β, TNF-α, IL-10) will be measured at each time point of DKK2 testing. NIHSS scores will be evaluated before, 0h (immediately after revascularization treatment), 24 h, 48 h, 72 h, and 7 d after revascularization treatment. The mRS scores will be followed up at 30 days and 90 days after the onset to clarify the relationship between serum DKK2 levels and large vessel occlusion. We aim to investigate the mechanism of DKK2 causing adverse clinical outcomes such as BBB leakage, cerebral edema, and hemorrhagic transformation at a real-world clinical level by collecting blood samples, clinical follow-up, and neurological scoring from stroke patients by measuring DKK2 levels and brain imaging parameters for quantitative assessment.