Antioxidants May Protect Against Tick-borne Illness

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Antioxidants May Protect Against Tick-borne Illness

http://www.sciencedaily.com/releases/2006/08/060809232944.htm

For hikers, campers and others who enjoy the outdoors, summer can bring concerns

about tick bites and related illnesses such as Rocky Mountain spotted fever.

Researchers are investigating the role that antioxidants -- alpha-lipoic acid

and potentially others like green tea and vitamins C and E, for example -- might

play in preventing or treating the deadly rickettsia bacteria.

The National Institute of Allergy and Infectious Disease, part of the National

Institutes of Health, awarded the University of Rochester Medical Center $2

million for a five-year study of the antioxidant theory. The grant caps more

than a decade of rickettsia research led by Sanjeev Sahni, Ph.D.

Rocky Mountain spotted fever is the most frequently reported illness in the

United States caused by the rickettsia bacteria, which is transmitted by tick

parasites. It usually afflicts otherwise healthy adults and children who are

bitten by wood ticks or dog ticks. The illness can become life threatening if

left untreated, and spotted fever can be difficult for physicians to diagnose

because the earliest signs mimic less-serious viral illnesses. Limiting exposure

to ticks is the best way to prevent the disease. If it does develop, in most

cases doctors can treat it with antibiotics. Typhus is another rickettsial

disease spread by lice or fleas. Although less common, typhus remains a threat

in crowded jails and in other poor hygienic environments.

" Our studies have the potential to identify novel therapeutic targets for a host

of rickettsial diseases, " said Sahni, an assistant professor in

Hematology/Oncology at the University of Rochester.

Dr. Ricketts, who eventually died of typhus, identified rickettsia

in the late 1800s. Sahni's research group first began investigating the

rickettsia bacteria as a model to study the biological changes that occur in the

lining of the blood vessels (endothelium) as the bacteria travels through the

blood stream. Initially they were looking at what types of cellular changes

occur in response to the infection. They discovered that cells undergo oxidative

stress and produce harmful free radicals, causing inflammation and other

complications.

Researchers hypothesized that antioxidants might serve as useful therapies after

examining the damage to infected cells, as seen by electron microscopy, and

through biochemical evidence proving oxidative stress (OS), a term used to

describe a level of damage in cells, tissue and organs. Antioxidants can

generally neutralize free radicals and reduce oxidative damage. Earlier

experiments in which scientists infected cells with rickettsia bacteria and then

treated the cells with alpha-lipoic acid, a powerful antioxidant, showed that

the infected cells did, indeed, marshal a defense against the bacteria.

Sahni is also investigating what enzymes might boost antioxidants to work more

efficiently. His group is studying the process that occurs when infected cells

express cyclooxygenase (-2) and prostaglandins, which results in

inflammation. This biological process is what causes the severe swelling in the

limb that was bitten by a tick harboring the rickettsia bacteria. Sahni

theorizes that regulating the -2 response with -2 inhibitors such as

ibuprofen could also help control the disease.

The University of Rochester team is collaborating with J. Silverman,

Ph.D., of the University of land.