Role of lipoteichoic acid in infection and inflammation

Lipoteichoic acid (LTA) is a surface-associated adhesion amphiphile from Gram-positive bacteria and regulator of autolytic wall enzymes (muramidases). It is released from the bacterial cells mainly after bacteriolysis induced by lysozyme, cationic peptides from leucocytes, or beta-lactam antibiotics. It binds to target cells either non-specifically, to membrane phospholipids, or specifically, to CD14 and to Toll-like receptors. LTA bound to targets can interact with circulating antibodies and activate the complement cascade to induce a passive immune kill phenomenon. It also triggers the release from neutrophils and macrophages of reactive oxygen and nitrogen species, acid hydrolases, highly cationic proteinases, bactericidal cationic peptides, growth factors, and cytotoxic cytokines, which may act in synergy to amplify cell damage. Thus, LTA shares with endotoxin (lipopolysaccharide) many of its pathogenetic properties. In animal studies, LTA has induced arthritis, nephritis, uveitis, encephalomyelitis, meningeal inflammation, and periodontal lesions, and also triggered cascades resulting in septic shock and multiorgan failure. Binding of LTA to targets can be inhibited by antibodies, phospholipids, and specific antibodies to CD14 and Toll, and in vitro its release can be inhibited by non-bacteriolytic antibiotics and by polysulphates such as heparin, which probably interfere with the activation of autolysis. From all this evidence, LTA can be considered a virulence factor that has an important role in infections and in postinfectious sequelae caused by Gram-positive bacteria. The future development of effective antibacteriolitic drugs and multidrug strategies to attenuate LTA-induced secretion of proinflammatory agonists is of great importance to combat septic shock and multiorgan failure caused by Gram-positive bacteria.     

A组乙型链球菌脂磷壁酸的提取及其交叉反应性研究

目的 探讨A组乙型链球菌(iAS)脂磷壁酸(LTA)提取方法及其在风湿热发病过程中的意义。方法 用曲通114(TX—114)从GAS中提取LTA并用阴离子交换树脂二乙基氨基纤维素(DEAE—Sephace1)层析纯化；做LTA与人心瓣膜抗原吸附试验；分析LTA抗体的滴度与风湿性心脏病瓣膜病理结果的关系。结果 用TX—114提取并用阴离子交换树脂DEAE-Sephaccl层析纯化的LTA纯度较高，且保持了LTA的生物学活性；吸附抗体后的血清标本LTA抗体由阳性转为阴性，而末吸附抗体的血清标本LTA抗体仍为阳性，提示LTA与人心瓣膜之间存在交叉抗原性：血清LTA—IgG抗体阳性的4例患者中有3例病理切片发现心瓣膜或心肌间质有灶性炎症细胞浸润；血清LTA-IgG抗体阴性的6例病人均未见灶性炎症细胞浸润(Fiher精确概率=0．033)。结论 TX—114法是提取GAS的LTA的有效新方法；GAS的UFA与人心瓣膜之间存在交叉抗原性，LTA可能参与了风湿热的发病过程。     

荧光标记A蛋白检测日本血吸虫特异性IgG抗体

本文报告用异硫氰酸荧光素(FITC)标记葡萄球菌A蛋白(FITC-SPA)检测日本血吸虫抗体,并用荧光标记的抗人IgG(FITC-IgG)作平行对照检测。经粪孵证实为阳性的110例血吸虫病人,FITC-SPA检出率为92.7％,FITC-IgG为94.6％;前者对135例健康人的假阳性为1.5％,后者为3.7％,两者在检出率上无显著性差异(P>0.05)。FITC-SPA染色本底清楚,非特异染色少,染色时间短,且制备容易,试剂较稳定,是一种值得推荐的多功能免疫诊断试剂。     

Antibody response to virus-encoded proteins after cytomegalovirus mononucleosis

We determined serial IgG antibody responses to cytomegalovirus (CMV)-encoded proteins in sera collected over a one-year interval from 14 subjects with CMV mononucleosis. Antigens from infected human fibroblasts included three components: cytoplasmic, nuclear, and high-speed pellet. Antibody was detected by radioimmunoprecipitation followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Twenty to 21 bands were observed with the cytoplasmic component, whereas 10 and 9, respectively, were seen with the nuclear and high-speed pellet antigens. The most intense reactions occurred with the higher-molecular-mass proteins (50-215 kDa) by using the cytoplasmic and high-speed antigens and with the more rapidly migrating proteins (less than 50 kDa) by using the nuclear antigen. The precipitin responses increased for three months or more after onset of symptoms with the nuclear and high-speed pellet antigens but peaked within one to two months with the cytoplasmic antigen.     

Antibody response to measles vaccination in Turkish children

Summary In recent years, there has been a remarkable increase in measles cases among preschool and secondary school children in Turkey, as in many other countries. The seroconversion and coverage rates of measles vaccine should therefore be evaluated in order to obtain data that could be used to determine the vaccination policy for Turkey. Measles immunity status was studied by an enzyme-linked immunosorbent (ELISA) test determining the anti-measles IgG antibody levels. Measles specific IgG antibodies were found to be positive in 77.88% of the entire study group of 800 children aged 11 months to 12 years, while 21.25% had negative sera. Seven (0.87%) subjects had borderline results. The results of this study indicate the need to administer a second dose of measles vaccine, preferably at 18 months of age concomitant with other vaccines. This vaccination policy, together with an increase in the extent of immunization coverage, may help to achieve the World Health Organization's (WHO) target of the complete eradication of measles.

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Antikörperantwort auf Masernimpfung bei türkischen Kindern

Zusammenfassung Masernfälle haben in den letzten Jahren bei Vorschul- und Schulkindern in der Türkei erheblich zugenommen. Diese Beobachtung wurde auch in anderen Ländern gemacht. Es ist daher nötig, Untersuchungen zur Serokonversion und Durchimpfung mit Masernimpfstoff durchzuführen, um Daten zu haben, die als Grundlage für die Impfstrategien in der Türkei verwendet werden können. Der Masern-Immunstatus wurde mittels enzymgebundenem Immunsorbent-Assay (ELISA) bestimmt. Die Messung der anti-Masern IgG-Antikörperspiegel ergab einen positiven Befund bei 77,88% der gesamten Gruppe von 800 Kindern im Alter von 11 Monaten bis 12 Jahren. 21,25% der Seren wurden als negativ beurteilt. Sieben Kinder (0,87%) hatten grenzwertige Ergebnisse. Die Daten der Studie sprechen dafür, vorzugsweise im Alter von 18 Monaten eine zweite Dosis Masernimpfstoff zu applizieren, wenn auch andere Impfungen erfolgen. Mit dieser Impfstrategie und einer besseren Durchimpfung könnte das Ziel der Weltgesundheitsorganisation (WHO), Masern völlig auszurotten, leichter erreicht werden.

     

Synthesis of glycerol phosphate lipoteichoic acid in Staphylococcus aureus

Lipoteichoic acid (LTA), a glycerol phosphate surface polymer, is a component of the envelope of Gram-positive bacteria. However, the molecular basis for its synthesis or function is not known. Here we report that Staphylococcus aureus LtaS synthesizes glycerol phosphate LTA. Construction of a mutant S. aureus strain with inducible ltaS expression revealed that LTA synthesis is required for bacterial growth and cell division. An ltaS homologue of Bacillus subtilis restored LTA synthesis and the growth of ltaS mutant staphylococci. Thus, LtaS inhibition can be used as a target to treat human infections caused by antibiotic-resistant S. aureus or other bacterial pathogens.     

A组β溶血性链球菌脂磷壁酸抗体在风湿热诊断中的意义

目的 探讨A组β溶血性链球菌（乙链菌）脂磷壁酸（LTA）抗体在风湿热诊断中的意义。方法 用从A组乙链菌中提取的LTA作为抗原，采用斑点酶联免疫吸附测定（ELISA）法检测血清中的LTA抗体。结果 ①风湿性心脏炎组LTA－IgG抗体滴度水平高于静止期风湿性心脏病组、病毒性心肌炎组、非湿性心脏瓣膜病组，其他关节炎组的滴度水平；②活动期风湿热患者LTA－IgG抗体阳性率（64％）高于对照组的阳性率；③风湿性心脏炎患者的LTA－IgG抗体阳性率与外周血淋巴细胞促凝血活性（PCA）、抗链球菌壁多糖抗体（ASP）、抗DNAse－B、血沉、C反应蛋白的阳性率相接近，高于抗链球菌溶血素O(ASO)的阳性率。结论 血清LTA抗体在判断风湿热和风湿性心脏病风湿活动有较高的敏感性和一定的特异性。     

Structure-based mechanism of lipoteichoic acid synthesis by Staphylococcus aureus LtaS

Staphylococcus aureus synthesizes polyglycerol-phosphate lipoteichoic acid (LTA) from phosphatidylglycerol. LtaS, a predicted membrane protein with 5 N-terminal transmembrane helices followed by a large extracellular part (eLtaS), is required for staphylococcal growth and LTA synthesis. Here, we report the first crystal structure of the eLtaS domain at 1.2-Å resolution and show that it assumes a sulfatase-like fold with an α/β core and a C-terminal part composed of 4 anti-parallel β-strands and a long α-helix. Overlaying eLtaS with sulfatase structures identified active site residues, which were confirmed by alanine substitution mutagenesis and in vivo enzyme function assays. The cocrystal structure with glycerol-phosphate and the coordination of a Mn²⁺ cation allowed us to propose a reaction mechanism, whereby the active site threonine of LtaS functions as nucleophile for phosphatidylglycerol hydrolysis and formation of a covalent threonine–glycerolphosphate intermediate. These results will aid in the development of LtaS-specific inhibitors for S. aureus and many other Gram-positive pathogens.     

Bifidobacterium lipoteichoic acid and false ELISA reactivity in aspergillus antigen detection

A major difficulty with the detection of circulating galactomannan, a cell-wall polysaccharide released by Aspergillus sp during growth, in the serodiagnosis of invasive aspergillosis is the occurrence of false-positive ELISA results, especially in neonates and infants. On the basis of molecule similarity, we postulate that a lipoteichoic acid of Bifidobacterium sp can act as epitope for the monoclonal antibody used in the ELISA. The neonatal gut is heavily colonised with Bifidobacterium sp and these bacteria or their lipoteichoic acid might cause ELISA reactivity with serum after translocation because of immaturity of the intestinal mucosa. If our hypothesis is correct, we might find a method to discriminate between false-positive and true-positive ELISA results and thereby prevent unnecessary pre-emptive treatment of patients.     

Protection against Staphylococcus aureus by antibody to the polyglycerolphosphate backbone of heterologous lipoteichoic acid

Type 1 lipoteichoic acid (LTA) is present in many clinically important gram-positive bacteria, including enterococci, streptococci, and staphylococci, and antibodies against LTA have been shown to opsonize nonencapsulated Enterococcus faecalis strains. In the present study, we show that antibodies against E. faecalis LTA also bind to type 1 LTA from other gram-positive species and opsonized Staphylocccus epidermidis and Staphylcoccus aureus strains as well as group B streptococci. Inhibition studies using teichoic acid oligomers indicated that cross-reactive opsonic antibodies bind to the teichoic acid backbone. Passive immunization with rabbit antibodies against E. faecalis LTA promoted the clearance of bacteremia by E. faecalis and S. epidermidis in mice. Furthermore, passive protection also reduced mortality in a murine S. aureus peritonitis model. The effectiveness of rabbit antibody against LTA suggests that this conserved bacterial structure could function as a single vaccine antigen that targets multiple gram-positive pathogens.     

The adherence of group a streptococci to oropharyngeal cells: The lipoteichoic acid adhesin and fibronectin receptor

Summary The attachment of group A streptococci to oropharyngeal epithelial cells is mediated by adhesive molecules (adhesins) on the surfaces of the micro-organisms that interact with receptor molecules on the epithelial cells. The evidence that the adhesin is composed of lipoteichoic acid (LTA) complexed with bacterial cell surface proteins is as follows: (a) Among the purified cell wall substances tested, only LTA was able to inhibit attachment; (b) treatment of streptococci with anti LTA but not with antibody against other surface substances blocks attachment; (c) LTA forms complexes with purified M protein, the most abundant protein on the surface of virulent streptococci; (d) the lipid moieties of LTA, which mediate attachment, remain free in the M protein-LTA complexes to interact with receptor analogues, such as serum albumin. The evidence that the receptor for the LTA mediated binding of streptococci resides in fibronectin molecules on oropharyngeal cells is as follows: (a) the addition to adhesion test mixtures of fibronection inhibits binding; (b) the number of streptococci capable of attaching is directly proportional to the amount of fibronectin present on epithelial cells; (c) purified fibronectin immobilized on latex beads agglutinates suspensions of streptococci; (d) radiolabeled fibronectin binds to group A streptococci; (e) both the agglutination of fibronectin-beads and the binding of fibronectin to streptococci is blocked by LTA, the streptococcal adhesin.

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Adhärenz von Streptokokken der Gruppe A an Zellen des Mund-Rachen-Raumes: Lipoteicholsäure-Adhäsin und Fibronectin-Rezeptor

Zusammenfassung Die Adhäsion von Streptokokken der Gruppe A an Epithelien des Mund-Rachen-Raumes wird durch Haftmoleküle (Adhäsine) an der Oberfläche der Mikroorganismen vermittelt, die mit Rezeptormolekülen auf den Epithelzellen in Interaktion treten. Folgende Fakten belegen, daß das Adhäsin aus Lipoteicholsäure (LTA) besteht, die mit den Proteinen der Zelloberfläche einen Komplex bildet: (a) von allen getesteten gereinigten Zellwandsubstanzen war nur LTA imstande, die Adhärenz zu hemmen; (b) die Adhärenz wird durch Behandlung der Streptokokken mit anti-LTA blockiert, jedoch nicht durch Behandlung mit Antikörpern gegen andere Oberflächensubstanzen; (c) LTA bildet Komplexe mit gereinigtem M Protein, das von allen Proteinen auf der Oberfläche virulenter Streptokokken am reichlichsten vorkommt; (d) im Komplex aus M Protein und LTA bleiben die Lipidgruppen, die die Adhäsion vermitteln, frei für die Interaktion mit Rezeptoranaloga wie Serumalbumin. Der Beweis dafür, daß der Rezeptor für die LTA-vermittelte Bindung von Streptokokken in den Fibronectin-Molekülen auf oropharyngealen Zellen sitzt, kann aus folgendem abgeleitet werden: (a) bei Zusatz von Fibronectin zu einem Adhäsions-Testgemisch wird die Adhäsion verhindert; (b) die Anzahl der adhäsionsfähigen Streptokokken ist der Menge Fibronectin auf den Epithelzellen direkt proportional; (c) auf Latexkügelchen immobilisiertes, gereinigtes Fibronectin agglutiniert Streptokokkensuspensionen; (d) radioaktiv markiertes Fibronectin bindet Streptokokken der Gruppe A; (e) LTA, das Streptokokken-Adhäsin, blokkiert sowohl die Agglutination von Fibronectin-Kügelchen als auch die Bindung von Fibronectin an Streptokokken.

     

Antibody response of mice to chemically induced tumors.

BALB/c mice immunized with syngeneic methylcholanthrene-induced fibrosarcomas did not have antibodies against the unique tumor-specific transplantation antigens, even though they were capable of rejecting a lethal dose of tumor cells. Endogenous murine leukemia virus antigens expressed by certain of the tumors did, however, elicit high titers of antibodies, accounting for serological crossreactions that occurred between those tumors.     

Antibody response to Campylobacter pylori in diverse ethnic groups

Antibody response to Campylobacter pylori was measured in ethnic groups of Vietnamese, El Salvadorean and Ethiopian origin. The results were compared with the previously reported antibody titres found in sera of culture positive and culture negative patients, patients suffering from duodenal ulcer, white Australian blood donors and Australian Aboriginals. While in Vietnamese the prevalence of serologically positive sera was found to be similar to the white Australian population, numbers of serologically positive sera in El Salvadorean and Ethiopian ethnic groups was found to be very high. The high incidence of serologically positive sera in the Ethiopians correlated with the reported high incidence of duodenal ulcer in this population.     

Antibody response to human immunodeficiency virus after primary infection

The antibody response to human immunodeficiency virus (HIV) after primary infection was monitored in eight homosexual men with the acute mononucleosis-like illness associated with seroconversion. Multiple sera from each subject, taken at frequent intervals after onset of acute illness, were tested for antibody to HIV by IgM and IgG immunofluorescent assays (IFAs), four commercial enzyme-linked immunosorbent assays (ELISAs), and Western immunoblot (WB). Antibody to HIV was detected first by IgM IFA (mean +/- SD, 5 +/- 3 days), followed by IgG IFA (11 +/- 3 days); the IgM antibody titer peaked at 24 +/- 17 days and disappeared by 81 +/- 27 days, whereas the IgG antibody titer peaked at 133 +/- 63 days and has not disappeared in any subject. Antibody to HIV was first detected by ELISA from 31 +/- 14 to 58 +/- 32 days, depending on the assay kit used. Antibody to p24 and gp41 was first detected by WB at 24 +/- 10 days, followed by antibody to p55 (40 +/- 20 days), p68 (57 +/- 19 days), and p34 (71 +/- 22 days).     

Antibody response to Staphylococcus saprophyticus in urinary tract infection

The serological response towards Staphylococcus saprophyticus in young women with symptomatic urinary tract infection was measured with an enzyme-linked immunosorbent assay (ELISA) and a direct agglutination (DA) test. In both assays a marked antibody response was found in 2 of 3 patients with acute pyelonephritis caused by S. saprophyticus. Patients with acute cystitis due to S. saprophyticus or Escherichia coli showed antibody titers comparable to those of healthy controls.     

双歧杆菌脂磷壁酸延缓细胞衰老的作用机制

目的 探讨双歧杆菌脂磷壁酸(Lipoteichoic acid,LTA)在延缓H2O2诱导细胞衰老中的作用.方法 H2O2诱导WI-38细胞衰老,β-半乳糖苷酶细胞化学染色计算衰老细胞百分率变化,RT-PCR和Western印迹检测衰老细胞p21、细胞周期蛋白E(cyclin E)和周期蛋白依赖性蛋白激酶2(CDK2)表达水平的变化.结果 双歧杆菌LTA处理后,β-半乳糖苷酶细胞化学染色阳性细胞百分率较衰老模型组降低(P＜0.01).与年轻对照组相比,衰老模型组细胞中p21的表达增高,cyclin E和CDK2表达降低,而双歧杆菌LTA能够逆转上述变化(P＜0.01).结论 双歧杆菌能延缓H2O2诱导的细胞衰老,机制可能与改变p21,cyclin E和CDK2表达水平有关.