Oral Microbiome and Recovery of Renal Function After Kidney Transplantation.
Objectives: The loss of kidney function that characterizes chronic kidney disease (CKD) leads to dramatic changes in body homeostasis, with repercussions in saliva biochemistry and, consequently, in oral microbiome. Kidney transplant is the gold-standard therapy for patients with end-stage kidney disease. Although oral cavity may represent a starting point for pathogens dissemination and complications after kidney transplantation, such as infections and rejection episodes, few studies evaluated the oral microbiome in kidney transplant recipients (KTR). Therefore, we aimed to explore the impact of kidney transplantation on the oral microbiome.
Methods: We conducted a prospective observational pilot study in patients who received a first living donor kidney transplantation (n=6). The microbiome of saliva was analyzed immediately before (maximum 24h before) and three months after transplantation by sequencing of V3-V4 hypervariable regions of 16S rRNA gene using MiSeq Illumina® technology.
Results: After kidney transplantation the renal function recovered significantly (T3 vs. T0, Glomerular Filtration Rate: 75.3±17.6 vs. 6.2±3.7 mL/min/1.73 m2; Plasma Creatine: 1.0±0.3 vs. 9.0±2.7 mg/dL; Plasma urea: 47.2±13.9 vs. 183.8±30.0 mg/dL, p<0.001 for all parameters). The oral microbiome profile before kidney transplant was dominated by Firmicutes, Bacteroidetes, and Proteobacteria. The recovery of the renal function 3 months after kidney transplant was accompanied by a significant increase in the proportion of Fusobacteria and Proteobacteria and a reduction of Firmicutes and Actinobacteria in saliva. Specifically, the lower taxonomic level analysis revealed increases in bacteria belonging to Escherichia genus and Bradyrhizobiaceae family as well as reduction in bacteria belonging to Streptococcus and Granulicatella genera and unclassified Gemellaceae family.
Conclusions: The recovery of renal function after kidney transplantation is accompanied by changes in oral microbiome, in particular associated with an overgrowth of potentially opportunistic pathogens, including those commonly associated with post-transplant infections.