中药防治肺孢子虫肺炎的研究进展

肺孢子虫肺炎是由肺孢子虫引起的主要寄生于肺脏的一种致命性肺炎,常见于肿瘤放化疗者、器官移植术者或长期应用激素,尤其是艾滋病患者等免疫功能低下人群。随着肺孢子虫肺炎发病机制的逐步阐明,我国部分中药用于该病的防治取得了较好的疗效,具有广阔的应用前景。本文对近年来几种主要的抗肺孢子虫肺炎中药在防治肺孢子虫肺炎中的研究进展进行了综述。     

卡氏肺孢子虫的分类、命名、体外培养及其动物模型的建立

以往所称的“卡氏肺孢子虫” (Pneumocystiscarinii,Pc)能感染包括人和实验动物在内的多种哺乳动物 ,免疫力低下的宿主感染后能引起致命的卡氏肺孢子虫肺炎 (Pneumocystiscariniipneumonia,PCP )或称肺孢子虫病(Pneumocystosis)。国际上已将原感染人体的卡氏肺孢子虫 (Pneumocystiscarinii)更名为Pneumocystisjeroveci,国内张瑞娟、朱淮民( 2 0 0 3)将其译为耶氏肺孢子虫 ,然尚未被广泛应用。其生物学分类也由原来动物界的原虫定为真菌界的真菌类。重新命名和跨界的分类归属具有重要意义 ,然而 ,国内有关“卡氏肺孢子虫”的报道 ,尚未启…     

mtLSU-巢式PCR检测实验大鼠卡氏肺孢子虫的实验研究

目的对mtLSU-巢式PCR方法检测大鼠卡氏肺孢子虫的应用价值以及基因序列进行评价。方法采用地塞米松免疫抑制法诱导大鼠感染肺孢子虫;实验组10只,对照组1只;诱导至第7周时收集实验组及对照组大鼠肺组织和支气管肺泡灌洗液（BALF）标本,采用mtLSU-巢式PCR方法对人源与鼠源肺孢子虫共有的基因进行扩增和序列测定,同时采用镜检法对实验组大鼠肺组织和肺泡灌洗液标本进行检测,评估两种方法的敏感性。结果采用mtLSU-巢式PCR方法对实验感染大鼠肺组织和BAL进行检测,卡氏肺孢子虫DNA阳性率分别为100%（10/10）、90%（9/10）。而GMS染色镜检法检测的阳性率分别为80%（8/10）、60%（6/10）。所测Wistar大鼠卡氏肺孢子虫mtLSU基因序列长度为155bp,与GenBank的大鼠源肺孢子虫（U20170）及人源肺孢子虫（DQ473446）同源性均为100%（154/154、155/155）。结论 mtLSU-巢式PCR方法应用于大鼠卡氏肺孢子虫检测敏感性高,特异性强;获得与人源耶氏肺孢子虫相同的Wistar大鼠卡氏肺孢子虫mtLSU的基因序列。     

人源肺孢子虫纯培养株的建立及基因鉴定

目的建立人源肺孢子虫（PneUmOCySaSj／rovec／，Pj）纯培养株。方法从肺孢子虫肺炎（PCP）患者的支气管肺泡灌洗液（BALF）中分离巧，用改良IMDM培养基做原代、传代和冻存复苏培养；以四胺银染色计数法观察虫体增殖情况；以线粒体rRNA大亚基特异引物扩增培养物中的目的基因，与基因库中的鼠源和人源肺孢子虫基因做序列比较。结果用添加S-腺苷甲硫氨酸（SAM）等辅助剂的IMDM培养基从2例PCP患者的BALF中分离出2个巧纯培养株。分离培养的巧可进行冷冻保存和复苏培养。培养120h的巧包囊可增殖3．2倍。基因序列分析证实分离出的巧株与鼠源性肺孢子虫的线粒体rRNA大亚基同源性为67．8％，与GenBank中巧的同源性为93．2％。结论用本法建立了2个Pj纯培养株。     

复方磺胺甲恶唑对肾移植后卡氏肺孢子虫肺炎的预防作用

背景：卡氏肺孢子虫肺炎是由卡氏肺孢子虫寄生于肺部引起的一种严重的致命性肺炎。复方磺胺甲恶唑是目前用于治疗卡氏肺孢子虫肺炎的一线药物,治疗量往往有明显的不良反应,小剂量预防用药临床疗效及毒副作用尚不清楚。 目的：观察复方磺胺甲恶唑对肾移植后卡氏肺孢子虫肺炎的预防效果。 方法：选择肾移植后1个月且无复方磺胺甲恶唑过敏者。肾移植后1个月至半年或1年常规服用复方磺胺甲恶唑(0.48 g/d)。观察移植肝肾功能,感染情况,药物不良反应。 结果与结论：2006年起,随访125例肾移植术后早期患者,73例术后1个月起常规服用复方磺胺甲恶唑(0.48 g/d)至术后半年者,1例停药4个月后感染卡氏肺孢子虫肺炎死亡,47例服用复方磺胺甲恶唑(0.48 g/d)至术后1年者,无感染卡氏肺孢子虫肺炎者,5例因复方磺胺甲恶唑过敏或医从性差未服用复方磺胺甲恶唑者,2例分别在术后4,5个月感染卡氏肺孢子虫肺炎,1例死亡。结果提示,肾移植术后1个月至1年常规服用复方磺胺甲恶唑(0.48 g/d),可有效预防卡氏肺孢子虫肺炎,临床无明显不良反应。     

双氢青蒿素对卜氏肺孢子虫肺炎大鼠TNF—α水平的影响

目的 研究双氢青蒿素对卡氏肺孢子虫肺炎大鼠血清和肺泡巨噬细胞培养上清液TNF－α水平的影响。方法 以醋酸可的松皮下注射Wistar大鼠建立卡氏肺孢子虫肺炎动物模型，用60mg/kg双氢青蒿素治疗实验大鼠，杀鼠取肺，用胶原酶消化法分离肺泡巨噬细胞，用LPS刺培养72h，同时设有感染组和正常对照，用TNF－α水平则低于感染组。结论 卡氏肺孢子虫感染引起大鼠肺泡巨噬细胞分泌高水平的TNF－α，但双氢青蒿素治疗后PCP大鼠肺泡巨噬细胞产生TNF－α水平降低。     

寡核苷酸探针RNA原位杂交法检测肺孢子虫的研究

目的探讨RNA原位杂交法在肺孢子虫病理检测中的应用。方法采用小亚单位RNA位点来源的寡核苷酸探针、地高辛加尾标记、Wistar雌性大鼠皮下注射地塞米松建立肺孢子虫肺炎动物模型,取肺组织制备石蜡标本进行RNA原位杂交,并将结果与瑞氏-吉姆萨染色法进行比较。结果 RNA原位杂交法于感染后第3周检到虫体,呈游离分布;7～8周时检测到大量包囊;9～10周时滋养体大量出现;组织内肺孢子虫的检出率（32/32）高于瑞氏-吉姆萨染色法（25/32）。结论 RNA原位杂交法是一种敏感特异的肺孢子虫病理检测方法。     

两株人源隐孢子虫分离株的鉴定和种系发育分析

从郑州市某医院腹泻婴幼儿粪便中分离获得2个隐孢子虫分离株,应用巢式PCR扩增分离株SSU rRNA(18S rRNA)基因的特定片段,扩增产物分别用限制性内切酶SspⅠ和VspⅠ单酶切进行限制性片段多态性(RFLP)分析确定分离株种类或基因型.同时对扩增产物进行克隆和测序,并与GeBank上发表的相关参考序列进行同源性比较和种系发育分析.根据RFLP分析,2个分离株可初步确定为人隐孢子虫(Cryptosporidium hominis);种系发育分析表明2个分离株与C.hominis协的相应序列位于同一进化枝,序列同源性为100%.因此,本试验中获得的2个分离株应为C.hominis.     

加味补中益气汤治疗大鼠肺孢子虫肺炎的疗效观察

目的探讨加味补中益气汤治疗大鼠肺孢子虫肺炎（PCP）的疗效。方法按国内公认的PCP造模方法，建立大鼠PCP动物模型。设中药治疗组和预防组，同时建立西药对照组、PCP模型对照组及正常对照组。通过观察各组大鼠存活率、体重、肺内肺孢子虫包囊的数量和肺组织病理学变化考核药物疗效。结果中药组大鼠存活率高于PCP模型组，但低于正常组；中药治疗组和预防组大鼠平均体重高于PCP模型组，包囊数低于PCP模型对照组；中药治疗组和预防组大鼠肺组织炎症反应明显轻于PCP模型对照组。结论加味补中益气汤对大鼠肺孢子虫肺炎，有一定的疗效。     

肾移植后并发卡氏肺孢子虫肺炎36例资料回顾(英文)

背景:卡氏肺孢子虫肺炎是常见的肾移植后早期并发症,起病隐匿,进展快,若诊治不及时,死亡率高,认识和掌握肾移植后卡氏肺孢子虫肺炎的发生发展规律和干预措施具有重要的临床意义。目的:回顾性分析肾移植后并发卡氏肺孢子虫肺炎的病因、临床特点、诊疗措施及预后。方法:回顾分析36例南方医科大学珠江医院器官移植科收治的肾移植后并发卡氏肺孢子虫肺炎患者的临床资料,分析一般状况、临床表现、治疗方案及人、肾预后情况,总结和认识该病诊断干预措施。结果与结论:36例患者中男22例,女14例,33例痊愈且移植肾功能保持良好,3例患者并发严重急性呼吸窘迫综合征死亡。36例患者卡氏肺孢子虫肺炎发生在肾移植后6个月内31例,7～18个月5例。15例(41.7%)通过纤维支气管镜下支气管灌洗液或肺组织活检检出卡氏肺孢子虫,21例未检出。多数患者经过减少免疫抑制剂、给予复方磺胺甲恶唑及支持治疗后痊愈且移植肾功能良好。提示卡氏肺孢子虫肺炎多发生在肾移植后6个月内,临床症状典型,病原体难以发现,早期诊断主要依据临床病史、症状和影像学检查,尽早、足量给予复方磺胺甲恶唑,减少免疫抑制剂,充分的支持治疗能改善预后。     

Exploring transplacental transmission of Pneumocystis oryctolagi in first-time pregnant and multiparous rabbit does.

Pneumocystis sp. is transmitted through the airborne route and presents a high host-species-specificity. Occasional reports of Pneumocystis pneumonia in still births and newborn infants suggest that other routes of transmission, e.g. transplacental might occur. The latter has been reported in rabbits but available data indicate that transplacental transmission of Pneumocystis seems not to occur in corticosteroid-treated rats and in SCID mice. The present study was undertaken to evaluate transplacental transmission of Pneumocystis oryctolagi. The spontaneously-acquired pneumocystosis rabbit model using hybrid California/New Zealand white female rabbits was selected because of similarities among rabbit and human placentas. Three different experiments were conducted in France and Chile. Pneumocystis organisms were detected by microscopy in the lungs of pregnant does and Pneumocystis DNA was found in the lungs of fetuses from the multiparous does from the second week to the end of gestation. Pneumocystis DNA was not detected in fetuses from primiparous does. Detection of Pneumocystis oryctolagi--DNA in fetuses of multiparous does and not in those of primiparous ones, suggests that transplacental transmission may be favored by multiple gestations. Whether Pneumocystis-DNA in fetal tissues from multiparous does resulted from transplacental passage of viable transmissible forms requires further investigation.     

Genetic divergence at the SODA locus of six different formae speciales of Pneumocystis carinii.

Genetic divergence at the SODA (manganese-dependent superoxide dismutase, MnSOD) locus were compared in six Pneumocystis carinii formae speciales isolated from mouse, rabbit, human, macaque and pig. A degenerate oligonucleotide primer strategy was designed to amplify 85-90% of the full-length SODA gene from P. carinii genomic DNA isolates. DNA sequence analysis revealed an A/T bias in the nucleotide composition (71-77.2%) and the presence of seven small introns (41-142 bp), interrupting each P. carinii open reading frame (ORF) at the same position. The MnSOD deduced amino acid sequences from all P. carinii isolates shared residues which were conserved within the MnSOD family and which are required for enzymatic activity and binding of the cofactor metal. Phylogenetic analysis including MnSOD sequences from representatives of the fungal phyla Basidiomycota and Ascomycota indicated that the P. carinii formae speciales form a monophyletic group that is related to the budding yeasts (subphylum Saccharomycotina, previously called class Hemiascomycetes) in the Ascomycota. In the whole Pneumocystis group, P. carinii f. sp. hominis, P. carinii f. sp. macacae and P. carinii f. sp. oryctolagi MnSOD sequences clustered together, as did the rat-derived P. carinii and P. carinii f. sp. muris sequences.     

Pneumocystis

Pneumocystis organisms can cause pneumonia in mammals that lack a strong immune defense. The genus Pneumocystis contains many different organisms that can be distinguished by DNA sequence analysis. These different organisms are different species of yeast-like fungi that are most closely related to the ascomycete, Schizosaccharomyces pombe. Each species of Pneumocystis appears to be specific for the mammal in which it is found. The species that infects humans is Pneumocystis jiroveci. P. jiroveci has not been found in any other mammal and the species of Pneumocystis found in other mammals have not been seen in humans. Genetic variation among P. jiroveci samples is common, suggesting that there are many strains. Strain analysis shows that adults can be infected by more than one strain, and suggests that pneumonia can be the result of infection occurring proximal to the time of disease, rather than to reactivation of dormant organisms acquired in early childhood. Nevertheless, long-term colonisation may be occurring. A large fraction of normal children and animals show evidence of infection. A Pneumocystis species that grows in rats has been shown to possess a complex genetic system for surface antigen variation, a strategy employed by other microbes that dwell in immunocompetent hosts. These findings, together with strong host specificity, suggest that Pneumocystis species may be obligate parasites. The source of infection is not clear. Pneumocystis DNA is detectable in the air, but is scarce except in environments occupied by individuals with Pneumocystis pneumonia. In a few cases, there is direct evidence of person to person transmission. In general, however, patients and their contacts have been found to have different strains of P. jiroveci.     

A novel diagnostic method of Pneumocystis carinii. In situ hybridization of ribosomal ribonucleic acid with biotinylated oligonucleotide probes

The reactivity and specificity of the in situ hybridization of ribosomal RNA in the diagnosis of Pneumocystis carinii were investigated. Three complementary oligonucleotide probes, 22 and 25 nucleotides long, corresponding to the species specific regions of 5S and 18S ribosomal RNA of Pneumocystis carinii were synthesized and labeled with biotinylated dUPT at the 3' termini. In situ hybridization was performed on formalin-fixed paraffin-embedded human lung tissues using the mixture of these probes and detected with the avidin-biotin peroxidase complex method. The reactions were positive in all 12 cases of Pneumocystis carinii pneumonia, but in none of the infections with other pathogenic agents, including virus (6 cases), mycobacteria (4 cases), protozoa (4 cases) and fungi (8 cases). The reactivity and specificity of this method was comparable with that of immunohistochemistry using a monoclonal anti-human Pneumocystis carinii antibody. Because the specificity of in situ hybridization is based on nucleotide sequences of ribosomal RNAs, that are constant among species, contrary to morphology of protista or expression of antigens, it should complement conventional staining and immunohistochemical methods, and provide a useful tool for the diagnosis of Pneumocystis carinii.     

Pneumocystis carinii: an update

Pneumocystis produces respiratory infection in immunocompromised individuals of several species of mammals, including humans. Each mammalian species has its own specific Pneumocystis species, which does not cross-infect other mammals. The species infecting humans has now been renamed P. jerovici , since P. carinii is reserved for one of two species infecting rats. Long believed to be a protozoan, Pneumocystis is now classified as an Archiascomycetous fungus. This is based on new molecular taxonomic techniques using DNA sequence analysis of srRNA genes. Only two of about 140 copies of the gene that exist in Pneumocystis were used for sequencing, so the evidence is not conclusive; however, it is supported by morphological evidence such as fungus-specific nucleus-associated organelles for cell division. There is also ultrastructural evidence of meiotic division and sexual conjugation. Clinically, several lines of evidence suggest the improbability of latent infection. Adult infections appear to be new infections, a fact that invites a new perspective on prevention.     

Immunity against the opportunistic fungal pathogen Pneumocystis.

Species of the genus Pneumocystis exist as opportunistic fungal pathogens and are associated with severe pneumonia and pulmonary complications in immunocompromised individuals. Although prophylactic therapy for Pneumocystis has significantly decreased the overall incidence of infection, more than 80% of cases in current patient populations are considered breakthrough cases. In the HIV-infected population, in the years following the initiation of highly active antiretroviral therapy (HAART), significant reductions in the incidence of Pneumocystis infection were observed, although trends over the last several years suggest that the incidence of Pneumocystis has plateaued rather than decreased. Furthermore, with the more prominent usage of immunosuppressive therapies, the frequency of Pneumocystis infection in the HIV-negative population, such as those with hematologic malignancies and those who have undergone transplantation, has risen significantly. Investigating host defense mechanisms against P. carinii has historically been problematic due to the difficulty in achieving continuous in vitro propagation of proliferating Pneumocytis organisms. Nevertheless, clinical and experimental studies have documented that host defense against Pneumocystis involves a concerted effort between innate, cell-mediated (T lymphocyte) and humoral (B lymphocyte) responses. However, the pulmonary environment is a tissue site where heightened inflammatory responses can often lead to inflammation-mediated injury, thereby contributing to the pathogenesis of Pneumocystis infection. Accordingly, clearance of Pneumocystis from the pulmonary environment is dependent on a delicate equilibrium between the inflammatory response and immune-mediated clearance of the organism. Furthermore, innate and adaptive responses against Pneumocystis are strikingly similar to those against other medically-important fungi, thus providing additional evidence that Pneumocystis exists as a fungal organism.     

A single-copy gene encodes Kex1, a serine endoprotease of Pneumocystis jiroveci

We have cloned and characterized the kex1 gene of Pneumocystis jiroveci. Unlike the case for Pneumocystis carinii, in which the homologous PRT-1 genes are multicopy, kex1 is a single-copy gene encoding a protein homologous to fungal serine endoproteases, which localize to the Golgi apparatus. Thus, substantial biological differences can be seen among Pneumocystis species.     

Monoclonal antibody to Pneumocystis carinii. Comparison with silver stain in bronchial lavage specimens.

Monoclonal 3F6 anti-Pneumocystis carinii antibody (MAB-3F6) was used to stain cell blocks from 164 bronchial lavage specimens from patients with the acquired immune deficiency syndrome (AIDS) and AIDS-related complex and compared with slides stained with Grocott's modification of the Gomori methenamine silver stain. Pneumocystis organisms were present in 83 of 164 cases using MAB-3F6 stain, whereas Grocott's modified silver stain demonstrated Pneumocystis organisms in 48. MAB-3F6 demonstrated Pneumocystis organisms in 38 cases with negative silver stains, whereas silver stain identified Pneumocystis organisms in only three MAB-3F6-negative cases. Of 70 patients with clinical Pneumocystis pneumonia at the time of the specimen was obtained, 59 had MAB-3F6-positive specimens, whereas 39 had organisms detected using Grocott's modified silver stain. Of 37 patients without clinically apparent Pneumocystis pneumonia any time in their course, 4 had abundant organisms and 33 had negative stains with MAB-3F6. MAB-3F6 detected Pneumocystis organisms in 22 of 31 cases of Pneumocystis pneumonia that had no organisms identified using Grocott's silver stain (X2 = 5.76, P = 0.016). MAB-3F6 immunochemical staining is a more sensitive method than Grocott's modified silver stain to detect Pneumocystis organisms.     

The biology of Pneumocystis carinii

Some basic biologic aspects of Pneumocystis are reviewed. From the available data, it is evident that only two stages, the trophozoite and the cyst, have been described, but that the complete life cycle is unknown. Both of these two stages are found in the alveoli and other tissues of hosts with some forms of immune suppression, but rarely in healthy ones. The current views of how trophozoites evolve into cysts is outlined. No agreement about the classification of Pneumocystis has been reached, and its protozoan or fungal nature has not been fully confirmed. Recent data obtained with electron microscopy, and biochemical and molecular biologic studies, indicate that Pneumocystis has characteristics more akin to a fungus than to a protozoan. Moreover, the existence of one or of several species of Pneumocystis has not been determined. The mode of transmission of the parasite in nature, between different hosts, remains unconfirmed, although the cyst is believed to play a role.