| LICENSEE | This data is not available for free |
| LICENSOR | This data is not available for free |
| LITERATURE REF. | This data is not available for free |
| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | June 20, 2000 |
| PATENT TITLE |
Selective inhibition of cyclooxygenase-2 |
| PATENT ABSTRACT | Disclosed is a method for selectively inhibiting cyclooxygenase-2 in an animal having a cyclooxygenase-2 activity by delivering into the animal an amount of a conjugated linoleic acid effective to reduce cyclooxygenase-2 activity in the animal |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | July 20, 1999 |
| PATENT REFERENCES CITED |
Kim et al., Han'guk Sikp'um Yongyang Kwahak Hoechi, 26(5), 972-977 (abstract), 1997. Cowley, Geoffrey "Getting a Grip on Pain," Newsweek (Dec. 14, 1998). Hamberg, M., "Oxidation of Octadecatrienoic Acids in the red Alga Lithothamnion corallioides: Structural and Stereochemical Studies of Conjugated Tetraene Fatty Acids and Bis Allylic Hydroxy Acids," J. Chem. Soc, Perkin Trans. 1:3065-3072 (1993). Hayek, et al., "Dietary Conjugated Linoleic Acid Influences the Immune Response of Young and Old C57BL/6NCrIBR Mice," J. Nutr. 129:32-38 (1999). Li, et al., "Conjugated Linoleic Acids Alter Bone Fatty Acid Composition and Reduce ex vivo Prostaglandin E2 Biosynthesis in Rats Fed n-6 or n-3 Fatty Acids," Lipids 33:417-425 (1998). Liu et al, "Conjugated linoleic acid reduces arachidonic acid content and PGE2 synthesis in murine keratinocytes," Cancer Letters 127:15-22 (1998). Nugteren, I.H., "Inhibition of Prostaglandin Biosynthesis by 8CIS, 12TRANS, 14CIS-Eicosatetraenoic Acid," Chimica Et Biophysica Acta 210:171-176 (1970). Proceedings, "The International Symposium Eicosanoids, Aspirin and Asthma," (Web Document, last updated Jul. 21, 1998). Reilly, Joseph, "Nonsteroidal Anti-inflammatory Drugs: An Essential Class of Drugs Revisited," (Web Document, NY State Council of Health-System Pharmacists 1998). Simmons et al., P.N.A.S. U.S.A. 86:1178-1182 (1989). Sugano et al, "Lymphatic recovery, tissue distribution, and metabolic effects of conjugated linoleic acid in rats," J. Nutritional Biochem. 8:38-43 (1997). Sugano et al., "Conjugated Linoleic Acid Modulates Tissue Levels of Chemical Mediators and Immunoglobulins in Rats," Lipids 33:521-527 (1998). Williams, et al., "Prostaglandin endoperoxide synthase: Why two isoforms?" Am. J. Physiol. 270 (Gastrointest. Liver Physiol. 33):G393-G400 (1996). Li, Y. et al., "Dietary Conjugated Linoleic Acids Alter Serum IGF-I and IGF Binding Protein Concentrations and Reduce Bone Formation in Rats Fed (n-6) 0r (n-3) Fatty Acids," J. Bone Miner. Res. 14:1153-1162 (1999). |
| PATENT CLAIMS |
We claim: 1. A method for selectively inhibiting cyclooxygenase 2 activity in an animal having cyclooxygenase 2 activity, comprising the step of: administering to the animal an amount of a conjugated linoleic acid (CLA) effective to reduce the activity of cyclooxygenase 2. 2. The method of claim 1, wherein the administering step comprises a method selected from the group consisting of oral delivery, intramuscular injection, intravenous injection, transdermal delivery, and transmucosal delivery. 3. The method of claim 1, wherein the administering step comprises oral delivery. 4. The method of claim 1, wherein the animal is a human. 5. The method of claim 1, wherein the conjugated linoleic acid is selected from the group consisting of an 18:2(9c,11t) isomer, an 18:2(9t,11c) isomer, an 18:2(10c,12t) isomer, an 18:2 (10t,12c) isomer, a bioactive ester thereof, a salt thereof, and a mixture thereof. 6. The method of claim 1, wherein the CLA is delivered in a dosage of between about 1 mg/kg and 1000 mg/kg body weight of the animal. 7. A method for reducing cyclooxvyenase 2-mediated inflammation in an animal comprising the step of delivering into the animal an amount of a conjugated linoleic acid effective to reduce the inflammation without causing gastric irritation. -------------------------------------------------------------------------------- |
| PATENT DESCRIPTION |
BACKGROUND OF THE INVENTION Inflammatory reactions and associated pain can be induced by prostaglandins. Inflammation can be reduced by inhibiting prostaglandin biosynthesis. Most non-steroidal anti-inflammatory drugs (NSAIDs), including aspirin, inhibit prostaglandin synthesis by inhibiting cyclooxygenase, a key regulated enzyme in synthesis of 20 carbon eicosenoids, including prostaglandin E2 (PGE.sub.2), from arachidonic acid. However, complete inhibition of prostaglandin synthesis is disfavored because prostaglandins also beneficially maintain the digestive tract lining. In the absence of prostaglandins, a propensity for ulcers and similar digestive problems can develop. This is particularly problematic for people suffering from conditions such as arthritis, the treatment of which generally requires long-term use of relatively large doses of anti-inflammatory agents. The cyclooxygenase enzymes are reviewed by Williams, C. S. and R. N. DuBois, "Prostaglandin endoperoxide synthase: Why two isoforms?" Am. J. Physiol. 270 (Gastrointest. Liver Physiol. 33):G393-G400 (1996), incorporated herein by reference in its entirety. Briefly, cyclooxygenase exists in at least two different enzyme isoforms (Simmons et al., P.N.A.S. U.S.A. 86:1178-1182 (1989)), designated-Cox-1 and Cox-2. Cox-1 is involved in synthesizing housekeeping prostaglandins that function to maintain the digestive tract lining. In contrast, Cox-2 catalyzes the synthesis of prostaglandins that cause inflammation and pain, but does not appear to catalyze housekeeping prostaglandins. Both Cox-1 and Cox-2 are involved in producing precursors for several prostanoids including PGE.sub.2. Cox-1 is expressed constitutively at relatively stable levels in many tissues, whereas Cox-2 expression can be induced by a variety of chemicals, including, but not limited to, lipopolysaccharides, phorbal esters, interleukin-1, tumor necrosis factor, human chorionic gonadotropin, and platelet activating factor. As a result of this distinction, one can characterize the relative contribution of each isoform to the overall PGE.sub.2 level by comparing basal PGE.sub.2 levels to the levels after induction. Because existing drugs that bind both Cox-1 and Cox-2 can cause significant undesired gastric side effects, considerable attention has been directed toward developing pain relief medications that specifically inhibit Cox-2 enzyme activity without affecting Cox-1 enzyme activity. Recently, the Food and Drug Administration approved one such medication, Celebrex, only for the treatment of arthritis pain, pending further studies. Preliminary results suggest that Celebrex provides pain relief and reduces inflammation without causing stomach problems. Unfortunately, Celebrex is expensive. Accordingly, there is currently a strong interest in developing pharmaceuticals and therapies that reduce inflammation and provide pain relief without causing associated stomach problems. Conjugated linoleic acid reduces liver and serum PGE.sub.2 levels in rats fed a diet containing 1% CLA (Sugano, et al. Nutritional Biochem. 8:38-43, 1997). Liu et al. (Cancer Lett. 127:15-22, 1998) suggested that CLA inhibits PGE.sub.2 synthesis by cyclooxygenase by competing with the enzyme's substrate, arachidonic acid. It was not known whether conjugated linoleic acids inhibit both Cox-1 and Cox-2. BRIEF SUMMARY OF THE INVENTION The present invention is a method of selectively inhibiting Cox-2 in an animal expressing Cox-2, the method comprising the step of administering to the animal a conjugated linoleic acid in an amount effective to selectively reduce the activity of Cox-2 without substantially reducing the activity of Cox-1. Selective reduction of Cox-2 activity can be assessed by comparing levels of PGE.sub.2 before and after inducing Cox-2 expression, as described herein. It is an object of the present invention to selectively reduce the activity of Cox-2 enzyme without substantially reducing the activity of Cox-1. It is an advantage of the present invention that conjugated linoleic acid is generally regarded as safe and non-toxic when administered to animals and humans. It is another advantage of the present invention that conjugated linoleic acid can be obtained and used without prescription. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS FIG. 1 shows the magnitude and time course of prostaglandin E.sub.2 (PGE.sub.2)release from superfused trachea of sensitized guinea pigs fed a control diet (diamonds) or a diet containing 0.25% CLA (squares) before (collection period 0) and after (periods 1-8) antigen challenge. FIGS. 2A-2C shows the release of PGE.sub.2 from lung (A), bladder (B), and trachea (C) tissue from sensitized guinea pigs with or without (basal) antigen challenge. DETAILED DESCRIPTION OF THE INVENTION The inventors have recognized, and disclose herein, that conjugated linoleic acid (CLA) selectively inhibits Cox-2 enzyme activity without significantly reducing Cox-1 enzyme activity in animals administered an amount of CLA effective to inhibit Cox-2 enzyme activity. This observation was not previously noted, and permits advantageous therapeutic interventions that satisfy a stated object of the present invention. The observation is important because the housekeeping functions of Cox-1 are maintained without adverse effect, while the inflammatory response and pain associated with Cox-2-directed prostaglandin synthesis can be controlled. Accordingly, one aspect of the present invention is a method for selectively inhibiting cyclooxygenase 2 (Cox-2) in an animal expressing Cox-2, the method comprising the step of administering to the animal an amount of at least one conjugated linoleic acid isomer effective to selectively reduce the activity of Cox-2 without substantially affecting cyclooxygenase 1 (Cox-1) activity. The absolute percent reduction of Cox-2 activity is less critical than the in vivo effects caused by reduced Cox-2 activity. What is important is that CLA inhibits Cox-2 activity to an extent sufficient to reduce inflammation, without causing stomach problems. The effect is most readily studied in an ex vivo model system, although by carefully selecting an appropriate model system, namely guinea pigs, one can reasonably predict success in mammals, including humans and domesticated animals such as farm animals and pets. In the model system, Cox-2 activity is preferably reduced by at least about 10% in tissue from animals fed a diet containing CLA. More preferably, Cox-2 activity is reduced by 20% or even 50% or more. At the same time, Cox-1 activity is reduced insignificantly. The effect of CLA on cyclooxygenase activity can also be expressed as the percentage ratio of the Cox-2:Cox-1 reduction. Preferably, the percentage ratio is maximized so as to afford effective pain relief and reduced inflammation, without interfering with the maintenance functions of Cox-1. Preferably, this ratio is at least about 2:1. More preferably, this ratio is at least about 20:1, or even about 50:1. In this application "conjugated linoleic acid" or "CLA" means an unsaturated fatty acid having 18 carbons and two conjugated double bonds, the fatty acid being selected from the group consisting of 18:2(9c,11t), 18:2(9t,11c), 18:2(10c,12t) and 18:2 (10t,12c), and also including bioactive esters and salts thereof, and mixtures thereof. The CLA may be administered by any convenient means. Preferably, the conjugated linoleic acid is delivered orally in a capsule, tablet, or chewable form comprising conjugated linoleic acid and a pharmaceutically acceptable ingestible carrier. It is envisioned that the CLA can be administered orally for timed-release delivery. Alternatively, the CLA may be formulated for intravenous, intramuscular, transdermal, or transmucosal administration. Since CLA is generally regarded as safe, the precise amount of CLA administered is not considered critical, as long as it is sufficient to achieve a stated object of the invention. For example, if fed to an animal, an appropriate amount of CLA in the diet is in the range of 0.1% to 5% by weight, preferably 0.2% to 0.5% by weight in the diet. If administered by another route, CLA can be effectively administered at a dosage ranging from about 1 mg/kg to about 1000 mg/kg body weight of the animal or higher. This corresponds to about 0.1 g/day to about 40 g/day for a person weighing 45 kg. In the following non-limiting examples, Cox-1 and Cox-2 activity were measured indirectly by monitoring the levels of PGE.sub.2 released from excised tissue of sensitized animals fed CLA or CLA-free diets, in the presence or absence of an inducing antigenic challenge. The examples demonstrate that the method of the present invention is effective in reducing Cox-2 directed PGE.sub.2 production in guinea pigs, a preferred model system for evaluating immune and inflammatory responses in mammals, including humans. Since the chemical structure of COX-2 substrates are the same in all animal species, it is reasonably predicted from these trials that the method of the present invention will achieve selective inhibition of Cox-2 in any animal having the Cox-2 isoform, including in humans. PGE.sub.2 levels were measured in excised tissue from guinea pigs fed (or not fed) CLA and sensitized to an antigen using tracheal superfusion or tissue baths containing lung, bladder, or tracheal tissue. One wishing to monitor Cox-2 response to CLA could alternatively measure the amount of Cox-2 protein or Cox-2 mRNA formed in appropriate tissues. In the absence of an inducing antigen challenge, tissue from CLA-fed animals exhibits only slight decreases in PGE.sub.2 production, relative to animals fed a CLA-free control diet. In contrast, in tissue subjected to inducing antigen challenge, much greater PGE.sub.2 reduction was observed in tissue from animals fed CLA in the diet than in tissue from animals fed CLA-free diets. These results suggest that the CLA specifically inhibits the inducible Cox-2 enzyme activity to a much greater extent than it inhibits the constitutively expressed Cox-1 enzyme activity. |
| PATENT EXAMPLES | This data is not available for free |
| PATENT PHOTOCOPY | Available on request |
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