Semaphorin4A causes loss of mature oligodendrocytes and demyelination in vivo.

BACKGROUND: Inappropriate contact between the immune system and the central nervous system is thought to be a cause of demyelination. We previously reported the ability of the class IV semaphorin, Semaphorin4A (Sema4A), to induce apoptosis in human oligodendrocytes; however, these results have yet to be translated to an in vivo setting. Importantly, HIV-associated neurocognitive disorder remains a significant complication for patients on combined anti-retroviral therapy, with white matter damage seen on MRI. METHODS: Human cerebrospinal fluid and serum was assayed for Sema4A using a Sema4A-specific ELISA. Wild-type mice were injected with Sema4A via stereotaxic infusion. Data was assessed for significance using unpaired t tests, comparing the corpus callosum of PBS-injected mice versus Sema4A-injected mice. RESULTS: Here, we demonstrate elevated levels of Sema4A in the cerebrospinal fluid and serum of people with HIV infection. Furthermore, we demonstrate that direct injection of Sema4A into the corpus callosum of mice results in loss of myelin architecture and decreased myelin, concomitant with apoptosis of mature myelinating oligodendrocytes. Sema4A injection also causes increased activation of microglia. CONCLUSIONS: Taken together, our data further establish Sema4A as a potentially significant mediator of demyelinating diseases and a direct connection between the immune system and oligodendrocytes.

[Establishment of a chemiluminescent immunoassay(CLIA) and its application].

Objective To establish a chemiluminescent immunoassay(CLIA) for the detection of soluble CD100 (sCD100) and evaluate its preliminary clinical application for the detection of sCD100 in clinical cerebrospinal fluid samples. Methods Ascites were prepared using two hybridomas secreting monoclonal antibody (mAb) to CD100, and the antibodies were purified. Based on sandwich ELISA, the experiment conditions were optimized and the CLIA for detecting sCD100 was established. The sensitivity and stability of CLIA were evaluated. The level of sCD100 in cerebrospinal fluid samples of patients (n=18) was detected. Results CLIA exhibited high performance within a dynamic range 0.098-12.5 ng/mL, and the limit of detection (LOD) was 0.12 ng/mL. The intra-assay coefficient variations (CV) were between 3.8%-6.6% and inter-assay CV were 6.2%-14.1%. Using CLIA, we examined the level of sCD100 in cerebrospinal fluid of viral encephalitis patients. The results showed the level of sCD100 in the patients were higher than that in normal controls. Two cases of them were 9.4 and 13.8 times higher than the normal mean value of control group. Conclusion A rapid, sensitive and stable CLIA for detecting sCD100 has been successfully established, which can be used for the quantitative detection of trace sCD100 in cerebrospinal fluid samples.

Cerebrospinal fluid-derived Semaphorin3B orients neuroepithelial cell divisions in the apicobasal axis.

The spatial orientation of cell divisions is fundamental for tissue architecture and homeostasis. Here we analysed neuroepithelial progenitors in the developing mouse spinal cord to determine whether extracellular signals orient the mitotic spindle. We report that Semaphorin3B (Sema3B) released from the floor plate and the nascent choroid plexus in the cerebrospinal fluid (CSF) controls progenitor division orientation. Delivery of exogenous Sema3B to neural progenitors after neural tube opening in living embryos promotes planar orientation of their division. Preventing progenitor access to cues present in the CSF by genetically engineered canal obstruction affects the proportion of planar and oblique divisions. Sema3B knockout phenocopies the loss of progenitor access to the CSF. Sema3B binds to the apical surface of mitotic progenitors and exerts its effect via Neuropilin receptors, GSK3 activation and subsequent inhibition of the microtubule stabilizer CRMP2. Thus, extrinsic control mediated by the Semaphorin signalling orients progenitor divisions in neurogenic zones.

Validation of semaphorin 7A and ala-ß-his-dipeptidase as biomarkers associated with the conversion from clinically isolated syndrome to multiple sclerosis.

BACKGROUND: In a previous proteomics study using pooled cerebrospinal fluid (CSF) samples, we proposed apolipoprotein AI, apolipoprotein AIV, vitronectin, plasminogen, semaphorin 7A, and ala-ß-his-dipeptidase as candidate biomarkers associated with the conversion to clinically definite multiple sclerosis (CDMS) in patients with clinically isolated syndromes (CIS). Here, we aimed to validate these results in individual CSF samples using alternative techniques. METHODS: In a first replication study, levels of apolipoproteins AI and AIV, vitronectin, and plasminogen were measured by ELISA in CSF and serum of 56 CIS patients (29 patients who converted to CDMS (MS converters) and 27 patients who remained with CIS during follow-up (MS non-converters)) and 26 controls with other neurological disorders. Semaphorin 7A and ala-ß-his-dipeptidase levels were determined by selected reaction monitoring (SRM) in CSF of 36 patients (18 MS converters, 18 non-converters) and 20 controls. In a second replication study, apolipoprotein AI levels were measured by ELISA in CSF of 74 CIS patients (47 MS converters, 27 non-converters) and 50 individual controls, and levels of semaphorin 7A and ala-beta-his-dipeptidase were determined by SRM in 49 patients (24 MS converters, 25 non-converters) and 22 controls. RESULTS: CSF levels of apolipoprotein AI were increased (P = 0.043) and levels of semaphorin 7A and ala-ß-his-dipeptidase decreased (P = 4.4 × 10(-10) and P = 0.033 respectively) in MS converters compared to non-converters. No significant differences were found in serum levels for apolipoproteins AI and AIV, vitronectin, and plasminogen. Findings with semaphorin 7A and ala-ß-his-dipeptidase were also validated in the second replication study, and CSF levels for these two proteins were again decreased in MS converters versus non-converters (P = 1.2 × 10(-4) for semaphorin 7A; P = 3.7 × 10(-8) for ala-ß-his-dipeptidase). Conversely, apolipoprotein AI findings were not replicated and CSF levels for this protein did not significantly differ between groups. Furthermore, CSF semaphorin 7A levels were negatively associated with the number of T2 lesions at baseline and one-year follow-up. CONCLUSIONS: These results validate previous findings for semaphorin 7A and ala-ß-his-dipeptidase, and suggest that these proteins play a role as CSF biomarkers associated with the conversion to CDMS in CIS patients.