Lactobacillus crispatus Limits Bladder Uropathogenic E. coli Infection by Triggering a Host Type I Interferon Response

• DOI: 10.1073/pnas.2117904119
• Publication Date: 2022-08-08T19:16:07Z
• Authors: Chang Hyun Song; Young Ho Kim; Manisha Naskar; Byron W. Hayes; Mathew A. Abraham; Joo Hwan Noh; Gyeongseo Suk; Min Jung Kim; Kyu Sang Cho; Minhye Shin; Eun-Jin Lee; Soman N. Abraham; Hae Woong Choi
• Keywords: Male; 0301 basic medicine; Urinary Bladder; Biological Sciences; Cathepsin D; Immunity, Innate; 3. Good health; Biological Therapy; Mice; 03 medical and health sciences; Antibiosis; Interferon Type I; Urinary Tract Infections; Animals; Humans; Uropathogenic Escherichia coli; Female; Lactobacillus crispatus; Escherichia coli Infections

Many urinary tract infections (UTIs) are recurrent because uropathogens persist within the bladder epithelial cells (BECs) for extended periods between bouts of infection. Because persistent uropathogens are intracellular, they are often refractive to antibiotic treatment. The recent discovery of endogenous Lactobacillus spp. in the bladders of healthy humans raised the question of whether these endogenous bacteria directly or indirectly impact intracellular bacterial burden in the bladder. Here, we report that in contrast to healthy women, female patients experiencing recurrent UTIs have a bladder population of Lactobacilli that is markedly reduced. Exposing infected human BECs to L. crispatus in vitro markedly reduced the intracellular uropathogenic Escherichia coli (UPEC) load. The adherence of Lactobacilli to BECs was found to result in increased type I interferon (IFN) production, which in turn enhanced the expression of cathepsin D within lysosomes harboring UPECs. This lysosomal cathepsin D–mediated UPEC killing was diminished in germ-free mice and type I IFN receptor–deficient mice. Secreted metabolites of L. crispatus seemed to be responsible for the increased expression of type I IFN in human BECs. Intravesicular administration of Lactobacilli into UPEC-infected murine bladders markedly reduced their intracellular bacterial load suggesting that components of the endogenous microflora can have therapeutic effects against UTIs.