CN117838706A - Application of obeticholic acid in the preparation of drugs for preventing and/or treating radiation-induced intestinal injury - Google Patents

Abstract

The present invention relates to the preparation of drugs for preventing and/or treating radiation-induced intestinal injury, and specifically to the use of obeticholic acid in the preparation of drugs for preventing and/or treating radiation-induced intestinal injury. In order to solve the deficiency of the prior art in lacking radiation protection drugs for radiation-induced intestinal injury, the present invention provides the use of obeticholic acid in the preparation of drugs for preventing radiation-induced intestinal injury, and the use of obeticholic acid in the preparation of drugs for treating radiation-induced intestinal injury. Furthermore, obeticholic acid has good effects in the preparation of drugs for reducing apoptosis of intestinal epithelial cells after radiation, promoting proliferation of intestinal crypts after radiation, and promoting proliferation of intestinal villus cells after radiation.

Description

Application of obeticholic acid in the preparation of drugs for preventing and/or treating radiation-induced intestinal injury

Technical Field

The present invention relates to the preparation of a drug for preventing and/or treating radiation-induced intestinal injury, and in particular to the use of obeticholic acid in the preparation of a drug for preventing and/or treating radiation-induced intestinal injury.

Background technique

When patients with pelvic and abdominal malignancies and peritoneal malignancies undergo radiotherapy, the healthy intestine is inevitably exposed to ionizing radiation. Since the small intestine is the main sensitive site for abdominal radiotherapy, it is easy to cause intestinal complications and form radiation-induced intestinal injury, also known as radiation enteritis. Intestinal damage caused by strong radiation can cause systemic inflammatory response syndrome, leading to rapid loss of mucosal epithelium, bleeding, infection, sepsis and even death. Although the intestine begins the regeneration process after radiation damage, there is still a large loss of LGR5+ intestinal stem cells and proliferating progenitor cells. Ionizing radiation can damage basal epithelial cells, hinder their renewal, and lead to histologically detectable intestinal epithelial cell changes, such as reduced height and number of intestinal villi, inflammation, intestinal wall edema and fibrin deposition.

Clinical data show that about 50% of cancer patients receive radiotherapy, and up to 70% of them experience varying degrees of gastrointestinal symptoms after receiving abdominal or pelvic radiotherapy, which seriously affects the follow-up treatment plan of cancer patients and the quality of life of survivors. At present, there is still a lack of effective treatment for radiation-induced intestinal injury, which is limited to symptomatic supportive treatment such as anti-infection, nutritional support, protection of gastrointestinal mucosa, antidiarrhea, regulation of intestinal flora, and surgical resection of the diseased intestinal segment. Therefore, there is an urgent need to develop more radiation protection drugs to prevent and/or treat radiation-induced intestinal injury.

Obticholic acid (OCA, also known as 6-ECDCA or INT-747) is an effective farnesoid X receptor (FXR) agonist and a semi-synthetic derivative of human primary bile acid chenodeoxycholic acid (CDCA). Clinical studies have found that OCA is well tolerated, helps improve patient symptoms, delay disease progression, and improve patient survival. FXR is a nuclear receptor mainly expressed in the liver and small intestine, and is a key regulator of bile acid, inflammation, fibrosis, and metabolic pathways. FXR also has a protective effect on the liver and is involved in pathological and physiological processes such as liver detoxification, liver regeneration, and prevention of liver fibrosis. There is no literature reporting the use of OCA in the treatment of radiation-induced intestinal injury.

Summary of the invention

The purpose of the present invention is to solve the deficiency of the prior art in lacking radiation protection drugs for radiation intestinal injury, and to provide a use of obeticholic acid in the preparation of drugs for preventing and/or treating radiation intestinal injury.

To achieve the above objectives, the technical solutions provided by the present invention are as follows:

The present invention provides an application of obeticholic acid in preparing a medicine for preventing radiation-induced intestinal damage.

And the use of obeticholic acid in the preparation of drugs for reducing intestinal epithelial cell apoptosis after radiation.

And the use of obeticholic acid in the preparation of drugs for treating radiation-induced intestinal injury.

And the use of obeticholic acid in the preparation of drugs for promoting proliferation of intestinal crypts after radiation.

And the application of obeticholic acid in the preparation of drugs for promoting the proliferation of intestinal villus cells after radiation.

And the use of obeticholic acid in the preparation of drugs for treating post-radiation intestinal inflammation.

And the application of obeticholic acid in the preparation of drugs for repairing intestinal mucosal damage after radiation.

Beneficial effects of the present invention:

This application uses radiation-induced intestinal injury mice as the research object, and for the first time applies OCA to the study of radiation-induced intestinal injury. The results show that:

OCA can well protect the intestinal villus structure, crypt number and colon length after irradiation and reduce radiation-induced intestinal damage;

OCA can effectively improve intestinal damage caused by radiation and reduce the expression of inflammatory cytokines;

OCA can effectively activate FXR and promote its expression in radiation-induced intestinal injury.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows the effect of OCA supplementation on radiation-induced intestinal injury in mice induced by X-ray irradiation; A is the percentage of the body weight of the four groups of mice relative to the body weight before the experiment; B is the quantification of the colon length of the four groups of mice; C is the gross morphology of the colon of the four groups of mice; D is a representative image of HE staining of the small intestine tissue of the four groups of mice, Scale bar = 50μm; E is the quantification of the villus length in the small intestine tissue section; F is the quantification of the number of small intestinal crypts. Data are expressed as Mean±SD, n=10, *: p<0.05, **: p<0.01, ***: p<0.001, ****: p<0.0001.

Figure 2 shows the effect of OCA on reducing radiation-induced apoptosis of mouse small intestinal epithelial cells; A is a microscope view of TUNEL staining analysis of small intestinal cells, Scale bar = 100 μm (upper); Scale bar = 20 μm (lower); B is the number of TUNEL-positive cells in each field of view. Data are expressed as Mean ± SD, n = 4, **: p < 0.01, ****: p < 0.0001.

Figure 3 shows the proliferation of intestinal crypt cells in mice with radiation-induced intestinal injury after OCA intervention; A is a representative image of immunohistochemical staining of PCNA and Ki-67 in mouse small intestinal tissue, Scale bar = 100 μm; B is quantitative analysis of immunohistochemical staining of PCNA-positive cells; C is quantitative analysis of immunohistochemical staining of Ki-67-positive cells. Data are expressed as Mean ± SD, n = 5, **p < 0.01, ***p < 0.001.

Figure 4 shows the effect of OCA on inflammatory factors in the small intestine tissue of mice with radiation-induced intestinal injury; A is the expression of IL-1β in the small intestine tissue; B is the expression of TNF-α in the small intestine tissue; C is the expression of IL-6 in the small intestine tissue. Data are expressed as Mean±SD, n=8, *p<0.05, **p<0.01, ***p<0.001.

Figure 5 shows the effect of OCA on the expression of ZO-1 and Occludin in the small intestine of mice with radiation-induced intestinal injury; A is the expression of ZO-1 in the small intestine; B is the expression of Occludin in the small intestine. Data are expressed as Mean±SD, n=8, *p<0.05, **p<0.01.

Figure 6 shows the effect of OCA on FXR expression in mice with radiation-induced intestinal injury; A is a representative image of immunohistochemical staining of FXR in mouse small intestinal tissue, Scale bar = 100 μm; B is a quantitative analysis of immunohistochemical staining of FXR-positive cells in mouse small intestinal tissue; C is qRT-PCR detection of FXR mRNA expression level in mouse small intestinal crypt cells; D is Western blot detection of FXR mRNA expression level in mouse small intestinal crypt cells; E is a quantitative analysis of FXR expression in mouse small intestinal crypt cells. Data are expressed as Mean ± SD, n = 5, *p < 0.05, **p < 0.01, ***p < 0.001.

Detailed ways

The present invention discloses an application of obeticholic acid in the preparation of a drug for preventing and/or treating radiation-induced intestinal injury. Mice with radiation-induced intestinal injury are used as research subjects to explore the application of obeticholic acid in preventing and/or treating radiation-induced intestinal injury.

Unless otherwise specified, the experimental methods used in the examples are all conventional methods; the materials, reagents, etc. used, unless otherwise specified, can be obtained from commercial channels.

In the present embodiment, healthy adult male C57BL/6J mice aged 6 to 8 weeks (20 to 22 g) were used. Under a 12-hour dark/light cycle, mice had free access to water and food, were raised under a normal light and dark cycle, and the bedding was changed regularly to ensure a clean feeding environment. Subsequent experiments were performed after one week of adaptive feeding. In this embodiment, X-rays were used for radiation, and the experimental results are also applicable to radiation intestinal damage caused by gamma rays or other rays.

1. Experimental Methods

(I) Choice of dosage and method of administration

The model of radiation intestinal injury was established by 12Gy X-ray irradiation in the abdomen of mice, and two dosing groups were designed, with the doses of 2.5mg/kg and 5mg/kg, respectively. The effects of OCA administration on radiation intestinal injury mice were evaluated in terms of the number of PCNA and Ki67 positive cells, the number of crypts, and the height of small intestinal villi.

(II) Experimental Animal Grouping

Forty SPF C57BL/6J male mice were randomly divided into 4 groups: normal control group, irradiation control group, OCA administration group (2.5 mg/kg), and OCA administration group (5 mg/kg). The number of mice in each group was n=10.

(III) Method of administration

The mice in the OCA administration group were irradiated once, and the drug was administered 2 hours before irradiation, and continued to be administered for 5 consecutive days after irradiation, once a day. The mice in the irradiation control group were irradiated once, and a volume concentration of 0.5% sodium carboxymethyl cellulose was administered according to the above time nodes. The two OCA administration groups were administered at a dose of 2.5 mg/kg per day and 5 mg/kg per day, respectively. The dose was converted according to the weight of the mice every day, and the dosage per gram of mouse was 10 μL. The irradiation control group was given an equal volume of 0.5% sodium carboxymethyl cellulose, and the normal control group was raised normally.

4. Drug pretreatment

Dosage configuration: OCA is in powder form. According to the weight and number of mice, the corresponding amount of OCA powder is weighed and placed in a test tube with a lid. The OCA powder is dissolved with 0.5% sodium carboxymethyl cellulose. During the dissolution process, a vortex oscillator and ultrasound are used to assist the dissolution.

(V) Construction of a mouse model of radiation-induced intestinal injury

The X-ray device was a Rad Source RS2000 series X-ray biological irradiator, with an operating voltage of 160 kV, an operating current of 25 mA, and a dose rate of 1 Gy/min (monitored in real time by a radiation dosimeter). The abdomen of mice in the control group, the OCA administration group (2.5 mg/kg), and the OCA administration group (5 mg/kg) were irradiated with an X-ray device, and the irradiation range was from the sternum to the pubic symphysis of the mice, and the rest of the body was shielded with a 5 cm thick lead block. The X-ray was irradiated at 1 Gy/min, and the total irradiation dose was 12 Gy. Samples were collected on the 5th day after irradiation and subsequent experiments were performed.

(VI) Sample preparation

On the 5th day after irradiation, 10 mice were selected from each of the normal control group, irradiation control group, and OCA administration group (2.5 mg/kg and 5 mg/kg), and the small intestinal tissues of the mice were taken, fixed with 4% paraformaldehyde, and HE staining was performed. All detection reagents used commercial kits. The small intestinal tissues of all mice were processed in sequence through steps (VII) to (XI) to obtain the corresponding results.

(VII) HE staining

(1) Place the radiation-damaged colon mucosal tissue slices in a 60°C oven for 2 h;

(2) Dewaxing and hydration: Place tissue sections in the following reagents in sequence: biological clearing agent I for 10 min, biological clearing agent II for 10 min, 100% alcohol for 5 min, 90% alcohol for 2 min, 80% alcohol for 2 min, 70% alcohol for 2 min, and ultrapure water for 2 min;

(3) The tissue sections were stained with hematoxylin for 5 min and rinsed with running water for 2 min;

(4) Differentiate the tissue sections with hydrochloric acid alcohol for a few seconds and rinse with running water for 2 minutes;

(5) The tissue sections were stained with eosin for 2 min and washed with distilled water for 1-2 s;

(6) Place tissue sections in the following reagents in sequence: 70% alcohol for 1 min, 95% alcohol for 2 min, 100% alcohol for 2 min, biological clearing agent I for 5 min, and biological clearing agent II for 5 min;

(7) Seal the tissue sections with neutral gum and take photos under a microscope.

(VIII) TUNEL staining

The intestinal sections were stained using a TUNEL kit (Roche) according to the instructions. The results were observed using a confocal microscope, and statistical analysis of intestinal cell apoptosis was performed.

IX. Immunohistochemical staining

(1) Dewaxing and rehydrating the tissue sections obtained in step (VIII) and performing microwave antigen repair using sodium citrate antigen repair solution, first at medium-high heat for 5 minutes, then slowly placing the sections in the microwave at high heat for 5 minutes, and then at medium-low heat for 10 minutes;

(2) Rinse the tissue sections with PBS for 3 min × 3 times, add endogenous peroxidase blocker, incubate at room temperature for 10 min; then rinse with PBS for 5 min × 3 times.

(3) Antibody incubation: Add the prepared antibody dropwise onto the tissue section and incubate at 4°C for 10-12 h;

(4) After incubation, the tissue sections were placed at room temperature for 15 min and rinsed with PBS for 5 min × 3 times;

(5) Incubation with secondary antibody: Add reagent secondary antibody and place in a wet box, incubate at room temperature for 30 min;

(6) DAB staining was performed on the tissue sections, and the reaction was observed under a microscope and terminated;

(7) Hematoxylin counterstaining: The tissue sections were stained with hematoxylin for 5 min, rinsed with running water for 1 min, differentiated with hydrochloric acid and alcohol for a few seconds, and rinsed with running water for 2 min;

(8) Place tissue sections in 70% alcohol for 1 min, 95% alcohol for 2 min, 100% alcohol for 2 min, biological clearing agent I for 5 min, and biological clearing agent II for 5 min, respectively, seal the sections with neutral gum, and take photos under a microscope.

(10) Real-time quantitative PCR (qRT-PCR)

①Total RNA extraction

(1) Extract mouse crypt cells, add 1 ml of TRIzol to the crypt cells, and let stand for 5 min;

(2) Add 200 μL of chloroform, shake vigorously for 15 seconds, let stand for 3 minutes, and centrifuge at 4°C and 12,000 rpm for 15 minutes;

(3) Gently aspirate the upper aqueous phase;

(4) Add 500 μL of isopropanol to the aqueous phase and incubate at room temperature for 10 min;

(5) Centrifugation at 4°C and 12,000 rpm for 10 min;

(6) discarding the waste liquid and adding 75% ethanol to wash the precipitate;

(7) Centrifuge at 7500 rpm for 5 min to remove residual liquid;

(8) After drying for 5 min, add enzyme-free water to obtain total RNA and measure its concentration;

(9) The RNA concentration and purity were determined using NanoDrop 2000. The RNA samples were diluted to the same concentration and reverse transcribed. The resulting cDNA was stored in a −20°C refrigerator.

② RNA reverse transcription

A. Prepare the reverse transcription reaction system according to the table below. Perform the preparation process on ice.

Composition Usage amount 5×All-in-One RT MasterMix 4μL Total RNA 2μL RNase-Free ddH ₂ O 14μL

B. The reaction system was incubated at 25° for 10 min, 42° for 15 min, and 85° for 5 min. The cDNA was stored in a -20°C refrigerator.

③ Prepare PCR reaction solution according to the table below

Among them, the forward primer and reverse primer are shown in the following table:

Primer name Sequence (5'-3') Mouse-IL-1β-F CTCGCAGCAGCACATCAACAAG Mouse-IL-1β-R CCACGGGAAAGACACAGGTAGC Mouse-TNF-α-F ACGCTCTTCTGTCTACTGAACTTCG Mouse-TNF-α-R TGGTTTGTGAGTGTGAGGGTCTG Mouse-IL-6-F TTCTTGGGACTGATGCTGGTGAC Mouse-IL-6-R GTGGTATCCTCTGTGAAGTCTCCTC Mouse-ZO-1-F AGCAGTGGAAGAAGTTACAGTTGAG Mouse-ZO-1-R TAGGCAGAGCACCATCAGAAGG Mouse-Occludin-F TGGCTATGGCGGATATACAGACC Mouse-Occludin-R CTAAGGAAGCGATGAAGCAGAAGG Mouse-FXR-F GCAACCAGTCATGTACAGATTC Mouse-FXR-R TTATTGAAAATCTCCGCCGAAC Mouse-GAPDH-F TGTTCCTACCCCCAATGTGT Mouse-GAPDH-R TGTGAGGGAGATGCTCAGTG

④Set the PCR reaction program according to the table below

⑤ Cycle threshold was used to quantify the mRNA levels of the normal control group, irradiation control group, OCA administration group (2.5 mg/kg) and OCA administration group (5 mg/kg). GAPDH was used as the internal reference gene, and the 2- ^△△CT method was used to compare the differences between the control group and the experimental group.

(XI) Protein immunoblotting

(1) Small intestinal crypt cell protein extraction and BCA protein quantification

First, add corresponding proportions of protease inhibitors, phosphatase inhibitors and PMSF to RIPA lysis buffer; place on ice for lysis for 30 minutes, and vortex and oscillate every 5 minutes to mix; centrifuge at 4°C, 12000rpm for 15 minutes; gently aspirate the supernatant and use the BCA quantitative method; add 5× Loading Buffer to the supernatant, heat in a metal bath at 100°C for 10 minutes to denature the protein, and obtain the protein sample, which is stored in a -80°C refrigerator for subsequent experiments.

(2) SDS-PAGE electrophoresis: SDS-polyacrylamide gel was prepared according to the molecular weight of the protein, and the sample load was 30 μg. The electrophoresis was first performed at a constant voltage of 80 V. After the protein migrated to the separation gel (about 30 min), the electrophoresis was continued at a constant voltage of 120 V.

(3) Transfer: Pre-activate the 0.22 μm PVDF membrane with methanol for 15 s, and transfer the membrane at a constant current of 200 mA for 120 min. The transfer time is determined according to the specific molecular weight.

(4) Blocking: 5% skim milk powder, block for 2 h at room temperature;

(5) Primary antibody incubation: Incubate with primary antibody at 4°C overnight;

(6) Wash the membrane with TBST for 5 min × 3 times;

(7) Secondary antibody incubation: dilute the corresponding species secondary antibody at 1:5000 and incubate at room temperature for 2 h;

(8) Wash the membrane for 5 min × 3 times;

(9) The HRP-ECL chemiluminescence method was used to analyze the bands.

2. Statistical Analysis

All data in experimental analysis were generated using GraphPad Prism 9.2 software (San Diego, CA, USA). Unpaired t-test or one-way ANOVA was used, and all values were expressed as Mean ± SD, where p < 0.05 was considered statistically significant.

3. Experimental Results

(I) OCA supplementation can alleviate X-ray-induced radiation intestinal damage in mice

To explore whether OCA has a protective effect on radiation-induced intestinal injury, C57BL/6J mice were irradiated with 12Gy of X-rays, and different doses of OCA (2.5mg/kg or 5mg/kg) were given 1 hour before irradiation for 5 consecutive days. The mice irradiated with 12Gy of X-rays were radiation-induced intestinal injury mice. The results are shown in Figure 1. As can be seen from Figure 1A, OCA promoted the weight growth of irradiated mice, and as can be seen from Figure 1B and C, OCA significantly increased the length of the mouse colon. As can be seen from Figure 1D, E and F, OCA significantly increased the number of crypts and the length of intestinal villi. The results show that supplementation with OCA can reduce radiation-induced intestinal injury in mice.

(II) OCA can alleviate radiation-induced apoptosis of intestinal epithelial cells in mice

In order to study the effect of OCA on apoptosis of mouse small intestinal epithelial cells, we used the TUNEL method to detect the changes in apoptotic cells. The results are shown in Figure 2. Compared with the control group, there were more apoptotic cells in mice after abdominal irradiation exposure, and OCA significantly reduced the number of apoptotic cells. Therefore, OCA can alleviate the apoptosis of mouse small intestinal epithelial cells induced by high-dose radiation.

(III) OCA promotes the proliferation of small intestinal crypt cells in mice with radiation-induced intestinal injury

To explore whether OCA has a protective effect on the proliferation of crypt cells in mice with radiation-induced intestinal injury, C57BL/6J mice were irradiated with 12Gy of X-rays, and different doses of OCA were given 1 hour before irradiation for 5 consecutive days. The expression levels of PCNA and Ki-67 in the small intestinal tissues of mice with radiation-induced intestinal injury were detected by immunohistochemistry. As shown in Figure 3, radiation significantly reduced the expression levels of PCNA and Ki-67 in the crypt cells of the small intestine of mice, while OCA promoted the expression of PCNA and Ki-67 in the crypt cells of the small intestine of mice. This suggests that OCA can promote the proliferation of crypt cells in the small intestine of mice with radiation-induced intestinal injury.

(IV) OCA reduces the expression of inflammatory factors in the small intestine of mice with radiation-induced intestinal injury

To detect whether OCA has an anti-inflammatory effect in mice with radiation-induced intestinal injury, the expression levels of IL-1β, TNF-α, and IL-6 in small intestinal tissue were detected by qRT-PCR. As shown in Figure 4, the expression levels of IL-1β, TNF-α, and IL-6 were upregulated after irradiation, and OCA treatment significantly reduced the expression of these three inflammatory cytokines in small intestinal tissue. These results suggest that OCA may have an anti-inflammatory effect on radiation-induced intestinal mice by reducing the expression of IL-1β, TNF-α, and IL-6.

(V) OCA promotes the expression of ZO-1 and Occludin in the small intestine of mice with radiation-induced intestinal injury

Tight junction key proteins ZO-1 and Occludin are the most important components of the intestinal mucosal mechanical barrier and are widely distributed between adjacent intestinal epithelial cells. Studies have shown that their expression plays an important role in the repair of intestinal mucosal damage. As shown in Figure 5, compared with the normal control group mice, the expression of key tight junction proteins ZO-1 and occludin in the small intestinal tissue of the irradiated control group mice was significantly reduced, while the expression of key tight junction proteins in the small intestinal tissue of the OCA-administered group mice was higher than that of the irradiated control group.

(VI) OCA promotes the expression of FXR in mice with radiation-induced intestinal injury

The regulatory function of BAs is mainly the result of the activation of intracellular ligand-activated nuclear receptors (NRs), such as farnesoid X receptor (FXR, NR1H4) and cell surface G protein-coupled receptors (GPCRs), especially the G protein-coupled BAs receptor TGR5. In order to gain a deeper understanding of whether the potential mechanism of OCA promoting intestinal regeneration after irradiation involves FXR, mice were irradiated abdominally and given OCA. Five days later, the small intestine and colon tissues of mice were taken for immunohistochemical staining, immunoblotting and qRT-PCR to detect the expression of FXR. The results are shown in Figure 6. After irradiation, the expression level of FXR in the small intestine tissue of mice with radiation-induced intestinal injury was reduced, while OCA could significantly enhance the protein expression level of FXR in the small intestine tissue and colon tissue of mice after irradiation and the mRNA expression level in the small intestine tissue of mice.

Analysis

The small intestine is highly sensitive to radiation and is the main site of injury during radiotherapy for abdominal tumors. Radiation-induced intestinal injury seriously affects the efficacy of tumor radiotherapy and is the main dose-limiting factor for abdominal and pelvic radiotherapy. Currently, there is no effective prevention and treatment method. Therefore, it is of great significance to find an effective drug and protective target to solve radiation-induced intestinal injury.

Obeticholic acid (OCA) is an FXR agonist, a bile acid nuclear receptor that is highly expressed in intestinal tissue and is involved in bile acid homeostasis and intestinal inflammation. In addition to bile acids, many FXR agonists are also under development, and OCA is a potent and selective FXR agonist that has been tested as a treatment option for several liver diseases.

In this study, we observed that OCA has a protective effect on radiation-induced intestinal damage. In the experiment, we found that supplementing with OCA 2 hours before irradiation was beneficial to maintaining the body weight of mice during abdominal irradiation. HE staining of mouse small intestinal tissue sections showed abnormalities in the crypt structure of mice after abdominal irradiation, which was manifested by crypt distortion, atrophy, and irregular surface, disordered glandular structure, and a large number of inflammatory cell infiltration. After OCA was supplemented in abdominal irradiated mice, the intestinal crypt and villus structure was well improved. Radiation-induced tissue damage increased the number of apoptotic cells, and OCA significantly reduced the number of TUNEL-positive cells, indicating that OCA can prevent radiation-induced intestinal damage by alleviating radiation-induced intestinal epithelial cell apoptosis. The proliferation ability of cells is related to the repair of intestinal damage. PCNA and Ki67 are markers of proliferation, representing the self-repair ability of small intestinal cells. OCA treatment promoted the proliferation of intestinal cells after radiation damage in mice. OCA can effectively reduce the expression levels of IL-1β, IL-6, and TNF-α in small intestinal tissues, and has an anti-inflammatory effect on radiation-injured mice. The intestinal mucosal mechanical barrier is the first barrier for the intestine to resist foreign invasion, preventing the invasion of harmful substances in the intestinal cavity and playing an important role in regulating cell permeability. OCA can protect the intestinal epithelial cell barrier by increasing the expression of ZO-1 and Occludin, improving the permeability of intestinal epithelial cells, and further repairing intestinal mucosal damage. Our results showed that the expression of FXR was reduced in mice with radiation-induced intestinal injury, while OCA could promote the expression of FXR in the small intestinal tissue of mice. Activating FXR has a cytoprotective effect and promotes the repair of intestinal damage.

In summary, our study showed that OCA has a protective effect on radiation-induced intestinal injury. We found that OCA alleviated radiation-induced intestinal injury in mice by promoting the expression of FXR. We confirmed that FXR has a preventive and/or therapeutic effect on radiation-induced intestinal injury. At the same time, OCA can improve the apoptosis of small intestinal epithelial cells, thus providing a new therapeutic target for the clinical prevention of radiation-induced intestinal injury. OCA may play an important role in the treatment of radiation-induced intestinal injury in the future.

Claims (7)

1. Application of obeticholic acid in the preparation of drugs for preventing radiation-induced intestinal injury. 2. Application of obeticholic acid in the preparation of drugs for reducing apoptosis of intestinal epithelial cells after radiation. 3. Application of obeticholic acid in the preparation of drugs for the treatment of radiation-induced intestinal injury. 4. Application of obeticholic acid in the preparation of drugs that promote proliferation of intestinal crypts after radiation. 5. Application of obeticholic acid in the preparation of drugs that promote the proliferation of intestinal villus cells after radiation. 6. Application of obeticholic acid in the preparation of drugs for the treatment of post-radiation intestinal inflammation. 7. Application of obeticholic acid in the preparation of drugs for repairing intestinal mucosal damage after radiation.