Cholesterol pogarsza przebieg anaplasmy

[artur737]

W badaniach na myszach wyszlo, ze wysoki poziom cholesterolu znacznie pogarsza
przebieg infekcji odkleszczowej anaplasma.

J Infect Dis. 2007 May 15;195(10):1497-503. Epub 2007 Apr 3.Click here to read
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High-cholesterol diet facilitates Anaplasma phagocytophilum infection and
up-regulates macrophage inflammatory protein-2 and CXCR2 expression in
apolipoprotein E-deficient mice.
Xiong Q, Wang X, Rikihisa Y.

Department of Veterinary Biosciences, College of Veterinary Medicine, Ohio
State University, Columbus, OH 43210, USA.

BACKGROUND: Anaplasma phagocytophilum is an obligatory intracellular
bacterium that infects granulocytes and causes human granulocytic anaplasmosis
(HGA). This bacterium requires cholesterol for host cell infection in vitro
and incorporates exogenous cholesterol into its membrane. METHODS: To
understand the role of host cholesterol in A. phagocytophilum infection in
vivo, we analyzed the effects of a high-cholesterol diet and reduced
apolipoprotein E (apoE) activity on A. phagocytophilum infection in mice.
RESULTS: A high-cholesterol diet significantly facilitated A. phagocytophilum
infection in the spleen, liver, and blood of apoE-deficient (apoE(-/-)) mice,
compared with the level of infection in apoE(-/-) mice fed a
normal-cholesterol diet or wild-type (WT) mice fed a high- or
normal-cholesterol diet. A. phagocytophilum infection induced a significant
elevation in the mRNA expression of macrophage inflammatory protein (MIP)-2
and an MIP-2 receptor, CXCR2, in the spleen in apoE(-/-) mice fed a
high-cholesterol diet, compared with the other 3 groups. CONCLUSION: Our
results suggest that high blood cholesterol levels resulting from an
interaction between dietary and genetic factors facilitate A. phagocytophilum
infection and up-regulate a proinflammatory chemokine and its receptor, which
may contribute to HGA pathogenesis.

[wroteknowynick]

www.newswise.com/articles/view/531267/
Tick-Related Disease Thrives on Cholesterol

Medical News
Ohio State University
Tue 03-Jul-2007, 00:00 ET

Description
People with high cholesterol levels may be more susceptible to human
granulocytic anaplasmosis (HGA), a disease transmitted by a tick bite.
Results of a new study in mice showed that HGA pathogen levels were 10
times greater in mice that were genetically predisposed to high
cholesterol levels.

*****
Newswise — People who have high cholesterol levels may be much more
susceptible to a particular disease transmitted by the bites of ticks,
a new study in mice suggests.

Scientists infected mice with Anaplasma phagocytophilum, the bacterium
that causes human granulocytic anaplasmosis (HGA), a disease with
flu-like symptoms. Bacteria levels were 10 times greater in mice that
were genetically predisposed to high cholesterol levels and that were
also fed a high-cholesterol diet.

The results confirmed what the researchers had suspected – that A.
phagocytophilum depends on its host's cholesterol stores for its survival.

The implication is that the higher a person's cholesterol levels, the
more susceptible that person may be to developing a severe case of
HGA, said Yasuko Rikihisa, the study's lead author and a professor of
veterinary biosciences at Ohio State University.

Yet HGA is difficult to accurately diagnose, as symptoms are similar
to those of the flu and include high fever, muscle aches, chills and
headaches. But in some cases misdiagnosis can be devastating.

"Young, healthy people probably don't develop very severe symptoms,"
Rikihisa said. "But left undetected, the infection could kill an older
person or someone with a weakened immune system."

She added that immune function slowly declines and blood cholesterol
levels typically increase as we age.

The researchers report their findings in a recent issue of the Journal
of Infectious Diseases. Rikihisa conducted the study with Qingming
Xiong and Xueqi Wang, both graduate students in Rikihisa's laboratory.

Experts say that HGA is on the rise in the United States, where
anywhere from 400 to more than 1,000 people contract the disease each
year. It is transmitted by the bite of Ixodes scapularis, or deer
tick. Deer ticks also spread Lyme disease, and are found primarily in
the upper Midwest, New England, parts of the mid-Atlantic States and
northern California.

The disease attacks immune cells called granulocytes, which the body
normally uses to destroy infectious pathogens.

In the current study, Rikihisa and her colleagues studied two groups
of mice. Animals in one group lacked a protein important for
maintaining normal blood cholesterol levels, while mice in the other
group had this protein, called apoliprotein E (apoE).

For about a month several mice from each group ate a diet high in
cholesterol, while the rest of the animals ate a diet with normal
cholesterol levels. At the end of the month, some of the mice from
each feeding group were infected with A. phagocytophilum.

Ten days after infecting the mice, the researchers collected blood
samples from each mouse and also harvested each animal's spleen and
liver. They determined the extent of the infection based on the amount
of bacteria found in each tissue. Since the spleen and liver both
filter blood, and the liver makes and stores cholesterol, the
researchers thought that they may find higher concentrations of
bacteria in these organs.

A. phagocytophilum levels were 10 times higher in mice predisposed to
high blood cholesterol levels and that ate the high-cholesterol diet
than in any other group of mice, including the animals that were
predisposed and ate a normal-cholesterol diet.

Bacterium levels were highest in the blood and the spleen, and were
quite low in the liver of any of the mice.

Cholesterol levels increased four times in the mice that ate the
high-cholesterol diet and that were predisposed to high cholesterol.
Yet cholesterol levels remained normal in the mice which had the
cholesterol predisposition but consumed the normal-cholesterol diet.

Some people have mutations in the apoE gene, which controls apoE
production. As a result, they cannot adequately maintain blood
cholesterol. In humans, this mutation can cause blood cholesterol
levels to significantly increase when they eat a diet high in
cholesterol, Rikihisa said.

"A high-cholesterol diet really boosted infection levels in the mice
without apoE," Rikihisa said. "The findings suggest that humans may be
more susceptible to HGA if they eat a high-cholesterol diet and if
they are otherwise prone to high blood cholesterol levels."

Studies by other researchers have found a link between older age and
the level of A. phagocytophilum infection. In one study, infected
patients averaged 51 years old, while 39 was the average age for a
person infected with Lyme disease.

"Our blood cholesterol levels generally rise as we age," Rikihisa
said. "Someone who suspects he was bitten by a tick needs to seek
prompt antibiotic therapy. Additionally, lowering cholesterol levels
through diet or with medication may help decrease the chance of
developing HGA, or at least reduce the severity of its symptoms."

A grant from the National Institutes of Health supported this work.

[wroteknowynick]

Jest to niezmiernie ciekawe ponieważ cholesterol służy do produkcji witaminy d i
sam jest steroidem.