Groene
thee tegen Rheumatische Artritis, botontkalking en voor goede gewrichten.*
Uit
twee nieuwe studies blijkt dat groene thee
ook zeer goed kan werken om Reumatische
Artritis (RA) te verzachten, te voorkomen en de bot- en kraakbeenafbraak in
gewrichten kan voorkomen. De belangrijkste bioactieve stoffen die daarvoor
verantwoordelijk zijn en in de laboratoriumstudies ook gebruikt werden zijn de
catechinen EGCG. EGCG blijkt in staat om ontstekingsenzymen die zorgen voor de
degeneratie van de gewrichten duidelijk af te remmen.
-- Green tea, already
touted for its cardiovascular and anticancer benefits, may also help ease the
inflammation and pain of rheumatoid arthritis, a new study suggests.
The study was conducted
in the laboratory, and its findings are preliminary, stressed lead researcher
Salah-uddin Ahmed, an investigator at the University of Michigan Health System,
in Ann Arbor.
"It's too early"
to fully recommend green tea to ease rheumatoid arthritis, he said, but the
study "is a starting point."
Ahmed was scheduled to
present the research Sunday at the Experimental Biology meeting, in Washington,
D.C.
For the study, Ahmed
isolated cells called synovial fibroblasts from the joints of patients with
rheumatoid arthritis. These cells form a lining of tissue surrounding the
capsule of the joints.
In patients with
rheumatoid arthritis, this lining is inflamed, leading to long-term joint damage
and chronic pain. About 2.1 million Americans have rheumatoid arthritis,
according to the Arthritis Foundation.
Ahmed's team next
cultured these cells and exposed them to the active ingredient in green tea, a
compound named epigallocatechin-3-gallate (EGCG). Next, the cells were
stimulated with a protein of the immune system known to play a role in causing
joint degradation in rheumatoid arthritis. The protein is called cytokine
interleukin-1 beta or IL-1B.
"IL-1B is a major
player in mediating cartilage degradation," Ahmed explained.
In an earlier study,
Ahmed's team found that fibroblasts pretreated with EGCG and then stimulated
with cytokine IL-1B were better able to block IL-1B's ability to produce
damaging proteins and enzymes. Those proteins and enzymes can infiltrate the
joints and cause the cartilage breakdown seen in people with rheumatoid
arthritis.
In the more recent study,
the researchers focused on whether EGCG had the ability to block the activity of
two potent molecules, IL-6 and cyclooxygenase-2 (Cox-2), which also play a role
in breaking down bone in an RA joint.
The two molecules were
suppressed by the EGCG, Ahmed's team found. While he said it is difficult to
quantify exactly the effect of the suppression, the EGCG "blocked them
significantly," he said.
EGCG also blocked the
production of prostaglandin E2, another compound that can cause joint
inflammation.
One expert said the new
green tea study was intriguing. "This study is very specific," said
Stephen Hsu, an associate professor of dentistry, molecular medicine and
genetics at the medical College of Georgia in Augusta.
In his own research, Hsu
has found that green tea may help protect against certain autoimmune diseases,
in which the body triggers an immune response, basically attacking its own cells.
Hsu studied EGCG's effect in helping to inhibit an autoimmune disorder known as
Sjogren's syndrome, in which the salivary glands are affected, and in lupus, in
which the skin is affected.
The new research by Ahmed
is one of the first to focus on rheumatoid arthritis and green tea, Hsu said. If
it bears out, it could be good news for rheumatoid arthritis patients, perhaps
offering them a non-drug option to keep pain under control, he said.
Ahmed cautioned that it's
too soon to advise rheumatoid arthritis patients to drink green tea. On the
other hand, drinking green tea certainly wouldn't hurt, he said, since it is
known to have many health benefits and no known side effects.
He said people might want
to try drinking three or four 8-ounce cups of green tea per day. "Try
different brands," he suggested. The flavors may taste slightly different.
"Drink it continuously throughout the day," he said, to keep blood
levels more constant.
And you might want to
consider popping some tart cherries along with that tea, according to another
study presented at the same meeting.
In the study, conducted
by another team of University of Michigan researchers, powdered tart cherries
appeared to lower total cholesterol and blood sugar and help the body handle fat
and sugar -- at least in animals.
Factors
Causing Cartilage, Bone Destruction In Arthritis Suppressed By Green Tea
Compound
In
rheumatoid arthritis, a person's own immune system attacks the joints by
activating the synovial tissue that lines the body's movable joints, causing
inflammation, swelling, pain and eventually erosion of the bone and cartilage
and deformation of the joint. It is among the most debilitating forms of
arthritis, often making difficult even the simplest of daily activities.
In a study presented at Experimental Biology 2007, University of Michigan
Medical School scientist Dr. Salah-uddin Ahmed reported that a compound derived
from green tea was able to inhibit production of several immune system molecules
involved in inflammation and joint damage. The compound, named epigallocatechin-3-gallate
(EGCG), an active principal of green tea extract, is a potent anti-inflammatory
molecule, and also was able to inhibit production of interleukin-6 (IL-6) and
prostaglandin E2, the inflammatory products found in the connective tissue of
people with rheumatoid arthritis.
Dr. Ahmed's Experimental Biology presentation was part of the scientific program
of the American Society for Nutrition.
Synovial fibroblasts (cells that form a lining of synovial tissue surrounding
the capsule of the joints) were isolated from the joints of the patients
suffering from rheumatoid arthritis, cultured in growth medium, and incubated
with EGCG. Synovial fibroblasts were then stimulated with pro-inflammatory
cytokine IL-1ß, a protein of the immune system known to play an important
role in causing joint destruction in rheumatoid arthritis.
In an earlier study published by Dr. Ahmed's research group last fall, the
researchers showed some interesting and novel findings when EGCG pretreated
synovial fibroblasts were stimulated with the cytokine IL-1ß to study the
protective effect of this green tea compound. Compared to untreated synovial
fibroblasts, the cells treated with EGCG markedly blocked IL-1ß's ability to
produce the proteins and enzymes that infiltrate the joints of persons with
rheumatoid arthritis causing cartilage degradation.
The scientists decided to extend their study to see if the green tea compound
also has the capability to block the activity of two other potent molecules, IL-6
and cyclooxygenase-2 (COX-2), actively involved in causing bone erosion in the
RA joint. In the new study presented at Experimental Biology, the scientists
once again isolated synovial fibroblasts taken from the joints of patients
suffering from rheumatoid arthritis and incubated these cells with the green tea
compound. When untreated cells were stimulated with IL-1ß, a sequence of
molecular events occurred that resulted in production of the bone-destructive
molecules. But the scientists found that pre-incubation with EGCG was capable of
blocking the production of these molecules in a dose-dependent manner.
Furthermore, EGCG also inhibited the production of prostaglandin E2, which
causes inflammation in the joints.
The cell signaling pathways that regulate levels of these immune system
molecules under both normal and rheumatoid arthritis situations is well
established, and the researchers were able to trace the effects of the green tea
compound infusion to see that it worked by inhibiting these pathways.
Dr. Ahmed says that these studies suggest that EGCG or molecules that could be
derived synthetically from the EGCG found in green tea may be of therapeutic
value in inhibiting the joint destruction in this challenging disease. The
laboratory now is focused on the inhibitory role of EGCG in gene expression. The
scientists plan to give EGCG orally to mice genetically bred to be animal models
of rheumatoid arthritis to see if it provides similar therapeutic or preventive
effects. Dr. Ahmed believes these studies will form a strong foundation for
future testing of green tea compounds in humans with rheumatoid arthritis.
###
Co-authors of the study are Dr. Angela Pakozdi and Dr. Alisa Koch of the
University of Michigan and the Veterans Affairs Medical Center in Ann Arbor.
This research was supported by NIH grants and Veteran Administration Medical
Research Service funds to Dr. Alisa Koch.
(Mei 2007)