Table 2 Functional roles of selected microbes in PCa

Cutibacterium acnes

Induce secretion of cytokines and chemokines such as IL-6 and IL-8 [70, 71], activate transcription factors such as NF-κB and STAT3 [70], and induce production of reactive oxygen species [75], all leading to chronic inflammation and pre-cancerous transformation of the prostatic epithelia.

E.coli

Chronic inflammation and tissue damage mediated by CNF1 [81].

Faecalibacterium prausnitzii

Down-regulation of pro-inflammatory cytokines TNF-α, TNF-β and IL-6 [82], and increased production of anti-inflammatory cytokine IL-10 [83] in normal tissue.

Ruminococcus gnavus

Convert androgen precursors to active androgen enabling alternative source of androgens and resulting in treatment resistance and disease progression [84].