CD4 and prostatitis: Using mediation analysis, we revealed that various immune cell subsets, including Secreting Treg % CD4 Treg, Activated & resting Treg % CD4 Treg, Mo MDSC AC, CD8 on EM CD8br, CD28- CD25++ CD8br AC, and CD16-CD56 on HLA DR+ NK, exert both protective and detrimental effects on prostate diseases by modulating the abundance of specific bacterial taxa, such as class Mollicutes, genus Eubacterium nodatum group and genus Dorea.