Patent Publication Number: US-2022211772-A1

Title: USES OF INTESTINAL BACTERIA IN PREPARATION OF A MEDICAMENT FOR PROMOTING A PROLIFERATION OF TCR yo+T CELLS

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to PCT Application No. PCT/CN2019/086598, having a filing date of May 13, 2019, which claims priority to Chinese Application No. 201910375519.0, having a filing date of May 7, 2019, the entire contents both of which are incorporated herein by reference. 
    
    
     FIELD OF TECHNOLOGY 
     The following relates to the technical field of immunology, particularly, it relates to at least one of a use of intestinal bacteria in preparation of a medicament for promoting a proliferation of TCR γδ +  T cells, a use of intestinal bacteria in preparation of a medicament for promoting an accumulation of CD8 positive cytotoxic T lymphocytes, or a use of intestinal bacteria in preparation of a medicament for preventing and/or treating cancers, and at least one of a composition for promoting a proliferation of TCR γδ +  T cells, a composition for promoting an accumulation of CD8 positive cytotoxic T lymphocytes, or a composition for preventing and/or treating cancers. 
     BACKGROUND 
     Cancer has become a serious problem threating human health and livelihood. The latest global statistics from the World Health Organization (WHO) show that cancer is among the leading cause of death worldwide. In 2018, there were 1.81 million new cases and about 0.96 million cancer-related deaths around the world. The morbidity and mortality of cancer have increased rapidly. And in 2018, liver cancer had been the fifth leading cause of death globally, and there were 0.627 million liver cancer deaths, accounting for 8.2% of all cancer deaths. Traditional treatment methods comprise surgical treatment, chemotherapy, radiotherapy, traditional Chinese medicine (TCM) therapy and the like, which are widely used in clinical and have reliable curative effects. However, these treatment methods have impacts on the quality of life for patients to different degrees. Particularly, most tumors, like liver cancer, are found at an advanced stage and are not suitable for the radical surgical-treatment. Therefore, it is urgent to develop safer and more effective treatment methods. 
     Since tumor immunotherapy is listed as the most significant breakthrough in annual scientific research by  Science  in 2013, a biological immunotherapy for tumors has developed rapidly. The tumor immunotherapy mainly refers to achieve anti-tumor effects by increasing the activity of  immune system in body and relieving immunosuppression. However, most of patients have poor efficacy, because CD8 positive cytotoxic T lymphocytes in tumor microenvironment are so insufficient that they are unable to provide effective immune response. Therefore, it is urgent to find an immunotherapy approach to effectively modulate the immune system. T cells can be classified into αβ T cells and γδ T cells according to receptors on the surface of the T cells. The receptors on the surface of γδ T cells consist of two glycoprotein chains, γ chain and δ chain. The γδ T cells can directly identify proteins, peptides, or non-peptide antigens without antigen presentation by histocompatibility complex molecule on the surface of cell, which is an important biological feature. The γδ T cells are mainly located on skins and mucosal tissues, such as alimentary tract, respiratory tract, reproductive system, etc. At present, it is found in some studies that the γδ T cells can indirectly promote anti-tumor immune response for many malignant cancers by cytotoxicity or by stimulating and regulating the biological functions of other immune cells, for example dendritic cells, or CD8 positive T cells. However, it has not been found whether ten types of intestinal bacteria, such as  Alistipes shahii  and the like can promote an effective accumulation and an effective proliferation of CD8 positive cytotoxic T lymphocytes and/or γδ T cells (TCR γδ +  T cells). 
     The human intestinal bacteria have significant regulatory effects on the body and play an important role in the occurrence and development of the diseases. There are millions of bacteria living in human gut where anaerobic bacteria dominate. The present research indicates that intestinal bacteria play a powerful role in exhibiting anti-tumor effects by stimulating the activity of immune system in body and eliminating immunosuppression for tumor cells.  Alistipes shahii  is a Gram-negative, obligate anaerobe with rod shape.  Eubacteria  is a Gram-negative, motile, non-spore-forming, obligate anaerobe, which ferments glucose or peptone to produce substances mainly including a large amount of butyric acid, acetic acid, or formic acid.  Eubacteria  is found in animal cavity, faeces, animal and plant products, and soils.  Ruminococcus  is one type of  Clostridium. Anaerofustis  is a Gran-positive, non-spore obligate anaerobe with rod shape.  Prevotella copri  is a Gram-negative anaerobe and a symbiotic human gut bacterium, which is found to be relevant to the susceptibility of rheumatoid arthritis and the insulin resistance of the diabetic. 
     SUMMARY 
     An aspect relates to a technical solution for effectively promoting a proliferation of TCR γδ +  T cells and an accumulation of CD8 positive cytotoxic T lymphocytes in prevention and/or treatment of tumors.  
     An aspect relates to a use of any one or more of intestinal bacteria selected from a group consisting of  Alistipes shahii, Eubacterium ramulus, Eubacterium siraeum, Prevotella ruminicola, Ruminococcu lactaris, Anaerofustis stercorihominis, Clostridium nexile, Sanguibacteroides justesenii , Dorea formicigenerans , and  Bifidobacterium saeculare  in preparation of a medicament for promoting a proliferation of TCR γδ +  T cells (γδ cells for short). 
     In an embodiment, the intestinal bacteria are any one or more of live intestinal bacteria; genetically recombined, altered or modified, attenuated, chemically treated, physically treated, or inactivated intestinal bacteria; lysate of intestinal bacteria; and/or culture supernatant of intestinal bacteria. 
     In an embodiment, an increase in the proliferation of TCR γδ +  T cells is characterized by an increase in a relative amount of TCR γδ +  T cells in cecum cells. 
     Accordingly, another aspect relates to a composition for promoting a proliferation of TCR γδ +  T cells, comprising any one or more of intestinal bacteria selected from a group consisting of  Alistipes shahii, Eubacterium ramulus, Eubacterium siraeum, Prevotella ruminicola, Ruminococcu lactaris, Anaerofustis stercorihominis, Clostridium nexile, Sanguibacteroides justesenii, Dorea formicigenerans , and  Bifidobacterium saeculare  as an active ingredient. 
     In an embodiment, the intestinal bacteria are any one or more of live intestinal bacteria; genetically recombined, altered or modified, attenuated, chemically treated, physically treated, or inactivated intestinal bacteria; lysate of intestinal bacteria; and/or culture supernatant of intestinal bacteria. 
     Another aspect relates to a use of any one or more of intestinal bacteria selected from a group consisting of  Alistipes shahii, Eubacterium ramulus, Eubacterium siraeum, Prevotella ruminicola, Ruminococcu lactaris, Anaerofustis stercorihominis, Clostridium nexile, Sanguibacteroides justesenii, Dorea formicigenerans , and  Bifidobacterium saeculare  in preparation of a medicament for accumulating CD8 positive cytotoxic T lymphocytes. 
     In an embodiment, the intestinal bacteria are any one or more of live intestinal bacteria; genetically recombined, altered or modified, attenuated, chemically treated, physically treated, or inactivated intestinal bacteria; lysate of intestinal bacteria; and/or culture supernatant of intestinal bacteria. 
     In an embodiment, the accumulation of CD8 positive cytotoxic T lymphocytes is characterized by an increase in a relative amount of CD8 positive cytotoxic T lymphocytes in tumor microenvironment.  
     Accordingly, another aspect relates to a composition for promoting an accumulation of CD8 positive cytotoxic T lymphocytes, comprising any one or more of intestinal bacteria selected from a group consisting of  Alistipes shahii, Eubacterium ramulus, Eubacterium siraeum, Prevotella ruminicola, Ruminococcu lactaris, Anaerofustis stercorihominis, Clostridium nexile, Sanguibacteroides justesenii, Dorea formicigenerans , and  Bifidobacterium saeculare  as an active ingredient. 
     In an embodiment, the intestinal bacteria are any one or more of live intestinal bacteria; genetically recombined, altered or modified, attenuated, chemically treated, physically treated, or inactivated intestinal bacteria; lysate of intestinal bacteria; and/or culture supernatant of intestinal bacteria. 
     The inventors of the present disclosure found that it is possible for ten types of intestinal bacteria such as  Alistipes shahii  to promote an accumulation of CD8 positive cytotoxic T lymphocytes and/or a proliferation of TCR γδ +  T cells in tumor so as to modulate T cell immune response. Specifically, the inventors found that, when any one or more of ten types of intestinal bacteria, or physiological active ingredients or compositions obtained from these bacteria are comprised in tumors, they can promote the proliferation of TCR γδ +  T cells and/or the accumulation of CD8 positive cytotoxic T lymphocytes in tumor microenvironment in cecum. Thus, anti-tumor effects of T cells are improved to achieve objectives of the present disclosure. Specifically, they are achieved by strengthening the functions of anti-tumor immune cell subsets. 
     Specifically, the CD8 positive cytotoxic T lymphocytes refer to CD8 T cells characterized by the phenotype of CD 8   + , and TCR γδ +  T cells (γδ TCR + for short) refer to γδ T cells characterized by the phenotype of TCR y 6   + . 
     Further, another aspect relates to a use of any one or more of intestinal bacteria selected from a group consisting of  Alistipes shahii, Eubacterium ramulus, Eubacterium siraeum, Prevotella ruminicola, Ruminococcu lactaris, Anaerofustis stercorihominis, Clostridium nexile, Sanguibacteroides justesenii, Dorea formicigenerans , and  Bifidobacterium saeculare  in preparation of a medicament for preventing and/or treating tumors. 
     In an embodiment, the intestinal bacteria are any one or more of live intestinal bacteria; genetically recombined, altered or modified, attenuated, chemically treated, physically treated, or inactivated intestinal bacteria; lysate of intestinal bacteria; and/or culture supernatant of intestinal bacteria. 
     In an embodiment, the tumor is a solid tumor.  
     Accordingly, another aspect relates to a composition for preventing and/or treating tumors, comprising any one or more of intestinal bacteria selected from a group consisting of  Alistipes shahii, Eubacterium ramulus, Eubacterium siraeum, Prevotella ruminicola, Ruminococcu lactaris, Anaerofustis stercorihominis, Clostridium nexile, Sanguibacteroides justesenii, Dorea formicigenerans , and  Bifidobacterium saeculare  as an active ingredient. 
     In an embodiment, the intestinal bacteria are any one or more of live intestinal bacteria; genetically recombined, altered or modified, attenuated, chemically treated, physically treated, or inactivated intestinal bacteria; lysate of intestinal bacteria; and/or culture supernatant of intestinal bacteria. 
     In an embodiment, the composition includes but is not limited to any one of a pharmaceutical composition, a food, a health product, or a food additive. 
     Another aspect relates to a method of promoting a proliferation of TCR γδ +  T cells and/or promoting an accumulation of CD8 positive cytotoxic T lymphocytes, and/or preventing and or treating tumors. 
     Another aspect relates to a method of stimulating a proliferation of TCR γδ +  T cells, and/or an accumulation of CD8 positive cytotoxic T lymphocytes, and/or preventing and/or treating tumors in a subject (for example, the subject in need thereof, for example, those in need of stimulating the accumulation of CD8 positive cytotoxic T lymphocytes, and/or the proliferation of TCR γδ +  T cells, and/or preventing and/or treating tumors). The method comprises the step of administrating the composition to a subject, wherein the composition comprises any one or more of intestinal bacteria selected from a group consisting of  Alistipes shahii, Eubacterium ramulus, Eubacterium siraeum, Prevotella ruminicola, Ruminococcu lactaris, Anaerofustis stercorihominis, Clostridium nexile, Sanguibacteroides justesenii, Dorea formicigenerans , and  Bifidobacterium saeculare  as an active ingredient. 
     More specifically, the method comprises the steps as follows: 
     (1) administrating a composition to a subject, wherein the composition comprises any one or more intestinal bacteria selected from a group consisting of  Alistipes shahii, Eubacterium ramulus, Eubacterium siraeum, Prevotella ruminicola, Ruminococcu lactaris, Anaerofustis stercorihominis, Clostridium nexile, Sanguibacteroides justesenii, Dorea formicigenerans , and  Bifidobacterium saeculare  as an active ingredient; 
     (2) stimulating an accumulation of CD8 positive cytotoxic T lymphocytes and/or a proliferation of TCR γδ +  T cells as follows:  
     administrating the composition every three days for stimulation, and then transplanting tumors ten days later, followed by further administrating the composition to measure the amount of CD8 positive cytotoxic T lymphocytes and TCR γδ +  T cells in the subject, wherein Day zero refers to the very first day for administrating the composition; and 
     (3) measuring the amount of CD8 positive cytotoxic T lymphocytes and TCR γδ +  T cells as follows: 
     detecting the proportion of CD8 T cells and TCR γδ+ T cells in culture cells by flow cytometry, with TCR y 6  and CD8 as molecular markers, wherein the CD8 positive T cell is characterized by the phenotype of CD 8   + and TCR γδ +  T cells is characterized by the phenotype of TCR γδ + . 
     According to the method, the measurement result of CD 8   + is used as an indicator for the proliferation or accumulation of CD8 positive cytotoxic T lymphocytes, and the measurement result of TCR γδ +  T is used as an indicator for the proliferation or accumulation of TCR γδ +  T cells. 
     The composition of the present disclosure comprises any one or more of ten types of intestinal bacteria as an active ingredient and it is an excellent composition for stimulating the accumulation or proliferation of CD8 positive cytotoxic T lymphocytes and/or TCR γδ +  T cells. Immunity in body can be increased through administering a pharmaceutical product that comprises the composition of the present disclosure, or taking foods or drinks that comprises the composition of the present disclosure. Therefore, the composition of the present disclosure can be used for such as preventing or treating infectious disease, autoimmune disease, or allergic disease, etc. In addition, if the composition of the present disclosure is comprised in the foods or drinks such as health food, healthy individuals can take the composition easily and routinely. Thus, it is possible to stimulate the accumulation or proliferation of CD8 positive cytotoxic T lymphocytes and/or TCR γδ +  T cells to improve the immunity. 
     BRIEF DESCRIPTION 
     Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein: 
       FIG. 1  depicts a schematic flow diagram of an experiment of ten types of intestinal bacteria for promoting an accumulation of CD8 positive cytotoxic T lymphocytes and/or TCR γδ +  T cells, and for treating tumors in a mouse model of liver cancer. Time is expressed in days (Day, d) for administrating the intestinal bacteria or transplanting tumor cells;  
       FIG. 2  depicts a statistical analysis graph of tumor sizes in three typical mice transplanted with liver cancer cells in each group, after intestinal bacteria (for example  Alistipes shahii , but intestinal bacteria being not limited to  Alistipes shahii ) are administrated; 
       FIG. 3  depicts an analysis graph of flow cytometry of CD8 positive cytotoxic T lymphocytes in one typical mouse in each group, after intestinal bacteria (for example  Alistipes shahii , but intestinal bacteria being not limited to  Alistipes shahii ) are administrated to mice transplanted with liver cancer cells, wherein right lower quadrant indicates CD8 positive cytotoxic T lymphocytes, and numerics in the right lower quadrant show the percentage of CD8 positive cytotoxic T lymphocytes in total cells in cecum; 
       FIG. 4  depicts a statistical analysis graph of the percentage of CD8 positive cytotoxic T lymphocytes in total cells in cecum, after intestinal bacteria (for example  Alistipes shahii , but intestinal bacteria being not limited to  Alistipes shahii ) are administrated to mice transplanted with liver cancer cells; 
       FIG. 5  depicts an analysis graph of flow cytometry of TCR γδ positive T lymphocytes in one typical mouse in each group, after intestinal bacteria (for example  Alistipes shahii , but intestinal bacteria being not limited to  Alistipes shahii ) are administrated to mice transplanted with liver cancer cells, wherein right lower quadrant indicates TCR γδ positive T lymphocytes, and numerics in the right lower quadrant show the percentage of TCR γδ positive T lymphocytes in total cells in cecum; 
       FIG. 6  depicts a statistical analysis graph of the percentage of TCR γδ positive T lymphocytes in total cells in cecum after intestinal bacteria (for example  Alistipes shahii , but intestinal bacteria being not limited to  Alistipes shahii ) are administrated to mice transplanted with liver cancer cells; and 
       FIG. 7  depicts a statistical analysis table showing tumor inhibitory rate, an increased percentage of CD8 positive cytotoxic T lymphocytes in tumor and an increased percentage of TCR γδ positive T lymphocytes in cecum, after ten types of intestinal bacteria are administrated to mice transplanted with liver cancer cells. 
    
    
     DETAILED DESCRIPTION 
     The present disclosure will be further described below with reference to the specific embodiments. It should be pointed out that ten types of intestinal bacteria (such as  Alistipes shahii ), or pharmaceutical compositions, foods, health products and food additives of the present disclosure comprising ten types of intestinal bacteria (such as  Alistipes shahii ) for promoting an  accumulation of CD8 positive cytotoxic T lymphocytes and/or a proliferation of TCR γδ +  T lymphocytes, can be applied to indications described above and exhibits the functions described above, after being administrated to a test subject. All dosage forms within the scope of the present disclosure have been tested, and only small parts of them are described hereinafter in the examples for illustration, however, they should not be understood as a limitation of embodiments of the invention. 
     The present disclosure provides a composition comprising any one or more of ten types of intestinal bacteria for promoting an accumulation of CD8 positive cytotoxic T lymphocytes and/or a proliferation of TCR γδ positive T lymphocytes, wherein the composition comprises at least one of ten types of live intestinal bacteria; ten types of genetically recombined, altered or modified, attenuated, chemically treated, physically treated, or inactivated intestinal bacteria; ten types of lysates of intestinal bacteria; and/or ten types of culture supernatants of intestinal bacteria as an active ingredient. 
     There is no specific limitation to “any one or more of ten types of intestinal bacteria, such as Alistipes shahii, etc” acting as an active ingredient of the composition described in the present disclosure, as long as the bacteria can be used for promoting an accumulation of CD8 positive cytotoxic T lymphocytes and/or a proliferation of TCR γδ positive T lymphocytes. The ten types of intestinal bacteria, such as  Alistipes shahii , etc, can be used individually in the composition of the present disclosure and can be combined with other bacteria excluding these bacteria as well. 
     In the disclosure, the “CD8 positive T cells” refers to T lymphocytes expressing CD8 to participate in immune response. The “γδ T cells” refers to T lymphocytes expressing TCR y chain and/or TCR δ chain to participate in immune response. 
     The present disclosure will be further described with embodiments as follows, but is not limited to the scope of the embodiments described herein. 
     Example 1 
     Culture of Intestinal Bacteria 
     1. Culture Method of  Alistipes shahii    
     Step 1: A cryopreserved  Alistipes shahii  strain (purchased from ATCC official website) was taken and then 200 uL of Trypticase Soy Agar (TSA) culture medium was added to redissolve it to obtain a bacterial solution. Subsequently, 20 uL of the bacterial solution was pipetted and streaked on a blood agar plate. After an air exhaustion processing by an anaerobic jar gassing system, the agar plate was placed in an incubator and incubated anaerobically at 37° C. for 48 h;  
     Step 2: A monoclonal colony was selected to inoculate in 10 mL of TSA culture medium, and incubated anaerobically at 37° C. for 12 h; 
     Step 3: 1% (v/v) of strains were inoculated in 500 ml of TSA culture medium in a flask, incubated anaerobically at 37° C. for 48 h; 
     Step 4: The bacterial solution was collected, and centrifuged at 6000 rpm for 10 min, washed twice with saline. Finally, the bacterial sludge was redissolved with saline for later use and viable bacteria were counted. 
     2. Culture method of  Eubacterium ramulus  or  Eubacterium siraeum    
     Step 1: A cryopreserved  Eubacterium  ( Eubacterium ramulus  or  Eubacterium siraeum ) strain (purchased from ATCC official website) was taken and 200 uL of TSA culture medium was added to redissolve it to obtain a bacterial solution. Subsequently, 20 uL of the bacterial solution was pipetted and streaked on a blood agar plate. After an air exhaustion processing by an anaerobic jar gassing system, the agar plate was placed in an incubator and incubated anaerobically at 37° C. for 48 h; 
     Step 2: A monoclonal colony was selected to inoculate in 10 mL of TSA culture medium, incubated anaerobically at 37° C. for 12 h; 
     Step 3: 1% (v/v) of strains were inoculated in 500 ml of TSA culture medium in a flask, and incubated anaerobically at 37° C. for 48 h; 
     Step 4: The bacterial solution was collected, and centrifuged at 6000 rpm for 10 min, washed twice with saline. Finally, the bacterial sludge was redissolved with saline for later use and viable bacteria were counted. 
     3. Culture method of  Prevotella ruminicola    
     Step 1: A cryopreserved  Prevotella ruminicola  strain (purchased from ATCC official website) was taken and 200 uL of TSA culture medium was added to redissolve it to obtain a bacterial solution. Subsequently, 20 uL of the bacterial solution was pipetted and streaked on a blood agar plate. After an air exhaustion processing by an anaerobic jar gassing system, the agar plate was placed in an incubator and incubated anaerobically at 37° C. for 48 h; 
     Step 2: A monoclonal colony was selected to inoculate in 10 mL of TSA culture medium, incubated anaerobically at 37° C. for 12 h; 
     Step 3: 1% (v/v) of strains were inoculated in 500 ml of TSA culture medium in a flask, and incubated anaerobically at 37° C. for 48 h;  
     Step 4: The bacterial solution was collected, and centrifuged at 6000 rpm for 10 min, washed twice with saline. Finally, the bacterial sludge was redissolved with saline for later use and viable bacteria were counted. 
     4. Culture Nethod of  Ruminococcu lactaris    
     Step 1: A cryopreserved  Ruminococcu lactaris  strain (purchased from ATCC official website) was taken and 200 uL of TSA culture medium was added to redissolve it to obtain a bacterial solution. Subsequently, 20 uL of the bacterial solution was pipetted and streaked on a blood agar plate. After an air exhaustion processing by an anaerobic jar gassing system, the agar plate was placed in an incubator and incubated anaerobically at 37° C. for 48 h; 
     Step 2: A monoclonal colony was selected to inoculate in 10 mL of TSA culture medium, incubated anaerobically at 37° C. for 12 h; 
     Step 3: 1% (v/v) of strains were inoculated in 500 ml of TSA culture medium in a flask, and incubated anaerobically at 37° C. for 48 h; 
     Step 4: The bacterial solution was collected, and centrifuged at 6000 rpm for 10 min, washed twice with saline. Finally, the bacterial sludge was redissolved with saline for later use and viable bacteria were counted. 
     5. Culture Method of  Anaerofustis stercorihominis    
     Step 1: A cryopreserved  Anaerofustis stercorihominis  strain (purchased from ATCC official website) was taken and 200 uL of TSA culture medium was added to redissolve it to obtain a bacterial solution. Subsequently, 20 uL of the bacterial solution was pipetted and streaked on a blood agar plate. After an air exhaustion processing by an anaerobic jar gassing system, the agar plate was placed in an incubator and incubated anaerobically at 37° C. for 48 h; 
     Step 2: A monoclonal colony was selected to inoculate in 10 mL of TSA culture medium, incubated anaerobically at 37° C. for 12 h; 
     Step 3: 1% (v/v) of strains were inoculated in 500 ml of TSA culture medium in a flask, and incubated anaerobically at 37° C. for 48 h; 
     Step 4: The bacterial solution was collected, and centrifuged at 6000 rpm for 10 min, washed twice with saline. Finally, the bacterial sludge was redissolved with saline for later use and viable bacteria were counted.  
     6. Culture Method of  Clostridium nexile    
     Step 1: A cryopreserved  Clostridium nexile  strain (purchased from ATCC official website) was taken and 200 uL of TSA culture medium was added to redissolve it to obtain a bacterial solution. Subsequently, 20 uL of the bacterial solution was pipetted and streaked on a blood agar plate. After an air exhaustion processing by an anaerobic jar gassing system, the agar plate was placed in an incubator and incubated anaerobically at 37° C. for 48 h; 
     Step 2: A monoclonal colony was selected to inoculate in 10 mL of TSA culture medium, incubated anaerobically at 37° C. for 12 h; 
     Step 3: 1% (v/v) of strains were inoculated in 500 ml of TSA culture medium in a flask, and incubated anaerobically at 37° C. for 48 h; 
     Step 4: The bacterial solution was collected, and centrifuged at 6000 rpm for 10 min, washed twice with saline. Finally, the bacterial sludge was redissolved with saline for later use and viable bacteria were counted. 
     7. Culture Method of  Sanguibacteroides justesenii    
     Step 1: A cryopreserved  Sanguibacteroides justesenii  strain (purchased from ATCC official website) was taken and 200 uL of TSA culture medium was added to redissolve it to obtain a bacterial solution. Subsequently, 20 uL of the bacterial solution was pipetted and streaked on a blood agar plate. After an air exhaustion processing by an anaerobic jar gassing system, the agar plate was placed in an incubator and incubated anaerobically at 37° C. for 48 h; 
     Step 2: A monoclonal colony was selected to inoculate in 10 mL of TSA culture medium, incubated anaerobically at 37° C. for 12 h; 
     Step 3: 1% (v/v) of strains were inoculated in 500 ml of TSA culture medium in a flask, and incubated anaerobically at 37° C. for 48 h; 
     Step 4: The bacterial solution was collected, and centrifuged at 6000 rpm for 10 min, washed twice with saline. Finally, the bacterial sludge was redissolved with saline for later use and viable bacteria were counted. 
     8. Culture Method of  Dorea formicigenerans    
     Step 1: A cryopreserved  Dorea formicigenerans  strain (purchased from ATCC official website) was taken and 200 uL of RGCA culture medium was added to redissolve it to obtain a bacterial solution. Subsequently, 20 uL of the bacterial solution was pipetted and streaked on a  blood agar plate. After an air exhaustion processing by an anaerobic jar gassing system, the agar plate was placed in an incubator and incubated anaerobically at 37° C. for 48 h; 
     Step 2: A monoclonal colony was selected to inoculate in 10 mL of RGCA culture medium, incubated anaerobically at 37° C. for 12 h; 
     Step 3: 1% (v/v) of strains were inoculated in 500 ml of RGCA culture medium in a flask, and incubated anaerobically at 37° C. for 48 h; 
     Step 4: The bacterial solution was collected, and centrifuged at 6000 rpm for 10 min, washed twice with saline. Finally, the bacterial sludge was redissolved with saline for later use and viable bacteria were counted. 
     9. Culture Method of  Bifidobacterium saeculare    
     Step 1: A cryopreserved  Bifidobacterium saeculare  strain (purchased from ATCC official website) was taken and 200 uL of Oxoid CM149 culture medium was added to redissolve it to obtain a bacterial solution. Subsequently, 20 uL of the bacterial solution was pipetted and streaked on a blood agar plate. After an air exhaustion processing by an anaerobic jar gassing system, the agar plate was placed in an incubator and incubated anaerobically at 37° C. for 48 h; 
     Step 2: A monoclonal colony was selected to inoculate in 10 mL of Oxoid CM149 culture medium, incubated anaerobically at 37° C. for 12 h; 
     Step 3: 1% (v/v) of strains were inoculated in 500 ml of Oxoid CM149 culture medium in a flask, and incubated anaerobically at 37° C. for 48 h; 
     Step 4: The bacterial solution was collected, and centrifuged at 6000 rpm for 10 min, washed twice with saline. Finally, the bacterial sludge was redissolved with saline for later use and viable bacteria were counted. 
     Example 2 
     An Experiment of the Above-Mentioned Intestinal Bacteria (For Example  Alistipes shahii , but Intestinal Bacteria Being not Limited to  Alistipes shahii ) for Stimulating an Expression of γδ TCR and a Proliferation of γδ T Lymphocytes, and Treating Tumors in Mice 
     1. Culture Method 
     A culture method of  Alistipes shahii  is the same as that in Example 1. 
     2. Sample Preparation 
     Preparation method of  Alistipes shahii  is the same as that in Example 1.  
     3. An experiment of an increased expression of γδ T lymphocytes in mice transplanted with liver tumors, stimulated by  Alistipes shahii    
       FIG. 1  is a schematic flow diagram of an experiment of detecting an increased proliferation of TCR γδ +  T lymphocytes in mice transplanted with liver tumor, stimulated by  Alistipes shahii.    
     Experimental animal: Eighteen C57BL/6 mice aged 3-4 weeks in a good mental state were purchased from the Experimental Animal Center of Sun Yat-sen University. The mice were randomly separated into two groups, 9 mice in each group, and the two groups were a control group and a live bacteria gavage group, respectively. The two groups of mice were administered with live  Ahstipes shahii  (10 9  CFU) and normal saline (the control group) by gavage for two weeks, respectively. After Hepa 1-6 mouse tumor (liver cancer) cells grew at logarithmic phase, the cells were digested with TE, and culture medium was neutralized. The cells were collected through centrifugation, and washed twice with DPBS to remove residual serum. After that, the cells were resuspended with DPBS. After the administration by gavage for about a week, the Hepa 1-6 mouse tumor (liver cancer) cells were counted. Subsequently, each mouse was subcutaneously inoculated with 10 6  cells into right axilla and continually treated by gavage, and then tumor-bearing mice were killed two weeks later. The size of tumors was statistically recorded, and the cells were collected, detected by using flow cytometry to analyze the amount of γδ T cells in cecum. 
     Example 3 
     Detection of the Amount of CD8 Positive T Cells by Using Flow Cytometry 
     (1) The tumor cells were collected into a flow tube with 10 7  cells in each tube, washed twice with PBS and centrifuged at 1500 rpm for 5 min, and then the cells were resuspended with 400 microliter of PBS after a removal of supernatant; 
     (2) An anti-CD8-FITC monoclonal antibody was added and mixed, and the tube was kept in a dark at 4° C. for 30 min; 
     (3) The cells were washed twice with PBS, centrifuged at 1500 rpm for 5 min, and then the cells were suspended with 400 microliter of PBS after a removal of supernatant; 
     (4) Single cell suspension was detected on a flow cytometry machine, wherein CD8 positive T cells were characterized by the phenotype of CD8 positive. 
     Example 4 
     Detection of the Amount of γδ T Cells by Using Flow Cytometry  
     (1) The cecum cells were collected into a flow tube with 10 7  cells in each tube, washed twice with PBS and centrifuged at 1500 rpm for 5 min, and then the cells were resuspended with 400 microliter of PBS after a removal of supernatant; 
     (2) An anti-TCRγδ-FITC monoclonal antibody was added and mixed, and the tube was kept in a dark at 4° C. for 30 min; 
     (3) The cells were washed twice with PBS, centrifuged at 1500 rpm for 5 min, and then the cells were suspended with 400 microliter of PBS after a removal of supernatant; 
     (4) Single cell suspension was detected on a flow cytometry machine, wherein γδ T cells is characterized by the phenotype of TCR γδ positive. 
     Analysis of Test Results 
       FIG. 1  shows a schematic flow diagram of an experiment of intestinal bacteria for treating tumors in a mice transplanted with liver cancer.  Alistipes shahii  is taken as an example, but the intestinal bacteria are not limited to  Alistipes shahii.    
     FIG 2  is a statistical analysis graph of tumor sizes in mice transplanted with liver cancer cells, after intestinal bacteria were administrated.  Alistipes shahii  is taken as an example, but the intestinal bacteria are not limited to  Alistipes shahii.    
     It is clearly observed from the results of  FIG. 2  that, compared with the control group (normal saline), the tumor sizes in mice transplanted with liver cancer cells are significantly decreased by about 63% after  Alistipes shahii  was administrated, and the decrease represents statistically significant difference (p&lt;0.001). Therefore, the administration of  Alistipes shahii  for treating the mice can significantly inhibit tumor growth. In other examples, it can also be observed that the tumor sizes are significantly decreased after the above-mentioned other nine types of intestinal bacteria were administrated, and the decrease represents statistically significant difference (p&lt;0.005 to 0.05). 
     In other examples (experimental procedures and conditions are the same as above), tumor inhibitory rate of  Eubacterium ramulus  is about 45 to 60%, tumor inhibitory rate of  Eubacterium siraeum  is about 30 to 65%, tumor inhibitory rate of  Prevotella ruminicola  is about 40 to 50%, tumor inhibitory rate of  Ruminococcu lactaris  is about 50 to 60%, tumor inhibitory rate of  Anaerofustis stercorihominis  is about 45 to 65%, tumor inhibitory rate of  Clostridium nexile  is about 35 to 65%, tumor inhibitory rate of  Sanguibacteroides justesenii  is about 40 to 60%, tumor inhibitory rate of  Dorea formicigenerans  is about 50 to 75%, and tumor inhibitory rate of  Bifidobacterium saeculare  is about 35 to 80%,  
     Thus, all of the above-mentioned intestinal bacteria have a significant inhibitory effect on tumor growth. 
       FIG. 3  is an analysis graph of flow cytometry of CD8 positive cytotoxic T lymphocytes for one typical mouse in each group in transplanted liver cancer cell microenvironment after the intestinal bacteria (for example  Alistipes shahii , but intestinal bacteria being not limited to  Alistipes shahii ) are administrated to liver tumors in mice transplanted with liver cancer cells, wherein numerics in the right lower quadrant show the percentage of CD8 positive T lymphocytes in total cells in cecum.  Alistipes shahii  is taken as an example to obtain the statistical analysis graph of flow cytometry, but intestinal bacteria are not limited to  Alistipes shahii.    
     It can be seen from the analysis graph of flow cytometry that, compared with the control group (normal saline),  Alistipes shahii  increases a relative amount of CD8 +  T lymphocytes by about 70% in liver tumor microenvironment. 
       FIG. 4  is a statistical analysis graph of the percentage of CD8 positive T lymphocytes in cells in tumor microenvironment of mice transplanted with liver cancer, three mice in each group. 
     It can be seen from the statistical analysis graph that, compared with the control group (pure water),  Alistipes shahii  increases a relative amount of CD8 +  T lymphocytes in tumor microenvironment, and the increase represents statistically significant difference (p&lt;0.001). 
     In other examples, the following nine types of intestinal bacteria,  Eubacterium ramulus, Eubacterium siraeum, Prevotella ruminicola, Ruminococcu lactaris, Anaerofustis stercorihominis, Clostridium nexile, Sanguibacteroides justesenii, Dorea formicigenerans , and  Bifidobacterium saeculare  increase the percentage of CD8 positive T lymphocytes by about 55%, about 61%, about 58%, about 59%, about 55%, about 65%, about 62%, about 49%, and about 50%, respectively. Therefore, all the above-mentioned intestinal bacteria significantly increase a relative amount of CD 8   +  T lymphocytes in tumor microenvironment, and the increase represents statically significant difference (p&lt;0.001 to 0.05). 
       FIG. 5  is an analysis graph of flow cytometry of TCR γδ positive T lymphocytes in cecum in one typical mouse in each group, after the intestinal bacteria (for example  Alistipes shahii , but intestinal bacteria being not limited to  Alistipes shahii ) are administrated to liver tumors in mice transplanted with liver cancer cells, wherein numerics in the right lower quadrant show the percentage of TCR γδ positive T lymphocytes in cecum cells.  
     It can be seen from the statistical analysis graph that, compared with the control group (normal saline),  Alistipes shahii  increases a relative amount of TCR γδ positive T lymphocytes by about 48% in liver tumor microenvironment. 
     FIG. 6 is a statistical analysis graph of the percentage of TCR γδ positive T lymphocytes in cecum cells after the intestinal bacteria are administrated to mice transplanted with liver cancer cells, three mice in each group. 
     It can be seen from the statistical analysis graph that, compared with the control group (pure water),  Alistipes shahii  significantly increases a relative amount of TCR γδ +  T lymphocytes in cecum, and the increase represents statistically significant difference (p&lt;0.001).  Alistipes shahii  is taken as an example to obtain the statistical analysis graph of flow cytometry, but intestinal bacteria are not limited to  Alistipes shahii.    
     In other examples, the following nine types of intestinal bacteria,  Eubacterium ramulus, Eubacterium siraeum, Prevotella ruminicola, Ruminococcu lactaris, Anaerofustis stercorihominis, Clostridium nexile, Sanguibacteroides justesenii, Dorea formicigenerans , and  Bifidobacterium saeculare  increase the percentage of TCR γδ positive T lymphocytes by about 25%, about 34%, about 26%, about 22%, about 44%, about 52%, about 33%, about 30%, and about 31%, respectively. Therefore, all the above-mentioned intestinal bacteria significantly increase a relative amount of TCR γδ +  T lymphocytes in cecum, and the increase represents statically significant difference (p&lt;0.001 to 0.05). 
     In the statistical analysis graph, * represents student t-test at p&lt;0.05, ** represents student t-test at p&lt;0.01. *** represents student t-test at p&lt;0.0001. p&lt;0.05 represents statistically significant difference. 
     In conclusion, ten types of intestinal bacteria used in the present disclosure have a significant inhibiting effect on tumor growth, and they significantly inhibit formation and growth of tumor in mice transplanted with liver cancer cells ( FIG. 2 ). It can be seen from the experiments of  FIGS. 3, 4, 5, 6 and 7  that, compared with the control group (normal saline), the live bacteria gavage group significantly increases the infiltration of CD8 positive cytotoxic T lymphocytes in tumor microenvironment and increases the accumulation of TCR γδ +  T lymphocytes in cecum, thereby significantly inhibiting tumor growth and having a good effect on the prevention and treatment of tumors.  
     Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention. 
     For the sake of clarity, it is to be understood that the use of ‘a’ or ‘an’ throughout this application does not exclude a plurality, and ‘comprising’ does not exclude other steps or elements.