The gut microbiota engages different signaling pathways to induce Duox2 expression in the ileum and colon epithelium

Neonatal microbiota colonization primes maturation of goblet cell-mediated protection in the pre-weaning colon

Regulated host-microbe interactions are a critical aspect of lifelong health. Colonic goblet cells protect from microorganisms via the generation of a mucus barrier structure. Bacteria-sensing sentinel goblet cells provide secondary protection by orchestrating mucus secretion when microbes breach the mucus barrier. Mucus deficiencies in germ-free mice implicate a role for the microbiota in programming barrier generation, but its natural ontogeny remains undefined. We now investigate the mucus barrier and sentinel goblet cell development in relation to postnatal colonization. Combined in vivo and ex vivo analyses demonstrate rapid and sequential microbiota-dependent development of these primary and secondary goblet cell protective functions, with dynamic changes in mucus processing dependent on innate immune signaling via MyD88 and development of functional sentinel goblet cells dependent on the NADPH/dual oxidase family member Duox2. Our findings identify new mechanisms of microbiota-goblet cell regulatory interaction and highlight the critical importance of the pre-weaning period for the normal development of protective systems that are key legislators of host-microbiota interaction.

Pretransplant targeting of TNFRSF25 and CD25 stimulates recipient Tregs in target tissues ameliorating GVHD post-HSCT

The current approach to minimize transplant-associated complications, including graft-versus-host disease (GVHD) includes long-term pharmacological immune suppression frequently accompanied by unwanted side effects. Advances in targeted immunotherapies regulating alloantigen responses in the recipient continue to reduce the need for pan-immunosuppression. Here, in vivo targeting of the TNF superfamily receptor 25 (TNFRSF25) and the high affinity IL-2 receptor with a TL1A-Ig fusion protein and low dose IL-2, respectively, was used to pretreat recipient mice prior to allogeneic-HSCT (aHSCT). Pretreatment induced Treg expansion persisting early post-aHSCT leading to diminished GVHD and improved transplant outcomes. Expansion was accompanied by an increase in frequency of stable and functionally active Tregs as evidenced by in vitro assays using cells from major GVHD target tissues including colon, liver, and eye. Importantly, pretreatment supported epithelial cell function/integrity, a diverse microbiome including reduction of pathologic bacteria overgrowth and promotion of butyrate producing bacteria, while maintaining physiologic levels of obligate/facultative anaerobes. Notably, using a sphingosine 1-phosphate receptor agonist to sequester T cells in lymphoid tissues, we found that the increased tissue Treg frequency included resident CD69 + CD103 + FoxP3 + hepatic Tregs. In contrast to infusion of donor Treg cells, the strategy developed here resulted in the presence of immunosuppressive target tissue environments in the recipient prior to the receipt of donor allo-reactive T cells and successful perseveration of GVL responses. We posit strategies that circumvent the need of producing large numbers of ex-vivo manipulated Tregs, may be accomplished through in vivo recipient Treg expansion, providing translational approaches to improve aHSCT outcomes.

Delving the depths of 'terra incognita' in the human intestine - the small intestinal microbiota

The small intestinal microbiota has a crucial role in gastrointestinal health, affecting digestion, immune function, bile acid homeostasis and nutrient metabolism. The challenges of accessibility at this site mean that our knowledge of the small intestinal microbiota is less developed than of the colonic or faecal microbiota. Here, we summarize the features and fluctuations of the microbiota along the small intestinal tract, focusing on humans, and discuss physicochemical factors and assessment methods, including the technical challenges of investigating the low microbial biomass of the proximal small bowel. We highlight the essential protective mechanisms of the small intestine, including motility, the paracellular barrier and mucus, and secretory immunity, to show their roles in limiting excessive exposure of host tissues to microbial metabolites. We address current knowledge gaps, particularly the variability among individuals, the effects of dysbiosis of the small intestinal microbiota on health and how different taxa in small intestinal microbiota could compensate for each other functionally.

Comprehensive analysis of heterogeneity and cell-cell interactions in Crohn's disease reveals novel location-specific insights

INTRODUCTION

In Crohn's disease (CD), lesions are mainly distributed in a segmental manner, with the primary sites of involvement being the ileum and colon. Heterogeneity in colon and ileum results in location-specific clinical presentations and therapeutic responses. Mucosal healing tends to be more readily and quickly achieved in the colon than in the ileum, where lesions are more likely to develop into complex behaviors. The heterogeneity of colon and ileum in CD, which is essential for tailored therapeutic approaches, has not yet been systematically illustrated.

OBJECTIVES

CD presents with unique intestinal lesions, mainly impacting the terminal ileum and colon. It is essential to comprehend the diversity in pathogenesis and treatment response among various segments.

METHODS

We conducted comparative single-cell RNA sequencing analysis in treatment-naïve CD patients, concentrating on the colon and ileum.

RESULTS

A novel subset of epithelial cells expressing high levels of DUOX2 and DUOXA2 (DUOX2-epi) was discovered. This DUOX2-epi subcluster predominantly distributed in the tip epithelium of the inflamed colon, potentially in response to microbial infection, as evidenced by the significant enrichment of inflammatory and microbial response pathways. The colonic and ileal DUOX2-epi subsets trigger inflammatory responses through distinct mechanisms. The colonic DUOX2-epi primarily affects monocytes via the SAA1-FPR2 ligand-receptor interaction, whereas the ileal DUOX2-epi directly interacts with regulate T cells through the CXCL16-CXCR6 ligand-receptor pair. Moreover, the cell-cell communication networks involving DUOX2-epi in the colon and ileum can help predict the location-specific effects of biological therapies.

CONCLUSION

This study delves into the heterogeneity within the ileum and colon of Crohn's disease at the single-cell level, identifying a new epithelial subset DUOX2-epi. Predictive gene modules tailored to different locations for biological therapies are developed as well, based on the cell-cell communication network modulated by DUOX2-epi.

Dysregulated NOX1-NOS2 activity as hallmark of ileitis in mice

Inflammation of the ileum, or ileitis, is commonly caused by Crohn's disease (CD) but can also accompany ulcerative colitis (backwash ileitis), infections or drug-related damage. Oxidative tissue injury triggered by reactive oxygen species (ROS) is considered part of the ileitis etiology. However, not only elevated ROS but also permanently decreased ROS are associated with inflammatory bowel disease (IBD). While very early onset IBD (VEO-IBD) is associated with a spectrum of NOX1 variants, how NOX1 inactivation contributes to disease development remains ill-defined. Besides propagating signaling responses, NOX1 provides superoxide for peroxynitrite formation in the epithelial barrier. Here we report that NOX4, an H2O2-generating NADPH oxidase with documented tissue protective effects in the intestine and other tissues, limits the generation of ileal peroxynitrite by NOX1/NOS2. Deletion of NOX4 leads to persistent peroxynitrite excess, hyperpermeability, villus blunting, muscular hypertrophy, chemokine/cytokine upregulation and dysbiosis. Conversely, SAMP1/YitFc mice, a CD-like ileitis model, showed age-dependent NOX1/NOS2 downregulation preventing ileal peroxynitrite formation in homeostasis and LPS-induced acute inflammation. Deficiency in NOX1 correlated with the upregulation of antimicrobial peptides, suggesting that ileal peroxynitrite acts as chemical barrier and microbiota modifier in the ileum.

Neonatal microbiota colonization drives maturation of primary and secondary goblet cell mediated protection in the pre-weaning colon

In the distal colon, mucus secreting goblet cells primarily confer protection from luminal microorganisms via generation of a sterile inner mucus layer barrier structure. Bacteria-sensing sentinel goblet cells provide a secondary defensive mechanism that orchestrates mucus secretion in response to microbes that breach the mucus barrier. Previous reports have identified mucus barrier deficiencies in adult germ-free mice, thus implicating a fundamental role for the microbiota in programming mucus barrier generation. In this study, we have investigated the natural neonatal development of the mucus barrier and sentinel goblet cell-dependent secretory responses upon postnatal colonization. Combined in vivo and ex vivo analyses of pre- and post-weaning colonic mucus barrier and sentinel goblet cell maturation demonstrated a sequential microbiota-dependent development of these primary and secondary goblet cell-intrinsic protective functions, with dynamic changes in mucus processing dependent on innate immune signalling via MyD88, and development of functional sentinel goblet cells dependent on the NADPH/Dual oxidase family member Duox2. Our findings therefore identify new mechanisms of microbiota-goblet cell regulatory interaction and highlight the critical importance of the pre-weaning period for the normal development of colonic barrier function.

Proteomic Differences in Colonic Epithelial Cells in Ulcerative Colitis Have an Epigenetic Basis

Background and Aims

The colonic epithelium serves as both a barrier to lumenal contents and a gatekeeper of inflammatory responses. In ulcerative colitis (UC), epithelial dysfunction is a core feature, but little is known about the cellular changes that may underlie disease pathology. We therefore evaluated how the chromatin epigenetics and proteome of epithelial cells differs between health and UC.

Methods

We sorted live CD326+ epithelial cells from colon biopsies of healthy control (HC) screening colonoscopy recipients and from inflamed or uninflamed colon segments of UC patients on no biologic nor immunomodulator therapy (n = 5-7 subjects per group). Cell lysates were analyzed by proteomic evaluation and nuclei were analyzed for open chromatin with assay for transposase-accessible chromatin using sequencing.

Results

Proteins most highly elevated in inflamed UC biopsies relative to HC were those encoded by the HLA-DRA (P = 3.1 × 10-33) and CD74 (P = 1.6 × 10-27), genes associated with antigen presentation, and the antimicrobial dual oxidase 2 (DUOX2) (P = 3.2 × 10-28) and lipocalin-2 (P = 2.2 × 10-26) genes. Conversely, the water channel aquaporin 8 was strikingly less common with inflammation (P = 1.9 × 10-18). Assay for transposase-accessible chromatin using sequencing revealed more open chromatin around the aquaporin 8 gene in HCs (P = 2.0 × 10-2) and more around the DUOX2/DUOXA2 locus in inflamed UC colon (P = 5.7 × 10-4), suggesting an epigenetic basis for differential protein expression by epithelial cells in health and disease.

Conclusion

Numerous differences exist between the proteome and chromatin of colonic epithelial cells in UC patients and HCs, some of which correlate to suggest specific epigenetic mechanisms regulating the epithelial proteome.

Roles of airway and intestinal epithelia in responding to pathogens and maintaining tissue homeostasis

Epithelial cells form a resilient barrier and orchestrate defensive and reparative mechanisms to maintain tissue stability. This review focuses on gut and airway epithelia, which are positioned where the body interfaces with the outside world. We review the many signaling pathways and mechanisms by which epithelial cells at the interface respond to invading pathogens to mount an innate immune response and initiate adaptive immunity and communicate with other cells, including resident microbiota, to heal damaged tissue and maintain homeostasis. We compare and contrast how airway and gut epithelial cells detect pathogens, release antimicrobial effectors, collaborate with macrophages, Tregs and epithelial stem cells to mount an immune response and orchestrate tissue repair. We also describe advanced research models for studying epithelial communication and behaviors during inflammation, tissue injury and disease.

Genetic and microbial determinants of azoxymethane-induced colorectal tumor susceptibility in Collaborative Cross mice and their implication in human cancer

The insights into interactions between host genetics and gut microbiome (GM) in colorectal tumor susceptibility (CTS) remains lacking. We used Collaborative Cross mouse population model to identify genetic and microbial determinants of Azoxymethane-induced CTS. We identified 4417 CTS-associated single nucleotide polymorphisms (SNPs) containing 334 genes that were transcriptionally altered in human colorectal cancers (CRCs) and consistently clustered independent human CRC cohorts into two subgroups with different prognosis. We discovered a set of genera in early-life associated with CTS and defined a 16-genus signature that accurately predicted CTS, the majority of which were correlated with human CRCs. We identified 547 SNPs associated with abundances of these genera. Mediation analysis revealed GM as mediators partially exerting the effect of SNP UNC3869242 within Duox2 on CTS. Intestine cell-specific depletion of Duox2 altered GM composition and contribution of Duox2 depletion to CTS was significantly influenced by GM. Our findings provide potential novel targets for personalized CRC prevention and treatment.

Epithelial Dual Oxidase 2 Shapes the Mucosal Microbiome and Contributes to Inflammatory Susceptibility

Reactive oxygen species (ROS) are highly reactive molecules formed from diatomic oxygen. They act as cellular signals, exert antibiotic activity towards invading microorganisms, but can also damage host cells. Dual oxidase 2 (DUOX2) is the main ROS-producing enzyme in the intestine, regulated by cues of the commensal microbiota and functions in pathogen defense. DUOX2 plays multiple roles in different organs and cell types, complicating the functional analysis using systemic deletion models. Here, we interrogate the precise role of epithelial DUOX2 for intestinal homeostasis and host-microbiome interactions. Conditional Duox2∆IEC mice lacking DUOX2, specifically in intestinal epithelial cells, were generated, and their intestinal mucosal immune phenotype and microbiome were analyzed. Inflammatory susceptibility was evaluated by challenging Duox2∆IEC mice in the dextran sodium sulfate (DSS) colitis model. DUOX2-microbiome interactions in humans were investigated by paired analyses of mucosal DUOX2 expression and fecal microbiome data in patients with intestinal inflammation. Under unchallenged conditions, we did not observe any obvious phenotype of Duox2∆IEC mice, although intestinal epithelial ROS production was drastically decreased, and the mucosal microbiome composition was altered. When challenged with DSS, Duox2∆IEC mice were protected from colitis, possibly by inhibiting ROS-mediated damage and fostering epithelial regenerative responses. Finally, in patients with intestinal inflammation, DUOX2 expression was increased in inflamed tissue, and high DUOX2 levels were linked to a dysbiotic microbiome. Our findings demonstrate that bidirectional DUOX2-microbiome interactions contribute to mucosal homeostasis, and their dysregulation may drive disease development, thus highlighting this axis as a therapeutic target to treat intestinal inflammation.

Duox mediated ROS production inhibited WSSV replication in Eriocheir sinensis under short-term nitrite stress

Nitrite stress and white spot syndrome virus (WSSV) infection are major problems threatening the sustainable and healthy development of Eriocheir sinensis. Some studies have found that nitrite stress can lead to the production of reactive oxygen species (ROS), whereas synthetic ROS plays a vital role in the signaling pathway. However, whether nitrite stress influences the infection of crabs by WSSV remains unclear. NADPH oxidases, including NOX1-5 and Duox1-2, are important for ROS production. In the present study, a novel Duox gene (designated as EsDuox) was identified from E. sinensis. The studies found that nitrite stress could increase the expression of EsDuox during WSSV infection and decrease the transcription of the WSSV envelope protein VP28. Moreover, nitrite stress could increase the production of ROS, and the synthesis of ROS relied on EsDuox. These results indicated a potential "nitrite stress-Duox activation-ROS production" pathway that plays a negative role in WSSV infection in E. sinensis. Further studies found that nitrite stress and EsDuox could promote the expression of EsDorsal transcriptional factor and antimicrobial peptides (AMPs) during WSSV infection. Moreover, the synthesis of AMPs was positively regulated by EsDorsal in the process of WSSV infection under nitrite stress. Furthermore, EsDorsal played an inhibitory role in the replication of WSSV under nitrite stress. Our study reveals a new pathway for "nitrite stress-Duox activation-ROS production-Dorsal activation-AMP synthesis" that is involved in the defense against WSSV infection in E. sinensis during short-term nitrite stress.

Algal oil alleviates antibiotic-induced intestinal inflammation by regulating gut microbiota and repairing intestinal barrier

Introduction

Taking antibiotics would interfere with gut microbiota and increase the risk of opportunistic pathogen infection and inflammation.

Methods

In this study, 36 male C57BL/6 mice were divided into 4 groups (n = 9) to investigate whether two kinds of algal oil could alleviate the intestinal damage induced by CS (Ceftriaxone sodium). These algal oils were obtained from Schizochytrium sp. cultures using Yeast extract (YE) and Rapeseed meal (RSM) as substrate, respectively. All tested mice were administrated with CS for 8 days and then the colon pathological morphology, the expression levels of inflammatory factors and the gut microbial profile were analyzed in mice supplemented with or without algal oil.

Results

The results showed that both YE and RSM algal oils markedly reduced mucosal damage and intestinal inflammatory response in CS-treated mice by inhibiting the pro-inflammatory cytokine tumor necrosis factor (TNF)-α, interleukin (IL)-6 and myeloperoxidase (MPO) activity. In addition, fluorescence immunohistochemistry showed that the tight junction protein ZO-1 was increased in mice supplemented with YE and RSM algal oil. Furthermore, YE algal oil promoted the beneficial intestinal bacteria such as Lachnospiraceae and S24_7 compared with the CS group, while supplementation with RSM algal oil enriched the Robinsoniella. Spearman's correlation analysis exhibited that Melissococcus and Parabacteroides were positively correlated with IL-6 but negatively correlated with IL-10.

Discussion

This study suggested that supplementation with algal oil could alleviate intestinal inflammation by regulating gut microbiota and had a protective effect on maintaining intestinal barrier against antibiotic-induced damage in mice.

Evolutionary aspects of gastrointestinal tract microbiome-host interaction underlying gastrointestinal barrier integrity

In the host sustenance and homeostasis, the microbiome is a key component in the functional system. Throughout ontogenetic development, microbiome including that of the gastrointestinal tract (GIT) is the vital factor that ensures not only host functioning, but also its interaction with environment. To uncover the mechanisms underlying GIT microbiome showing a decisive influence on host organism, a systematic approach is needed, because diverse microorganisms are predominantly localized in different parts of the GIT. Recently, a new interdisciplinary direction of science, nanobioinformatics that has been extensively developed considers gene networks as the major object of study representing a coordinated group of genes that functionally account for formation and phenotypic disclosure of various host traits. Here, an important place should be provided to the genetically determined level of the gastrointestinal tract microbiome, its interaction at the level of the host food systems. There have been increasing evidence indicating that the microbiome is directly involved in the pathogenesis of host diseases showing a multi-layered interaction with host metabolic and immune systems. At the same time, the microbial community is unevenly distributed throughout the gastrointestinal tract, and its different portions are variously active while interacting with the host immune system. The architecture of interaction between the microbiome and host cells is extremely complex, and the interaction of individual cells, at the same time, varies greatly. Bacteria colonizing the crypts of the small intestine regulate enterocyte proliferation by affecting DNA replication and gene expression, while bacteria at the tip of the intestinal villi mediate gene expression responsible for metabolism and immune response. Enterocytes and Paneth cells, in turn, regulate the vital activity of the community of microorganisms through the production of polysaccharides (carbohydrates) and antibacterial factors on their surface. Thus, the integrity of the gastrointestinal barrier (GIB) is maintained, which protects the body from infections and inflammation, while violation of its integrity leads to a number of diseases. It has been shown that depending on the dominance of certain types of bacteria the microbiome can maintain or disrupt GIB integrity. The structural and functional GIB integrity is important for body homeostasis. To date, at least 50 proteins have been characterized as being involved in the structural and functional integrability of tight junctions between gastrointestinal tract epithelial cells. The current review comprehensively discusses such issues and presents original research carried out at various facilities of translational biomedicine.

Heart failure and cancer: From active exposure to passive adaption

The human body seems like a "balance integrator." On the one hand, the body constantly actively receives various outside stimuli and signals to induce changes. On the other hand, several internal regulations would be initiated to adapt to these changes. In most cases, the body could keep the balance in vitro and in vivo to reach a healthy body. However, in some cases, the body can only get to a pathological balance. Actively exposed to unhealthy lifestyles and passively adapting to individual primary diseases lead to a similarly inner environment for both heart failure and cancer. To cope with these stimuli, the body must activate the system regulation mechanism and face the mutual interference. This review summarized the association between heart failure and cancer from active exposure to passive adaption. Moreover, we hope to inspire researchers to contemplate these two diseases from the angle of overall body consideration.

Role of Reactive Oxygen Species in Aging and Age-Related Diseases: A Review

Research on the role of reactive oxygen species (ROS) in the aging process has advanced significantly over the last two decades. In light of recent findings, ROS takes part in the aging process of cells along with contributing to various physiological signaling pathways. Antioxidants being cells' natural defense mechanism against ROS-mediated alteration, play an imperative role to maintain intracellular ROS homeostasis. Although the complete understanding of the ROS regulated aging process is yet to be fully comprehended, current insights into various sources of cellular ROS and their correlation with the aging process and age-related diseases are portrayed in this review. In addition, results on the effect of antioxidants on ROS homeostasis and the aging process as well as their advances in clinical trials are also discussed in detail. The future perspective in ROS-antioxidant dynamics on antiaging research is also marshaled to provide future directions for ROS-mediated antiaging research fields.

The phenotype of the gut region is more stably retained than developmental stage in piglet intestinal organoids

Intestinal organoids are innovative in vitro tools to study the digestive epithelium. The objective of this study was to generate jejunum and colon organoids from suckling and weaned piglets in order to determine the extent to which organoids retain a location-specific and a developmental stage-specific phenotype. Organoids were studied at three time points by gene expression profiling for comparison with the transcriptomic patterns observed in crypts in vivo. In addition, the gut microbiota and the metabolome were analyzed to characterize the luminal environment of epithelial cells at the origin of organoids. The location-specific expression of 60 genes differentially expressed between jejunum and colon crypts from suckling piglets was partially retained (48%) in the derived organoids at all time point. The regional expression of these genes was independent of luminal signals since the major differences in microbiota and metabolome observed in vivo between the jejunum and the colon were not reproduced in vitro. In contrast, the regional expression of other genes was erased in organoids. Moreover, the developmental stage-specific expression of 30 genes differentially expressed between the jejunum crypts of suckling and weaned piglets was not stably retained in the derived organoids. Differentiation of organoids was necessary to observe the regional expression of certain genes while it was not sufficient to reproduce developmental stage-specific expression patterns. In conclusion, piglet intestinal organoids retained a location-specific phenotype while the characteristics of developmental stage were erased in vitro. Reproducing more closely the luminal environment might help to increase the physiological relevance of intestinal organoids.

Increased NOX1 and DUOX2 expression in the colonic mucosa of patients with chronic functional constipation

To determine whether oxidative stress and inflammation are associated with constipation by examining the expression of the main producers of reactive oxygen species, nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, and pro-inflammatory cytokines in the colon of patients with chronic functional constipation. The colonic biopsies were collected from 32 patients with chronic functional constipation and 30 healthy subjects who underwent colonoscopy. Colonic mucosal histology was observed. Interleukin (IL)-1β, IL-6, IL-8 messenger RNA (mRNA), and 4 members of NADPH oxidase (NOX1, NOX2, DUOX2, and NOX4) protein and mRNA were assessed by immunohistochemistry, western blotting, and reverse transcription polymerase chain reaction. The tissues from both patients and healthy subjects showed normal histological structure without increase of inflammatory cells. NOX1 protein and mRNA levels were significantly increased compared to controls (P < .05). DUOX2 protein, but not mRNA, was increased by 2-fold compared to controls (P < .05). The levels of NOX2 and NOX4 protein and mRNA demonstrated no significant difference between patients and control subjects. The levels of IL-1β and IL-6 mRNA were significantly higher in constipation patients (P < .05), while IL-8 mRNA level was no different between the 2 groups. NADPH oxidase and pro-inflammatory cytokine might be involved in the pathogeneses of chronic functional constipation.

Psychological stress disrupts intestinal epithelial cell function and mucosal integrity through microbe and host-directed processes

Psychological stress alters the gut microbiota and predisposes individuals to increased risk for enteric infections and chronic bowel conditions. Intestinal epithelial cells (IECs) are responsible for maintaining homeostatic interactions between the gut microbiota and its host. In this study, we hypothesized that disruption to colonic IECs is a key factor underlying stress-induced disturbances to intestinal homeostasis. Conventionally raised (CONV-R) and germ-free (GF) mice were exposed to a social disruption stressor (Str) to ascertain how stress modifies colonic IECs, the mucosal layer, and the gut microbiota. RNA sequencing of IECs isolated from CONV-R mice revealed a robust pro-inflammatory (Saa1, Il18), pro-oxidative (Duox2, Nos2), and antimicrobial (Reg3b/g) transcriptional profile as a result of Str. This response occurred concomitant to mucus layer thinning and signs of microbial translocation. In contrast to their CONV-R counterparts, IECs from GF mice or mice treated with broad spectrum antibiotics exhibited no detectable transcriptional changes in response to Str. Nevertheless, IECs from Str-exposed GF mice exhibited an altered response to ex vivo bacterial challenge (increased dual Oxidase-2 [Duox2] and nitric oxide synthase-2 (Nos2)), indicating that STR primes host IEC pro-oxidative responses. In CONV-R mice stress-induced increases in colonic Duox2 and Nos2 (ROS generating enzymes) strongly paralleled changes to microbiome composition and function, evidencing Str-mediated ROS production as a primary factor mediating gut-microbiota dysbiosis. In conclusion, a mouse model of social stress disrupts colonic epithelial and mucosal integrity, a response dependent on an intact microbiota and host stress signals. Together these preclinical findings may provide new insight into mechanisms of stress-associated bowel pathologies in humans.

Microbiome in cancer: Role in carcinogenesis and impact in therapeutic strategies

Cancer is the world's second-leading cause of death, and the involvement of microbes in a range of diseases, including cancer, is well established. The gut microbiota is known to play an important role in the host's health and physiology. The gut microbiota and its metabolites may activate immunological and cellular pathways that kill invading pathogens and initiate a cancer-fighting immune response. Cancer is a multiplex illness, characterized by the persistence of several genetic and physiological anomalies in malignant tissue, complicating disease therapy and control. Humans have coevolved with a complex bacterial, fungal, and viral microbiome over millions of years. Specific long-known epidemiological links between certain bacteria and cancer have recently been grasped at the molecular level. Similarly, advances in next-generation sequencing technology have enabled detailed research of microbiomes, such as the human gut microbiome, allowing for the finding of taxonomic and metabolomic linkages between the microbiome and cancer. These investigations have found causative pathways for both microorganisms within tumors and bacteria in various host habitats far from tumors using direct and immunological procedures. Anticancer diagnostic and therapeutic solutions could be developed using this review to tackle the threat of anti-cancer medication resistance as well through the wide-ranging involvement of the microbiota in regulating host metabolic and immunological homeostasis. We reviewed the significance of gut microbiota in cancer initiation as well as cancer prevention. We look at certain microorganisms that may play a role in the development of cancer. Several bacteria with probiotic qualities may be employed as bio-therapeutic agents to re-establish the microbial population and trigger a strong immune response to remove malignancies, and further study into this should be conducted.

Microbiota-Associated Biofilm Regulation Leads to Vibrio cholerae Resistance Against Intestinal Environmental Stress

The commensal microbes of the gut microbiota make important contributions to host defense against gastrointestinal pathogens, including Vibrio cholerae, the etiologic agent of cholera. As interindividual microbiota variation drives individual differences in infection susceptibility, we examined both host and V. cholerae gene expression during infection of suckling mice transplanted with different model human commensal communities, including an infection-susceptible configuration representing communities damaged by recurrent diarrhea and malnutrition in cholera endemic areas and a representative infection-resistant microbiota characteristic of healthy individuals. In comparison to colonization of animals with resistant microbiota, animals bearing susceptible microbiota challenged with V. cholerae downregulate genes associated with generation of reactive oxygen/nitrogen stress, while V. cholerae in these animals upregulates biofilm-associated genes. We show that V. cholerae in susceptible microbe infection contexts are more resistant to oxidative stress and inhibitory bile metabolites generated by the action of commensal microbes and that both phenotypes are dependent on biofilm-associated genes, including vpsL. We also show that susceptible and infection-resistant microbes drive different bile acid compositions in vivo by the action of bile salt hydrolase enzymes. Taken together, these findings provide a better understanding of how the microbiota uses multiple mechanisms to modulate the infection-associated host environment encountered by V. cholerae, leading to commensal-dependent differences in infection susceptibility.

Effects of Shrimp Peptide Hydrolysate on Intestinal Microbiota Restoration and Immune Modulation in Cyclophosphamide-Treated Mice

The gut microbiota is important in regulating host metabolism, maintaining physiology, and protecting immune homeostasis. Gut microbiota dysbiosis affects the development of the gut microenvironment, as well as the onset of various external systemic diseases and metabolic syndromes. Cyclophosphamide (CTX) is a commonly used chemotherapeutic drug that suppresses the host immune system, intestinal mucosa inflammation, and dysbiosis of the intestinal flora. Immunomodulators are necessary to enhance the immune system and prevent homeostasis disbalance and cytotoxicity caused by CTX. In this study, shrimp peptide hydrolysate (SPH) was evaluated for immunomodulation, intestinal integration, and microbiota in CTX-induced immunosuppressed mice. It was observed that SPH would significantly restore goblet cells and intestinal mucosa integrity, modulate the immune system, and increase relative expression of mRNA and tight-junction associated proteins (Occludin, Zo-1, Claudin-1, and Mucin-2). It also improved gut flora and restored the intestinal microbiota ecological balance by removing harmful microbes of various taxonomic groups. This would also increase the immune organs index, serum levels of cytokines (IFN-ϒ, IL1β, TNF-α, IL-6), and immunoglobin levels (IgA, IgM). The Firmicutes/Bacteroidetes proportion was decreased in CTX-induced mice. Finally, SPH would be recommended as a functional food source with a modulatory effect not only on intestinal microbiota, but also as a potential health-promoting immune function regulator.

Pollutants enhance IgE sensitization in the gut via local alteration of vitamin D-metabolizing enzymes

Mechanisms linking ingested pollutants to increased incidence of allergy are poorly understood. We report that mice exposed to low doses of cadmium develop higher IgE responses following oral allergen sensitization and more severe allergic symptoms upon allergen challenge. The environmentally relevant doses of this pollutant also induced oxidative/inflammatory responses in the gut of SPF, but not germ-free mice. Interestingly, the increased IgE responses correlated with stimulation of the vitamin D3-metabolizing enzymes CYP27B1 and CYP24A1 in the gut and increased luminal levels of oxidized vitamin D3 metabolites that are not ligands of the vitamin D receptor. Inhibition of CYP27B1 and CYP24A1 via oral administration of pharmacological inhibitors reduced IgE responses induced in mice orally exposed to cadmium. Our findings identify local alteration of vitamin D signaling as a new mechanism for induction of IgE responses by environmental pollutants. They also identify vitamin D3-metabolizing enzymes as therapeutic targets for the treatment of allergy.

The role of NADPH oxidases in infectious and inflammatory diseases

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOX) are enzymes that generate superoxide or hydrogen peroxide from molecular oxygen utilizing NADPH as an electron donor. There are seven enzymes in the NOX family: NOX1-5 and dual oxidase (DUOX) 1-2. NOX enzymes in humans play important roles in diverse biological functions and vary in expression from tissue to tissue. Importantly, NOX2 is involved in regulating many aspects of innate and adaptive immunity, including regulation of type I interferons, the inflammasome, phagocytosis, antigen processing and presentation, and cell signaling. DUOX1 and DUOX2 play important roles in innate immune defenses at epithelial barriers. This review discusses the role of NOX enzymes in normal physiological processes as well as in disease. NOX enzymes are important in autoimmune diseases like type 1 diabetes and have also been implicated in acute lung injury caused by infection with SARS-CoV-2. Targeting NOX enzymes directly or through scavenging free radicals may be useful therapies for autoimmunity and acute lung injury where oxidative stress contributes to pathology.

A single nucleotide mutation in the dual-oxidase 2 (DUOX2) gene causes some of the panda's unique metabolic phenotypes

The giant panda (Ailuropoda melanoleuca) is an iconic bear native to China, famous for eating almost exclusively bamboo. This unusual dietary behavior for a carnivore is enabled by several key adaptations including low physical activity, reduced organ sizes and hypothyroidism leading to lowered energy expenditure. These adaptive phenotypes have been hypothesized to arise from a panda-unique single-nucleotide mutation in the dual-oxidase 2 (DUOX2) gene, involved in thyroid hormone synthesis. To test this hypothesis, we created genome-edited mice carrying the same point mutation as the panda and investigated its effect on metabolic phenotype. Homozygous mice were 27% smaller than heterozygous and wild-type ones, had 13% lower body mass-adjusted food intake, 55% decreased physical activity, lower mass of kidneys (11%) and brain (5%), lower serum thyroxine (T4: 36%), decreased absolute (12%) and mass-adjusted (5%) daily energy expenditure, and altered gut microbiota. Supplementation with T4 reversed the effects of the mutation. This work uses a state-of-the-art genome editing approach to demonstrate the link between a single-nucleotide mutation in a key endocrine-related gene and profound adaptive changes in the metabolic phenotype, with great importance in ecology and evolution.

The plant NADPH oxidase RBOHD is required for microbiota homeostasis in leaves

The plant microbiota consists of a multitude of microorganisms that can affect plant health and fitness. However, it is currently unclear how the plant shapes its leaf microbiota and what role the plant immune system plays in this process. Here, we evaluated Arabidopsis thaliana mutants with defects in different parts of the immune system for an altered bacterial community assembly using a gnotobiotic system. While higher-order mutants in receptors that recognize microbial features and in defence hormone signalling showed substantial microbial community alterations, the absence of the plant NADPH oxidase RBOHD caused the most pronounced change in the composition of the leaf microbiota. The rbohD knockout resulted in an enrichment of specific bacteria. Among these, we identified Xanthomonas strains as opportunistic pathogens that colonized wild-type plants asymptomatically but caused disease in rbohD knockout plants. Strain dropout experiments revealed that the lack of RBOHD unlocks the pathogenicity of individual microbiota members driving dysbiosis in rbohD knockout plants. For full protection, healthy plants require both a functional immune system and a microbial community. Our results show that the NADPH oxidase RBOHD is essential for microbiota homeostasis and emphasizes the importance of the plant immune system in controlling the leaf microbiota.

Raising the 'Good' Oxidants for Immune Protection

Redox medicine is a new therapeutic concept targeting reactive oxygen species (ROS) and secondary reaction products for health benefit. The concomitant function of ROS as intracellular second messengers and extracellular mediators governing physiological redox signaling, and as damaging radicals instigating or perpetuating various pathophysiological conditions will require selective strategies for therapeutic intervention. In addition, the reactivity and quantity of the oxidant species generated, its source and cellular location in a defined disease context need to be considered to achieve the desired outcome. In inflammatory diseases associated with oxidative damage and tissue injury, ROS source specific inhibitors may provide more benefit than generalized removal of ROS. Contemporary approaches in immunity will also include the preservation or even elevation of certain oxygen metabolites to restore or improve ROS driven physiological functions including more effective redox signaling and cell-microenvironment communication, and to induce mucosal barrier integrity, eubiosis and repair processes. Increasing oxidants by host-directed immunomodulation or by exogenous supplementation seems especially promising for improving host defense. Here, we summarize examples of beneficial ROS in immune homeostasis, infection, and acute inflammatory disease, and address emerging therapeutic strategies for ROS augmentation to induce and strengthen protective host immunity.

NOX1-dependent redox signaling potentiates colonic stem cell proliferation to adapt to the intestinal microbiota by linking EGFR and TLR activation

The colon epithelium is a primary point of interaction with the microbiome and is regenerated by a few rapidly cycling colonic stem cells (CSCs). CSC self-renewal and proliferation are regulated by growth factors and the presence of bacteria. However, the molecular link connecting the diverse inputs that maintain CSC homeostasis remains largely unknown. We report that CSC proliferation is mediated by redox-dependent activation of epidermal growth factor receptor (EGFR) signaling via NADPH oxidase 1 (NOX1). NOX1 expression is CSC specific and is restricted to proliferative CSCs. In the absence of NOX1, CSCs fail to generate ROS and have a reduced proliferation rate. NOX1 expression is regulated by Toll-like receptor activation in response to the microbiota and serves to link CSC proliferation with the presence of bacterial components in the crypt. The TLR-NOX1-EGFR axis is therefore a critical redox signaling node in CSCs facilitating the quiescent-proliferation transition and responds to the microbiome to maintain colon homeostasis.

Intestinal IL-17R Signaling Controls Secretory IgA and Oxidase Balance in Citrobacter rodentium Infection

Type 17 cytokines have been strongly implicated in mucosal immunity, in part by regulating the production of antimicrobial peptides. Using a mouse model of Citrobacter rodentium infection, which causes colitis, we found that intestinal IL-17RA and IL-17RC were partially required for control of infection in the colon and IL-17 regulates the production of luminal hydrogen peroxide as well as expression of Tnsf13 Reduced Tnfsf13 expression was associated with a profound defect in generating C. rodentium-specific IgA⁺ Ab-secreting cells. Taken together, intestinal IL-17R signaling plays key roles in controlling invading pathogens, in part by regulating luminal hydrogen peroxide as well as regulating the generation of pathogen-specific IgA⁺ Ab-secreting cells.

In Vivo Transcriptome of Lactobacillus acidophilus and Colonization Impact on Murine Host Intestinal Gene Expression

Lactobacillus acidophilus NCFM is a probiotic strain commonly used in dairy products and dietary supplements. Postgenome in vitro studies of NCFM thus far have linked potential key genotypes to its probiotic-relevant attributes, including gut survival, prebiotic utilization, host interactions, and immunomodulatory activities. To corroborate and extend beyond previous in vivo and in vitro functional studies, we employed a dual RNA sequencing (RNA-seq) transcriptomic approach to identify genes potentially driving the gut fitness and activities of L. acidophilus NCFM in vivo, and in parallel, examine the ileal transcriptional response of its murine hosts during monocolonization. Spatial expression profiling of NCFM from the ileum through the colon revealed a set of 134 core genes that were consistently overexpressed during gut transit. These in vivo core genes are predominantly involved in the metabolism of carbohydrates, amino acids, and nucleotides, along with mucus-binding proteins and adhesion factors, confirming their functionally important roles in nutrient acquisition and gut retention. Functional characterization of the highly expressed major S-layer-encoding gene established its indispensable role as a cell shape determinant and maintenance of cell surface integrity, essential for viability and probiotic attributes. Host colonization by L. acidophilus resulted in significant downregulation of several proinflammatory cytokines and tight junction proteins. Genes related to redox signaling, mucin glycosylation, and circadian rhythm modulation were induced, suggesting impacts on intestinal development and immune functions. Metagenomic analysis of NCFM populations postcolonization demonstrated the genomic stability of L. acidophilus as a gut transient and further established its safety as a probiotic and biotherapeutic delivery platform.IMPORTANCE To date, our basis for comprehending the probiotic mechanisms of Lactobacillus acidophilus, one of the most widely consumed probiotic microbes, was largely limited to in vitro functional genomic studies. Using a germfree murine colonization model, in vivo-based transcriptional studies provided the first view of how L. acidophilus survives in the mammalian gut environment, including gene expression patterns linked to survival, efficient nutrient acquisition, stress adaptation, and host interactions. Examination of the host ileal transcriptional response, the primary effector site of L. acidophilus, has also shed light into the mechanistic roles of this probiotic microbe in promoting anti-inflammatory responses, maintaining intestinal epithelial homeostasis and modulation of the circadian-metabolic axis in its host.

Mini review: immunologic functions of dual oxidases in mucosal systems of vertebrates

Abstract Mucosal epithelial cells act as the first immunologic barrier of organisms, and contact directly with pathogens. Therefore, hosts must have differential strategies to combat pathogens efficiently. Reactive oxygen species (ROS), as a kind of oxidizing agents, participates in the early stage of killing pathogens quickly. Recent reports have revealed that dual oxidase (DUOX) plays a key role in mucosal immunity. And the DUOX is a transmembrane protein which produces ROS as their primary enzymatic products. This process is an important pattern for eliminating pathogens. In this review, we highlight the DUOX immunologic functions in the respiratory and digestive tract of vertebrates.

NOX2-Derived Reactive Oxygen Species in Cancer

The formation of reactive oxygen species (ROS) by the myeloid cell NADPH oxidase NOX2 is critical for the destruction of engulfed microorganisms. However, recent studies imply that ROS, formed by NOX2⁺ myeloid cells in the malignant microenvironment, exert multiple actions of relevance to the growth and spread of neoplastic cells. By generating ROS, tumor-infiltrating myeloid cells and NOX2⁺ leukemic myeloid cells may thus (i) compromise the function and viability of adjacent cytotoxic lymphocytes, including natural killer (NK) cells and T cells, (ii) oxidize DNA to trigger cancer-promoting somatic mutations, and (iii) affect the redox balance in cancer cells to control their proliferation and survival. Here, we discuss the impact of NOX2-derived ROS for tumorigenesis, tumor progression, regulation of antitumor immunity, and metastasis. We propose that NOX2 may be a targetable immune checkpoint in cancer.

Role of the microbiota in ileitis of a mouse model of inflammatory bowel disease-Glutathione peroxide isoenzymes 1 and 2-double knockout mice on a C57BL background

C57Bl6 (B6) mice devoid of glutathione peroxidases 1 and 2 (Gpx1/2-DKO) develop ileitis after weaning. We previously showed germ-free Gpx1/2-DKO mice of mixed B6.129 background did not develop ileocolitis. Here, we examine the composition of the ileitis provoking microbiota in B6 Gpx1/2-DKO mice. DNA was isolated from the ileum fecal stream and subjected to high-throughput sequencing of the V3 and V4 regions of the 16S rRNA gene to determine the abundance of operational taxonomic units (OTUs). We analyzed the role of bacteria by comparing the microbiomes of the DKO and pathology-free non-DKO mice. Mice were treated with metronidazole, streptomycin, and vancomycin to alter pathology and correlate the OTU abundances with pathology levels. Principal component analysis based on Jaccard distance of abundance showed 3 distinct outcomes relative to the source Gpx1/2-DKO microbiome. Association analyses of pathology and abundance of OTUs served to rule out 7-11 of 24 OTUs for involvement in the ileitis. Collections of OTUs were identified that appeared to be linked to ileitis in this animal model and would be classified as commensals. In Gpx1/2-DKO mice, host oxidant generation from NOX1 and DUOX2 in response to commensals may compromise the ileum epithelial barrier, a role generally ascribed to oxidants generated from mitochondria, NOX2 and endoplasmic reticulum stress in response to presumptive pathogens in IBD. Elevated oxidant levels may contribute to epithelial cell shedding, which is strongly associated with progress toward inflammation in Gpx1/2-DKO mice and predictive of relapse in IBD by allowing leakage of microbial components into the submucosa.

The Microbiome in Health and Disease from the Perspective of Modern Medicine and Ayurveda

The role of the microbiome in health and disease helps to provide a scientific understanding of key concepts in Ayurveda. We now recognize that virtually every aspect of our physiology and health is influenced by the collection of microorganisms that live in various parts of our body, especially the gut microbiome. There are many external factors which influence the composition of the gut microbiome but one of the most important is diet and digestion. Ayurveda and other systems of traditional health have for thousands of years focused on diet and digestion. Recent research has helped us understand the connection between the microbiome and the many different prevention and therapeutic treatment approaches of Ayurveda.

The Dual Role of Reactive Oxygen Species-Generating Nicotinamide Adenine Dinucleotide Phosphate Oxidases in Gastrointestinal Inflammation and Therapeutic Perspectives

Significance: Despite their intrinsic cytotoxic properties, mounting evidence indicates that reactive oxygen species (ROS) physiologically produced by the nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs) of epithelial cells (NOX1, dual oxidase [DUOX]2) and phagocytes (NOX2) are critical for innate immune response and homeostasis of the intestinal mucosa. However, dysregulated ROS production could be a driving factor in inflammatory bowel diseases (IBDs). Recent Advances: In addition to NOX2, recent studies have demonstrated that NOX1- and DUOX2-derived ROS can regulate intestinal innate immune defense and homeostasis by impacting many processes, including bacterial virulence, expression of bacteriostatic proteins, epithelial renewal and restitution, and microbiota composition. Moreover, the antibacterial role of DUOX2 is a function conserved in evolution as it has been described in invertebrates, and lower and higher vertebrates. In humans, variants of the NOX2, NOX1, and DUOX2 genes, which are associated with impaired ROS production, have been identified in very early onset IBD, but overexpression of NOX/DUOX, especially DUOX2, has also been described in IBD, suggesting that loss-of-function or excessive activity of the ROS-generating enzymes could contribute to disease progression. Critical Issues: Therapeutic perspectives aiming at targeting NOX/DUOX in IBD should take into account the two sides of NOX/DUOX-derived ROS in intestinal inflammation. Hence, NOX/DUOX inhibitors or ROS inducers should be considered as a function of the disease context. Future Directions: A thorough understanding of the physiological and pathological regulation of NOX/DUOX in the gastrointestinal tract is an absolute pre-requisite for the development of therapeutic strategies that can modulate ROS levels in space and time.

Fat-Shaped Microbiota Affects Lipid Metabolism, Liver Steatosis, and Intestinal Homeostasis in Mice Fed a Low-Protein Diet

SCOPE

Protein malnutrition is characterized by stunted growth, hepatic steatosis and a damaged gut mucosal architecture. Since high-fat shaped gut microbiota (HFM) has an increased ability in providing nutrients and energy from food to the host, the aim of this study is to determine whether such a microbiota could beneficially impact on the consequences of malnutrition.

METHODS AND RESULTS

The cecal content of specific pathogen free C57Bl/6J mice fed a high-fat diet or a low-protein diet is transplanted in two groups of germ-free C57Bl/6J recipient mice, which are subsequently fed a low-protein diet for 8 weeks. Body weight gain is comparable between the two groups of microbiota-recipient mice. The HFM led to a worsening of microvesicular steatosis and a decrease of plasma lipids compared to the low-protein shaped microbiota. In the small intestine of mice receiving the HFM, although significant histological differences are not observed, the expression of antimicrobial genes promoting oxidative stress and immune response at the ileal epithelium (Duox2, Duoxa2, Saa1, Ang4, Defa5) is increased.

CONCLUSION

The transplant of HFM in mice fed a low-protein diet represents a noxious stimulus for the ileal mucosa and impairs hepatic lipoprotein secretion, favoring the occurrence of hepatic microvesicular steatosis.

Investigation of Potential Genetic Biomarkers and Molecular Mechanism of Ulcerative Colitis Utilizing Bioinformatics Analysis

Objectives

To reveal the molecular mechanisms of ulcerative colitis (UC) and provide potential biomarkers for UC gene therapy.

Methods

We downloaded the GSE87473 microarray dataset from the Gene Expression Omnibus (GEO) and identified the differentially expressed genes (DEGs) between UC samples and normal samples. Then, a module partition analysis was performed based on a weighted gene coexpression network analysis (WGCNA), followed by pathway and functional enrichment analyses. Furthermore, we investigated the hub genes. At last, data validation was performed to ensure the reliability of the hub genes.

Results

Between the UC group and normal group, 988 DEGs were investigated. The DEGs were clustered into 5 modules using WGCNA. These DEGs were mainly enriched in functions such as the immune response, the inflammatory response, and chemotaxis, and they were mainly enriched in KEGG pathways such as the cytokine-cytokine receptor interaction, chemokine signaling pathway, and complement and coagulation cascades. The hub genes, including dual oxidase maturation factor 2 (DUOXA2), serum amyloid A (SAA) 1 and SAA2, TNFAIP3-interacting protein 3 (TNIP3), C-X-C motif chemokine (CXCL1), solute carrier family 6 member 14 (SLC6A14), and complement decay-accelerating factor (CD antigen CD55), were revealed as potential tissue biomarkers for UC diagnosis or treatment.

Conclusions

This study provides supportive evidence that DUOXA2, A-SAA, TNIP3, CXCL1, SLC6A14, and CD55 might be used as potential biomarkers for tissue biopsy of UC, especially SLC6A14 and DUOXA2, which may be new targets for UC gene therapy. Moreover, the DUOX2/DUOXA2 and CXCL1/CXCR2 pathways might play an important role in the progression of UC through the chemokine signaling pathway and inflammatory response.

Dexamethasone and Tofacitinib suppress NADPH oxidase expression and alleviate very-early-onset ileocolitis in mice deficient in GSH peroxidase 1 and 2

C57BL6/J (B6) mice lacking Se-dependent GSH peroxidase 1 and 2 (GPx1/2-DKO) develop mild to moderate ileocolitis around weaning. These DKO mice have a disease resembling human very-early-onset inflammatory bowel disease (VEOIBD), which is associated with mutations in NADPH oxidase genes. Drugs including dexamethasone (Dex), Tofacitinib (Tofa; a Janus kinase/JAK inhibitor) and anti-TNF antibody are effective to treat adult, but not pediatric IBD.

AIMS

To test the efficacy of hydrophobic Dex and hydrophilic Dex phosphate (Dex phos), Tofa, anti-Tnf Ab, Noxa1ds-TAT and gp91ds-TAT peptides (inhibiting NOX1 and NOX2 assembly respectively), antioxidant MJ33 and ML090, and pifithrin-α (p53 inhibitor) on alleviation of gut inflammation in DKO weanlings.

MAIN METHODS

All treatments began on 22-day-old GPx1/2-DKO mice. The mouse intestine pathology was compared between the drug- and vehicle-treated groups after six or thirteen days of treatment.

KEY FINDINGS

Among all drugs tested, Dex, Dex phos and Tofa were the strongest to suppress ileocolitis in the DKO weanlings. Dex, Dex phos and Tofa inhibited crypt apoptosis and increased crypt density. Dex or Dex phos alone also inhibited cell proliferation, exfoliation and crypt abscess in the ileum. Dex, but not Tofa, retarded mouse growth. Both Dex and Tofa inhibited ileum Nox1, Nox4 and Duox2, but not Nox2 gene expression. Noxa1ds-TAT and gp91ds-TAT peptides as well as MJ33 had subtle effect on suppressing pathology, while others had negligible effect.

SIGNIFICANCE

These findings suggest that NADPH oxidases can be novel drug targets for pediatric IBD therapy, and Tofa may be considered for treating VEOIBD.

Intestinal Epithelial Cells Respond to Chronic Inflammation and Dysbiosis by Synthesizing H2O2

The microbes in the gastrointestinal tract are separated from the host by a single layer of intestinal epithelial cells (IECs) that plays pivotal roles in maintaining homeostasis by absorbing nutrients and providing a physical and immunological barrier to potential pathogens. Preservation of homeostasis requires the crosstalk between the epithelium and the microbial environment. One epithelial-driven innate immune mechanism that participates in host-microbe communication involves the release of reactive oxygen species (ROS), such as hydrogen peroxide (H₂O₂), toward the lumen. Phagocytes produce high amounts of ROS which is critical for microbicidal functions; the functional contribution of epithelial ROS, however, has been hindered by the lack of methodologies to reliably quantify extracellular release of ROS. Here, we used a modified Amplex Red assay to investigate the inflammatory and microbial regulation of IEC-generated H₂O₂ and the potential role of Duox2, a NADPH oxidase that is an important source of H₂O₂. We found that colonoids respond to interferon-γ and flagellin by enhancing production of H₂O₂ in a Duox2-mediated fashion. To extend these findings, we analyzed ex vivo production of H₂O₂ by IECs after acute and chronic inflammation, as well as after exposure to dysbiotic microbiota. While acute inflammation did not induce a significant increase in epithelial-driven H₂O₂, chronic inflammation caused IECs to release higher levels of H₂O₂. Furthermore, colonization of germ-free mice with dysbiotic microbiota from mice or patients with IBD resulted in increased H₂O₂ production compared with healthy controls. Collectively, these data suggest that IECs are capable of H₂O₂ production during chronic inflammation and dysbiotic states. Our results provide insight into luminal production of H₂O₂ by IECs as a read-out of innate defense by the mucosa.

High fat diet induces microbiota-dependent silencing of enteroendocrine cells

Enteroendocrine cells (EECs) are specialized sensory cells in the intestinal epithelium that sense and transduce nutrient information. Consumption of dietary fat contributes to metabolic disorders, but EEC adaptations to high fat feeding were unknown. Here, we established a new experimental system to directly investigate EEC activity in vivo using a zebrafish reporter of EEC calcium signaling. Our results reveal that high fat feeding alters EEC morphology and converts them into a nutrient insensitive state that is coupled to endoplasmic reticulum (ER) stress. We called this novel adaptation 'EEC silencing'. Gnotobiotic studies revealed that germ-free zebrafish are resistant to high fat diet induced EEC silencing. High fat feeding altered gut microbiota composition including enrichment of Acinetobacter bacteria, and we identified an Acinetobacter strain sufficient to induce EEC silencing. These results establish a new mechanism by which dietary fat and gut microbiota modulate EEC nutrient sensing and signaling.

IL-4 and IL-17A Cooperatively Promote Hydrogen Peroxide Production, Oxidative DNA Damage, and Upregulation of Dual Oxidase 2 in Human Colon and Pancreatic Cancer Cells

Dual oxidase 2 (DUOX2) generates H₂O₂ that plays a critical role in both host defense and chronic inflammation. Previously, we demonstrated that the proinflammatory mediators IFN-γ and LPS enhance expression of DUOX2 and its maturation factor DUOXA2 through STAT1- and NF-κB‒mediated signaling in human pancreatic cancer cells. Using a panel of colon and pancreatic cancer cell lines, we now report the induction of DUOX2/DUOXA2 mRNA and protein expression by the T_H2 cytokine IL-4. IL-4 activated STAT6 signaling that, when silenced, significantly decreased induction of DUOX2. Furthermore, the T_H17 cytokine IL-17A combined synergistically with IL-4 to increase DUOX2 expression in both colon and pancreatic cancer cells mediated, at least in part, by signaling through NF-κB. The upregulation of DUOX2 was associated with a significant increase in the production of extracellular H₂O₂ and DNA damage-as indicated by the accumulation of 8-oxo-dG and γH2AX-which was suppressed by the NADPH oxidase inhibitor diphenylene iodonium and a DUOX2-specific small interfering RNA. The clinical relevance of these experiments is suggested by immunohistochemical, microarray, and quantitative RT-PCR studies of human colon and pancreatic tumors demonstrating significantly higher DUOX2, IL-4R, and IL-17RA expression in tumors than in adjacent normal tissues; in pancreatic adenocarcinoma, increased DUOX2 expression is adversely associated with overall patient survival. These data suggest a functional association between DUOX2-mediated H₂O₂ production and induced DNA damage in gastrointestinal malignancies.

The commensal Escherichia coli CEC15 reinforces intestinal defences in gnotobiotic mice and is protective in a chronic colitis mouse model

Escherichia coli is a regular inhabitant of the gut microbiota throughout life. However, its role in gut health is controversial. Here, we investigated the relationship between the commensal E. coli strain CEC15 (CEC), which we previously isolated, and the intestine in homeostatic and disease-prone settings. The impact of CEC was compared to that of the probiotic E. coli Nissle 1917 (Nissle) strain. The expression of ileal and colonic genes that play a key role in intestinal homeostasis was higher in CEC- and Nissle-mono-associated wild-type mice than in germfree mice. This included genes involved in the turnover of reactive oxygen species, antimicrobial peptide synthesis, and immune responses. The impact of CEC and Nissle on such gene expression was stronger in a disease-prone setting, i.e. in gnotobiotic IL10-deficient mice. In a chronic colitis model, CEC more strongly decreased signs of colitis severity (myeloperoxidase activity and CD3⁺ immune-cell infiltration) than Nissle. Thus, our study shows that CEC and Nissle contribute to increased expression of genes involved in the maintenance of gut homeostasis in homeostatic and inflammatory settings. We show that these E. coli strains, in particular CEC, can have a beneficial effect in a chronic colitis mouse model.

Gut microbiome and cancer immunotherapy

Microbiome is becoming crucial in that the balance between human health and disease can be mediated by the gut microbiome. The gut microbiome can modulate the host immune system both locally and systemically. Cancer immunotherapy has emerged as a promising way in the treatment of patients with cancer. Accumulating evidence supports that microbiome affects the therapeutic efficacy of cancer immunotherapy, particularly immune checkpoint inhibitors. Here, we discuss the mutual relationship among gut microbiome, cancer, immunity, and cancer immunotherapy, with a focus on immunotherapy. Also, we briefly introduce the relevant challenges that affect the therapeutic efficacy and present the possible solutions.

Gastrointestinal Complications in Chronic Granulomatous Disease

Almost half of patients with chronic granulomatous disease (CGD) suffer from gastrointestinal (GI) inflammation, the pathogenesis of which is complex and multifactorial. As a result, the management of CGD-associated GI inflammation remains challenging due to its chronicity and difficulty in managing the simultaneous need for immunomodulation with increased susceptibility to infection. In order to contextualize prospective treatment interventions for CGD-associated GI inflammation, we have reviewed the clinical presentation, pathogenesis and current management of this disease. Increased understanding of the role of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex 2 (NOX2)-derived reactive oxygen species (ROS) in inflammatory bowel disease (IBD) will likely reveal novel targets for therapeutic intervention.

Development of a host-microbiome model of the small intestine

The intestinal epithelium plays an essential role in the balance between tolerant and protective immune responses to infectious agents. In vitro models do not typically consider the innate immune response and gut microbiome in detail, so these models do not fully mimic the physiologic aspects of the small intestine. We developed and characterized a long-term in vitro model containing enterocyte, goblet, and immune-like cells exposed to a synthetic microbial community representative of commensal inhabitants of the small intestine. This model showed differential responses toward a synthetic microbial community of commensal bacterial inhabitants of the small intestine in the absence or presence of LPS from Escherichia coli O111:B4. Simultaneous exposure to LPS and microbiota induced impaired epithelial barrier function; increased production of IL-8, IL-6, TNF-α, and C-X-C motif chemokine ligand 16; and augmented differentiation and adhesion of macrophage-like cells and the overexpression of dual oxidase 2 and TLR-2 and -4 mRNA. In addition, the model demonstrated the ability to assess the adhesion of specific bacterial strains from the synthetic microbial community-more specifically, Veillonella parvula-to the simulated epithelium. This novel in vitro model may assist in overcoming sampling and retrieval difficulties when studying host-microbiome interactions in the small intestine.-Calatayud, M., Dezutter, O., Hernandez-Sanabria, E., Hidalgo-Martinez, S., Meysman, F. J. R., Van de Wiele, T. Development of a host-microbiome model of the small intestine.

Reactive oxygen species in colorectal cancer: The therapeutic impact and its potential roles in tumor progression via perturbation of cellular and physiological dysregulated pathways

Reactive oxygen species (ROS) are produced by mitochondria during metabolism. In physiological states, the production of ROS and their elimination by antioxidants are kept in balance. However, in pathological states, elevated levels of ROS interact with susceptible cellular target compounds including lipids, proteins, and DNA and deregulate oncogenic signaling pathways that are involved in colorectal cancer (CRC) carcinogenesis. Although antioxidant compounds have been successfully used in the treatment of CRC as prevention approaches, they have also been shown in some cases to promote disease progression. In this review, we focus on the role of ROS in gastrointestinal homeostasis, CRC progression, diagnosis, and therapy with particular emphasis on ROS-stimulated pathways.

Dual oxidases participate in the regulation of hemolymph microbiota homeostasis in mud crab Scylla paramamosain

Dual oxidases (DUOXs) were originally identified as NADPH oxidases (NOXs), found to be associated with the reactive oxygen species (ROS) hydrogen peroxide (H₂O₂) production at the plasma membrane and crucial in host biological processes. In this study, SpDUOX1 and SpDUOX2 of mud crab (Scylla paramamosain) were identified and studied. Both SpDUOX1 and SpDUOX2 are transmembrane proteins, including an N-signal peptide region and a peroxidase homology domain in the extracellular region, transmembrane regions, and three EF (calcium-binding region) domains, a FAD-binding domain, and a NAD binding domain in the intracellular region. The SpDUOXs were expressed in all tissues examined, but mainly in hepatopancreas, heart, and mid-intestine. The expression of the SpDUOXs in the hemolymph of mud crabs was up-regulated after challenge with Vibrio parahemolyticus or LPS. RNA interference (RNAi) of the SpDUOXs resulted in reduced ROS production in hemolymph. The bacterial count increased in the hemolymph of mud crabs injected with SpDUOX1 or SpDUOX2-RNAi, while the bacterial clearance ability of hemolymph significantly reduced. At the phylum level, the phyla Bacteroidetes and Actinobacteria were significantly increased, while Proteobacteria were significantly reduced following SpDUOX2 knockdown. There was a significant increase in the relative abundance of the genera Marinomonas, Pseudoalteromonas, Shewanella, and Hydrogenoph in SpDUOX2 depleted mud crabs compared with the controls. Our current findings therefore indicated that SpDUOXs might play important roles in maintaining the homeostasis in the hemolymph microbiota of mud crab.

The Plasma Membrane: A Platform for Intra- and Intercellular Redox Signaling

Membranes are of outmost importance to allow for specific signal transduction due to their ability to localize, amplify, and direct signals. However, due to the double-edged nature of reactive oxygen species (ROS)—toxic at high concentrations but essential signal molecules—subcellular localization of ROS-producing systems to the plasma membrane has been traditionally regarded as a protective strategy to defend cells from unwanted side-effects. Nevertheless, specialized regions, such as lipid rafts and caveolae, house and regulate the activated/inhibited states of important ROS-producing systems and concentrate redox targets, demonstrating that plasma membrane functions may go beyond acting as a securing lipid barrier. This is nicely evinced by nicotinamide adenine dinucleotide phosphate (NADPH)-oxidases (NOX), enzymes whose primary function is to generate ROS and which have been shown to reside in specific lipid compartments. In addition, membrane-inserted bidirectional H₂O₂-transporters modulate their conductance precisely during the passage of the molecules through the lipid bilayer, ensuring time-scaled delivery of the signal. This review aims to summarize current evidence supporting the role of the plasma membrane as an organizing center that serves as a platform for redox signal transmission, particularly NOX-driven, providing specificity at the same time that limits undesirable oxidative damage in case of malfunction. As an example of malfunction, we explore several pathological situations in which an inflammatory component is present, such as inflammatory bowel disease and neurodegenerative disorders, to illustrate how dysregulation of plasma-membrane-localized redox signaling impacts normal cell physiology.

Dual functional roles of the MyD88 signaling in colorectal cancer development

The myeloid differentiation factor 88 (MyD88), an adaptor protein in regulation of the innate immunity, functions to regulate immune responses against viral and bacterial infections in the human body. Toll-like receptors (TLRs) and interleukin 1 receptors (IL-1R) can recognize microbes or endogenous ligands and then recruit MyD88 to activate the MyD88-dependent pathway, while MyD88 mutation associated with lymphoma development and altered MyD88 signaling also involved in cancer-associated cell intrinsic and extrinsic inflammation progression and carcinogenesis. Detection of MyD88 expression was to predict prognosis of various human cancers, e.g., lymphoid, liver, and colorectal cancers. In human cancers, MyD88 protein acts as a bridge between the inflammatory signaling from the TLR/IL-1R and Ras oncogenic signaling pathway. However, the MyD88 signaling played dual functional roles in colorectal cancer, i.e., the tumor-promoting role that enhances cancer inflammation and intestinal flora imbalance to induce tumor invasion and tumor cell self-renewal, and the anti-tumor role that helps to maintain the host-microbiota homeostasis to induce tumor cell cycle arrest and immune responses against cancer cells. This review precisely discusses the up to date literature for these contrasting effects of MyD88 signaling on colorectal cancer development and progression.