芦丁对丙烯酰胺致大鼠坐骨神经髓鞘损伤的保护作用

目的 通过观察芦丁(Rut)对丙烯酰胺(ACR)染毒大鼠坐骨神经髓鞘结构、髓鞘碱性蛋白(MBP)及髓鞘相关糖蛋白(MAG)表达的变化,探讨Rut对ACR致大鼠坐骨神经髓鞘损伤的保护作用.方法 成年SD雄性大鼠36只,随机分为4组:对照组(control,给予ddH2O)、20 mg/kg ACR染毒组(ACR)、100...     

Quantitative trait loci disposing for both experimental arthritis and encephalomyelitis in the DA rat; impact on severity of myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis and antibody isotype pattern

Quantitative trait loci (QTL) controlling inflammatory diseases with different organ specificity may hypothetically either be unique for one disease or shared among different diseases. We have investigated whether five non-MHC QTL controlling susceptibility to experimental arthritis in the DA rat also influence myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE) in an F2 intercross between inbred DA and PVG.RT1^a rats. Two of the five chromosome regions affecting arthritis in the DA rat also regulate phenotypes of EAE. The DA allele at markers in Cia3(collagen-induced arthritis QTL) on chromosome 4 is associated with more severe EAE and high levels of anti-MOG antibodies of the IgG2c subclass. Since production of antibodies of the IgG2c subclass may be stimulated by Th1 cells, and there is previous evidence that such cells promote EAE, it is possible that both of the studied phenotypes are controlled by the same gene or genes regulating Th1/Th2 cell differentiation. Furthermore, we show that Oia2(oil-induced arthritis QTL) on chromosome 4 regulates levels of anti-MOG antibodies of the IgG1 subclass and of anti-MOG IgE, but that this gene region does not affect clinical disease severity in our study. Since production of IgE and IgG1 may be stimulated by Th2 cells, this QTL may also control Th1/Th2 bias. We conclude that Cia3and Oia2regulate MOG-induced EAE in rats. Furthermore, since both EAE and arthritis phenotypes co-localize to these gene regions, they may harbor genes which are key regulators of pathogenic immune responses.     

The presence of functional mannose receptor on macrophages at the maternal-fetal interface

BACKGROUND: The mannose receptor (MR) is involved in the initiation of the immune response and regulation of homeostasis during inflammation and tissue remodeling. METHODS: Distribution, endocytosis and possible natural ligand tumor associated glycoprotein-72 (TAG-72) for the MR have been examined by immunohistology, immunocytochemistry and flow cytometry at the maternal-fetal interface, characterized by extensive tissue remodeling. RESULTS: Contrary to disseminated distribution of the MR positive (MR+) cells in term placenta, the MR+ cells of early pregnancy decidua intimately surrounded glands and followed tissue distribution of CD14 positive cells. The mannose receptor was present on freshly isolated first trimester decidual mononuclear cells and distributed mostly on macrophages (77.08 +/- 10.55%, mean +/- SD). The expression of the MR on CD14 positive cells decreased following 18 h culture (P < 0.01) and was accompanied by the reduction of fluorescein isothiocyanate (FITC)-dextran uptake. PAM-1 anti-MR antibody, mannan and TAG-72 reduced FITC-dextran uptake by decidual macrophages. CONCLUSIONS: These data indicate that the MR+ macrophages, surrounding early decidual glands, are able to internalize ligands for carbohydrate recognition domain of the receptor, including decidual secretory phase mucin TAG-72.     

Human placentae membrane receptor for IgG—i. Studies on properties and solubilization of the receptor

Characterization of the human placental membrane receptor for human ¹²⁵I-IgG is described. The receptor bound specifically both monomers and aggregates of human IgG. Human colostral IgA, bovine, sheep, pig, and horse IgG were not bound. No effect of pH in the range 6.6–7.4, ionic strength in the range 0.1–0.5, and temperature between 4 and 45°C on the binding was found. A water-soluble fraction containing the active receptor (glycoprotein fraction-PGP) was obtained from the placental membranes using lithium diiodosalicylate. The solubilized receptor interacted with IgG better at 4°C than at 20°C or 37°C. The results on replacement of monomeric IgG by aggregated IgG, and vice versa, suggest that both monomers and aggregates of human IgG, were bound to the same receptor sites. The apparent association constant for monomeric human IgG was 0.86 ± 0.2 × 10⁷ mole^?1, and 2.0 ± 0.16 × 10¹⁵ IgG molecules were bound per l mg of the membrane protein. Formaldehyde (0.1%), 2-mercaptoethanol (50 mM), and periodate (4 mM) showed no effect on the binding properties of the membrane-bound and on the solubilized receptor, as well. Higher concentrations of periodate (10 mM or 20 mM) decreased the binding of IgG to membranes but showed no effect on the water-soluble receptor. Both the membrane-bound and the solubilized receptor were sensitive to papain. Pronose abolished the receptor activity after prolonged proteolysis only. Neuraminidase did not affect the activity of the receptor. The decrease of the binding activity of the membrane-bound receptor by trypsin and phospholipase C was due to a release of a material containing an active receptor. No effect of trypsin or phospholipase C on the activity of solubilized receptor was observed. The results obtained suggest a protein character of the placental Fc receptor. After electrophoresis of ¹²⁵I-labeled solubilized receptor in polyacrylamide gel in the presence of SDS, 2 major protein peaks with molecular weights of 74,000 and 104,000 and 3 minor peaks with molecular weights of 56,000, 144,000, and 163,000 were found.     

Clonal expansion of myelin basic protein-reactive T cells in patients with multiple sclerosis: Restricted T cell receptor V gene rearrangements and CDR3 sequence

Myelin basic protein (MBP)-reactive T cells are thought to play an important role in the pathogenesis of multiple sclerosis (MS). In some patients with MS, these autoreactive T cells display a limited heterogeneity in their epitope recognition and T cell receptor (TCR) variable (V) gene usage. These individual-dependent properties of MBP-reactive T cells have led to the speculation that they may represent clonal expansion in vivo in some MS patients. In the present study, 51 MBP-reactive T cell clones derived from patients with MS and healthy individuals were examined for their epitope recognition and the TCR Vα and Vβ gene rearrangements. The V gene junctional region sequences of identified α and β genes were further analyzed to probe their clonal origins, as the sequences are unique for individual clones. Our data showed that 26 clones derived from nine patients with MS shared a predominant reactivity to the immunodominant regions of MBP, 84–102, 110–129 and 143–168, and used various TCR Vα and Vβ rearrangements. The V gene usage of the clones was restricted to certain Vα Vβ combination(s) in a given MS patient, but varied among different patients. The sequence analysis revealed that the clones generated from a given patient shared a limited or a single junctional region sequence pattern(s), indicating their oligoclonal or monoclonal origin(s). In contrast, 25 MBP-reactive T cell clones derived from normal individuals exhibited unfocused epitope recognition and V gene usage. Thus, the limited heterogeneity of MBP-reactive T cells in their structural and functional charactertistics reflects their clonal expansion in vivo in some patients with MS.     

Aberrant signaling in the TNFalpha/TNF receptor 1 pathway of the NZM2410 lupus-prone mouse

The purpose of this study was to evaluate the ability to induce TNFalpha-dependent apoptosis in vivo in predisease lupus-prone NZM2410 and derived B6.NZM congenic mouse strains. An endotoxicosis model that utilizes LPS and d-galactosamine to induce mortality by TNFalpha/TNFR1-dependent hepatocyte apoptosis was used to assess TNFalpha production, apoptotic signaling, and effects on the production of IL-6 and IL-10. NZM2410 was found to be resistant to endotoxicosis and to produce significantly less TNFalpha-induced IL-6 and IL-10. At low doses of LPS, partial resistance was associated with the Tnfa(w) allele. At higher doses of LPS, partial resistance cosegregated with lupus-susceptibility loci and functionally mapped downstream of caspase 3. Additional partial resistance in NZM2410 was also found upstream of FADD. These results demonstrate the existence of multiple defects in the TNFalpha/TNFR1 signaling pathway in the NZM2410 mouse and their relevance to lupus pathogenesis is discussed.     

TNF receptor-associated factor-1 (TRAF1) negatively regulates Toll/IL-1 receptor domain-containing adaptor inducing IFN-beta (TRIF)-mediated signaling

Toll-like receptor 3 (TLR3) plays an important role in antiviral responses through recognizing viral double-stranded RNA produced during viral infection and mediating induction of type I IFN. TRIF is a Toll/IL-1 receptor (TIR) domain-containing adaptor protein that is associated with TLR3 and critically involved in TLR3-mediated signaling. In yeast two-hybrid screens, we identified TNF receptor-associated factor (TRAF)1 as a TRIF-interacting protein. The TRAF-C domain of TRAF1 and the TIR domain of TRIF were responsible for their interaction. Overexpression of TRAF1 inhibited TRIF- and TLR3-mediated activation of NF-kappaB, IFN-stimulated response element and the IFN-beta promoter. Overexpression of TRIF caused caspase-dependent cleavage of TRAF1. The cleaved N-terminal but not C-terminal fragment of TRAF1 was responsible for inhibiting TRIF signaling. Mutation of the caspase cleavage site of TRAF1 or addition of the caspase inhibitor crmA inhibited TRAF1 cleavage and abolished the ability of TRAF1 to inhibit TRIF signaling, suggesting that TRIF-induced cleavage of TRAF1 is required for its inhibition of TRIF signaling. Our findings provide a novel mechanism for negative regulation of TRIF-mediated signaling.     

Biallelic expression of Tbx1 protects the embryo from developmental defects caused by increased receptor tyrosine kinase signaling

Results : The loss of function of two Sprouty genes, which encode feedback antagonists of receptor tyrosine kinase (RTK) signaling, phenocopy many defects associated with 22q11DS in the mouse. The stepwise reduction of Sprouty gene dosage resulted in different phenotypes emerging at specific steps, suggesting that the threshold up to which a given developmental process can tolerate increased RTK signaling is different. Tbx1 heterozygosity significantly exacerbated the severity of all these defects, which correlated with a substantial increase in RTK signaling. 相似文献   

The effect of ganglioside GQ1b on the NMDA receptor signaling pathway in H19-7 cells and rat hippocampus

Gangliosides, sialic acid-containing glycosphingolipids, are related to various synaptic functions in the rat brain. Previously, we investigated the behavioral effects of the ganglioside GQ1b on learning and memory using the Y-maze and Morris water maze test. GQ1b-treated rats showed highly increased memory performance on the Y-maze and the Morris water maze test. In this study, we determined the role of GQ1b on the activation of the N-methyl-d-aspartate (NMDA) receptor signaling pathway in H19-7 rat hippocampal cells and the hippocampus of rats. After 12 h of treatment with GQ1b, the expression levels of NMDA receptor subunit 2A and 2B were increased in H19-7 cells and the hippocampus of rats. In addition, treatment of GQ1b increased the tyrosine phosphorylation of NR2B that may enhance NMDA receptor synaptic activation and enhancement of NMDA receptors. Also, following GQ1b treatment, the phosphorylation of extracellular signal-regulated kinases (ERK1/2) and protein kinase A, a cAMP activated protein kinase (PKA) increased in H19-7 cells and the hippocampus of rats. These increases resulted in an increase in the phosphorylation of cAMP response element binding protein (CREB). These results suggest that GQ1b might facilitate the activation of the NMDA receptor signaling pathway in the hippocampus of rats, an effect which is dependent on ERK1/2, PKA and CREB phosphorylation. Also, these data support our previous result that GQ1b improves the learning and memory of rats.     

Desensitization of chemokine receptor CCR5 in dendritic cells at the early stage of differentiation by activation of formyl peptide receptors

Chemokine receptors are subjected to heterologous desensitization by activation of formyl peptide receptors. We investigated the cross-talk between formyl peptide receptors and the chemokine receptor CCR5 in human monocyte-differentiated immature dendritic cells (iDC). Monocytes cultured with GM-CSF and IL-4 for 4 days exhibit markers characteristic of iDC and maintain the expression of both formyl peptide receptors FPR and FPRL1, as well as CCR5. Pretreatment of iDC with W peptide (WKYMVm), a potent agonist for FPR and FPRL1 but with preference for FPRL1, resulted in down-regulation of CCR5 from the cell surface and reduced cell response to the CCR5 ligands through a PKC-dependent pathway. Furthermore, W peptide induced a PKC-dependent phosphorylation of CCR5 and inhibited infection of iDC by R5 HIV-1. Our results indicate that the expression and functions of CCR5 in iDC can be attenuated by W peptide, which activates formyl peptide receptors, and suggest an approach to the design of novel anti-HIV-1 agents.     

Differential signaling of cmvIL‐10 through common variants of the IL‐10 receptor 1

Human IL‐10 (hIL‐10) signaling is mediated by receptors consisting of two subunits, IL‐10 receptor 1 (IL‐10R1) and IL‐10 receptor 2. Two common variants of the IL‐10R1 (Ser 138 Gly (single‐nucleotide polymorphism 3, SNP3) and Gly 330 Arg (SNP4)) are associated with diverse disease phenotypes. Viral homologs to hIL‐10, such as cmvIL‐10, utilize the same IL‐10 receptor complex as part of viral immune evasion strategies. For the present study we hypothesized that IL‐10R1 variants alter the ability of viral IL‐10 to utilize the IL‐10R1 signaling pathway. HeLa cell clones expressing different IL‐10R1 haplotypes (WT or any variant) were incubated with hIL‐10 or cmvIL‐10. In cells expressing IL‐10R1‐WT, cmvIL‐10 (both non‐glycosylated‐ and HeLa‐expressed) resulted in equal or slightly stronger STAT3 phosphorylation compared with hIL‐10. In clones expressing IL‐10R1‐SNP3, IL‐10R1‐SNP4 or IL‐10R1‐SNP3+4, the cmvIL‐10 showed significantly less STAT3 phosphorylation, especially when HeLa‐expressed cytokines were used. Time course experiments demonstrated a slower kinetic of cmvIL‐10 STAT3 activation through the variant IL‐10R1. Similarly, IL‐10R1 variants decreased the cmvIL‐10‐induced SOCS3 and signaling lymphocytic activation molecule mRNA expression. These data suggest that the IL‐10R1 variants differentially reduce the signaling activity of cmvIL‐10 and thereby may affect CMV's ability to escape from the host's immune surveillance.     

Opposite alterations of NPFF1 and NPFF2 neuropeptide FF receptor density in the triple MOR/DOR/KOR-opioid receptor knockout mouse brains

Mice lacking the mu-delta-kappa-opioid receptor (MOR/DOR/KOR) genes and their corresponding wild-type littermates have been used to quantify NPFF(1) and NPFF(2) (neuropeptide FF) receptors by in vitro autoradiography in the central nervous tissues. Adjacent coronal sections were labelled with [125I]YVP ([125I]YVPNLPQRF-NH(2)) and [125I]EYF ([125I]EYWSLAAPQRF-NH(2)) as specific radioligands for NPFF(1) and NPFF(2) receptors, respectively. NPFF(2) receptors are predominantly expressed in both genotypes, but their density increases significantly in non cortical regions of mutant mice: 64% in the amygdaloid area, 89, 308, 1214 and 49% in the nucleus of the vertical limb of the diagonal band, substantia nigra, the vestibular nucleus and the spinal cord, respectively. In contrast, the density of the NPFF(1) subtype is lower than NPFF(2) in both genotypes and significantly decreased in some brain areas of mutant mice: -99, -90 and -90% in the nucleus of the vertical limb of the diagonal band, substantia nigra and the spinal cord, respectively. This study shows that mice lacking opioid receptors have brain region-dependent increases (NPFF(2)) and decreases (NPFF(1)) in NPFF receptors densities and suggests a different functional participation of each NPFF receptor subtype in the actions of opioids.     

Sphingosine-1-phosphate acting via the S1P1 receptor is a downstream signaling pathway in ceramide-induced hyperalgesia

Ceramide is a potent pro-inflammatory sphingolipid recently shown to exert potent hyperalgesic responses in rats. Once generated, ceramide is converted by sphingosine kinase (SphK) 1 and/or 2 to one of its active metabolite sphingosine-1-phosphate (S1P), which in turn signals through G-protein coupled S1P receptors. The objectives of this paper were to define whether ceramide-induced hyperalgesia is driven by S1P. Our results show that intraplantar injection of ceramide in rats led to a time-dependent development of thermal hyperalgesia that was associated with an increase in tumor necrosis factor-α (TNF-α) in paw tissues. The development of hyperalgesia was significantly attenuated by a soluble TNF receptor I. TNF-α is known to activate SphK1, thus S1P production, and our results demonstrate that, the development of hyperalgesia was attenuated in a dose-dependent fashion by a well characterized inhibitor of SphK1 and SphK2 (SK-I) and by a murine monoclonal anti-S1P antibody (LT1002). LT1017, the isotype-matched control monoclonal antibody for LT1002, had no effect. Our results further demonstrate that S1P contributes to the development of hyperalgesia via the S1P receptor 1 subtype (S1PR₁), since responses were blocked by a well characterized S1PR₁ antagonist, W146, but not by its inactive enantiomer, W140. Collectively, these results provide mechanistic evidence implicating the S1P-to-S1PR₁ pathway as a downstream signaling pathway in ceramide-induced hyperalgesia. Targeting S1P may be a novel therapeutic approach in pain management.     

Characterization of the human chemerin receptor--ChemR23/CMKLR1--as co-receptor for human and simian immunodeficiency virus infection, and identification of virus-binding receptor domains

Studies were conducted to elucidate co-receptor spectrum and function of the inflammatory receptor, CMKLR1/ChemR23, which was recently identified as the receptor for the cystatin-like chemoattractant, TIG2, also named chemerin. An infection model was applied based on stably transfected NP-2.CD4 host cells expressing various co-receptor constructs and exposed to panels of HIV-1, HIV-2 and SIV primary isolates. In a panel of 27 HIV-1 isolates tested, 12 isolates could use CMKLR1/ChemR23. As expected from a relatively high sequence homology with the extracellular domains of CCR3, HIV-1 isolates showing R3 tropism were particularly efficient in using CMKLR1/ChemR23. In addition, 5 out of 7 HIV-2 isolates and 13 out of 15 SIV (SMM-3 origin) used CMKLR1/ChemR23, in accordance with the previously documented ability of these isolates to use several co-receptors. In order to define important extracellular epitopes for the viral interaction, a hybrid receptor model was applied. This was based on the fact that the rat receptor, although structurally very similar to the human orthologue, was inefficient as viral co-receptor. When the rat receptor was "humanized" to include regions unique to the human receptor (N-terminus or second extracellular loop), exposure to HIV-1, HIV-2 and SIV isolates resulted in infection. The relative importance of the two critical receptor regions differed between HIV-1/HIV-2 on the one hand and SIV on the other. The results strongly support that the chemerin receptor, in the presence of CD4, functions as a "minor co-receptor" promoting infection by these classes of viruses.     

The involvement of the Toll-like receptor signaling and Nrf2-Keap1 pathways in the in vitro regulation of IL-8 and HMOX1 for skin sensitization

In vitro gene profiling studies have associated the molecular pathways of Nrf2-Keap1 and Toll-like receptor (TLR) signaling with skin sensitization. In this study, the role of these pathways in the regulation of protein biomarkers for skin sensitization was further elucidated using transient gene knock-down of key components of the signaling cascades in HaCaT cells after exposure to dinitrochlorobenzene (DNCB). The effect of targeting these pathways was established through evaluation of heme oxygenase1 (HMOX1) and interleukin (IL)-8 production. These experiments showed that Nrf2 is not involved in regulating HMOX1 after exposure to DNCB, but that activation of TLR signaling moderates the expression of HMOX1. The regulation of IL-8 depended on Nrf2, but also on the Toll/interleukin-1 receptor (TIR)-domain-containing adapter-inducing interferon-β (TRIF) adaptor protein in TLR signaling. This study provides new insights into the regulation of HMOX1 and IL-8, but the exact regulating mechanisms remain to be further elucidated.     

Structural requirements for the interaction of human IgM and IgA with the human Fcα/μ receptor

Here we unravel the structural features of human IgM and IgA that govern their interaction with the human Fcα/μ receptor (hFcα/μR). Ligand polymerization status was crucial for the interaction, because hFcα/μR binding did not occur with monomeric Ab of either class. hFcα/μR bound IgM with an affinity in the nanomolar range, whereas the affinity for dimeric IgA (dIgA) was tenfold lower. Panels of mutant IgM and dIgA were used to identify regions critical for hFcα/μR binding. IgM binding required contributions from both Cμ3 and Cμ4 Fc domains, whereas for dIgA, an exposed loop in the Cα3 domain was crucial. This loop, comprising residues Pro440–Phe443, lies at the Fc domain interface and has been implicated in the binding of host receptors FcαRI and polymeric Ig receptor (pIgR), as well as IgA‐binding proteins produced by certain pathogenic bacteria. Substitutions within the Pro440–Phe443 loop resulted in loss of hFcα/μR binding. Furthermore, secretory component (SC, the extracellular portion of pIgR) and bacterial IgA‐binding proteins were shown to inhibit the dIgA–hFcα/μR interaction. Therefore, we have identified a motif in the IgA–Fc inter‐domain region critical for hFcα/μR interaction, and highlighted the multi‐functional nature of a key site for protein–protein interaction at the IgA Fc domain interface.