MCC950 Inhibits NLRP3 Inflammasome and Alleviates Axonal Injures in Early Stages of Diffuse Axonal Injury in Rats.

Increasing evidence has revealed that neuroinflammation plays a pivotal role in axonal injures. Nucleotide oligomerization domain (NOD)-like receptor protein (NLRP3) inflammasome is reported to be widely involved with the pathology of central nervous system disorders. But the role of NLRP3 in diffuse axonal injury (DAI) are rarely reported. The purpose of this study was to investigate the expression of NLRP3 after diffuse axonal injury and the role of NLRP3 in axonal injures. The lateral head rotation device was used to establish DAI model of rats. Immunohistochemical staining for ß-amyloid precursor protein and Bielschowsky silver staining were used to assess axonal injures and axonal loss. Terminal Deoxynucleotidyl Transferase-Mediated Digoxigenin-dUTP-Biotin Nick-End Labelling Assay was used to detect cell apoptosis. Brain water content was used to assess cerebral edema and the modified Neurologic Severity Score was used to assess the neurological deficits. Components of NLRP3 inflammasome, such as NLRP3, apoptosis-associated speck-like (ASC) adapter protein and caspase-1, and pro-inflammatory cytokines, for example IL-18 and IL-1ß, were over-expressed in early stages of DAI. MCC950, a selective small-molecule inhibitor of NLRP3 inflammasome, inhibited the over-expression of NLRP3 inflammasome and pro-inflammatory cytokines after DAI. MCC950 alleviated axonal injures and cell apoptosis. MCC950 also decreased brain water content and alleviated neurologic deficits 1 day and 3 days after DAI but not 7 days after DAI. These results suggest that MCC950 treatment in the early stages of DAI has a time limiting effect in preventing from axonal injuries and neurological deficits, and that NLRP3 inflammasome plays an important role in axonal injures and may be a potential candidate for axonal injures following DAI.

The Sustained Release of Tafluprost with a Drug Delivery System Prevents the Axonal Injury-induced Loss of Retinal Ganglion Cells in Rats.

PURPOSE: To investigated whether a new drug delivery system (DDS) could enable the controlled release of tafluprost and suppress retinal ganglion cell (RGC) death in rats after optic nerve transection (ONT). METHODS: A DDS containing 0.04%, 0.20% or 1.00% tafluprost, or vehicle, was injected intravitreally in 8-12-week-old male Sprague-Dawley rats 7 days before ONT, and the retinas were extracted 7 days after ONT. For comparison, eye drops containing 0.0015% tafluprost or vehicle were used once a day. The extracted retinas were analyzed with liquid chromatography-tandem mass spectrometry, immunohistochemistry and western blotting. RESULTS: The level of tafluprost acid in the groups that received the 0.20% and 1.00% tafluprost DDSs was stable, and higher than the maximum concentration in the eye drop group, even after 14 days. In the retinas treated with the 1.00% tafluprost DDS, the active form of the drug had a high concentration (~50 times higher than eye drops), but no significant IOP difference compared with its vehicle in this study. The 1.00% tafluprost DDS group also had less cleaved α-fodrin and fewer c-Jun-positive cells than the vehicle DDS group. CONCLUSIONS: This study found that a newly developed DDS allowed the controlled release of tafluprost and prevented the loss of RGCs after ONT IOP independently. The duration of drug action on the target site was longer with a tafluprost DDS than with topical instillation and should therefore reduce problems related to lack of patient compliance. This system may also enable new treatments to prevent RGC degeneration in diseases such as glaucoma.

In vivo transduction of neurons with TAT-UCH-L1 protects brain against controlled cortical impact injury.

Many mechanisms or pathways are involved in secondary post-traumatic brain injury, such as the ubiquitin-proteasome pathway (UPP), axonal degeneration and neuronal cell apoptosis. UCH-L1 is a protein that is expressed in high levels in neurons and may have important roles in the UPP, autophagy and axonal integrity. The current study aims to evaluate the role of UCH-L1 in post-traumatic brain injury (TBI) and its potential therapeutic effects. A novel protein was constructed that fused the protein transduction domain (PTD) of trans-activating transduction (TAT) protein with UCH-L1 (TAT-UCH-L1) in order to promote neuronal transduction. The TAT-UCH-L1 protein was readily detected in brain by immunoblotting and immunohistochemistry after i.p. administration in mice. TBI was induced in mice using the controlled cortical impact (CCI) model. TAT-UCH-L1 treatment significantly attenuated K48-linkage polyubiquitin (polyUb)-protein accumulation in hippocampus after CCI compared to vehicle controls, but had no effects on K65-linkage polyUb-protein. TAT-UCH-L1 treatment also attenuated expression of Beclin-1 and LC3BII after CCI. TAT-UCH-L1-treated mice had significantly increased spared tissue volumes and increased survival of CA3 neurons 21 d after CCI compared to control vehicle-treated mice. Axonal injury, detected by APP immunohistochemistry, was reduced in thalamus 24 h and 21 d after CCI in TAT-UCH-L1-treated mice. These results suggest that TAT-UCH-L1 treatment improves function of the UPP and decreases activation of autophagy after CCI. Furthermore, TAT-UCH-L1 treatment also attenuates axonal injury and increases hippocampal neuronal survival after CCI. Taken together these results suggest that UCH-L1 may play an important role in the pathogenesis of cell death and axonal injury after TBI.

Asociación entre el déficit de vitamina D y los potenciales evocados visuales en la esclerosis múltiple / Relationship between vitamin D deficiency and visually evoked potentials in multiple sclerosis

OBJETIVO: Evaluar la posible relación entre los niveles séricos de 25-OH-vitamina D y los potenciales evocados visuales (PEV) de los pacientes con esclerosis múltiple (EM) residentes en la zona sur de Gran Canaria. MATERIAL Y MÉTODOS: Se incluyó a 49 pacientes con EM. Se les realizó determinación de 25-OH-vitamina D, PEV, exploración neurológica para determinar la discapacidad y se recogieron variables clínicas tales como el antecedente de neuritis óptica. RESULTADOS: El valor medio de 25-OH-vitamina D de los pacientes fue de 28,1 ± 9,5 ng/ml, la latencia de los PEV fue de 119,1 ± 23,2 ms y la amplitud de 8,5 ± 4,4 μV. Los pacientes con niveles normales de 25-OH-vitamina D tuvieron mayor número de brotes en el año previo al estudio (p = 0,049) y aquellos con déficit de vitamina D y neuritis óptica previa no presentaron reducción de la amplitud de los PEV (p = 0,006). CONCLUSIÓN: Los pacientes con déficit de vitamina D tienen menor actividad clínica de la EM y no presentan afectación axonal en PEV tras haber sufrido neuritis óptica. Estas asociaciones, aunque estadísticamente significativas, no parecen clínicamente plausibles, por lo que sería preciso realizar nuevos estudios que intentasen confirmar esta posible asociación

OBJECTIVE: To evaluate the possible relationship between serum 25-OH vitamin D levels and visually evoked potentials (VEP) in patients with multiple sclerosis (MS), residents in the south zone of Gran Canaria. MATERIAL AND METHODS: The study included 49 patients with MS, on whom 25-OH-vitamin D was determined, along with VEP, and a neurological examination to determine incapacity. Clinical variables, such as a history of optic neuritis were recorded. RESULTS: The mean value of 25-OH-vitamin D of the patients was 28.1 ± 9.5 ng/ml. The VEP latency was 119.1 ± 23.2 ms and the amplitude, 8.5 ± 4.4 μV. Patients with a higher 25-OH-vitamin D had a greater number of outbreaks in the year prior to the study (P=.049), and those with vitamin D deficiency and previous optic neuritis showed no reduction in the amplitude of the VEP (P=.006). CONCLUSION: Patients with vitamin D deficiency have lower clinical activity of the MS and show no axonal involvement in VEP after having suffered optic neuritis. These relationships, although statistically significant, do not seem clinically plausible, thus new studies are needed to try and confirm this possible relationship

Angular Impact Mitigation system for bicycle helmets to reduce head acceleration and risk of traumatic brain injury.

Angular acceleration of the head is a known cause of traumatic brain injury (TBI), but contemporary bicycle helmets lack dedicated mechanisms to mitigate angular acceleration. A novel Angular Impact Mitigation (AIM) system for bicycle helmets has been developed that employs an elastically suspended aluminum honeycomb liner to absorb linear acceleration in normal impacts as well as angular acceleration in oblique impacts. This study tested bicycle helmets with and without AIM technology to comparatively assess impact mitigation. Normal impact tests were performed to measure linear head acceleration. Oblique impact tests were performed to measure angular head acceleration and neck loading. Furthermore, acceleration histories of oblique impacts were analyzed in a computational head model to predict the resulting risk of TBI in the form of concussion and diffuse axonal injury (DAI). Compared to standard helmets, AIM helmets resulted in a 14% reduction in peak linear acceleration (p<0.001), a 34% reduction in peak angular acceleration (p<0.001), and a 22-32% reduction in neck loading (p<0.001). Computational results predicted that AIM helmets reduced the risk of concussion and DAI by 27% and 44%, respectively. In conclusion, these results demonstrated that AIM technology could effectively improve impact mitigation compared to a contemporary expanded polystyrene-based bicycle helmet, and may enhance prevention of bicycle-related TBI. Further research is required.

Internal jugular vein compression mitigates traumatic axonal injury in a rat model by reducing the intracranial slosh effect.

BACKGROUND: Traumatic brain injury (TBI) remains a devastating condition for which extracranial protection traditionally has been in the form of helmets, which largely fail to protect against intracranial injury. OBJECTIVE: To determine whether the pathological outcome after traumatic brain injury can be improved via slosh mitigation by internal jugular vein (IJV) compression. METHODS: Two groups of 10 adult male Sprague-Dawley rats were subjected to impact-acceleration traumatic brain injury. One group underwent IJV compression via application of a collar before injury; the second group did not. Intracranial pressure and intraocular pressure were measured before and after IJV compression to assess collar performance. All rats were killed after a 7-day recovery period, and brainstem white matter tracts underwent fluorescent immunohistochemical processing and labeling of ß-amyloid precursor protein, a marker of axonal injury. Digital imaging and statistical analyses were used to determine whether IJV compression resulted in a diminished number of injured axons. RESULTS: Compression of the IJV resulted in an immediate 30% increase in intraocular and intracranial pressures. Most notably, IJV compression resulted in > 80% reduction in the number of amyloid precursor protein-positive axons as indicated by immunohistochemical analysis. CONCLUSION: Using a standard acceleration-deceleration laboratory model of mild traumatic brain injury, we have shown successful prevention of axonal injury after IJV compression as indicated by immunohistochemical staining of amyloid precursor protein. We argue that IJV compression reduces slosh-mediated brain injury by increasing intracranial blood volume, which can be indirectly measured by intracranial and intraocular pressures.

Administration of the immunophilin ligand FK506 differentially attenuates neurofilament compaction and impaired axonal transport in injured axons following diffuse traumatic brain injury.

Traumatic axonal injury (TAI) following traumatic brain injury (TBI) remains a clinical problem for which no effective treatment exists. TAI was thought to involve intraaxonal changes that universally led to impaired axonal transport (IAT), disconnection and axonal bulb formation. However, recent, immunocytochemical studies employing antibodies to amyloid precursor protein (APP), a marker of IAT and antibodies to neurofilament compaction (NFC), RM014, demonstrated that NFC typically occurs independent of IAT, indicating the existence of different populations of damaged axons. FK506 administration has been shown to attenuate IAT. However, in light of the above, the ability of FK506 to attenuate axonal damage demonstrating NFC requires evaluation. The current study explored the potential of FK506 to attenuate both populations of damaged axons. Rats were administered FK506 (3 mg/kg) or vehicle 30 min preinjury. Three hours post-TBI, tissue was prepared for the visualization of TAI using antibodies targeting IAT (APP) or NFC (RMO14) or a combined labeling strategy. Confirming previous reports, FK506 treatment reduced the number of axons demonstrating IAT in the CSpT, from 411 +/- 54.70 to 91.00 +/- 33.87 (P

Ultrastructural observation of effect of moderate hypothermia on axonal damage in an animal model of diffuse axonal injury.

OBJECTIVE: To investigate the effect of moderate hypothermia on responses of axonal cytoskeleton to axonal injury in the acute stage of injury. METHODS: Of fifteen adult guinea pigs, twelve animals were subjected to stretch injury to the right optic nerves and divided into the normothermic group (n = 6) in which the animal's core temperature was maintained at 36.0-37.5 degrees C and the hypothermia group (n = 6) in which the core temperature was reduced to 32.0-32.5 degrees C after stretch injury. Remaining three animals sustained no injury to the right optic nerves and served as control group. Half of injured animals (n = 3) of either normothermic group or hypothermic group were killed at either 2 hours or 4 hours after injury. The ultrastructural changes of axonal cytoskeleton of the right optic nerve fibers from the animals were examined under a transmission electron microscope and analyzed by quantitative analysis with a computer image analysis system. RESULTS: At 2 hours after stretch injury, there was a significant reduction in the mean number of microtubules (P < 0.001), and a significant increase in the mean intermicrotubule spacing (P < 0.05 or P < 0.01) in axons of all sizes in normothermic animals. The mean number of neurofilaments also decreased statistically (P < 0.01) in large and medium subgroups of axons in the same experimental group at 2 hours. By 4 hours, the large subgroup of axons in normothermic animals still demonstrated a significant decline in the mean number of microtubules (P < 0.01) and an increase in the mean intermicrotubule spacing (P < 0.05), while the medium and small subgroups of axons displayed a significant increase in the mean number of neurofilaments (P < 0.05) and reduction in the mean interneurofilament spacing (P < 0.05). On the contrary, either the mean number of microtubules and the mean intermicrotubule spacing, or the mean number of neurofilaments and interneurofilament spacing in axons of all sizes in hypothermic stretch-injured animals was not significant different from the mean values of sham-operated animals. CONCLUSIONS: Posttraumatic moderate hypothermia induced immediately after axonal injury results in substantial protection of axonal cytoskeleton and ameliorates axonal damage.