Chlamydial Lipopolysaccharide Research Articles

Immunohistochemical staining of chlamydial antigen in emerald tree boas (Corallus caninus).

Of 120 privately owned captive-bred and wild-collected emerald tree boas (ETBs) (Corallus caninus), 97 died or were euthanatized. Eighteen snakes were necropsied, and tissues were collected from all major organs and processed for light microscopy. Histologic examination demonstrated histiocytic granulomas in the small intestine, heart, and esophageal tonsils of one ETB, small intestine of a second ETB, and in an esophageal tonsil of a third ETB. Within the center of these granulomas, small, basophilic, punctate organisms were demonstrated using hematoxylin and eosin staining. Transmission electron microscopic examination of an intestinal granuloma demonstrated developmental stages of organisms consistent with members of the family Chlamydiaceae. An immunoperoxidase staining technique and 2 different commercially available monoclonal antibodies against chlamydial lipopolysaccharide antigen was used to identify chlamydial antigen in these lesions. Liver of a puff adder (Bitis arietans) with previously reported systemic chlamydiosis served as the positive control. Both monoclonal antibodies stained antigen in these granulomas. Additionally, macrophages within aggregates of lymphoplasmacytic cells in the colon, small intestine, and esophageal tonsils of 3 other ETBs contained antigen. Although both antibodies labeled antigen in serial sections of tissue, a difference in staining intensity was noted.

Effects of azithromycin and rifampin on Chlamydia trachomatis infection in vitro.

An in vitro cell culture model was used to investigate the long-term effects of azithromycin, rifampin, and the combination of azithromycin and rifampin on Chlamydia trachomatis infection. Although standard in vitro susceptibility testing indicated efficient inhibition by azithromycin, prolonged treatment did not reveal a clear elimination of chlamydia from host cells. Chlamydia were temporarily arrested in a persistent state, characterized by culture-negative, but viable, metabolically active chlamydia, as demonstrated by the presence of short-lived rRNA transcripts. Additionally, azithromycin induced generation of aberrant inclusions and an altered steady-state level of chlamydial antigens, with the predominance of Hsp60 protein compared to the level of the major outer membrane protein. Treatment with azithromycin finally resulted in suppression of rRNA synthesis. Chlamydial lipopolysaccharide and processed, functional rRNA were detectable throughout the entire incubation period. These in vitro data show a good correlation to those from some recent clinical investigations that have reported on the persistence of chlamydia, despite appropriate antibiotic treatment with azithromycin. Rifampin was highly active by in vitro susceptibility testing, but prolonged exposure to rifampin alone for up to 20 days resulted in the emergence of resistance. No development of resistance to rifampin was observed when chlamydia-infected cells were incubated with a combination of azithromycin and rifampin. This combination was shown to be more efficient than azithromycin alone, in that suppression of rRNA synthesis occurred earlier. Thus, such a combination may prove more useful than azithromycin alone.

Cross-reaction between the genus-specific lipopolysaccharide antigen of Chlamydia spp. and the lipopolysaccharides of Porphyromonasgingivalis,Escherichia coli O119 and Salmonellanewington: Implications for diagnosis

Seven hybridoma clones, secreting monoclonal antibodies (MAbs) against the genus-specific chlamydial lipopolysaccharide (LPS) antigen were obtained after immunization of BALB/c mice with formalin killed Chlamydia psittaci. The antigen-binding properties of the MAbs were characterized in different immunologic reactions with purified chlamydial elementary bodies and LPS antigens from S- and R-forms of Gram-negative bacteria. Four MAbs reacted with the heterologous LPS antigens of Salmonella R-mutants, Escherichia coli Re chemotype and Acinetobacter calcoaceticus. Two MAbs demonstrated in addition a significant reactivity with Porphyromonas gingivalis, E. coli O119 and Salmonella newington LPS in ELISA, dot-ELISA and passive hemolysis assay (for clone 204G9). One MAb cross-reacted only with Salmonella minnesota Re LPS in ELISA. In indirect immunofluorescent assay six MAbs produced bright green fluorescence with all tested chlamydial strains and five of them reacted with the Re and Rb2 chemotypes of S. minnesota. The results demonstrate a wide cross-reactivity of the produced MAbs with LPS antigens of various Gram-negative bacteria, posing the question for careful consideration and interpretation of serology results for Chlamydia spp.

Structural analyses of the lipopolysaccharides from Chlamydophila psittaci strain 6BC and Chlamydophila pneumoniae strain Kajaani 6

Lipopolysaccharides (LPSs) of Chlamydophila psittaci 6BC and Chlamydophila pneumoniae Kajaani 6 contain 3-deoxy- d- manno-oct-2-ulosonic acid (Kdo), GlcN, organic bound phosphate, and fatty acids in the molar ratios of ∼3:2:2.2:4.8 and ∼2.9:2:2.1:4.9, respectively. The LPSs were immunoreactive with a monoclonal antibody against a family-specific epitope of chlamydial LPS. This finding, together with methylation analyses of both LPSs and MALDI-TOF MS experiments on de- O-, and de- O, N-acylated LPSs, indicate the presence of a Kdo trisaccharide proximal to lipid A having a structure α-Kdo-(2→8)-α-Kdo-(2→4)-α-Kdo, which appears to be the main component of the core region in the native chlamydial LPSs. In the de- O-acylated LPSs from Chl. psittaci 6BC and Chl. pneumoniae Kajaani 6, two major molecular species are present that differ in distribution of amide-bound hydroxy fatty acids over both GlcN. It appears that either two ( R)-3-hydroxy-18-methylicosanoic acids or one ( R)-3-hydroxy-18-methylicosanoic acid and one ( R)-3-hydroxyicosanoic acid are attached to the GlcN residues. In contrast, the de- O-acylated LPS of Chl. psittaci PK 5082 contains one major molecular species that has two ( R)-3-hydroxyicosanoic acid residues attached to two GlcN residues.

HLA-B27 expression does not modulate intracellular Chlamydia trachomatis infection of cell lines.

Chlamydia trachomatis is an obligate intracellular pathogen. Infection of susceptible individuals with this bacterium can trigger the development of reactive arthritis, an acute inflammation that is associated with the expression of the class I major histocompatibility antigen, HLA-B27. Other facultative intracellular pathogens, such as Yersinia and Salmonella spp., are also known triggers of reactive arthritis. Previous studies report conflicting results concerning whether the presence of HLA-B27 modulates the infection of cells with these enteric pathogens. In the present study, we have examined whether the expression of HLA-B27 can influence the infection of cell lines with C. trachomatis and also whether the replication of these bacteria is altered in HLA-B27-expressing cell lines. To do this, we have used a sensitive flow cytometric approach. We fixed and permeabilized cells and used fluorescein isothiocyanate-conjugated monoclonal antibody specific for chlamydia lipopolysaccharide to detect intracellular bacteria. The staining pattern obtained closely resembled the intracellular life cycle of chlamydia, with the appearance of brightly staining cells correlating to the microscopic detection of mature inclusion bodies. Moreover, since the percentage of cells that stained with the antibody was proportional to the infectious inoculum used, we were able to use the technique to quantitate the number of infectious organisms recoverable from infected cell lines. An important component of our study was the use of heparin to prevent reinfection of cells and thus enable the infection to be followed from a discrete time point. Our results suggest that HLA-B27 influences neither the infection nor replication of C. trachomatis serovar L2 within cell lines. Consequently, the role of HLA-B27 in the pathogenesis of reactive arthritis may lie downstream of the invasion and replication stages of the triggering pathogenic infection.

Chlamydia pneumoniae-infected monocytes exhibit increased adherence to human aortic endothelial cells

Interactions between monocytes and endothelial cells play an important role in the pathogenesis of atherosclerosis, and monocyte adhesion to arterial endothelium is one of the earliest events in atherogenesis. Work presented in this study examined human monocyte adherence to primary human aortic endothelial cells following monocyte infection with Chlamydia pneumoniae, an intracellular pathogen associated with atherosclerosis by a variety of sero-epidemiological, pathological and functional studies. Infected monocytes exhibited enhanced adhesion to aortic endothelial cells in a time- and dose-dependent manner. Pre-treatment of C. pneumoniae with heat did not effect the organism’s capacity to enhance monocyte adhesion, suggesting that heat-stable chlamydial antigens such as chlamydial lipopolysaccharide (cLPS) mediated monocyte adherence. Indeed, treatment of monocytes with cLPS was sufficient to increase monocyte adherence to endothelial cells, and increased adherence of infected or cLPS-treated monocytes could be inhibited by the LPS antagonist lipid X. Moreover, C. pneumoniae-induced adherence could be inhibited by incubating monocytes with a mAb specific to the human β2-integrin chain, suggesting that enhanced adherence resulted from increased expression of these adhesion molecules. These data show that C. pneumoniae can enhance the capacity of monocytes to adhere to primary human aortic endothelial cells. The enhanced adherence exhibited by infected monocytes may increase monocyte residence time in vascular sites with reduced wall shear stress and promote entry of infected cells into lesion-prone locations.

Antibodies to chlamydial lipopolysaccharides in unstable angina pectoris

Patients with coronary artery disease frequently have elevated antibody titers against Chlamydia pneumoniae, but whether antichlamydial antibody titers are correlated with prognosis in unstable angina remains unclear. We therefore investigated the sera of 1,096 patients with unstable angina regarding immunoglobulin (Ig) IgG, IgA, and IgM antibody titers against chlamydial lipopolysaccharides (LPS) and the concentrations of C-reactive protein (CRP) and troponin T (TnT). Anti-LPS IgG titers were increased in 45% of patients at enrollment and in 48% of patients at discharge (p <0.0001). Anti-LPS IgA titers were increased in 27% of patients at enrollment and in 33% of patients at discharge (p <0.0001). Patients who subsequently died had significantly lower IgM titers at enrollment than patients without events (p = 0.016). IgG, IgA, or IgM titers did not correlate with concentrations of CRP or TnT. In this large-scale study of patients with unstable angina, we frequently found elevated antichlamydial antibody titers. Patients with low IgM anti-LPS titers were at risk for subsequent death. However, there was no correlation between antichlamydial antibody titers and CRP or TnT.

Does infection with chlamydia pneumoniae and/or helicobacter pylori increase the expression of endothelial cell adhesion molecules in humans?

Abstract Objective To investigate if Chlamydia pneumoniae and/or Helicobacter pylori seropositivity is associated with elevated levels of soluble endothelial cell adhesion molecules (sCAMs) as markers of atherosclerotic activity. Methods Immunoglobulin A (IgA) and IgG antibodies to the two bacteria, soluble intercellular cell adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1 (sVCAM-1) and E-selectin were measured in coronary heart disease (CHD) patients ( n = 193) and age- and sex-matched controls ( n = 193). Two different serological methods were used for the detection of Chlamydia antibodies: Labsystems microimmunofluorescence to detect species-specific C. pneumoniae antibodies and Medac's recombinant enzyme-linked immunosorbent assay to detect genus-specific lipopolysaccharide antibodies. Results The concentrations of sICAM-1 and E-selectin were higher in CHD patients with positive vs. negative Chlamydia lipopolysaccharide IgA ( P = 0.044 for both). H. pylori antibodies alone did not predict raised levels of sCAMs, but in CHD patients sICAM-1 was increased with IgA seropositivity to both bacteria compared to double seronegativity ( P = 0.034). Concentrations of sVCAM-1 were elevated in CHD patients with double IgA seropositivity compared to those with Chlamydia lipopolysaccharide IgA seropositivity alone ( P = 0.018). Conclusion Our results may indicate that C. pneumoniae contributes to increased inflammation in CHD, and that this contribution is even more pronounced when present in combination with H. pylori IgA antibodies.

Current infection with Helicobacter pylori, but not seropositivity to Chlamydia pneumoniae or cytomegalovirus, is associated with an atherogenic, modified lipid profile.

Infectious agents may be involved in atherothrombogenesis. The potential pathogenic pathway, however, remains unclear. We investigated the association between various infectious agents and lipoproteins known to have an atherogenic effect. We recruited 470 healthy blood donors and 238 patients with angiographically proven coronary heart disease (CHD), aged 40 to 68 years. Seropositivity to Chlamydia pneumoniae (CP), chlamydial lipopolysaccharide, and cytomegalovirus (CMV) was determined; infection with Helicobacter pylori (HP) was assessed by using the [(13)C]urea breath test. In all subjects, total cholesterol, high density lipoprotein (HDL) cholesterol, lipoprotein(a), and various apolipoproteins (apos) were determined. In unadjusted analysis, mean HDL cholesterol concentration was significantly decreased in HP-positive healthy subjects (1.36 vs 1.44 mmol/L, P=0.006) compared with HP-negative subjects. The HDL cholesterol to total cholesterol ratio was significantly decreased in HP-positive (0.259 vs 0.276, P=0.01) and CP-seropositive (0.266 vs 0.280, P=0.04) healthy subjects compared with (sero)negatives. Mean apoAI levels were significantly lower in HP-positive healthy subjects (1.46 vs 1.51 g/L, P=0.03) and in CMV-positive healthy subjects (1.47 vs 1.52 g/L, P=0.01) compared with (sero)negative subjects. After multivariable adjustment by means of linear regression analysis, only the association between HP infection and decreased HDL cholesterol (P=0.002), decreased HDL cholesterol to total cholesterol ratio (P:=0.005), decreased apoAI (P=0.02), and increased apoB (P=0.02) persisted and remained significant. There was no independent association between other lipoproteins and serological markers of CP or CMV infection. Current infection with HP, but not seropositivity to CP or CMV, was associated with an atherogenic, modified lipid profile. These lipid alterations could explain, at least in part, the reported weak association between chronic HP infection and atherosclerotic diseases.

Detection of chlamydial antibody by fetal serology--an aid to the diagnosis of ovine abortion.

Two serological tests (indirect immunofluorescence and enzyme-linked immunosorbent assay) were developed for the detection of fetal antibody to Chlamydia psittaci. Fetal blood and thoracic fluid from 126 field cases of suspected ovine chlamydial abortion were examined using both tests. Placenta and fetal tissues (lung, liver, and kidney) from the same animals were also examined by the following conventional diagnostic methods: isolation in McCoy cells, detection of chlamydial lipopolysaccharide (LPS), modified Ziehl-Nielsen staining, and direct fluorescent antibody staining of chlamydia in frozen cryostat sections. Seventy cases were positive by fetal serology, and of these, 68 were also positive by isolation and/or LPS detection. The remaining 56 cases had negative fetal serology, and of these, 39 were positive by isolation and/or LPS detection. Results indicate that fetal serology, although less sensitive than either isolation in McCoy cells or detection of chlamydial LPS antigen, may be of particular use when placenta is not available.

A monoclonal antibody recognizing the 3-deoxy-D-manno-oct-2-ulosonic acid (Kdo) trisaccharide αKdo(2→4)αKdo(2→4)αKdo of Chlamydophila spacepsittaci 6BC lipopolysaccharide

A monoclonal antibody (mAb) S45-18 was generated against a synthetic neoglycoconjugate containing the trisaccharide alphaKdo(2-->4)alphaKdo(2-->4)alphaKdo (Kdo, 3-deoxy-D-manno-oct-2-ulopyranosonic acid) which represents a structure of the lipopolysaccharide (LPS) from Chlamydophila psittaci 6BC. The antibody was characterized by binding and inhibition assays in ELISA using: (i) the immunizing antigen and chemically synthesized derivatives thereof; (ii) chlamydial elementary bodies (EB); and (iii) LPS of Chl. psittaci 6BC and Chlamydia trachomatis L2. The specificity was determined in comparison to that of mAb S25-23 recognizing the alphaKdo(2-->8)alphaKdo(2-->4)alphaKdo trisaccharide which represents an epitope shared by all species of the family. MAb S45-18 bound to an epitope of the structure alphaKdo(2-->4)alphaKdo(2-->4)alphaKdo, with lower reactivity with the (2-->8)-(2-->4)-linked analog. Using chlamydial EB or LPS, mAb S45-18 bound preferentially to LPS and EB of Chl. psittaci. Therefore, Chl. psittaci LPS contains, in addition to the known genus-specific epitope, a species-specific epitope.

Mapping the binding of synthetic disaccharides representing epitopes of chlamydial lipopolysaccharide to antibodies with NMR.

A NMR study of the binding of the synthetic disaccharides alpha-Kdo-(2-->4)-alpha-Kdo-(2-->O)-allyl 1 (Kdo, 3-deoxy-D-manno-oct-2-ulopyranosonic acid) and alpha-Kdo-(2-->8)-alpha-Kdo-(2-->O)-allyl 2, representing partial structures of the lipopolysaccharide epitope of the intracellular bacteria Chlamydia, to corresponding monoclonal antibodies (mAbs) S23-24, S25-39, and S25-2 is presented. The conformations of 1 bound to mAbs S25-39 and of 2 bound to mAbs S23-24 and S25-39 were analyzed by employing transfer-NOESY (trNOESY) and QUIET-trNOESY experiments. A quantitative analysis of QUIET-trNOESY buildup curves clearly showed that S25-39 recognized a conformation of 1 that was similar to the global energy minimum of 1, and significantly deviated from the conformation of 1 bound to mAb S25-2. For disaccharide 2, only a qualitative analysis was possible because of severe spectral overlap. Nevertheless, the analysis showed that all mAbs most likely bound to only one conformational family of 2. Saturation transfer difference (STD) NMR experiments were then employed to analyze the binding epitopes of the disaccharide ligands 1 and 2 when binding to mAbs S23-24, S25-39, and S25-2. It was found that the nonreducing pyranose unit was the major binding epitope, irrespective of the mAb and the disaccharide that were employed. Individual differences were related to the engagement of other portions of the disaccharide ligands.

Epidemiologic association of Chlamydia pneumoniae and atherosclerosis: the initial serologic observation and more.

About 70% of persons with acute myocardial infarction (AMI) show a seroresponse to a chlamydial lipopolysaccharide (LPS) epitope. Elevated titers against Chlamydia pneumoniae in sera from such patients point to an exacerbation in a chronic infection as does a change in the nature of immune complexes containing chlamydial LPS. The presence of antibodies to C. pneumoniae proteins in immune complexes suggests an intimate association of the pathogen with the vascular system. In the first prospective study, elevated antibody titers or immune complexes containing chlamydial LPS were an independent significant risk factor (odds ratio, </=2.6) for AMI 3-6 months before the cardiac incident. The majority of later seroepidemiologic studies have verified the association. However, since serologic markers for C. pneumoniae infection also seem to be associated with uncomplicated atherosclerosis and other chronic conditions, their predictive value for cardiac events is small.

Chlamydial virulence determinants in atherogenesis: the role of chlamydial lipopolysaccharide and heat shock protein 60 in macrophage-lipoprotein interactions.

Data from a spectrum of epidemiologic, pathologic, and animal model studies show that Chlamydia pneumoniae infection is associated with coronary artery disease, but it is not clear how the organism may initiate or promote atherosclerosis. It is postulated that C. pneumoniae triggers key atherogenic events through specific virulence determinants. C. pneumoniae induces mononuclear phagocyte foam cell formation by chlamydial lipopolysaccharide (cLPS) and low-density lipoprotein oxidation by chlamydial hsp60 (chsp60). Thus, different chlamydial components may promote distinct events implicated in the development of atherosclerosis. Data implicating cLPS and chsp60 in the pathogenesis of atherosclerosis are discussed and novel approaches are presented for attempting to elucidate how these putative virulence determinants signal mononuclear phagocytes to modulate lipoprotein influx and modification.

Evaluation of a commercial test for antibodies to the chlamydial lipopolysaccharide (MedacTM ) for serodiagnosis of acute infections by Chlamydia pneumoniae (TWAR) and Chlamydia psittaci

A commercial test (rELISA) based on a recombinant chlamydial lipopolysaccharide (LPS) antigen has been evaluated for the diagnosis of acute infections caused by Chlamydia pneumoniae (TWAR) and Chlamydia psittaci. This test and a microimmunofluorescence test (MIF) were compared in 160 patients with community-acquired pneumonia. Seventeen of nineteen cases with significant titre changes detected by rELISA were confirmed by MIF. The two remaining cases not confirmed by MIF were considered false-positive reactions. One case positive by MIF only was judged not to be a true-positive reaction. All three cases occurred in patients with Mycoplasma pneumoniae infection and may be the result of a mitogenic effect. High antibody titres have been used to indicate acute C. pneumoniae infection. We found high MIF or rELISA titres to be equally common in patients and controls; no association between the two tests was detected. An unexpected cross-reactivity between the rELISA antigen and parvovirus was observed, which might have diagnostic implications. Both MIF and rELISA detected acute C. pneumoniae and C. psittaci infection, and there was good agreement between the tests. Single serum diagnosis was generally not feasible with either MIF or rELISA.

Characterization of high affinity monoclonal antibodies specific for chlamydial lipopolysaccharide.

Pathogens belonging to the genus Chlamydia contain lipopolysaccharide with a 3-deoxy-D- manno- oct-2-ulosonic acid (Kdo) trisaccharide of the sequence alpha-Kdo-(2-->8)-alpha-Kdo-(2-->4)-alpha-Kdo. This lipopolysaccharide is recognized in a genus-specific pattern by murine monoclonal antibodies (mAbs), S25-23 and S25-2 (both IgG1kappa), which bind as the minimal structures the trisaccharide and the terminal Kdo-disaccharide, respectively. The variable domains of these mAbs were reverse transcribed from mRNA which was isolated from hybridomas and cloned as single-chain variable fragments (scFvs) in E.coli TG1. The kinetics of binding of whole antibodies, Fab fragments and scFvs to natural and synthetically modified ligands were determined by surface plasmon resonance (SPR) using synthetic neoglycoconjugates. As examples of an antibody-carbohydrate interaction involving anionic carboxyl groups on the ligand, we report that the affinities of these antibodies are higher than usually observed in carbo-hydrate-protein interactions (K(D)of 10(-3)to 10(-5)M). SPR analy-ses of monovalent Fab and scFv binding to the natural trisaccharide epitope gave dissociation constants of 770 nM for S25-2 and 350 nM for S25-23, as determined by global fitting (simultaneous fitting of several measurements at different antibody concentrations) of sensorgram data to a one-to-one interaction model. Local fitting (separate fitting of individual sensorgram data at different antibody concentrations) and Scatchard analysis of the data gave kinetic and affinity constants that were in good agreement with those obtained by global fitting. The SPR data also showed that while S25-2 bound well to several Kdo disaccharides and carboxyl-reduced Kdo ligands, S25-23 did not. Identification of amino acids in the complementarity determining regions revealed the presence of a large number of positively charged amino acids which were located towards the center of the combining site, thus suggesting a different recognition mechanism than that observed for neutral ligands. The latter mainly involves aromatic amino acids for hydrophobic stacking inter-actions and hydrogen bonds.

Seropositivity to chlamydial lipopolysaccharide and chlamydia pneumoniae, systemic inflammation and stable coronary artery disease: Negative results of a case-control study

OBJECTIVESWe investigated the association between seropositivity to chlamydial lipopolysaccharide (cLPS) or Chlamydia pneumoniae (CP)and angiographically documented coronary artery disease (CAD), and we examined the relationship between serostatus and markers of systemic inflammation.BACKGROUNDThe potential contribution of CPto atherogenesis is still a matter of debate, and inflammation has been suggested to represent the link between infection and atherosclerotic disease.METHODSSubjects age 40 to 68 years were recruited for this case-control study between October 1996 and November 1997: 312 patients with at least one coronary stenosis >50% and 479 age- and sex-matched blood donors without manifest CAD or history of angina. Antibodies against cLPS and CP, C-reactive protein (CRP), fibrinogen, plasma viscosity, leukocytes and neutrophils were determined. The study had a power of >80% to detect an odds ratio (OR) of 1.55 or above for the prevalence of immunoglobulin (IgG) antibodies against cLPS at a significance level of alpha = 0.05.RESULTSPrevalence of IgG antibodies against cLPS was not different between cases and controls (61% vs. 62%; p = 0.7). The adjusted OR for the presence of CAD given positive IgG serostatus against cLPS was 0.9 (95% CI; 0.6 to 1.3). Similarly, no difference in the prevalence of IgG antibodies against CPwas seen (88% vs. 87%; p = 0.6); the adjusted OR was 1.0 (95% CI; 0.6 to 1.6). Markers of inflammation did not show any statistically significant difference between cLPS seropositives and seronegatives.CONCLUSIONSOur results indicate no strong association between CPand CAD, and increased systemic inflammation in patients with CAD does not seem to be due to seropositivity to cLPS or CP.

Chlamydia pneumoniae and atherosclerosis: Links to the disease process

Chlamydia pneumoniae is an obligate intracellular prokaryotic human pathogen responsible for a significant portion of atypical pneumonia and associated with a variety of chronic sequelae, the most significant of which is atherosclerosis. The organism is endowed with several attributes that may contribute to the development of atherosclerotic lesions or promote tissue damage at the site of an existing lesion. Two key events that are directly involved in the atherogenic process include the development of foam cells from macrophages and the oxidation of lipoproteins at the site of lesion development. The former process allows for deposition of cholesterol-containing low-density lipoprotein (LDL) and the latter can contribute directly to tissue damage locally. We have hypothesized that C pneumoniae may interact with mononuclear phagocytes in ways that are consistent with the view that this organism contributes to atherosclerotic lesion development. We have demonstrated that the presence of C pneumoniae causes macrophage foam cell formation and lipid oxidation with murine and human cells cocultured in the presence of LDL. In addition, we have provided evidence that implicates 2 putative chlamydial virulence factors in the development of these pathologic processes. Chlamydial lipopolysaccharide has been shown to cause macrophages to develop into foam cells in the presence of LDL, and the 60-kDa chlamydial heat shock protein (cHsp60), a known pathogenesis-inducing protein, has been found to contribute to oxidation of LDL in the presence of macrophages. Work is currently underway to define mechanisms involved in these processes and to further refine the putative role of C pneumoniae in atherogenesis and atherosclerotic lesion development. (Am Heart J 1999;138:S488-S490.)

Serological evidence of Chlamydia pneumoniae lipopolysaccharide antibodies in atherosclerosis of various vascular regions.

The role of Chlamydia pneumoniae in the pathogenesis of atherosclerosis has so far mainly been investigated in patients suffering from coronary heart disease; the other vascular regions have virtually been ignored. The aim of this study was to carry out a statistical survey of serological markers of a C. pneumoniae infection in patients with different patterns of atherosclerosis manifestation. 340 patients were examined for the atherosclerotic alteration of peripheral arteries of the lower limbs, carotid arteries and coronary arteries by ultrasound scan and/or angiography. Immunoglobulin(Ig)G and IgA-rELISA were used to measure chlamydial lipopolysaccharide antibodies. Species determination was performed using the IgG micro-immunofluorescence test. 24.0% of atherosclerotic cases (A) and 52.3% of controls (C) were negative for C. pneumoniae lipopolysaccharide antibodies (p = 0.00002). By contrast, 45.1% of atherosclerotic cases and 16.9% of controls were positive for both IgG and IgA (p = 0.00002). The mean antibody titers of the atherosclerosis group were higher than in the control group (IgG positive xAIgG = 344, xCIgG = 272; IgG and IgA positive xAIgG = 576, xCIgG = 486 and xAIgA = 120, xCIgA = 91). Concerning atherosclerosis manifestation in various vascular regions, no significant differences were found between IgG and IgA antibody titers and prevalence. The results show that a persistent C, pneumoniae infection with evidence of lipopolysaccharide immunoglobulin G and A is equally associated with the atherosclerotic alteration of coronary arteries, carotid arteries and peripheral arterial occlusive disease, irrespective of the severity of atherosclerosis and with no predisposition to any particular vascular region.

Antibodies to Chlamydia trachomatis heat shock proteins in women with tubal factor infertility are associated with prior infection by C. trachomatis but not by C. pneumoniae.

The antibody response to heat shock proteins 60 and 10 were studied in 163 patients with tubal factor infertility and in 163 age-matched pregnant women. The associations of these antibodies with specific antibodies to Chlamydia trachomatis and to Chlamydia pneumoniae as well as with antibodies to the common chlamydial lipopolysaccharide antigen were studied. Patients with tubal factor infertility had significantly higher frequencies and titres of all antibodies except to C. pneumoniae. In a logistic regression model an association was found between the prevalence of antibodies to the heat shock proteins and to C. trachomatis but no independent influence of antibodies to C. pneumoniae. No interaction between C. trachomatis and C. pneumoniae suggesting a synergistic effect was found although the heat shock proteins from these two organisms are immunologically similar. Antibodies to the chlamydial lipopolysaccharide also seemed to be related to C. trachomatis and not to C. pneumoniae in these women.