Overexpression of PD-L1 causes germ cells to slough from mouse seminiferous tubules via the PD-L1/PD-L1 interaction.

Spermatogenesis is a cyclical process in which different generations of spermatids undergo a series of developmental steps at a fixed time and finally produce spermatids. Here, we report that overexpression of PD-L1 (B7 homolog1) in the testis causes sperm developmental disorders and infertility in male mice, with severe malformation and sloughing during spermatid development, characterized by disorganized and collapsed seminiferous epithelium structure. PD-L1 needs to be simultaneously expressed on Sertoli cells and spermatogonia to cause spermatogenesis failure. After that, we excluded the influence of factors such as the PD-L1 receptor and humoral regulation, confirming that PD-L1 has an intrinsic function to interact with PD-L1. Studies have shown that PD-L1 not only serves as a ligand but also plays a receptor-like role in signal transduction. PD-L1 interacts with PD-L1 to affect the adhesive function of germ cells, causing malformation and spermatid sloughing. Taken together, these results indicate that PD-L1 can interact with PD-L1 to cause germ cell detachment and male infertility.

Programmed Death-1 Deficiency Aggravates Motor Dysfunction in MPTP Model of Parkinson's Disease by Inducing Microglial Activation and Neuroinflammation in Mice.

Abundant reactive gliosis and neuroinflammation are typical pathogenetic hallmarks of brains in Parkinson's disease (PD) patients, but regulation mechanisms are poorly understood. We are interested in role of programmed death-1 (PD-1) in glial reaction, neuroinflammation and neuronal injury in PD pathogenesis. Using PD mouse model and PD-1 knockout (KO) mice, we designed wild-type-control (WT-CON), WT-1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (WT-MPTP), PD-1-KO-control (KO-CON) and PD-1-KO-MPTP (KO-MPTP), and observed motor dysfunction of animal, morphological distribution of PD-1-positive cells, dopaminergic neuronal injury, glial activation and generation of inflammatory cytokines in midbrains by motor behavior detection, immunohistochemistry and western blot. WT-MPTP mouse model exhibited decrease of PD-1/Iba1-positive microglial cells in the substantia nigra compared with WT-CON mice. By comparison of four groups, PD-1 deficiency showed exacerbation in motor dysfunction of animals, decreased expression of TH protein and TH-positive neuronal protrusions. PD-1 deficiency enhanced microglial activation, production of proinflammatory cytokines like inducible nitric oxide synthase, tumor necrosis factor-α, interleukin-1ß and interleukin-6, and expression and phosphorylation of AKT and ERK1/2 in the substantia nigra of MPTP model. We concluded that PD-1 deficiency could aggravate motor dysfunction of MPTP mouse model by inducing microglial activation and neuroinflammation in midbrains, suggesting that PD-1 signaling abnormality might be possibly involved in PD pathogenesis.

Reactive Astrocytes Display Pro-inflammatory Adaptability with Modulation of Notch-PI3K-AKT Signaling Pathway Under Inflammatory Stimulation.

Astrocytes are major glial cells critical in assisting the function of the central nervous system (CNS), but the functional changes and regulation mechanism of reactive astrocytes are still poorly understood in CNS diseases. In this study, mouse primary astrocytes were cultured, and inflammatory insult was performed to observe functional changes in astrocytes and the involvement of Notch-PI3K-AKT signaling activation through immunofluorescence, PCR, Western blot, CCK-8, and inhibition experiments. Notch downstream signal Hes-1 was clearly observed in the astrocytes, and Notch signal inhibitor GSI dose-dependently decreased the cleaved Notch-l level without an influence on cell viability. Inflammatory insult of lipopolysaccharide plus interferon-γ (LPS+IFNγ) induced an increase in pro-inflammatory cytokines, that is, iNOS, IL-1ß, IL-6, and TNF, at the protein and mRNA levels in activated astrocytes, which was reduced or blocked by GSI treatment. The cell viability of the astrocytes did not show significant differences among different groups. While an increase in MyD88, NF-кB, and phosphor-NF-кB was confirmed, upregulation of PI3K, AKT, and phosphor-AKT was observed in the activated astrocytes with LPS+IFNγ insult and was reduced by GSI treatment. Inhibitor experiments showed that inhibition of Notch-PI3K-AKT signaling activation reduced the pro-inflammatory cytokine production triggered by LPS+IFNγ inflammatory insult. This study showed that the reactive astrocytes displayed pro-inflammatory adaptability through Notch-PI3K-AKT signaling activation in response to inflammatory stimulation, suggesting that the Notch-PI3K-AKT pathway in reactive astrocytes may serve as a promising target against CNS inflammatory disorders.

Neurokinin-3 peptide instead of neurokinin-1 synergistically exacerbates kainic acid-inducing degeneration of neurons in the substantia nigra of mice.

Neurokinin peptides neurokinin-1 (NK1), neurokinin-3 (NK3), and related receptors are abundantly distributed in the substantia nigra (SN) and evidenced by their possible roles in the Parkinson's disease. Differential intervention roles of NK3 on kainic acid (KA)-induced neuronal injury in the SN of mice were thus in vitro and in vivo studied by Fluoro-Jade C (FJC) staining, immunohistochemistry to tyrosine hydroxylase (TH) or phospho-NMDA receptor, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. It revealed that (i) in contrast to protective effect of NK1 agonist septide that reduced FJC-positive degenerative neurons and lesion volume insulted by KA, NK3 agonist senktide significantly increased FJC-positive ones and lesion volume, and this effect was sufficiently reversed by NK3 antagonist SB218795; (ii) similarly, senktide reduced TH-positive neurons and this effect was antagonized by SB218795, but septide increased TH-positive ones; (iii) mechanistic observation showed differential influences of NK1 and NK3 agonists on phosphorylated-NMDA receptor subunit 1 (phospho-NMDAR1) and glial fibrillary acidic protein-expressing astrocytes, i.e. senktide enhanced of NMDA receptor phosphorylation and astrocyte activity, while septide reduced NMDA receptor phosphorylation and astrocytic response; (iv) cell culture further confirmed the exacerbating effect of NK3 agonist on KA-induced lesion of nigral cells or dopaminergic neurons, in which administration of senktide alone did not show significant cell toxicity. This study presents new evidence that neurokinin NK3 instead of NK1 synergistically exacerbate excitotoxic neuronal degeneration in the SN in a dose-dependent manner and possibly through modulation of NMDA receptor phosphorylation and astrocyte activity, suggesting their potential significance in novel pharmaceutical therapy against Parkinson's disease.

Identification and kainic acid-induced up-regulation of low-affinity p75 neurotrophin receptor (p75NTR) in the nigral dopamine neurons of adult rats.

Parkinson's disease is a common and severe debilitating neurological disease that results from massive and progressive degenerative death of dopamine neurons in the substantia nigra, but the mechanisms of neuronal degeneration and disease progression remains largely obscure. We are interested in possible implications of low-affinity p75 neurotrophin receptor (p75NTR), which may mediate neuronal apoptosis in the central nervous system, in triggering cell death of the nigral dopamine neurons. The RT-PCR and immunohistochemistry were carried out to detect if p75NTR is expressed in these nigral neurons and up-regulated by kainic acid (KA) insult in adult rats. It revealed p75NTR-positive immunoreactivity in the substantia nigra, and co-localization of p75NTR and tyrosine hydroxylase (TH) was found in a large number of substantia nigra neurons beside confirmation of p75NTR in the choline acetyltransferase (ChAT)-positive forebrain neurons. Cell count data further indicated that about 47-100% of TH-positive nigral neurons and 98-100% of ChAT-positive forebrain neurons express p75NTR. More interestingly, significant increasing in both p75NTR mRNA and p75NTR-positive neurons occurred rapidly following KA insult in the substantia nigra of animal model. The present study has provided first evidence on p75NTR expression and KA-inducing p75NTR up-regulation in substantia nigra neurons in rodent animals. Taken together with previous data on p75NTR functions in neuronal apoptosis, this study also suggests that p75NTR may play important roles in neuronal cell survival or excitotoxic degeneration of dopamine neurons in the substantia nigra in pathogenesis of Parkinson's disease in human beings.

Fluoro-Jade C can specifically stain the degenerative neurons in the substantia nigra of the 1-methyl-4-phenyl-1,2,3,6-tetrahydro pyridine-treated C57BL/6 mice.

Fluoro-Jade C, a new-developed fluorescent dye, has been successfully applied for identification of neuronal degeneration in the substantia nigra of 1-methyl-4-phenyl-1,2,3,6-tetrahydro pyridine (MPTP)-treated mice in the present study. The animal model was first prepared by intraperitoneal injection of neurotoxicant MPTP that can specifically induce degeneration of dopamine neurons in the substantia nigra of C57BL/6 mice. Fluoro-Jade C was then utilized to stain the midbrain sections and semiquantitation analysis was carried out in comparison with controls. It revealed that Fluoro-Jade C-positive cells showed strong green color in neuronal profile and were observed in the substantia nigra of MPTP-treated mice whereas they were not detected in that of controls. The Fluoro-Jade C-positive cells were mostly shrunken or smaller-sized in their cell bodies in comparing with that of normal dopamine neurons of controls. In the midbrain of MPTP-treated mice, Fluoro-Jade C-positive neuronal cells were exclusively distributed in the substantia nigra pars compacta, but rarely seen in the ventral tegemental area where dopamine neurons were numerously distributed. Double-labeling experiments indicated that a population of Fluoro-Jade C-positive cells (23%) exhibited neuron-specific nuclear protein-immunoreactivity and none of them showed immunoreactivity to glial cell marker glial fibrillary acid protein. However, most of Fluoro-Jade C-positive degenerative neurons (98%) lost their immunoreactivity to dopaminergic marker tyrosine hydroxylase in the substantia nigra of MPTP-treated mice. Taken together with previous observations, this study has presented that Fluoro-Jade C can be sensitively and specifically utilized to identify the neuronal degeneration in the substantia nigra of rodent animals receiving MPTP insult.

Loss of microRNA-124 expression in neurons in the peri-lesion area in mice with spinal cord injury.

MicroRNA-124 (miR-124) is abundantly expressed in neurons in the mammalian central nervous system, and plays critical roles in the regulation of gene expression during embryonic neurogenesis and postnatal neural differentiation. However, the expression profile of miR-124 after spinal cord injury and the underlying regulatory mechanisms are not well understood. In the present study, we examined the expression of miR-124 in mouse brain and spinal cord after spinal cord injury using in situ hybridization. Furthermore, the expression of miR-124 was examined with quantitative RT-PCR at 1, 3 and 7 days after spinal cord injury. The miR-124 expression in neurons at the site of injury was evaluated by in situ hybridization combined with NeuN immunohistochemical staining. The miR-124 was mainly expressed in neurons throughout the brain and spinal cord. The expression of miR-124 in neurons significantly decreased within 7 days after spinal cord injury. Some of the neurons in the peri-lesion area were NeuN(+)/miR-124(-). Moreover, the neurons distal to the peri-lesion site were NeuN(+)/miR-124(+). These findings indicate that miR-124 expression in neurons is reduced after spinal cord injury, and may reflect the severity of spinal cord injury.

[Identification of six kinds of monoclonal antibodies against rat Nogo-A molecule in the immunofluorescent histochemical staining].

AIM: To detect and characterize of 6 monoclonal antibodies (mAbs) against different epitopes of rat Nogo-A molecule in immunohistochemistry to decide their applications in futrue. Four mAbs against Nogo66 fragment are named Nogo66-1, Nogo66-2, Nogo66-3 and Nogo66-4. The rest of 2 mAbs against N-termial 570-691aa fragment are named NogoN-1 and NogoN-2. METHODS: The immunofluorescence staining was used to detect the reactivity and specificity of those 6 mAbs in spinal tissue sections of rat. RESULTS: All 6 mAbs were double-labelled with commercial rabbit anti-Rat Nogo-A polyclonal antibody (PcAb) in spinal cord sections respecitvely. All 6 mAbs were colocalization with MBP respectively. However Nogo66-3 and NogoN-1 could also be double-staining with GFAP respectively. CONCLUSION: Nogo66-1, Nogo66-2, Nogo66-4 and NogoN-2 could recognize specifically in Nogo-A protein of tissues in immunohistochemical methods.

[Recovery of movement after spinal cord injury in DO11.10 transgenic mouse].

AIM: To analysis the role of T lymphocytes in spinal cord regeneration by comparing the recovery of movement and the morphological changes of injury area between BALB/c and DO11.10 transgenic mice. METHODS: Producing a crush injury model of spinal cord with special forceps. Analyze the changes of spinal cord injury area with H&E and GFAP, CD11b and lymphocytic immunohistochemical staining. Evaluate the recovery of movement function with Basso-Beattie-Bresnahan (BBB) locomotion testing system at 0, 7, 14 and 21 day post-injury (dpi). RESULTS: There were thicker and fastened glial scar at 21 dpi in the BALB/c mice but not in DO11.10 mice. The number of macrophages/microglia infiltrated in spinal cord injury area were more in DO11.10 than that in BALB/c mice at 14 dpi. The numbers of T lymphocytes infiltrated in spinal cord injury area were less in DO11.10 than that in BALB/c mice at 21 dpi. In addition, compare to BALB/c mice, the locomotion movement recovery of DO11.10 mice were much more significant within 3 weeks after spinal cord injury by BBB scoring system. CONCLUSION: The infiltrated autoimmune activation T lymphocytes which specifically react to neural antigens are not beneficial to recovery of movement after spinal cord injury in mice.

Nigrostriatal neurons in rat express the glial cell line-derived neurotrophic factor receptor subunit c-RET.

The substantia nigra neurons expressing c-RET, a glial cell line-derived neurotrophic factor (GDNF) receptor intracellular tyrosine kinase subunit, were investigated in rats by using a double labeling method which combined retrograde horseradish peroxidase (HRP) labeling after injection into the striatum with immunohistochemistry to c-RET. It was revealed that the distribution of c-RET-immunoreactive neurons and HRP-labeled nigrostriatal neurons overlapped. Numerous double-labeled HRP/c-RET neurons were found in the substantia nigra pars compacta with predominate distribution ipsilateral to the injected striatum. Semiquantitative cell count indicated that a large percentage (97%) of HRP-labeled neurons showed c-RET immunoreactivity. Furthermore, double-labeled HRP/c-RET ones constituted only 61% of total c-RET-immunoreactive neurons in the substantia nigra ipsolateral to the injected striatum. Taken together with previous observations on glial cell line-derived neurotrophic factor in the basal ganglia, this study provides evidence that the c-RET protein may mediate biological activity of GDNF family ligands in most of projecting neurons in the substantia nigra pars compacta where the dopaminergic neurons are numerously distributed. Specially, it suggests that c-RET-mediating signaling cascades may play important roles in neuron-glial interaction that support and sustain nigrostriatal neuronal circuits in the basal ganglia.