The Use of Serum Matrix Metalloproteinases in Cerebral Amyloid Angiopathy-Related Intracerebral Hemorrhage and Cognitive Impairment

Usefulness of Serum Translocator Protein as a Potential Predictive Biochemical Marker of Three-Month Cognitive Impairment After Acute Intracerebral Hemorrhage: A Prospective Observational Cohort Study

Background

Translocator protein (TSPO) is a biomarker of neuroinflammation and brain injury. This study aimed to ascertain the potential of serum TSPO as a predictor of cognitive impairment after acute intracerebral hemorrhage (ICH).

Methods

In this prospective observational cohort study, 276 patients with supratentorial ICH were randomly assigned to two groups (184 patients in the study group and 92 in the validation group) in a 2:1 ratio. Serum TSPO levels were gauged at admission, and cognitive status was assessed using the Montreal Cognitive Assessment Scale (MoCA) post-stroke 3 months. A MoCA score of < 26 was considered indicative of cognitive impairment.

Results

Serum TSPO levels were inversely correlated with MoCA scores (ρ=-0.592; P<0.001). Multivariate linear regression analysis showed that serum TSPO levels were independently associated with MoCA scores (β, -0.934; 95% confidence interval (CI), -1.412--0.455; VIF, 1.473; P<0.001). Serum TSPO levels were substantially higher in patients with cognitive impairment than in the remaining patients (median, 2.7 versus 1.6 ng/mL; P<0.001). Serum TSPO levels were linearly correlated with the risk of cognitive impairment under a restricted cubic spline (P=0.325) and independently predicted cognitive impairment (odds ratio, 1.589; 95% CI, 1.139-2.216; P=0.016). Subgroup analysis showed that the relationship between serum TSPO levels and cognitive impairment was not markedly influenced by other parameters, such as age, sex, drinking, smoking, hypertension, diabetes mellitus, body mass index, and dyslipidemia (all P for interaction > 0.05). The model, which contained serum TSPO, National Institutes of Health Stroke Scale scores and hematoma volume, performed well under the receiver operating characteristic curve, calibration curve and decision curve, and using the Hosmer-Lemeshow test. This model was validated in the validation group.

Conclusion

Serum TSPO level upon admission after ICH was independently associated with cognitive impairment, substantializing serum TSPO as a reliable predictor of post-ICH cognitive impairment.

Advances in Amyloid-β Clearance in the Brain and Periphery: Implications for Neurodegenerative Diseases

This review examines the role of impaired amyloid-β clearance in the accumulation of amyloid-β in the brain and the periphery, which is closely associated with Alzheimer's disease (AD) and cerebral amyloid angiopathy (CAA). The molecular mechanism underlying amyloid-β accumulation is largely unknown, but recent evidence suggests that impaired amyloid-β clearance plays a critical role in its accumulation. The review provides an overview of recent research and proposes strategies for efficient amyloid-β clearance in both the brain and periphery. The clearance of amyloid-β can occur through enzymatic or non-enzymatic pathways in the brain, including neuronal and glial cells, blood-brain barrier, interstitial fluid bulk flow, perivascular drainage, and cerebrospinal fluid absorption-mediated pathways. In the periphery, various mechanisms, including peripheral organs, immunomodulation/immune cells, enzymes, amyloid-β-binding proteins, and amyloid-β-binding cells, are involved in amyloid-β clearance. Although recent findings have shed light on amyloid-β clearance in both regions, opportunities remain in areas where limited data is available. Therefore, future strategies that enhance amyloid-β clearance in the brain and/or periphery, either through central or peripheral clearance approaches or in combination, are highly encouraged. These strategies will provide new insight into the disease pathogenesis at the molecular level and explore new targets for inhibiting amyloid-β deposition, which is central to the pathogenesis of sporadic AD (amyloid-β in parenchyma) and CAA (amyloid-β in blood vessels).

Matrix Metalloproteinases in Cardioembolic Stroke: From Background to Complications

Matrix metalloproteinases (MMPs) are endopeptidases participating in physiological processes of the brain, maintaining the blood-brain barrier integrity and playing a critical role in cerebral ischemia. In the acute phase of stroke activity, the expression of MMPs increase and is associated with adverse effects, but in the post-stroke phase, MMPs contribute to the process of healing by remodeling tissue lesions. The imbalance between MMPs and their inhibitors results in excessive fibrosis associated with the enhanced risk of atrial fibrillation (AF), which is the main cause of cardioembolic strokes. MMPs activity disturbances were observed in the development of hypertension, diabetes, heart failure and vascular disease enclosed in CHA₂DS₂VASc score, the scale commonly used to evaluate the risk of thromboembolic complications risk in AF patients. MMPs involved in hemorrhagic complications of stroke and activated by reperfusion therapy may also worsen the stroke outcome. In the present review, we briefly summarize the role of MMPs in the ischemic stroke with particular consideration of the cardioembolic stroke and its complications. Moreover, we discuss the genetic background, regulation pathways, clinical risk factors and impact of MMPs on the clinical outcome.

The Role of Extracellular Matrix in Human Neurodegenerative Diseases

The dense neuropil of the central nervous system leaves only limited space for extracellular substances free. The advent of immunohistochemistry, soon followed by advanced diagnostic tools, enabled us to explore the biochemical heterogeneity and compartmentalization of the brain extracellular matrix in exploratory and clinical research alike. The composition of the extracellular matrix is critical to shape neuronal function; changes in its assembly trigger or reflect brain/spinal cord malfunction. In this study, we focus on extracellular matrix changes in neurodegenerative disorders. We summarize its phenotypic appearance and biochemical characteristics, as well as the major enzymes which regulate and remodel matrix establishment in disease. The specifically built basement membrane of the central nervous system, perineuronal nets and perisynaptic axonal coats can protect neurons from toxic agents, and biochemical analysis revealed how the individual glycosaminoglycan and proteoglycan components interact with these molecules. Depending on the site, type and progress of the disease, select matrix components can either proactively trigger the formation of disease-specific harmful products, or reactively accumulate, likely to reduce tissue breakdown and neuronal loss. We review the diagnostic use and the increasing importance of medical screening of extracellular matrix components, especially enzymes, which informs us about disease status and, better yet, allows us to forecast illness.