Alireza Shamaei-Tousi

Socioeconomic status, pathogen burden and cardiovascular disease risk

Objective: Socioeconomic status (SES) is inversely associated with coronary heart disease (CHD) risk. Cumulative pathogen burden may also predict future CHD. The hypothesis was tested that lower SES is associated with a greater pathogen burden, and that pathogen burden accounts in part for SES differences in cardiovascular risk factors. Methods: This was a cross-sectional observational study involving the clinical examination of 451 men and women aged 51–72 without CHD, recruited from the Whitehall II epidemiological cohort. SES was defined by grade of employment, and pathogen burden by summing positive serostatus for Chlamydia pneumoniae, cytomegalovirus and herpes simplex virus 1. Cardiovascular risk factors were also assessed. Results: Pathogen burden averaged 1.94 (SD) 0.93 in the lower grade group, compared with 1.64 (0.97) and 1.64 (0.93) in the intermediate and higher grade groups (p = 0.011). Pathogen burden was associated with a higher body mass index, waist/hip ratio, blood pressure and incidence of diabetes. There were SES differences in waist/hip ratio, high-density lipoprotein-cholesterol, fasting glucose, glycated haemoglobin, lung function, smoking and diabetes. The SES gradient in these cardiovascular risk factors was unchanged when pathogen burden was taken into account statistically. Conclusions: Although serological signs of infection with common pathogens are more frequent in lower SES groups, their distribution across the social gradient does not match the linear increases in CHD risk present across higher, intermediate and lower SES groups. Additionally, pathogen burden does not appear to mediate SES differences in cardiovascular risk profiles.

Delayed invasion of the kidney and brain by Borrelia crocidurae in plasminogen-deficient mice

ABSTRACT Borrelia crocidurae is an etiologic agent of relapsing fever in Africa and is transmitted to humans by the bite of soft ticks of the genus Ornithodoros. The role of the plasminogen (Plg) activation system for the pathogenicity of B. crocidurae was investigated by infection of Plg-deficient (plg−/−) and Plg wild-type (plg+/+) mice. No differences in spirochetemia were observed between the plg−/− andplg+/+ mice. However, signs indicative of brain invasion, such as neurological symptoms and/or histopathological changes, were more common in plg+/+ mice. Quantitative immunohistochemical analysis demonstrated infection of spirochetes in kidney interstitium and brain as soon as 2 days postinoculation. Lower numbers of extravascular spirochetes inplg−/− mice during the first days of infection suggested a less efficient invasion mechanism in these mice than in the plg+/+ mice. The invasion of the kidneys in plg−/− mice produced no significant inflammation, as seen by quantitative immunohistochemistry of the CD45 common leukocyte marker. However, significant kidney inflammation was observed with infection in theplg+/+ mice. In brain, inflammation was more severe in plg+/+ mice than inplg−/− mice, and the numbers of CD45+ cells increased significantly with duration of infection in the plg+/+ mice. The results show that invasion of brain and kidney occurs as early as 2 days after inoculation. Also, Plg is not required for establishment of spirochetemia by the organism, whereas it is involved in the invasion of organs.

Plasma heat shock protein 60 and cardiovascular disease risk: the role of psychosocial, genetic, and biological factors

Abstract The Whitehall Study is a prospective epidemiological study of cardiovascular risk factors in healthy members of the British Civil Service, which has identified psychological distress as a major risk factor for coronary heart disease. The levels of circulating Hsp60 in 860 participants from the Whitehall cohort and 761 individuals diagnosed with diabetes have been measured and related to psychological, biological, and genetic factors. In the Whitehall participants, concentrations of Hsp60 ranged from undetectable to mg/mL levels. Circulating Hsp60 correlated with total and low-density lipoprotein (LDL) cholesterol and was positively associated with a flattened slope of cortisol decline over the day. Levels of this stress protein also correlated with measures of psychological stress including psychological distress, job demand, and low emotional support. Mass spectrometric analysis of circulating immunoreactive Hsp60 reveal that it is predominantly the intact protein with no mitochondrial import peptide, suggesting that this circulating protein emanates from mitochondria. The Hsp60 is stable when added to plasma and the levels in the circulation of individuals are remarkably constant over a 4-year period, suggesting plasma levels are partly genetically controlled. Sequence analysis of the HSP60-HSP10 intergenic promoter region identified a common variant 3175 C>G where the G allele had a frequency of 0.30 and was associated with higher Hsp60 levels in 761 type 2 diabetic patients. The extended range of plasma Hsp60 concentrations in the general population is genuine and is likely to be related to genetic, biological, and psychosocial risk factors for coronary artery disease.

A New Approach for the Discovery of Antibiotics by Targeting Non-Multiplying Bacteria: A Novel Topical Antibiotic for Staphylococcal Infections

In a clinical infection, multiplying and non-multiplying bacteria co-exist. Antibiotics kill multiplying bacteria, but they are very inefficient at killing non-multipliers which leads to slow or partial death of the total target population of microbes in an infected tissue. This prolongs the duration of therapy, increases the emergence of resistance and so contributes to the short life span of antibiotics after they reach the market. Targeting non-multiplying bacteria from the onset of an antibiotic development program is a new concept. This paper describes the proof of principle for this concept, which has resulted in the development of the first antibiotic using this approach. The antibiotic, called HT61, is a small quinolone-derived compound with a molecular mass of about 400 Daltons, and is active against non-multiplying bacteria, including methicillin sensitive and resistant, as well as Panton-Valentine leukocidin-carrying Staphylococcus aureus. It also kills mupirocin resistant MRSA. The mechanism of action of the drug is depolarisation of the cell membrane and destruction of the cell wall. The speed of kill is within two hours. In comparison to the conventional antibiotics, HT61 kills non-multiplying cells more effectively, 6 logs versus less than one log for major marketed antibiotics. HT61 kills methicillin sensitive and resistant S. aureus in the murine skin bacterial colonization and infection models. No resistant phenotype was produced during 50 serial cultures over a one year period. The antibiotic caused no adverse affects after application to the skin of minipigs. Targeting non-multiplying bacteria using this method should be able to yield many new classes of antibiotic. These antibiotics may be able to reduce the rate of emergence of resistance, shorten the duration of therapy, and reduce relapse rates.

Whole-Body Imaging of Sequestration of Plasmodium falciparum in the Rat

ABSTRACT The occlusion of vessels by packed Plasmodium falciparum-infected (iRBC) and uninfected erythrocytes is a characteristic postmortem finding in the microvasculature of patients with severe malaria. Here we have employed immunocompetent Sprague-Dawley rats to establish sequestration in vivo. Human iRBC cultivated in vitro and purified in a single step over a magnet were labeled with 99mtechnetium, injected into the tail vein of the rat, and monitored dynamically for adhesion in the microvasculature using whole-body imaging or imaging of the lungs subsequent to surgical removal. iRBC of different lines and clones sequester avidly in vivo while uninfected erythrocytes did not. Histological examination revealed that a multiadhesive parasite adhered in the larger microvasculature, inducing extensive intravascular changes while CD36- and chondroitin sulfate A-specific parasites predominantly sequester in capillaries, inducing no or minor pathology. Removal of the adhesive ligand Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), preincubation of the iRBC with sera to PfEMP1 or preincubation with soluble PfEMP1-receptors prior to injection significantly reduced the sequestration. The specificity of iRBC binding to the heterologous murine receptors was confirmed in vitro, using primary rat lung endothelial cells and rat lung cryosections. In offering flow dynamics, nonmanipulated endothelial cells, and an intact immune system, we believe this syngeneic animal model to be an important complement to existing in vitro systems for the screening of vaccines and adjunct therapies aiming at the prevention and treatment of severe malaria.

Differential Regulation of Circulating Levels of Molecular Chaperones in Patients Undergoing Treatment for Periodontal Disease

Background Evidence is emerging that molecular chaperones, in addition to their intracellular protein folding actions, can act as intercellular signaling proteins with an ability to modulate leukocyte function. Recent evidence has also shown that these proteins can exist in the circulation and may be involved in disease pathogenesis. We have used periodontitis and its treatment as a model of inflammation in the human to determine its effects on levels of circulating HSP10, HSP60 and BiP. Methodology/Principal Findings A group of periodontal patients and matched controls were examined at the beginning of the study and then at 1 day and 6 months following periodontal or control therapy. Plasma levels of HSP10, HSP60 and BiP were measured by immunoassay and related to other plasma measures of inflammation. Periodontal patients had significantly less circulating levels of HSP10 or BiP compared with the controls. In contrast, more periodontal patients had intermediate levels of HSP60. Treatment of the periodontitis caused an increase in plasma levels of HSP10 although it had no effect on BiP. Treatment had no influence of HSP60 levels. Plasma HSP10 levels after therapy correlated with markers of periodontal clinical improvement. Conclusions/Significance Circulating levels of molecular chaperones are influenced by local inflammation. HSP10 is known to be an anti-inflammatory factor. The marked decrease of this circulating protein in active inflammation and its recovery post-treatment suggests that it may have a role in controlling periodontal inflammation.

The relationship between carotid stiffness and circulating levels of heat shock protein 60 in middle-aged men and women

Objective There is growing evidence that the presence of the cell stress protein heat shock protein (HSP) 60 in the circulation is associated with risk of coronary heart disease. In this study, we measured the association between plasma HSP60 and carotid arterial stiffness in middle-aged men and women. Methods Six hundred and forty-seven men and women aged 50–72 years and free of cardiovascular disease and medication were tested. Carotid artery distensibility coefficient was assessed ultrasonically as a measure of arterial stiffness, and plasma HSP60 was assessed using a sensitive immunoassay. Results We found a significant, independent association between high plasma levels of HSP60 and increased carotid stiffness. Carotid distensibility coefficient was also related to diabetes, adiposity, blood pressure, lipids, plasma interleukin-6 and C-reactive protein. After adjusting for these factors, the odds of HSP60 concentration of at least 1000 ng/ml were 1.79 (95% confidence intervals 1.06–3.04) for participants in the lowest compared with the highest tertile of the distensibility coefficient. Conclusion HSP60 is a potent activator of vascular endothelial cells and smooth muscle cells. Thus, it is possible that long-term stimulation of these cell populations by blood-borne HSP60 acts to drive blood vessel changes resulting in decreased arterial elasticity.

Protective effect of human heat shock protein 60 suggested by its association with decreased seropositivity to pathogens.

ABSTRACT The presence of heat shock protein 60 (Hsp60) in human plasma has been linked with cardiovascular disease (CVD). In this study, the examination of the relationship between Hsp60 in plasma and seropositivity for three microbial agents, which are thought to be risk factors for CVD, surprisingly revealed a negative association between Hsp60 and seropositivity, suggesting a protective effect of this circulating stress protein.

Molecular Chaperones and Cell Signalling: Molecular Chaperones: The Unorthodox View

© Cambridge University Press 2005. Introduction Like a Brian Rix farce, in which the characters’ identities are continuously changing, the functions of the class of protein known as molecular chaperones has been unfolding continuously over the past decade resulting in substantial confusion. However, like such farces, we are confident that the denouement will be a complete surprise and will provide a new world picture of the processes with which molecular chaperones are involved. This short chapter aims to introduce the reader to the rapidly changing world of molecular chaperones as an aid to the reading of the rest of the chapters in this volume. Molecular chaperones are protein folders Our story starts with a huff and a puff with the study of the response of the polytene chromosomes of Drosophila to various stressors. This revealed novel patterns of specific chromosomal puffs, in response to heat, and a variety of other environmental stresses, representing the transcription of selected genes [1, 2]. The behaviour of cells exposed to various stresses became known as the heat shock response or the cell stress response and we now appreciate the very large number of environmental factors to which cells will respond in this stereotypical manner. The ‘molecularisation’ of the cell stress response occurred in the late 1980s with the pioneering work of Ellis and colleagues [3], who introduced both the concept of protein chaperoning and the term molecular chaperone.

Borrelia Genomics as a Tool for Studying Pathogenesis and Vaccine Development

The classical approach to vaccine development requires cultivation of the pathogenic microorganism and concomitant biochemical, serological, and microbiological methods to identify the components important for immunity. This scheme has been successful in many cases, although it is both time-consuming and time-intensive in terms of labor. Whole-genome sequencing has revolutionized the search for vaccine candidates, as it will be possible to predict all of the antigens, independent of their abundance and immunogenicity. This strategy will reduce the need for growth of the pathogen in vitro and for time-consuming biochemical, serological, and microbiological work. The resulting increase in our knowledge of the pathogenicity and virulence of pathogenic microorganisms will facilitate the ease and probability of success in vaccine development. Since this process of vaccine discovery uses sequence information rather than the biological characteristics of the pathogen, it has been named reverse vaccinology (1–3). This approach to vaccine development could also be a tool to develop new vaccine candidates for infections caused by relapsing fever (RF) Borrelia spirochetes and for the development of second-generation vaccine candidates of Lyme disease (LD) Borrelia. This chapter examines how the genome sequence of B. burgdorferi has increased our understanding of the biology of Borrelia spirochetes, and how this knowledge can be used in vaccine development.