Asthma is a complex syndrome involving potentially permanent airway obstruction, airway hyperresponsiveness, and multicellular inflammation. It is estimated that approximately 300 million people have suffered from asthma worldwide and the burden of this disease in countries as well as families is increasing . Although inhaled steroids can significantly improve the symptoms, curative therapies are not yet available . Moreover, there are also significant concerns regarding the potential side effects from the long term use of conventional drugs, such as corticosteroids. Thus, an effective, low-risk, and non-drug strategy would provide a valuable and adjunctive treatment in asthma management . Complementary and alternative medicine (CAM), such as traditional Chinese herbal remedies, homeopathy as well as acupuncture, is widely applied in the asthma management. It is reported that CAM has been used among 59% of patients with asthma or rhinosinusitis in the United Kingdom, 41% in the United States, 26.5% in Germany, and 27.2% in Singapore .
Acupuncture literally means to puncture with a needle, which is an important therapy in traditional Chinese medicine (TCM) for at least 2,500 years . The theory of acupuncture holds that there are different types of energy flow (qi) in the human body, and the disruptions of qi are believed to be responsible for diseases. Acupuncture practitioners may use thin, solid, metallic needles to correct the imbalances of the flow via the stimulation of special points in the body, which are manipulated manually or by electrical stimulation. The therapy is developed as a relatively global system of medicine and is utilized to treat many diseases. The World Health Organization listed asthma and other 42 indications for acupuncture in 1979  and classified the diseases treated by acupuncture into four categories, 107 illnesses in 2002 . The National Institutes of Health (NIH) has accepted the validity of acupuncture treatment  and recommended it as an adjunctive treatment in comprehensive management programs of addiction, stroke rehabilitation, and asthma, etc [5, 9]. Acupuncture has traditionally been used to treat asthma in China and has been shown to be beneficial in acute asthma in short term [10, 11]. However, well-designed scientific researches in this field are needed and encouraged, which are not only important for elucidating the mechanism, but also useful for exploring new pathways in a systematic manner.
Acupuncture is a complex intervention on diseases and many studies have demonstrated that acupuncture can cause multiple biological responses and regulate many cellular and physiological processes, which could lead to changes of gene expression . These processes could occur at either the proximal or distal ends of acupuncture application, which may be mediated mainly by neural and humoral mechanisms [5, 12]. High-throughput technologies, such as microarray and serial analysis of gene expression (SAGE), may help to reveal and clarify the possible mechanism of acupuncture. In the nerve system, acupuncture was reported to regulate brain aging related genes , suppress several genes in the nociceptive pathways , and up-regulate genes in the spinal cord injury  by using microarray. In the immune and endocrine system, results of microarray have revealed that acupuncture could regulate genes to increase activities of natural killer cell  and superoxide dismutase , to keep the cytokines balance between Th1 and Th2 , and to induce hypocholesterolemic effects . However, these researches focused mainly on the nerve and immune systems, and the analyses of the generated data were limited. SAGE, as a powerful expression profiling method and much more accessible for dissecting the complex system, was applied to qualitatively and quantitatively evaluate the transcription of the genes via particular length without the prerequisite of a hybridization probe for each transcript . However, there has been no SAGE report concerning the mechanism of acupuncture in treating asthma so far.
In this study, four SAGE tag libraries were established respectively from lung tissues of control rats, asthmatic rats, asthmatic rats treated by acupuncture, and control rats treated by acupuncture. The study aimed to systematically analyze and compare the gene expression profiles in the lung of the four different groups, and attempted to examine the molecular mechanism of early airway response (EAR) phase of asthma treated by acupuncture.