MEDICINAL COMPOSITION FOR CURING THROMBOCYTOPENIA

Abstract: It has been revealed that human interleukin-15 (hIL-15) acts on the megakaryocyte-thrombocyte system to accelerate its differentiation, maturation and/or proliferation, thereby accelerating the formation of thrombocytes. The present invention provides a medicinal composition effective for curing or preventing diseases derived from thrombocytopenia and diseases accompanied by thrombocyte dysfunctions.

Description: The present invention relates to the use of human interleukin-15 for the preparation of a pharmaceutical composition for curing thrombocytopenia. The active ingredient human interleukin-15 (to be described hereinafter as "hIL-15") has activity to promote the differentiation, maturation and/or proliferation of megakaryocyte-thrombocyte cells and the production of platelets through actions on the cells. Since hIL-15 of this invention acts on the megakaryocyte-thrombocyte system to accelerate the differentiation, maturation and/or proliferation thereof to thereby accelerate the formation of thrombocytes, it is useful especially in the field of medical care as an active ingredient of therapeutic and preventive agents for thrombocytopenia and for thrombocytopenic purpura associated with chemotherapy and bone marrow transplantation and for various diseases with tendency for bleeding attributable to thrombocytopenia and the like. Blood, which is an indispensable medium for somatic cells constituting the living body, contains blood cells such as erythrocytes, leucocytes, lymphocytes, and thrombocytes, and the like as tangible components. These cells have their own functions and contribute to the maintenance of homeostasis of the living body. It has been a longtime subject of research in the field of hematology to clarify the essential features of differentiation, maturation and proliferation of the blood cells in vivo. It has become recently apparent that the various blood cells are differentiated and maturated from one type of a multi-functional hematopoietic stem cell of the bone marrow and various types of humoral factors in vivo participate in the processes of differentiation and maturation. From these findings, the humoral factors are expected to be used as a medicament for curing diseases with decreases in blood cells, and the like. Until now there were found various humoral factors including erythropoietin (EPO), G-CSF, GM-CSF, M-CSF, and interleukin (IL) and some of them have been used practically as medical agents which are capable of promoting the differentiation and maturation of blood cells such as erythrocyte, leucocyte, lymphocyte lines, or the like. Thrombocytes are akaryocytes with diameters of 2-3 µm present in the blood and one of the tangible components in the blood, which play an important role in arrest of hemorrhage and formation of thrombus in vivo . It has become apparent that megakaryoblasts are formed within the bone marrow from multi-functional hematopoietic stem cells via megakaryocytic precursor cells to mature to megakaryocytes and the cytoplasm of the megakaryocytes is tragmented to form thrombocytes, which are released into the blood. Recently, various results of researches on the megakaryocyte-thrombocyte system have been reported. For example, it has been reported that IL-6 has activity to promote the maturation of megakaryocytes, which are precursor cells of thrombocytes [Ishibashi T. et al., Proc. Natl. Acad. Sci. USA 86 , 5953-5957 (1989), Ishibashi T. et al., Blood 74 , 1241-1244 (1989)]. According to the research works conducted so far, it is considered that two factors that act differently contribute to the formation of megakaryocyte colonies from bone marrow cells [Williams N. et al., J. Cell. Physiol., 110 , 101 (1982)]. The report shows that one is a megakaryocyte colony stimulating factor, Meg-CSF, which forms the megakaryocyte colonies by itself, while the other is a megakaryocyte potentiating factor, Meg-POT, which does not have activity to form megakaryocyte colonies by itself, but has activity to increase the number of megakaryocyte colonies and to promote the maturation of the colonies in the presence of the Meg-CSF. For example, IL-3 [Teramura M. et al, Exp. Hematol., 16 , 843 (1988)] and granulocyte-macrophage colony stimulating factor [Teramura M. et al, Exp. Hematol., 17 , 1011 (1989)], and the like were reported as factors having Meg-CSF activity in humans while IL-6 [Teramura M. and Mizoguthi H., Int. J. Cell Cloning, 8 , 245 (1990)], IL-11 [Teramura M. et al, Blood, 79 , 327 (1992)] and erythropoietin [Bruno E. et al., Blood, 73 , 671 (1989)], and the like were reported as factors having Meg-POT activity in humans. However, it is known that most of these factors are not factors that specifically act on the megakaryocyte-thrombocyte system but that express their effects through actions on other cells of the blood system or cells not belonging to the blood cell system. Thus, there is a risk that not only the expected actions but also other actions would be effected when these factors are administered as medical agents in anticipation of the actions on the megakaryocyte-thrombocyte system. For example, the above-described IL-6 has various actions other than those mentioned above. From the fact that IL-6 is deeply involved in induction of inflammation as an acute phase reactive protein in vivo , there may be a risk of severe side effects if it is used as a medical agent as it is. Recently, the c-Mpl ligand has been reported to have both weak Meg-CSF and strong Meg-POT activities [dc Sauvage F.J. et al., Nature, 369 , 533 (1994), Kaushansky K. et al., Nature, 369 , 568 (1994)]. However, because of the paucity of findings on the actions of the c-Mpl ligand, the practicability of this substance as a medical agent is still unknown. Thus, as far as factors acting on the megakaryocyte-thrombocyte system are concerned, it is important to find out biologically active substances that strongly act on the megakaryocyte-thrombocyte system and have high activity to promote its differentiation, maturation and/or proliferation. The development of such biologically active substances has been strongly demanded in the art. Under these circumstances the present inventors devoted themselves to studying novel biologically active substances which act on the megakaryocyte-thrombocyte system and show an activity to promote the differentiation, maturation and/or proliferation of the megakaryocyte-thrombocyte system and the formation of thrombocytes. As a result, IL-15 was found to have such activity and the invention was completed. IL-15 is a protein with a molecular weight of ca.14000 purified by Grabstein et al. [Science, 264 , 965, (1994); WO95127722] from a culture supernatant of an epithelial cell line, CV-1/EBNA, derived from the kidney of the African green monkey, Cercopithecus sabaeus, by using its ability to support the proliferation of a mouse T cell line, CTLL-2, as an index. Isolation of the gene revealed that a mature protein with 114 amino acid residues was formed by cleavage of a precursor with 162 amino acid residues. It is expressed well in placenta, monocytes of peripheral blood and skeletal muscle, while it is also expressed weakly in heart, lung, liver, and kidney, and the like. As to the biological activities of IL-15, there is a report describing its actions to support differentiation and proliferation of T and B cells, to activate NK cells, and to induce CTL and LAK activities. Accordingly, the substance is considered to be a cytokine involved mainly in immunization processes such as proliferation, differentiation, and activation of lymphocytes. WO95127722 discloses the use of IL-15 in pharmaceutical compositions poviding anti-tumor and anti-infectious disease immunity. An object of the present invention is to use hIL-15 for the preparation of a pharmaceutical composition for curing thrombocytopenia or for curing or preventing diseases derived from thrombocytopenia and diseases accompanied by thrombocyte dysfunctions. To achieve the above object, it is provided a pharmaceutical composition for curing thrombocytopenia characterized by comprising hIL-15 as an active ingredient. In the following this invention will be described in detail. In the context of the present invention it was found that hIL-15 has an activity to act on the rodent megakaryocyte-thrombocyte system and promote the production of acetylcholinesterase (to be described as "AchE" hereinafter). Since acetylcholinesterase is an enzyme that is produced in association with differentiation and/or maturation of rodent megakaryocytes [Acta. Haematol. JPN., 49 , 1688-1695 (1986)], the activity to promote the production of AchE mentioned above indicates the action of hIL-15 on the megakaryocyte-thrombocyte system. In the context of the present invention hIL-15 was found to have activity on the megakaryocyte-thrombocyte system. The activity on the megakaryocyte-thrombocyte system used herein means the ability to promote the differentiation and maturation of the megakaryocytes or its precursor cells, or the ability to promote the formation of thrombocytes in the processes of formation of thrombocytes from megakaryocytes. To measure the above-mentioned activity of hIL-15 of the present invention on the megakaryocyte-thrombocyte system, the method using bone marrow cells or megakaryocytic cells which comprises allowing the test substances on these cells to measure the appearance of proteins or enzymes specific to megakaryocytes or thrombocytes may be suitably used. Since rodent megakaryocytes produce AchE accompanied with their differentiation and maturation, the above-mentioned activity of biologically active substances on the megakaryocyte-thrombocyte system can be measured by, for example, counting the number of cells producing AchE by staining the cells or measuring the activity of AchE produced with a spectrophotometer [Toshiro Nagasawa et al., Acta Haematologica Japonica, 49 , 1688-1695 (1986)]. As will be mentioned below, it became apparent from the results of measuring the activity by the above method that hIL-15 acted on megakaryocytes to promote the production of acetylcholinesterase, and to promote the differentiation and maturation of the megakaryocyte cells to form thrombocytes. In addition, by conducting the megakaryocyte colony assay [Metcalf D. et al., Proc. Natl. Acad. Sci. U.S.A., 72, 1744 (1975)], it was found that hIL-15 alone showed activity to produce megakaryocyte colonies (Meg-CSF activity). In the following the pharmaceutical composition for curing thrombocytopenia will be described. The pharmaceutical composition is characterized by comprising hIL-15 as an active ingredient. As hIL-15, the full length natural amino acid sequence or a part of the sequence in an appropriate site of the molecule can be used. The pharmaceutical composition containing hIL-15 which has been subjected only to pharmaceutically necessary processing such as lyophilization, or sterilization by filtration can fully exert its effect. As a matter of course, pharmaceutically acceptable auxiliary components can be added if necessary to make pharmaceutical preparations using ordinary methods. Not only natural hIL-15 but also recombinant hIL-15 can be used. Various cells, either procaryotic or eucaryotic, can be used as a host for the production of recombinant hIL-15. For examples, Eschericia coli and mammal cells are preferably used. The auxiliary components include bases, stabilizers, antiseptics, preservatives, emulsifiers, suspending agents, solvents, solubilizers, lubricants, correctives, colorants, aromatics, soothing agents, vehicles, binders, thickeners (viscosity increasing agent), and buffers, and the like. Specified examples thereof inlcude calcium carbonate, lactose, sucrose, sorbitol, mannitol, starch, amylopectin, cellulose derivatives, gelatin, cacao butter, distilled water for injection, sodium chloride solution, Ringer solution, glucose solution, human serum albumin (HSA),and the like. In order to prepare the pharmaceutical composition using the above auxiliary components, suitable components may be selected and used referring to the List of Pharmaceutical Excipients (published by the Medical Regulatory Affairs Committee of the Pharmaceutical Manufacturers' Association of Tokyo and Medical Regulatory Affairs Committee of Osaka Pharmaceutical Manufacturers Association). The amount of 'auxiliary components may be chosen within a pharmaceutically acceptable range depending on the form of the pharmaceutical composition and the like. The dose of the pharmaceutical composition may be determined depending on the state, age, sex, and body weight of the patients. The method of administration may be chosen depending on the state of the patients from various methods of administration such as oral, intramuscular, intraperitoneal, intradermal, subcutaneous, intravenous, intraarterial, or rectal administration. The pharmaceutical composition is useful for therapeutic and preventive agents of thrombocytopenia and thrombocytopenic purpura accompanied with chemotherapy or bone marrow transplantation, various diseases with hemorrhagic tendency attributable to thrombocytopenia, and patients with malfunction of blood megakaryocytes and/or thrombocytes. Fig.1 depicts the induction of AchE activity by hIL-15. Fig.2 depicts the induction of AchE activity by hIL-15. Fig.3 depicts the induction of AchE activity by IL-3. Fig.4 depicts the induction of AchE activity by IL-11. Fig.5 depicts the induction of AchE activity by IL-15 in the presence of IL-3. In the following the present invention will be described in detail with reference to the examples, but is not construed to be limited to these embodiments. Abbreviations commonly used in the art will be used partly in the following description. Example 1: Measurement of Acetylcholinesterase Activity (in the absence of IL-3). To 100 µl of bone marrow cells of the mouse (C57BL/6N strain, 11-15 weeks of age) diluted to 1x10 6 cells/ml with "RPMI 1640" (Gibco Co.) supplemented with " 1 % 'Nutridoma · SR' " (Boehringer Mannheim Co.) (to be called in the following as "culture medium A") were added each 50 µl of the sample [hIL-15 (Pepro Tech Co./catalog No. 200-15) dissolved in culture medium A to a predetermined concentration, human IL-11 (Pepro Tech Co.) dissolved in culture medium A to a predetermined concentration as negative control, and mouse IL-3 (Boehringer Mannheim Co.) dissolved in culture medium A to a predetermined concentration as positive control]. The total amount of 150 µl was cultured in a 96-well culture plate (Corning Co.) at 37°C and 100 % humidity, in 5% CO 2 /95% air. At the 6th culture day 50 µl of of a solution containing "0.265 mM DTNB (Sigma Co.), 1% Triton X-100, 1M Tris-HCl (pH 7.2)" were added to the culture and its absorbance (to be called as "absorbance A") was measured at 415 nm. Fifty µl of 3 mM acetylthiocholine iodide were further added. After allowing to stand for 30 minutes at room temperature, the absorbance of this solution (to be called as "absorbance B) was measured at 415 nm. The value of "absorbance B" - "absorbance A" was regarded as AchE activity. Figs. 1-4 depict the results. The abscissa shows the concentrations of each IL at the time of culturing on the 96-well culture plates, while the ordinate depicts the AchE activity mentioned above ("absorbance B" - "absorbance A"). In Fig. 1 the closed circles represent the data obtained with IL-15 and the closed triangles those obtained with IL-11 used as a negative control. Fig.2 depicts the data obtained with IL-15 with concentrations different from those used in Fig. 1. Fig. 3 depicts the data obtained with IL-11 as a negative control with concentrations different from those used in Fig. 1. Fig. 4 depicts the data obtained with IL-3 alone as a positive control. In the absence of IL-3, IL-15 showed the activity to induce AchE activity equal to or even greater than that of IL-3 in mouse bone marrow cells, which means that IL-15 was capable of differentiation and maturation of megakaryocytic cells derived from mouse bone marrow cells. Example 2: Measurement of Acetylcholinesterase Activity (in the presence of IL-3). The experiments were conducted in the same manner as in Example 1 except that recombinant mouse IL-3 (Boehringer Mannheim Co.) was added to a final concentration of 0.75 ng/ml (0.5 ng/ml at the time of culture) to 100 µl of mouse bone marrow cells diluted to 1x10 6 cells /ml with "RPMI 1640" supplemented with 1% "Nutridoma · SR". As described above, IL-11 is known to exhibit Meg-Pot activity in the presence of a Meg-CSF, namely IL-3. Thus, different from Example 1, IL-11 represents a positive control in 'this example. Fig. 5 depicts the results. The abscissa depicts the concentrations of each IL at the time of culturing on the 96-well culture plates, while the ordinate depicts the above-mentioned AchE activity ("absorbance B" - "absorbance A"). In Fig. 5, closed circles represent the data obtained with IL-15, while the closed triangles represent those obtained with IL-11 used as a positive control. IL-15 was found to have activity to induce AchE in mouse bone marrow cells even in the presence of IL-3. Thus, it became apparent that IL-15 had ability to differentiate and maturate megakaryocytic cells derived from mouse bone marrow cells even in the absence of IL-3. Example 3. Megakaryocyte Colony Assay Using mouse bone marrow cells experiments were conducted with the monolayer soft agar culture method. 0.2 ml of horse serum (treated at 56 °C for 30 minutes, Biocell Co.), 0.1 ml (2 x 10 6 /nuclear cells) of bone marrow cells from thigh bone of the mouse (C57BL/6N strain male, 6-12 weeks of age), 0.2 ml of "Iscove's Modified Dulbecco's culture medium" (IMDM), 0.4 ml of "Modified McCoy's 5A culture medium" containing 0.75 % agar and 0.1 ml of an IL-15 solution [IL-15 (Pepro Tech Co./catalog No. 200-15) was dissolved in IMDM to 100 ng/ml] were mixed together, poured into a plastic tissue culture dish of 35 mm diameter and solidified. Culturing was conducted at 37 °C and 100 % humidity, in 5% CO 2 /95 % air. At the 6th culture day whole cultured material taken out together with the agar layer was placed on a slide glass and dried to a film-like preparation. The preparation was fixed with 5 % glutaraldehyde. AchE staining and counting of the number of megakaryocyte colonies were conducted by the method of Nakeff et al.[Proc. Soc. Exp. Biol. Med., 151 , 587 (1976)]. Conglomerates containing more than 4 AchE staining positive cells were regarded as a megakaryocyte colony. The magnification of the microscope was set at 200-fold. As a result, 30 megakaryocyte colonies were observed when hIL-15 was added to the culture medium to a final concentration of 10 ng/ml. Only 2 megakaryocyte colonies were found in experiments conducted under the same condition except that no hIL-15 was present. These findings indicate that hIL-15 alone has an activity to proliferate megakaryocytic cells. By revealing that hIL-15 acts on the megakaryocyte-thrombocyte system to accelerate its differentiation, maturation and/or proliferation, thereby accelerating the formation of thrombocytes, it is provided a pharmaceutical composition comprising hIL-15 as an active ingredient which is effective for curing thrombocytopenia or for curing or preventing diseases derived from thrombocytopenia and diseases accompanied by thrombocyte dysfunctions.

Claims: Use of human interleukin-15 for the preparation of a pharmaceutical composition for curing thrombocytopenia, or for curing and preventing diseases derived from thrombocytopenia and diseases accompanied by thrombocyte dysfunction.

Inventors: SHIMONAKA YASUSHI, SHIMONAKA, YASUSHI
Applicants: CHUGAI PHARMACEUTICAL CO LTD, CHUGAI SEIYAKU KABUSHIKI KAISHA
Application year: 1996
Main classification: A61K38
IPC codes: C07K14, A61K38