Impact of chronic Helicobacter pylori infection on Alzheimer's disease: preliminary results.

Recent case-control studies reported an association between H. pylori infection and Alzheimer's disease (AD). Our aim was to compare cognitive impairment, neuroinflammation, and cerebrovascular lesion load in a group of AD patients according to their H. pylori status. For the 53 AD patients included, we assessed: clinical data (vascular comorbidities and cognitive assessment), biological data (especially fibrinogen, homocysteine levels, apolipoprotein E4 genotype; cerebrospinal fluid [CSF] total tau protein [Tau], phospho-tau(181) protein [pTau(181)]), and amyloid beta peptide levels, serum/CSF-cytokines (interleukin [IL]-1ß, IL-6, IL-8, tumor necrosis factor [TNF]-α) and pepsinogen I/pepsinogen II (PgI/PgII) ratio, and cerebrovascular lesion load (magnetic resonance imaging [MRI] fluid-attenuated inversion recovery [FLAIR] with the Fazekas and Schmidt scale). H. pylori infection was diagnosed by enzyme-linked immunosorbent assay (ELISA) and immunoblot test. H. pylori infection was associated with a decreased Mini Mental State Examination (MMS) (p = 0.024), and higher CSF pTau(181) (p = 0.014) and tau (p = 0.021) levels. A decreased PgI/II ratio (i.e., an increased gastric atrophy) was associated with the infection (p = 0.005). Homocysteine levels were positively correlated to Fazekas score (r = 0.34; p = 0.032) and to H. pylori immunoglobulin (Ig)G levels (r = 0.44; p = 0.001). Higher CSF cytokine levels (IL-8, p = 0.003; TNF-α, p = 0.019) were associated with the infection, but systemic inflammation results were controversial. Finally, in multivariate analysis, a lower MMSE score (odds ratio [OR], 0.83 [0.72-0.97]; p = 0.017), plasma IL-1ß level (OR, 0.31 [0.11-0.87]; p = 0.025), an increased gastric atrophy, i.e., a lower PgI/PgII ratio (OR, 0.63 [0.43-0.93]; p = 0.020) were still associated with the infection. AD patients infected by H. pylori tended to be more cognitively impaired. Studies are needed to attest to the impact of H. pylori infection on AD course, especially on cerebrovascular lesions and neuroinflammation.

Infectious burden and risk of stroke: the northern Manhattan study.

OBJECTIVE: To determine the association between a composite measure of serological test results for common infections (Chlamydia pneumoniae, Helicobacter pylori, cytomegalovirus, and herpes simplex virus 1 and 2) and stroke risk in a prospective cohort study. DESIGN: Prospective cohort followed up longitudinally for median 8 years. SETTING: Northern Manhattan Study. Patients Randomly selected stroke-free participants from a multiethnic urban community. Main Outcome Measure Incident stroke and other vascular events. RESULTS: All 5 infectious serological results were available from baseline samples in 1625 participants (mean [SD] age, 68.4 [10.1] years; 64.9% women). Cox proportional hazards models were used to estimate associations of each positive serological test result with stroke. Individual parameter estimates were then combined into a weighted index of infectious burden and used to calculate hazard ratios and confidence intervals for association with risk of stroke and other outcomes, adjusted for risk factors. Each individual infection was positively, though not significantly, associated with stroke risk after adjusting for other risk factors. The infectious burden index was associated with an increased risk of all strokes (adjusted hazard ratio per standard deviation, 1.39; 95% confidence interval, 1.02-1.90) after adjusting for demographics and risk factors. Results were similar after excluding those with coronary disease (adjusted hazard ratio, 1.50; 95% confidence interval, 1.05-2.13) and adjusting for inflammatory biomarkers. CONCLUSIONS: A quantitative weighted index of infectious burden was associated with risk of first stroke in this cohort. Future studies are needed to confirm these findings and to further define optimal measures of infectious burden as a stroke risk factor.

Chlamydia pneumoniae infection enhances microglial activation in atherosclerotic mice.

The presence of Chlamydia pneumoniae in murine brain tissue was studied in atherosclerotic and non-atherosclerotic mice, after peritoneal injection. Furthermore, we investigated whether increased permeability of the blood-brain barrier was implicated in cerebral C. pneumoniae infection and whether intra-cerebral C. pneumoniae infection leads to microglial activation. Using a polymerase chain reaction, C. pneumoniae DNA was found in the brain tissue of 33% of the mice, 3, 7 and 21 days after infection. Atherosclerosis and age does not influence the extend of the cerebral infection. Semiquantitative analyses showed that intra-cerebral C. pneumoniae infection was not accompanied by an altered function of the blood-brain barrier. Microglial activation was assessed with immunohistochemistry, quantified in the hippocampus of each infected mouse and compared with mock infected. Enhanced microglial activation was found in the atherosclerotic mice. Since microglial activation is a key factor in a number of neuroinflammatory diseases, C. pneumoniae infection might play a role in these diseases.

Chlamydial infection and progression of carotid atherosclerosis in patients on regular haemodialysis.

BACKGROUND: Recent findings have suggested a possible contribution of chlamydial infection to the pathogenesis of atherosclerosis in the general population. However, the role that chlamydial antibody status plays in atherosclerosis generation in haemodialysis (HD) patients remains uncertain. METHODS: We measured carotid artery intima medial thickness (IMT) over 4 years in 100 HD subjects (age: 58+/-10 years; time on HD: 13+/-7 years; male/female: 67/33) and examined potential associations between Chlamydia pneumoniae (Cp) antibody seropositivity and changes in carotid artery IMT. RESULTS: During 4 years, carotid artery IMT increased significantly from 0.62+/-0.13 to 0.73+/-0.12 mm (P< 0.01). IMT progression was significantly and positively correlated with age (r = 0.37, P<0.01), log-transformed C-reactive protein (CRP; r = 0.33, P<0.01) and log-transformed interleukin-6 (IL-6; r = 0.22, P<0.04), but inversely correlated with blood creatinine (r = -0.36, P<0.01) and albumin (r = -0.24, P<0.02). IMT increases were more prominent in patients positive for IgA antibodies (0.039+/- 0.022 mm/year, n = 52) compared with those without IgA antibodies (0.025+/-0.032 mm/year, n = 48) (P<0.01). IgA seropositivity did not accelerate IMT progression in patients with increased CRP (>0.11 mg/dl, n = 53), but significantly increased IMT to a greater extent in IgA-positive subjects than in IgA-negative subjects having lower CRP (

No evidence of involvement of Chlamydia pneumoniae in severe cerebrovascular atherosclerosis by means of quantitative real-time polymerase chain reaction.

BACKGROUND AND PURPOSE: All studies reporting high numbers of Chlamydia pneumoniae DNA positives in stroke patients published to date have used polymerase chain reaction (PCR) techniques highly prone to generate false-positive results. The aim of this study was to analyze the prevalence of C. pneumoniae DNA in plaques of the carotid artery as well as in peripheral blood by means of a new, closed, real-time PCR system. METHODS: Carotid endarterectomy specimens and preoperative peripheral blood mononuclear cells (PBMC) of 75 individuals with severe cerebrovascular atherosclerosis were analyzed by means of a C. pneumoniae-specific quantitative ompA-based real-time PCR TaqMan system. Plaques were also cultured onto HEp-2 cells. Before the surgical intervention, C. pneumoniae-specific IgM, IgG, and IgA as well as C-reactive protein (CRP) levels were determined. RESULTS: 89% of all patients studied had C. pneumoniae-specific antibodies, but the pathogen was not detected in a single carotid atheroma by real-time PCR and cell culture. However, C. pneumoniae DNA was detected in 4 PBMC samples (5.3%) at very low levels (<1 inclusion/6 mL EDTA blood). No statistical significance was found between symptomatic/asymptomatic patients, C. pneumoniae PCR, results and CRP values after correction for multiplicity-of-test adjustment. CONCLUSIONS: By means of a closed, highly sensitive, and specific real-time PCR, C. pneumoniae was not detected in cerebrovascular atherosclerosis. PCR on PBMC was not predictive for endovascular chlamydia infection and most likely stem from previous C. pneumoniae respiratory tract infection in individual cases.

Association of Chlamydia pneumoniae with central nervous system disease.

Chlamydia pneumoniae is a common respiratory pathogen that is now being incriminated in a number of chronic diseases. The ability of C. pneumoniae to infect and persist in macrophages makes it a likely candidate to disseminate in a number of different tissues, including those of the central nervous system. This review addresses the potential and the underlying mechanisms by which C. pneumoniae infections can play a role in such diverse neurological diseases as multiple sclerosis and Alzheimer's disease.

Chlamydia pneumoniae in atherosclerotic middle cerebral artery.

BACKGROUND AND PURPOSE: Atherosclerotic middle cerebral arteries are frequent sites of thrombosis, leading to stroke. Previous studies have suggested a role for Chlamydia pneumoniae in the pathogenesis of atherosclerosis. However, the presence of this pathogen in atherosclerotic middle cerebral arteries has heretofore not been documented. In the present study, we analyzed atheromatous plaques from middle cerebral arteries for the presence of C pneumoniae. METHODS: Atherosclerotic middle cerebral arteries from 15 cadavers who died of natural causes and corresponding nonatherosclerotic arteries from 4 otherwise healthy trauma victims were examined. Assays for C pneumoniae DNA were carried out by nested polymerase chain reaction (nPCR) specific for the C pneumoniae ompA gene. The presence of the bacterium was assessed by transmission electron microscopy. RESULTS: Five of the 15 atherosclerotic arterial samples and none of the control tissues were positive for C pneumoniae by nPCR. Particles similar in morphology and size to C pneumoniae elementary bodies were detected by transmission electron microscopy in 4 of the 5 nPCR-positive atherosclerotic samples. CONCLUSIONS: The demonstration of C pneumoniae in atherosclerotic middle cerebral arteries is consistent with the hypothesis that this bacterium is involved in acute and chronic cerebrovascular diseases.

[The presence of anti-Chlamydia pneumoniae antibodies in peripheral vascular and neurological disorders]. / Presencia de anticuerpos anti-Chlamydia pneumoniae en procesos vasculares periféricos y neurológicos.

OBJECTIVES: To make a retrospective analysis of the synthesis of antibodies to the MOMPS and LPS antigens of Chlamydia pneumoniae in patients with occlusive disease of the peripheral arteries (ODPA) and multiple sclerosis (MS). PATIENTS AND METHODS: We studied 190 samples of plasma from patients included in the following groups: group 1:66 samples from 66 patients with ODPA; group 2:74 samples from 31 patients with MS (20 remittent-relapsing and 11 secondarily progressive), followed over time; and group 3:50 samples from persons acting as controls. In all cases determinations were made using ELISA, of the IgG anti-MOMP and the IgG and IgA anti-LPS. Comparison of the continuous variables was made using the Mann-Whitney U Test. Discrete variables were analysed using the exact bilateral Fisher Test. The Wilcoxon Test over ranges was used to compare the evolution of antibodies in the patients with MS. RESULTS: The percentage of positive results in groups 1 to 3 for anti-LPS IgG were: 24.6%, 18.9% and 20.8%, respectively, with no differences between patients and controls; nor were there any differences with IgA (29%, 29.7% and 25%, respectively). However differences were seen in the anti-MOMP IgG between patients and controls (group 1:80.3%, group 2:37.8% and group 3: 33.3%). In patients with MS the results of the evolution of the antibodies did not reflect a uniform tendency of the levels of the different antibodies. CONCLUSION: A higher level of IgG anti-MOMP was seen in ODPA and MS, although this did not occur with anti-LPS or IgA.

Chlamydia pneumoniae infection of the central nervous system.

Chlamydia pneumoniae is a common respiratory pathogen that is now being implicated in a number of chronic diseases. That the organism can infect vascular endothelium, macrophages and smooth muscle cells suggests that it may play a role in many systemic diseases. The present review focuses on the possibility that the central nervous system can also be a target of this agent. The tropism of C. pneumoniae to the neural tissue suggests it may play a role in diverse neurologic diseases, including Alzheimer's disease, multiple sclerosis and giant-cell arteritis.

Chlamydia pneumoniae and the risk of first ischemic stroke : The Northern Manhattan Stroke Study.

BACKGROUND AND PURPOSE: Serological evidence of infection with Chlamydia pneumoniae has been associated with cardiovascular disease in multiple epidemiological studies. The data on its association with ischemic stroke are limited. We sought to determine whether chronic C pneumoniae infection is associated with ischemic stroke in a multi-ethnic population. METHODS: The Northern Manhattan Stroke Study contains a population-based, case-control study component. Cases had first ischemic stroke and matched control subjects were derived through random digit dialing. Titers of IgG, IgA, and IgM antibodies specific for C pneumoniae were measured with the use of microimmunofluorescence, and titers >/=1:16 were considered positive. Conditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (95% CIs) after adjustment for medical, behavioral, and socioeconomic factors. RESULTS: Eighty-nine cases and 89 control subjects were selected. Mean age among cases was 68.5+/-12.8 years; 53% were women and 15% of the subjects were white, 28% were black, and 54% were Hispanic. Elevated C pneumoniae IgA titers were significantly associated with risk of ischemic stroke after adjusting for other stroke risk factors (adjusted OR 4. 51, 95% CI 1.44 to 14.06). IgG titers were less strongly associated with stroke risk (adjusted OR 2.59, 95% CI 0.87 to 7.75). The association of IgA with stroke risk was detected in both younger and older groups, in men and women, and in whites, blacks, and Hispanics. There was also a significant continuous increase in risk associated with the log-transformation of the titer for IgA (adjusted OR 1.32, 95% CI 1.05 to 1.66) but not IgG. CONCLUSIONS: Serological evidence of chronic infection with C pneumoniae is associated with risk of ischemic stroke in an urban, multi-ethnic population. IgA titers may be a better marker of this risk than are IgG titers. This association is independent of other vascular disease risk factors. Further prospective epidemiological studies of the effect of this infection on stroke risk are warranted.

Chlamydia pneumoniae antigens, rather than viable bacteria, persist in atherosclerotic lesions.

AIMS: To evaluate the nature of the presence of Chlamydia pneumoniae or of other members of the order Chlamydiales in atherosclerotic lesions. METHODS: Consecutive sections of 13 carotid artery specimens obtained at necropsy and of C pneumoniae infected HEp2 cells were analysed using: (1) immunocytochemistry (ICC) to detect C pneumoniae membrane protein; (2) in situ hybridisation (ISH) using a polymerase chain reaction (PCR) fragment of the omp1 gene to detect C pneumoniae specific DNA; (3) ISH using an oligonucleotide probe to detect Chlamydiales specific 16S rRNA; (4) PCR to detect C pneumoniae 16S rDNA; and (5) in situ DNA nick and labelling (TUNEL) to detect fragmented DNA. RESULTS: Staining by ICC and ISH of infected HEp2 cells showed characteristic inclusions. Chlamydia pneumoniae membrane protein was demonstrated in macrophages in advanced atherosclerotic lesions (six of six), but not in fatty streaks (none of two), or normal arteries (none of five). ISH assays using both probes and PCR were all negative, indicating the absence of both specific C pneumoniae DNA and Chlamydiales specific 16S rRNA. Only after treatment with DNAse I were uniformly sized dots demonstrated by the TUNEL assay in inclusions of infected HEp2 cells. The TUNEL assay showed a similar staining pattern in macrophages in five carotid artery specimens, of which four were also positive for C pneumoniae membrane protein. Both macrophage populations were morphologically similar and were similarly distributed. CONCLUSIONS: No evidence was obtained for the involvement of other members of the order Chlamydiales in atherosclerosis. The presence of C pneumoniae antigen in the absence of DNA and 16S rRNA suggests that antigens, rather than viable bacteria, persist in atherosclerotic lesions.

Demonstration of viable Chlamydia pneumoniae in atherosclerotic plaques of carotid arteries by reverse transcriptase polymerase chain reaction.

The presence of Chlamydia pneumoniae in atheromas has been demonstrated in several studies. Culture of the organism from arterial tissue has been difficult. We report the use of a reverse transcriptase polymerase chain reaction to detect viable Chlamydia pneumoniae in carotid atheromas. We analyzed 30 patients (14 females, mean age 69.6 +/- 8.8 years) who underwent surgery for the removal of atherosclerotic plaques from carotid arteries. During surgery, samples of lingual vein and superior thyroideal artery were also taken. We applied two molecular biology techniques to the carotid plaques on lingual vein or thyroideal artery samples: 1) polymerase chain reaction (PCR) and 2) reverse transcriptase-PCR (RT-PCR) for the detection of bacterial mRNA, employing PCR primers designed to detect a fragment of the 16S rRNA gene. Blood samples were obtained from the patients for determination of Chlamydia pneumoniae IgG, IgA, and IgM antibody titers by a microimmunofluorescence technique. The results of the present study confirmed the presence of viable Chlamydia pneumoniae in atheromas and support the hypothesis that the organism may be an active factor in the pathogenesis of atherosclerosis.

Chlamydia pneumoniae (TWAR) in atherosclerosis of the carotid artery.

BACKGROUND: Chlamydia pneumoniae has been demonstrated in atherosclerotic lesions of coronary arteries and aorta. A seroepidemiological study found C pneumoniae-specific antibody more frequently in persons with significant carotid artery wall thickening than in matched control subjects. METHODS AND RESULTS: Fresh-frozen or formalin-fixed tissue obtained at carotid endarterectomy was examined by immunocytochemistry (ICC) and the polymerase chain reaction (PCR) for the presence of C pneumoniae. Five of five fresh-frozen and formalin-fixed carotid endarterectomy specimens were positive for C pneumoniae by ICC (three of five by PCR). A total of 56 archival formalin-fixed, paraffin-embedded carotid endarterectomy tissues from three hospitals were examined by ICC. Thirty-two were positive. Thirteen normal carotid artery tissue sections from six patients were negative for C pneumoniae. CONCLUSIONS: C pneumoniae organisms are frequently found in the advanced carotid atherosclerotic lesions of persons undergoing endarterectomy. Although these findings do not establish causality for C pneumoniae in carotid artery atherosclerosis, they should stimulate investigation of a possible causal or pathogenic role for the organism in the disease.