Tag Archives: Phagocyte

Artery hardening bacteria identified

Scientists have identified specific bacteria that may have a key role in vascular pathogenesis, specifically atherosclerosis, or what is commonly referred to as ‘hardening of the arteries’.

Using tissue specimens from the Department of Surgery and the Herbert Irving Comprehensive Cancer Center at Columbia University College of Dental Medicine, Dr. Emil Kozarov and his team isolated plaques from a 78-year-old man who had previously suffered a heart attack.

In the study, researchers describe processing the tissue using cell cultures and genomic analysis to look for the presence of culturable bacteria. In addition, they looked at five pairs of diseased and healthy arterial tissue.

The use of cell cultures aided in the isolation of the bacillus Enterobacter hormaechei from the patient”s tissue. Implicated in bloodstream infections and other life-threatening conditions, the isolated bacteria were resistant to multiple antibiotics.

Hardening of the arteries

Hardening of the arteries

Surprisingly, using quantitative methods, this microbe was further identified in very high numbers in the patient but not in healthy arterial tissues.

One specific avenue of infection the researchers studied involved bacteria getting access to the circulatory system via internalization in white blood cells (phagocytes) designed to ingest harmful foreign particles.


The model that Kozarov”s team was able to demonstrate showed an intermediate step where Enterobacter hormaechei is internalized by the phagocytic cells, but a step wherein bacteria are able to avoid immediate death in phagocytes.

Once in circulation, Kozarov said, bacteria using this ‘Trojan horse’ approach can persist in the organism for extended periods of time while traveling to and colonizing distant sites.

This can lead to multitude of problems for the patients and for the clinicians: failure of antibiotic treatment, vascular tissue colonization and initiation of an inflammatory process, or atherosclerosis, which ultimately can lead to heart attack or stroke.

“Our findings warrant further studies of bacterial infections as a contributing factor to cardiovascular disease, and of the concept that ‘bacterial persistence’ in phagocytic cells likely contributes to systemic dissemination,” said Kozarov.

The findings are published in the latest Journal of Atherosclerosis and Thrombosis.

Statins may ward off infections

Cholesterol-lowering drugs have a useful side effect – killing bacteria, scientists have discovered.

The statin drugs taken by millions of people around the world to cut their risk of heart disease may protect against serious infections such as pneumonia, researchers believe.

A US study found that the medications activate the bacteria-killing properties of white blood cells.

Simvastatin

Simvastatin

In laboratory experiments, phagocyte blood cells that kill and ingest foreign invaders became more effective after being exposed to statins.

The phagocytes were prompted to release “extracellular traps” – net-like webs of DNA-based filaments embedded with anti-microbial molecules. The traps ensnare and kill bacteria before they have a chance to spread in the body.

Professor Victor Nizet, from the University of California at San Diego, who led the research, said: “We found these drugs fundamentally alter how white blood cells behave upon encountering bacteria.”


The study was reported today in the journal Cell Host & Microbe.

Cathy Ross, from the British Heart Foundation, said: “The results are scientifically interesting and support the fact that we know statins have extra health benefits, in addition to lowering cholesterol.

“However, this is not a reason to prescribe them to the general population. For those already taking statins for heart disease, these added benefits may offer a small level of protection against bacterial infections.”