Comprehensive overview of the complex gut microbiota–miRNA crosstalk in immunocompromised pediatric patients

Immunocompromised pediatric patients, particularly those diagnosed with leukemia, often experience immune suppression due to prolonged use of immunosuppressive medication and chemotherapy. Consequently, these patients are highly vulnerable to infections caused by both pathogenic and non-pathogenic microorganisms. To prevent such infections, antibiotics and antifungals are routinely administered as prophylactic treatments. However, the use of antimicrobials significantly impacts the patient's microbiota, particularly the gut microbiota, which plays a crucial role in immunomodulating the mucosa and maintaining the integrity of the intestinal epithelium. Disruption of these functions may transform the intestinal epithelium into a potential entry point for harmful microorganisms. The regulation of gut homeostasis and the composition of the intestinal microbiota have been linked to different host-derived microRNAs (miRNAs) that regulate gene expression. Intestinal epithelial cells release miRNAs into the lumen, where they modulate the growth of gut microbes and the microbiota's composition. This review summarizes current insights into the relationship between the gut microbiota and intestinal miRNAs, emphasizing their potential as diagnostic and prognostic biomarkers for immunocompromised pediatric patients.