Bifidobacterium lactis BA-C44 and application thereof in relieving symptoms of ulcerative colitis

Abstract

The invention discloses bifidobacterium lactis BA-C44 and application of the bifidobacterium lactis BA-C44 in relieving ulcerative colitis symptoms, the bifidobacterium lactis BA-C44 is preserved in the China Center for Type Culture Collection on December 04, 2023, and the preservation number is CCTCC NO: M 2023447. A product prepared from the bifidobacterium lactis BA-C44 disclosed by the invention has the beneficial effect of relieving symptoms of ulcerative colitis. Besides, the bifidobacterium lactis BA-C44 has good temperature tolerance and gastrointestinal fluid tolerance, is convenient for storage of commercial products after preparation, is easier to survive in intestines and stomach, and achieves the purpose of relieving symptoms of ulcerative colitis, so that the bifidobacterium lactis BA-C44 has a good application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of microorganisms, and in particular to Bifidobacterium lactis BA-C44 and application thereof in alleviating the symptoms of ulcerative colitis. Background Art

[0002] Ulcerative colitis (UC) is an ulcerative, recurrent intestinal disease characterized by inflammation and ulceration of the colon mucosa, often accompanied by abdominal pain, diarrhea, rectal bleeding, weight loss and other symptoms, which seriously affect the quality of life of patients. Studies have shown that UC is associated with intestinal microbial dysbiosis, which activates the innate and host adaptive immune systems, leading to chronic inflammation. Commonly used drugs for the treatment of ulcerative colitis are generally immunosuppressive drugs, biological agents and antibiotics, among which 5-aminosalicylic acid (5-ASA) and its derivatives are the main drugs for the treatment of UC, but adverse reactions such as diarrhea, abdominal pain, headache and nasopharyngitis may occur during treatment. Studies have shown that some probiotics such as those belonging to the genera Lactobacillus, Bifidobacterium and Saccharomyces cerevisiae can relieve ulcerative colitis by inhibiting pathogenic bacteria, improving epithelial and mucosal barrier function, regulating immune responses and / or changing the composition of intestinal microbiota. Compared with conventional therapies and monotherapy, which have varying degrees of side effects and limitations, probiotics are considered a promising and beneficial strategy in the prevention and treatment of UC due to their therapeutic efficacy and few side effects.

[0003] Bifidobacterium animalis subsp.lactis is a kind of probiotics that has a positive effect on the health of the body. Studies have found that Bifidobacterium lactis not only has good gastric acid and bile tolerance, intestinal mucosal adhesion characteristics, but also has the functions of inhibiting pathogen proliferation, strengthening intestinal barrier, improving body immunity, regulating intestinal microbial population and reducing cholesterol, and can effectively prevent and treat ulcerative colitis disease. However, the adaptability of known Bifidobacterium lactis to temperature changes is relatively low, so when it is applied to commercial products, there are limitations to the preservation of products. In addition, it is known that Bifidobacterium lactis has a relatively low tolerance to gastric juice and intestinal juice, and is easily inactivated when passing through the gastrointestinal tract, so that it is possible to reach the human colon to play a role in alleviating the symptoms of ulcerative colitis. There are fewer live bacteria. Therefore, studying Bifidobacterium lactis will open up new ways for the prevention and treatment of ulcerative colitis, and provide new ideas and methods for the research of related fields. Summary of the invention

[0004] The object of the present invention is to provide a kind of Bifidobacterium lactis BA-C44 and its application in relieving the symptoms of ulcerative colitis. The product prepared by the Bifidobacterium lactis BA-C44 of the present invention has the beneficial effect of relieving the symptoms of ulcerative colitis. In addition, the Bifidobacterium lactis BA-C44 of the present invention has good temperature tolerance and gastrointestinal fluid tolerance, which is convenient for the storage of commercial products after preparation, and achieves the purpose of relieving the symptoms of ulcerative colitis.

[0005] The technical solution of the present invention: a Bifidobacterium lactis BA-C44, wherein the animal Bifidobacterium lactis subspecies BA-C44 has been deposited in the China Center for Type Culture Collection on December 4, 2023, with the deposit number: CCTCC NO: M 20232447.

[0006] The use of the above-mentioned Bifidobacterium lactis BA-C44 in the preparation of a product for relieving the symptoms of ulcerative colitis.

[0007] In the aforementioned application, the product is food, medicine and / or health product.

[0008] In the aforementioned application, the food is one or more of fermented milk, cheese, milk-containing beverage, solid beverage, and milk powder; the food contains inactivated bacteria, live bacteria powder, and / or heat-inactivated bacteria powder of Bifidobacterium lactis BA-C44.

[0009] In the aforementioned application, the medicine comprises inactivated bacteria, live bacteria powder and / or heat-inactivated bacteria powder of Bifidobacterium lactis BA-C44, and / or other medicines compatible with the inactivated bacteria, live bacteria powder and / or heat-inactivated bacteria powder of Bifidobacterium lactis BA-C44, as well as pharmaceutically acceptable carriers and / or excipients.

[0010] In the aforementioned application, the relief of ulcerative colitis symptoms includes relief of weight loss, colon shortening and colon tissue lesions.

[0011] In the aforementioned application, the relief of the symptoms of ulcerative colitis includes lowering the spleen index and increasing the thymus index.

[0012] In the aforementioned application, the relief of ulcerative colitis symptoms includes inhibiting the excessive inflammatory markers IL-8, TNF-α and / or IFN-γ produced by the body, and promoting the expression of the anti-inflammatory cytokine IL-10.

[0013] The application of the above-mentioned Bifidobacterium lactis BA-C44 in the preparation of a product that inhibits the IL-8, TNF-α and / or IFN-γ signaling pathways and activates the anti-inflammatory cytokine IL-10.

[0014] The aforementioned Bifidobacterium lactis BA-C44, its strain culture method comprises the following steps:

[0015] (1) Preparation of MRS medium: Prepare raw materials according to 20 g / L glucose, 10 g / L peptone, 5 g / L yeast extract, 10 g / L beef extract, 1 mL Tween-80, 2 g / L dipotassium hydrogen phosphate, 2 g / L diammonium citrate, 5 g / L sodium acetate, 0.58 g / L magnesium sulfate heptahydrate, and 0.25 g / L manganese sulfate tetrahydrate, mix them evenly, dissolve the obtained mixture in deionized water, and sterilize the obtained solution at a temperature of 121° C. for 20 min to obtain the MRS medium;

[0016] (2) Cultivation of strains: Live bacterial powder of Bifidobacterium lactis BA-C44 was streaked into the MRS medium of step 1 containing 2% agar, and cultured anaerobically at 37°C for 48 h. A single colony was picked and inoculated into MRS liquid medium and cultured anaerobically at 37°C for 18 h.

[0017] Compared with the prior art, the present invention's Bifidobacterium lactis BA-C44 can alleviate ulcerative colitis symptoms, wherein its inactivated bacteria, live bacteria type or heat-inactivated type powder can alleviate DSS-induced Balb / c mouse weight loss, can significantly improve the blood in stool situation of DSS-induced ulcerative colitis mice and reduce its DAI score, improve the thymus index of mice, reduce the spleen index of mice, alleviate the shortening of colon length and colon histological lesions, can simultaneously downregulate the production of serum proinflammatory factors IL-8, TNF-α and IFN-γ by cellular immunity, increase the expression of anti-inflammatory factor IL-10. The live thalline of the present invention's Bifidobacterium lactis BA-C44 has good temperature tolerance and gastrointestinal fluid tolerance, therefore in commercial applications, convenient for commercial product preparation after preservation, also easier to survive through the stomach and small intestine after oral administration or eating, reach the purpose of alleviating ulcerative colitis symptoms, therefore the present invention's Bifidobacterium lactis BA-C44 has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The live bacterial powder (C44) and heat-killed bacterial powder (IC44) of Bifidobacterium lactis BA-C44 alleviated the weight loss of mice with DSS-induced ulcerative colitis.

[0019] Figure 2 The live bacterial powder (C44) and heat-killed bacterial powder (IC44) of Bifidobacterium lactis BA-C44 improve the bloody stool in mice with ulcerative colitis.

[0020] Figure 3 The effects of live bacterial powder (C44) and heat-killed bacterial powder (IC44) of Bifidobacterium lactis BA-C44 on the DAI scores of mice with DSS-induced ulcerative colitis.

[0021] Figure 4The effects of live bacterial powder (C44) and heat-killed bacterial powder (IC44) of Bifidobacterium lactis BA-C44 on the thymus and spleen indexes of mice with DSS-induced ulcerative colitis were studied.

[0022] Figure 5 The effects of live bacterial powder (C44) and heat-killed bacterial powder (IC44) of Bifidobacterium lactis BA-C44 on colon length in mice with DSS-induced ulcerative colitis.

[0023] Figure 6 The effects of live bacterial powder (C44) and heat-killed bacterial powder (IC44) of Bifidobacterium lactis BA-C44 on colon histological lesions in mice with DSS-induced ulcerative colitis.

[0024] Figure 7 The effect of live bacterial powder (C44) and heat-killed bacterial powder (IC44) of Bifidobacterium lactis BA-C44 on the mRNA content of cytokines IL-8, IL-10, TNF-α and IFN-γ in the colon tissue of mice with DSS-induced ulcerative colitis was studied.

[0025] Figure 8 The effect of live bacterial powder (C44) and heat-killed bacterial powder (IC44) of Bifidobacterium lactis BA-C44 on the levels of cytokines IL-8, IL-10, TNF-α and IFN-γ in the serum of mice with DSS-induced ulcerative colitis was studied. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0027] Example 1: Screening and identification of Bifidobacterium lactis

[0028] A strain of Bifidobacterium animalis subsp. Lactis BA-C44 was isolated and screened from the feces of a healthy child. The strain was identified by bacterial morphology, physiology and culture characteristics combined with 16S rDNA sequencing. The strain belongs to Bifidobacterium (Bifidobacterium) and is presumed to be Bifidobacterium animalis (animal Bifidobacterium) and Bifidobacterium animalis subsp. Lactis (animal Bifidobacterium lactis subsp. Lactis). Therefore, it was named Bifidobacterium animalis subsp. Lactis BA-C44. It has been deposited in the China Center for Type Culture Collection on December 4, 2023, with the deposit number: CCTCC NO: M 20232447. The sequenced DNA sequence is as follows:

[0029] CGTGGGGGGCCTGCTGTCGGGGTGAGAGTGGCGACGGGTGAGTAATGCGTGACC

[0030] AACCTGCCCTGTGCACCGGAATAGCTCCTGGAAACGGGTGGTAATACCGGATGCTCCG

[0031] CTCCATCGCATGGTGGGGTGGGAAATGCTTTTGCGGCATGGGATGGGGTCGCGTCCTA

[0032] TCAGCTTGTTGGCGGGGTGATGGCCCACCAAGGCGTTGACGGGTAGCCGGCCTGAGAG

[0033] GGTGACCGGCCACATTGGGACTGAGATACGGCCCAGACTCCTACGGGAGGCAGCAGTG

[0034] GGGAATATTGCACAATGGGCGCAAGCCTGATGCAGCGACGCCGCGTGCGGGATGGAGG

[0035] CCTTCGGGTTGTAAACCGCTTTTGTTCAAGGGCAAGGCACGGTTTCGGCCGTGTTGAG

[0036] TGGATTGTTCGAATAAGCACCGGCTAACTACGTGCCAGCAGCCGCGGTAATACGTAGG

[0037] GTGCGAGCGTTATCCGGATTTATTGGGCGTAAAGGGCTCGTAGGCGGTTCGTCGCGTC

[0038] CGGTGTGAAAGTCCATCGCCTAACGGTGGATCTGCGCCGGGTACGGGCGGGCTGGAGT

[0039] GCGGTAGGGGAGACTGGAATTCCCGGTGTAACGGTGGAATGTGTAGATATCGGGAAGA

[0040] ACACCAATGGCGAAGGCAGGTCTCTGGGCCGTCACTGACGCTGAGGAGCGAAAGCGTG

[0041] GGGAGCGAACAGGATTAGATACCCTGGTAGTCCACGCCGTAAACGGTGGATGCTGGAT

[0042] GTGGGGCCCTTTCCACGGGTCCCGTGTCGGAGCCAACGCGTTAAGCATCCCGCCTGGG

[0043] GAGTACGGCCGCAAGGCTAAAACTCAAAGAAATTGACGGGGGCCCGCACAAGCGGCGG

[0044] AGCATGCGGATTAATTCGATGCAACGCGAAGAACCTTACCTGGGCTTGACATGTGCCG

[0045] GATCGCCGTGGAGACACGGTTTCCCTTCGGGGCCGGTTCACAGGTGGTGCATGGTCGT

[0046] CGTCAGCTCGTGTCGTGAGATGTTGGGTTAAGTCCCGCAACGAGCGCAACCCTCGCCG

[0047] CATGTTGCCAGCGGGTGATGCCGGGAACTCATGTGGGACCGCCGGGGTCAACTCGGAG

[0048] GAAGGTGGGGATGACGTCAGATCATCATGCCCCTTACGTCCAGGGCTTCACGCATGCT

[0049] ACAATGGCCGGTACAACGCGGTGCGACACGGTGACGTGGGGCGGATCGCTGAAAACCG

[0050] GTCTCAGTTCGGATCGCAGTCTGCAACTCGACTGCGTGAAGGCGGAGTCGCTAGTAAT

[0051] CGCGGATCAGCAACGCCGCGGTGAATGCGTTCCCGGGCCTTGTACACACCGCCCGTCA

[0052] AGTCATGAAAGTGGGTAGCACCCGAAGCCGGTGGCCCGACCCTTGTGGGGGGAGCCGT

[0053] CTAAGGTGAGAACCTCCGGGTAAGGGTA

[0054] Example 2: Strain culture

[0055] The live bacteria powder of Bifidobacterium lactis BA-C44 of the present invention is cultured and activated in MRS medium, and the specific steps are as follows:

[0056] a. Strain culture method:

[0057] (1) Preparation of MRS medium

[0058] The raw materials are prepared according to 20 g / L glucose, 10 g / L peptone, 5 g / L yeast extract, 10 g / L beef extract, 1 mL Tween-80, 2 g / L dipotassium hydrogen phosphate, 2 g / L diammonium citrate, 5 g / L sodium acetate, 0.58 g / L magnesium sulfate heptahydrate, and 0.25 g / L manganese sulfate tetrahydrate, and the raw materials are mixed uniformly, and the obtained mixture is dissolved in deionized water, and the obtained solution is sterilized at a temperature of 121° C. for 20 min to obtain the MRS medium.

[0059] (2) Culture of strains

[0060] The live bacterial powder of Bifidobacterium lactis BA-C44 was streaked into the medium of step (1) containing 2% agar and cultured anaerobically at 37°C for 48h. A single colony was picked and inoculated into MRS liquid medium and cultured anaerobically at 37°C for 18h.

[0061] (3) Heat inactivation

[0062] The cultured Bifidobacterium lactis BA-C44 was sterilized at 121°C for 20 min and cooled to room temperature for animal experiments.

[0063] Example 3: Evaluation of strain tolerance:

[0064] Bifidobacterium lactis BA-C44 was used as the research object to conduct temperature tolerance and simulated gastrointestinal tolerance experiments, and Bifidobacterium lactis BL-99 and Bifidobacterium lactis HN019 were used as comparative examples.

[0065] (1) Temperature tolerance experiment: Powders of Bifidobacterium lactis BA-C44, Bifidobacterium lactis BL-99 and Bifidobacterium lactis HN019 were prepared into bacterial suspensions in sterile saline; the bacterial suspensions were treated at 4°C, 37°C, 45°C, 50°C and 80°C for 30 min, and then the number of viable bacteria in the bacterial suspensions after different heat treatments was determined by the plate count method.

[0066] (2) Tolerance test in gastrointestinal fluid: simulated human gastrointestinal fluid was prepared, and Bifidobacterium lactis BA-C44, Bifidobacterium lactis BL-99 and Bifidobacterium lactis HN019 were treated in the simulated gastrointestinal fluid for different periods of time; the plate count method was used to determine the number of live bacteria of Bifidobacterium lactis BA-C44, Bifidobacterium lactis BL-99 and Bifidobacterium lactis HN019 after treatment in the simulated gastrointestinal fluid.

[0067] Preparation of simulated gastric juice: Use PBS at pH 2.5 to prepare a pepsin solution with a concentration of 3 mg / mL, i.e. artificial gastric juice, which is filtered and sterilized through a 0.22 μm microporous filter membrane for later use.

[0068] Preparation of simulated intestinal fluid: Prepare a trypsin solution with a concentration of 1 mg / mL using PBS at pH 8.0, add ox bile salt to make the final concentration of 1.8%, the obtained solution is the artificial intestinal fluid, and filter it through a 0.22 μm microporous filter membrane for sterilization before use.

[0069] Add sterile PBS (pH 7.3) to the powders of Bifidobacterium lactis BA-C44, Bifidobacterium lactis BL-99 and Bifidobacterium lactis HN019, shake to resuspend them, take 500 μL of the resuspended solution and add it to 4.5 mL of artificial gastric juice, incubate in a 37°C incubator for 3 hours, and count by pouring plate method. Then take 500 μL of the bacterial suspension incubated in artificial gastric juice for 3 hours and add it to 4.5 mL of artificial intestinal juice, incubate in a 37°C incubator for 8 hours, and count by pouring plate method. Calculate the survival rate according to the following formula.

[0070] Survival rate = number of colonies after treatment (CFU / mL) / initial number of colonies (CFU / mL) × 100%.

[0071] Table 1: Temperature tolerance of Bifidobacterium lactis BA-C44, Bifidobacterium lactis BL-99 and Bifidobacterium lactis HN019

[0072]

[0073] It can be seen from the table that there is no significant difference in the number of live bacteria of the strain Bifidobacterium lactis BA-C44 when treated at 37°C, but as the temperature increases and decreases, the number of live bacteria of the strain Bifidobacterium lactis BA-C44 shows a downward trend, but the overall downward trend is slow, showing good temperature tolerance. Compared with Bifidobacterium lactis BL-99 and Bifidobacterium lactis HN019, it has significant temperature tolerance.

[0074] Table 2: Gastrointestinal tolerability of Bifidobacterium lactis C44, Bifidobacterium lactis BL-99 and Bifidobacterium lactis HN019

[0075]

[0076] It can be seen from the table that the viable bacterial survival rate of Bifidobacterium lactis C44 can still be maintained at 37.56% after 3 hours in gastric juice, and the viable bacterial survival rate can reach 73.10% after 8 hours of culture in intestinal fluid, indicating that Bifidobacterium lactis BA-C44 has good gastrointestinal tolerance and has significant tolerance to simulated gastrointestinal fluid compared with Bifidobacterium lactis BL-99 and Bifidobacterium lactis HN019.

[0077] Example 4: Prevention, treatment and relief of inflammation in mice with ulcerative colitis by using Bifidobacterium lactis BA-C44 bacterial powder

[0078] 1. Animal Grouping

[0079] Eight-week-old male Babl / c mice were randomly divided into blank group (NC), model group (DSS), drug treatment group (5-ASA), live bacteria group (C44) and heat-inactivated group (IC44) after one week of adaptive feeding. The mice in the normal group were gavaged with normal saline every day, and they could freely drink normal drinking water after 7 days. The mice in the model group and drug treatment group were gavaged with normal saline every day, and they could freely drink 3% dextran sodium sulfate aqueous solution (DSS) after 7 days. The live bacteria group of Bifidobacterium lactis BA-C44 (C44) was gavaged with 0.2mL 1.5×109CFU / mL target strain saline suspension every day, and the heat-inactivated group (IC44) was gavaged with 0.2mL 1.5×109CFU / mL heat-inactivated target strain saline suspension every day, and they could freely drink 3% dextran sodium sulfate aqueous solution (DSS) after 7 days. The experiment lasted for 3 weeks in total.

[0080] 2. Effect of Bifidobacterium lactis BA-C44 powder on body weight of colitis mice

[0081] By recording the weight changes of mice every day since the beginning of the experiment, the results are as follows Figure 1 As shown, the results showed that the oral administration of live bacteria group and the heat-killed group had a certain effect in slowing down the weight loss of mice.

[0082] 3. Effect of Bifidobacterium lactis BA-C44 powder on inflammatory response in colitis mice

[0083] The blood in the stool of mice was recorded by taking photos. Figure 2As shown, the results showed that the mice after DSS drinking water showed acute phase performance compared with the normal group. On the third day of DSS modeling, the stool of mice was loose, and some mice had blood in the stool. On the fourth day, the stool was seriously unformed, some had loose stools, and most had blood in the stool. On the fifth day, the mice had less food and water, lost weight, had blood in the stool, diarrhea, curled up in piles, were listless, and had dull fur. The mental state of the mice in the gavage live bacteria group and the inactivated group was significantly improved compared with the model group. After the mice were dissected, it was found that the colon of the blank control group mice was light red, and formed feces could be seen in the intestine; the colon of the mice in the DSS model group was black, with severe bleeding and congestion, and the adhesion of intestinal organs was difficult to separate. In severe cases, the colon segment contained bloody contents; the colon color of the mice in the gavage live bacteria group and the heat-inactivated group was lighter than that of the DSS model group, and some formed feces could be seen. The congestion and bloody intestinal contents were reduced compared with the DSS model group. It shows that gavage of live Bifidobacterium lactis BA-C44 bacteria and heat inactivation have significantly improved the blood in the stool of mice caused by DSS.

[0084] 4. Effect of Bifidobacterium lactis BA-C44 powder on DAI in colitis mice

[0085] Referring to Table 3, the DAI score of mice was calculated by recording the weight change, blood in stool and stool characteristics of mice every day since the start of the experiment.

[0086] Table 3: DAI score

[0087]

[0088] The DSS-induced colitis mouse model showed obvious characteristics of diarrhea, loose stools, and bloody stools, leading to a significant increase in the DAI score. Figure 3 As shown in the figure, on the 11th day of the experiment (4 days after DSS modeling), DSS modeling caused a decrease in the DAI of mice. The DAI scores of mice were scored based on their weight, feces and rectal bleeding. During the DSS administration period, the DAI scores of mice showed an increasing trend. Visible blood in the stool appeared on the 4th day, and the DAI scores reached the maximum value on days 5-7. The results showed that the oral administration of live Bifidobacterium lactis BA-C44 and the heat-killed group had a slowing trend in the increase in the DAI scores of mice caused by DSS.

[0089] 5. Effect of Bifidobacterium lactis BA-C44 powder on thymus index and spleen index of colitis mice

[0090] After killing the mice, the thymus and spleen were taken out and weighed and recorded. The experimental results are as follows: Figure 4As shown in the results, compared with the DSS-induced colitis mice, the model mice injected with live Bifidobacterium lactis BA-C44 and heat-killed groups significantly reduced the spleen index and increased the thymus index. Therefore, it is believed that Bifidobacterium lactis BA-C44 and its metabolites have the function of alleviating the immune disorder of mice caused by DSS.

[0091] The above results indicate that Bifidobacterium lactis BA-C44 effectively alleviates the symptoms of ulcerative colitis.

[0092] Example 5: Bifidobacterium lactis BA-C44 powder improves colon damage in DSS colitis mice

[0093] Based on Example 4, mice were killed after 21 days and their colons were measured for length. Figure 5 As shown, the length of the mouse colon was significantly shortened after DSS modeling, the pentaaminosalicylic acid treatment group significantly restored the colon length of the mice; the Bifidobacterium lactis BA-C44 group and the heat-killed group partially restored the colon length of the mice.

[0094] Example 6: Bifidobacterium lactis BA-C44 powder improves colon histological lesions in mice with DSS colitis

[0095] Based on Example 4, the mouse colon was obtained after being killed, fixed, embedded, sliced ​​and stained with H&E using 4% paraformaldehyde. Figure 6 As shown in the figure, compared with the model group, the large-area edema in the colon of mice in the oral administration of Bifidobacterium lactis BA-C44 and heat-killed group disappeared significantly, and the degree of crypt structure damage was significantly reduced. This indicates that oral administration of Bifidobacterium lactis BA-C44 and heat-killed group has an alleviating effect on colitis.

[0096] Example 7: Effects of Bifidobacterium lactis BA-C44 on inflammatory factors in mice with DSS-induced colitis

[0097] Based on Example 4, the mouse colon was obtained after being killed, and was quickly frozen with liquid nitrogen and then stored in a -80°C refrigerator for later use. Figure 7 RT-qPCR results showed that compared with the control group, the DSS-induced enteritis mouse model group significantly enhanced the expression of IL-8, TNF-α and IFN-γ mRNA, and reduced the expression of IL-10 mRNA (p<0.05); compared with the model group, the oral administration of live Bifidobacterium lactis BA-C44 bacteria group and the heat-killed group, the expression of IL-8, TNF-α and IFN-γ mRNA was significantly reduced (p<0.05), and the expression of IL-10 mRNA was significantly increased. This shows that live Bifidobacterium lactis BA-C44 bacteria and its metabolites have anti-inflammatory biological functions and alleviate the damage of the intestinal immune barrier.

[0098] Example 8: Bifidobacterium lactis BA-C44 regulates cellular immunity and alleviates DSS colitis

[0099] Before killing the mice, blood was collected from the eyeballs, and the expression levels of IL-8, IL-10, TNF-α, and IFN-γ in the serum were detected using ELISA kits. Figure 8 As shown in the figure, compared with the model group mice, the Bifidobacterium lactis BA-C44 group and the heat-inactivated group significantly upregulated the expression level of the anti-inflammatory cytokine IL-10, and downregulated the expression levels of the pro-inflammatory cytokines IL-8, TNF-α and IFN-γ. This indicates that Bifidobacterium lactis BA-C44 intervention in mice can alleviate DSS-induced colitis in mice through cellular immunity.

[0100] It can be seen from the above experiments that the live bacteria of Bifidobacterium lactis BA-C44 of the present invention have a high temperature tolerance; the live bacteria and heat-killed bacterial powders can alleviate the weight loss of DSS-induced Balb / c mice, can significantly improve the bloody stools of DSS-induced ulcerative colitis mice and reduce their DAI scores, increase the thymus index of mice, reduce the spleen index of mice, alleviate the shortening of colon length and colon histological lesions, downregulate the production of serum proinflammatory factors IL-8, TNF-α and IFN-γ through cellular immunity, and increase the expression of anti-inflammatory factor IL-10. It can be seen that the Bifidobacterium lactis BA-C44 described in the present invention can relieve ulcerative colitis, so the Bifidobacterium lactis BA-C44 described in the present invention can be used in the preparation of a food composition and / or a pharmaceutical composition for relieving the symptoms of ulcerative colitis, wherein the food composition contains inactivated bacteria, live bacteria powder and / or heat-inactivated bacteria powder of Bifidobacterium lactis BA-C44, including but not limited to one or more of fermented milk, cheese, milk-containing beverages, solid beverages, and milk powder; the pharmaceutical composition contains inactivated bacteria, live bacteria powder and / or heat-inactivated bacteria powder of Bifidobacterium lactis BA-C44, and / or other drugs compatible with the inactivated bacteria, live bacteria powder and / or heat-inactivated bacteria powder of Bifidobacterium lactis BA-C44, as well as pharmaceutically acceptable carriers and / or excipients.

[0101] The above descriptions are only some preferred embodiments of the present disclosure and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the embodiments of the present disclosure is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the above-mentioned inventive concept. For example, the above-mentioned features are replaced with the technical features with similar functions disclosed in the embodiments of the present disclosure (but not limited to) and the technical solutions formed.

Claims

1. A Bifidobacterium lactis BA-C44, characterized in that: The Bifidobacterium lactis BA-C44 was deposited in the China Center for Type Culture Collection on December 4, 2023, with the deposit number: CCTCC NO: M 20232447.

2. Use of Bifidobacterium lactis BA-C44 according to claim 1 in the preparation of a product for alleviating the symptoms of ulcerative colitis.

3. The use according to claim 2, characterized in that: The products are foods, medicines and / or health products.

4. The use according to claim 3, characterized in that: The food is one or more of fermented milk, cheese, milk-containing beverage, solid beverage, and milk powder; the food contains inactivated bacteria, live bacteria powder, and / or heat-inactivated bacteria powder of Bifidobacterium lactis BA-C44.

5. The use according to claim 3, characterized in that: The medicine comprises inactivated bacteria, live bacteria powder and / or heat-inactivated bacteria powder of Bifidobacterium lactis BA-C44, and / or other medicines compatible with the inactivated bacteria, live bacteria powder and / or heat-inactivated bacteria powder of Bifidobacterium lactis BA-C44, as well as pharmaceutically acceptable carriers and / or excipients.

6. The use according to claim 2, characterized in that: The relief of ulcerative colitis symptoms includes relief of weight loss, colon shortening, and colon tissue lesions.

7. The use according to claim 2, characterized in that: The relieving of the symptoms of ulcerative colitis includes reducing the spleen index and increasing the thymus index.

8. The use according to claim 2, characterized in that: The symptom relief of ulcerative colitis includes inhibiting the excessive inflammatory markers IL-8, TNF-α and / or IFN-γ produced by the body, and promoting the expression of the anti-inflammatory cytokine IL-10.

9. Use of Bifidobacterium lactis BA-C44 according to claim 1 in the preparation of a product that activates the anti-inflammatory cytokine IL-10 by inhibiting IL-8, TNF-α and / or IFN-γ signaling pathways.

10. The Bifidobacterium lactis BA-C44 according to any one of claims 1 to 9, wherein the strain culture method comprises the following steps: (1) Preparation of MRS medium: Prepare raw materials according to 20 g / L glucose, 10 g / L peptone, 5 g / L yeast extract, 10 g / L beef extract, 1 mL Tween-80, 2 g / L dipotassium hydrogen phosphate, 2 g / L diammonium citrate, 5 g / L sodium acetate, 0.58 g / L magnesium sulfate heptahydrate, and 0.25 g / L manganese sulfate tetrahydrate, mix them evenly, dissolve the obtained mixture in deionized water, and sterilize the obtained solution at a temperature of 121° C. for 20 min to obtain the MRS medium; (2) Cultivation of strains: Live bacterial powder of Bifidobacterium lactis BA-C44 was streaked into the MRS medium of step 1 containing 2% agar, and cultured anaerobically at 37°C for 48 h. A single colony was picked and inoculated into MRS liquid medium and cultured anaerobically at 37°C for 18 h.

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