Association of chlamydial infection with cerebrovascular disease

Infectious origin of Alzheimer’s disease: Amyloid beta as a component of brain antimicrobial immunity

The amyloid cascade hypothesis, focusing on pathological proteins aggregation, has so far failed to uncover the root cause of Alzheimer’s disease (AD), or to provide an effective therapy. This traditional paradigm essentially explains a mechanism involved in the development of sporadic AD rather than its cause. The failure of an overwhelming majority of clinical studies (99.6%) demonstrates that a breakthrough in therapy would be difficult if not impossible without understanding the etiology of AD. It becomes more and more apparent that the AD pathology might originate from brain infection. In this review, we discuss a potential role of bacteria, viruses, fungi, and eukaryotic parasites as triggers of AD pathology. We show evidence from the current literature that amyloid beta, traditionally viewed as pathological, actually acts as an antimicrobial peptide, protecting the brain against pathogens. However, in case of a prolonged or excessive activation of a senescent immune system, amyloid beta accumulation and aggregation becomes damaging and supports runaway neurodegenerative processes in AD. This is paralleled by the recent study by Alam and colleagues (2022) who showed that alpha-synuclein, the protein accumulating in synucleinopathies, also plays a critical physiological role in immune reactions and inflammation, showing an unforeseen link between the 2 unrelated classes of neurodegenerative disorders. The multiplication of the amyloid precursor protein gene, recently described by Lee and collegues (2018), and possible reactivation of human endogenous retroviruses by pathogens fits well into the same picture. We discuss these new findings from the viewpoint of the infection hypothesis of AD and offer suggestions for future research.

More than a century after its discovery, Alzheimer’s disease (AD) remains incurable and mysterious. The dominant hypothesis of amyloid cascade has succeeded in explaining the key pathological mechanism, but not its trigger. Amyloid beta has been traditionally considered a pathological peptide, and its physiological functions remain poorly known. These knowledge gaps have contributed to repeated failures of clinical studies. The emerging infectious hypothesis of AD considers central nervous system (CNS) infection the primary trigger of sporadic AD. A closely connected hypothesis claims that amyloid beta is an antimicrobial peptide. In this review, we discuss the available evidence for the involvement of infections in AD, coming from epidemiological studies, post mortem analyses of brain tissue, and experiments in vitro and in vivo. We argue there is no unique “Alzheimer’s germ,” instead, AD is a general reaction of the CNS to chronic infections, in the milieu of an aged immune system. The pathology may become self-sustained even without continuous presence of microbes in the brain. Importantly, the infectious hypothesis leads to testable predictions. Targeting amyloid beta should be ineffective, unless the triggering pathogen and inflammatory response are addressed as well. Meticulous control of selected infections might be the best near-term strategy for AD prevention.

Intracranial Large Artery Stenosis and Past Infectious Exposures: Results From the NOMAS Cohort

BACKGROUND

Intracranial large artery stenosis (ILAS) is an important contributor to ischemic stroke in the United States and worldwide. There is evidence to suggest that chronic exposure to certain infectious agents may also be associated with ILAS. We aimed to study this association further in an ethnically diverse, prospective, population-based sample of Northern Manhattan.

METHODS

We enrolled a random sample of stroke-free participants from an urban, racially, and ethnically diverse community in 1993. Participants have been followed prospectively and a subset underwent brain magnetic resonance angiograms from 2003 to 2008. Intracranial stenoses of the circle of Willis and vertebrobasilar arteries were scored as 0=no stenosis, 1≤50% (or luminal irregularities), 2=50% to 69%, 3≥70% stenosis, and 4=flow gap. We summed the individual score of each artery to produce a global ILAS score (possible range, 0-44). Past infectious exposure to Chlamydia pneumoniae, Helicobacter pylori, cytomegalovirus, and herpes simplex virus 1 and 2 was determined using serum antibody titers.

RESULTS

Among 572 NOMAS (Northern Manhattan Study) participants (mean age 71.0±8.0 years, 60% women, 68% Hispanic) with available magnetic resonance angiogram and serological data, herpes simplex virus 2 (beta=0.051, P<0.001) and cytomegalovirus (beta=0.071, P<0.05) were associated with ILAS score after adjusting for demographics and vascular risk factors. Stratifying by anterior and posterior circulations, herpes simplex virus 2 remained associated with the anterior circulation (beta=0.055 P<0.01) but not with posterior circulation ILAS score.

CONCLUSIONS

Chronic infectious exposures, specifically herpes simplex virus 2 and cytomegalovirus were associated with asymptomatic ILAS as seen on magnetic resonance angiogram imaging. This may represent an additional target of intervention in the ongoing effort to stem the substantial global burden of strokes related to ILAS.

Association between hypertensive pregnancy disorders and future risk of stroke in Taiwan: a Nationwide population-based retrospective case-control study

Background

The incidence of female stroke has increased gradually and has begun occurring at a younger age in recent years. Given that women live longer than men, stroke would cause more negative and longer-term impacts on the rest of the lives of women. There are few related studies on Asian women. We aimed to evaluate stroke risk in Asian women following hypertensive pregnancy disorders.

Methods

Using the Taiwan National Health Insurance database, we designed a retrospective study that included pregnant women between 2000 and 2013. We selected an age-matched control group of women without hypertensive pregnancy disorders at a 1:3 ratio. The endpoint was any episode of stroke; otherwise, the patients were tracked until December 31, 2013. After the index date until the end of 2013, Cox proportional hazards analysis was used to compare the risk of incident stroke. The risk factors for stroke were determined using Cox proportional regression to calculate the hazard ratio (HR) compared with the control group.

Results

During the follow-up period, the Kaplan-Meier analysis indicated that patients with hypertensive pregnancy disorders had a significantly higher risk of developing stroke than did patients without hypertensive pregnancy disorders (log-rank test P < 0.001). Multivariate Cox regression analysis demonstrated that the case group had a 2.134-fold increased risk of stroke (HR = 2.134; 95% CI = 1.817–2.505; P < 0.001).

Conclusion

Our study provided evidence of an increased risk of stroke in patients with hypertensive pregnancy disorders. Compared with those without such disorders, the patients who had experienced the disorders had a 2.134-fold (P < 0.001) higher risk of developing stroke in the future.

Assessment of evidence for or against contributions of Chlamydia pneumoniae infections to Alzheimer's disease etiology

Alzheimer's disease, the most common form of dementia, was first formally described in 1907 yet its etiology has remained elusive. Recent proposals that Aβ peptide may be part of the brain immune response have revived longstanding contention about the possibility of causal relationships between brain pathogens and Alzheimer's disease. Research has focused on infectious pathogens that may colonize the brain such as herpes simplex type I. Some researchers have proposed the respiratory bacteria Chlamydia pneumoniae may also be implicated in Alzheimer's disease, however this remains controversial. This review aims to provide a balanced overview of the current evidence and its limitations and future approaches that may resolve controversies. We discuss the evidence from in vitro, animal and human studies proposed to implicate Chlamydia pneumoniae in Alzheimer's disease and other neurological conditions, the potential mechanisms by which the bacterium may contribute to pathogenesis and limitations of previous studies that may explain the inconsistencies in the literature.

Cross-Reactivity as a Mechanism Linking Infections to Stroke

The relevance of infections as risk factor for cerebrovascular disease is being increasingly recognized. Nonetheless, the pathogenic link between the two entities remains poorly understood. Consistent with recent advances in medicine, the present work addresses the hypothesis that infection-induced immune responses may affect human proteins associated with stroke. Applying established procedures in bioinformatics, the pathogen antigens and the human proteins were searched for common sequences using pentapeptides as probes. The resulting data demonstrate massive peptide sharing between infectious pathogens-such as Chlamydia pneumoniae, Streptococcus pneumoniae, Tannerella forsythia, Haemophilus influenzae, Influenza A virus, and Cytomegalovirus-and human proteins related to risk of ischemic and hemorrhagic stroke. Moreover, the shared peptides are also evident in a number of epitopes experimentally proven immunopositive in the human host. The present findings suggest cross-reactivity as a potential mechanistic link between infections and stroke.

Novel inflammatory biomarkers and their correlation to Chlamydia pneumoniae titres in acute ischemic stroke

BACKGROUND

Young stroke patients constitute 15%-30% of all stroke patients in India as against 3.0%-8.5% reported from the West. The mechanisms for stroke in the young may include unconventional risk factors such as infections. We aimed to investigate the role (if any) of Chlamydia pneumoniae antibodies in young patients with acute ischemic stroke (AIS). Several proinflammatory cytokines and biomarkers are released early after the onset of brain ischemia. We assessed the role of heat shock protein (hsp) 65, neopterin, and myeloperoxidase upregulation after AIS in predicting stroke severity. We also assessed relationship of upregulated inflammatory biomarkers with C pneumoniae antibody titres (IgG, IgA, and IgM).

METHODS

Eighty acute stroke patients and healthy age- and sex-matched controls were recruited. Blood samples were drawn within 1 week from the onset of stroke. Detection of IgA, IgG, and IgM antibodies to C pneumoniae was done with a validated microimmunofluorescence technique from 5 mL of serum in all subjects. Inflammatory biomarkers such as neopterin, myeloperoxidase and hsp 65 were estimated with sandwich enzyme linked immunosorbent assay (ELISA) method.

RESULTS

hsp 65 and neopterin were significantly elevated in all stroke patients with respect to healthy controls (odds ratio [OR], 4.9; 95% confidence interval [CI], 23.5-67.8; P = .001 and OR, 4.4; 95% CI, 2.08-9.4; P = .04, respectively). Eighty-one percent of cases were seropositive for IgA versus 32% of controls (P = .003), and IgG was positive in 52.7% versus 17.3% of controls (P = .05). Myeloperoxidase levels were similar in patients and controls. Correlation and multiple regression indicated a high level of predictability and sensitivity of hsp 65 to IgA. C. pneumoniae antibody titres when all other variables were constant (F [4,90] = -6.8, P = .001). Patients with high NIHSS scores (>15) had elevated levels of hsp 65 (mean, 13.2 ng/mL) suggesting correlation with stroke severity.

CONCLUSIONS

The study demonstrated high levels of hsp 65 and neopterin levels in AIS correlated to significantly elevated IgA titres of C pneumoniae. Elevated levels of hsp 65 were associated with stroke severity.

Previous infection and the risk of ischaemic stroke in Italy: the IN2 study

BACKGROUND AND PURPOSE

There is an increasing interest in new risk factors for ischaemic stroke. Acute and chronic infections could contribute to different aetiological mechanisms of atherosclerosis that lead to cerebrovascular disease. The aim of this study was to investigate the hypothesis that previous infections and Chlamydia pneumoniae in particular increase the risk of ischaemic stroke in the population.

METHODS

This was a prospective case-control study involving 11 Italian stroke units. Controls were age- and sex-matched with cases, represented by patients admitted to hospital for acute ischaemic stroke. For each participant classical vascular risk factors and previous inflammatory and infectious events up to 1 month before were registered. Blood samples were collected to analyse inflammatory markers and titres of antibodies against C. pneumoniae.

RESULTS

A total of 1002 participants were included (mean age 69 years) with 749 ischaemic stroke patients. Infections occurred within 1 month previously in 12% of the entire sample with a higher prevalence in the case group (14.4% vs. 3.9%). At multivariate analysis of the seropositivity of IgA antibodies against C. pneumoniae increased the risk of stroke significantly (relative risk 2.121; 95% confidence interval 1.255-3.584) and an early previous infection (up to 7 days before the event) contributed to a rise in probability of acute cerebral ischaemia (relative risk 3.692; 95% confidence interval 1.134-6.875).

CONCLUSIONS

Early previous infections and persistent chronic infection of C. pneumoniae could contribute to increase the risk of ischaemic stroke significantly, in the elderly especially.

Chlamydia pneumoniae infection and cerebral infarction risk: a meta-analysis

BACKGROUND

Chlamydia pneumoniae infection and the risk of cerebral infarction have been previously studied in several publications; however, conflicting results have been reported. This meta-analysis assessed whether C. pneumoniae infection was associated with risk of cerebral infarction.

METHODS

Systematic computerized searches of the PubMed and Web of Knowledge were performed. Adjusted odds ratio and 95% confidence interval from original studies were extracted for combined meta-analysis.

RESULTS

Twenty-three studies with 2924 cerebral infarction patients and 4692 control patients were included in the meta-analysis. When the positive C. pneumoniae infection was defined by microimmunofluorescence-detected immunoglobulin A, the pooled odds ratio between two groups was 2.04 (95% confidence interval 1.42-2.9). In the most frequently used immunoglobulin A ≥1:16 sub-group, the pooled odds ratio was 2.07 (95% confidence interval 1.31-3.26). When the infection was defined by enzyme-linked immunosorbent assay-detected immunoglobulin A, the pooled odds ratio was 2.89 (95% confidence interval 1.23-6.81). When the infection was defined by microimmunofluorescence-detected immunoglobulin G, the pooled odds ratio was 1.46 (95% confidence interval 1.18-1.81). In the most frequently used immunoglobulin G ≥1:32 sub-group, the pooled odds ratio was 1.43 (95% confidence interval 1.06-1.92). When the infection was defined by enzyme-linked immunosorbent assay-detected immunoglobulin G, the pooled odds ratio was 1.54 (95% confidence interval 0.86-2.74). No significant publication bias was found. Sensitivity analyses showed the results were robust.

CONCLUSION

(1) This meta-analysis indicated that C. pneumoniae infection was significantly associated with an increased risk of cerebral infarction. (2) Compared with anti-C. pneumoniae immunoglobulin G, anti-C. pneumoniae immunoglobulin A seemed more effective for predicting the risk of cerebral infarction. (3) No evidence existed that anti-C. pneumoniae-immunoglobulin G detected by enzyme-linked immunosorbent assay could predict the risk of cerebral infarction.

Association between Chlamydophila pneumoniae infection and risk of coronary heart disease for Japanese: the JPHC study

BACKGROUND

Chlamydophila pneumoniae infection is considered a risk factor for atherosclerosis and coronary heart disease in western countries. However, evidence of it being a risk for Japanese is very limited because of a lower risk of coronary heart disease than for western people. The aim of this study was to examine further the association between C. pneumoniae infection and risk of coronary heart disease in Japanese.

METHODS

We conducted a nested case-control study of 49,011 Japanese men and women who participated in The Japan Public Health Center (JPHC) study. By the end of 2004, 196 cases of coronary heart disease and 155 cases of myocardial infarction had been documented among the participants. Two controls were selected for each case. For these subjects, we examined the association between serum anti C. pneumoniae IgA and IgG on the one hand and risk of coronary heart disease on the other.

RESULTS

Concentration of C. pneumoniae IgA antibody was positively associated with risk of coronary heart disease and more specifically myocardial infarction. Subjects with the highest quartile of IgA antibody showed 2.29 (95%CI, 1.21-4.33) times higher risk of coronary heart disease and 2.58 (95%CI, 1.29-5.19) times higher risk of myocardial infarction than those with lowest quartile. However, no such association was detected for IgG antibody.

CONCLUSION

C. pneumoniae infection was found to be positively associated with risk of coronary heart disease.

Chlamydia pneumoniae infection and cerebrovascular disease: a systematic review and meta-analysis

Background

A wealth of published studies have been published on association between Chlamydia pneumoniae (C.pneumoniae) infection and cerebrovascular (CV) disease, but the results were inconsistent. This meta-analysis provides a systematic review of the available evidence from all serological and pathological studies of CV disease and C.pneumoniae.

Methods

A comprehensive research was conducted of MEDLINE, EMBASE, CNKI, WanFang technological periodical database and reference lists of articles to identify eligible case-control and cohort studies. Odds radio (OR) was calculated for each study outcome. Random effect model was used as pooling method and publication bias was estimated for the results.

Results

Fifty-two published studies that met criteria were selected. In case control studies, an association between C.pneumoniae infection and CV disease was revealed by serum specific IgG (OR, 1.61; 95% CI: 1.34 to 1.94), serum IgA (OR, 2.33; 95% CI: 1.76 to 3.08) and PCR technique of C.pneumoniae in peripheral blood cells (OR, 1.90; 95% CI: 1.17 to 3.07). No significant association was found in serum anti-C.pneumonae IgM seropositivity or in-situ-detection of C.pneumoniae in arterial biopsies with CV disease. Subgroup analysis by available studies suggested that C.pneumoniae may paly a role in atherosclerotic stroke, but be less significant in stroke of cardioembolism or other etiologies.

Conclusion

Association between C.pneumoniae infection and CV disease depends on the analytical method adopted, which seems stronger with stroke due to large artery atherosclerosis. Establishing a causal relationship between C.peumoniae infection and CV disease will require more prospective studies with combination of techniques and stratified by etiological subtypes.

Acute Glomerulonephritis in a Child with Chlamydia pneumoniae Infection: A Case Report

Background. Infectious diseases seem to be an important and independent risk factor for renal failure, but the underlying mechanism of renal involvement during some kinds of infectious diseases is still unclear, even if the literature data report immunomediated and/or autoimmune mechanisms to explain the pathogenic relationship between the two diseases. In paediatric patients, Chlamydia pneumoniae is a rare cause of renal complications and it may manifest in several ways, mainly involving the respiratory system, even if also renal and glomerulalr complications, have been described. Case Diagnosis/Treatment. Herein we report a case of a 3-year-old child who developed an acute glomerulonephritis that was chronologically, clinically, and biologically related to a previous Chlamydia pneumoniae infection. On our knowledge, in the literature it is the youngest patient with renal involvement during course of Chlamydia pneumoniae infection ever reported. Conclusions. The present case supports the hypothesis of a rather close causal relationship between this infective agent and renal and glomerular symptoms occurred in this child, during an acute episode of respiratory disease.

Genus-optimized strategy for the identification of chlamydial type III secretion substrates

Among chlamydial virulence factors are the type III secretion (T3S) system and its effectors. T3S effectors target host proteins to benefit the infecting chlamydiae. The assortment of effectors, each with a unique function, varies between species. This variation likely contributes to differences in host specificity and disease severity. A dozen effectors of Chlamydia trachomatis have been identified; however, estimates suggest that more exist. A T3S prediction algorithm, SVM-based Identification and Evaluation of Virulence Effectors (SIEVE), along with a Yersinia surrogate secretion system helped to identify a new T3S substrate, CT082, which rather than functioning as an effector associates with the chlamydial envelope after secretion. SIEVE was modified to improve/expand effector predictions to include all sequenced genomes. Additional adjustments were made to the existing surrogate system whereby the N terminus of putative effectors was fused to a known effector lacking its own N terminus and was tested for secretion. Expansion of effector predictions by cSIEVE and modification of the surrogate system have also assisted in identifying a new T3S substrate from C. psittaci. The expanded predictions along with modifications to improve the surrogate secretion system have enhanced our ability to identify novel species-specific effectors, which upon characterization should provide insight into the unique pathogenic properties of each species.

A new look at chronicChlamydiainfections and the role of the MHC/HLA in diseases of the CNS

Chlamydia has attracted increased attention as a possible cause of atheromatous plaques, cerebrovascular diseases, multiple sclerosis, Alzheimer’s disease and schizophrenia. The Chlamydia species are obligate intracellular parasites. The unique biphasic life cycle of Chlamydia permits the parasite to persist in cells for years. Acute Chlamydia infections can be recognized serologically in the peripheral blood through observation of rising antibody titers or molecularly using various PCR methods. However, the identification of chronic Chlamydia infection is hampered by many hurdles. This has initiated controversial discussions about the true involvement of Chlamydia, particularly in the CNS. The aspects of the discussion will be inspected as well as the vulnerability of the neuronal MHC to immune reactions.

Chlamydia pneumoniae infection in adolescents with type 1 diabetes mellitus

Chlamydia pneumoniae, an intracellular bacterium, is associated with respiratory diseases, reinfectivity and chronic diseases such as cardiovascular disease, hypertension and stroke. The risk of infection is higher and infections are a serious clinical problem in patients with type 1 (insulin-dependent) diabetes mellitus (T1DM). Although diabetes mellitus and hyperglycaemia are considered possible risk factors for various types of aetiological agents, the epidemiological evidence concerning C. pneumoniae infection is scanty. The aim of the present study was to evaluate the impact of glycosylated haemoglobin (HbA1c) levels, an indicator of a hyperglycaemic state, on C. pneumoniae infection and disease chronicity; in addition we compared the duration of diabetes with the occurrence of C. pneumoniae infection. C. pneumoniae blood real time PCR and serology (IgG, IgA and IgM) assays by an ELISA method were performed. C. pneumoniae DNA was detected in 46.5 % [95 % confidence interval (CI) = 35.1-57.9 %] of the patients with T1DM; this prevalence is higher (P<0.05) than in non-diabetic paediatric controls, 10.5 % (95 % CI = 3.6-17.4 %). IgG/IgA C. pneumoniae antibody positivity was significantly (P≤0.05) more common in patients in poor metabolic control (HbA1c >9 %) versus patients in good metabolic control (HbA1c <7 %), suggesting that the metabolic control of the disease is compromised in the patients with T1DM. In conclusion, adolescents with T1DM were more likely to show signs of infection with C. pneumoniae compared with healthy adolescents and the results suggest an increased risk of progressing from an acute C. pneumoniae infection to a chronic form.

Human neutrophil alpha-defensins induce formation of fibrinogen and thrombospondin-1 amyloid-like structures and activate platelets via glycoprotein IIb/IIIa

BACKGROUND

Human neutrophil α-defensins (HNPs) are important constituents of the innate immune system. Beyond their antimicrobial properties, HNPs also have pro-inflammatory features. While HNPs in plasma from healthy individuals are barely detectable, their level is strongly elevated in septic plasma and plasma from patients with acute coronary syndromes.

OBJECTIVES

As thrombosis and inflammation are intertwined processes and activation of human polymorphonuclear leukocytes (PMNL) and subsequent degranulation is associated with full activation of surrounding platelets, we studied the effect of HNPs on platelet function.

METHODS

The effect of HNPs on platelet activation parameters and apoptosis was investigated via aggregometry, flow cytometry, confocal microscopy and the ELISA technique.

RESULTS

It was found that HNPs activate platelets in pathophysiologically relevant doses, inducing fibrinogen and thrombospondin-1 binding, aggregation, granule secretion, sCD40L shedding, and procoagulant activity. HNPs bound directly to the platelet membrane, induced membrane pore formation, microparticle formation, mitochondrial membrane depolarization and caspase-3-activity. Confocal microscopy revealed the HNP-induced formation of polymeric fibrinogen and thrombospondin-1 amyloid-like structures, which bound microorganisms. Platelets adhered to these structures and formed aggregates. Blocking of glycoprotein IIb/IIIa (GPIIb/IIIa) markedly inhibited HNP-induced platelet activation. In addition, heparin, heparinoid, serpins and α(2)-macroglobulin, which all bind to HNPs, blocked HNP-1-induced platelet activation in contrast to direct thrombin inhibitors such as hirudin.

CONCLUSIONS

HNPs activate platelets and induce platelet apoptosis by formation of amyloid-like proteins. As these structures entrapped bacteria and fungi, they might reflect an additional function of HNPs in host defense. The described mechanism links again thrombosis and infection.

An analysis of the link between strokes and soils in the South Carolina coastal plains

The Stroke Belt is a geographical region of the Southeastern United States where resident individuals suffer a disproportionately higher rate of strokes than the rest of the population. While the "buckle" of this Stroke Belt coincides with the Southeastern Coastal Plain region of North and South Carolina and Georgia, there is a paucity of information pinpointing specific causes for this phenomenon. A number of studies posit that an exposure event-potentially microbial in nature-early in life, could be a risk factor. The most likely vector for such an exposure event would be the soils of the Southeastern Coastal Plain region. These soils may have chemical and physical properties which are conducive to the growth and survival of microorganisms which may predispose individuals to stroke. To this aim, we correlated SC stroke mortality data to soil characteristics found in the NRCS SSURGO database. In statewide comparisons, depth to water table (50 to 100 cm, R = 0.62) and soil drainage class (poorly drained, R = 0.59; well drained, R = -0.54) both showed statistically significant relationships with stroke rate. In a 20 county comparison, depth to water table, drainage class, hydric rating (hydric soils, R = 0.56), and pH (very strongly acid, R = 0.66) all showed statistically significant relationships with stroke rate. These data should help direct future research and epidemiology efforts to pinpoint the exact exposure events which predispose individuals to an increased stroke rate.

Outcome of Chlamydia pneumoniae associated acute ischemic stroke in elderly patients: a case-control study

BACKGROUND

Limited data exists about the role of Chlamydia pneumoniae elderly patients with acute ischemic stroke.

OBJECTIVE

To study the role of C. pneumoniae in elderly patients (age more than 65 years) with acute ischemic stroke and its impact on stroke out come.

METHODS

We recruited 100 elderly patients with acute ischemic stroke and 100 age and sex matched controls over a period of 2 years. IgG and IgA anti C. pneumoniae antibodies were measured by microimmunofluorescence technique in patients and controls. Good outcome was defined as a Modified Rankin score (mRS) of ≤2.

RESULTS

We found C. pneumoniae antibodies in 35% stroke patients and in 18% control subjects (p=0.01). Good out come at 90 days follow up was found in 20/35(57.1%) seropositive stroke patients compared to 37/65(56.9%) seronegative stroke patients (p=0.9).

CONCLUSIONS

C. pneumoniae antibody positivity was independently associated with ischemic stroke in elderly patients and its presence does not alter the stroke outcome.

Association of Chlamydia pneumoniae serology and ischemic stroke

BACKGROUND

Stroke is one of the major causes of morbidity and mortality throughout the world. Reports about the role of Chlamydia pneumoniae infection in the development of atherosclerosis have been reported in many studies. The aim of the study was to evaluate the association between Chlamydia pneumoniae infection and ischemic stroke.

METHODS

We evaluated 50 patients with ischemic stroke (32 males and 18 females) and 40 control subjects (22 males and 18 females). They were age- and sex-matched. All enrolled subjects underwent an enzyme-linked immunosorbent assay (ELISA) serologic test for IgG and IgA antibodies for Chlamydia pneumoniae.

RESULTS

Eighteen (36%) patients with ischemic stroke have positive IgA, in comparison with 6 (15%) among the control group (OR 3.18; CI 1.12-9.04; P = 0.03). This translates into the fact that there was a more than three-fold risk of developing ischemic stroke in those with Chlamydia pneumoniae infection compared to those who without. The IgG seropositivity was increased in patients with ischemic stroke, but it did not reach statistical significance (OR = 2.32; CI = 0.97-5.58; P = 0.078).

CONCLUSIONS

Chronic Chlamydia pneumoniae infection demonstrated by positive IgA-type antibody can be considered a significant risk for ischemic stroke.

Chlamydia pneumoniae seropositivity in adults with acute ischemic stroke: A case-control study

BACKGROUND

Causative role of Chlamydia pneumoniae infection in patients with acute ischemic stroke (AIS) remains unresolved till date.

AIM

To investigate the role of C. pneumoniae antibodies in AIS.

MATERIALS AND METHODS

Patients with AIS and sex- and environment-matched controls were enrolled. Antibodies to C. pneumoniae (IgA, IgG and IgM) were measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

A total of 51 patients and 48 controls were enrolled. The IgA seropositivity was significantly associated with AIS (unadjusted odds ratio 3.1; 95% CI 1.38, 6.96; P = 0.005), whereas IgG (unadjusted OR 0.44; 95% CI 0.18, 1.09; P = 0.07) and IgM (unadjusted OR 1.1; 95% CI 0.36, 3.3; P = 0.88) were not. There was no difference in IgA or IgG positivity in different stroke subtypes. On multivariate analysis after adjusting for sex, hypertension, diabetes mellitus, smoking and alcohol, the IgA seropositivity yielded an adjusted OR for stroke (4.72; 95% CI 1.61, 13.83; P = 0.005), while IgG seropositivity did not (OR 0.25; 95% CI 0.08, 0.83; P = 0.23).

CONCLUSIONS

An increased risk of AIS was demonstrated in patients seropositive for C. pneumoniae for IgA antibodies.

Common infections and the risk of stroke

The occurrence of stroke in populations is incompletely explained by traditional vascular risk factors. Data from several case-control studies and one large study using case series methodology indicate that recent infection is a temporarily acting, independent trigger factor for ischemic stroke. Both bacterial and viral infections, particularly respiratory tract infections, contribute to this association. A causal role for infection in stroke is supported by a graded temporal relationship between these conditions, and by multiple pathophysiological pathways linking infection and inflammation, thrombosis, and stroke. Furthermore, observational studies suggest that influenza vaccination confers a preventive effect against stroke. Case-control and prospective studies indicate that chronic infections, such as periodontitis, chronic bronchitis and infection with Helicobacter pylori, Chlamydia pneumoniae or Cytomegalovirus, might increase stroke risk, although considerable variation exists in the results of these studies, and methodological issues regarding serological results remain unresolved. Increasing evidence indicates that the aggregate burden of chronic and/or past infections rather than any one single infectious disease is associated with the risk of stroke. Furthermore, genetic predispositions relating to infection susceptibility and the strength of the inflammatory response seem to co-determine this risk. Here, we summarize and analyze the evidence for common acute and chronic infectious diseases as stroke risk factors.

Chlamydophila pneumoniae Infection and Its Role in Neurological Disorders

Chlamydophila pneumoniae is an intracellular pathogen responsible for a number of different acute and chronic infections. The recent deepening of knowledge on the biology and the use of increasingly more sensitive and specific molecular techniques has allowed demonstration of C. pneumoniae in a large number of persons suffering from different diseases including cardiovascular (atherosclerosis and stroke) and central nervous system (CNS) disorders. Despite this, many important issues remain unanswered with regard to the role that C. pneumoniae may play in initiating atheroma or in the progression of the disease. A growing body of evidence concerns the involvement of this pathogen in chronic neurological disorders and particularly in Alzheimer's disease (AD) and Multiple Sclerosis (MS). Monocytes may traffic C. pneumoniae across the blood-brain-barrier, shed the organism in the CNS and induce neuroinflammation. The demonstration of C. pneumoniae by histopathological, molecular and culture techniques in the late-onset AD dementia has suggested a relationship between CNS infection with C. pneumoniae and the AD neuropathogenesis. In particular subsets of MS patients, C. pneumoniae could induce a chronic persistent brain infection acting as a cofactor in the development of the disease. The role of Chlamydia in the pathogenesis of mental or neurobehavioral disorders including schizophrenia and autism is uncertain and fragmentary and will require further confirmation.

Infectious burden and carotid plaque thickness: the northern Manhattan study

BACKGROUND AND PURPOSE

The overall burden of prior infections may contribute to atherosclerosis and stroke risk. We hypothesized that serological evidence of common infections would be associated with carotid plaque thickness in a multiethnic cohort.

METHODS

Antibody titers to 5 common infectious microorganisms (ie, Chlamydia pneumoniae, Helicobacter pylori, cytomegalovirus, and herpesvirus 1 and 2) were measured among stroke-free community participants and a weighted index of infectious burden was calculated based on Cox models previously derived for the association of each infection with stroke risk. High-resolution carotid duplex Doppler studies were used to assess maximum carotid plaque thickness. Weighted least squares regression was used to measure the association between infectious burden and maximum carotid plaque thickness after adjusting for other risk factors.

RESULTS

Serological results for all 5 infectious organisms were available in 861 participants with maximum carotid plaque thickness measurements available (mean age, 67.2+/-9.6 years). Each individual infection was associated with stroke risk after adjusting for other risk factors. The infectious burden index (n=861) had a mean of 1.00+/-0.35 SD and a median of 1.08. Plaque was present in 52% of participants (mean, 0.90+/-1.04 mm). Infectious burden was associated with maximum carotid plaque thickness (adjusted increase in maximum carotid plaque thickness 0.09 mm; 95% CI, 0.03 to 0.15 mm per SD increase of infectious burden).

CONCLUSIONS

A quantitative weighted index of infectious burden, derived from the magnitude of association of individual infections with stroke, was associated with carotid plaque thickness in this multiethnic cohort. These results lend support to the notion that past or chronic exposure to common infections, perhaps by exacerbating inflammation, contributes to atherosclerosis. Future studies are needed to confirm this hypothesis and to define optimal measures of infectious burden as a vascular risk factor.

Infectious burden and carotid plaque thickness: the northern Manhattan study

BACKGROUND AND PURPOSE

The overall burden of prior infections may contribute to atherosclerosis and stroke risk. We hypothesized that serological evidence of common infections would be associated with carotid plaque thickness in a multiethnic cohort.

METHODS

Antibody titers to 5 common infectious microorganisms (ie, Chlamydia pneumoniae, Helicobacter pylori, cytomegalovirus, and herpesvirus 1 and 2) were measured among stroke-free community participants and a weighted index of infectious burden was calculated based on Cox models previously derived for the association of each infection with stroke risk. High-resolution carotid duplex Doppler studies were used to assess maximum carotid plaque thickness. Weighted least squares regression was used to measure the association between infectious burden and maximum carotid plaque thickness after adjusting for other risk factors.

RESULTS

Serological results for all 5 infectious organisms were available in 861 participants with maximum carotid plaque thickness measurements available (mean age, 67.2+/-9.6 years). Each individual infection was associated with stroke risk after adjusting for other risk factors. The infectious burden index (n=861) had a mean of 1.00+/-0.35 SD and a median of 1.08. Plaque was present in 52% of participants (mean, 0.90+/-1.04 mm). Infectious burden was associated with maximum carotid plaque thickness (adjusted increase in maximum carotid plaque thickness 0.09 mm; 95% CI, 0.03 to 0.15 mm per SD increase of infectious burden).

CONCLUSIONS

A quantitative weighted index of infectious burden, derived from the magnitude of association of individual infections with stroke, was associated with carotid plaque thickness in this multiethnic cohort. These results lend support to the notion that past or chronic exposure to common infections, perhaps by exacerbating inflammation, contributes to atherosclerosis. Future studies are needed to confirm this hypothesis and to define optimal measures of infectious burden as a vascular risk factor.

Seroprevalence of Chlamydia pneumoniae antibodies in stroke in young

BACKGROUND

Younger patients, aged below 45 years, usually lack the conventional risk factors of stroke whereas infections, especially in developing countries, may play a role. There have been many reports in the last decade about the association of Chlamydia pneumoniae (C. pneumoniae) and atherosclerosis involving cerebral vessels.

OBJECTIVE

To investigate the seroprevalence of C. pneumoniae IgG and IgA antibodies in patients aged below 45 years with acute ischemic stroke.

METHODS

This study was done at a tertiary care hospital in South India between January 2004 and December 2006 where we recruited consecutive patients aged less than 45 years with acute ischemic stroke. Age and sex matched controls were recruited from the outpatient department with non stroke diagnosis. All stroke patients underwent CT (Computerized Tomography), MRI (Magnetic Resonance Image), MRA (Magnetic Resonance Angiography), Transthoracic Echocardiography and Carotid Doppler for stroke sub group diagnosis. We measured C. pneumoniae antibodies IgG and IgA by microimmunofluorescence technique in all patients and controls.

RESULTS

A total of 120 patients and 120 controls were studied over a period of two years. We found C. pneumoniae antibodies in 29.1% (35/120) stroke patients and in 12.5% (15/120) control subjects (p=0.002). C. pneumoniae IgG antibodies were found in 27.5 % (33/120) of stroke patients and 12.5% (15/120) of controls (p=0.006). IgA antibodies were observed in 5% (6/120) of strokes and none in control group (p=0.03). After adjustment of all risk factors C. pneumoniae IgG seropositivity showed odds ratio of 2.6; 95% Confidence Interval 1.2-5.6.

CONCLUSIONS

C. pneumoniae IgG antibodies were found to be associated with ischemic stroke in young.

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.

Alzheimer's disease and infection: do infectious agents contribute to progression of Alzheimer's disease?

Infection with several important pathogens could constitute risk factors for cognitive impairment, dementia, and Alzheimer's disease (AD) in particular. This review summarizes the data related to infectious agents that appear to have a relationship with AD. Infections with herpes simplex virus type 1, picornavirus, Borna disease virus, Chlamydia pneumoniae, Helicobacter pylori, and spirochete were reported to contribute to the pathophysiology of AD or to cognitive changes. Based on these reports, it may be hypothesized that central nervous system or systemic infections may contribute to the pathogenesis or pathophysiology of AD, and chronic infection with several pathogens should be considered a risk factor for sporadic AD. If this hypothesis holds true, early intervention against infection may delay or even prevent the future development of AD.

Is Chlamydia pneumoniae seropositivity associated with atherothrombotic cerebrovascular infarction?

BACKGROUND AND OBJECTIVE

Several studies suggested that Chlamydia pneumoniae (CP) infection may be a risk factor for cerebrovascular disease. Since these studies have reported controversial results, we performed this study to identify whether Cp-immunoglobulin was associated with atherothrombotic cerebrovascular infarction (ACI) in Iranian patients.

MATERIALS AND METHODS

Forty-five patients admitted with ACI, and 45 control without ACI were enrolled in this case-control study. Using an enzyme-linked immunosorbed assay kit (ELISA), the presence of CP-immunoglobulin (CP-IgG) in studied patient's sera was determined.

RESULTS

The seroprevalence of CP-IgG was 35(77.7%) in the ACI group (mean age=73.3 years) and 29(64.4%) in the control group (mean age=70.1 years) (P>0.05). There was no difference in sex, age, hypertension, smoking, hyperlipidemia, diabetes and obesity between cases and control groups (P>0.05). No association was observed between CP seropositivity and ACI [OR: 1.95 (95% CI, 0.081-2.03), P=0.16].

CONCLUSION

Our finding suggests that there is no association between ACI and positive CP-IgG in Iranian patients.

The role of infections in the emergence of non-communicable diseases (NCDs): Compelling needs for novel strategies in the developing world

The emergence of non-communicable diseases (NCDs) follows multiple aetiological pathways requiring recognition for effective control and prevention. Infections are proving to be conventional, emerging and re-emerging aetiological factors for many NCDs. This review explores the possible mechanisms by which infections induce NCDs citing examples of studies in Africa and elsewhere where NCDs and infections are proposed or confirmed to be causally linked and also discusses the implications and challenges of these observations for science and medicine. The need to re-evaluate and expand early community and individual preventive and control strategies that will lead to reduction and even elimination of NCDs especially in Africa and other developing countries where infections are prevalent is highlighted.

Association between Chlamydia pneumoniae IgG antibodies and migraine

In this study, there is a confirmed association between cerebral infarction with migraine and Chlamydia pneumoniae infection, but the association between C. pneumoniae IgG antibodies and migraine in the general population has not been investigated. C. pneumoniae IgG antibody levels were compared in 329 adult Chinese patients, who met the International Classification of Headache Disorders 2nd Edition (ICHD II) criteria for migraine, and in 329 healthy subjects. Factors such as gender, age, smoking, consumption of pickle, and body mass index were evaluated. One hundred and ninety-five (59.2%) migraine sufferers and 70 (21.27%) controls were C. pneumoniae IgG antibody-seropositive (P < 0.05). Based on a multivariate stepwise logistic model, the odds’ ratios for C. pneumoniae IgG antibody seropositivity, body mass index, smoking, and consumption of pickle were 3.397 (P = 0.000), 0.858 (P = 0.014), 1.692 (P = 0.012), and 5.469 (P = 0.0000), respectively. In conclusion, C. pneumoniae IgG antibodies may be a risk factor for migraine.

Association between Histoplasma exposure and stroke

BACKGROUND AND PURPOSE

The rate of cerebrovascular events within the stroke belt, a geographic area defined in the Southeastern United States, exceeds that of the rest of the nation. Despite evaluation of multiple risk factors for this disparity, specific causes for the stroke belt have not been elucidated. More than 45 years ago, the US Public Health Service and US Navy cooperative skin-testing program (1958-1965) documented adolescent exposure to Histoplasma capsulatum. Our purpose was to evaluate the association between exposure to Histoplasma capsulatum and subsequent development of stroke.

METHODS

A cross-sectional study of stroke in a cohort of US Navy veterans was designed to assess our hypothesis. Medical records from 23,795 men who participated in the cooperative skin-testing program and who received medical care at Veterans Administration Hospitals and Clinics were reviewed. A logistic regression model was used to estimate the odds ratio of stroke while controlling for multiple covariates. Because of the large number of possible risk factors for stroke, propensity scores were used to reduce bias.

RESULTS

The adjusted odds ratio for stroke in veterans exposed to Histoplasma capsulatum during adolescence was 1.34 (95% confidence interval: 1.1-1.6; P = .0033). The increased risk was independent of traditional cerebrovascular event risk factors. Less frequent risk factors (atrial fibrillation, coronary heart disease, rheumatic heart disease, and prosthetic cardiac valvular replacement) were not controlled in this model.

CONCLUSION

Exposure to Histoplasma capsulatum during adolescence was associated with an increased risk of stroke.

Limited role for C. pneumoniae, CMV and HSV-1 in cerebral large and small vessel atherosclerosis

Aims: To explore whether Chlamydia pneumoniae, Cytomegalovirus and Herpes Simplex Virus type 1 could be detected in large and small cerebral arteries, as well as in an area of brain parenchyma where white matter lesions (leukoaraiosis) can be found, in patients with clinically unmanifested cerebrovascular atherosclerosis. Methods and results( Arterial specimens from the basilar artery and middle cerebral artery, and brain samples from the basal ganglia and periventricular white matter were obtained. Neuropathological changes were assessed in Haematoxylin-Eosin stained sections. Polymerase chain reaction (PCR) was performed on paraffin embedded sections. Subsequently, we performed immunohistochemical staining on samples, which were found positive in PCR. We failed to detect C. pneumoniae, CMV, or HSV-1, in any of the cerebral large vessels. In the brain tissue, we found only one case positive for CMV, and one for C. pneumoniae. Conclusions (our findings suggest a limited role for C. pneumoniae, CMV and HSV-1 in cerebral large and small vessel atherosclerosis.

Chlamydia pneumoniae antibodies in various subtypes of ischemic stroke in Indian patients

BACKGROUND

As infections occur more frequently in developing countries, we carried out this prospective case-control study, to establish the association, if any, between C. pneumoniae antibodies and ischemic stroke particularly in relation to its subtypes.

DESIGN

Antibodies (IgG and IgA) to C. pneumoniae in serum were measured by microimmunofluorescence test in 200 consecutive ischemic stroke patients and 200 age and sex matched controls.

RESULTS

Seventy two out of 200 ischemic stroke patients (36%) had positive C. pneumoniae antibodies (IgG or IgA), compared to 35 out of 200 controls (17.5%) (p<0.0001). IgG antibody was positive in 64/200 (32%) ischemic stroke patients, compared to 34/200(17%) controls (p<0.0001) and IgA was positive in 20/200(10%) ischemic stroke patients compared to 1/200(0.5%) controls (p<0.0001). Logistic regression analysis showed statistically significant association between C. pneumoniae antibody positivity and ischemic stroke, thereby establishing it as an independent risk factor. Prevalence of C. pneumoniae antibodies was significantly higher in all stroke subtypes (except the stroke of undetermined etiology) compared to controls.

CONCLUSION

Significant and independent association was found between C. pneumoniae antibodies and ischemic stroke in this sample of south Indian population. The association was found in all ischemic stroke subtypes, except stroke of undetermined etiology.

Microbial risk factors of cardiovascular and cerebrovascular diseases: potential therapeutical options

Infection and inflammation may have a crucial role in the pathogenesis of atherosclerosis. This hypothesis is supported by an increasing number of reports on the interaction between chronic infection, inflammation, and atherogenesis. Assessment of serological and inflammatory markers of infection may be useful adjuncts in identifying those patients who are at a higher risk of developing vascular events, and in whom more aggressive treatments might be warranted.

Chlamydia pneumoniae and symptomatic carotid atherosclerotic plaque: a prospective study

OBJECTIVE

To investigate the possible link between symptomatic carotid atherosclerotic plaque and Chlamydia pneumoniae.

BACKGROUND

Recently, several studies have demonstrated that there may be a possible link between Chlamydia pneumonia and carotid atherosclerosis, however the real role of Chlamydia pneumoniae is not completely understood.

METHOD

This is a prospective study with a total of 52 patients analyzed. All patients had been submitted to endarterectomy, and had suffered thrombotic ischemic stroke or transient ischemic attack up to 60 days prior to the surgery. Every patient presented carotid stenosis over 70%. The plaque was removed during the surgery and the laboratory exams were immediately done. Evaluation of Chlamydia pneumoniae DNA was done using polymerase chain reaction (PCR).

RESULTS

The PCR analyses of all 52 patients were negative for Chlamydia pneumoniae.

CONCLUSION

These initial results do not show a relationship between Chlamydia pneumoniae and symptomatic carotid atherosclerotic plaque.

Chlamydia pneumoniae aggravates vein graft intimal hyperplasia in a rat model

Background

Along with angioplasty, autologus vein grafts are commonly used for artery bypass grafting in patients with advanced arterial stenosis and drug-resistant angina pectoris. Although initially a successful procedure, long-term functionality is limited due to proliferation and migration of smooth muscle cells. Like in atherosclerosis, common chronic infections caused by viruses and bacteria may contribute to this process of vein graft failure. Here we investigated the possible role of Chlamydia pneumoniae (Cpn) in the pathogenesis of venous graft failure in an experimental animal model. In 2 groups (n = 10 rats/group), an epigastric vein-to-common femoral artery interposition graft was placed. Immediately thereafter, rats were infected with Cpn (5*10⁸ IFU) or injected with control solutions. Rats were sacrificed three weeks after surgery and the grafts were harvested for morphometrical and immunohistochemical analysis.

Results

Cpn administration immediately after vein grafting resulted in a significant increase in medial cross-sectional area, wall thickness and total wall area. There were no significant differences in T-cell or macrophage influx. Likewise, although positive immunostaining for both HSP60 and CRP could be detected, no differences were found between groups. Based on the observation that the number of cells/μm² was also not altered, we conclude that Cpn infection stimulates smooth muscle cell proliferation by hereunto unknown molecular mechanisms, resulting in a significant increase in intimal hyperplasia.

Conclusion

In conclusion, in a well defined animal model we present here for the first time evidence for a role of Chlamydia pneumoniae in the process of venous graft failure.

Chlamydia pneumoniae is a likely risk factor for ischemic stroke in young patients

Recently, Chlamydia pneumoniae has been identified as a risk factor for atherosclerosis, cardiovascular disease, and stroke. In young patients the causes of stroke are more diverse, and remain unknown in about 30% of cases, despite thorough investigations. To find a possible relationship between C. pneumoniae infection and stroke at young age, we investigated C. pneumoniae antibody titers in 41 patients with ischemic stroke who were younger than 50 years old and in 55 healthy control subjects. A positive IgA antibody titer to C. pneumoniae was significantly associated with stroke (crude odds ratio 2.1; 90% confidence interval 1.1-9.5; P = .04). After adjusting for hypertension, smoking, and hypercholesterolemia, positive Chlamydia antibodies remained associated with stroke (adjusted odds ratio 2.8; 90% confidence interval 1.1-7.1; P = .04). No significant association between positive IgG antibodies and stroke was found. Because a positive IgA antibody titer may reflect a persistent infection, these data indicate that persistent C. pneumoniae infection may be an independent risk factor for stroke at young age.

Relationship between periodontal infections and systemic disease

Oral conditions such as gingivitis and chronic periodontitis are found worldwide and are among the most prevalent microbial diseases of mankind. The cause of these common inflammatory conditions is the complex microbiota found as dental plaque, a complex microbial biofilm. Despite 3000 years of history demonstrating the influence of oral status on general health, it is only in recent decades that the association between periodontal diseases and systemic conditions such as coronary heart disease and stroke, and a higher risk of preterm low birth-weight babies, has been realised. Similarly, recognition of the threats posed by periodontal diseases to individuals with chronic diseases such as diabetes, respiratory diseases and osteoporosis is relatively recent. Despite these epidemiological associations, the mechanisms for the various relationships remain unknown. Nevertheless, a number of hypotheses have been postulated, including common susceptibility, systemic inflammation with increased circulating cytokines and mediators, direct infection and cross-reactivity or molecular mimicry between bacterial antigens and self-antigens. With respect to the latter, cross-reactive antibodies and T-cells between self heat-shock proteins (HSPs) and Porphyromonas gingivalis GroEL have been demonstrated in the peripheral blood of patients with atherosclerosis as well as in the atherosclerotic plaques themselves. In addition, P. gingivalis infection has been shown to enhance the development and progression of atherosclerosis in apoE-deficient mice. From these data, it is clear that oral infection may represent a significant risk-factor for systemic diseases, and hence the control of oral disease is essential in the prevention and management of these systemic conditions.

Elevated levels of anti-Chlamydia pneumoniae IgA and IgG antibodies in young adults with ischemic stroke

INTRODUCTION

Data on the role of Chlamydia pneumoniae in patients with ischemic stroke are inconsistent. We investigated the presence of anti-C. pneumoniae antibodies in young adults with ischemic stroke.

METHODS

94 patients (<55 years) with ischemic stroke and 103 controls were enrolled. Indices of anti-C. pneumoniae IgA and IgG were assessed with an ELISA. We determined OR and 95% CI for the IgA and IgG seropositivity in stroke cases.

RESULTS

Mean IgA and IgG indices were higher in stroke patients vs controls (IgA: 1.40 vs 0.56; P < 0.001; IgG: 0.85 vs. 0.78; P < 0.003). The IgA seropositivity was associated with stroke risk (11.92; 5.94-23.92; P < 0.001) as well as IgG seropositivity was (2.31; 1.15-4.61; P < 0.016). Seropositivity assessed with combined IgA and IgG indices was associated with increased stroke risk (OR 9.35; 95% CI 4.78-18.29; P < 0.0001). After controlling for age and sex, the IgA seropositivity yielded a significantly adjusted OR for stroke (8.95; 4.44-18.07; P < 0.002), while IgG seropositivity did not (0.85; 0.53-1.63).

CONCLUSIONS

We find an increased risk of stroke in young patients seropositive to C. pneumoniae in the IgA antibody class. Further studies to explore this finding are warranted.

Chlamydia pneumoniae infection of brain cells: An in vitro study

Inspired by the suggested associations between neurological diseases and infections, we determined the susceptibility of brain cells to Chlamydia pneumoniae (Cpn). Murine astrocyte (C8D1A), neuronal (NB41A3) and microglial (BV-2) cell lines were inoculated with Cpn. Infection was established by immunofluorescence and real-time PCR at various time points. Productive infection was assessed by transferring medium of infected cells to a detection layer. Finally, apoptosis and necrosis post-infection was determined. Our data demonstrate that the neuronal cell line is highly sensitive to Cpn, produces viable progeny and is prone to die after infection by necrosis. Cpn tropism was similar in an astrocyte cell line, apart from the higher production of extracellular Cpn and less pronounced necrosis. In contrast, the microglial cell line is highly resistant to Cpn as the immunohistochemical signs almost completely disappeared after 24 h. Nevertheless, significant Cpn DNA amounts could be detected, suggesting Cpn persistence. Low viable progeny and hardly any necrotic microglial cells were observed. Further research is warranted to determine whether these cell types show the same sensitivity to Cpn in an in vivo setting.

Chlamydia pneumoniae infection is not associated with chronic transplant dysfunction in a rat aortic allograft model

Long-term survival of solid-organ transplants is limited as a result of chronic transplant dysfunction (CTD), which is characterized by occlusion of intragraft vascular tissue due to myointimal hyperplasia. Recent studies have shown a role for infections in vascular pathologies. For example, Chlamydia pneumoniae (Cpn) has been shown to aggravate atherosclerosis, and Cpn immunoglobulin (Ig)G titers correlate with severity of allograft atherosclerosis after cardiac transplantation. In this study, we evaluated the effect of Cpn infection on CTD using a rat aortic allograft model. Orthotopic abdominal aorta transplantations (Tx) were performed with Brown Norway rats as donors and Lewis rats as recipients. Rats were humanely killed at 1 or 8 weeks after surgery. The graft was processed for DNA isolation and histological examination. Influx of macrophages and T cells was assessed using immunohistochemistry. At 1 week after Tx, the perivascular influx of inflammatory cells in the graft was not affected by Cpn infection. Furthermore, only limited numbers of Cpn DNA copies were found in the graft at 1 week after Tx. In addition, Cpn did not alter the severity of myointimal hyperplasia in the rat aortic allograft model at 8 weeks after surgery. Our data suggested that, in the rat aortic allograft model, Cpn infection did not influence the influx of inflammatory cells or the severity of CTD.

Infection as a risk factor for stroke

Persisting disability requiring professional healthcare or help in daily life activities can be expected in a third to a half of all stroke survivors. It is mainly the elderly that are affected. For the increasingly aging population of Western societies, stroke represents an increasing social and economic burden. Besides the existing therapeutic options, additional treatment and prevention strategies are needed. Traditional risk factors do not explain all clinical and epidemiological features of stroke. Recently, the association between infectious and inflammatory processes and the occurrence of vascular disease has been established. This review summarizes the current evidence of infections as stroke risk factors and of potential anti-infective strategies as future methods of stroke prevention.

Chlamydophila (Chlamydia) pneumoniaein the Alzheimer's brain

We assessed the presence and characteristics of the intracellular pathogen Chlamydophila (Chlamydia) pneumoniae in brain-tissue samples from 25 patients with late-onset Alzheimer's disease (AD) and 27 non-AD control individuals. 20/27 AD patients, but only 3/27 controls, were PCR-positive in multiple assays targetting the Cpn1046 and Cpn0695 genes. Culture of the organism from brain-tissue homogenate from one AD patient, and assessment of various chlamydial transcripts in RNA preparations from several patients, demonstrated that the organisms were viable and metabolically active in those samples. Immunohistochemical analyses showed that astrocytes, microglia, and neurons all served as host cells for C. pneumoniae in the AD brain, and that infected cells were found in close proximity to both neuritic senile plaques and neurofibrillary tangles in the AD brain. These observations confirm and significantly extend our earlier study suggesting that this unusual pathogen may play a role in the neuropathogenesis characteristic of AD.

Descripción de inmunógenos de Chlamydia pneumoniae reconocidos por el suero de sujetos con enfermedad arterial periférica

BACKGROUND AND OBJECTIVE

The relationship between antibodies to C. pneumoniae and presence of the bacteria was studied in individuals with peripheral arterial disease.

PATIENTS AND METHOD

An observational analytical, case-control study was performed in 118 patients (68 cases, 50 controls) to investigate immunoglobulin (Ig) G and A against C. pneumoniae in serum, using Western-blot (commercial and no commercial methods), ELISA and MIF; DNA of the bacteria in vascular tissue biopsy specimens was studied by polymerase chain reaction.

RESULTS

Using commercial Western-blot, significant presence of IgG anti-39 kDa and anti-54 kDa was found in cases and was related to MIF results and C. pneumoniae DNA findings; IgA anti-LPS, anti-92 kDa and anti-Hsp60 kDa were also found and related to DNA presence. Using no commercial Western-blot, significant presence of 128.8 and 9.2 kDa bands for IgG was detected in cases and associated with DNA presence; 70.8, 58.9, 47.9, 47.5, 18.4, 12.1, 10.6, 8.1, and 7.6 kDa bands for IgG were found in cases; and DNA was present when 54.6 and 1.1 kDa bands for IgG and 79.4, 50.1, and 18.4 kDa bands for IgA were also detected.

CONCLUSIONS

Using Western-blot, a greater serologic response was found against certain proteins of the bacteria in individuals with peripheral arterial disease. This may reflect an initial stage with presence of DNA and specific IgG. Subsequently, even in absence of the bacteria, an immunomediated disease may develop with presence of IgA and IgG.

A Systematic Comparison of the Quality and Volume of Published Data Available on Novel Risk Factors for Stroke versus Coronary Heart Disease

BACKGROUND

To identify new treatments to prevent stroke, it is important that we have reliable data on potential novel risk factors.

METHODS

We studied seven novel vascular risk factors [apo-lipoprotein (b), C-reactive protein, Chlamydia pneumoniae, fibrin-D dimer, fibrinogen, Helicobacter pylori and lipoprotein (a)] and compared the amount of published data on their relations with ischaemic stroke versus acute coronary events by systematic review of all studies published up to 2003.

RESULTS

From a total of 22,875 abstracts reviewed, 266 eligible studies were identified (167 case-control studies and 99 cohort studies). Two hundred and eleven (79%) studies included coronary events as an outcome for the purpose of a risk factor analysis. In 186 (70%) studies, coronary events were the only outcome that was analysed. Only 73 (27%) studies included stroke or TIA as an outcome event, and only 45 studies (17%) reported risk factor analyses for ischaemic stroke separately. These results were qualitatively consistent across the risk factors studied and the relative lack of data on risk factors for stroke was even greater in prospective cohort studies.

CONCLUSION

Data on novel risk factors for stroke are lacking compared with the equivalent data for acute coronary events, and there are very few data on specific subtypes of ischaemic stroke.

Place of drug therapy in the treatment of carotid stenosis

Carotid stenosis is an important cause of transient ischaemic attacks and stroke. The cause of carotid stenosis is most often atherosclerosis; contributing to the pathogenesis of the lesion are endothelial injury, inflammation, lipid deposition, plaque formation, fibrin, platelets and thrombin. Carotid stenosis accounts for 10-20% of cases of brain infarction, depending on the population studied. Despite successful treatment of selected patients who have had an acute ischaemic stroke with tissue plasminogen activator and the promise of other experimental therapies, prevention remains the best approach to reducing the impact of ischaemic stroke. High-risk or stroke-prone patients can be identified and targeted for specific interventions. At this juncture, treatment of carotid stenosis is a well established therapeutic target and a pillar of stroke prevention. There are two main strategies for the treatment of carotid stenosis. The first approach is to stabilise or halt the progression of the carotid plaque through risk factor modification and medication. Hypertension, diabetes mellitus, smoking, obesity and high cholesterol levels are closely associated with carotid stenosis and stroke; control of these factors may decrease the risk of plaque formation and progression. The second approach is to eliminate or reduce carotid stenosis through carotid endarterectomy or carotid angioplasty and stenting. Carotid endarterectomy, which is the mainstay of therapy for severe carotid stenosis, is beyond the scope of this review. Anticoagulants seem to play little role (if any) in the medical (i.e. non-surgical) treatment of carotid stenosis. Adoption of a healthy lifestyle combined with the reduction of risk factors has been shown to lead to a reduction in the extent of carotid stenosis. The medical treatment of carotid stenosis should be based on the triad of the reduction of risk factors, patient education, and use of antiplatelet agents.

The load of Chlamydia pneumoniae in the Alzheimer's brain varies with APOE genotype

Studies from this laboratory have indicated that the intracellular eubacterial respiratory pathogen Chlamydophila (Chlamydia) pneumoniae is commonly found in brain regions displaying characteristic neuropathology in patients with late-onset Alzheimer's disease (AD) but not in congruent samples from non-AD control individuals. In later work, we provided evidence suggesting that some relationship exists between the APOE epsilon4 gene product and the pathobiology of this organism. In the present report, in situ hybridization analyses indicated that the number of C. pneumoniae-infected cells in affected brain regions of epsilon4-bearing AD patients was higher overall than that in congruent brain regions from AD patients lacking that allele. Quantitative real-time PCR analyses of AD brain tissue samples demonstrated that actual bacterial burden in those samples varied over several orders of magnitude, but that samples from epsilon4-bearing patients did have significantly higher bacterial loads than did congruent samples from patients without the allele (ANOVA, p<0.05). These results may explain in part the observations that epsilon4-bearing individuals have a higher risk of developing AD, and that such patients progress more rapidly to cognitive dysfunction than do individuals lacking this allele.