Bacterial pathogens have evolved multiple strategies to disassemble epithelial cell apical junctional complexes (AJCs) and infect epithelial cells. Leptospirosis is a widespread zoonotic infection, mainly caused by Leptospira interrogans, and its dissemination across host cell barriers is essential for its pathogenesis. However, the mechanism of bacterial dissemination across epithelial cell barriers remains poorly characterised. In this study, we analysed the interaction of L. interrogans with renal proximal tubule epithelial cells (RPTECs) and found that at 24 hr post‐infection, L. interrogans remain in close contact with the plasma membrane of the RPTEC by extracellularly adhering or crawling. Leptospira interrogans cleaved E‐cadherin and induced its endocytosis with release of the soluble N‐terminal fragment into the extracellular medium. Concomitantly, a gradual decrease in transepithelial electrical resistance (TEER), mislocalisation of AJC proteins (occludin, claudin‐10, ZO‐1, and cingulin) and cytoskeletal rearrangement were observed. Inhibition of clathrin‐mediated E‐cadherin endocytosis prevented the decrease in TEER. We showed that disassembly of AJCs in epithelial cells and transmigration of bacteria through the paracellular route are important for the dissemination of L. interrogans in the host.

Focused ion beam-scanning electron microscopy image of renal proximal tubule epithelial cells infected for 24 hrs with Leptospira interrogans. Leptospires localized in the gap between two adjacent ce...

Two new steroid sulfates 1 and 2 were obtained from a lipophilic extract of an undescribed bryozoan species in the genus Calyptotheca. The structures of compounds 1 and 2 were elucidated by spectroscopic methods and chemical modifications. Steroids 1 and 2 exhibited moderate cytotoxicity at IC₅₀ 54 and 30 µM, respectively, against NBT-T2 cells.

Background/Objectives: Methylglyoxal (MGO) and subsequent activation of advanced glycation end products (AGEs)–RAGE receptor signaling has been implicated in the complications of diabetes mellitus (DM), such as bladder dysfunction. Chronic treatment with MGO leads to bladder overactivity, but the effects of acute MGO exposure have not yet been evaluated. Methods: In this study, we used female wild-type, endothelial nitric oxide (eNOS) knockout (eNOS^−/−), and triple (neuronal/endothelial/inducible) NOS^−/− mice to investigate the effects of incubation of MGO (10 to 300 µM) on bladder contractions induced by carbachol and electrical field stimulation (EFS). We also analyzed the activity of the MGO detoxification enzyme glyoxalase 1 (Glo1). Results: Incubation with MGO at 10 and 30 µM in urothelium-intact preparations produced marked detrusor hypercontractility to both carbachol and EFS that was abolished by urothelium removal. Detrusor hypercontractility was associated with the generation of reactive oxygen species (ROS), RAGE activation, Rho kinase sensitization, and activation of TRPA1 and TRPV4 channels. At higher concentrations (100 and 300 µM), MGO did not significantly affect the detrusor contractility to carbachol and EFS, but L-NAME pretreatment restored the hypercontractile state by MGO. Likewise, in bladder strips obtained from eNOS^−/− or triple NOS^−/− mice, MGO exposure (300 µM) significantly enhanced carbachol and EFS-induced contractions, indicating a major role for nitric oxide (NO) counteracting the hypercontractility. No concentration of MGO altered Glo1 activity in bladder tissues. Conclusions: In conclusion, progressive MGO accumulation may account for the transition from the initial hyperactive phase to the subsequent hypoactive decompensated phase of diabetic bladder dysfunction.