DUOX2 promotes the elimination of the Klebsiella pneumoniae strain K5 from T24 cells through the reactive oxygen species pathway

Abstract

Dual oxidase 2 (DUOX2) plays a major role in host defense in intestinal and airway epithelial cells through the reactive oxygen species (ROS) pathway. Klebsiella pneumoniae is a uropathogen that causes urinary tract infections. It is not known whether DUOX2 plays a role in host defense in bladder cancer epithelial cells. It is also not known whether Klebsiella pneumoniae invades T24 human bladder carcinoma cells and whether DUOX2 plays a role in eliminating the Klebsiella pneumoniae strain K5 through the ROS pathway in T24 cells. Thus, in the present study, we aimed to investigate the infectious capability of the Klebsiella pneumoniae K5 strain and the immunity-promoting capability of DUOX2 in T24 cells. We quantified the number of viable intracellular bacteria using the plate count method. DUOX2 expression was evaluated by western blot analysis and reverse transcription-quantitative PCR (RT-qPCR) following treatment with or without multiple cytokines, phorbol 12-myristate 13-acetate (PMA), muramyl dipeptide (MDP), N-acetylmuramyl-D-alanyl-D-isoglutamine (MDP-DD), H2O2 inhibitor, catalase (CAT), the nicotinamide adenine dinucleotide phosphate-oxidase (NADPH) oxidase inhibitor, diphenyleneiodonium (DPI), or siRNA targeting DUOX2 (siDUOX2). The levels of ROS in the T24 cells infected with the K5 strain were examined following treatment with DPI, CAT or siDUOX2. Our results revealed that DUOX2 expression increased and the number of viable intracellular bacteria decreased in the T24 cells following infection with the K4 bacteria. Treatment with the cytokines and MDP and PMA also induced DUOX2 expression and decreased the number of viable intracellular bacteria. The levels of ROS also increased following treatment with the cytokines and MDP and PMA. However, when the cells were treated with the inhibitors (DPI or CAT), these effects were all reversed. Our data demonstrated that DUOX2 played an important role in innate immunity against bacterial cytoinvasion through the ROS pathway in T24 cells. Our findings also provide insight into the protection of uroepithelial cells from Klebsiella pneumoniae K5 bacterial cytoinvasion, and thus lay the foundation for the development of novel therapies for urinary tract infections.

NNT mutations: a cause of primary adrenal insufficiency, oxidative stress and extra-adrenal defects

“…This contrasts with the impaired insulin secretion observed in NNT mutant mice for which only the β-cells seemed sensitive (40). Increased ROS usually plays a role in innate immunity against bacterial cytoinvasion (41). Despite that, three of our patients experienced recurrent urinary tract infections.…”

Overexpression of DUOX2 mediates doxorubicin resistance and predicts prognosis of pancreatic cancer

“…Epigenetic silencing of DUOX1 by promoter hypermethylation has been observed in human hepatocellular carcinoma (26). The DUOX2-ROS pathway promotes the elimination of the Klebsiella pneumoniae strain K5 from T24 cells (27). In rectal cancer, overexpression of DUOX2 is associated with poor response to preoperative chemoradiation therapy and clinical prognosis (28).…”

Innate Effector Systems in Primary Human Macrophages Sensitize Multidrug-Resistant Klebsiella pneumoniae to Antibiotics

“…in the normal flora are essential for the protection against K. pneumoniae by a mechanism involving IL-36 signaling and macrophages (17). In addition, the key role of endogenous ROS production against K. pneumoniae has also been established (18). Further, patients with chronic granulomatous disease (CGD), lacking or having severely impaired ROS production, have been shown to suffer from invasive K. pneumoniae infections (19), which underscores that ROS is, indeed, important for physiological growth control of K. pneumoniae in macrophages.…”