Patent Publication Number: US-2021162018-A1

Title: Pharmaceutical composition for prevention or treatment of preterm birth

Description:
The present disclosure relates to a pharmaceutical composition for the prevention or treatment of preterm birth, and in particular, to a pharmaceutical composition capable of preventing preterm birth by inhibiting an increase in a muscle-collagen ratio in proximal cervix. 
     BACKGROUND OF THE INVENTION 
     A ratio of preterm birth in pregnancy is 10%, and a preterm birth rate tends to increase every year. In addition, preterm birth is the most important cause of neonatal mortality, which affects a low birthrate and a decrease in population. 
     A history of preterm birth, a short cervix length, multiple pregnancy, elderly pregnancy, infectious diseases, chronic diseases, etc. are known as risk factors for preterm birth, and measurement of the length of the cervix using ultrasound is used as an early predictive test for preterm birth. 
     Progesterone, Nifedipine, Prometrium, Makena (hydroxyprogesterone caproate), etc. are used as a preventive or therapeutic agent for preterm birth. Among these, progesterone, which is the most widely used, prevents preterm birth by preventing uterine contraction and preterm labor, and has a prophylactic effect for pregnant woman with a short cervix or a history of preterm labor. However, the progesterone has not been proven to be effective for preterm birth caused by causes other than those described above, and cannot be used for a patient with a history of breast cancer, abnormal liver function, or venous thrombosis. Also, all of the existing therapeutic agents for preterm birth are taken after pregnancy when it is diagnosed that a preterm birth has a high risk, and there are not known therapies and drugs that may be taken before pregnancy to lower the risk of preterm birth in advance. 
     Thus, there is a need for a therapeutic agent that may act as a pharmacological mechanism different from the conventional therapeutic agent for preterm birth, and may be taken before pregnancy to lower the risk of preterm birth in advance. 
     PRIOR ART DOCUMENT 
     Patent Document 
     
         
         (Patent Document 1) Korea Patent Application Laid-open No. 10-2017-0125708 (Nov. 15, 2017) 
       
    
     A pharmaceutical composition according to an embodiment may lower the risk of preterm birth. 
     A pharmaceutical composition according to an embodiment may be administered after cervical surgery to recover the damaged cervix, thereby lowering the risk of increased preterm birth. 
     SUMMARY OF THE INVENTION 
     An aspect of the present disclosure provides a pharmaceutical composition for the prevention or treatment of preterm birth, comprising, as an active ingredient, an agent that inhibits the differentiation of fibroblasts into myofibroblasts in cervix. 
     The present inventors found that the risk of preterm birth may increase if a muscle-collagen ratio increases due to an increase in the differentiation of myofibroblasts in proximal site during a regeneration process after injury such as a wound occurred in the cervix, and confirmed that a drug capable of inhibiting the risk of preterm birth may be used as a therapeutic agent for preterm birth. An increase in the muscle-collagen ratio in the proximal cervix may easily cause the cervical dilatation during pregnancy and cause preterm birth. Thus, the increase in the muscle-collagen ratio in the cervix may be inhibited by preventing the fibroblasts from differentiating into the myofibroblasts in the cervix, thereby reducing the possibility of preterm birth. 
     In an embodiment, the agent may comprise at least one of a transforming growth factor beta1 (TGF-β1) inhibitor and plasma fibronectin. 
     The present inventors confirmed the effect obtained by administering various candidates known to be used for a wound treatment, and, as a result, confirmed that the TGF-β1 inhibitor or plasma fibronectin may inhibit an increase in the muscle/collagen ratio in the proximal cervix, which is a causal index of preterm birth. 
     In an embodiment, the TGF-β1 inhibitor may be a compound represented by the following Formula 1: 
     
       
         
         
             
             
         
       
     
     The compound represented by Formula 1, also known as SB-431542, has an IUPAC name of 4-(5-benzol[1,3]dioxol-5-yl-4-pyrldin-2-yl-1H-imidazol-2-yl)-benzamide, and a Cas number is 301836-41-9. The SB-431542 is known to inhibit ALK4, ALK5 and ALK7, and an activin/BMP/TGF-β pathway. 
     The present inventors confirmed that an expression level of α-SMA is decreased by primarily culturing the fibroblasts from the cervix of an animal model of preterm birth, and treating the SB-431542 in step p 2 . 
     The plasma fibronectin may be a polypeptide consisting of the amino acid sequence of SEQ ID NO: 1. Fibronectin is known to play an important role in restoring a tissue as ECM glycoprotein and is classified into plasma fibronectin and cellular fibronectin. Plasma fibronectin and cellular fibronectin have different sequences from each other and may have different effects in preventing preterm birth. Cellular fibronectin is known to promote differentiation into myofibroblasts, but the present inventors confirmed that plasma fibronectin can inhibit the differentiation into myofibroblasts. The origin of the plasma fibronectin is not particularly limited, and for example, a product which is extracted from the bovine plasma and then sterilized may be used, or a commercially available product may be purchased and used. 
     In an embodiment, the composition may be administrated before pregnancy. The pharmaceutical composition may be administered during pregnancy, but may be administered before pregnancy to prevent preterm birth by inhibiting in advance an increase in the muscle-collagen ratio in the proximal cervix, which is the cause of preterm birth. 
     In an embodiment, the composition may be for the administration immediately after injury of the cervix. The injury of the cervix includes not only damage caused by surgery such as induced abortion, but also damage that may occur during daily life such as sex, vaginitis, pelvic infection, and damage caused by viral infection. The muscle-collagen ratio in the proximal cervix may be increased even during daily life, and for example, can also be increased by minor damage or inflammation of the cervix that does not require special treatment. Therefore, if the pharmaceutical composition of the present disclosure is administered before pregnancy or immediately after the injury of the cervix, it is possible to effectively prevent preterm birth by blocking an increase in the muscle ratio of the cervix in advance. The term “immediately” may be before recovery after cervical injury, and specifically within 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 12 hours, 1 It may be within days, within 2 days, within 3 days, within 4 days, within 5 days, within 6 days, or within 7 days. 
     In one embodiment, the composition may be administered simultaneously or sequentially with an antibiotic or antiviral agent prescribed in case of cervical injury. 
     The pharmaceutical composition may be formulated and used in the form of, but is not limited to, oral formulation such as powders, granules, capsules, tablets and aqueous suspensions, external preparations, suppositories, patches, and sterile injectable solutions, according to a conventional method. The pharmaceutical composition may comprise a pharmaceutically acceptable carrier. For oral administration, as the pharmaceutical acceptable carrier, binders, lubricants, disintegrants, excipients, solubilizers, dispersants, stabilizers, suspending agents, coloring agents, flavoring agents, etc. may be used. For an injection, as the pharmaceutical acceptable carrier, buffering agents, preservatives, painlessness agents, solubilizers, isotonic agents, stabilizers, etc. may be mixed and used. For topical administration, as the pharmaceutical acceptable carrier, base agents, excipients, lubricants, preservatives, etc. may be used. The formulation of the pharmaceutical composition may be variously prepared by mixing with a pharmaceutically acceptable carrier as described above. For example, for oral administration, the pharmaceutical composition may be prepared in the form of tablets, troches, capsules, elixirs, suspensions, syrups, wafers, etc., and for an injection, the pharmaceutical composition may be prepared in unit dosage ampoules or multiple dosage forms. Also, the pharmaceutical composition may be formulated as solutions, suspensions, tablets, capsules, sustained-release preparations, etc. 
     Examples of carriers, excipients and diluents suitable for formulation may include lactose, dextrose, sucrose, sorbitol, mannitol, xylitol, erythritol, malditol, starch, gum acacia, alginate, gelatin, calcium phosphate, calcium silicate, cellulose, methyl cellulose, microcrystalline cellulose, polyvinylpyrrolidone, water, methylhydroxybenzoate, propylhydroxybenzoate, talc, magnesium stearate or mineral oil, etc. In addition, fillers, anti-aggregating agents, lubricants, wetting agents, flavoring agents, emulsifiers, preservatives, etc. may additionally be included. 
     In an embodiment, the composition may be administered orally, intravenously, intramuscularly, intraarterially, intramedullary, intrathecally, intracardially, transdermally, subcutaneously, intraperitoneally, intranasally, intestinally, topically, sublingually, intracervically, intravaginally, intrauterally, or intrarectally. 
     In an embodiment, the composition may be administered through a systemic administration route. The systemic administration is a route of administration in which the drug affects the system through the circulatory organs, and may be, for example, oral or injection administration. The systemic administration is distinct from the local administration. According to an embodiment, the composition of the present disclosure exhibited superior effects when administered orally or intraperitoneally, which is systemic administration, than intravaginal administration, which is topical administration. 
     In an embodiment, the composition may be administered through an administration route, other than intravaginal administration. 
     According to an embodiment, the composition may be administered orally or by injection, and the injection may be administered intraperitoneally. According to an embodiment, it was confirmed that there is a difference in effect depending on the administration route, and the oral administration or intraperitoneal administration exhibits the effect of lowering the muscle/collagen ratio, which is superior to that of intravaginal administration. 
     In the present disclosure, “parenteral” includes subcutaneous, intradermal, intravenous, intramuscular, intraarticular, intrasynovial, intrasternal, intrathecal, intralesional, intravaginal, intrauterine, and intracranial injection or infusion techniques. The pharmaceutical composition of the present disclosure may also be administered in the form of suppositories for rectal administration. 
     Dosage forms for topical or transdermal administration of the compound of the present disclosure may include ointments, pastes, creams, lotions, gels, powders, solutions, sprays, inhalants or patches. The active ingredient may be mixed with a pharmaceutically acceptable carrier and any necessary preservatives or buffers under sterile conditions. Ophthalmic formulations, for example, ear drops and eye drops may be included within the scope of the present disclosure. Additionally, the compound of the present disclosure may be used in the form of transdermal patches. Patches can be made by dissolving or dispersing the compound in an appropriate medium. Absorption enhancers may be used to increase the flow of the compound through the skin. The rate of absorption may be controlled by dispersing the compound in a rate controlling film or a polymer matrix or gel. 
     The pharmaceutical composition may be variously applied, depending on a variety of factors, including the activity of the specific compound used, age, weight, general health, sex, formula, administration time, administration route, excretion rate, drug combination and the severity of specific disease to be prevented or treated. The dosage of the pharmaceutical composition varies depending on the patient&#39;s condition and weight, degree of disease, drug form, administration route and administration duration, but may be appropriately selected by those skilled in the art, and may be administered at 0.0001 to 50 mg/kg or 0.001 to 50 mg/kg daily. Administration may be performed once a day, or may be divided several times a day. The above dosage does not in any way limit the scope of the present disclosure. The pharmaceutical composition according to the present disclosure may be formulated as pill, dragee, capsule, liquid, gel, syrup, slurry, or suspension. The pharmaceutical composition may be prescribed simultaneously or sequentially with a therapeutic agent, an antiviral agent, or an antibiotic, to a patient with cervix-related damage, for example, inflammation such as vaginitis, viral infection, or physical injury, and an increased risk of preterm birth may be prevented by inhibiting the increase in the muscle/collagen ratio in the cervix, which is caused by the injury. 
     Another aspect of the present disclosure provides a method of preventing or treating preterm birth in a subject in need thereof, the method comprising administering an effective amount of an agent that inhibits the differentiation of fibroblasts to myofibroblasts in cervix. 
     In an embodiment, the agent may comprises at least one of a transforming growth factor beta1 (TGF-β1) inhibitor and plasma fibronectin. 
     In an embodiment, the TGF-β1 inhibitor may be a compound represented by the following Formula 1: 
     
       
         
         
             
             
         
       
     
     In an embodiment, the plasma fibronectin may be a polypeptide consisting of the amino acid sequence of SEQ ID NO: 1. 
     In an embodiment, the composition may be administered prior to pregnancy. 
     In an embodiment, the composition is administered immediately after cervical injury. 
     Another aspect of the present disclosure provides a method of screening an agent for prevention or treatment of preterm birth, the method comprising steps of: contacting fibroblasts isolated from the cervix with a TGF-β1 and a test substance; measuring an expression level of α-SMA in the fibroblasts; and determining the test substance as candidates for the prevention or treatment of preterm birth if the test substance inhibits the expression of α-SMA. 
     The cervix may be of a mammal, human, or non-human animal, and the specific examples of the non-human animal may include a non-human primate, rodent, pig, mouse, rat, dog, cat, cow, goat, or an animal model of preterm birth. 
     The fibroblasts may be cells obtained by primarily culturing a tissue obtained from the cervix, or by secondarily culturing cells by separating and seeding fibroblasts from primary cultured cells. 
     The contact of test substance may be performed 12 to 36 hours, 18 to 30 hours, 22 to 26 hours, or 24 hours after the secondary culture. 
     The α-SMA (alpha smooth muscle actin) is a marker of myofibroblasts, and whether the test substance may inhibit the differentiation of fibroblasts into myofibroblasts may be confirmed by measuring the expression level of α-SMA. 
     The expression level of α-SMA may be measured at the level of the transcription product by using a method known in the art. For example, mRNA of α-SMA may be quantified by measurement using a probe with a hybridization method or an amplification-based detection method. Alternatively, the expression level of α-SMA may be measured at the level of a protein that is a translation product. The method of measuring the protein may include immunoassay methods known in the art, such as immunoprecipitation using an antibody that specifically recognizes the α-SMA protein, Western blot, immunohistochemical analysis, etc. The antibody may be a monoclonal or polyclonal antibody, and any fragment or modification of the antibody retaining the ability to bind to a target protein may be used. 
     In an embodiment, the cervix may be a proximal cervix. The cervix may be divided into proximal, middle, and distal cervix, and the muscle/collagen ratio in the proximal cervix is most closely related to the risk of preterm birth. Therefore, the inhibitory effect of the candidate substance on preterm birth may be more accurately confirmed, by measuring the degree of muscle fiber differentiation of fibroblasts obtained from the proximal cervix. 
     The use of the pharmaceutical composition for preventing or treating preterm birth according to an embodiment may effectively prevent preterm birth by inhibiting an increase in the muscle-collagen ratio in the cervix that causes preterm birth, by administering the composition before or during pregnancy. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  shows a process of producing an animal model of preterm birth according to an embodiment. 
         FIG. 2  shows a result of confirming a change in collagen content through Masson&#39;s Trichrome histochemical staining for each location in cervix of the animal model of preterm birth according to an embodiment. 
         FIG. 3  shows a result of measuring the expression level of the smooth muscle marker, α-SMA (alpha-smooth muscle actin) according to an embodiment. 
         FIG. 4  shows a result of confirming a change in the muscle-collagen ratio in the animal model of preterm birth according to an embodiment. 
         FIG. 5  shows an experimental process of treating fibroblasts isolated from cervical cells of a mouse, with TGF-β1 and SB-431542, which is a TGF-β1 inhibitor, according to an embodiment. 
         FIG. 6  shows a result of confirming the protein expression level of α-SMA by Western blotting after the experiment of  FIG. 5 . 
         FIG. 7  show a result of confirming the mRNA expression level and the protein expression level of α-SMA after treating fibroblasts, isolated from cervical cells of a mouse, with TGF-β1 and SB-431542, which is a TGF-β1 inhibitor, according to an embodiment. 
         FIG. 8  shows a result of immunofluorescence staining for α-SMA protein after treating fibroblasts isolated from cervical cells of a mouse, with TGF-β1 and SB-431542, which is a TGF-β1 inhibitor, according to an embodiment. 
         FIG. 9  shows a result of observing a change in expression of collagen 1 after treating fibroblasts isolated from cervical cells of a mouse, with TGF-β1 and SB-431542, which is a TGF-β1 inhibitor, according to an embodiment. 
         FIG. 10  shows a result of observing a change in the expression level of α-SMA, the expression level of type 1 collagen, and the α-SMA/collagen ratio after treating fibroblasts isolated from cervical cells of a mouse, with TGF-β1 and plasma fibronectin, respectively, according to an embodiment. 
         FIG. 11  shows a result of confirming a change in the expression level of α-SMA after treating fibroblasts isolated from cervical cells of a mouse, with a TGF-β1, chondroitin sulfate (CS), tenascin-C (TN-C), and TGF-β3, respectively, according to an embodiment. 
         FIG. 12  shows a proximal site and distal site in cervical tissues obtained after intravaginal, oral, and intraperitoneal administration of SB-431542 or fibronectin. 
         FIG. 13  is a result showing α-SMA (A), type I collagen (B), and their ratio (M/C ratio) (C) after the intravaginal administration of fibronectin. 
         FIG. 14  is a result showing α-SMA (A), type I collagen (B), and their ratio (M/C ratio) (C) after intravaginal administration of SB-431542. 
         FIG. 15  is a result showing α-SMA (A), type I collagen (B), and their ratio (M/C ratio) (C) after intraperitoneal or oral administration of SB-431542. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, one or more embodiments will be described in more detail through examples. However, these examples are only for illustrative purposes and the scope of the present disclosure is not limited to these examples. 
     Example 1: Production of Animal Model of Preterm Birth 
     The process of producing an animal model of preterm birth will be described with reference to  FIG. 1 . Sexually mature female C57BL/6 mice were used in the experiment. The laboratory was maintained at a constant temperature (22 to 24° C.) with a 12-hour day/night cycle. 
     Mice were randomly assigned to one of four groups, and one group was composed of ten mice. The four groups were divided into A (control, sham), B (cervical partial excision), C (LPS injection), and D (cervical partial excision and LPS injection). 
     Partial cervical tissue excision was performed at each 5-week old. Specifically, each mouse was anesthetized by inhalation of 2 to 4% isoflurane, and then the cervix thereof was grasped by using forceps, and an excision was made to a depth of 1 mm using a scalpel. In order to minimize bleeding after excision, each mouse was compressed to stop bleeding. The length of the cervix was 2.5 mm, about 40% of the cervix was excised, and an average weight of the excised tissues of cervix was 7 mg. Mating was induced 3 weeks after cervical tissue excision to induce pregnancy, and the probability of pregnancy was about 50%. The day when the mucus plug was in the vagina was set to the first day of pregnancy. 
     Preterm birth was induced by injecting 100 ug of lipopolysaccharide (LPS, lipopolysaccharide from  Escherichia coli  055:B5, Sigma-Aldrich)/100 uL of NS between the first and second fetal sacs of right uterus on the 16th day of pregnancy. Twelve hours after delivery, the mice were sacrificed and the uterus was removed. 
     The mean gestational period was significantly lower in group D, on which both the cervical excision and LPS injection are performed than group A of the control. When delivery was defined as preterm birth within 24 hours after the LPS injection or day 18 before the LPS injection, the proportion of preterm birth was 0% in group A, 30% in group B, 60% in group C, and 100% in group D. 
     Example 2: Confirmation of Increase in Muscle-Collagen Ratio in Cervix 
     A sample of cervix was obtained by cutting a portion just above the intersection of the cervix. The tissue of cervix was treated overnight with 4% neutral buffered formalin, fixed, processed, and placed in a paraffin block. Tissue sections (4 μm) were cut from the blocks, mounted on slides, deparaffinized with xylene, and rehydrated with ethanol. Each section was stained with hematoxylin and eosin and the length of the cervix was measured. 
     To confirm the muscle (smooth muscle)-collagen ratio, histochemical staining was performed using a Masson&#39;s trichrome staining kit (NovaUltra). An average percentage of collagen and smooth muscle was analyzed by using Image J software (NIH, Bethesda, Md.) for images at 200 magnification for the proximal cervix, middle cervix, and distal cervix regions per section. 
       FIG. 2  shows a visualization of collagen made by Masson&#39;s trichrome staining, which shows that the specific gravity of collagen was reduced in the proximal cervix and the middle cervix of the animal model of preterm birth. 
     The experimental method to confirm the expression of α-SMA is as follows. The tissue was put in 4% paraformaldehyde for one day and fixed. In order to prevent non-specific binding, the tissue was immersed in a blocking buffer and reacted at room temperature for 5 hours. The primary antibody was mixed and treated with 5% bovine serum albumin (BSA, Sigma, USA) blocking buffer, and then reacted at room temperature. After the completion of a primary antibody reaction, it was washed with 1×PBS, and a secondary antibody (Alexa 488 dye) was mixed and treated with 5% BSA blocking buffer. After the treatment with the secondary antibody, it was washed 3 times with 1×PBS. Since the secondary antibody is sensitive to light, the treatment with the secondary antibody was performed in the dark during the reaction time. All tissue samples were observed through a fluorescence microscope. 
       FIG. 3  shows a result of confirming the expression of α-SMA, one of the markers of smooth muscle cells, which shows a significant increase in the expression of α-SMA when cervical excision and LPS infection occurred. 
       FIG. 4  shows a result of confirming that the proximal cervix has a higher muscle ratio than the middle cervix and the distal cervix. 
     According to Table 1 below, it was confirmed that the muscle-collagen ratio in the proximal cervix further increased by up to 65% in group D, on which both an excision of cervical tissue and induction of the inflammatory response by LPS were performed, than those of the other groups. 
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                   
                   
                 D  
                   
               
               
                   
                   
                 B  
                   
                 Cervical  
                   
               
               
                   
                   
                 Cervical  
                   
                 tissue  
                   
               
               
                   
                 A  
                 tissue  
                 C  
                 excision +  
                 p-  
               
               
                   
                 Sham  
                 excision  
                 LPS  
                 LPS  
                 Value 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 Proximal  
                 0.9 ± 0.5  
                 0.8 ± 0.6  
                 0.6 ± 0.3  
                 1.3 ± 0.6  
                 0.037 a    
               
               
                 cervix  
                   
                   
                   
                   
                   
               
               
                 Middle  
                 0.9 ± 0.7  
                 0.7 ± 0.4  
                 0.5 ± 0.2  
                   1 ± 0.7  
                 0.229  
               
               
                 cervix  
                   
                   
                   
                   
                   
               
               
                 Distal  
                 0.8 ± 0.5  
                 0.7 ± 0.4  
                 0.4 ± 0.2  
                 1.1 ± 0.6  
                 0.269  
               
               
                 cervix 
               
               
                   
               
            
           
         
       
     
     It was found that an increase in the ratio of the proximal muscles of the cervix may cause the cervix dilatation during pregnancy, leading to preterm birth. 
     Example 3: Confirmation of Effects of Reducing Muscle/Collagen Ratio in Cervix Upon Administration of SB431542 
     The experiment process will be described with reference to  FIG. 5 . Cells were isolated from the cervixes of 4- to 6-week old C57BL/6 mice and subjected to primary cell culture in 60 mm dishes (step p 0 ). After step p 01  is performed by culturing for 12 to 15 days, the number of fibroblasts was measured, and fibroblasts were seeded in a well dish at a density of about 0.3×10 6  cells/dish, followed by secondary culture (step p 2 ). After 1 day from the secondary culture, it was treated for 2 hours in a serum-free medium, and then treated with 10 ng/ml of TGF-β1 per dish to induce differentiation into myofibroblasts, and experimental group was treated with SB-431542, which is a TGF-β1 inhibitor, at each concentration of 0, 2, 8 and 16 μM. Two days after drug treatment, cells were washed with 10× phosphate buffered saline (PBS; Affymetrix), and proteins were extracted with RIPA buffer. Western blot was performed to investigate the expression levels of α-SMA, a marker of myofibroblasts, and  COLI , a marker of collagen. As the primary antibodies, α-smooth muscle actin (1:1000) and type I collagen (1:500) antibody were reacted at 4° C. overnight, and as the secondary antibody, anti-mouse IgG (CellNest, USA) was added thereto and was detected after the reaction for 1 hour at room temperature. 
     Referring to  FIGS. 6A and 6B , it could be confirmed that when 8 μM of SB-431542 per dish was treated, the expression of α-SMA protein was reduced, thereby inhibiting differentiation into myofibroblasts. In the subsequent experiment, the experiment was conducted by treating SB-431542 at a concentration of 8 μM/dish based on the dish seeded with 0.3×10 6  cells. 
       FIG. 7  shows the results of measuring the mRNA expression level and protein expression level of α-SMA after treating fibroblasts with SB-431542. It was confirmed that according to  FIG. 7A , there was no significant change in the mRNA expression level of α-SMA, but according to  FIG. 7B , the protein expression level of α-SMA was significantly reduced. Therefore, it could be seen that the treatment with SB-431542 could induce a decrease in the muscle/collagen ratio in the proximal cervix by inhibiting the expression of α-SMA protein. 
       FIG. 8  shows a result of confirming the degree of differentiation into myofibroblasts by measuring the protein expression level of α-SMA by immunofluorescence method. It was confirmed from the result above that if it was treated simultaneously with TGF-β1 and SB-431542, differentiation from fibroblasts to myofibroblasts was inhibited by SB-431542, as the fluorescence detection of α-SMA was reduced. 
       FIG. 9  shows a result of confirming that TGF-β1 and SB-431542, which is a TGF-β1 inhibitor, have no effect on collagen 1 expression. 
     Taken together with the above experimental results, SB-431542, which is a TGF-β1 inhibitor, inhibits muscle differentiation when administered to the cervix, and does not affect collagen expression. Therefore, SB-431542 may be expected to prevent preterm birth by inhibiting the increase in the muscle-collagen ratio in the proximal cervix, which can occur during cervical injury. 
     Example 4: Comparison of Effects of Plasma Fibronectin on Decrease in Muscle/Collagen Ratio in Cervix 
     Plasma fibronectin (FN) was administered as a candidate drug capable of inhibiting an increase in the muscle-collagen ratio in the proximal cervix, and changes in the expression levels of α-SMA and type 1 collagen were analyzed. The experiment was performed in the same manner as in Example 3 and  FIG. 5 , except for the administered drug. For plasma fibronectin, the fibronectin bovine plasma product purchased from Sigma-Aldrich was used, and the dosage thereof was 2 μg/cm 2  per well. 
     It could be confirmed from  FIG. 10A  that the expression level of α-SMA, which is a differentiation index of muscle cells, was increased by the administration of TGF-β1, but when plasma fibronectin was administered together, the expression level thereof was decreased as much as in the control group wherein TGF-β1 was not administered. In addition, it was confirmed from  FIG. 10B  that collagen expression was also slightly decreased in the group treated with TGF-β1 and plasma fibronectin together. However, it could be seen from  FIG. 10C , which is a result of measuring the ratio of α-SMA and collagen 1 that plasma fibronectin reduced the ratio of α-SMA/collagen 1, which is increased by TGF-β1, and inhibited the increase in the muscle-collagen ratio in the proximal cervix, which may occur during cervical injury, thereby preventing preterm birth. 
     Example 5: Comparison of Effects of Other Wound Healing Drugs on Decrease in Muscle/Collagen Ratio in Cervix 
     Chondroitin sulfate (CS), tenascin C (TN-C), or TGF-β3, which are drugs used for a wound treatment, were administered, and the inhibitory effect on the increase in the muscle-collagen ratio was confirmed. The experiment was performed in the same manner as in Example 3 and  FIG. 5 , except for the administered drug. 
     Chondroitin sulfate was purchased from Sigma-Aldrich, and 50 μg/ml was treated. Tenascin-C was purchased from EMD-Millipore, and 2 μg/ml was treated. TGF-β3 was purchased from Sigma-Aldrich and 10 μg/ml was treated. 
     According to  FIG. 11 , chondroitin sulfate (CS,  FIG. 11A ), tenascin-C (TN-C,  FIG. 11B ), and TGF-β3 ( FIG. 11C ) slightly inhibited the increase in α-SMA expression by TGF-β1, but there was a significant difference from the inhibitory effect of α-SMA expression by SB-431542 (see  FIG. 7 ). Therefore, it was difficult to expect that CS, TN-C, and TGF-β3 would exhibit the effect of inhibiting the expression of α-SMA and the effect of inhibiting the increase in the muscle-collagen ratio in the proximal cervix. 
     Therefore, it was confirmed that the use of SB-431542 and plasma fibronectin among the existing drugs used for wound healing can have an effect of preventing preterm birth by inhibiting the differentiation of fibroblasts into myofibroblasts in the cervix. 
     Example 6: Differences in Effects Depending on Drug Administration Route 
     6-1. A Method for Intravaginal Administration, Oral Administration (PO), and Intraperitoneal Administration (IP) of Drugs 
     Sexually mature female C57BL/6 mice were used for experiments in vivo. The laboratory was maintained at a constant temperature (22 to 24° C.) with a 12-hour day/night cycle. Partial cervical tissue excision was performed at each 5-week old. Specifically, each mouse was anesthetized by inhalation of 2 to 4% isoflurane, and then the cervix thereof was grasped by using forceps, and an excision was made to a depth of 1 mm using a scalpel. In order to minimize bleeding after excision, each mouse was compressed to stop bleeding. The length of the cervix was 2.5 mm, about 40% of the cervix was excised, and the average weight of the excised tissues was 7 mg. 
     At the same time as the cervical tissue excision, liquid fibronectin, and SB-431542 dissolved in DMSO were injected into the cervix through the vagina using a feeding needle. 
     Liquid fibronectin (plasma) was infused into the cervix through the vagina daily for 3 weeks at each dose of 20 mg and 0.2 mg (20 mg, diluted 10 times, expressed as FN (X10)). SB-431542 was dissolved in 5% DMSO, and infused into the cervix through the vagina daily for 3 weeks at each dosage of 20 mg and 0.2 mg (20 mg, diluted 10 times, indicated as SB-431542 (X10). After the drug treatment for 3 weeks, samples were obtained from the proximal cervix and distal cervix regions divided in the cervical tissue (see  FIG. 13 ). 
     The protein extraction method for confirming the expression of α-SMA and type I collagen (Collagen I) was as follows. After an RIPA buffer (RIPA lysis buffer, 150 mM NaCl, 1% Triton X-100, 1% SD, 0.1% SDS, 50 mM Tris-13 HCl, 2 mM EDTA) and protease inhibitor cocktail (GenDEPOT, P3100-005) were mixed, 100 ul of the mixture was added to separate cervical tissue in each region and pulverized using a homogenizer. After the pulverized product was left on ice for 40 minutes, centrifugation was performed for 15 minutes using a centrifuge (13,000 rpm, 4 degrees). Only the supernatant was used after storage in a new tube. Protein quantification was carried out by a Bradford method (Protein assay dye reagent concentrate buffer, BioRad). 
     Western blot method for confirming the expression of α-SMA and type I collagen was as follows. The extracted protein was loaded on a 10% SDS PAGE gel at 5 ug each and transferred to a nitrocellulose membrane. After blocking with 5% skim milk, α-smooth muscle actin antibody (1:1000, NSJ Bioreagents, V2001) as the primary antibodies, and type I collagen antibody (1:500, Abcam, ab88147), GAPDH (1:1000, Santa Cruz, sc376559) were reacted at 4° C. overnight, and anti-mouse IgG (CellNest, USA) as a secondary antibody was added thereto and reacted for 1 hour at room temperature, and then was developed and detected by using an ECL kit (SuperSignal West Pico PLUS Chemiluminescent Substrate, Thermo Scientific). 
     For oral administration (PO), the drug was administered to the esophagus through the mouth using a feeding needle at the same time as the cervical tissue excision. SB-431542 was dissolved in 5% DMSO and injected in an amount of 10 mg/kg with each 100 ul for 3 weeks. 
     For intraperitoneal infusion (IP), the drug was administered intraperitoneally using an insulin syringe at the same time as the cervical tissue excision. SB-431542 was dissolved in 5% DMSO and infused in an amount of 10 mg/kg with each 100 ul for 3 weeks. 
     For the dosage of SB-431542, reference was made to the paper of Dario in the Nature Medicine “Nilotinib reduces muscle fibrosis in chronic muscle injury by promoting TNF-mediated apoptosis of fibro/adipogenic progenitors.” 
     6-2. Experimental Results 
       FIG. 14  shows the results after infusing liquid fibronectin into the cervix through the vagina daily for 3 weeks at each dose of 20 mg and 0.2 mg (20 mg, diluted 10 times, expressed as FN (X10)). A is α-SMA, B is type I collagen, and C is an M/C ratio. In  FIG. 14C , when it was treated with 20 mg and 0.2 mg of fibronectin, the M/C ratio was decreased compared to the cervical excision group. This is a significant level compared to the control group on which cervical excision was not performed. 
       FIG. 15  shows the results after infusing SB-431542 into the cervix through the vagina daily for 3 weeks at each dose of 20 mg and 0.2 mg (20 mg diluted 10 times, expressed as SB-431542 (X10)). A is α-SMA, B is type I collagen, and C is an M/C ratio. In  FIG. 15C , the cervical excision group had an M/C ratio higher than that of the control group, but there was no significant change in the group treated with 20 mg and 0.2 mg of SB-431542. 
       FIG. 16  shows the results after drug infusion through oral administration or intraperitoneal infusion of SB-431542 at a dose of 10 mg/kg daily for 3 weeks. A is α-SMA, B is type I collagen, and C is an M/C ratio. In  FIG. 16C , the cervical excision group showed an M/C ratio higher than that of the control group, and the group to which DMSO was infused through oral administration showed an M/C ratio similar to that of the control group, whereas the group to which SB-431542 was administered through oral administration or intraperitoneal injection showed an M/C ratio lower than that of the cervical excision group.