Adhesion molecules close homolog of L1 and tenascin-C affect blood–spinal cord barrier repair

The extracellular matrix glycoprotein tenascin-C and matrix metalloproteinases modify cerebellar structural plasticity by exposure to an enriched environment

The importance of the extracellular matrix (ECM) glycoprotein tenascin-C (TnC) and the ECM degrading enzymes, matrix metalloproteinases (MMPs) -2 and -9, in cerebellar histogenesis is well established. This study aimed to examine whether there is a functional relationship between these molecules in regulating structural plasticity of the lateral deep cerebellar nucleus. To this end, starting from postnatal day 21, TnC- or MMP-9-deficient mice were exposed to an enriched environment (EE). We show that 8 weeks of exposure to EE leads to reduced lectin-based staining of perineuronal nets (PNNs), reduction in the size of GABAergic and increase in the number and size of glutamatergic synaptic terminals in wild-type mice. Conversely, TnC-deficient mice showed reduced staining of PNNs compared to wild-type mice maintained under standard conditions, and exposure to EE did not further reduce, but even slightly increased PNN staining. EE did not affect the densities of the two types of synaptic terminals in TnC-deficient mice, while the size of inhibitory, but not excitatory synaptic terminals was increased. In the time frame of 4-8 weeks, MMP-9, but not MMP-2, was observed to influence PNN remodeling and cerebellar synaptic plasticity as revealed by measurement of MMP-9 activity and colocalization with PNNs and synaptic markers. These findings were supported by observations on MMP-9-deficient mice. The present study suggests that TnC contributes to the regulation of structural plasticity in the cerebellum and that interactions between TnC and MMP-9 are likely to be important for these processes to occur.

Tenascin-C deficiency ameliorates Alzheimer's disease-related pathology in mice

Alzheimer's disease (AD) is a neurodegenerative disease characterized by deposits of amyloid β peptide (Aβ) and microglia-driven inflammatory activation. Tenascin-C (tnc) is an extracellular matrix protein that is upregulated in inflammation and induces further inflammatory responses. We hypothesized that tnc contributes to the inflammatory pathology in AD. Using real-time polymerase chain reaction, we observed that tnc gene transcription was upregulated in cultured microglia after Aβ challenge and in the brain of an AD mouse model that overexpresses mutated amyloid precursor protein (APP) in neural cells. By cross-breeding APP-transgenic mice and tenascin-C-deficient mice, we demonstrated using real-time polymerase chain reaction, Western blot analysis, enzyme-linked immunosorbent assay, and immunohistochemistry that tnc deficiency reduces pro- but enhances anti-inflammatory activation in the mutated APP-transgenic mouse brain, associated with a reduced cerebral Aβ load and higher levels of the postsynaptic density protein 95. Thus, our study indicates that functional inhibition of tnc exerts beneficial effects on AD pathogenesis, suggesting a potential for tnc as a new therapeutic target in AD.

Management strategies for acute spinal cord injury: current options and future perspectives

PURPOSE OF REVIEW

Spinal cord injury is a devastating acute neurological condition with loss of function and poor long-term prognosis. This review summarizes current management strategies and innovative concepts on the horizon.

RECENT FINDINGS

The routine use of steroids in patients with spinal cord injuries has been largely abandoned and considered a 'harmful standard of care'. Prospective trials have shown that early spine stabilization within 24  h results in decreased secondary complication rates. Neuronal plasticity and axonal regeneration in the adult spinal cord are limited due to myelin-associated inhibitory molecules, such as Nogo-A. The experimental inhibition of Nogo-A ameliorates axonal sprouting and functional recovery in animal models.

SUMMARY

General management strategies for acute spinal cord injury consist of protection of airway, breathing, oxygenation and control of blood loss with maintenance of blood pressure. Unstable spine fractures should be stabilized early to allow unrestricted mobilization of patients with spinal cord injuries and to decrease preventable complications. Steroids are largely considered obsolete and have been abandoned in clinical guidelines. Nogo-A represents a promising new pharmacological target to promote sprouting of injured axons and restore function. Prospective clinical trials of Nogo-A inhibition in patients with spinal cord injuries are currently under way.