Single-housing-induced islet epigenomic changes are related to polymorphisms in diabetic KK mice.

A lack of social relationships is increasingly recognized as a type 2 diabetes (T2D) risk. To investigate the underlying mechanism, we used male KK mice, an inbred strain with spontaneous diabetes. Given the association between living alone and T2D risk in humans, we divided the non-diabetic mice into singly housed (KK-SH) and group-housed control mice. Around the onset of diabetes in KK-SH mice, we compared H3K27ac ChIP-Seq with RNA-Seq using pancreatic islets derived from each experimental group, revealing a positive correlation between single-housing-induced changes in H3K27ac and gene expression levels. In particular, single-housing-induced H3K27ac decreases revealed a significant association with islet cell functions and GWAS loci for T2D and related diseases, with significant enrichment of binding motifs for transcription factors representative of human diabetes. Although these H3K27ac regions were preferentially localized to a polymorphic genomic background, SNVs and indels did not cause sequence disruption of enriched transcription factor motifs in most of these elements. These results suggest alternative roles of genetic variants in environment-dependent epigenomic changes and provide insights into the complex mode of disease inheritance.

Reduction of Campylobacter jejuni contamination by using UVA-LED and sodium hypochlorite on the surface of chicken meat.

Campylobacter jejuni causes gastroenteritis in humans and is a major concern in food safety. Commercially prepared chicken meats are frequently contaminated with C. jejuni, which is closely associated with the diffusion of intestinal contents in poultry processing plants. Sodium hypochlorite (NaClO) is commonly used during chicken processing to prevent food poisoning; however, its antimicrobial activity is not effective in the organic-rich solutions. In this study, we investigated the potential of a new photo-disinfection system, UVA-LED, for the disinfection of C. jejuni-contaminated chicken surfaces. The data indicated that UVA irradiation significantly killed C. jejuni and that its killing ability was significantly facilitated in NaClO-treated chickens. Effective inactivation of C. jejuni was achieved using a combination of UVA and NaClO, even in the organic-rich condition. The results of this study show that synergistic disinfection using a combination of UVA and NaClO has potential beneficial effects in chicken processing systems.

Characterization of Outer Membrane Vesicles Produced by Vibrio vulnificus.

Vibrio vulnificus (V. vulnificus) is a halophilic gram-negative bacterium that inhabits coastal warm water and induce severe diseases such as primary septicemia. To investigate the mechanisms of rapid bacterial translocation on intestinal infection, we focused on outer membrane vesicles (OMVs), which are extracellular vesicles produced by Gram-negative bacteria and deliver virulence factors. However, there are very few studies on the pathogenicity or contents of V. vulnificus OMVs (Vv-OMVs). In this study, we investigated the effects of Vv-OMVs on host cells. Epithelial cells INT407 were stimulated with purified OMVs and morphological alterations and levels of lactate dehydrogenase (LDH) release were observed. In cells treated with OMVs, cell detachment without LDH release was observed, which exhibited different characteristics from cytotoxic cell detachment observed in V. vulnificus infection. Interestingly, OMVs from a Vibrio Vulnificus Hemolysin (VVH) and Multifunctional-autoprocessing repeats-in -toxin (MARTX) double-deletion mutant strain also caused cell detachment without LDH release. Our results suggested that the proteolytic function of a serine protease contained in Vv-OMVs may contribute to pathogenicity of V. vulnificus by assisting bacterial translocation. This study reveals a new pathogenic mechanism during V. vulnificus infections. J. Med. Invest. 71 : 102-112, February, 2024.

Development of a standard evaluation method for microbial UV sensitivity using light-emitting diodes.

Ultraviolet (UV) light is an effective disinfection method. In particular, UV light-emitting diodes (UV-LEDs) are expected to have many applications as light sources owing to their compact form factor and wide range of choices of wavelengths. However, the UV sensitivity of microorganisms for each UV wavelength has not been evaluated comprehensively because standard experimental conditions based on LED characteristics have not been established. Therefore, it is necessary to establish a standard evaluation method based on LED characteristics. Here, we developed a new UV-LED device based on strictly controlled irradiation conditions using LEDs for each wavelength (250-365 nm), checked the validity of the device characteristics and evaluated the UV sensitivity of Escherichia coli using this new evaluation method. For this new device, we considered accurate irradiance, accurate spectra, irradiance uniformity, accurate dose, beam angle, surrounding material reflections, and sample condition. From our results, the following UV irradiation conditions were established as standard: 1 mW/cm2 irradiance, bacterial solution with absorbance value of A600 = 0.5 diluted 10 times solution, solution volume of 1 mL, working distance (WD) of 100 mm. In order to compare the effects of irradiation under uniform conditions on inactivation of microorganisms, we assessed inactivation effect of E. coli by LED irradiation at each wavelength using the U280 LED as a standard wavelength. The inactivation effect for U280 LED irradiation was -0.95 ± 0.21 log at a dose of 4 mJ/cm2. Under this condition of dose, our results showed a high wavelength dependence of the inactivation effect at each UV wavelength peaking at 267 nm. Our study showed that this irradiation system was validated for the standard UV irradiation system and could be contributed to the establishment of food and water hygiene control methods and the development of equipment for the prevention of infectious diseases.

SLC16a6, mTORC1, and Autophagy Regulate Ketone Body Excretion in the Intestinal Cells.

Ketone bodies serve several functions in the intestinal epithelium, such as stem cell maintenance, cell proliferation and differentiation, and cancer growth. Nevertheless, there is limited understanding of the mechanisms governing the regulation of intestinal ketone body concentration. In this study, we elucidated the factors responsible for ketone body production and excretion using shRNA-mediated or pharmacological inhibition of specific genes or functions in the intestinal cells. We revealed that a fasting-mimicked culture medium, which excluded glucose, pyruvate, and glutamine, augmented ketone body production and excretion in the Caco2 and HT29 colorectal cells. This effect was attenuated by glucose or glutamine supplementation. On the other hand, the inhibition of the mammalian target of rapamycin complex1 (mTORC1) recovered a fraction of the excreted ketone bodies. In addition, the pharmacological or shbeclin1-mediated inhibition of autophagy suppressed ketone body excretion. The knockdown of basigin, a transmembrane protein responsible for targeting monocarboxylate transporters (MCTs), such as MCT1 and MCT4, suppressed lactic acid and pyruvic acid excretion but increased ketone body excretion. Finally, we found that MCT7 (SLC16a6) knockdown suppressed ketone body excretion. Our findings indicate that the mTORC1-autophagy axis and MCT7 are potential targets to regulate ketone body excretion from the intestinal epithelium.

Dietary phosphate disturbs of gut microbiome in mice.

Disorder of phosphate metabolism is a common pathological condition in chronic kidney disease patients. Excessive intake of dietary phosphate deteriorates chronic kidney disease and various complications including cardiovascular and infectious diseases. Recent reports have demonstrated that gut microbiome disturbance is associated with both the etiology and progression of chronic kidney disease. However, the relationship between dietary phosphate and gut microbiome remains unknown. Here, we examined the effects of excessive intake of phosphate on gut microbiome. Five-week-old male C57BL/6J mice were fed either control diet or high phosphate diet for eight weeks. Analysis of the gut microbiota was carried out using MiSeq next generation sequencer, and short-chain fatty acids were determined with GC-MS. In analysis of gut microbiota, significantly increased in Erysipelotrichaceae and decreased in Ruminococcaceae were observed in high phosphate diet group. Furthermore, high phosphate diet induced reduction of microbial diversity and decreased mRNA levels of colonic tight junction markers. These results suggest that the excessive intake of dietary phosphate disturbs gut microbiota and affects intestinal barrier function.

Glucocorticoid receptor-NECAB1 axis can negatively regulate insulin secretion in pancreatic ß-cells.

The mechanisms of impaired glucose-induced insulin secretion from the pancreatic ß-cells in obesity have not yet been completely elucidated. Here, we aimed to assess the effects of adipocyte-derived factors on the functioning of pancreatic ß-cells. We prepared a conditioned medium using 3T3-L1 cell culture supernatant collected at day eight (D8CM) and then exposed the rat pancreatic ß-cell line, INS-1D. We found that D8CM suppressed insulin secretion in INS-1D cells due to reduced intracellular calcium levels. This was mediated by the induction of a negative regulator of insulin secretion-NECAB1. LC-MS/MS analysis results revealed that D8CM possessed steroid hormones (cortisol, corticosterone, and cortisone). INS-1D cell exposure to cortisol or corticosterone increased Necab1 mRNA expression and significantly reduced insulin secretion. The increased expression of Necab1 and reduced insulin secretion effects from exposure to these hormones were completely abolished by inhibition of the glucocorticoid receptor (GR). NECAB1 expression was also increased in the pancreatic islets of db/db mice. We demonstrated that the upregulation of NECAB1 was dependent on GR activation, and that binding of the GR to the upstream regions of Necab1 was essential for this effect. NECAB1 may play a novel role in the adipoinsular axis and could be potentially involved in the pathophysiology of obesity-related diabetes mellitus.

Effects of the loss of maternal gut microbiota before pregnancy on gut microbiota, food allergy susceptibility, and epigenetic modification on subsequent generations.

Maternal environments affect the health of offspring in later life. Changes in epigenetic modifications may partially explain this phenomenon. The gut microbiota is a critical environmental factor that influences epigenetic modifications of host immune cells and the development of food allergies. However, whether changes in the maternal gut microbiota affect the development of food allergies and related epigenetic modifications in subsequent generations remains unclear. Here, we investigated the effects of antibiotic treatment before pregnancy on the development of the gut microbiota, food allergies, and epigenetic modifications in F1 and F2 mice. We found that pre-conception antibiotic treatment affected the gut microbiota composition in F1 but not F2 offspring. F1 mice born to antibiotic-treated mothers had a lower proportion of butyric acid-producing bacteria and, consequently, a lower butyric acid concentration in their cecal contents. The methylation level in the DNA of intestinal lamina propria lymphocytes, food allergy susceptibility, and production of antigen-specific IgE in the F1 and F2 mice were not different between those born to control and antibiotic-treated mothers. In addition, F1 mice born to antibiotic-treated mothers showed increased fecal excretion related to the stress response in a novel environment. These results suggest that the maternal gut microbiota is effectively passed onto F1 offspring but has little effect on food allergy susceptibility or DNA methylation levels in offspring.

Characteristic Metabolic Changes in Skeletal Muscle Due to Vibrio vulnificus Infection in a Wound Infection Model.

Vibrio vulnificus is a bacterium that inhabits warm seawater or brackish water environments and causes foodborne diseases and wound infections. In severe cases, V. vulnificus invades the skeletal muscle tissue, where bacterial proliferation leads to septicemia and necrotizing fasciitis with high mortality. Despite this characteristic, information on metabolic changes in tissue infected with V. vulnificus is not available. Here, we elucidated the metabolic changes in V. vulnificus-infected mouse skeletal muscle using capillary electrophoresis time-of-flight mass spectrometry (CE-TOFMS). Metabolome analysis revealed changes in muscle catabolites and energy metabolites during V. vulnificus infection. In particular, succinic acid accumulated but fumaric acid decreased in the infected muscle. However, the virulence factor deletion mutant revealed that changes in metabolites and bacterial proliferation were abolished in skeletal muscle infected with a multifunctional-autoprocessing repeats-in-toxin (MARTX) mutant. On the other hand, mice that were immunosuppressed via cyclophosphamide (CPA) treatment exhibited a similar level of bacterial counts and metabolites between the wild type and MARTX mutant. Therefore, our data indicate that V. vulnificus induces metabolic changes in mouse skeletal muscle and proliferates by using the MARTX toxin to evade the host immune system. This study indicates a new correlation between V. vulnificus infections and metabolic changes that lead to severe reactions or damage to host skeletal muscle. IMPORTANCE V. vulnificus causes necrotizing skin and soft tissue infections (NSSTIs) in severe cases, with high mortality and sign of rapid deterioration. Despite the severity of the infection, the dysfunction of the host metabolism in skeletal muscle triggered by V. vulnificus is poorly understood. In this study, by using a mouse wound infection model, we revealed characteristic changes in muscle catabolism and energy metabolism in skeletal muscle associated with bacterial proliferation in the infected tissues. Understanding such metabolic changes in V. vulnificus-infected tissue may provide crucial information to identify the mechanism via which V. vulnificus induces severe infections. Moreover, our metabolite data may be useful for the recognition, identification, or detection of V. vulnificus infections in clinical studies.

The Polymethoxyflavone Sudachitin Modulates the Circadian Clock and Improves Liver Physiology.

SCOPE: Polymethoxylated flavones (PMFs) are a group of natural compounds known to display a wide array of beneficial effects to promote physiological fitness. Recent studies reveal circadian clocks as an important cellular mechanism mediating preventive efficacy of the major PMF Nobiletin against metabolic disorders. Sudachitin is a PMF enriched in Citrus sudachi, and its functions and mechanism of action are poorly understood. METHODS AND RESULTS: Using circadian reporter cells, it shows that Sudachitin modulates circadian amplitude and period of Bmal1 promoter-driven reporter rhythms, and real-time qPCR analysis shows that Sudachitin alters expression of core clock genes, notably Bmal1, at both transcript and protein levels. Mass-spec analysis reveals systemic exposure in vivo. In mice fed with high-fat diet with or without Sudachitin, it observes increased nighttime activity and daytime sleep, accompanied by significant metabolic improvements in a circadian time-dependent manner, including respiratory quotient, blood lipid and glucose profiles, and liver physiology. Focusing on liver, RNA-sequencing and metabolomic analyses reveal prevalent diurnal alteration in both gene expression and metabolite accumulation. CONCLUSION: This study elucidates Sudachitin as a new clock-modulating PMF with beneficial effects to improve diurnal metabolic homeostasis and liver physiology, suggesting the circadian clock as a fundamental mechanism to safeguard physiological well-being.

Effect of T1R3 Taste Receptor Gene Deletion on Dextran Sulfate Sodium-Induced Colitis in Mice.

Taste receptor type 1 member 3 (T1R3) recognize umami or sweet tastes and also contributes type 2 immunity and autophagy in small intestine and muscle cells, respectively. Since imbalance of type 1 and type 2 immunity and autophagy affect intestinal bowel disease (IBD), we hypothesized that T1R3 have a potential role in the incidence and progression of colitis. In the present study, we investigated whether genetic deletion of T1R3 impacted aggravation of DSS-induced colitis in mice. We found that T1R3-KO mice showed reduction in colon damage, including reduced inflammation and colon shrinking relative to those of WT mice following DSS treatment. mRNA expression of tight junction components, particularly claudin1 was significantly lower in T1R3-KO mice with trend to lower inflammation related gene mRNA expression in colon. Other parameters, such as response to microbial stimuli in splenic lymphocytes and peritoneal macrophages, gut microbiota composition, and expression of autophagy-related proteins, were similar between WT and KO mice. Together, these results indicated that deletion of T1R3 has a minor role in intestinal inflammation induced by DSS-induced acute colitis in mice.

Recruitment of LC3 by Campylobacter jejuni to Bacterial Invasion Site on Host Cells via the Rac1-Mediated Signaling Pathway.

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.

UV-LED irradiation reduces the infectivity of herpes simplex virus type 1 by targeting different viral components depending on the peak wavelength.

Herpes simplex virus type 1 (HSV-1) is an enveloped virus that mainly infects humans. Given its high global prevalence, disinfection is critical for reducing the risk of infection. Ultraviolet-light-emitting diodes (UV-LEDs) are eco-friendly irradiating modules with different peak wavelengths, but the molecules degraded by UV-LED irradiation have not been clarified. To identify the target viral molecules of UV-LEDs, we exposed HSV-1 suspensions to UV-LED irradiation at wavelengths of 260-, 280-, 310-, and 365-nm and measured viral DNA, protein, and lipid damage and infectivity in host cells. All UV-LEDs substantially reduced by inhibiting host cell transcription, but 260- and 280-nm UV-LEDs had significantly stronger virucidal efficiency than 310- and 365-nm UV-LEDs. Meanwhile, 260- and 280-nm UV-LEDs induced the formation of viral DNA photoproducts and the degradation of viral proteins and some phosphoglycerolipid species. Unlike 260- and 280-nm UV-LEDs, 310- and 365-nm UV-LEDs decreased the viral protein levels, but they did not drastically change the levels of viral DNA photoproducts and lipophilic metabolites. These results suggest that UV-LEDs reduce the infectivity of HSV-1 by targeting different viral molecules based on the peak wavelength. These findings could facilitate the optimization of UV-LED irradiation for viral inactivation.

Effect of Vitamin B2-Deficient Diet on Hydroxyproline- or Obesity-Induced Hyperoxaluria in Mice.

SCOPE: Hyperoxaluria is a major cause of kidney stone disease. Around half of the oxalate in mammals is supplied from the diet and the other half is endogenously synthesized from glyoxylate. Reduction of hepatic glycolate oxidase (GO) activity is one approach to reduce endogenous production of oxalate. However, there are currently few effective dietary approaches to reduce hepatic GO activity. METHODS AND RESULTS: In the present study, it is investigated whether restriction of dietary vitamin B2 (VB2) can reduce hepatic GO activity and oxalate excretion in mice with hyperoxaluria induce by hydroxyproline (Hyp) or obesity. It is found that VB2 restriction significantly reduces hepatic GO activity in both the Hyp- and obesity-induced model of hyperoxaluria in mice. However, VB2 restriction reduces urinary oxalate excretion only in the Hyp-treated mice and not the obese mice. This difference could be due to the contribution of endogenous oxalate production that manifests as increased hepatic GO activity in Hyp-treated mice but not obese mice. CONCLUSION: Together these results suggest that VB2 restriction could be a new dietary approach to improve hyperoxaluria when endogenous production of oxalate is increased.

Vibrio parahaemolyticus induces inflammation-associated fluid accumulation via activation of the cystic fibrosis transmembrane conductance regulator.

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. J. Med. Invest. 68 : 59-70, February, 2021.

Functional Roles of B-Vitamins in the Gut and Gut Microbiome.

The gut microbiota produce hundreds of bioactive compounds, including B-vitamins, which play significant physiological roles in hosts by supporting the fitness of symbiotic species and suppressing the growth of competitive species. B-vitamins are also essential to the host and certain gut bacterium. Although dietary B-vitamins are mainly absorbed from the small intestine, excess B-vitamins unable to be absorbed in the small intestine are supplied to the distal gut. In addition, B-vitamins are supplied from biosynthesis by distal gut microbiota. B-vitamins in the distal colon may perform many important functions in the body. They act as 1) nutrients for a host and their microbiota, 2) regulators of immune cell activity, 3) mediators of drug efficacy, 4) supporters of survival, or the fitness of certain bacterium, 5) suppressors of colonization by pathogenic bacteria, and 6) modulators of colitis. Insights into basic biophysical principles, including the bioavailability of B-vitamins and their derivatives in the distal gut are still not fully elucidated. Here, the function of single B-vitamin in the distal gut including their roles in relation to bacteria are briefly reviewed. The prospect of extending analytical methods to better understand the role of B-vitamins in the gut is also explored.

Irradiation by a Combination of Different Peak-Wavelength Ultraviolet-Light Emitting Diodes Enhances the Inactivation of Influenza A Viruses.

Influenza A viruses (IAVs) pose a serious global threat to humans and their livestock. This study aimed to determine the ideal irradiation by ultraviolet-light emitting diodes (UV-LEDs) for IAV disinfection. We irradiated the IAV H1N1 subtype with 4.8 mJ/cm2 UV using eight UV-LEDs [peak wavelengths (WL) = 365, 310, 300, 290, 280, 270, and 260 nm)] or a mercury low pressure (LP)-UV lamp (Peak WL = 254 nm). Inactivation was evaluated by the infection ratio of Madin-Darby canine kidney (MDCK) cells or chicken embryonated eggs. Irradiation by the 260 nm UV-LED showed the highest inactivation among all treatments. Because the irradiation-induced inactivation effects strongly correlated with damage to viral RNA, we calculated the correlation coefficient (RAE) between the irradiant spectrum and absorption of viral RNA. The RAE scores strongly correlated with the inactivation by the UV-LEDs and LP-UV lamp. To increase the RAE score, we combined three different peak WL UV-LEDs (hybrid UV-LED). The hybrid UV-LED (RAE = 86.3) significantly inactivated both H1N1 and H6N2 subtypes to a greater extent than 260 nm (RAE = 68.6) or 270 nm (RAE = 42.2) UV-LEDs. The RAE score is an important factor for increasing the virucidal effects of UV-LED irradiation.

Inactivation of Extended-spectrum ß-lactamase (ESBL)-producing Escherichia coli by UVA-LED irradiation system.

The prevalence of extended-spectrum ß-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. J. Med. Invest. 67 : 163-169, February, 2020.

Type III Secretion Effector VopQ of Vibrio parahaemolyticus Modulates Central Carbon Metabolism in Epithelial Cells.

Vibrio parahaemolyticus is a Gram-negative halophilic pathogen that frequently causes acute gastroenteritis and occasional wound infection. V. parahaemolyticus contains several virulence 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 manipulation of host signaling transductions by the V. parahaemolyticus effector, 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), and 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.IMPORTANCE The metabolic response of host cells upon infection is pathogen specific, and infection-induced host metabolic reprogramming may have beneficial effects on the proliferation of pathogens. V. parahaemolyticus contains a range of virulence factors to manipulate host signaling pathways and metabolic processes. In this study, we identified that the T3SS1 VopQ effector rewrites host metabolism in conjunction with the inflammation and cell death processes. Understanding how VopQ reprograms host cell metabolism during the infection could help us to identify novel therapeutic strategies to enhance the survival of host cells during V. parahaemolyticus infection.

Glycolate is a Novel Marker of Vitamin B2 Deficiency Involved in Gut Microbe Metabolism in Mice.

Microbes in the human gut play a role in the production of bioactive compounds, including some vitamins. Although several studies attempted to identify definitive markers for certain vitamin deficiencies, the role of gut microbiota in these deficiencies is unclear. To investigate the role of gut microbiota in deficiencies of four vitamins, B2, B6, folate, and B12, we conducted a comprehensive analysis of metabolites in mice treated and untreated with antibiotics. We identified glycolate (GA) as a novel marker of vitamin B2 (VB2) deficiency, and show that gut microbiota sense dietary VB2 deficiency and accumulate GA in response. The plasma GA concentration responded to reduced VB2 supply from both the gut microbiota and the diet. These results suggest that GA is a novel marker that can be used to assess whether or not the net supply of VB2 from dietary sources and gut microbiota is sufficient. We also found that gut microbiota can provide short-term compensation for host VB2 deficiency when dietary VB2 is withheld.