The present invention relates to use of polysaccharides obtained from Dendrobium for treating an allergic disease or for reducing airway-remodeling caused by inflammation.

Description of the Invention

TECHNICAL FIELD

This invention relates to treating allergic diseases with polysaccharides isolated from Dendrobium.

BACKGROUND

Dendrobium is a genus of tropical orchids widely distributed in Asia, Europe, and Australia. Some of its species have a long history of use in traditional Chinese medicine for improving skin quality and vision. It has also been reported that Dendrobium exhibits antioxidation, anti-inflammation, and immune-regulation activities. See Satoh et al., Biochem. Pharmacol. 51: 339-343, 1996; Yamaguchi et al., Cordyceps sinensis. Phytoher. Res. 14: 647-649, 2000; Zhao et al., J. Biochem. Molecular Bio. 40(5): 670-677, 2007; and US 20060251739.

SUMMARY OF THE INVENTION

This invention is based on the unexpected discoveries that polysaccharides prepared from Dendrobii Herba (i.e., Dendrobium stem) are effective in treating allergic diseases such as asthma, pollen allergy, and atopic dermatitis.

Accordingly, the present invention provides a method of treating an allergic disease (e.g., asthma, pollen allergy, allergic conjunctivitis, or atopic determitis) by administering (e.g., orally) to a subject an effective amount of polysaccharides prepared from Dendrobii Herba.

The term "treating" as used herein refers to the application or administration of a composition including one or more active agents to a subject, who has an allergic disease, a symptom of the allergic disease, or a predisposition toward the allergic disease, with the purpose to cure, heal, alleviate, relieve, alter, remedy, ameliorate, improve, or affect the disease, the symptoms of the disease, or the predisposition toward the disease. "An effective amount" as used herein refers to the amount of each active agent required to confer therapeutic effect on the subject, either alone or in combination with one or more other active agents. Effective amounts vary, as recognized by those skilled in the art, depending on route of administration, excipient usage, and co-usage with other active agents.

In one example, the polysaccharides used to practice the method of this invention are prepared by a process including at least the following five steps: i. soaking a first Dendrobii Herba preparation in a first alcohol (e.g., methanol, ethanol, or a mixture thereof), ii. removing the first alcohol to produce a second Dendrobii Herba preparation; iii. extracting the second Dendrobii Herba preparation with water (i.e., pure water or a suitable water-containing solvent) to obtain an aqueous solution; (iv) mixing the aqueous solution with a second alcohol (e.g., 50% ethanol by volume) to allow precipitation of polysaccharides, and (v) collecting the precipitated polysaccharides.

The present invention further provides a method of reducing airway-remodeling resulted from inflammation by administrating to a subject in need thereof an effective amount of the polysaccharides described above.

Also within the scope of this invention is use of the polysaccharides described herein for treating an allergic disease or reducing inflammation-induced airway-remodeling, or for the manufacture of a medicament for these treatments.

DETAILED DESCRIPTION OF THE INVENTION

Described herein is use of Dendrobii Herba polysaccharides for treating an allergic disease. "Polysaccharides" are polymers each consisting of a number of monosaccharides joined by glycosidic bonds. A polysaccharide molecule includes more than 10 monosaccharides of any types, e.g., glucose, fructose, galactose, xylose, or ribose. It can have a linear or a branched structure.

The polysaccharides used to practice the method of this invention can be prepared from Dendrobii Herba via any conventional methods. One example follows. Stems of a Dendrobium plant (e.g., Dendrobium loddigesii, Dendrobium fimbriatum var. oculatum, Dendrobium chrysanthum, Dendrobium candidum ex Lindl, or Dendrobium nobil) are collected, dried, and soaked in an alcohol (e.g., methanol, ethanol, or a mixture thereof) for a suitable period of time (e.g., 1-12 hours). After removing the alcohol via, e.g., evaporation, the resultant Dendrobium stems are soaked in pure water or a suitable water-containing solvent for a sufficient period of time (e.g., 12-16 hours). The water-containing solvent can be an aqueous salt (e.g., NaCl or KCl) solution, or a mixture containing >70% (e.g., 80%, 90%, or 95%) by volume water and <30% by volume a water miscible solvent (e.g., methanol or ethanol). Insoluble substances are removed via centrifugation or filtration, resulting in a soluble fraction. This fraction is then mixed with an alcohol (e.g., 30-70% ethanol) to precipitate polysaccharides. Optionally, before being mixed with the alcohol, the water-soluble fraction is diluted in warm water and kept at 50-70.degree. C. for 20-60 minutes. The precipitates are collected by, e.g., centrifugation, and preferably, dried, to obtained the polysaccharides to be used in the method of this invention.

The Dendrobii Herba polysaccharides described above can be mixed with a pharmaceutically acceptable carrier, and optionally with another therapeutically active agent, to form a pharmaceutical composition. The carrier in the pharmaceutical composition must be "acceptable" in the sense that it is compatible with the active ingredient of the composition (and preferably, capable of stabilizing the active ingredient) and not deleterious to the subject to be treated. One or more solubilizing agents can be utilized as pharmaceutical excipients for delivery of the polysaccharide-containing pharmaceutical composition. Examples of other carriers include dextrine, silicon oxide, magnesium stearate, cellulose, sodium lauryl sulfate, D&C Yellow #10, microcrystalline cellulose, mannitol, glucose, defatted milk powder, polyvinylpyrrolidone, and starch, or a combination thereof This pharmaceutical composition can then be presented in a variety of forms, such as tablet, capsule, powder, gel, or liquid.

The pharmaceutical composition is administered to a subject via suitable routes, e.g., oral administration, once or multiple times per day or administered once every several days. A solid formulation for oral administration can contain suitable carriers or excipients, such as corn starch, gelatin, lactose, acacia, sucrose, microcrystalline cellulose, kaolin, mannitol, dicalcium phosphate, calcium carbonate, sodium chloride, or alginic acid. Disintegrators that can be used include, without limitation, microglycolate, and alginic acid. Tablet binders that can be used include acacia, methylcellulose, sodium carboxymethylcellulose, polyvinylpyrrolidone (Povidone3), hydroxypropyl methylcellulose, sucrose, starch, and ethylcellulose. Lubricants that can be used include magnesium stearates, stearic acid, silicone fluid, talc, waxes, oils, and colloidal silica.

This solid formulation can be designed such that the composition is released in the intestine. For example, the composition is confined in a solid sub-unit or a capsule compartment that have respectively a matrix or a wall or a closure comprising an enteric polymer which dissolves or disperses at the pH of the small or large intestine to release the drug substance in the intestine.

In another example, the polysaccharides described above is mixed with one or more edible carriers to form a food product (e.g., yogurt, milk, or soy milk), or a food supplement (e.g., a nutrient supply or an herbal product). Examples of an edible carrier include starch, cyclodextrin, maltodextrin, methylcellulose, carbonmethoxy cellulose, xanthan gum, and aqueous solutions thereof Such food products can be prepared by methods well known in the food industry. As used herein, the term "food" broadly refers to any kinds of liquid and solid/semi-solid materials that are used for nourishing humans and animals, for sustaining normal or accelerated growth, or for maintaining stamina or alertness.

The polysaccharides described herein can be used to treat allergic diseases, e.g., allergic diseases associated with an increased level of eosinophil, IgE, a chemokine, or a Th2 cytokine. It is well known that an allergen triggers a cascade of immune responses, including T cell differentiation to Th2 effector cells; release of Th2 cytokine (e.g., IL-4, IL-5, IL-6, and IL-13), production of IgE; and activation of neutrophils such as eosinophils or mast cells. The immune responses triggered by an allergen result in various allergic diseases, such as asthma, pollen allergy, allergic conjunctivitis, and atopic dermatitis.

Asthma is a chronic illness involving the respiratory system. The cardinal features in humans are airway inflammation, hypersecretion of highly viscous mucus, and bronchoconstriction. This airway narrowing causes symptoms such as wheezing, shortness of breath, chest tightness, and coughing. These features may be triggered by such things as exposure to an environmental stimulant (or allergen), cold air, warm air, moist air, or emotional stress. In addition, allergic sensitization is also defined by production of IgE against environmental antigens, recruitment of lymphocyte and eosinophil into the lungs and in serum, and inducing the production of Th2 cytokines or chemokines. Public attention in the developed world has recently focused on asthma because of its rapidly increasing prevalence, affecting up to one in four urban children. See Craig M. Lilly, Journal of Allergy and Clinical Immunology, Vol. 115, Issue 4, Supplement 1, April 2005, Pages S526-S531.

The same as asthma, allergic conjunctivitis and atopic dermatitis both result from hypersensitive to allergen, such as pollen; however, the inflamed region and symptoms are varied. Similarly, these allergic diseases are also related to excess of Th2 cytokines or chemokines, and proportion to the number of IgE level and eosinophils in the inflamed region.

The conjunctiva is a thin membrane that covers the eye. When an allergen irritates the conjunctiva, common symptoms that occur in the eye include: ocular itching, eye lid swelling, tearing, photophobia, watery discharge, and foreign body sensation. The allergen will trigger a typical allergic progress aforementioned. The study showed that patients limited certain activities such as going outdoors, reading, sleeping, and driving. Therefore, treating patients with allergic conjunctivitis can improve their everyday quality of life.

Atopy, or atopic syndrome, is an allergic hypersensitivity affecting parts of the body not in direct contact with the allergen. It may involve eczema (atopic dermatitis), allergic conjunctivitis, allergic rhinitis and asthma. There appears to be a strong hereditary component. Atopic syndrome can be fatal for those who experience serious allergic reactions such as anaphylaxis, brought on by reactions to food or environment. Although atopy has various definitions, most consistently it is defined by the presence of elevated levels of total and allergen-specific IgE in the serum of patient, leading to positive skin-prick tests to common allergens. Since the twentieth century, many mucosal inflammatory disorders have become dramatically more common; atopy is a classic example of such a disease. It now affects 10-20% of children and 1-3% of adults in industrialized countries, and its prevalence there has more than doubled in the past thirty years.

The Dendrobii Herba polysaccharides described herein can also be used to increase the population of T regulatory cells in the intestinal lamina propria site via, e.g., oral administration. The term "T regulatory cell" used herein refers to a specialized subpopulation of T cells that act to suppress activation of immune system and thereby maintain immune system homeostasis and tolerance to self antigens. Sometimes it also called suppressor T cells. T regulatory cells come in many flavors, including those that express the CD8 transmembrane glycoprotein (CD8+ T cells), those that express CD4, CD25 and Foxp3 (CD4+CD25+ regulatory T cells or "Tregs") and other T cell types that have suppressive function. In one embodiment, the T regulatory cells refer to the population which expressed CD4 and CD25.

The term "intestinal lamina propria" used herein refers to a thin layer of loose connective tissue which lies beneath the epithelium and together with the epithelium constitutes the mucosa. In this region, there are many immune cells retained here, for example, dendritic cells, macrophages, T cells, B cells or mast cells etc.

In another example, the polysaccharides also can be administrated to a subject to reduce the subject's IgE levels in serum and BALF. IgE plays a key role in the pathogenesis of allergy. Like other immunoglobulins, IgE is produced by B-lymphocytes following exposure of a foreign antigen from environment. When two or more molecules of IgE bound to the surface of a cell are simultaneously linked to its specific allergen, the cell will immediately release preformed inflammatory cytokines including histamine, which induce the immediate affects or early phase of allergy. These cytokines recruit eosinophils, macrophages and more basophils to the area. These newly synthesized substances and the cells they recruit are key players in the late phase of the allergic response. The close association between IgE, allergy, and asthma has long been recognized (Platts-Mills T A E, Am J Respir Crit Care Med, 164:S1-S5, 2001; Milgrom H, et al., N Eng J Med., 341:1966-73, 1999). In one embodiment, mice fed with the polysaccharides extracted from Dendrobii Herba had lower level of IgE in serum and in BALF. Also these mice had fewer eosinophils and cytokines or chemokines which attracted the immune cells and stimulate airway epithelium. Therefore, the polysaccharides extracted from Dendrobii Herba could treat asthma.

In yet another example, the polysaccharides are used to reduce airway-remodeling resulted from inflammation by orally administrating the subject with polysaccharides extracted from Dendrobii Herba.

The term "airway remodeling" used herein refers to structural changes that occur in conjunction with, or because of, chronic airway inflammation. Airway remodeling results in alterations in the airway epithelium, lamina propria, and submucosa, leading to thickening of the airway wall. Consequences of airway remodeling in asthma include incompletely reversible airway narrowing, bronchial hyper-responsiveness, airway edema, and mucus hypersecretion.

Without further elaboration, it is believed that one skilled in the art can, based on the above description, utilize the present invention to its fullest extent. The following specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever. All publications cited herein are incorporated by reference.

Example 1

Preparation of Polysaccharides from Dendrobii Herba

2 kg of fresh Dendrobii Herba was dried to form the dry material, and then the dry material was immersed and treated with 20 L of methanol to obtain a treated plant. The treated plant was treated with a de-methanol process, and then immersed in water overnight to obtain an overnight water solution. The overnight water solution was extracted with 24 L warm water at the temperature ranged 60.degree. C. for 30 min, and then centrifuged by the centrifuge (ER-RC13 C-124, HITACH) at 5,000 rpm and 10.degree. C. After the centrifugation, the supernatant was filtered through 6 .mu.m filter paper. The filtrate was precipitated with 50% (w/v) ethanol to obtain the polysaccharides.

Example 2

The Effect of Polysaccharides Extracted from Dendrobii Herba on Asthma

Set Up an Animal Model of Asthma

BALB/c male mice were randomly grouped into normal group (n=6, healthy mice as negative control), the control group (n=10, mice sensitized with OVA but without the treatment of the polysaccharides extracted from Dendrobii Herba), the treatment groups sensitized with OVA fed with a dose of 10 mg/kg/day (n=8), 30 mg/kg/day (n=8) and 90 mg/kg/day (n=8). Except the normal group, all the mice were immunized with an intraperitoneal injection of 20 and 50 .mu.g/ml OVA (Sigma, USA) in phosphate-buffered saline (PBS) combined with the 2 mg and 5 mg Al(OH).sub.3 as adjuvant on Day 1 and 14, respectively. Negative control mice were given intraperitoneal injection of 1.times.PBS on each immunization. All mice were exposed to 1% OVA in PBS for 20 min by ultrasonic nebulizer (Buxco) on Day 28, 29, 30. On Day 31, all mice were subjected to AHR (Airway hyperresponsiveness) test by various concentration of methacholine, and sacrificed the next day (the method was referred to Charles Perkins et al., J. Allergy Clin. Immunol., 118(2):410-419). On Day 0, 21 and after AHR test, bloods of the mice were collected from the retro-orbital venous plexus. The blood samples were tested for OVA-specific antibodies.

Determination of Airway Hyperresponsiveness to Methacholine

Mice were placed, unrestrained, in cylindrical plexiglass plethysmograph chambers that were connected to a Buxco nebulized control aerosol delivery system and a Buxco Max II apparatus for analyzing barometric plethysmography (Buxco Electronics, Sharon, Conn.). Baseline measurements of enhanced pause (Penh) were made over a 5-minute period. Penh, referring to a unit-less measure of airflow obstruction, reflects changes in pulmonary function related to quantitative differences in time and extent between inspiration and expiration. Specifically, Penh is considered a parameter that reflects changes in waveform of the measured box pressure signal that are a consequence of bronchoconstriction and is an index of airway obstruction. The severity of asthma can be evaluated by the level of Penh (Zhang et al., J. Allergy Clin. Immunol., February; 113(2):320-6, 2007).

Mice were then challenged for 3 minutes by means of inhalation of aerosolized, .beta.-methacholine in PBS produced with a nebulizer (Buxco Electronics, Sharon, Conn.), starting at a methacholine concentration of 6.25 mg/mL. Penh measurements were starting 3 minutes after completion of exposure to the aerosolized methacholine, and average Penh values for the 3-minute period were calculated. Subsequently, the procedure was then serially repeated and the concentration of methacholine was changed to 12.5 mg/mL and 25 mg/mL. All the recorded data were normalized to the baseline measurements, and the results of each group were showing in FIG. 1 (see Original Patent).

AHR contributes significantly to airway obstruction and the cardinal symptoms in asthma, such as breathlessness, chest tightness, coughing and difficultly speaking. Accordingly, inhibition of AHR can ease the severity of asthma. As shown in FIG. 1, all of the three treatment groups exhibited significantly decreased Penh responses to aerosolized 25 mg/mL methacholine compared to the control group. It was indicated that the polysaccharides extracted from Dendrobii Herba could inhibit AHR, therefore it could treat asthma.

Brochoalveolar Lavage Fluid (BALF) Analysis

"Brocho-alveolar lavage fluid" is the fluid obtained by washout of the alveolar compartment of the lung. It is used to determine biochemical and inflammatory changes in the interstitial lung tissue, thereby assessing the efficacy of the method of this invention.

After cervical dislocation, the trachea were exposed and incubated with a polyethylene catheter. BALF was collected from the mice by lavaging with 1 mL of PBS through the trachea. After the wash was centrifuged, the supernatant was used for antibody detection and a total cell count was obtained from the pellet. Cytospin slides were prepared and stained by Liu's staining, a modification of Giemsa staining (Sevens, M. L. Fundamentals of clinical hematology., W.B. Saunders company, 1997).

The cells of BALF from the mice were first stained by addition of 0.5 mL Liu's A solution (prepared by dissolving 0.18 g Eosin Y and 0.05 g Methylene blue in 100 mL methanol, followed by filtering the resultant solution through a No. 3 filter paper) for 30 seconds. Thereafter, 1 mL Liu's B solution (prepared by dissolving 0.12 g Methylene blue, 0.14 g Azure B, 2.52 g Na.sub.2HPO.sub.4 and 1.26 g KH.sub.2HPO.sub.4 in 100 mL H.sub.2O, followed by filtering the resultant solution through a No. 3 filter paper) was added to mix with the Liu's A stain immediately. After a reaction time of 60 seconds, the slide was washed with water to clean out the stain solution. The slide were air-dried and then examined under an optical phase microscope, and the differentials were obtained after counting 300 cells. The results were showed in FIG. 2 and FIG. 3 (see Original Patent).

As shown in FIG. 2, the number of total cells in 90 mg/kg/day group compared to the control group had significant decreased. Furthermore, the percentages of each cell type (eosinophils, neutrophils, monocytes and lymphocytes) are shown in FIG. 3. Eosinophil and lymphocyte percentages were significant reduced in the group orally treated with 90 mg/kg/day Dendrobii Herba polysaccharides compared to the control group.

Without being bound by theory, the polysaccharides obtained from Dendrobii Herba may be effective in treating asthma through the following mechanism. It has been reported that eosinophils play the key role in asthma development. See Walsh G. M., Curr Opin Hematol., 8(1):28-33, 2001; and Menzies-Gow A et al., J Asthma., 38(8):605-13, 2001. As shown above, the Dendrobium polysaccharides reduced numbers of eosinophils in the BALF, thereby alleviating asthmatic symptoms.

Effect of the Polysaccharides Extracted From Dendrobii Herba on Eosinophilia and Airway Remodeling in Lungs

After BALF was obtained, the lung tissue was fixed in 10% neutral buffered formalin for 24 h. The lung tissue was embedded in paraffin, and then cut into 5 .mu.m thickness sections. The slices were stained with H&E solution (hematoxylin; Sigma MHS-16 and eosin, sigma HT110-1-32). The results were photographed and showed in FIG. 4 (see Original Patent).

Asthma is characterized by a specific pattern of inflammation in the airway mucosa, and involves the infiltration of eosinophils, increased number of T.sub.H2 cells relative to T.sub.H1 cells. In addition, there are characteristic structure changes to the airway, termed remodeling, some of which might even precede the development of the disease. These structural changes seen in asthmatic patients can include thickening of the airway wall reticular basement membrane, formation of an abnormal elastic fiber network, alterations in airway cartilage structure, angiogenesis, and increase in airway smooth muscle mass.

In the present invention, control group obviously displayed the thickening of the airway epithelium basement and the narrowness in bronchial tubes. As the dose of Dendrobii Herba polysaccharides treatment went up, so the features of airway remodeling reduced and the diameter of bronchial tubes came to nature. Combination with the results in FIG. 2, the present invention features a method to decrease the number of eosinophil and lymphocyte, also relief the symptom of airway remodeling.

Oral Treatment of the Polysaccharides Extracted From Dendrobii Herba Can Increase the Percentage of Treg in Intestinal Lamina Propria

Mice were killed by cervical dislocation. The small intestine was immediately removed, and flushed in HBSS (with HEPES, Ca.sup.2+ and Mg.sup.2+-free). Peyer's patchs were carefully dissected out and cut into segments. To remove the epithelium cells, the segments were shaken with 1 mM dithiothreitol solution (DTT, Amresco, USA) and 1 mM ethylenediaminetetraacetic acid (EDTA, Sigma, USA) at 37.degree. C. for one hour. After the incubation, the segments were minced into 1-mm pieces and digested in RPMI 1640 (Gaithersburg, USA) contained with 30 unit/mL Collagenase Type I (Sigma, USA) and 10 unit/mL Collagenase Type II (Sigma, USA) as well as 10% fetal calf serum at 37.degree. C. for one hour. The digested tissue were passed through a nylon mesh (Small Parts, USA) to obtain the cells. After thorough washing, the mononuclear cells were obtained by the centrifugation on Percoll.

The mononuclear cells were adjusted to 1.times.10.sup.6 cells/mL, and added to the tube to incubated with FITC conjugated CD4 antibody (BD Biosciences, USA) and PE conjugated CD25 antibody (BD Biosciences, USA) for 30 min at 4.degree. C. in the dark. The samples were washed twice in cold PBS and analyzed by two-color cytometry performed with a FACScan (Becton Dickinson Bioscience, USA). The number of CD4+CD25+ cells divided by the number of CD4+ cell was the percentage of Treg. The results were shown in FIG. 5 (see Original Patent). Mice fed with 90 mg/kg/day Dendrobii Herba polysaccharides had more Treg in the intestinal lamina propria.

Effects of the Polysaccharides Extracted From Dendrobii Herba on the Serum and BALF Levels of OVA-specific IgE in the Mice Sensitized With OVA

The serum collected on Day 1, 14 and the day before sacrificed and BALF were used to detect the OVA-specific IgE by ELISA. The assay was performed according to the manufacture's direction. Serum samples in duplicate were diluted to 1:50 and BALF was not diluted. The antibody used here was AP conjugated goat-anti-mouse IgE bought from Southern BioTech (USA). As shown in FIG. 6, serum IgE significant decreased in 90 mg/kg/day Dendrobii Herba polysaccharides group. However, the IgE level of BALF was also on the downward trend in the same group.

Nowadays, many researches have indicated that IgE is the key molecules in immediate allergic reactions, because it can form a bridge between allergens and neutrophils and triggers cellular degranulation, with liberation of countless preformed mediators and cytokines (Holgate S et al., J Allergy Clin. Immunol., 115:459-465, 2005; Cooper P J, Parasite Immunol. 26:455-467, 2004; Milgrom H, et al., ut supra). Therefore, neutralization or inhibition of IgE synthesis could be a rational option for the treatment of allergic diseases (Sarinho E and Cruz A A, J Pediatr (Rio J), 82(5 Suppl):S127-32, 2006; Wagelie-Steffen A L et al., Clin Chest Med., 27:133-147, 2006; Clark J et al., J Asthma, 43:87-93, 2006). In the present invention, 90 mg/kg/day Dendrobii Herba polysaccharides could decrease the level of IgE in serum and in lungs of mice with asthma. In view of these data, Dendrobii Herba polysaccharides have great potential to treat allergic disease or asthma.

Effects of the Polysaccharides Extracted From Dendrobii Herba on the Gene Expression in Lung Tissue From the Mice Sensitized with OVA

The tissue was excision and cut into pieces. Total RNA was then isolated with rare RNA total RNA isolation reagent (Gsharp Corporation, Taiwan) according to the manufacture's direction. Reverse transcription used 5 .mu.g RNA for cDNA synthesis with MMLV reverse transcrptase (Promega, USA) in a total volume of 40 .mu.l. The portion of the resulting reverse-transcription product (1 .mu.l) was used to PCR amplification. The primer sequences used for IL-13, eotaxin-1, IDO, IL-17, and TSLP were listed as following -- see Original Patent.

PCR conditions to amplify these genes were 95.degree. C. for 5 min for initial degeneration and followed by 94.degree. C. for 30 sec, 58.degree. C. for 30 sec and 72.degree. C. for 1 min. All of the gene expression level was normalized with .beta.-actin mRNA. As shown in FIG. 7, the expression level of mRNA of cytokine or chemokine in lungs were lower in the group fed with 30 mg/kg/day and 90 mg/kg/day polysaccharides extracted from Dendrobii Herba.

Selective recruitment of eosinophils by some chemokines, such as IL-13, eotaxin-1, IL-17 and TSLP, into the airways during allergic inflammation suggests that eosinophil-specific chemoattractant are produced and released throughout the course of pulmonary inflammation (Rothenberg M E., N. Engl. J. Med., 338:1592-1600, 1998; Lacy P et al., Chem. Immunol., 76:134-155, 1998). Furthermore, it is acknowledged that an increase of IDO, which was induced by eosinophils, will lead to the apoptosis of Th1 and promote Th2 polarization. In the result, eosinophil may maintain Th1-Th2 imbalance seen in allergic asthma through expression functionally active IDO in lymphoid tissue (Odemuyiwa S O et al, J Immunol. Nov. 15, 2004; 173(10):5909-13). Therefore, inhibition of these protein of production is helpful to block the progression of asthma. In the present invention, mice with oral treatment of the polysaccharides from Dendrobii Herba had lower gene expression level mentioned above, which were related to recruit eosinophils or lymphocytes. Because these two cells played the major role in the process of allergic disease, especially asthma, reduced the chemokine could prevent the infiltration in the lungs. Consequently, the symptoms of allergic disease associated to eosinophil, such as asthma can be treated.

Claim 1 of 20 Claims

1. A method for treating an allergic disease, comprising administering to a subject in need thereof an effective amount of polysaccharides obtained from Dendrobii Herba.
 

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