Background and Purpose: Chronic cholecystitis is a common disease causing gallbladder inflammation, which is closely related to imbalances in gut bacteria and bile acids. This study aims to investigate whether consuming a special functional yogurt containing the probiotic Pediococcus acidilactici GR-5 can help alleviate the symptoms of chronic cholecystitis.

Study Procedures: Researchers will recruit 50 patients with chronic cholecystitis and randomly divide them into two groups. For 30 days, one group will consume the functional GR-5 probiotic yogurt, while the other group will consume regular commercial yogurt (placebo). During the study period, researchers will use abdominal imaging to check the gallbladder, evaluate clinical symptoms, and collect blood and stool samples at baseline and after the 30-day intervention. The goal is to see if this probiotic yogurt can improve gallbladder health by regulating gut bacteria and bile acid metabolism, potentially providing a new dietary and nutritional option for patients with cholecystitis.

Scientific Background: The pathogenesis of chronic cholecystitis is closely associated with the accumulation of conjugated bile acids and the dysbiosis of gut microbiota. Previous studies indicate that Pediococcus acidilactici GR-5, a probiotic isolated from traditional fermented foods, possesses high bile salt hydrolase (BSH) activity. It can efficiently deconjugate bile acids, thereby potentially reducing cytotoxicity and inflammatory stimulation in the gallbladder mucosa. This study aims to evaluate the clinical efficacy and underlying mechanisms of GR-5 functional yogurt in managing chronic cholecystitis via the "gut-biliary axis."

Study Design and Intervention: This is a prospective, randomized, double-blind, placebo-controlled clinical trial. Eligible patients diagnosed with chronic cholecystitis will be randomly assigned in a 1:1 ratio to receive either the functional GR-5 probiotic yogurt (intervention group) or an ordinary yogurt without GR-5 (control group) for 30 days. To ensure strict double-blinding, an independent third party will handle the generation of the random sequence and the de-identified packaging. Both yogurt products will be completely identical in appearance, color, smell, and taste.

Data Collection and Multi-omics Analysis: The observation period spans 30 days. At baseline (Day 0) and at the end of the intervention (Day 30), researchers will conduct clinical evaluations, morphological imaging of the biliary tract, and collect fasting peripheral blood and fecal samples. To explore the deep mechanisms, multi-omics technologies, including 16S rRNA high-throughput sequencing and targeted/untargeted metabolomics of bile acids, will be utilized. By dynamically monitoring the changes in the gut microbiome and bile acid metabolic profiles before and after the intervention, this study expects to provide scientific evidence for using targeted functional microecological therapies to reshape intestinal homeostasis and alleviate biliary inflammation.

Inclusion Criteria:

• Male or female, aged 18 to 70 years.
• Definitive diagnosis of chronic cholecystitis (with or without gallstones), referencing the Chinese Medical Association guidelines or relevant clinical diagnostic criteria.
• Presence of clinical symptoms including recurrent right upper quadrant discomfort or dull pain, or accompanying dyspeptic symptoms (such as abdominal bloating, belching, or nausea), with symptoms persisting or recurring for more than 3 months prior to enrollment.
• Imaging support: Abdominal ultrasound within 3 months prior to enrollment indicating gallbladder wall thickening (typically > 3 mm) or wall roughness.
• Voluntary participation and signed written informed consent form.

Exclusion Criteria:

• Acute exacerbation of cholecystitis, purulent or gangrenous cholecystitis, or accompanying biliary obstruction or severe cholangitis requiring emergency surgical intervention.
• History of cholecystectomy or other major gastrointestinal surgeries (e.g., gastric bypass, bowel resection).
• Comorbidities of other severe primary diseases or malignancies, including: severe cardiovascular, renal, or neurological diseases; severe liver diseases (e.g., cirrhosis, severe viral hepatitis); and malignancies (e.g., gallbladder cancer, gastrointestinal tumors).
• Pregnant or lactating women, or those planning to conceive during the study period.
• Use of the following medications or preparations within 4 weeks prior to enrollment: continuous use of antibiotics, other probiotic or prebiotic preparations; currently taking choleretic or litholytic drugs that may significantly affect bile acid metabolism (e.g., ursodeoxycholic acid).
• Known allergy to dairy products, yogurt, or any intervention ingredients, or having severe lactose intolerance.
• Any other conditions that, in the opinion of the investigator, make the subject unsuitable for participation in this clinical study.

To protect the privacy and confidentiality of the study participants, individual participant data (IPD) will not be shared.