The structural and functional destruction of the blood-testis barrier (BTB) following uropathogenic E. coli (UPEC)
infection may be a critical component of the pathologic progress of
orchitis. Recent findings indicate that the mammalian target of the
rapamycin (mTOR)-signaling pathway is implicated in the regulation of BTB assembly and restructuring. To explore the mechanisms underlying BTB damage induced by UPEC
infection, we analyzed BTB integrity and the involvement of the mTOR-signaling pathway using in vivo and in vitro UPEC-
infection models. We initially confirmed that soluble virulent factors secreted from UPEC trigger a stress response in Sertoli cells and disturb adjacent cell junctions via down-regulation of junctional
proteins, including
occludin, zonula occludens-1 (ZO-1),
F-actin, connexin-43 (CX-43), β-
catenin, and
N-cadherin. The BTB was ultimately disrupted in UPEC-infected rat testes, and blood samples from UPEC-induced
orchitis in these animals were positive for anti-sperm
antibodies. Furthermore, we herein also demonstrated that mTOR complex 1 (
mTORC1) over-activation and
mTORC2 suppression contributed to the disturbance in the balance between BTB "opening" and "closing." More importantly,
rapamycin (a specific
mTORC1 inhibitor) significantly restored the expression of cell-junction
proteins and exerted a protective effect on the BTB during UPEC
infection. We further confirmed that short-term treatment with
rapamycin did not aggravate spermatogenic degeneration in infected rats. Collectively, this study showed an association between abnormal activation of the mTOR-signaling pathway and BTB impairment during UPEC-induced
orchitis, which may provide new insights into a potential treatment strategy for testicular
infection.