To clinically evaluate the efficacy of patient- and/or donor-derived probiotics in ameliorating intestinal flora dysbiosis in patients with acute intestinal graft-versus-host disease (aGVHD), thereby mechanistically enhancing clinical outcomes and quality of life through intestinal microbiome modulation.

Study Design Overview:

Ten patients aged >50 years scheduled for haploidentical hematopoietic stem cell transplantation (HSCT) will be enrolled. Stool specimens will be collected from both patients and donors (due to frequent depletion of beneficial bacteria in such patients, donor specimens are essential to enhance probiotic detection and cultivation rates). Patient specimens will undergo 16S rDNA intestinal microbiome analysis.

Upon clinical diagnosis of intestinal aGVHD:

1. Pre-collected patient and donor specimens will be homogenized
2. Target isolation and culture of core beneficial bacteria (Lactobacillus and Bifidobacterium)
3. Strain identification via TOF mass spectrometry
4. Fermentation and preparation of 200 enteric-coated capsules (100 Lactobacillus capsules + 100 Bifidobacterium capsules)

Post-intervention assessment (100 days after administration):

Changes in microbiome composition, relative abundance, species diversity, biochemical indicators, and bowel movement characteristics will be evaluated to assess the therapeutic efficacy of patient/donor-derived Lactobacillus and Bifidobacterium in GVHD.

Inclusion Criteria:

Subjects eligible for this study must satisfy all of the following criteria:

1. Age >50 years, regardless of gender;
2. Scheduled for haploidentical hematopoietic stem cell transplantation;
3. ECOG performance status score ≤2;
4. Voluntarily participate and provide written informed consent.

Exclusion Criteria:

Subjects presenting with any of the following conditions will be excluded from this study:

1. Active or chronic infectious diseases, including recent febrile symptoms (axillary temperature ≥37.3°C within 48h);

2. Gastrointestinal disorders:

   • Clostridioides difficile infection (CDI): Recurrent or refractory CDI;
   • Other conditions: Ulcerative colitis, Crohn's disease, irritable bowel syndrome (IBS), diarrhea associated with dysbiosis, liver cirrhosis;

3. Allergic or immune-mediated diseases:

   Autoimmune hepatitis, systemic lupus erythematosus (SLE), ankylosing spondylitis, immune-mediated osteoarthritis, allergic dermatitis, immune thrombocytopenic purpura (ITP);

4. Antibiotic usage within 7 days prior to enrollment.