肠易激综合征患者血浆脑肠肽水平的变化

脑肠肽作为一类具有神经递质和激素双重功能的小分子多肽,在肠易激综合征（IBS）的发病机制中起重要作用.目的：研究血管活性肠肽（VIP）,神经肽Y（NPY）和神经降压素（NT）水平在IBS患者血浆中的变化及其临床意义.方法：根据RomeⅡ标准纳入IBS患者36例,其中腹泻为主型IBS（D-IBS）24例,便秘为主型IBS（C-IBS）12例,同时纳入正常对照者10名.采用放射免疫测定分别检测受试者血浆VIP、NPY和NT水平.结果：D-IBS患者血浆VIP水平显著高于正常对照组（P＜0.05）,而C-IBS患者血浆VIP水平与正常对照组比较无显著差异（P＞0.05）;D-IBS和C-IBS患者血浆NPY水平均显著低于正常对照组（P＜0.05和P＜0.01）,其中C-IBS患者又显著低于D-IBS患者（P＜0.05）;D-IBS和C-IBS患者血浆NT水平均显著高于正常对照组（P＜0.05）,但两亚型间比较无显著差异（P＞0.05）.结论：IBS患者血浆脑肠肽水平与腹泻或便秘症状有一定的联系,表现为D-IBS和C-IBS患者的血浆NT水平均显著升高,而NPY和VIP水平因IBS亚型的不同而有差异.脑肠肽作为调节胃肠运动功能和感觉功能的重要因素,可能与IBS的发生、发展有必然的内在联系.     

Efficient induction of cytotoxic T lymphocytes specific for severe acute respiratory syndrome (SARS)-associated coronavirus by immunization with surface-linked liposomal peptides derived from a non-structural polyprotein 1a

Spike and nucleocapsid are structural proteins of severe acute respiratory syndrome (SARS)-associated coronavirus (SARS-CoV) and major targets for cytotoxic T lymphocytes (CTLs). In contrast, non-structural proteins encoded by two-thirds of viral genome are poorly characterized for cell-mediated immunity. We previously demonstrated that nucleocapsid-derived peptides chemically coupled to the surface of liposomes effectively elicited SARS-CoV-specific CTLs in mice. Here, we attempted to identify HLA-A*0201-restricted CTL epitopes derived from a non-structural polyprotein 1a (pp1a) of SARS-CoV, and investigated whether liposomal peptides derived from pp1a were effective for CTL induction. Out of 30 peptides predicted on computational algorithms, nine peptides could significantly induce interferon gamma (IFN-γ)-producing CD8⁺ T cells in mice. These peptides were coupled to the surface of liposomes, and inoculated into mice. Six liposomal peptides effectively induced IFN-γ-producing CD8⁺ T cells and seven liposomal peptides including the six peptides primed CTLs showing in vivo killing activities. Further, CTLs induced by the seven liposomal peptides lysed an HLA-A*0201 positive cell line expressing naturally processed, pp1a-derived peptides. Of note, one of the liposomal peptides induced high numbers of long-lasting memory CTLs. These data suggest that surface-linked liposomal peptides derived from pp1a might offer an efficient CTL-based vaccine against SARS.     

Peptide mimotopes of rabies virus glycoprotein with immunogenic activity

A random constrained hexapeptide phage display library (Cys-6aa-Cys) was screened with purified neutralizing human anti-rabies virus IgG antibodies (hRABVIgG) to identify peptides that correspond to or mimic natural epitopes on rabies virus glycoprotein (RABVG) and to investigate their immunogenicities in vivo. After four rounds of biopanning, 20 phage clones randomly selected for their specificity to hRABVIgG, effectively blocked the binding of the inactive rabies virus (RABV) to hRABVIgG. The phage clones were sequenced and the deduced amino acid sequences were derived (C-KRDSTW-C; C-KYLWSK-C; C-KYWLSR-C; C-KYWWSK-C; C-KYAWSR-C; C-KYSMSK-C). Alignments to the amino acid sequence of RABVG showed good match with the antigenic site III (at 330–338 aa), indicating that the hRABVIgG antibodies most likely recognize preferentially this antigenic site. The selected mimotopes were able to inhibit the interactions of the hRABVIgG antibodies with RABV in a dose-dependent manner. Subcutaneous administration of phageKRDSTW expressing the RABVG site III mimotope induced an RABVG-specific IgG response in BALB/c mice. The results indicated that peptide mimotopes when displayed on phages, are accessible to the mice immune system to trigger a humoral response and to induce IgG production. The RABVG site III mimotope (C-KRDSTW-C) would provide a new and promising concept for the development of rabies vaccine.     

A universal epitope-based influenza vaccine and its efficacy against H5N1

Previous studies have shown that a recombinant vaccine expressing four highly conserved influenza virus epitopes has a potential for a broad spectrum, cross-reactive vaccine; it induced protection against H1, H2 and H3 influenza strains. Here, we report on the evaluation of an epitope-based vaccine in which six conserved epitopes, common to many influenza virus strains are expressed within a recombinant flagellin that serves as both a carrier and adjuvant. In an HLA-A2.1 transgenic mice model, this vaccine induced both humoral and cellular responses and conferred some protection against lethal challenge with the highly pathogenic H5N1 avian influenza strain. Hence, it is expected to protect against future strains as well. The data presented, demonstrate the feasibility of using an array of peptides for vaccination, which might pave the way to an advantageous universal influenza virus vaccine that does not require frequent updates and/or annual immunizations.     

Structural optimisation of a conformational epitope improves antigenicity when expressed as a recombinant fusion protein

A conformationally restricted B cell epitope has been identified as a potential safe vaccine candidate from the major group A streptococcal virulence factor, the M protein. To maintain α-helical secondary structure, the minimal epitope is flanked with heterologous sequences to produce the chimeric vaccine candidate called J14. As a strategy toward developing an affordable multivalent GAS vaccine, we have expressed J14 recombinantly with a second GAS protective antigen H12 (rJ14H12). When administered to mice sub-cutaneously, the fusion protein stimulated a strong serum IgG response to the H12 component, but J14 was poorly immunogenic. To increase the immunogenicity of J14 when expressed with the model fusion partner, amino acid modifications were made to the initial recombinant J14 construct to produce rJJo. These changes stabilised the α-helical conformation of the recombinant antigen as assessed by circular dichroism. Mice immunised with rJJoH12, the fusion protein incorporating JJo, effectively stimulated a humoral response to both of the included antigens. These data support the feasibility of developing a multivalent vaccine incorporating the conformationally restricted protective antigen J14.     

Small Nogo-66-binding peptide promotes neurite outgrowth through RhoA inhibition after spinal cord injury

Abortive regeneration in the adult mammalian central nervous system (CNS) is partially mediated through CNS myelin proteins, among which Nogo-A plays an important role. Nogo-66, which is located at the C-terminus of Nogo-A, inhibits axonal regrowth through the Nogo-66/NgR signalling pathway. In this study, two small peptides were tested in a neurite outgrowth assay and spinal cord injury (SCI) model to examine the effects of these molecules on the inhibition of Nogo-66/NgR signalling. PepIV was selected from a phage display peptide library as a Nogo-66 binding molecule. And PepII was synthesized as a potential NgR antagonist. The results indicated that PepIV and PepII decrease the mRNA levels of the small GTPase RhoA and partially neutralize CNS myelin inhibition to cultured cerebellar granule cells (CGCs). Moreover, treatment with both peptides was propitious to maintaining residual axons after SCI, thereby promoting regeneration and locomotion recovery. Because RhoA plays a role in stabilizing the cytoskeleton in growth cones and axons, enhanced neurite outgrowth might reflect a decrease in RhoA expression through PepIV and PepII treatment. Moreover, PepIV induced lower RhoA mRNA expression compared with PepII. Therefore, PepIV could block Nogo-66/NgR signalling and reduce RhoA mRNA level, and then contribute to neuronal survival and axonal regrowth after SCI, showing its ability to reverse CNS myelin inhibition to regeneration. Furthermore, selected small peptide might cover some unknown active sites on CNS myelin proteins, which could be potential targets for improving neurite outgrowth after injury.     

Experimental immunotherapeutic approaches for atherosclerosis

Therapeutic options in atherosclerosis have largely been limited to the control of risk factors, such as hypercholesterolemia, hypertension, or diabetes. However, atherosclerosis is a chronic inflammatory disease in which dyslipidemia and inflammation are equally involved in disease pathogenesis. Moreover, abundant epidemiological and experimental evidence point to an important modulatory role of innate and adaptive immunity in atherogenesis, providing novel therapeutic targets for this disease. Indeed, there is now accumulating data in animal models demonstrating the potential for immunotherapeutic approaches to treat atherosclerosis. These include both general and antigen-specific ways of modulating immune functions, and they show great promise for the development of alternative and/or adjuvant therapies for atherosclerosis.     

Comparison of the postprandial release of peptide YY and proglucagon-derived peptides in the rat

Endocrine L-cells of the distal intestine synthesize both peptide YY (PYY) and proglucagon-derived peptides (PGDPs), whose release has been reported to be either parallel or selective. Here we compare the release mechanisms of PYY, glucagon-like peptide-1 (GLP-1), and oxyntomodulin-like immunoreactivity (OLI) in vivo. Anaesthetized rats were intraduodenally (ID) given either a mixed semi-liquid meal or oleic acid, or they received oleic acid or short chain fatty acids (SCFA) intracolonically (IC). The ID meal released the three peptides with a similar time-course (peak at 30 min); ID oleic acid produced a progressive release of PYY and OLI, while GLP-1 release was less. IC oleic acid or SCFA released smaller (but significant) amounts of PYY but no OLI or GLP-1. Hexamethonium inhibited most of the response to the ID meal and ID oleic acid, but did not change the PYY response to IC oleic acid. N ^G -nitro-l-arginine methyl ester (l-NAME, a nitric oxide synthase inhibitor) inhibited meal-induced PYY release and left OLI and GLP-1 unaffected. BW10 (a gastrin-releasing peptide antagonist) had no effect on the meal-induced release of either peptide. These results suggest a parallel initial release of PYY, OLI and GLP-1 after the ID meal, or oleic acid, by an indirect mechanism triggered in the proximal bowel, using nicotinic synapses, and involving nitric oxide release for PYY and an unknown mediator for PGDPs. For PYY there is a later phase of peptide release, probably induced by direct contact between nutrients and colonic L-cells. Received: 8 January 1999 / Received after revision: 25 March 1999 / Accepted: 26 April 1999     

LT adjuvant modulates epitope specificity and improves the efficacy of murine antibodies elicited by sublingual vaccination with the N-terminal domain of Streptococcus mutans P1

In this study, we evaluated the immunogenicity, protective efficacy and peptide-based immune signatures of antibodies raised in mice after sublingual immunization with a recombinant form of the P1 (aka AgI/II, PAc) adhesin (P1_39-512) of Streptococcus mutans, a major etiological agent of dental caries. Sublingual administration of P1_39-512 in combination with the mucosal adjuvant LTK4R (a derivative of heat-labile LT toxin) induced strong and long-lasting systemic and mucosal immune responses. Incorporation of the adjuvant resulted in an enhancement of the anti-adhesive and anti-colonization activity against S. mutans as evaluated both under in vitro and in vivo conditions. Incorporation of the adjuvant to the vaccine formulation also changed the epitope specificity of the induced antibodies as determined by immunological signatures of sera collected from vaccinated mice. Use of a peptide microarray library led to the identification of peptide targets recognized by antibodies in serum samples with enhanced anti-adhesive effects. Altogether, the results presented herein showed that the sublingual administration of a P1-based subunit vaccine represents a promising approach for the prevention of dental caries caused by S. mutans. In addition, the present study disclosed the role of adjuvants on the epitope specificity and functionality of antibodies raised by subunit vaccines.     

降钙素基因相关肽对c-kit+心脏干细胞生存活力的影响

目的探讨降钙素基因相关肽(CGRP)对缺氧状态下c-kit~+心脏干细胞(c-kit~+CSC)生存活力的影响及其可能的机制。方法体外建立细胞缺氧模型,实验随机分为缺氧细胞组、CGRP+缺氧细胞组、CGRP+CGRP8-37+缺氧细胞组和对照组(不缺氧细胞);通过CCK-8法检测细胞的活力,采用流式细胞仪和线粒体膜电位法来检测细胞凋亡。结果在缺氧状态下,缺氧细胞组细胞增殖活力较对照组下降,CGRP作用缺氧细胞后不同时间点,与缺氧细胞组比较,细胞增殖活力均增加(P0.05),尤其以30 min和60 min最为明显;与CGRP+缺氧细胞组比较,CGRP+CGRP8-37+缺氧细胞组在30 min和60 min细胞增殖活力明显下降(P0.05)。流式细胞仪结果显示:与对照组比较,缺氧细胞组早期凋亡率最高(P0.05);与缺氧细胞组比较,CGRP+缺氧细胞组早期凋亡率降低(P0.05);与CGRP+缺氧细胞组比较,CGRP+CGRP8-37+缺氧细胞组早期凋亡率增高(P0.05)。线粒体膜电位结果显示:与缺氧细胞组比较,CGRP+缺氧细胞组红色荧光/绿色荧光比值增高(P0.05);与CGRP+缺氧细胞组比较,CGRP+CGRP8-37+缺氧细胞组红色荧光/绿色荧光比值降低(P0.05)。结论 CGRP能够促进缺氧状态下c-kit~+CSC增殖存活,抑制细胞早期凋亡。