Alzheimer’s disease (AD), a primary cause of dementia in the aging population, is characterized by extracellular amyloid-beta peptides aggregation, intracellular deposits of hyperphosphorylated tau, neurodegeneration and glial activation in the brain. It is commonly thought that the lack of early diagnostic criteria is among the main causes of pharmacological therapy and clinical trials failure; therefore, the actual challenge is to define new biomarkers and non-invasive technologies to measure neuropathological changes in vivo at pre-symptomatic stages. Recent evidences obtained from human samples and mouse models indicate the possibility to detect protein aggregates and other pathological features in the retina, paving the road for non-invasive rapid detection of AD biomarkers. Here, we report the presence of amyloid beta plaques, tau tangles, neurodegeneration and detrimental astrocyte and microglia activation according to a disease associated microglia phenotype (DAM). Thus, we propose the human retina as a useful site for the detection of cellular and molecular changes associated with Alzheimer’s disease.

Here we report on the development of a breakthrough microfluidic human in vitro cerebrovascular barrier (CVB) model featuring stem cell-derived brain-like endothelial cells (BLECs) and nanoporous silicon nitride (NPN) membranes (µSiM-CVB). The nanoscale thinness of NPN membranes combined with their high permeability and optical transparency makes them an ideal scaffold for the assembly of an in vitro microfluidic model of the blood–brain barrier (BBB) featuring cellular elements of the neurovascular unit (NVU). Dual-chamber devices divided by NPN membranes yield tight barrier properties in BLECs and allow an abluminal pericyte-co-culture to be replaced with pericyte-conditioned media. With the benefit of physiological flow and superior imaging quality, the µSiM-CVB platform captures each phase of the multi-step T-cell migration across the BBB in live cell imaging. The small volume of <100 µL of the µSiM-CVB will enable in vitro investigations of rare patient-derived immune cells with the human BBB. The µSiM-CVB is a breakthrough in vitro human BBB model to enable live and high-quality imaging of human immune cell interactions with the BBB under physiological flow. We expect it to become a valuable new tool for the study of cerebrovascular pathologies ranging from neuroinflammation to metastatic cancer.

Multiple sclerosis (MS) is the most common inflammatory disorder of the central nervous system (CNS) in young adults. When MS is not treated, it leads to irreversible and severe disability. The etiology of MS and its pathogenesis are not fully understood. The recent discovery that MS-associated genetic variants code for molecules related to the function of specific immune cell subsets is consistent with the concept of MS as a prototypic, Tcell-mediated autoimmune disease targeting the CNS. While the therapeutic efficacy of the currently available immunomodulatory therapies further strengthen this concept, differences observed in responses to MS treatment as well as additional clinical and imagingobservations have also shown that the autoimmune pathogenesis underlying MS is much more complex than previously thought. There is therefore an unmet need for continued detailed phenotypic and functional analysis of disease-relevant adaptive immune cells and tissues directly derived from MS patients to unravel the immune etiology of MS in its entire complexity. In this review, we will discuss the currently available MS treatment options and approved drugs, including how they have contributed to the understanding of the immune pathology of this autoimmune disease.Keywords: Autoantibodies r Autoimmune pathogenesis r Autoimmunity r Autoreactive B cells r Autoreactive T cells r Experimental autoimmune encephalomyelitis r Multiple sclerosis r Treatment Introduction-MS as an autoimmune diseaseMS is considered a prototypic organ-specific autoimmune disease targeting the CNS with inflammatory lesions, demyelination, axonal/neuronal damage, and metabolic changes [1,2]. Relapsing-remitting and secondary progressive MS (RRMS, SPMS) are the two most frequent forms of MS, which often affect young adults between 20 and 40 years of age, and women three times more often than men [3]. Typical clinical signs include temporary loss of vision, sensory and motor problems, but also fatigue, neurocognitive changes, and impairment of bladder, bowel, and Correspondence: Britta Engelhardt ; Roland Martin e-mail: bengel@tki.unibe.ch; roland.martin@usz.ch sexual functions. During the relapsing-remitting phase neurological deficits, which occur in bouts and may last from days to a few weeks, usually disappear again, but after several years, disability gradually builds up. Depending on the individual course this secondary progressive disease with continuously increasing disability may never set in, but often starts after 15-20 years of RRMS. In a small percentage of patients such a progressive course is seen from the beginning, which is referred to as primary progressive MS (PPMS) and seen in females and males with equal frequency [3].Evidence for an autoimmune pathogenesis of MS was shown in its animal model, experimental autoimmune encephalomyelitis (EAE) (summarized in [4,5] Treatments of MSAs already noted above, the various treatments of MS deserve particular mentioning not only because they have changed clinical practice and can be considered ...

Glioblastoma multiforme (GBM) is a diffuse brain tumor characterized by high infiltration in the brain parenchyma rendering the tumor difficult to eradicate by neurosurgery. Efforts to identify molecular targets involved in the invasive behavior of GBM suggested ion channel inhibition as a promising therapeutic approach. To determine if the Ca2+-dependent K+ channel KCa3.1 could represent a key element for GBM brain infiltration, human GL-15 cells were xenografted into the brain of SCID mice that were then treated with the specific KCa3.1 blocker TRAM-34 (1-((2-chlorophenyl) (diphenyl)methyl)-1H-pyrazole). After 5 weeks of treatment, immunofluorescence analyses of cerebral slices revealed reduced tumor infiltration and astrogliosis surrounding the tumor, compared with untreated mice. Significant reduction of tumor infiltration was also observed in the brain of mice transplanted with KCa3.1-silenced GL-15 cells, indicating a direct effect of TRAM-34 on GBM-expressed KCa3.1 channels. As KCa3.1 channels are also expressed on microglia, we investigated the effects of TRAM-34 on microglia activation in GL-15 transplanted mice and found a reduction of CD68 staining in treated mice. Similar results were observed in vitro where TRAM-34 reduced both phagocytosis and chemotactic activity of primary microglia exposed to GBM-conditioned medium. Taken together, these results indicate that KCa3.1 activity has an important role in GBM invasiveness in vivo and that its inhibition directly affects glioma cell migration and reduces astrocytosis and microglia activation in response to tumor-released factors. KCa3.1 channel inhibition therefore constitutes a potential novel therapeutic approach to reduce GBM spreading into the surrounding tissue.

The activation of ion channels is crucial during cell movement, including glioblastoma cell invasion in the brain parenchyma. In this context, we describe for the first time the contribution of intermediate conductance Ca(2+)-activated K (IK(Ca)) channel activity in the chemotactic response of human glioblastoma cell lines, primary cultures, and freshly dissociated tissues to CXC chemokine ligand 12 (CXCL12), a chemokine whose expression in glioblastoma has been correlated with its invasive capacity. We show that blockade of the IK(Ca) channel with its specific inhibitor 1-[(2-chlorophenyl) diphenylmethyl]-1H-pyrazole (TRAM-34) or IK(Ca) channel silencing by short hairpin RNA (shRNA) completely abolished CXCL12-induced cell migration. We further demonstrate that this is not a general mechanism in glioblastoma cell migration since epidermal growth factor (EGF), which also activates IK(Ca) channels in the glioblastoma-derived cell line GL15, stimulate cell chemotaxis even if the IK(Ca) channels have been blocked or silenced. Furthermore, we demonstrate that both CXCL12 and EGF induce Ca(2+) mobilization and IK(Ca) channel activation but only CXCL12 induces a long-term upregulation of the IK(Ca) channel activity. Furthermore, the Ca(2+)-chelating agent BAPTA-AM abolished the CXCL12-induced, but not the EGF-induced, glioblastoma cell chemotaxis. In addition, we demonstrate that the extracellular signal-regulated kinase (ERK)1/2 pathway is only partially implicated in the modulation of CXCL12-induced glioblastoma cell movement, whereas the phosphoinositol-3 kinase (PI3K) pathway is not involved. In contrast, EGF-induced glioblastoma migration requires both ERK1/2 and PI3K activity. All together these findings suggest that the efficacy of glioblastoma invasiveness might be related to an array of nonoverlapping mechanisms activated by different chemotactic agents.

Microglia cells are active players in regulating synaptic development and plasticity in the brain. However, how they influence the normal functioning of synapses is largely unknown. In this study, we characterized the effects of pharmacological microglia depletion, achieved by administration of PLX5622, on hippocampal CA3‐CA1 synapses of adult wild type mice. Following microglial depletion, we observed a reduction of spontaneous and evoked glutamatergic activity associated with a decrease of dendritic spine density. We also observed the appearance of immature synaptic features and higher levels of plasticity. Microglia depleted mice showed a deficit in the acquisition of the Novel Object Recognition task. These events were accompanied by hippocampal astrogliosis, although in the absence ofneuroinflammatory condition. PLX‐induced synaptic changes were absent in Cx3cr1−/− mice, highlighting the role of CX3CL1/CX3CR1 axis in microglia control of synaptic functioning. Remarkably, microglia repopulation after PLX5622 withdrawal was associated with the recovery of hippocampal synapses and learning functions. Altogether, these data demonstrate that microglia contribute to normal synaptic functioning in the adult brain and that their removal induces reversible changes in organization and activity of glutamatergic synapses.

Mutations in the RNA-binding protein (RBP) FUS have been genetically associated with the motoneuron disease amyotrophic lateral sclerosis (ALS). Using both human induced pluripotent stem cells and mouse models, we found that FUS-ALS causative mutations affect the activity of two relevant RBPs with important roles in neuronal RNA metabolism: HuD/ELAVL4 and FMRP. Mechanistically, mutant FUS leads to upregulation of HuD protein levels through competition with FMRP for HuD mRNA 3’UTR binding. In turn, increased HuD levels overly stabilize the transcript levels of its targets, NRN1 and GAP43. As a consequence, mutant FUS motoneurons show increased axon branching and growth upon injury, which could be rescued by dampening NRN1 levels. Since similar phenotypes have been previously described in SOD1 and TDP-43 mutant models, increased axonal growth and branching might represent broad early events in the pathogenesis of ALS.

Background: The brain barriers establish compartments in the central nervous system (CNS) that significantly differ in their communication with the peripheral immune system. In this function they strictly control T-cell entry into the CNS. T cells can reach the CNS by either crossing the endothelial blood-brain barrier (BBB) or the epithelial bloodcerebrospinal fluid barrier (BCSFB) of the choroid plexus (ChP). Objective: Analysis of the cellular and molecular mechanisms involved in the migration of different human CD4 + T-cell subsets across the BBB versus the BCSFB. Methods: Human in vitro models of the BBB and BCSFB were employed to study the migration of circulating and CNS-entry experienced CD4 + T helper cell subsets (Th1, Th1*, Th2, Th17) across the BBB and BCSFB under inflammatory and non-inflammatory conditions in vitro. Results: While under non-inflammatory conditions Th1* and Th1 cells preferentially crossed the BBB, under inflammatory conditions the migration rate of all Th subsets across the BBB was comparable. The migration of all Th subsets across the BCSFB from the same donor was 10-to 20-fold lower when compared to their migration across the BBB. Interestingly, Th17 cells preferentially crossed the BCSFB under both, non-inflamed and inflamed conditions. Barriercrossing experienced Th cells sorted from CSF of MS patients showed migratory characteristics indistinguishable from those of circulating Th cells of healthy donors. All Th cell subsets could additionally cross the BCSFB from the CSF to ChP stroma side. T-cell migration across the BCSFB involved epithelial ICAM-1 irrespective of the direction of migration. Conclusions: Our observations underscore that different Th subsets may use different anatomical routes to enter the CNS during immune surveillance versus neuroinflammation with the BCSFB establishing a tighter barrier for T-cell entry into the CNS compared to the BBB. In addition, CNS-entry experienced Th cell subsets isolated from the CSF of MS patients do not show an increased ability to cross the brain barriers when compared to circulating Th cell subsets from healthy donors underscoring the active role of the brain barriers in controlling T-cell entry into the CNS. Also we identify ICAM-1 to mediate T cell migration across the BCSFB.