TLR9激动剂对约氏疟原虫体液免疫记忆的影响

为探讨TLR9激动剂对疟疾体液免疫记忆的影响,用非致死型约氏疟原虫感染BALB/c小鼠,感染前2 d注射TLR9激动剂CpGl826,90 d后进行二次感染。薄血膜染色法观察红细胞感染率,流式细胞术检测脾细胞悬液中记忆性和活化性B细胞百分比,双夹心ELISA法检测特异性抗体水平。结果显示,二次感染前,TLR9激动剂处理鼠记忆性和活化性B细胞以及抗体水平略高于对照组;二次感染后,其再感染发生率和虫血症水平均略低于对照组;活化性B细胞和抗体以及记忆性B细胞也分别于二次感染后1 d和3 d出现了有意义的升高,且升高幅度均略高于对照组。表明TLR9激动剂对约氏疟原虫感染后体液免疫记忆的建立和维持有一定促进作用。     

TLR4激活剂对约氏疟原虫感染早期免疫应答的影响

通过外源性给予LPS,探讨TLR4在疟疾感染早期免疫应答的作用特点及其免疫调节作用。通过Plasmodium yoelii 17XL感染的BALB/c小鼠建立鼠疟模型并在感染前给予LPS,于感染第0、3和5天制备脾细胞悬液,通过流式细胞术检测脾细胞悬液中TLR4+DCs和Tregs百分含量;ELISA方法检测脾细胞培养上清中IFN-γ和IL-10水平。结果显示,LPS处理能够显著延长宿主生存期,降低原虫血症水平,同时显著提升脾上清中的IFN-γ水平,降低抑炎性细胞因子IL-10水平。在感染早期,LPS处理可诱导Th1型免疫应答的有效建立,明显遏制P.y 17XL红内期疟原虫的感染进程。     

大蒜素对致死型约氏疟原虫鼠疟模型CD4+活化/凋亡T细胞的影响

探讨大蒜素对致死型约氏疟原虫(Plasmodium yoelii 17XL,P.y 17XL)感染BALB/c小鼠T细胞免疫应答的影响。P.y 17XL感染后第0~2天每日口服给予不同浓度大蒜素(3 mg/kg或9 mg/kg)处理;动态监测各组小鼠原虫血症水平和生存期;感染后第0天、第3天和第5天无菌提取小鼠脾细胞,FACS检测小鼠活化T细胞(CD4~+CD69~+)、凋亡CD4~+T细胞(7AAD~-Annexin V~+)数量变化;ELISA检测脾细胞培养上清中IFN-γ和TNF-α的水平。结果显示:与NC组相比,大蒜素处理组能降低感染小鼠的原虫血症水平,延长生存期。大蒜素处理能提高感染小鼠活化T细胞的数量,降低凋亡T细胞数量,并能提高脾细胞培养上清中IFN-γ和TNF-α的水平。大蒜素能在感染早期促使宿主建立有效的Th1免疫应答,从而抑制红内期P.y 17XL疟原虫感染进程。     

硝喹对约氏疟原虫红内期细胞色素氧化酶的影响

给感染约氏疟原虫的小鼠,灌服硝喹后,用细胞色素氧化酶组织化学方法处理红细胞,透射电交易观察疟原虫。结果发现,约氏疟原虫红内期线粒体内存在细胞色素氧化酸疼 ,硝喹不能抑制该酶的活性。说明约氏疟原虫内细胞色素氧化酶不是硝喹的起始作用点。     

不同毒力疟原虫感染早期根治性治疗对免疫记忆形成影响的研究

为探讨不同毒力疟原虫感染早期根治性治疗对免疫记忆形成的影响,用致死型和非致死型约氏疟原虫感染DBA/2小鼠,感染后3 d进行根治性治疗,并于初次感染后90 d进行再感染。通过计数红细胞感染率和检测再感染前后不同时间点脾细胞中记忆性T、B细胞的百分含量后发现,再感染后2组小鼠均出现了短暂的低水平虫体血症;再感染前小鼠脾细胞中记忆性T、B细胞百分率均略高于正常鼠;但再感染后均出现了有意义的升高;在每一相同检测时间点,2组小鼠的虫体血症水平和记忆性T、B细胞百分率均无显著差异。这表明,不同毒力疟原虫感染早期的根治性治疗可使宿主产生水平相近的免疫记忆,再感染可促进免疫记忆的形成。     

Tim-1分子在约氏疟原虫感染模型中的表达分析

Tim-1分子表达在T细胞和调节性B细胞表面,具有促进Th2应答的作用。为探讨Tim-1分子在抗疟疾免疫应答中的作用,利用致死型约氏疟原虫(Plasmodium yoelii)感染鼠疟模型研究了Tim-1分子表达与小鼠感染结局和免疫应答模式的关系。结果显示,BALB/c小鼠对P.yoelii易感,在感染后6～7 d全部死亡,感染后第3、5天脾内细胞因子IFN-γmRNA水平明显低于对P.yoelii抵抗的DBA2小鼠,而脾IL-10 mRNA水平显著高于DBA2小鼠。BALB/c小鼠脾内Tim-1+T、B细胞百分比在感染后第3、5天显著升高,而DBA2小鼠感染前后脾内Tim-1+T、B细胞百分比没有显著变化。结果提示,Tim-1分子参与抗P.yoelii免疫应答的调节,可能与易感鼠产生高水平Th2型细胞因子有关。     

约氏疟原虫红外期体外培养的研究

通过药物二乙基亚硝胺（ＤＥＮ）诱发大鼠肝癌，取肝癌白色结节用胶原酶消化，体外培养建立肝癌细胞系，筛选出对约氏疟原虫子孢子敏感的大鼠肝癌细胞系，建立了大鼠肝癌细胞－约氏疟原虫体外培养系统。纸氏疟原虫子孢子接种单层培养的肝癌细胞，４８ｈ可见红外期裂殖体，７２ｈ后培养细胞胰酶消化，消化下的细胞及培养上清一半离心，悬液接种健康小鼠，可使之感染疟疾。     

大鼠营养不良对约氏疟原虫子孢子侵入及其红外期发育的影响

人类的疟疾流行史表明,处于饥饿或营养不良状态下的人群,其疟疾发病率较低,临床症状较轻,动物实验证明,疟原虫红内期的发育对宿主饲料营养成份的依赖性非常明显。但宿主营养状态对子孢子侵入和红外期发育的影响尚未见有报道。本文观察了大鼠在营养不良条件下对约氏疟原虫子孢子侵入及红外期发育的影响。 将感染约氏疟原虫(Plasmodium y.yoelii)BY265 后14天的斯氏按蚊一批,剪去腹部,研磨,用     

约氏疟原虫蚊期体外培养：动合子和动合子形成的扫描电镜观察

为了开展疟疾防治以及疟原虫生物学的研究,进一步了解在体外培养中疟原虫的发育规律、形态结构等生物学特性,我们于1985年对离体培养的约氏疟原虫约氏亚种动合子和动合子形成进行了扫描电镜的观察。 材料和方法 约氏疟原虫约氏亚种(Plasmalium yoelii yoelii)用血传和蚊传保种。在昆明株小鼠(KM/AMS)体内多次血传做为供血鼠。C_(57)6JB/ax 小鼠保种。定期感染斯氏按蚊(Anpheles stephensis)MEM     

约氏疟原虫红外期成熟裂殖体的超微结构研究

用细胞色素氧化酶组织化学方法处理感染了约工疟原虫子孢子的大鼠肝脏,通过透射电镜研究红外期裂殖体的超微结构。在接种子孢子后４８小时的标本中发现一成熟裂殖体,外周仍由一寄生虫质膜包裹,膜下有许多小泡,粗面内质肉、圆形或蚕豆形具明显嵴的线粒体,以及大量成熟裂殖子。     

Plasmodium yoelii: Correlation of TEP1 with mosquito melanization induced by nitroquine

The antimalarial drug nitroquine is not only an effective antimalarial drug, it is also able to induce the melanization of Plasmodium species. However, the molecular mechanisms of the recognition reaction induced by this drug remain unclear. Silencing of thioester-containing protein-1 (TEP1) significantly compromised the ability of Anopheles gambiae to melanize the Plasmodium, leading to investigation of the involvement of A. stephensi TEP1 in melanization induced by nitroquine. This study shows that (1) binding of AsTEP1 to oocysts, especially melanized oocysts, (2) after ingestion of anti-AsTEP1 antibody, the melanization rate in antibody-treated mosquitoes are significantly lower than in control mosquito (p < 0.05). The results suggest that nitroquine is able to induce Plasmodium recognition by TEP1, possibly triggering the resulting melanotic encapsulation. Further elucidation of the molecular mechanisms of mosquito immunity induced by antimalarial drugs will provide theoretical evidence for the use of antimalarial drugs, and a meaningful pathway for the design of novel antimalarial drugs.     

遗传位点影响小鼠对约氏疟原虫易感性的研究

探讨Listr1遗传位点影响小鼠对疟原虫易感性的可能性及其初步作用机制。致死型约氏疟原虫(Plasmodium yoelii 17XL,P.y17XL)感染C.B6By Listr1小鼠（BALB/c小鼠基因背景下引入C57BL/6小鼠Listr1遗传位点的同类系小鼠）和BALB/c小鼠,分析二者生存率和感染率的差异;HE染色分析P.y17XL感染后第5天C.B6By Listr1小鼠和BALB/c小鼠肝脏组织损伤情况;定量PCR法检测P.y17XL感染后小鼠肝脏组织第1、2、5天IL-1β、IL-6、TNF-α、IFN-γ的表达含量。结果显示,P.y17XL感染后4~8 d C.B6By Listr1小鼠虫血症水平显著高于BALB/c小鼠（P＜0.05）。C.B6By Listr1小鼠于感染后7~9 d全部死亡;而半数BALB/c小鼠于感染后8~9 d死亡,其余BALB/c小鼠至感染后第13天仍存活,两种小鼠生存率差异具有统计学意义（P＜0.01）。C.B6By Listr小鼠P.y17XL感染后第5天肝组织HE染色可见到明显的疟色素沉积;而BALB/c小鼠全片基本未见到疟色素的沉积。P.y17XL感染后第2天BALB/c小鼠肝组织IL-6（P＜0.05)、TNF-α（P＜0.05)mRNA水平显著高于C.B6By Listr1小鼠。结果表明Listr1遗传位点可以影响小鼠对疟原虫的易感性,与肝脏固有免疫相关。     

PD-1对伯氏疟原虫感染小鼠体液免疫应答的影响

利用伯氏疟原虫Plasmodium berghei ANKA(P.b ANKA)感染BALB/c小鼠,PD-1单抗阻断后,流式细胞术检测脾脏浆细胞、滤泡辅助性T细胞(Tfh)数量。qRT-PCR检测IL-21、IL-10和IL-6 mRNA水平,ELISA检测血清抗体,以探讨程序性死亡受体-1(programmed cell death-1, PD-1)在疟原虫初次感染中对体液免疫应答的影响。结果发现,PD-1单抗阻断加速了P.b ANKA感染小鼠的死亡。与对照组相比,PD-1阻断组感染后第12天短寿浆细胞(CD138~+CD44~+)数量明显降低(P0.05),长寿浆细胞(CD138~+CD44~-、CD138~-CD44~+)和Tfh(CD4~+CXCR5~+)细胞数量无差异性改变,脾细胞IL-21的mRNA水平明显下降(P0.05),血清抗裂殖子表面蛋白(merozoite surface protein, MSP)-1特异性IgG无明显改变。P.b ANKA感染中PD-1通路可能通过影响Tfh分泌IL-21进而干扰浆细胞数量影响体液免疫应答。     

Plasmodium falciparum: Differential merozoite dose requirements for maximal production of various inflammatory cytokines

The ligand specificity of TLRs and the details of signaling pathways that are activated by ligand–receptor engagements have been studied extensively. However, it is not known whether the signaling events initiated by defined doses of ligand are uniformly effective in producing various cytokines. In this study, we investigated the dose requirement for the saturated production of representative inflammatory cytokines, TNF-α, IL-6 and IL-12, by DCs stimulated with Plasmodium falciparum merozoites/protein–DNA complex or a CpG ODN TLR9 ligand. The data demonstrate that the ligand doses required for the maximal expression of TNF-α and IL-6 are substantially higher than those required for the maximal production of IL-12. The data also demonstrate that the uptake capacity of malaria parasite by plasmacytoid DCs is markedly lower than that of myeloid DCs, and that, like myeloid DCs, plasmacytoid DCs produce significant levels of TNF-α and IL-12 when the uptake of malarial DNA is facilitated by carrier molecules such as polylysine or cationic lipids. These results have implications for enhancing the effectiveness of vaccine against malaria by modulating the innate immune responses of plasmacytoid DCs to malaria parasites.     

Variant genes and the spleen in Plasmodium vivax malaria

It is generally accepted that Plasmodium vivax, the most widely distributed human malaria, does not cytoadhere in the deep capillaries of inner organs and thus this malaria parasite must have evolved splenic evasion mechanism in addition to sequestration. The spleen is a uniquely adapted lymphoid organ whose central function is the selective clearance of cell and other particles from the blood, and microbes including malaria. Splenomegaly is a hallmark of malaria and no other disease seems to exacerbate this organ as this disease does. Besides this major selective clearance function however, the spleen is also an erythropoietic organ which, under stress conditions, can be responsible for close to 40% of the RBC populations. Data obtained in experimental infections of human patients with P. vivax showed that anaemia is associated with acute and chronic infections and it has been postulated that the continued parasitemia might have been sufficient to infect and destroy most circulating reticulocytes. We review here the basis of our current knowledge of variant genes in P. vivax and the structure and function of the spleen during malaria. Based on this data, we propose that P. vivax specifically adhere to barrier cells in the human spleen allowing the parasite to escape spleen-clearance while favouring the release of merozoites in an environment where reticulocytes, the predominant, if not exclusive, host cell of P. vivax, are stored before their release into circulation to compensate for the anaemia associated with vivax malaria.     

夏氏疟原虫感染过程中调节性B细胞的表达变化

调节性B细胞(regulatory B cells,Bregs)是近年来发现的通过分泌IL-10发挥免疫调节作用的B细胞,其在疟疾免疫应答中的作用尚不清楚。利用血液阶段夏氏疟原虫(Plasmodium chabaudi AS,P.c AS)感染的BALB/c小鼠,观察了感染过程中Bregs数量变化及其表面分子表达情况。结果显示,BALB/c小鼠感染P.c AS后红细胞感染率逐渐升高,于感染后第9天达到30%,多数小鼠死亡。脾组织细胞因子IL-10 mRNA水平在感染后显著升高,感染后第5天达到高峰,感染后第8天仍为正常小鼠的10倍左右。CD4+细胞中IL-10+细胞百分比和绝对数量在感染后第5天达到峰值,于感染后第8天回落至正常水平;而CD19+细胞中IL-10+细胞(Bregs)百分比在感染后持续上升,在感染后第8天达到CD19+细胞的5%左右;感染后第5天,脾中CD4+IL-10+细胞绝对数量高于CD19+IL-10+细胞,至感染后第8天,CD19+IL-10+细胞绝对数量显著高于CD4+IL-10+细胞(P﹤0.01),约90%Bregs为CD5-细胞。结果提示,P.c AS感染过程中Bregs显著活化,是感染1周后IL-10的主要产生细胞。     

Relationship between in vivo synchronicity of Plasmodium falciparum and allelic diversity

Plasmodium falciparum cells tend to grow in synchronicity during their cyclic intraerythrocytic development in vivo. Both host and parasite factors appear to be involved in this synchronization. We examined the link between mixed-allelic-family P. falciparum infection and synchronicity in parasitized red blood cells (PRBC) from symptomatic children.The distribution of rings and trophozoites in each PRBC sample was determined by standard microscopy. P. falciparum was genotyped by using a polymerase chain reaction (PCR) targeting three loci (merozoite surface proteins (MSP) 1 and 2, and 175-kD erythrocyte binding antigen (EBA), allowing us to distinguish parasite clones belonging to a single-allelic family (SAF) and those belonging to a mixed-allelic family (MAF). Parasite development was considered synchronous when peripheral blood contained at least 95% of rings or 95% of trophozoites.Parasite development was synchronous in 22 (21.2%) of the 104 children studied. Twenty (90.9%) of these infections were SAF and two (9.1%) were MAF. Rings and trophozoites predominated in respectively 12 (60%) and 8 (40%) SAF infections. Respectively 17.1% and 82.9% of the 82 asynchronous cases corresponded to SAF and MAF infection. Parasite synchronicity was therefore significantly related to single-allelic-family infection (p < 2 × 10^− 10).Twenty different MSP-1 alleles and thirteen different MSP-2 alleles were identified. Only three isolates from patients with SAF infection comprised a single allele or genotype, the other isolates harboring at least two alleles. The mean number of alleles or clones was respectively 3.0 and 10.0 in SAF and MAF infection. These results reflect the allelic diversity of the MSP loci and show that SAF infection can correspond to multiple parasite clones (or genotypes) but, in general, fewer than in MAF infection (p ≤ 0.0007).These results confirm the extensive polymorphism of P. falciparum vaccine candidates MSP-1 and -2 in southeastern Gabon and demonstrate that parasite synchronicity in vivo is strongly associated with single-allelic-family infection.