Cholesterol’s link to heart disease gets clearer - and more complicated
By considering molecular level events on a broader scale, researchers now have a clearer, if more complicated, picture of how one class of immune cells goes wrong when loaded with cholesterol. The findings reported in the February 3rd issue of Cell Metabolism, a Cell Press publication, show that, when it comes to the development of atherosclerosis and heart disease, it’s not about any one bad actor - it’s about a network gone awry.

The new findings also highlight a pretty remarkable thing, Heinecke says: “Despite 30 years of study, we still don’t know how cholesterol causes heart disease.” But, with the new findings, scientists are getting closer.

Earlier studies had shown that heart disease is about more than just high LDL (”bad”) cholesterol. Cells known as macrophages also play a critical role. Macrophages are part of the innate immune system that typically gobble up pathogens and clear away dead cells. But they also take up and degrade cholesterol derivatives. When they get overloaded with those lipoproteins, they take on a foamy appearance under the microscope to become what scientists aptly refer to as foam cells. Those foam cells are the ones that seem to have critical importance in the development of atherosclerosis.

People had typically thought about this problem in terms of linear pathways, Heinecke explained. In essence, macrophages end up with too much cholesterol going in and not enough coming out. The macrophages get overwhelmed and trapped in the artery wall, and somehow plaques form as a result.

But the new results show that it isn’t really about simple paths in and out; rather, there is an integrated network of macrophage proteins involved. When that network gets disrupted, as it does when too much cholesterol comes in, atherosclerosis forms. “It’s definitely a different way to think about what is going on,” Heinecke says.

Heinecke’s group applied sophisticated technologies and statistical tools to get a global view of what happens to macrophage proteins when they turn into foam cells. Their analysis revealed what they call a macrophage sterol responsive network (MSRN), including proteins already known to work together. Most of them are also found in one place, within microvesicles outside the macrophage cells.

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CORVALLIS, Ore. - A string of recent discoveries about the multiple health benefits of vitamin D has renewed interest in this multi purpose nutrient, increased awareness of the huge numbers of people who are deficient in it, spurred research and even led to an appreciation of it as “nature’s antibiotic.” On issues ranging from the health of your immune system to prevention of heart disease and even vulnerability to influenza, vitamin D is now seen as one of the most critical nutrients for overall health. But it’s also one of those most likely to be deficient - especially during winter when production of the “sunshine vitamin” almost grinds to a halt for millions of people in the United States, Europe and other northern temperate zones.

Analogs of the vitamin are even being considered for use as new therapies against tuberculosis, AIDS, and other concerns. And federal experts are considering an increase in the recommended daily intake of the vitamin as more evidence of its value emerges, especially for the elderly.

“About 70 percent of the population of the United States has insufficient levels of vitamin D,” said Adrian Gombart, a principal investigator with the Linus Pauling Institute at Oregon State University. “This is a critical issue as we learn more about the many roles it may play in fighting infection, balancing your immune response, helping to address autoimmune problems, and even preventing heart disease.”

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Canadians of lower socioeconomic status at greatest risk The prevalence of heart disease and certain key risk factors - hypertension, diabetes, and obesity - are increasing in all age groups and most income groups in Canada found a new study published in CMAJ (Canadian Medical Association Journal) http://www.cmaj.ca/press/cmaj081629.pdf (www.cmaj.ca). This study, which looked at national data from 1994 to 2005, encompassed people aged 12 years and older sampling from Canadians of all socioeconomic and ethnic groups. Risk factors such as hypertension, diabetes, and obesity increased most rapidly among younger people between 12 to 50 years of age.

The study was conducted by researchers from the Institute for Clinical Evaluative Sciences, University Health Network, University of Toronto, Sunnybrook Health Sciences Centre, Toronto; Queen’s University, Kingston, Ontario; University of Alberta, University of Calgary, Alberta; Dalhousie University, Halifax, Nova Scotia; and Statistics Canada. It was funded by the Canadian Institutes of Health Research (CIHR).

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Bacteria that can cause serious heart disease in humans are being spread by rat fleas, sparking concern that the infections could become a bigger problem in humans. Research published in the December issue of the Journal of Medical Microbiology suggests that brown rats, the biggest and most common rats in Europe, may now be carrying the bacteria. Since the early 1990s, more than 20 species of Bartonella bacteria have been discovered. They are considered to be emerging zoonotic pathogens, because they can cause serious illness in humans worldwide from heart disease to infection of the spleen and nervous system.

“A new species called Bartonella rochalimae was recently discovered in a patient with an enlarged spleen who had travelled to South America,” said Professor Chao-Chin Chang from the National Chung Hsing University in Taiwan. “This event raised concern that it could be a newly emerged zoonotic pathogen. Therefore, we decided to investigate further to understand if rodents living close to human environment could carry this bacteria.”

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