Gut microbiota dysbiosis mediates mouse kidney fibrosis induced by black phosphorus quantum dots

As a novel type of nanomaterials, black phosphorus quantum dots (BPQDs) have wide application potential, including anti-pathogenic bacteria. However, there is no information on the effects of BPQDs on the symbiotic bacteria after oral exposure. In our study, mice were daily oral administrated to 0.1 and 1 mg/kg BPQDs for 28 days. We found that BPQDs caused gut microbiota dysbiosis and decreased the abundance of Lactobacillus. From the in vitro experiments, we demonstrated that BPQDs inhibited the growth of Lactobacillus via disrupting bacterial cell membrane. Besides, we found that BPQDs oral exposure caused T cell activation, inflammation, and fibrosis in kidneys. Notably, there was no any kidney injury in BPQD-exposed germ-free mice, which proved that gut microbiota mediated BPQD-caused kidney injury. Moreover, supplementation of probiotic Lactobacillus reuteri (L. reu) and a commercial probiotic containing Lactobacillus, could rescue the kidney injury caused by BPQD exposure. As one of the beneficial metabolites of Lactobacillus, the content of acetic acid was decreased after BPQD exposure, which was recovered by probiotic supplementation. Finally, acetic acid treatment also attenuated the kidney injury. In conclusion, this study illustrates that BPQD oral exposure can cause gut microbiota dysbiosis and decrease the abundance of Lactobacillus and the content of acetic acid, all of which might mediate the renal inflammation and fibrosis. Our work suggests that the supplementation of Lactobacillus and their metabolites would be potential intervention approaches for alleviating the remote organ injury caused by nanomaterials.