New Function of Autophagy in C. jejuni Invasion

Campylobacter jejuni is a leading cause of food-borne disease worldwide. The pathogenicity of C. jejuni is closely associated with the internalization process in host epithelial cells, which is related to a host immune response. Autophagy indicates a key role in the innate immune system of the host to exclude invasive pathogens. Most bacteria are captured by autophagosomes and degraded by autophagosome-lysosome fusion in host cells. However, several pathogens, such as Salmonella and Shigella, avoid and/or escape autophagic degradation to establish infection. But autophagy involvement as a host immune response to C. jejuni infection has not been clarified. This study revealed autophagy association in C. jejuni infection. During infection, C. jejuni activated the Rho family small GTPase Rac1 signaling pathway, which modulates actin remodeling and promotes the internalization of this pathogen. In this study, we found the LC3 contribution to C. jejuni invasion signaling via the Rac1 signaling pathway. Interestingly, during C. jejuni invasion, LC3 was recruited to bacterial entry site depending on Rac1 GTPase activation just at the early step of the infection. C. jejuni infection induced LC3-II conversion, and autophagy induction facilitated C. jejuni internalization. Also, autophagy inhibition attenuated C. jejuni invasion step. Moreover, Rac1 recruited LC3 to the cellular membrane, activating the invasion of C. jejuni. Altogether, our findings provide insights into the new function of LC3 in bacterial invasion. We found the interaction between the Rho family small GTPase, Rac1, and autophagy-associated protein, LC3

CFTR associated diarrhea in VP-infection

Vibrio parahaemolyticus is a foodborne bacterium that causes acute gastroenteritis through the consumption of contaminated, raw, or undercooked seafood. Cystic fibrosis transmembrane conductance regulator (CFTR) is a well-characterized chloride channel that regulates several other ion channels and transporters to maintain water homeostasis in the gut lumen. Also, CFTR is a main target of bacterial infection-associated diarrhea. Hence, the aim of this study was to clarify the contribution of CFTR in V. parahaemolyticus-induced diarrhea in a mouse model of intestinal loop fluid accumulation, with CFTR inhibitors and a CFTR knockout model. The results indicated that CFTR plays a critical role in fluid accumulation in response to V. parahaemolyticus infection. We also investigated the inflammatory association in CFTR-mediated V. parahaemolyticus-induced fluid secretion with cyclooxygenase inhibitors and found that fluid accumulation was decreased by inhibition of cyclooxygenase 2 produced by neutrophils. These findings suggest that V. parahaemolyticus-inducing infiltration and activation of neutrophils also participated in CFTR mediated fluid secretion. This study reveals an important relationship between V. parahaemolyticus-induced diarrhea and inflammation in a mouse model

V. parahaemolyticus effector modulates host metabolism

Vibrio parahaemolyticus is a Gram-negative halophilic pathogen that frequently causing acute gastroenteritis and occasional wound infection. V. parahaemolyticus contains several virulent factors, including Type III secretion systems (T3SSs) and thermostable direct hemolysin (TDH). In particular, T3SS1 is a potent cytotoxic inducer, and T3SS2 is essential for causing acute gastroenteritis. Although much is known about V. parahaemolyticus’s effector manipulating host signaling transductions, little is known about the host metabolomic changes modulated by V. parahaemolyticus. To address this knowledge gap, we performed a metabolomic analysis of the epithelial cells during V. parahaemolyticus infection using capillary electrophoresis–time-of-flight mass spectrometry (CE-TOF/MS). Our results revealed significant metabolomic perturbations upon V. parahaemolyticus infection. Moreover, we identified that T3SS1’s VopQ effector was responsible for inducing the significant metabolic changes in the infected cells. The VopQ effector dramatically altered the host cell’s glycolytic, tricarboxylic acid cycle (TCA), amino acid metabolisms. VopQ effector disrupted host cell redox homeostasis by depleting cellular glutathione and subsequently increasing the level of reactive oxygen species (ROS) production

Functions of UPR in Campylobacter jejuni infection

Campylobacter jejuni is a major cause of bacterial foodborne illness in humans worldwide. Bacterial entry into a host eukaryotic cell involves the initial steps of adherence and invasion, which generally activate several cell-signaling pathways that induce the activation of innate defense systems, which leads to the release of proinflammatory cytokines and induction of apoptosis. Recent studies have reported that the unfolded protein response (UPR), a system to clear unfolded proteins from the endoplasmic reticulum (ER), also participates in the activation of cellular defense mechanisms in response to bacterial infection. However, no study has yet investigated the role of UPR in C. jejuni infection. Hence, the aim of this study was to deduce the role of UPR signaling via induction of ER stress in the process of C. jejuni infection. The results suggest that C. jejuni infection suppresses global protein translation. Also, 12 h of C. jejuni infection induced activation of the eIF2α pathway and expression of the transcription factor CHOP. Interestingly, bacterial invasion was facilitated by knockdown of UPR-associated signaling factors and treatment with the ER stress inducers, thapsigargin and tunicamycin, decreased the invasive ability of C. jejuni. An investigation into the mechanism of UPR-mediated inhibition of C. jejuni invasion showed that UPR signaling did not affect bacterial adhesion to or survival in the host cells. Further, Salmonella Enteritidis or FITC-dextran intake were not regulated by UPR signaling. These results indicated that the effect of UPR on intracellular intake was specifically found in C. jejuni infection. These findings are the first to describe the role of UPR in C. jejuni infection and revealed the participation of a new signaling pathway in C. jejuni invasion. UPR signaling is involved in defense against the early step of C. jejuni invasion and thus presents a potential therapeutic target for the treatment of C. jejuni infection

Inactivation of ESBL-E. coli

The prevalence of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli is increasing rapidly and spreading worldwide, particularly in Asia, compared to other regions. In the last ten years, in our hospital, in particular, there has been a < 30% increase. To prevent the spread of ESBL in hospitals and the community, the ultraviolet (UV) A-light-emitting diode (LED) irradiation device was used to inactivate ESBL-E. coli in human livestock and the environment. ESBL-E. coli and E. coli bacterial samples were collected from patients at Tokushima University Hospital (Tokushima City, Japan). The UVA-LED irradiation system had 365 nm single wavelength, and the current of the circuit was set to 0.23 or 0.50 A consistently. Results demonstrated that UVA-LED was useful for the inactivation of ESBL-E. coli and E. coli. The minimum energy dosage required to inactivate ESBL-E. coli and E. coli was 40.76 J/cm2 (45 min) in the first type of UVA-LED and 38.85 J/cm2 (5 min) in the second type. There were no significant differences between ESBL-E. coli and E. coli. The inactivation of ESBL-E. coli was dependent on energy. These findings suggest that UVA-LED with 365 nm single wavelength could be useful for surface decontamination in healthcare facilities

Role of CFTR in Campylobacter jejuni infection

Campylobacter jejuni (C. jejuni) is gastroenteritis inducible food-born pathogen. Invasion and adhesion process are essential for leading gastroenteritis in C. jejuni infection process. As against bacterial strategy for efficacy invasion and adhesion, mucosal layer play a key role in defense systems, which modulated by several ion channels and transporters mediated water flux on the intestine. Cystic fibrosis transmembrane conductance regulator (CFTR) play the main role in waterfulux in intestine, and it closely related with bacterial clearance. We previously reported that C. jejuni infection suppresses CFTR channel activity in intestinal epithelial cells, however the mechanism and importance of this suppression is unclear. This study seeks to elucidate the role of CFTR in C. jejuni-infection. Using HEK293 cells that stably express wild type and mutated CFTR, we found that CFTR attenuated C. jejuni invasion, it was not involved bacterial adhesion or intracellular survival but associated with microtubule-dependent cellular transport. Moreover we revealed that CFTR attenuated function of microtubule motor protein but not microtubule stability, which causes inhibition of C. jejuni-invasion. Meanwhile, the CFTR mutant G551D-CFTR, which has defects in channel activity, suppressed C. jejuni-invasion, whereasΔF508-CFTR, which has defects in maturation, did not suppress, suggesting that CFTR suppression of C. jejuni-invasion is related to CFTR maturation but not channel activity. Taken together, mature CFTR inhibited C. jejuni invasion by regulating microtubule-mediated pathways. We suggest that CFTR plays a critical role in cellular defenses against C. jejuni-invasion, and CFTR suppression may be an initial step in promoting cellular invasion during C. jejuni-infection

Soy protein diet prevents hypermethioninemia caused by portacaval shunt in rats

In hepatic disorders, abnormal plasma amino acid profiles are observed. In this study, we examined whether soy protein isolate (SPI) improved plasma methionine concentration in the model animals. Portacaval shunt (PCS) increased alanine aminotransferase (ALT) activity and methionine concentration in blood of rats fed a 40% casein diet supplemented with 0.6% methionine (casein-M diet). A 40% SPI diet supplemented with 1.28% methionine (SPI-M diet), which contained the same amount of methionine as that in 40% casein-M diet, normalized plasma ALT activity and methionine level in PCS rats. These effects of a SPI diet may be due to its amino acid composition, since an amino acid mixture diet mimicking a 40% SPI-M diet was also effective to hypermethioninemia of PCS rats. To find key enzymes for the beneficial effect of soy protein, we examined effects of a 40% SPI-M or casein-M diet on the activities of three methionine-metabolizing enzymes in liver of PCS rats. A SPI-M diet stimulated only the activity of cystathionine γ-lyase, compared with a casein-M diet. A SPI diet has a preventive effect on hypermethioninemia, at least in part, by stimulating cystathionine γ-lyase activity in liver and may be used for nutritional management of liver disorders with hypermethioninemia

Defective adipose tissue development associated with hepatomegaly in cathepsin E-deficient mice fed a high-fat diet

Cathepsin E is an intracellular aspartic proteinase, which is predominantly distributed in immune-related and epithelial cells. However, the role of the enzyme in adipose tissues remains unknown. In this study, we investigated the characteristics of cathepsin E-deficient (CatE-/-) mice fed a high-fat diet (HFD), as a mouse model of obesity. HFD-fed CatE-/- mice displayed reduced body weight gain and defective development of white adipose tissue (WAT) and brown adipose tissue (BAT), compared with HFD-fed wild-type mice. Moreover, fat-induced CatE-/- mice showed abnormal lipid accumulation in non-adipose tissues characterized by hepatomegaly, which is probably due to defective adipose tissue development. Detailed pathological and biochemical analyses showed that hepatomegaly was accompanied by hepatic steatosis and hypercholesterolemia in HFD-induced CatE-/- mice. In fat-induced CatE-/- mice, the number of macrophages infiltrating into WAT was significantly lower than in fat-induced wild-type mice. Thus, the impaired adipose tissue development in HFD-induced CatE-/- mice was probably due to reduced infiltration of macrophages and may lead to hepatomegaly accompanied by hepatic steatosis and hypercholesterolemia