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1.
Peptidoglycan (PGN) is the major cell wall component (90%, w/w) of Gram-positive bacteria and consists of N-acetylglucosamine (GlcNAc) and N-acetylmuramic acid (MurNAc) disaccharide repeating arrays that are cross-linked by short peptides. We hypothesized that PGN is a ligand for pathogen-associated pattern-recognition proteins. Mannose-binding lectin (MBL) and serum amyloid component P are two carbohydrate-binding innate immune proteins present in the blood. In this study we show that human MBL, but not serum amyloid component P, binds significantly to PGN via its C-type lectin domains, and that the interaction can be more effectively competed by GlcNAc than by MurNAc. Surface plasmon resonance analyses show that native MBL binds immobilized PGN with high avidity. Competition experiments also show that both native MBL and MBL(n/CRD), a 48-kDa recombinant trimeric fragment of MBL containing neck and carbohydrate recognition domains, have higher affinity for GlcNAc than for MurNAc. Protein arrays and ELISA show that PGN increases the secretion of TNF-alpha, IL-8, IL-10, MCP-2, and RANTES from PMA-stimulated human monocytic U937 cells. Interestingly, the presence of MBL together with PGN increases the production of IL-8 and RANTES, but reduces that of TNF-alpha. Our results indicate that Gram-positive bacterial is a biologically relevant ligand for MBL, and that the collectin preferentially binds to the GlcNAc moiety of the PGN via its C-type lectin domains. MBL inhibits PGN-induced production of proinflammatory cytokines while enhancing the production of chemokines by macrophages, which suggests that MBL may down-regulate macrophage-mediated inflammation while enhancing phagocyte recruitment.  相似文献   

2.
Peptidoglycan recognition proteins (PGRPs) are involved in the recognition of pathogen-associated molecular patterns. The well known pathogen-associated molecular patterns include LPS from Gram-negative bacteria and lipoteichoic acid (LTA) from Gram-positive bacteria. In this work, the crystal structures of two complexes of the short form of camel PGRP (CPGRP-S) with LPS and LTA determined at 1.7- and 2.1-? resolutions, respectively, are reported. Both compounds were held firmly inside the complex formed with four CPGRP-S molecules designated A, B, C, and D. The binding cleft is located at the interface of molecules C and D, which is extendable to the interface of molecules A and C. The interface of molecules A and B is tightly packed, whereas that of molecules B and D forms a wide channel. The hydrophilic moieties of these compounds occupy a common region, whereas hydrophobic chains interact with distinct regions in the binding site. The binding studies showed that CPGRP-S binds to LPS and LTA with affinities of 1.6 × 10(-9) and 2.4 × 10(-8) M, respectively. The flow cytometric studies showed that both LPS- and LTA-induced expression of the proinflammatory cytokines TNF-α and IL-6 was inhibited by CPGRP-S. The results of animal studies using mouse models indicated that both LPS- and LTA-induced mortality rates decreased drastically when CPGRP-S was administered. The recognition of both LPS and LTA, their high binding affinities for CPGRP-S, the significant decrease in the production of LPS- and LTA-induced TNF-α and IL-6, and the drastic reduction in the mortality rates in mice by CPGRP-S indicate its useful properties as an antibiotic agent.  相似文献   

3.
The peptidoglycan recognition protein PGRP-S is an innate immunity molecule that specifically interacts with microbial peptidoglycans and other pathogen-associated molecular patterns. We report here two structures of the unique tetrameric camel PGRP-S (CPGRP-S) complexed with (i) muramyl dipeptide (MDP) at 2.5 Å resolution and (ii) GlcNAc and β-maltose at 1.7Å resolution. The binding studies carried out using surface plasmon resonance indicated that CPGRP-S binds to MDP with a dissociation constant of 10−7 m, whereas the binding affinities for GlcNAc and β-maltose separately are in the range of 10−4 m to 10−5 m, whereas the dissociation constant for the mixture of GlcNAc and maltose was estimated to be 10−6 m. The data from bacterial suspension culture experiments showed a significant inhibition of the growth of Staphylococcus aureus cells when CPGRP-S was added to culture medium. The ELISA experiment showed that the amount of MDP-induced production of TNF-α and IL-6 decreased considerably after the introduction of CPGRP-S. The crystal structure determinations of (i) a binary complex with MDP and (ii) a ternary complex with GlcNAc and β-maltose revealed that MDP, GlcNAc, and β-maltose bound to CPGRP-S in the ligand binding cleft, which is situated at the interface of molecules C and D of the homotetramer formed by four protein molecules A, B, C, and D. In the binary complex, the muramyl moiety of MDP is observed at the C-D interface, whereas the peptide chain protrudes into the center of tetramer. In the ternary complex, GlcNAc and β-maltose occupy distinct non-overlapping positions belonging to different subsites.  相似文献   

4.
Short peptidoglycan recognition protein (PGRP-S) is a member of the innate immunity system in mammals. PGRP-S from Camelus dromedarius (CPGRP-S) is found to be highly potent against bacterial infections. It is capable of binding to a wide range of pathogen-associated molecular patterns (PAMPs) including lipopolysaccharide (LPS), lipoteichoic acid (LTA) and peptidoglycan (PGN). The heparin-like polysaccharides have also been observed in some bacteria such as the capsule of K5 Escherichia coli thus making them relevant for determining the nature of their interactions with CPGRP-S. The binding studies of CPGRP-S with heparin disaccharide in solution using surface plasmon resonance gave a value 3.3×10-7 M for the dissociation constant (Kd). The structure of the heparin bound CPGRP-S determined at 2.8Å resolution revealed the presence of a bound heparin molecule in the binding pocket of CPGRP-S. It was found anchored tightly to the protein with the help of several ionic and hydrogen bonded interactions. Three sulphate groups of heparin S1, S2 and S3 have been found to interact with residues, Arg-31, Lys-90, Thr- 97, Asn-99 Asn-140, Gln-150 and Arg-170 of CPGRP-S. The binding site includes two subsites, S-I and S-II with cleft-like structures. Heparin disaccharide is bound in subsite S-I. Previously determined structures of the complexes of CPGRP-S with LPS, LTA and PGN also showed that their glycan moieties were also held in subsite S-I indicating that heparin disaccharide also represents an important element for the recognition by CPGRP-S.  相似文献   

5.
6.
We previously reported that early night peripheral bacterial lipopolysaccharide (LPS) injection produces phase delays in the circadian rhythm of locomotor activity in mice. We now assess the effects of proinflammatory cytokines on circadian physiology, including their role in LPS-induced phase shifts. First, we investigated whether differential systemic induction of classic proinflammatory cytokines could explain the time-specific behavioral effects of peripheral LPS. Induction levels for plasma interleukin (IL)-1α, IL-1β, IL-6, or tumor necrosis factor (TNF)-α did not differ between animals receiving a LPS challenge in the early day or early night. We next tested the in vivo effects of central proinflammatory cytokines on circadian physiology. We found that intracerebroventricular (i.c.v.) delivery of TNF-α or interleukin IL-1β induced phase delays on wheel-running activity rhythms. Furthermore, we analyzed if these cytokines mediate the LPS-induced phase shifts and found that i.c.v. administration of soluble TNF-α receptor (but not an IL-1β antagonistic) prior to LPS stimulation inhibited the phase delays. Our work suggests that the suprachiasmatic nucleus (SCN) responds to central proinflammatory cytokines in vivo, producing phase shifts in locomotor activity rhythms. Moreover, we show that the LPS-induced phase delays are mediated through the action of TNF-α at the central level, and that systemic induction of proinflammatory cytokines might be necessary, but not sufficient, for this behavioral outcome.  相似文献   

7.
We previously reported that early night peripheral bacterial lipopolysaccharide (LPS) injection produces phase delays in the circadian rhythm of locomotor activity in mice. We now assess the effects of proinflammatory cytokines on circadian physiology, including their role in LPS-induced phase shifts. First, we investigated whether differential systemic induction of classic proinflammatory cytokines could explain the time-specific behavioral effects of peripheral LPS. Induction levels for plasma interleukin (IL)-1α, IL-1β, IL-6, or tumor necrosis factor (TNF)-α did not differ between animals receiving a LPS challenge in the early day or early night. We next tested the in vivo effects of central proinflammatory cytokines on circadian physiology. We found that intracerebroventricular (i.c.v.) delivery of TNF-α or interleukin IL-1β induced phase delays on wheel-running activity rhythms. Furthermore, we analyzed if these cytokines mediate the LPS-induced phase shifts and found that i.c.v. administration of soluble TNF-α receptor (but not an IL-1β antagonistic) prior to LPS stimulation inhibited the phase delays. Our work suggests that the suprachiasmatic nucleus (SCN) responds to central proinflammatory cytokines in vivo, producing phase shifts in locomotor activity rhythms. Moreover, we show that the LPS-induced phase delays are mediated through the action of TNF-α at the central level, and that systemic induction of proinflammatory cytokines might be necessary, but not sufficient, for this behavioral outcome. (Author correspondence: )  相似文献   

8.
《Cytokine》2014,67(2):127-132
In tegumentary leishmaniasis caused by Leishmania braziliensis, there is evidence that increased production of IFN-γ, TNF-α and absence of IL-10 is associated with strong inflammatory reaction and with tissue destruction and development of the lesions observed in cutaneous leishmaniasis (CL) and mucosal leishmaniasis (ML). We evaluate the role of regulatory cytokines and cytokine antagonists in the downregulation of immune response in L. braziliensis infection. Peripheral blood mononuclear cells from CL and ML were stimulated with soluble Leishmania antigen in the presence or absence of regulatory cytokines (IL-10, IL-27 and TGF-β) or antagonists of cytokines (α-TNF-α and α-IFN-γ). Cytokines production (IL-10, IL-17, TNF-α and IFN-γ) was measured by ELISA. IL-10 and TGF-β downmodulate TNF-α and IL-17 production, whereas IL-27 had no effect in the production of TNF-α, IFN-γ and IL-17 in these patients. Neutralization of TNF-α decreased IFN-γ level and the neutralization of IFN-γ decreased TNF-α level and increased IL-10 production. This study demonstrate that IL-10 and TGF-β are cytokines that appear to be more involved in modulation of immune response in CL and ML patients. IL-10 might have a protective role, since the neutralization of IFN-γ decreases the production of TNF-α in an IL-10-dependent manner.  相似文献   

9.
10.
We evaluated the effects of a 50% methanol extract of Citrus unshiu powder (MEC) on cytokines in peripheral blood mononuclear cells (PBMCs) obtained from patients with seasonal allergic rhinitis to cedar pollen. The levels of cytokines, such as TNF-α, IFN-γ, IL-2, IL-4, IL-5, IL-10, IL-12 (p70), IL-13, and GM-CSF, produced by pollen-stimulated PBMC were measured. We found that MEC suppressed pollen-induced TNF-α release and increased IFN-γ release from PBMCs. The results suggest that Citrus unshiu powder has an immunomodulatory effect in vitro and that its use could improve seasonal allergic rhinitis symptoms.  相似文献   

11.
Recent studies have shown that some flavonoids are modulators of proinflammatory cytokine production. In this study, velutin, a unique flavone isolated from the pulp of açaí fruit (Euterpe oleracea Mart.), was examined for its effects in reducing lipopolysaccharide-induced proinflammatory cytokine tumor necrosis factor (TNF)-α and interleukin (IL)-6 production in RAW 264.7 peripheral macrophages and mice peritoneal macrophages. Three other structurally similar and well-studied flavones, luteolin, apigenin and chrysoeriol, were included as controls and for comparative purposes. Velutin exhibited the greatest potency among all flavones in reducing TNF-α and IL-6 production. Velutin also showed the strongest inhibitory effect in nuclear factor (NF)-κB activation (as assessed by secreted alkaline phosphatase reporter assay) and exhibited the greatest effects in blocking the degradation of inhibitor of NF-κB as well as in inhibiting mitogen-activated protein kinase p38 and JNK phosphorylation; all of these are important signaling pathways involved in production of TNF-α and IL-6. The present study led to the discovery of a strong anti-inflammatory flavone, velutin. This compound effectively inhibited the expression of proinflammatory cytokines TNF-α and IL-6 in low micromole levels by inhibiting NF-κB activation and p38 and JNK phosphorylation.  相似文献   

12.
Fracture healing is regulated by proinflammatory mediators such as tumor necrosis factor-α (TNF-α), which poses influence on the balance between bone formation and remodeling. And the diabetes is thought to contribute to the delayed diabetic fracture healing. In the present study, we examined the promotion to proinflammatory cytokines and chemokines in type 2 diabetes mellitus (T2DM) patients with bone fractures, and then evaluated the promotion to TNF-α by the high glucose treatment in human osteoblast-like MG-63 cells and the regulatory role of the promoted TNF-α on the MG-63 cell apoptosis. It was demonstrated that there were significantly-upregulated high-sensitivity C-reactive protein (hsCRP) TNF-α, IL-1β, IL-6, IFN-γ-inducible protein 10 (IP-10) and RANTES in T2DM patients with bone fracture. And the promotion to TNF-α and IL-1β was confirmed in vitro in both mRNA and protein levels in high glucose-treated MG-63 cells. And either TNF-α or high glucose reduced the viability of MG-63 cells, promoted apoptosis and upregulated apoptosis-associated markers, such as released cytochrome c, cleaved caspase 3 and lyzed PARP. Moreover, there was a synergistic effect between TNF-α and high glucose. The viability reduction and the apoptosis induction of MG-63 cells were significantly higher in the group with both TNF-α and high glucose treatments, than in the group with singular TNF-α treatment. In conclusion, our study demonstrated that proinflammatory cytokines and chemokines were promoted in T2DM patients with bone fracture or in osteoblasts by the high glucose stimulation. TNF-α and high glucose synergistically reduced the viability and induced the apoptosis in the osteoblast-like MG-63 cells in vitro. It implies the significant regulatory role of TNF-α in the delayed fracture healing in T2DM.  相似文献   

13.
Kim KH  Kim DI  Kim SH  Jung EM  Kang JH  Jeung EB  Yang MP 《Cytokine》2011,56(2):224-230
Conjugated linoleic acid (CLA) can stimulate or inhibit immune cell function, and among CLA isomers, trans-10, cis-12 (t10c12)-CLA was shown to participate in the modulation of pro- or anti-inflammatory cytokine secretion. The objective of this study was to examine the effect of t10c12-CLA on tumor necrosis factor (TNF)-α production by lipopolysaccharide (LPS)-stimulated porcine peripheral blood mononuclear cells (PBMCs). In addition, we determined whether these effects were associated with the induction of interleukin (IL)-10. Treatment of LPS-unstimulated porcine PBMCs with t10c12-CLA increased both TNF-α expression and IL-10 production. However, treatment of LPS-stimulated porcine PBMCs with t10c12-CLA suppressed TNF-α production and increased the levels of IL-10. Furthermore, treatment of LPS-stimulated porcine PBMCs with IL-10 suppressed the production of TNF-α. The effects of t10c12-CLA on TNF-α expression by both LPS-naïve and LPS-stimulated PBMCs were inhibited by IL-10 treatment. The suppressive effects of t10c12-CLA on TNF-α production by LPS-stimulated porcine PBMCs were inhibited by an anti-IL-10 polyclonal antibody. These findings suggest that t10c12-CLA has an immunostimulatory effect on porcine PBMCs mediated via the up-regulation of TNF-α production, and an anti-inflammatory effect in LPS-stimulated PBMCs mediated via the down-regulation of TNF-α production, and that both is likely to be associated with the induction of IL-10.  相似文献   

14.
不同运动方式对COPD 缓解期患者血清细胞因子的影响   总被引:1,自引:0,他引:1  
目的:探讨IL-1、IL-6、TNF-α在COPD缓解期气道炎症中的作用及运动训练对COPD患者血清细胞因子的影响,为COPD患者制定最佳运动模式提供依据。方法:对55例临床缓解期的COPD患者进行为期12周运动训练,运动训练前后采用双抗体夹心ABC-ELISA法检测患者血清中细胞因子值,并与60名健康老年人比较。结果:COPD缓解期患者运动训练前,血清中IL-1、IL-6、TNF-α值均显著高于正常老年人组(P<0.01);经运动训练后,IL-1、TNF-α值显著下降(P<0.01),且不同运动训练方法,血清细胞因子变化幅度不同,以太极拳训练组IL-1、TNF-α下降的幅度最大(P<0.01)。结论:IL-1、IL-6、TNF-α参与了COPD缓解期气道慢性炎症反应,运动训练对致炎因子有下调作用,且太极拳运动训练下调效果较为明显。  相似文献   

15.
Preeclampsia is associated with systemic inflammation and increased expression of placental Th1-cytokines. IL-10 and calcitriol inhibit proinflammatory cytokines expression in human placenta helping to fetal allograft toleration. Regulation of placental IL-10 by calcitriol and Th-1 cytokines has not yet been fully elucidated. Since it is believed that calcitriol promotes a shift from a Th1- to a Th2 profile, we hypothesized that it would stimulate IL-10 in a normal and an inflammatory scenario to conjointly restrain inflammation. Therefore, we investigated calcitriol effects upon IL-10 expression in cultured human trophoblasts obtained from normal (NT) and preeclamptic (PE) pregnancies. Similar studies in the presence of TNF-α (as an inflammatory stressor) were also performed. Calcitriol dose-dependently inhibited IL-10 expression in NT, PE and TNF-α-challenged trophoblasts (P<0.05). This effect was prevented by a vitamin D receptor (VDR) antagonist. IL-10 expression was significantly stimulated by TNF-α and IL-1β, inhibited by IFN-γ and was not affected by IL-6. Finally, calcitriol inhibited TNF-α and IL-1β stimulation upon IL-10. In summary, in cultured human trophoblasts, calcitriol down-regulates IL-10 expression under normal as well as under natural and experimental inflammatory conditions. This effect is mediated by the VDR and might involve direct inhibition of TNF-α. In view of these and previous results it seems that in placenta calcitriol suppresses both Th1- and Th2 cytokines while undertakes the anti-inflammatory effects of IL-10 by itself, since both factors exert this task redundantly. The regulation of IL-10 by IFN-γ suggests that this cytokine could be a viable candidate to explain low IL-10 levels in preeclampsia.  相似文献   

16.
Peptidoglycan (PG) N-acetyl muramic acid (MurNAc) O-acetylation is widely spread in gram-positive bacteria and is generally associated with resistance against lysozyme and endogenous autolysins. We report here the presence of O-acetylation on N-acetylglucosamine (GlcNAc) in Lactobacillus plantarum PG. This modification of glycan strands was never described in bacteria. Fine structural characterization of acetylated muropeptides released from L. plantarum PG demonstrated that both MurNAc and GlcNAc are O-acetylated in this species. These two PG post-modifications rely on two dedicated O-acetyltransferase encoding genes, named oatA and oatB, respectively. By analyzing the resistance to cell wall hydrolysis of mutant strains, we showed that GlcNAc O-acetylation inhibits N-acetylglucosaminidase Acm2, the major L. plantarum autolysin. In this bacterial species, inactivation of oatA, encoding MurNAc O-acetyltransferase, resulted in marked sensitivity to lysozyme. Moreover, MurNAc over-O-acetylation was shown to activate autolysis through the putative N-acetylmuramoyl-L-alanine amidase LytH enzyme. Our data indicate that in L. plantarum, two different O-acetyltransferases play original and antagonistic roles in the modulation of the activity of endogenous autolysins.  相似文献   

17.
Journal of Evolutionary Biochemistry and Physiology - Interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) are the major proinflammatory cytokines. Cytokine receptors are...  相似文献   

18.
β-d -Mannuronic acid (M2000), a novel non-steroidal anti-inflammatory drug (NSAID) with immunosuppressive properties, has been previously shown to exhibit potential therapeutic effects on autoimmune diseases. Immunosuppression therapy has been a standard approach for myelodysplastic syndrome (MDS) for many years. We evaluated the effect of M2000 on isolated peripheral blood mononuclear cells (PBMCs) from patients with MDS. The PBMCs were isolated from 13 patients with MDS and 13 normal donors. The cells were then treated with low, moderate, and high doses of M2000 and diclofenac as a control group. The level of interleukin (IL)-6, tumor necrosis factor alpha (TNF-α), IL-3, granulocyte colony-stimulating factor (G-CSF) gene expression and the serum level of IL-6 and TNF-α production were evaluated by real-time polymerase chain reaction and enzyme-linked immunosorbent assay methods, respectively. Our findings indicated a significant reduction in the production of IL-6 and TNF-α as inflammatory cytokines. Furthermore, the level of G-CSF gene expression was significantly increased. In conclusion, M2000, a newly designed NSAID, has a remarkable effect on isolated PBMC in patients with MDS, which might bring a potential hope for its oral administrations in these patients.  相似文献   

19.
Type 2 diabetes mellitus (T2DM) features insulin resistance, hyperglycemia, dyslipidemia, overproduction of inflammatory cytokines, and systemic oxidative stress. Here, heat shock proteins Hsp70 and Hsp 90, adiponectin, and heme oxygenase-1 (HO-1, Hsp32) are profiled in peripheral blood mononuclear cells (PBMC) and serum from 25 T2DM patients and 25 healthy control subjects. Cells cultured with phorbol 12-myristate 13-acetate/ionomycin were evaluated by three-color flow cytometry for immunophenotypic biomarkers. Plasma HO-1, Hsp, and adiponectin levels were assayed by enzyme-linked immunosorbent assay (ELISA). Relative to healthy controls, T2DM patients exhibited significantly elevated plasma Hsp70, and representation of T helper immunophenotypes activated to express inflammatory cytokines, including CD4+ IFN-γ+, CD4+ TNF-α+, CD4+ IL-6+, CD4+ IL-1β+ T cells, significantly lower representation of CD4+ IL-10+ T cells, plasma adiponectin and cell-associated HO-1 expression—with no significant differences in plasma Hsp90 between T2DM and healthy controls. Plasma HO-1 and adiponectin in T2DM patients inversely correlated with TNF-α and showed inverse correlation between serum LDL and plasma HO-1. Moreover, TNF-α and Hsp90 in T2DM patients correlated positively with fasting blood glucose (FBG). These results demonstrate correlation between potentially pathogenic T cells, HO-1, and adiponectin, additionally revealing a T helper (Th)1-related character of T2DM immunopathogenesis, suggesting potential for novel T cell-related management strategies for T2DM and related co-morbidities.  相似文献   

20.
Peptidoglycan recognition proteins (PGRPs) are part of the innate immune system. The 19 kDa Short PGRP (PGRP-S) is one of the four mammalian PGRPs. The concentration of PGRP-S in camel (CPGRP-S) has been shown to increase considerably during mastitis. The structure of CPGRP-S consists of four protein molecules designated as A, B, C and D forming stable intermolecular contacts, A–B and C–D. The A–B and C–D interfaces are located on the opposite sides of the same monomer leading to the the formation of a linear chain with alternating A–B and C–D contacts. Two ligand binding sites, one at C–D contact and another at A–B contact have been observed. CPGRP-S binds to the components of bacterial cell wall molecules such as lipopolysaccharide (LPS), lipoteichoic acid (LTA), and peptidoglycan (PGN) from both Gram-positive and Gram-negative bacteria. It also binds to fatty acids including mycolic acid of the Mycobacterium tuberculosis (Mtb). Previous structural studies of binary complexes of CPGRP-S with LPS and stearic acid (SA) have shown that LPS binds to CPGRP-S at C–D contact (Site-1) while SA binds to it at the A–B contact (Site-2). The binding studies using surface plasmon resonance showed that LPS and SA bound to CPGRP-S in the presence of each other. The structure determination of the ternary complex showed that LPS and SA bound to CPGRP-S at Site-1 and Site-2 respectively. LPS formed 13 hydrogen bonds and 159 van der Waals contacts (distances ≤4.2 Å) while SA formed 56 van der Waals contacts. The ELISA test showed that increased levels of productions of pro-inflammatory cytokines TNF-α and IFN-γ due to LPS and SA decreased considerably upon the addition of CPGRP-S.  相似文献   

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