Expression Profile of MicroRNAs in Breast Milk of Women With Inflammatory Bowel Disease: Correlation With Disease Activity and Medical Treatments

Although most inflammatory bowel disease (IBD) medications are considered safe during pregnancy, their impact on microRNAs (miRNAs) in breast milk is largely unknown. MiRNAs in milk, carried by milk-derived extracellular vesicles (MDEs), are transmitted to the newborn's gut to regulate genes. Aberrant miRNA expression profiles have been found in IBD within tissue, blood, and feces, but data on mother's milk are scarce. We collected breast milk samples from 32 mothers with Crohn's disease (CD), 14 mothers with ulcerative colitis (UC), and 44 healthy controls. We analyzed miRNA expression through qualitative real-time polymerase chain reaction and Affymetrix miRNA chips. Target genes of differentially expressed miRNAs were predicted using miRATBase. Statistical analyses were conducted using GraphPad Prism software with Mann-Whitney tests. Milk-derived extracellular vesicles from mothers with IBD showed altered miRNA profiles compared to controls. Specifically, miR-21 and miR-320 were downregulated, while Let-7a was upregulated in IBD mothers. The expression patterns varied between CD and UC, with significantly lower MiR-21 in UC and higher Let-7a in CD. Additionally, anti-tumor necrosis factor treatment during pregnancy was associated with reduced miR-21 and miR-148a levels in MDEs. Pathway analysis revealed that these miRNAs are involved in immune regulation, particularly interleukin signaling pathways. This study highlights that miRNAs in breast milk are differentially expressed in mothers with IBD, influenced by the disease and its treatments. These findings emphasize the impact of maternal health on milk composition and potential implications for infant immune development. Understanding these findings may guide personalized treatment strategies for mothers and promote breastfeeding among mothers with IBD.