Benjamin V. Ineichen

Outflow of cerebrospinal fluid is predominantly through lymphatic vessels and is reduced in aged mice

Cerebrospinal fluid (CSF) has been commonly accepted to drain through arachnoid projections from the subarachnoid space to the dural venous sinuses. However, a lymphatic component to CSF outflow has long been known. Here, we utilize lymphatic-reporter mice and high-resolution stereomicroscopy to characterize the anatomical routes and dynamics of outflow of CSF. After infusion into a lateral ventricle, tracers spread into the paravascular spaces of the pia mater and cortex of the brain. Tracers also rapidly reach lymph nodes using perineural routes through foramina in the skull. Using noninvasive imaging techniques that can quantify the transport of tracers to the blood and lymph nodes, we find that lymphatic vessels are the major outflow pathway for both large and small molecular tracers in mice. A significant decline in CSF lymphatic outflow is found in aged compared to young mice, suggesting that the lymphatic system may represent a target for age-associated neurological conditions.It is believed that the bulk of cerebrospinal fluid (CSF) drains through arachnoid projections from the subarachnoid space to the dural venous sinuses. Here the authors show that the major outflow pathway for CSF in mice are lymphatic vessels and that this drainage decreases as the mice age.

Neurogenic lower urinary tract dysfunction (NLUTD) in patients with spinal cord injury: long-term urodynamic findings

To investigate long‐term urodynamic findings in patients with spinal cord injury (SCI) with neurogenic lower urinary tract dysfunction (NLUTD).

The variant methylenetetrahydrofolate reductase c.1298A > C (p.E429A) is associated with multiple sclerosis in a German case-control study.

Multiple sclerosis (MS) is an inflammatory demyelinating autoimmune disease of the central nervous system. We investigated the association of two missense variants of the MTHFR gene, i.e. MTHFR c.677C>T (p.A222V) and c.1298A>C (p.E429A), in 138 patients with clinically definite multiple sclerosis of relapsing-remitting course and 138 age- and gender-matched healthy controls. No significant differences were found in the frequency of the MTHFR c.677C>T polymorphism between MS patients and healthy controls. However, the genotype frequencies of the missense variant MTHFR c.1298A>C were significantly different between patients (AA/AC/CC: 0.34/0.55/0.11) and controls (0.52/0.36/0.12; Pearsons chi(2)=11.1; p=0.004). These results suggest that homozygosity for the A allele of MTHFR c.1298A>C may be protective against the incidence of MS. If confirmed in an independent study sample, the underlying mechanisms should be investigated, which may lead to novel insights in biochemical factors influencing the aetiology and pathophysiology of MS.

Hyperhomocysteinemia in Alzheimer's disease: the hen and the egg?

Hyperhomocysteinemia is associated with Alzheimers disease (AD). The causality of this association is controversial. In this study we tested the effect of a hyperhomocysteinemia-inducing diet in the ArcAβ transgenic AD mouse model. At 14 months of age, the hyperhomocysteinemia-inducing diet yielded higher plasma homocysteine levels in ArcAβ mice compared with wild-type mice. Levels of plasma 5-methyltetrahydrofolate (5-MTHF) in 14-month-old mice on hyperhomocysteinemia-inducing diet were lower in the transgenic than in the wild-type mice. The folate derivate 5-MTHF serves as cofactor in homocysteine metabolism. Oxidative stress, which occurs in the course of disease in the ArcAβ mice, consumes 5-MTHF. Thus, the transgenic mice may plausibly be more vulnerable to 5-MTHF-depleting effects of hyperhomocysteinemia and more vulnerable to hyperhomocysteinemia-inducing diet. This argues that AD pathology predisposes to hyperhomocysteinemia, i.e., as a facultative consequence of AD. However, we also observed that dietary-induced folate reduction and homocysteine increase was associated with an increase of plasma (young animals) and brain (older animals) amyloid-β concentrations. This suggests that the hyperhomocysteinemia-inducing diet worsened pathology in the transgenic mice. In conclusion, this data may argue that folate reduction and hyperhomocysteinemia may contribute to neurodegeneration and may also be triggered by neurodegenerative processes, i.e., represent both a cause and a consequence of neurodegeneration. Such a vicious cycle may be breakable by dietary or supplementation strategies increasing the availability of 5-MTHF.

Direct, long-term intrathecal application of therapeutics to the rodent CNS

Systemic application of therapeutics to the CNS tissue often results in subtherapeutic drug levels, because of restricted and selective penetration through the blood–brain barrier (BBB). Here, we give a detailed description of a standardized technique for intrathecal drug delivery in rodents, analogous to the technique used in humans. The intrathecal drug delivery method bypasses the BBB and thereby offers key advantages over oral or intravenous administration, such as maximized local drug doses with minimal systemic side effects. We describe how to deliver antibodies or drugs over several days or weeks from a s.c. minipump and a fine catheter inserted into the subdural space over the spinal cord (20 min operative time) or into the cisterna magna (10 min operative time). Drug levels can be sampled by quick and minimally invasive cerebrospinal fluid (CSF) collection from the cisterna magna (5 min procedure time). These techniques enable targeted application of any compound to the CNS for therapeutic studies in a wide range of CNS disease rodent models. Basic surgery skills are helpful for carrying out the procedures described in this protocol.

Pharmacological recanalization therapy in acute ischemic stroke - evolution, current state and perspectives of intravenous and intra-arterial thrombolysis.

Stroke ranges third in mortality in industrialized nations and is the leading cause of disability in older people. Ischemic stroke following thrombotic or embolic vessel occlusion accounts for more than 80% of cerebrovascular events. Immediate restoration of cerebral blood flow is crucial in order to salvage brain tissue. Experimental thrombolytic treatment was introduced into the clinical setting in the late 1950s and required more than 30 years of intense research till its breakthrough and subsequent routine clinical use by the presentation of the NINDS trial results in 1995. To date, intravenous thrombolysis with tissue plasminogen activator up to 4.5 h after symptom onset is the only proven reperfusion therapy for acute ischemic stroke. In this review, we summarize the evolution of intravenous and intra-arterial pharmacological recanalization therapies in acute ischemic stroke and present current clinical practice as well as its promising perspectives.

Optogenetically stimulating intact rat corticospinal tract post-stroke restores motor control through regionalized functional circuit formation

Current neuromodulatory strategies to enhance motor recovery after stroke often target large brain areas non-specifically and without sufficient understanding of their interaction with internal repair mechanisms. Here we developed a novel therapeutic approach by specifically activating corticospinal circuitry using optogenetics after large strokes in rats. Similar to a neuronal growth-promoting immunotherapy, optogenetic stimulation together with intense, scheduled rehabilitation leads to the restoration of lost movement patterns rather than induced compensatory actions, as revealed by a computer vision-based automatic behavior analysis. Optogenetically activated corticospinal neurons promote axonal sprouting from the intact to the denervated cervical hemi-cord. Conversely, optogenetically silencing subsets of corticospinal neurons in recovered animals, results in mistargeting of the restored grasping function, thus identifying the reestablishment of specific and anatomically localized cortical microcircuits. These results provide a conceptual framework to improve established clinical techniques such as transcranial magnetic or transcranial direct current stimulation in stroke patients.Existing methods to improve motor function after stroke include non-specific neuromodulatory approaches. Here the authors use an automated method of analysis of reaching behaviour in rodents to show that optogenetic stimulation of intact corticospinal tract fibres leads to restoration of prior motor functions, rather than compensatory acquisition of new movements.

Cannabinoids for treating neurogenic lower urinary tract dysfunction in patients with multiple sclerosis: a systematic review and meta-analysis.

To review systematically all the available evidence on efficacy and safety of cannabinoids for treating neurogenic lower urinary tract dysfunction (NLUTD) in patients with multiple sclerosis (MS).

Nogo-A antibodies enhance axonal repair and remyelination in neuro-inflammatory and demyelinating pathology

Two hallmarks of chronic multiple sclerosis lesions are the absence of significant spontaneous remyelination and primary as well as secondary neurodegeneration. Both characteristics may be influenced by the presence of inhibitory factors preventing myelin and neuronal repair. We investigated the potential of antibodies against Nogo-A, a well-known inhibitory protein for neuronal growth and plasticity, to enhance neuronal regeneration and remyelination in two animal models of multiple sclerosis. We induced a targeted experimental autoimmune encephalomyelitis (EAE) lesion in the dorsal funiculus of the cervical spinal cord of adult rats resulting in a large drop of skilled forelimb motor functions. We subsequently observed improved recovery of forelimb function after anti-Nogo-A treatment. Anterograde tracing of the corticospinal tract revealed enhanced axonal sprouting and arborisation within the spinal cord gray matter preferentially targeting pre-motor and motor spinal cord laminae on lesion level and above in the anti-Nogo-A-treated animals. An important additional effect of Nogo-A-neutralization was enhanced remyelination observed after lysolecithin-induced demyelination of spinal tracts. Whereas remyelinated fiber numbers in the lesion site were increased several fold, no effect of Nogo-A-inhibition was observed on oligodendrocyte precursor proliferation, migration, or differentiation. Enhancing remyelination and promoting axonal regeneration and plasticity represent important unmet medical needs in multiple sclerosis. Anti-Nogo-A antibodies hold promise as a potential new therapy for multiple sclerosis, in particular during the chronic phase of the disease when neurodegeneration and remyelination failure determine disability evolution.

Genetic variants of homocysteine metabolism and multiple sclerosis: A case–control study

Methylenetetrahydrofolate reductase (MTHFR) is necessary for the synthesis of methionine and S-adenosylmethionine, which is necessary for CNS (re-)myelination. The MTHFR variant c.1298A>C was associated with the development of relapsing remitting multiple sclerosis (RRMS) in a German population. This study aimed at analyzing whether further genetic variants of methionine metabolism are associated with the development or the clinical course of RRMS. Therefore, genomic DNA of 147 serial German RRMS patients and 147 matched healthy controls was genotyped for five polymorphic variants of methionine metabolism. Statistical analyses were performed using multivariate binary and linear regression analyses. We show that the insertion allele of cystathionine beta-synthase (CBS) c.844_855ins68bp and the G-allele of reduced folate carrier 1 (RFC1) c.80G>A were associated with an earlier age of onset of MS, suggesting gene-dose effects (median age of onset in years: 25-26-32; standardized regression coefficient beta: 0.216; p=0.030, and 29-31-35 years; beta: 0.282; p=0.005, respectively). Conclusively, mutant variants of CBS and RFC1 may be associated with the age of RRMS onset. Since methionine metabolism can be manipulated by supplementation of vitamins and amino acids, our data provide a rationale for novel ideas of preventive and therapeutic strategies in RRMS.