Growth-Promoting Treatment Screening for Corticospinal Neurons in Mouse and Man.

Neurons of the central nervous system (CNS) that project long axons into the spinal cord have a poor axon regenerative capacity compared to neurons of the peripheral nervous system. The corticospinal tract (CST) is particularly notorious for its poor regeneration. Because of this, traumatic spinal cord injury (SCI) is a devastating condition that remains as yet uncured. Based on our recent observations that direct neuronal interleukin-4 (IL-4) signaling leads to repair of axonal swellings and beneficial effects in neuroinflammation, we hypothesized that IL-4 acts directly on the CST. Here, we developed a tissue culture model for CST regeneration and found that IL-4 promoted new growth cone formation after axon transection. Most importantly, IL-4 directly increased the regenerative capacity of both murine and human CST axons, which corroborates its regenerative effects in CNS damage. Overall, these findings serve as proof-of-concept that our CST regeneration model is suitable for fast screening of new treatments for SCI.

Fast direct neuronal signaling via the IL-4 receptor as therapeutic target in neuroinflammation.

Ongoing axonal degeneration is thought to underlie disability in chronic neuroinflammation, such as multiple sclerosis (MS), especially during its progressive phase. Upon inflammatory attack, axons undergo pathological swelling, which can be reversible. Because we had evidence for beneficial effects of T helper 2 lymphocytes in experimental neurotrauma and discovered interleukin-4 receptor (IL-4R) expressed on axons in MS lesions, we aimed at unraveling the effects of IL-4 on neuroinflammatory axon injury. We demonstrate that intrathecal IL-4 treatment during the chronic phase of several experimental autoimmune encephalomyelitis models reversed disease progression without affecting inflammation. Amelioration of disability was abrogated upon neuronal deletion of IL-4R. We discovered direct neuronal signaling via the IRS1-PI3K-PKC pathway underlying cytoskeletal remodeling and axonal repair. Nasal IL-4 application, suitable for clinical translation, was equally effective in improving clinical outcome. Targeting neuronal IL-4 signaling may offer new therapeutic strategies to halt disability progression in MS and possibly also neurodegenerative conditions.

The serine/threonine kinase 33 is present and expressed in palaeognath birds but has become a unitary pseudogene in neognaths about 100 million years ago.

BACKGROUND: Serine/threonine kinase 33 (STK33) has been shown to be conserved across all major vertebrate classes including reptiles, mammals, amphibians and fish, suggesting its importance within vertebrates. It has been shown to phosphorylate vimentin and might play a role in spermatogenesis and organ ontogenesis. In this study we analyzed the genomic locus and expression of stk33 in the class Aves, using a combination of large scale next generation sequencing data analysis and traditional PCR. RESULTS: Within the subclass Palaeognathae we analyzed the white-throated tinamou (Tinamus guttatus), the African ostrich (Struthio camelus) and the emu (Dromaius novaehollandiae). For the African ostrich we were able to generate a 62,778 bp long genomic contig and an mRNA sequence that encodes a protein showing highly significant similarity to STK33 proteins from other vertebrates. The emu has been shown to encode and transcribe a functional STK33 as well. For the white-throated tinamou we were able to identify 13 exons by sequence comparison encoding a protein similar to STK33 as well. In contrast, in all 28 neognath birds analyzed, we could not find evidence for the existence of a functional copy of stk33 or its expression. In the genomes of these 28 bird species, we found only remnants of the stk33 locus carrying several large genomic deletions, leading to the loss of multiple exons. The remaining exons have acquired various indels and premature stop codons. CONCLUSIONS: We were able to elucidate and describe the genomic structure and the transcription of a functional stk33 gene within the subclass Palaeognathae, but we could only find degenerate remnants of stk33 in all neognath birds analyzed. This led us to the conclusion that stk33 became a unitary pseudogene in the evolutionary history of the class Aves at the paleognath-neognath branch point during the late cretaceous period about 100 million years ago. We hypothesize that the pseudogenization of stk33 might have become fixed in neognaths due to either genetic redundancy or a non-orthologous gene displacement and present potential candidate genes for such an incident.

FTY720 (fingolimod) treatment tips the balance towards less immunogenic antigen-presenting cells in patients with multiple sclerosis.

OBJECTIVE: We aimed to clarify whether fingolimod has direct effects on antigen-presenting cells in multiple sclerosis patients. METHODS: Frequency and phenotype of directly ex vivo dendritic cells and monocytes were analyzed in 43 individuals, including fingolimod-treated and untreated multiple sclerosis patients as well as healthy subjects. These cells were further stimulated with lipopolysaccharide to determine functional effects of fingolimod treatment. RESULTS: Absolute numbers of CD1c+ dendritic cells and monocytes were not significantly reduced in fingolimod-treated patients indicating that fingolimod did not block the migration of antigen-presenting cells to peripheral blood. CD86 was upregulated on CD1c+ dendritic cells and thus their activation was not impaired under fingolimod treatment. Quantitative analyses of gene transcription in cells and protein content in supernatants from ex vivo CD1c+ dendritic cells and monocytes, however, showed lower secretion of TNFα, IL1-ß and IL-6 upon lipopolysaccharide-stimulation. These results could be matched with CD4+MOG-specific transgenic T cells exhibiting reduced levels of TNFα and IFN-γ but not IL-4 upon stimulation with murine dendritic cells loaded with MOG, when treated with fingolimod. CONCLUSIONS: Our data indicate that fingolimod - apart from trapping lymphocytes in lymph nodes - exerts its disease-modulating activity by rebalancing the immune tolerance networks by modulation of antigen-presenting cells.

Cladribine exerts an immunomodulatory effect on human and murine dendritic cells.

Cladribine is a purine nucleoside analog developed to treat lymphoid malignancies. Reported therapeutic benefits for the autoimmune disease multiple sclerosis indicate additional immunomodulatory effects beyond the well-characterized cytotoxic activity causing lymphopenia. Here, we demonstrate that cladribine reduces the secretion of inflammatory cytokines and chemokines by murine and human dendritic cells, the most potent antigen-presenting cells. This compound also modulates the expression of the activation markers CD86 and MHC II. Furthermore, cladribine affects the T cell priming capacity of dendritic cells, resulting in reduced induction of interferon-γ- and tumor necrosis factor-α-producing T cells and increased induction of interleukin-10-producing T cells. These effects, observed at cladribine concentrations in the therapeutically relevant range of serum steady-state concentrations for leukemia and multiple sclerosis, confirm the immunomodulatory activity of cladribine.