A selenium-enriched probiotic that affects irinotecan-induced diarrhea and intestinal flora in mice

Abstract

The present invention discloses a selenium-rich probiotic that affects irinotecan-induced diarrhea and intestinal flora in mice, establishes an irinotecan-induced diarrhea mouse model, and administers selenium-rich probiotics by long-term oral gavage to evaluate its effects on irinotecan-induced diarrhea and intestinal flora in mice. The mice in the experimental group were given selenium-rich probiotics by oral gavage every day, and the weight, diarrhea grade, immune index, intestinal flora and ileum tissue structure of the mice were measured. The results show that selenium-rich probiotics can inhibit weight loss and reduced immune function caused by irinotecan; reduce the incidence of diarrhea and the average diarrhea grade in mice, and alleviate irinotecan-induced diarrhea in mice; reduce the content of Clostridium, Escherichia coli and Bacteroidetes associated with β-D-glucuronidase, and increase the content of bifidobacteria in the intestine; alleviate the damage of intestinal mucosa, cells and glands of mice caused by irinotecan.

Description

Technical Field

[0001] The invention belongs to the technical field of microorganisms, and in particular relates to a selenium-enriched probiotic bacteria that affects irinotecan-induced diarrhea and intestinal flora in mice. Background Art

[0002] Irinotecan (CPT-11) is a compound derived from camptothecin and is widely used in the treatment of various tumor diseases, such as non-small cell lung cancer, gastric cancer and rectal cancer. After entering the body, CPT-11 can be rapidly hydrolyzed into the active compound SN-38 in the gastrointestinal tract and liver tissue. SN-38 is metabolized into the inactive metabolite SN-38 glucuronide (SN-38G) during hepatic glucuronidation and then exported to the intestine. However, SN-38G can be hydrolyzed into SN-38 by intestinal bacterial β-D-glucuronidase, resulting in intestinal toxicity. CPT-11 can also cause adverse reactions such as spinal cord suppression toxicity, neutrophil and leukopenia.

[0003] Bifidobacterium is a living intestinal microorganism. As a drug or food supplement, it helps maintain the microbalance of the digestive tract of humans or other hosts, and can absorb trace elements through its own transformation and change physiological and biochemical functions. The trace element selenium (Se) is an essential element for the human body. It forms selenoproteins with proteins to maintain physiological functions, and forms selenoenzymes with 25-30 genetically specific enzymes to maintain catalytic functions. It plays an important role in biochemistry and physiology. The dominant strain of selenium-resistant Bifidobacterium longum was obtained by high-throughput screening. 16SrDNA sequencing and nucleotide sequence BLAST analysis showed that the Bifidobacterium longum DD98 strain was a new strain of Bifidobacterium longum (CGMCC No. 16573).

[0004] Selenium-enriched Bifidobacterium longum DD98 strain is inoculated into RCM modified medium, and after anaerobic culture for 12 hours, sodium selenite is added to the medium, and culture is continued for 24 hours, and Se-DD98 is fermented in a high-selenium environment, and freeze-dried for 48 hours to obtain freeze-dried bacterial powder. The previously disclosed patent (CN108721337A) elaborates on the detailed preparation process of selenium-enriched Bifidobacterium longum and its protective effect on intestinal mucosa.

[0005] Since the adverse reactions of CPT-11 limit its clinical application, the present invention investigates the effects of selenium-enriched Bifidobacterium longum DD98 strain on irinotecan-induced diarrhea and intestinal flora in mice. Summary of the invention

[0006] The present invention aims at the adverse reactions of the current clinical application of CPT-11, and provides a probiotic that affects irinotecan-induced diarrhea and intestinal flora in mice. An irinotecan-induced diarrhea mouse model is established, and selenium-rich probiotics are administered by long-term oral administration, which can inhibit the weight loss and immune function reduction caused by irinotecan; reduce the incidence of diarrhea in mice and the average diarrhea grade, and relieve irinotecan-induced diarrhea in mice; reduce the content of Clostridium, Escherichia coli and Bacteroidetes related to β-D-glucuronidase, and increase the content of Bifidobacterium in the intestine; and relieve the damage of intestinal mucosa, cells and glands of mice caused by irinotecan.

[0007] The specific experimental scheme of the present invention is as follows:

[0008] Mice were divided into normal control group, CPT-11 group, Se-DD98 low-dose group, and Se-DD98 high-dose group. The normal control group and CPT-11 group were gavaged with distilled water, the Se-DD98 low-dose group was gavaged with bacterial powder (live bacteria count 1×108 CFU / kg), and the Se-DD98 high-dose group was gavaged with bacterial powder (live bacteria count 1×109 CFU / kg). Irinotecan diarrhea model was established. From day 0 to day 24, mice in each group were gavaged with sterile water or bacterial solution; on day 18, the normal control group was intraperitoneally injected with sterile saline, and each mouse in the other groups was intraperitoneally injected with 150 mg / kg CPT-11; on days 17 and 24, 6 mice were taken from each group to observe the changes in physiological and biochemical indicators and intestinal flora.

[0009] The selenium-enriched probiotics of the present invention are prepared by inoculating the long Bifidobacterium DD98 strain into the RCM modified culture medium, anaerobic culture for 12 hours, adding sodium selenite to the culture medium, continuing to culture for 24 hours, fermenting to prepare Se-DD98 in a high-selenium environment, and freeze-drying for 48 hours to obtain freeze-dried bacterial powder. The selenium-resistant long Bifidobacterium DD98 strain was obtained by high-throughput screening, and the 16SrDNA sequencing and nucleotide sequence BLAST analysis showed that the long Bifidobacterium DD98 strain was a new long Bifidobacterium (CGMCC No. 16573). The preparation process of selenium-enriched probiotics has been described in detail in the previous public patent (CN108721337A).

[0010] In a first aspect of the present invention, there is provided a use of selenium-enriched Bifidobacterium longum in the preparation of a medicament, wherein the medicament is used for:

[0011] (1) Adjuvant therapy with irinotecan: and / or;

[0012] (2) Alleviate the adverse reactions caused by irinotecan;

[0013] (3) Regulate intestinal flora.

[0014] In another preferred embodiment, the drug is used to alleviate weight loss caused by irinotecan.

[0015] In another preferred embodiment, the drug is used to alleviate the decreased immune function caused by irinotecan.

[0016] In another preferred embodiment, the drug is used to reduce the incidence and average diarrhea grade of mice, and alleviate irinotecan-induced diarrhea in mice.

[0017] In another preferred embodiment, the drug is used to reduce liver aspartate aminotransferase and alanine aminotransferase, and alleviate irinotecan-induced liver toxicity in mice.

[0018] In another preferred embodiment, the intestinal flora includes Clostridium, Escherichia coli, Bacteroides and Bifidobacterium.

[0019] In another preferred embodiment, the drug is used to regulate the intestinal flora of normal mice before and after irinotecan injection.

[0020] In another preferred embodiment, the drug is used to alleviate the damage to the intestinal mucosa, cells and glands of mice caused by irinotecan.

[0021] In another preferred embodiment, the selenium-enriched Bifidobacterium longum is the selenium-enriched Bifidobacterium longum DD98 strain.

[0022] The second aspect of the present invention provides a selenium-enriched probiotic powder, wherein the selenium-enriched probiotic powder is a live bacterial powder of selenium-enriched Bifidobacterium longum DD98 strain.

[0023] In another preferred embodiment, the selenium-enriched Bifidobacterium longum is in the form of a liquid preparation, a powder or a tablet.

[0024] In another preferred example, the selenium content in the selenium-enriched Bifidobacterium longum is 0.349 μg / mg.

[0025] In another preferred example, the viable bacterial count of the selenium-enriched Bifidobacterium longum is 5.2×108 CFU / g.

[0026] The third aspect of the present invention provides a method for preventing and / or treating intestinal disorders caused by irinotecan, the method comprising the steps of: administering a preventive and / or therapeutically effective amount of selenium-enriched Bifidobacterium longum to a subject in need thereof.

[0027] In another preferred embodiment, the subject is a tumor patient.

[0028] In another preferred embodiment, the intestinal flora disorder is the intestinal flora change caused by irinotecan.

[0029] In another preferred embodiment, the dosage of the selenium-enriched Bifidobacterium longum is 1×108-1×1010 CFU / kg, preferably 1×109 CFU / kg.

[0030] In another preferred embodiment, the subject is a human.

[0031] In another preferred embodiment, in the method, a preventive and / or therapeutically effective amount of selenium-enriched Bifidobacterium longum is administered to a subject in need thereof before irinotecan treatment.

[0032] In another preferred embodiment, in the method, a preventive and / or therapeutically effective amount of selenium-enriched probiotics is administered to a subject in need 18 days before irinotecan treatment; preferably, the dose used each time is 1×108 CFU / kg; more preferably, the dose used each time is 1×109 CFU / kg.

[0033] Advantages of the present invention:

[0034] 1. The present invention uses an animal experimental model to explore the effects of long-term administration of selenium-enriched probiotics on the body weight, diarrhea, immune indexes, liver indexes, intestinal flora and ileum structure of normal animals;

[0035] 2. The present invention uses intraperitoneal injection of CPT-11 into mice to explore the effects of selenium-enriched probiotics on the adverse reactions caused by CPT-11, and the adverse reactions include weight changes, diarrhea, reduced immunity, and changes in intestinal flora and ileum structure;

[0036] 3. The present invention provides a selenium-rich probiotic that affects irinotecan-induced diarrhea and intestinal flora in mice, providing new ideas for the clinical application of COT-11. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is the percentage change curve of the original body weight of mice in Example 2 of the present invention.

[0038] Figure 2 This is the effect curve of selenium-enriched probiotics on the incidence of diarrhea in mice in Example 3 of the present invention.

[0039] Figure 3 This is a comparison chart of the effects of selenium-enriched probiotics on the intestinal flora of mice in Example 6 of the present invention (Figure legend: A Clostridium; B Escherichia coli; C Bacteroides; D Bifidobacterium).

[0040] Figure 4 This is a comparison chart of the effects of selenium-enriched probiotics on the histological structure of mouse ileum in Example 7 of the present invention (Figure legend: A normal control group on day 17; B irinotecan group on day 17; C Se-DD98 low-dose group on day 17; D Se-DD98 high-dose group on day 17; E normal control group on day 24; F irinotecan group on day 24; G Se-DD98 low-dose group on day 24; H Se-DD98 high-dose group on day 24). DETAILED DESCRIPTION

[0041] The present invention is further described in detail below with reference to embodiments, but the present invention is not limited to the given examples.

[0042] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation plan and a specific operation process are given, but the protection scope of the present invention is not limited to the following examples.

[0043] Example 1 Preparation of Se-DD98

[0044] The Bifidobacterium longum DD98 strain used in the present invention is amplified by using the bacterial 16S universal primers after extracting the bacterial genomic DNA to obtain the 16SrDNA gene sequence of the bacteria, which is shown in SEQ ID No: 1.

[0045] By using 16SrDNA sequencing and nucleotide sequence BLAST analysis, the strain is not completely identical to the corresponding sequences of all other known long bifidobacteria, but has certain homology. Sugar fermentation characteristics analysis and comparison with Bergey's Bacterial Identification Manual further confirm that the strain belongs to long bifidobacterium, but the result of comparing the 16S rDNA sequence with the standard strain long bifidobacterium JCM 11342 (its 16S rDNA sequence is shown in Genebank No.: LC306854.1) shows that the strain of the present invention is different from the standard strain in sequence. Therefore, it can be seen that the strain of the present invention is a new long bifidobacterium that has not been isolated in the past.

[0046] RCM (modified) medium: 1% beef extract, 0.5% peptone, 0.3% yeast powder, 0.6% glucose, 0.5% sodium chloride, 0.3% anhydrous sodium acetate, 0.05% L-cysteine ​​hydrochloride, and 1.5%~1.8% agar.

[0047] Cultivation method: Bifidobacterium longum DD98 was inoculated into the culture medium for activation for 24 h, then inoculated into the seed culture medium for 12 h, and the seed solution was inoculated into the fermentation medium at 5% (v / v) for 16 h, and then part of the fermentation solution in the fermenter was released, and then feeding (containing sodium selenite) was started and continued to be cultured for 12 h, and finally Se-DD98 was fermented in a high-selenium environment. After the feeding, the Se-DD98 bacterial solution was collected, centrifuged at 14000 r / min for 10 min, and the supernatant was discarded. After centrifugation, the bacteria were washed three times with sterile saline (0.9%) to obtain concentrated Se-DD98. The concentrated Se-DD98 bacterial solution was placed in a freeze dryer, and freeze-dried for 48 h to obtain freeze-dried Se-DD98 bacterial powder, which was sealed and stored at 4°C.

[0048] The detection method of selenium content in Se-DD98 bacterial powder refers to the national standard GB 5009.93-2010 "Determination of selenium in food".

[0049] Determination of viable bacterial count in Se-DD98 bacterial powder: Accurately weigh an appropriate amount of bacterial powder into a 1.5 ml centrifuge tube, add 1.0 ml of sterile saline to the centrifuge tube, vortex until completely dissolved, use gradient dilution method to reach an appropriate dilution, spread on a plate, and culture anaerobically at 37 °C for 48 h. When the colonies are clearly visible and the colonies are of appropriate size, take them out for viable bacterial count.

[0050] The number of viable bacteria (CFU / g) = (the sum of the colony counts on 3 plates) / 3*10*final dilution / weight of bacterial powder.

[0051] Table 1 English abbreviations

[0052]

[0053] Example 2 Changes in mouse body weight

[0054] Mice were randomly divided into 4 groups, 12 in each group, namely normal control group, CPT-11 group, low-dose Se-DD98 group, and high-dose Se-DD98 group. The normal control group and CPT-11 group were gavaged with distilled water, the low-dose Se-DD98 group was gavaged with bacterial powder (live bacteria count 1×108 CFU / kg), and the high-dose Se-DD98 group was gavaged with bacterial powder (live bacteria count 1×109 CFU / kg), 0.2 ml / 10g, once a day. Irinotecan diarrhea model was established. From day 0 to day 24, mice in each group were gavaged with sterile water or bacterial solution; on day 18, the normal control group was intraperitoneally injected with sterile saline, and each mouse in the other groups was intraperitoneally injected with 150 mg / kg CPT-11, with an injection volume of 0.1 ml / 10 g; on days 17 and 24, 6 mice in each group were taken to investigate the changes in physiological and biochemical indicators and intestinal flora. After the experiment started, the condition of the mice was observed at 9:00 am every day, and the weight of mice in each group was measured and recorded.

[0055] Table 2 Experimental groups and drug administration

[0056]

[0057] Table 3 Percentage of original body weight of mice from 18 days to 24 days

[0058]

[0059] Table Notes: Compared with the normal group, *p <0.05, **p <0.01; compared with the irinotecan group, △ p < 0.05,△△ p <0.01; compared with low dose, # p < 0.05, ## p < 0.01.

[0060] The above research results show that:

[0061] 1. Figure 1 The results showed that the percentage of original body weight of mice in the irinotecan group, Se-DD98 low-dose group, and high-dose group all showed a trend of first decreasing and then rising after the injection of irinotecan on the 18th day;

[0062] 2. The results in Table 3 showed that after the injection of irinotecan, the original body weight percentages of the irinotecan group, the low-dose Se-DD98 group and the high-dose Se-DD98 group were significantly reduced (p < 0.05 or p < 0.01). However, compared with the irinotecan group, the original body weight percentages of the low-dose Se-DD98 group and the high-dose Se-DD98 group were significantly reduced in the early stage (p < 0.05 or p < 0.01), and significantly increased in the later stage (p < 0.05 or p < 0.01), and the original body weight percentage of the high-dose Se-DD98 group was significantly higher than that of the low-dose Se-DD98 group (p < 0.05 or p < 0.01);

[0063] 3. The results showed that irinotecan caused weight loss in mice, while long-term preventive administration of Se-DD98 powder could inhibit the weight loss caused by irinotecan in a dose-dependent manner.

[0064] Example 3 Evaluation of the incidence and grade of diarrhea in mice

[0065] 24 h after irinotecan injection, the diarrhea of ​​mice in each group was observed and scored at 48, 72, 96, 120 and 144 h.

[0066] Table 4 Evaluation criteria for mouse diarrhea

[0067]

[0068] Table 5 Effect of Se-DD98 on the average diarrhea grade of mice with irinotecan-induced diarrhea

[0069]

[0070] Table Notes: Compared with the normal group, *p<0.05, **p<0.01; compared with the irinotecan group, △ p<0.05, △△ p<0.01.

[0071] in conclusion:

[0072] 1. Figure 2The results showed that the incidence of diarrhea in the irinotecan group and the low-dose Se-DD98 group changed over time, showing a trend of gradually increasing first, decreasing later, and then remaining unchanged. The high-dose Se-DD98 group remained unchanged after decreasing for 48 hours, but the incidence of diarrhea in the high-dose Se-DD98 and low-dose Se-DD98 groups was lower than that in the irinotecan group;

[0073] 2. The results in Table 5 show that the average diarrhea grades of the irinotecan group and the high- and low-dose Se-DD98 groups also changed over time, increasing first and then decreasing. The average diarrhea grades of the irinotecan group at each time point were significantly higher than those of the normal control group (p < 0.05 or p < 0.01). The average diarrhea grades of the Se-DD98 low-dose group at the last time point and the Se-DD98 high-dose group at each time point in the middle and late stages were significantly lower than those of the irinotecan group (p < 0.05 or p < 0.01);

[0074] 3. The results showed that irinotecan caused different degrees of diarrhea in mice, and the average diarrhea grade first increased and then decreased. Preventive administration of Se-DD98 powder could reduce the incidence and average diarrhea grade of mice, and alleviate the persistent diarrhea caused by irinotecan in mice.

[0075] Case 4 Determination of mouse spleen index and peripheral blood routine indicators

[0076] On the 17th and 24th days, 6 mice were randomly selected from each group and weighed. Blood was collected into anticoagulant tubes containing heparin by the inner canthus method and mixed by inversion for routine peripheral blood testing. Mice were killed by cervical dislocation and operated on ice. The spleen was removed and weighed, and the spleen index was calculated according to the formula organ index = organ mass (mg) / body mass (g).

[0077] Table 6 Effects of Se-DD98 on immune parameters in mice with irinotecan-induced diarrhea

[0078]

[0079] Table Notes: Compared with the normal group, *p<0.05, **p<0.01; compared with the irinotecan group, △ p<0.05, △△ p<0.01.

[0080] in conclusion:

[0081] 1. The experimental data showed that on the 17th day (before irinotecan injection), there was no significant difference in the spleen index, white blood cell index, lymphocyte index and neutrophil index of each group of mice. On the 24th day (after irinotecan injection), compared with the normal control group, the spleen index and white blood cell count of the irinotecan group were significantly reduced (p <0.01). Compared with the irinotecan group, the spleen index and neutrophil index of the low-dose Se-DD98 group were significantly increased (p <0.05), and the spleen index, white blood cell index and neutrophil count of the high-dose Se-DD98 group were significantly increased (p <0.05 or p <0.01);

[0082] 2. The results showed that long-term preventive administration of Se-DD98 powder before irinotecan injection had no effect on the immune function of mice. Irinotecan injection caused a decrease in the immune function of mice, while preventive administration of Se-DD98 powder could improve the immune function of mice. It can be inferred that Se-DD98 powder can alleviate the decrease in immunity caused by irinotecan and enhance the immune function.

[0083] Example 5 Determination of Mouse Liver Index and ALT and AST Indexes

[0084] On the 17th and 24th days, 6 mice were randomly selected from each group and weighed. Blood was collected by the inner canthus method into a centrifuge tube containing heparin or not. After standing for 1 hour, the blood was centrifuged at 6000 rpm for 10 minutes, and the supernatant was obtained to obtain serum. The serum was tested on an automatic biochemical analyzer according to the ALT and AST kits. The mice were killed by cervical dislocation, and the operation was carried out on ice. The liver was removed and weighed, and the spleen index was calculated according to the formula organ index = organ mass (mg) / body mass (g).

[0085] Table 7 Effects of Se-DD98 on liver parameters in mice with irinotecan-induced diarrhea

[0086]

[0087] Table Notes: Compared with the normal group, *p<0.05, **p<0.01; compared with the irinotecan group, △ p<0.05, △△ p<0.01; compared with the low-dose Se-DD98 group, # p<0.05, ## p<0.01.

[0088] From the above results, we can know that:

[0089] 1. The experimental data showed that on the 17th day (before irinotecan injection), the liver index of the Se-DD98 high-dose group was significantly reduced compared with the normal control group (p < 0.01). Compared with the irinotecan group, the liver index of the Se-DD98 low-dose group and the high-dose group was significantly reduced (p < 0.01). There was no significant difference in the leukocyte index, lymphocyte index and neutrophil index of the mice in each group. On the 24th day (after irinotecan injection), compared with the normal control group, the liver index of the irinotecan group was significantly reduced (p < 0.01), the ALT of the Se-DD98 high-dose group was significantly reduced (p < 0.01), and the AST of the irinotecan group, the Se-DD98 low-dose group and the high-dose group was significantly reduced (p < 0.01). Compared with the irinotecan group, the AST of the Se-DD98 low-dose group and the high-dose group was significantly reduced (p < 0.01). Compared with the Se-DD98 low-dose group, the Se-DD98 high-dose group was significantly reduced (p < 0.01);

[0090] 2. The results showed that long-term preventive administration of Se-DD98 powder before irinotecan injection had an effect on liver index. Irinotecan injection caused a decrease in the liver index and AST of mice, while preventive administration of Se-DD98 powder could improve the liver function of mice. It can be inferred that Se-DD98 powder can alleviate the decrease in liver indexes caused by irinotecan and enhance liver function.

[0091] Example 6 Determination of relative abundance of intestinal microorganisms in mice

[0092] Mice were killed by cervical dislocation, and the operation was performed on ice. 0.2 g of cecal contents were taken out and placed in a clean EP tube and stored in a -80°C refrigerator. Fecal total DNA was extracted using a fecal gene DNA extraction kit, and the DNA concentration was determined by an ultra-micro UV spectrophotometer and diluted. Fluorescence quantitative qPCR was used to determine the relative abundance of Bacteroides, Bifidobacterium longum, Lactobacillus, Clostridium and Escherichia coli, and the CT detection limit was 40 cycles.

[0093] Table 8 qPCR primer design

[0094]

[0095] Table 9 qPCR reaction system

[0096]

[0097] Table 10 qPCR reaction conditions

[0098]

[0099] in conclusion:

[0100] 1. Bacteroidetes, Clostridium and Escherichia coli can enhance the activity of β-D-glucuronidase, promoting the conversion of inactive compound SN-38G in the intestine into active compound SN-38, thereby exacerbating diarrhea in mice. Kulkarni's research group showed

[24] that Bifidobacterium longum in the diet can affect the metabolic activity of certain intestinal microbial flora related to β-D-glucuronidase;

[0101] 2. Figure 3 The results showed that on the 17th day (before irinotecan injection), compared with the normal control group, the relative abundance of Clostridium, Escherichia coli and Bacteroides in the Se-DD98 group was significantly reduced (p < 0.05 or p < 0.01); while the relative abundance of Bifidobacterium increased significantly (p < 0.01). Compared with the irinotecan group, the relative abundance of Escherichia coli and Bacteroides in the Se-DD98 group was significantly reduced (p < 0.01); the relative abundance of Bifidobacterium increased significantly (p < 0.01). The decrease in Bacteroides and the increase in Bifidobacterium in the low-dose and high-dose Se-DD98 groups were dose-dependent;

[0102] 3. On the 24th day (after irinotecan injection), compared with the normal control group, the irinotecan group had a significant increase in Clostridium and Bacteroides (p < 0.01), and a significant decrease in Escherichia coli and Bifidobacterium (p < 0.01); the Se-DD98 low-dose group and high-dose group had a significant decrease in Escherichia coli and Bacteroides (p < 0.01), while a significant increase in Clostridium and Bifidobacterium (p < 0.01). Compared with the irinotecan group, the relative abundance of Clostridium, Escherichia coli, and Bacteroides in the Se-DD98 low-dose group and high-dose group was significantly reduced (p < 0.01), while a significant increase in Bifidobacterium (p < 0.01). The decrease in Bacteroidetes and the increase in Bifidobacterium in the Se-DD98 low-dose group and high-dose group were dose-dependent ( Figure 3 );

[0103] 4. The above results show that irinotecan injection leads to an increase in the relative abundance of Clostridium and Bacteroides associated with β-D-glucuronidase in the intestines of mice. Long-term preventive administration of Se-DD98 powder can reduce the relative abundance of Clostridium, Escherichia coli and Bacteroides in the intestines of mice, and increase the relative abundance of Bifidobacterium longum. It can be inferred that Se-DD98 powder can reduce the content of intestinal bacteria associated with β-D-glucuronidase and increase the content of Bifidobacterium.

[0104] Example 7 Hematoxylin and eosin (HE) staining of mouse ileum tissue

[0105] Mice were killed by cervical dislocation, and ileal tissue was obtained 5 cm from the ileocecal valve, rinsed with 0.9% saline, and fixed in formalin for 24 h. Paraffin tissue sections were dewaxed to water and washed 3 times, 2 minutes each time; the sections were immersed in hematoxylin solution for 5 minutes, then washed with water for 1 minute; differentiated with hydrochloric acid and alcohol for 30 seconds, then rinsed with running water for 5 minutes; immersed in eosin staining solution for 3 minutes, then rinsed with running water for 30 seconds; dehydrated with ethanol step by step, and finally transparentized with xylene, sealed with neutral gum, and observed under an optical microscope.

[0106] Result analysis:

[0107] 1. Figure 4 The results showed that on the 17th day (before irinotecan injection), the intestinal wall structures of all layers of the small intestine of mice in each group were intact, no ulcers were formed, the size, morphology and distribution of the glands were normal, and no inflammatory cell infiltration was observed in the intestinal wall. On the 24th day (after irinotecan injection), compared with the normal control group, the small intestinal mucosa of the irinotecan group became thinner, the mucosal epithelial cells degenerated, necrotic and fell off, a large number of inflammatory cells infiltrated, the glands atrophied, and the intestinal glands decreased. Compared with the irinotecan group, some mucosal epithelial cells in the low-dose and high-dose Se-DD98 groups degenerated, necrotic and fell off, and a small number of inflammatory cells infiltrated;

[0108] 2. The results showed that irinotecan can cause thinning of the ileal mucosa, degeneration of mucosal cells, and atrophy of glands in mice. Long-term preventive administration of Se-DD98 powder had no effect on the ileal mucosa, cells, and glands of normal mice, but could alleviate the damage to the intestinal mucosa, cells, and glands caused by irinotecan. Sequence Listing <110> Jiangsu Dexi Biotechnology Co., Ltd.; Shanghai Jiao Tong University <120> A selenium-enriched probiotic that affects irinotecan-induced diarrhea and intestinal flora in mice <130> 2019 <160> 1 <170> SIPOSequenceListing 1.0 <210> 2 <211> 1227 <212> DNA <213> Bifidobacterium Longum DD98 <400> 2 cggagtctac ttagacggct catcccacaa ggggttaggc caccggcttc gggtgctgcc 60 cactttcatg acttgacggg cggtgtgtac aaggcccggg aacgcattca ccgcgacgtt 120 gctgattcgc gattactagc gactccgcct tcacgcagtc gagttgcaga ctgcgatccg 180 aactgagacc ggttttcagg gatccgctcc gcgtcgccgc gtcgcatccc gttgtaccgg 240 ccattgtagc atgcgtgaag ccctggacgt aaggggcatg atgatctgac gtcatcccca 300 ccttcctccg agttaacccc ggcggtcccc cgtgagttcc cggcataatc cgctggcaac 360 acggggcgag ggttgcgctc gttgcgggac ttaacccaac atctcacgac acgagctgac 420 gacgaccatg caccacctgt gaacccgccc cgaagggaag ccgtatctct acgaccgtcg 480 ggaacatgtc aagcccaggt aaggttcttc gcgttgcatc gaattaatcc gcatgctccg 540 ccgcttgtgc gggcccccgt caatttcttt gagttttagc cttgcggccg tactccccag 600 gcgggatgct taacgcgtta gctccgacac ggaacccgtg gaacgggccc cacatccagc 660 atccaccgtt tacggcgtgg actaccaggg tatctaatcc tgttcgctcc ccacgctttc 720 gctcctcagc gtcagtaacg gcccagagac ctgccttcgc cattggtgtt cttcccgata 780 tctacacatt ccaccgttac accgggaatt ccagtctccc ctaccgcact caagcccgcc 840 cgtacccggc gcggatccac cgttaagcga tggactttca caccggacgc gacgaaaccg 900 cctacgagcc ctttacgcc aataattccc ggataacgct tgcaccctac gtattaccgc 960 ggctgctggc acgtagttag ccggtgctta ttcaacgggt aaactcactc tcgcttgctc 1020 ccgataaaag aggttacaac ccgaaggcct ccatccctca cgcggcgtcg ctgcatcagg 1080 cttgcgccca ttgtgcaata ttccccact gctgcctccc gtagagtctg gacgtattcc 1140 tcagtccatg tgacatcgcc cctcttcagt cggctacgtt cgaagcctac gggtgggccg 1200 tagccggcgt tcaagcctgg tatatag 1227

Claims

1. Use of the Selenium-enriched Bifidobacterium longum DD98 strain in the preparation of a drug for alleviating irinotecan-induced diarrhea.

2. The use according to claim 1, characterized in that A preventive effective amount of the selenium-enriched Bifidobacterium longum DD98 strain is administered to a subject in need thereof 18 days prior to irinotecan treatment.

3. The use according to claim 1, characterized in that The selenium content of the selenium-enriched Bifidobacterium longum DD98 strain is 0.349 μg / mg.

4. The use according to claim 1, characterized in that The medicine is a live selenium-enriched Bifidobacterium longum DD98 strain preparation.

5. The use according to claim 1, characterized in that The viable count of selenium-enriched Bifidobacterium longum DD98 in the drug is 5.2×10 8 CFU / g.

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