Urolithin A attenuates cyclophosphamide-induced gut microbiota dysbiosis in rats through modulation of Nrf2/HO-1 and TLR4/NF-κB signaling pathways: a 16S rRNA-based study

Introduction: The mechanisms by which cyclophosphamide can alter intestinal homeostasis include oxidative stress, inflammatory signalling, and changes in the gut microbiota. Objective: This study aimed to evaluate the effects of Urolithin A on gut dysbiosis and molecular changes in rats induced by cyclophosphamide. Methods: There were four groups of animals: Control (T1), cyclophosphamide 50 mg/kg (T2), cyclophosphamide plus Urolithin A 25 mg/kg/day (T3), and cyclophosphamide plus Urolithin A 50 mg/kg/day (T4), with 60 albino rats in total. The relative expression of mRNA for Nrf2, HO-1, TLR4, and NF-κB was measured by RT-qPCR, and the composition and diversity of gut microbes were measured by 16S rRNA gene sequencing. Results: Cyclophosphamide reduced Nrf2 expression from 1.00 ± 0.04 to 0.42 ± 0.03 and HO-1 from 1.00 ± 0.06 to 0.48 ± 0.04, while increasing TLR4 to 2.89 ± 0.07 and NF-κB to 3.17 ± 0.12. High-dose Urolithin A increased Nrf2 and HO-1 to 1.05 ± 0.06 and 1.13 ± 0.04 and reduced TLR4 and NF-κB to 1.16 ± 0.06 and 1.26 ± 0.07, respectively. Cyclophosphamide also appeared to negatively affect the levels of Lactobacillus and Bifidobacterium, increase the levels of Escherichia coli and Enterococcus, decrease the diversity and richness of microbes, and increase the ratio of Firmicutes to Bacteroidetes in the gut. In general, the higher dose of Urolithin A (50 mg/kg) showed values that were more closely comparable to those of the control group, though the effect of Urolithin A was only seen in a dose-associated manner. Conclusion: The results here suggest that Urolithin A could attenuate the molecular and microbial disruptions of the intestine induced by cyclophosphamide, but more mechanistic work is needed to confirm causality and protein-level activity of the pathways.