News Feature
Nature 448, 126-128 (12 July 2007) | doi:10.1038/448126a; Published
online 11 July 2007
Traditional medicine: A culture in the balance
Jane Qiu1
1. Jane Qiu writes for Nature from Beijing.
Traditional Chinese medicine and Western science face almost
irreconcilable differences. Can systems biology bring them together?
Jane Qiu reports.
Liu Wen-long's modest Beijing practice looks no different from most
clinics. But he is no ordinary doctor. Liu never orders lab tests, nor
does he prescribe high-tech imaging diagnostics. He relies on simple
observations, checking a patient's pulse, complexion and odour, and
asking about habits and medical history. At 69 years old, he has been
practising traditional Chinese medicine for 43 years and he is
resolute about its benefits. "People keep coming back because it cures
them and improves their well-being," he says.
Indeed, patients trickle in to see Liu all morning for conditions
ranging from allergies to lung cancer. Some are nervous first-timers,
others are regulars, confident in what traditional Chinese medicine
has to offer. Ms Huang, an accountant from the outskirts of Beijing,
is delighted that her migraines, which haunted her for years,
disappeared after three herbal regimens. "I used to live on
painkillers and felt tired all the time," she says. "I am now a
totally different person."
In a country that is fiercely embracing modernity, clinics such as
Liu's, which have been operating the same way for thousands of years,
seem vulnerable and out of place. Indeed, attitudes on traditional
Chinese medicine have divided the country. Last year, Zhang Gong-yao,
from the Central South University in Changsha, Hunan, published an
article in a Chinese journal calling traditional Chinese medicine a
pseudoscience that should be banished from public healthcare and
research1. The article caused uproar in the country, and earlier this
year the government announced an ambitious plan to modernize the
millennia-old practice2.
But should such a formidable gap be bridged? Modern Western medicine
generally prescribes treatments for specific diseases, often on the
basis of their physiological cause. Traditional Chinese medicine,
however, focuses on symptoms, and uses plant and animal products,
minerals, acupuncture and moxibustion — the burning of the mugwort
herb (Artemisia vulgaris) on or near the skin. But whether these
methods are effective and, if they are, how they work remain a source
of some derision. The greatest divide is in the testing. In the West,
researchers test a drug's safety and efficacy in randomized,
controlled trials. Traditional Chinese treatments are mixtures of
ingredients, concocted on the spot on the basis of a patient's
symptoms and characteristics and using theories passed down through
generations.
The mainstream medical community, in China and abroad, has been highly
critical of the underlying theories. Traditional Chinese medicine is
based on ideas such as qi (meridian), in which illness is caused by
blocked energy channels; yin and yang, which emphasizes the balance of
energy; and wuxing (five elements), in which people's organs and
health status are categorized according to their 'elemental
characteristics': fire, wood, water, earth and metal.
Pharmaceutical companies have become more interested in traditional
Chinese medicines over the past decade. But their approach has been
characteristically Western: isolate the active ingredients and test
them one at a time. This reductionist approach has led to the approval
of drugs such as artemisinin for malaria, which is used to treat fever
in traditional Chinese medicine, and arsenic trioxide, which has been
carried over from Chinese medicine for treatment of acute
promyelocytic leukaemia.
But identifying the active ingredients isn't easy. Most remedies in
traditional Chinese medicine, as it turns out, are compound formulae
— or fufang — that contain as many as 50 species of herbs, and
thousands of chemicals therein (see 'Knowledge mining'). To tap into
the deeper well of traditional Chinese treatments, researchers think
they may need to look at how the mixtures of ingredients act in concert.
Relaxed regulation
The criteria for approval of herbal mixtures as medicines are now
starting to relax, at least in the United States. In June 2004, the US
Food and Drug Administration (FDA) issued new guidelines that permit
the approval of herbal mixtures if they can be shown to be safe and
effective, even if the active constituents are not known. Last October,
the FDA approved the first such botanical drug under the new rules, a
proprietary mixture of green-tea extracts called Veregen developed by
the German company MediGene for treating genital warts.
These new regulations have helped to renew industry's interest in the
complex formulae. And a buzzing new Western field could be poised to
capitalize on the deeper secrets of traditional Chinese medicine.
Systems biology attempts to understand the function and behaviour of
an organism by studying the interactions between its components. It
has been called a more holistic approach to biology and is seen by
some as a perfect match for traditional Chinese medicine.
By measuring many genes, proteins and metabolites at the same time,
systems biology may provide a measure of the entire body's response to
a complex mixture of herbs. "If there is any technology that could
lead to a breakthrough in traditional Chinese medicine, it will be
systems biology," says Robert Verpoorte, head of the pharmacognosy
department at the University of Leiden in the Netherlands. But not
everyone agrees that the new technology is equipped to test old ideas.
Jia Wei, a pharmacologist at the Shanghai Centre for Systems
Biomedicine at Jiao Tong University, and Tang Hui-ru at the Wuhan
Institute of Physics and Mathematics, part of the Chinese Academy of
Sciences, want to understand more fully how herbal extracts affect the
whole body. They are collaborating with Jeremy Nicholson, head of the
department of biomolecular medicine at Imperial College London, and
using technologies such as nuclear magnetic resonance spectroscopy and
mass spectrometry to profile the metabolites in a person's urine or
blood — a discipline they call metabonomics.
Jia and his colleagues found that rats given the compound
1,2-dimethylhydrazine to induce tumours in their colons had different
metabolic profiles in their urine from those in the control group. And
by feeding the rats a combination of two herbal extracts — Coptidis
rhizoma and Evodia rutaecarpa, which are widely used in traditional
Chinese medicine to treat gastric conditions — the researchers were
able to reverse these changes in metabolism. Their results have not
yet been published, but the researchers say that by looking at the
changes in metabolites in detail, they have pinpointed the metabolic
pathways that the herbs affect.
Culture shift
Jan van der Greef from SU Biomedicine in Zeist, the Netherlands, and
his colleague Wang Mei are using a similar approach. In a mouse model
of metabolic syndrome — a cluster of conditions such as insulin
resistance and high blood pressure that often occur together — they
and their team looked at the effect of an undisclosed formula used in
traditional Chinese medicine on lipid profiles. When these mice are
fed a high-fat diet, they become more resistant to insulin. The lipid
profiles of these mice were clearly distinguishable from those of mice
fed a normal diet, and they shifted towards the healthy state when the
mice were given traditional Chinese medicine3.
The researchers noticed that the profile shift resembled that caused
by the Western obesity drug Rimonabant, which acts on proteins called
CB-1 endocannabinoid receptors. And their unpublished work with cell
culture suggests that herbal extracts can affect lipid metabolism
through the same receptor, says van der Greef. The team is now testing
the formula in clinical trials.
Although one active ingredient may act as the Western drug, the
uncertain role of additional ingredients and the variability of active
ingredients confounds Western sensibilities. "Variations worry
people," Nicholson says. The same plant species grown in different
regions and harvested in different seasons could have distinct
chemical compositions. This has always been a vexing issue for
herbal-medicine researchers.
While at Nicholson's lab, Tang and his colleagues analysed the
molecular components in chamomile plants from Egypt, Slovakia, and
Hungary, and could classify them easily4. Using similar approaches,
the team from the Wuhan Institute of Physics and Mathematics found
significant variations in the same herbal medicines produced by
different companies and even between different batches produced by the
same company. "This is an issue China must tackle for its herbal
medicines to raise their game in the world market," says Tang.
To many self-purported systems biologists, several approaches are
needed to build a complete picture of a living organism and to
understand the effect of traditional Chinese medicine. Nevertheless,
systems biology has been a conspicuously hard field to define. Many
have used the term loosely, and pioneers in the field contend that the
technologies haven't been honed to the point that they could be used
for these approaches.
"It's conceivable that systems biology could find applications in
trying to sort out components in Chinese herbal medicine, but it's
very early days," says Leroy Hood, president of the Institute for
Systems Biology in Seattle, Washington, and regarded as the field's
founding father. "It would be an enormous challenge at this point and
time."
Systems biology has been successful in model organisms, according to
Hood, but is much less so in human studies. Many hurdles need to be
overcome before researchers could even begin to contemplate how to
deal with subjects as complex as traditional Chinese medicine. For
example, better detection systems are needed to measure metabolites,
especially proteins, accurately in the blood, and more powerful
computational and statistical tools are crucial for dealing with large
and complex data sets. "Those technologies are at early stages of
maturation," Hood says.
There are also broader concerns about the modernization of traditional
Chinese medicine, from both advocates and sceptics of the practice.
Some are uncomfortable with separating the study and development of
Chinese herbal medicines from the theories that underlie its normal
practice. "Traditional Chinese medicine is not just a medical system,
but a branch of philosophy and healing art that is an important part
of Chinese culture," says Fu Jing-hua, a retired researcher at the
Chinese Academy of Chinese Medicine Sciences in Beijing and president
of the Chinese Ancient Books Publishing House in Beijing. "Devoid of
that cultural context, it would become a tree without roots."
Lofty ideals
But Zhang and Fang Shi-min, a US-trained biochemist who now runs a
society called New Threads that is known for fighting pseudoscience
and research misconduct in China say that it is exactly those
traditional Chinese medicine theories that should be abolished.
Conceits such as yin and yang, wuxing and qi "are inaccurate
descriptions of the human body that verge on imagination", he says.
Inevitably, cultural factors may be the biggest obstacle in bridging
the East–West gap. "The field of traditional Chinese medicine is
notorious for being averse to criticism," says Yuan Zhong, a
philosopher of medicine at the Chinese Academy of Medical Sciences.
"If people are not allowed to disagree or voice their opinions, there
would be no hope of progress for any discipline."
But although heated exchanges are boiling over in debates on the
future of traditional Chinese medicine, it's business as usual in
Liu's practice. He is sanguine about the convergence between
traditional Chinese medicine and Western medicine, but has a pragmatic
attitude towards it. "Whether from the East or the West, we share the
same goal of improving human health. As long as it works, anything
goes," he remarks. But Liu says that he is yet to see any real
progress in the merging of the two philosophies and, until then, his
intuition and experience — as well as traditional Chinese medicine's
seemingly arcane theory and practice — will serve him and his
patients just fine.
See Editorial, page 106.
References
1. Zhang, G.-Y. Med. Phil. 27, 14–17 (2006).
2. Qiu, J. Nature 446, 590–591 (2007). | Article |
3. Wang, M. et al. Phytother. Res. 19, 173–182 (2005). | Article |
PubMed | ChemPort |
4. Wang, Y. et al. Planta Med. 70, 250–255 (2004).
Editorial
Nature 448, 105-106 (12 July 2007) | doi:10.1038/448106a; Published
online 11 July 2007
Hard to swallow
Is it possible to gauge the true potential of traditional Chinese
medicine?
Researchers, practitioners and drug companies around the world are
engaged in a complex, tentative dance over the best way to tap into
the unknown potential of traditional Chinese medicine. The scientific
community and the drug industry both tend to be sniffy about
'traditional' cures; yet there is a strong sense that millennia of
practice in China — much of it barely documented — is likely to have
yielded at least some treatments that work.
Pharmaceutical companies are understandably eager to enter a Chinese
domestic market that was estimated by the Boston Consulting Group to
be worth US$13 billion last year, and growing fast. But they are
tantalized by one opportunity above all: the prospect that the
nation's traditional medicine might contain a number of potentially
profitable compounds hidden somewhere in its arcane array of potions
and herbal mixtures.
The task of finding these elusive gems has been approached in a
typically reductionist manner, with researchers seeking single
compounds that might have a role in treating specific diseases.
Sometimes this has been successful: artemisinin, for example, which is
currently the most effective treatment for malaria, was fished out of
a herbal treatment for fevers. But such success stories have been few
and far between.
So if traditional Chinese medicine is so great, why hasn't the
qualitative study of its outcomes opened the door to a flood of cures?
The most obvious answer is that it actually has little to offer: it is
largely just pseudoscience, with no rational mechanism of action for
most of its therapies. Advocates respond by claiming that researchers
are missing aspects of the art, notably the interactions between
different ingredients in traditional therapies.
Nevertheless, the drug industry is not exactly awash with promising
new medicines at the moment. Perhaps as a result, the global
regulatory process has become increasingly receptive to traditional
approaches. In 2004, for example, the US Food and Drug Administration
issued new guidelines on botanical drugs that made it much easier to
get extracts into clinical trials if there was some history of prior
use, and that obviated the need to characterize all compounds in an
extract.
Some researchers in China and elsewhere, meanwhile, are advocating
systems biology — the study of the interactions between proteins,
genes, metabolites and components of cells or organisms — as a way to
assess the usefulness of traditional medicines (see page 126).
Constructive approaches to divining the potential usefulness of
traditional therapies are to be welcomed. But it seems problematic to
apply a brand new technique, largely untested in the clinic, to test
the veracity of traditional Chinese medicine, when the field is so
fraught with pseudoscience. In the meantime, claims made on behalf of
an uncharted body of knowledge should be treated with the customary
scepticism that is the bedrock of both science and medicine. |
发表于 2007-7-23 22:18
