CD28 and chronic kidney disease: As shown in Table 1, we found that, in MiBioGen dataset, “CD3 on CD28 + CD4-CD8- T cell” and “Naive-mature B cell Absolute Count” exhibited mediation in the causal association between Coprococcus and CKD, with a mediation proportion of 7.33 and 6.62(p < 0.05).