In conclusion, despite the limitations mentioned above, this study demonstrates that aberrant gut microbiota in patients with CKD, especially K. pneumoniae, contributes to the pathogenesis of UCM through the induction of heart-infiltrating IFNγ+ CD4+ T cells expansion, suggesting that manipulation of the gut microbiome may serve as a promising target for the amelioration of UCM. Here, CD4 is linked to chronic kidney disease.