Antibiotics for myocardial infarction? A possible role of infection in atherogenesis and acute coronary syndromes

Intracranial atherosclerotic disease; current options for surgical or medical treatment

Recently, intracranial atherosclerosis has become a major cause of ischemic stroke, appearing more frequently in Koreans than Caucasians. Symptomatic or asymptomatic intracranial atherosclerosis is a disease that could recur readily even during the treatment with anti-platelet agents. When the symptoms develop, ischemic stroke can not be recovered readily. Therefore, aggressive treatments such as endovascular therapy and bypass surgery are required in addition to medical treatment for the intracranial artery stenosis. Recent intracranial stenting and drug eluting stenting have shown as very advanced effective therapeutic modalities. Nevertheless, until now, a randomized controlled study has not been conducted. Regarding bypass surgery, since the failed EC-IC bypass surgery study performed 20 years ago, extensive studies on its efficacy has not been conducted yet, and thus it has to be performed strictly only in hemodynamically compromised patients. Unless breakthrough drugs that suppress the progression of intracranial atherosclerosis and the formation of thrombi, and facilitate the regression of the arterial stenosis, the treatment concept of the recovery of the blood flow of stenotic arterial territory by mechanical recanalization or bypass surgery would be remained for the prevention as well as treatment of ischemic stroke caused by intracranial atherosclerosis.

Can long-term antibiotic treatment prevent progression of peripheral arterial occlusive disease? A large, randomized, double-blinded, placebo-controlled trial

PURPOSE

The purpose was to investigate in a large, randomized, double-blinded, placebo-controlled trial, whether antibiotic treatment can prevent progression of peripheral arterial disease (PAD).

MATERIAL AND METHODS

Five hundred and seven patients were included; all patients had an established diagnosis of PAD. Their mean age was 66 years (36-85), and 59% were males. Patients were randomized to Roxithromycin 300 mg daily for 28 days. Baseline investigations were ankle blood pressure, ankle-brachial blood pressure index (ABPI), walking distance, C. pneumoniae serology, cholesterol and medical history. Follow-up was performed every 6 months. Primary events were defined as death, peripheral revascularization and major lower limb amputation. Secondary events were thrombosis, stroke, transient cerebral ischaemic attack and myocardial infarction. Change in ABPI was also investigated. Data were analyzed mainly by Cox regression and linear regression.

RESULTS

Included patients with PAD were randomized. Two patients withdrew. Of the remaining, 248 received roxithromycin and 257 placebo. In the treatment group 55% were seropositive and 53% in the placebo group. Mean follow-up was 2.1 years (range 0.06-5.1 years). In the placebo group, 26 died and 80 primary events occurred in total. In the treatment group, 28 died and 74 primary events were observed. The hazard ratio of death was 1.13 (95% CI: 0.68; 1.90), and of primary events 0.92 (95% CI: 0.67; 1.26). Also on secondary events and ABPI changes, no significant differences were found.

CONCLUSION

Long-term treatment with roxithromycin is ineffective in preventing death, amputation, peripheral revascularization, myocardial infarction, stroke, transient cerebral ischaemic attack, thrombosis and decline in ABPI in patients with an established diagnosis of PAD.

Ganoderma lucidum inhibits inducible nitric oxide synthase expression in macrophages

Nitric oxide (NO) is a principal mediator in many physiological and pathological processes. Overproduction of NO via the inducible nitric oxide synthase (iNOS) has cytotoxic effect through the formation of peroxynitrite with superoxide anion. The iNOS is mainly expressed in macrophages and is able to produce large amount of NO. The expression of iNOS is mainly regulated at the transcriptional level. The iNOS-mediated NO production plays a role in the development of atherosclerosis. Ganoderma lucidum (G. lucidum, Linzhi or Reishi) is a traditional herbal medicine which is commonly used as health supplement. Several studies have demonstrated its effectiveness against cancer, immunological disorders and cardiovascular diseases. The objective of the present study was to investigate the effect of G. lucidum on iNOS-mediated NO production in macrophages. Human monocytic cell (THP-1) derived macrophages were incubated with lipopolysaccharide (LPS) for 24 h. Such treatment significantly stimulated NO production (253% versus the control). Such a stimulatory effect was resulted from increased iNOS mRNA expression (270% versus the control) and iNOS activity (169.5% versus the control) in macrophages. The superoxide anion level was also elevated (150% versus the control) in LPS-treated macrophages. Treatment of macrophages with G. lucidum extract (100 microg/ml) completely abolished LPS-induced iNOS mRNA expression and NO production. Such an inhibitory effect of G. lucidum was mediated via its antioxidant action against LPS-induced superoxide anion generation in macrophages. These results suggest that G. lucidum may exert a therapeutic effect against atherosclerosis via ameliorating iNOS-mediated NO overproduction in macrophages.

Progression of peripheral arterial occlusive disease is associated with Chlamydia pneumoniae seropositivity and can be inhibited by antibiotic treatment

A possible influence of Chlamydia pneumoniae seropositivity on the clinical course of peripheral arterial occlusive disease (PAOD) has not been investigated previously. Though roxithromycin therapy was found to inhibit progression of PAOD, the nature of this effect (antibiotic or anti-inflammatory) has remained elusive. The course of PAOD was prospectively assessed in elderly men during 4 years, comparing 51 C. pneumoniae seropositive (IgG>/=1:128) with 46 seronegative patients (IgG<1:64 and IgA<1:32). Twenty of the seropositive patients were treated with roxithromycin (400 mg daily) for 4 weeks. Limitation of the walking distance to 200 m or less was observed in 55% of the seropositive untreated patients as compared to 30% of both, seronegative and macrolide-treated patients. The number of invasive revascularizations per patient was 1.7 in the seropositive untreated group as compared to 0.5 in the seronegative and the macrolide-treated group. Considering possible confounding variables, such as classical vascular risk factors, ordinal regression analyses showed a significant association of C. pneumoniae seropositivity with limitation of the walking distance (p=0.027) and need for invasive revascularization (p=0.037). The effect of macrolide treatment on these outcome measures was marked (p<0.001 and p=0.040, respectively) during 2.7 years but decreased in the second part of the observation period. This study provides good evidence that C. pneumoniae are involved in the progression of PAOD and that antibiotic treatment directed against C. pneumoniae is effective in inhibiting this process.

High prevalence of Chlamydia pneumoniae seropositivity in Mexican patients with ischemic heart disease

BACKGROUND

Risk factors for development of atherosclerosis, such as hyperlipidemia, high blood pressure, smoking habit, and diabetes mellitus, have been identified. The possibility that infectious agents may unchain biological and biochemical reactions related to inflammation, atherogenesis, and vascular thromboses events have recently been described. Chlamydia pneumoniae has been associated with coronary artery disease in some seroepidemiology studies. Reports of this association are limited in the Latin American population; therefore, we conducted a case-control study to explore this issue in the Mexican population.

METHODS

Eighty nine patients with scintigraphic evidence of coronary artery disease compared with a control group of 105 individuals were analyzed. Serum levels of IgA, IgM, and IgG against Chlamydia pneumoniae were determined using enzyme immunoassay method in all subjects. Conventional risk factors were also analyzed.

RESULTS

High seroprevalence of IgA and IgG with no significant difference between the two groups was found. Prevalence of antibodies was as follows: IgA 56.2% (50/89 patients); IgG 66.3% (59/ 89 patients) in coronary artery disease group; IgA 56.2% (59/105 patients), and IgG 70.5% (74/105 patients) in control group. Among common risk factors for coronary artery disease, significant differences were found in males, in patients with diabetes, and in habitual smokers.

CONCLUSIONS

These results suggest a high prevalence of C. pneumoniae infection in the studied population. However, in this series seroprevalence was not evidently associated with coronary artery disease (CAD). To clarify the possible relation between C. pneumoniae and coronary atherosclerosis, additional studies must be performed.

Chlamydia pneumoniae infection related atherosclerotic clinical variables on carotid stenosis

OBJECTIVE

Research results showed that Chlamydia pneumoniae infection is related to atherosclerosis. C. pneumoniae infection may exacerbate atherogenesis. We investigated the presence of this microorganism for patients who underwent carotid endarterectomy and evaluated clinical values of C. pneumoniae infection on carotid stenosis.

METHODS

Twenty patients with carotid stenosis were enrolled in this prospective study between 1997 and 1999. The patients were observed on whether they were positive or negative in four C. pneumoniae measures, namely; IgA titers, IgG titers, presence of electron microscopy, and immunocytochemistry in the endarterectomy specimens. Possible clinical findings for atherosclerosis were also observed of Chlamydial measures such as the percentage of carotid stenosis, cholesterol and triglyceride levels, smoking status, symptomatic or non-transient ischaemic attack or stroke, previous ischaemic event, calcification at surgery, ulceration on angiographies, ulceration at surgery and hypertension were included in this evaluation.

RESULTS

Specific C. pneumoniae IgG were detected as positive in 9 (45%) of 20 patient samples. These patients were regarded as having chronic Chlamydia pneumoniae infection. None of the patients were positive for IgA antibody. This result demonstrated no evidence of reinfection. Immunocytochemistry and electron microscopy were positive in 7 (35%) of the 20 patients and correlated with positive serological results. The proportion of previous ischaemic events, calcification at surgery, ulceration on angiography, and ulceration at surgery were found significantly higher ( p < 0.05 ) for patients who are positive for chlamydial measures than those who are negative.

CONCLUSION

The results of this study demonstrated an association between C. pneumoniae to atherosclerosis. The proportion of patients who are positive for Chlamydia measures (IgG titers, electron microscopy, and immunocytochemistry) is significantly higher for those who were positive for each of these clinical variables (PIE, CALCI, U1, and U2) than who were negative. We emphasise, the higher incidence in clinical variables of PIE, CALCI, U1, and U2 in Chlamydia measures positive group may support the association of C. pneumoniae with atherosclerotic events.

Effects of heavy alcohol consumption on the cardiovascular system may be mediated in part by the influence of alcohol-induced depression on the immune system

The harmful effects of heavy alcohol use are well-documented and wide-ranging. Heavy drinking may cause or exacerbate cardiovascular disorders. The author suggests that effects of heavy alcohol consumption on the cardiovascular system may be mediated in part by the influence of alcohol-induced depression on the immune system. This hypothesis is based on the following data: (1) alcohol misuse may cause or exacerbate depression; (2) depressive disorders are associated with increased incidence, morbidity, and mortality of cardiovascular disorders; (3) the immune system may mediate effects of depressive disorders on the cardiovascular system. Further studies are needed to clarify the etiopathogenesis of alcohol-related disorders and develop new treatment modalities.

Role of antibiotics for the prevention of cardiovascular disease

OBJECTIVE

To evaluate the data regarding the use of antibiotic therapy for the prevention of cardiovascular events.

DATA SOURCES

Pertinent literature was identified through a MEDLINE search (1966-September 2001) and through other secondary literature databases and/or bibliographies of pertinent articles.

DATA SYNTHESIS

Cardiovascular disease is a common cause of morbidity and mortality among the general population, with well-defined risk factors (e.g., diabetes, hypertension, hyperlipidemia, cigarette smoking, genetic predisposition). Clinical data evaluating the association between the aforementioned risk factors and the development of atherosclerosis and subsequent cardiovascular disease are substantial; however, these risk factors may only partially explain the high prevalence of cardiovascular disease. The presence of Chlamydia pneumoniae within atherosclerotic lesions has been documented and may be an additional risk factor for the development and progression of cardiovascular disease.

CONCLUSIONS

The results of primary and secondary prevention trials have shown conflicting evidence with regard to the beneficial effects of antibiotic therapy to reduce cardiovascular events. Currently, the lack of certainty in published data does not support the use of antibiotics for the prevention of cardiovascular disease. Clinicians should continue to emphasize interventions proven to reduce adverse cardiovascular events such as smoking cessation, reduction of hyperlipidemia, and control of hypertension.

Role of infection in atherosclerosis and coronary artery disease: a new therapeutic target?

There is growing evidence that inflammatory processes may be involved in the development of atherosclerosis and its complications. Viral and bacterial pathogens have been implicated as possible causative factors in the pathogenesis of coronary artery disease and postangioplasty restenosis. Antibiotic trials have been completed examining which treatment of infection can prevent the complications of coronary artery disease. In high-risk patients, the results of these most recent studies have not revealed any benefit of treatment.

Changes in proinflammatory cytokine activity after menopause

There is now a large body of evidence suggesting that the decline in ovarian function with menopause is associated with spontaneous increases in proinflammatory cytokines. The cytokines that have obtained the most attention are IL-1, IL-6, and TNF-alpha. The exact mechanisms by which estrogen interferes with cytokine activity are still incompletely known but may potentially include interactions of the ER with other transcription factors, modulation of nitric oxide activity, antioxidative effects, plasma membrane actions, and changes in immune cell function. Experimental and clinical studies strongly support a link between the increased state of proinflammatory cytokine activity and postmenopausal bone loss. Preliminary evidence suggests that these changes also might be relevant to vascular homeostasis and the development of atherosclerosis. Better knowledge of the mechanisms and the time course of these interactions may open new avenues for the prevention and treatment of some of the most prevalent and important disorders in postmenopausal women.

Chlamydia pneumoniae and atherosclerosis -- what we know and what we don't

The clinical manifestations of atherosclerosis include coronary artery disease (CAD), stroke, abdominal aortic aneurysm and peripheral vascular disease. World-wide, CAD and stroke are the leading causes of death and disability. The recognition of atherosclerosis as an inflammatory disease in its genesis, progression and ultimate clinical manifestations has created an interesting area of vascular research. Apart from those well-known traditional risk factors for atherosclerosis, novel and potentially treatable atherosclerotic risk factors such as homocysteine (an amino acid derived from the metabolism of dietary methionine that induces vascular endothelial dysfunction) and infections have emerged. In fact, the century-old 'infectious' hypothesis of atherosclerosis has implicated a number of micro-organisms that may act as contributing inflammatory stimuli. Although cytomegalovirus, Helicobacter pylori and Chlamydia pneumoniae are the three micro-organisms most extensively studied, this review will focus on C. pneumoniae. Collaborative efforts from many disciplines have resulted in the accumulation of evidence from seroepidemiological, pathological, animal model, immunological and antibiotic intervention studies, linking C. pneumoniae with atherosclerosis. Seroepidemiological observations provide circumstantial evidence, which is weak in most prospective studies. Pathological studies have demonstrated the preferential existence of C. pneumoniae in atherosclerotic plaque tissues, while animal model experiments have shown the induction of atherosclerosis by C. pneumoniae. Finally, immunological processes whereby C. pneumoniae could participate in key atherogenic and atherothrombotic events have also been identified. Although benefits of the secondary prevention of atherosclerosis have been demonstrated in some antibiotic intervention studies, a number of negative studies have also emerged. The results of the ongoing large prospective human antibiotic intervention trials may help to finally establish if there is a causal link between C. pneumoniae infection and atherosclerosis.

Absence of Chlamydia pneumoniae in surgical specimens of coronary and carotid arteries by polymerase chain reaction

PURPOSE

Several recent articles indicate the renewed interest that Chlamydia pneumoniae is associated with and contributes to arterial diseases. Associations have been established for coronary arteries, carotid arteries and abdominal aortic aneurysms by serological studies, immunofluorescence and DNA-specific testing. The purpose of this study was to determine the presence of C. pneumoniae in coronary artery plaques, carotid artery plaques and old vein grafts that were harvested at the time of surgery.

METHODS AND MATERIALS

Interventions were carried out on patients with carotid artery disease and coronary disease based upon their anatomic findings and symptomatology. Plaques were removed from the carotid arteries with standard endarterectomy techniques. The coronary plaques were removed utilizing blunt dissection to peel the plaque from the coronary artery. Old vein grafts were harvested during repeat surgery by excising the vein grafts. The tissue specimens were analyzed by polymerase chain reaction (PCR).

RESULTS

Ninety-nine specimens from 68 consecutive patients with advanced coronary atherosclerosis with or without cerebrovascular disease were analyzed. We failed to find C. pneumoniae in any of the vascular tissue.

CONCLUSIONS

A large cooperative study involving surgical specimen analysis is needed to assess the role of C. pneumoniae in the etiology of atherosclerosis.

Near 10-year and longer periods modulate circadians: intersecting anti-aging and chronoastrobiological research

Biological cycles with relatively long and some unusual periods in the range of the half-week, the half-year, years, or decades are being discovered. Their prior neglect constituted a confounder in aging and much other research, which then"flew blind" concerning the uncertainties associated with these cycles when they are not assessed. The resolution of more about 10-year and other cycles, some reported herein, replaces the admission of complete unpredictability, implied by using the label "secularity." Heretofore unaccounted-for variability becomes predictable insofar as it proves to be rhythmic and is mapped systematically to serve as a battery of useful reference values. About 10-year cycles in urinary 17-ketosteroid excretion and in heart rate and its variability, among others, are aligned with cycles of similar length in mortality from myocardial infarction. Associations accumulate between cycles of natural physical time structures, chronomes such as the 10.5-year (circadecennian) Schwabe and the 21-year (circavigintunennian) Hale cycles of solar activity, and chronomes in biota. There are about 50-year (circasemicentennian) cycles in mortality from stroke in Minnesota and in the Czech Republic and also in human morphology at birth, the latter result reducing the likelihood that these cycles are purely human made. Associations among large populations warrant long-term systematic coordinated sampling of natural physical and biological variables of interest for the design of countermeasures against already documented elevated risks of stroke, myocardial infarction, and other catastrophic diseases, notably in elderly adults. New findings will be introduced against the background of the documented value of mapping rhythms in medicine and gerontology. In both these fields, rhythms promise the seeming paradox of better care for less.

Feedsidewards: intermodulation (strictly) among time structures, chronomes, in and around us, and cosmo-vasculo-neuroimmunity. About ten-yearly changes: what Galileo missed and Schwabe found

The spectrum of biological rhythms is extended far beyond circadians, circannuals, and ultradians, such as 1.5-hourly melatonin and 8-hourly endothelin-1 (ET-1) rhythms by statistics of natality, growth, morbidity, and mortality, some covering decades or centuries on millions of individuals. These reveal infradian cycles to be aligned with half-weekly rhythms in ET-1, weekly and half-yearly ones in melatonin, and even longer--about 50-, about 20-, and about 10-year cycles found in birth statistics. About daily, weekly, yearly, and ten-yearly patterns are also found in mortality from myocardial infarctions; the 10-yearly ones are also in heart rate and its variability; in steroid excretion, an aspect of resistance, for example, to bacteria; and in the genetic changes of the bacteria themselves. Automatic physiological measurements cover years and, in one case, cover a decade; the latter reveal an about 10-year (circadecennial) cycle. ECGs, covering months beat-to-beat, reveal circaseptans, gaining prominence in response to magnetic storms or after coronary artery bypass grafting. A spectrum including cycles from fractions of 1 Hz to circasemicentennians is just one element in biological time structures, chronomes. Chaos, trends, and any unresolved variability are the second to fourth elements of chronomes. Intermodulations, feedsidewards, account for rhythmically and thus predictably recurring quantitive differences and even for opposite treatment effects of the same total dose(s) of (1) immunomodulators inhibiting or stimulating DNA labeling of bone in health or speeding up versus slowing down a malignant growth and thus shortening or lengthening survival time, or (2) raising or lowering blood pressure or heart rate in the vascular aspect of the body's defense. Latitude-dependent competing photic and nonphotic solar effects upon the pineal are gauged by alternating yearly (by daylight) and half-yearly (by night) signatures of circulating melatonin at middle latitudes and by half-yearly signatures at noon near the pole. These many (including novel near 10-yearly) changes, for example, in 17-ketosteroid excretion, heart rate, heart rate variability, and myocardial infarction in us and those galactic, solar, and geophysical ones around us have their own special signatures and contribute to a cosmo-vasculo-immunity and, if that fails, to a cosmo(immuno?) pathology.

Inflammation, infection and antimicrobial therapy in coronary heart disease--where do we currently stand?

Traditional atherosclerotic risk factors such as hypertension, smoking, hyperlipidaemia and diabetes mellitus, account for only about 50% of the clinical occurrence of coronary heart disease (CHD). The infectious hypothesis proposes that various microorganisms, in particular, Chlamydia pneumoniae, may serve as potential etiological factors, linking inflammation and atherosclerosis (or its clinical manifestations). Evidence from seroepidemiology, pathology, animal models, molecular biology and immunology, and human antibiotic intervention studies, collectively have suggested a largely positive association between C. pneumoniae infection and CHD. As CHD is a multifactorial disease, it is possible that C. pneumoniae may interact with conventional cardiovascular risk factors and predispose certain genetically susceptible people to atherosclerotic disease. However, the precise nature of a causal or coincidental link between C. pneumoniae and CHD remains to be determined. The results of ongoing antibiotic intervention studies may help to further clarify the role of infection and inflammation in CHD, but until such a role is proven beyond reasonable doubt, antimicrobial therapy cannot yet be justified in the treatment or prevention of CHD. A current perspective is presented in this review.

The association of infection and coronary artery disease: an update

Numerous studies have reported an association of coronary atherosclerosis and restenosis with certain bacterial and viral infections. This article reviews the pathophysiology of atherosclerosis, the role of infectious agents (cytomegalovirus, Chlamydia pneumoniae and Helicobacter pylori) in atherogenesis and studies supporting the potential beneficial effects of antibiotics or antiviral agents in the management of atherosclerotic disease. The interactions of cytomegalovirus and the arterial wall have been extensively studied. However, despite the successful preliminary therapeutic trials with the use of macrolides in augmenting possible C. pneumoniae-induced cardiovascular events, the exact mechanisms of how C. pneumoniae enters the arterial wall remains unknown at this point. For H. pylori, regardless of the large number of studies performed to assess the association between H. pylori and coronary artery disease, no definitive conclusion could be made at this time, due to contradictory results. Before one can widely adopt the use of antibiotics or antiviral agents as treatment for atherosclerosis, further studies must be designed to address some important issues. In vivo animal models need to be established to further examine the various hypotheses regarding the interaction of infectious agents and atherosclerosis and restenosis. Large-scale prospective cohort studies should be designed to relate evidence of infection to future risk of cardiovascular diseases. Confounding variables, such as other cardiovascular risk factors and socio-economic status, should be controlled in order to strengthen the association. Further interventional studies are also required to establish the best antibiotic or antiviral regimen to maximise efficacy and minimise side effects.

Identification of periodontal pathogens in atheromatous plaques

BACKGROUND

Recent studies suggest that chronic infections including those associated with periodontitis increase the risk for coronary vascular disease (CVD) and stroke. We hypothesize that oral microorganisms including periodontal bacterial pathogens enter the blood stream during transient bacteremias where they may play a role in the development and progression of atherosclerosis leading to CVD.

METHODS

To test this hypothesis, 50 human specimens obtained during carotid endarterectomy were examined for the presence of Chlamydia pneumoniae, human cytomegalovirus, and bacterial 16S ribosomal RNA using specific oligonucleotide primers in polymerase chain reaction (PCR) assays. Approximately 100 ng of chromosomal DNA was extracted from each specimen and then amplified using standard conditions (30 cycles of 30 seconds at 95 degrees C, 30 seconds at 55 degrees C, and 30 seconds at 72 degrees C). Bacterial 16S rDNA was amplified using 2 synthetic oligonucleotide primers specific for eubacteria. The PCR product generated with the eubacterial primers was transferred to a charged nylon membrane and probed with digoxigenin-labeled synthetic oligonucleotides specific for Actinobacillus actinomycetemcomitans, Bacteroides forsythus, Porphyromonas gingivalis, and Prevotella intermedia.

RESULTS

Eighty percent of the 50 endarterectomy specimens were positive in 1 or more of the PCR assays. Thirty-eight percent were positive for HCMV and 18% percent were positive for C. pneumoniae. PCR assays for bacterial 16S rDNA also indicated the presence of bacteria in 72% of the surgical specimens. Subsequent hybridization of the bacterial 16S rDNA positive specimens with species-specific oligonucleotide probes revealed that 44% of the 50 atheromas were positive for at least one of the target periodontal pathogens. Thirty percent of the surgical specimens were positive for B. forsythus, 26% were positive for P. gingivalis, 18% were positive for A. actinomycetemcomitans, and 14% were positive for P. intermedia. In the surgical specimens positive for periodontal pathogens, more than 1 species was most often detected. Thirteen (59%) of the 22 periodontal pathogen-positive surgical specimens were positive for 2 or more of the target species.

CONCLUSIONS

Periodontal pathogens are present in atherosclerotic plaques where, like other infectious microorganisms such as C. pneumoniae, they may play a role in the development and progression of atherosclerosis leading to coronary vascular disease and other clinical sequelae.