Using Diverse Model Systems to Define Intestinal Epithelial Defenses to Enteric Viral Infections

The toxic effects of exposure to fibrous and fragmented microplastic in juvenile rockfish based on two omics approach

Although the hazards of environmental microplastics (MPs) are well known, it is unclear which of their characteristics have the greatest effects on organism. We investigated the toxic effects of oral administration according to physical properties, including the shape of fragmented polyethylene terephthalate (PET) (FrPET) and fibrous PET (FiPET) MPs. After 72 h of exposure, apoptosis and phagocytic activity varied significantly among juvenile rockfish (Sebastes schlegeli) exposed to both FrPET and FiPET. The levels of immune-related genes and hepatic metabolic activity also increased after exposure to both shapes of MPs, but the variation in responses was greater in fish exposed to FiPET compared with those exposed to FrPET. The transcriptomic and metabolomics analysis results indicated that the maintenance and homeostasis of immune system was affected by oral exposure to FrPET and FiPET. The amino acid metabolic processes were identified in rockfish exposed to FrPET, but the notch signaling pathway were evident in the FiPET exposure group. Metabolomics analysis revealed that oral ingestion of MP fibers led to a stronger inflammatory response and greater oxidative stress in juvenile rockfish. These results can be used to understand environmentally dominant MP toxic effects such as type, size, shapes, as well as to prioritize ecotoxicological management.

Plant-Derived as Alternatives to Animal-Derived Bioactive Peptides: A Review of the Preparation, Bioactivities, Structure-Activity Relationships, and Applications in Chronic Diseases

Background/Objectives: At present, a large number of bioactive peptides have been found from plant sources with potential applications for the prevention of chronic diseases. By promoting plant-derived bioactive peptides (PDBPs), we can reduce dependence on animals, reduce greenhouse gas emissions, and protect the ecological environment. Methods: In this review, we summarize recent advances in sustainably sourced PDBPs in terms of preparation methods, biological activity, structure-activity relationships, and their use in chronic diseases. Results: Firstly, the current preparation methods of PDBPs were summarized, and the advantages and disadvantages of enzymatic method and microbial fermentation method were introduced. Secondly, the biological activities of PDBPs that have been explored are summarized, including antioxidant, antibacterial, anticancer and antihypertensive activities. Finally, based on the biological activity, the structure-activity relationship of PDBPs and its application in chronic diseases were discussed. All these provide the foundation for the development of PDBPs. However, the study of PDBPs still has some limitations. Conclusions: Overall, PDBPs is a good candidate for the prevention and treatment of chronic diseases in humans. This work provides important information for exploring the source of PDBPs, optimizing its biological activity, and accurately designing functional foods or drugs.

Effects of bamboo leaf flavonoids on growth performance, antioxidants, immune function, intestinal morphology, and cecal microbiota in broilers

BACKGROUND

Bamboo leaf flavonoids (BLF) are the main bioactive ingredients in bamboo leaves. They have antioxidant, anti-inflammatory, antibacterial, and other effects. In this study, the effects of dietary BLF on growth performance, immune response, antioxidant capacity, and intestinal microbiota of broilers were investigated. A total of 288 broilers were divided into three groups with eight replicates and 12 birds in each replicate. Broilers were fed a basic diet or the basic diet supplemented with 1000 or 2000 mg kg-1 BLF for 56 days.

RESULTS

The results showed that supplementation of BLF increased body weight (BW) and average daily weight gain (ADG), and reduced average daily feed intake (ADFI) (P < 0.05). The serum immunoglobulin A (IgA), immunoglobulin M (IgM), and interleukin 10 (IL-10) content of broilers in the BLF1000 group was increased and the interleukin 1β (IL-1β) and tumor necrosis factor-α (TNF-α) content was decreased (P < 0.05). The levels of IgM and IL-10 in jejunum mucosa were found to be enhanced by BLF (P < 0.05). The BLF1000 group exhibited a significant reduction in the concentration of TNF-α (P < 0.05). Serum and jejunum mucosa total antioxidant capacity (T-AOC) levels in the BLF1000 group were increased (P < 0.05). The serum catalase (CAT) and glutathione peroxidase (GSH-Px) effects of the BLF1000 group and serum CAT effects of BLF2000 group were increased (P < 0.05). The CON group demonstrated a lower relative abundance of Christensenellaceae_R-7_group and Oscillibacter than the BLF group (P < 0.05).

CONCLUSION

Dietary BLF inclusion enhanced the growth performance, immune, and antioxidant functions, improved the intestinal morphology, and ameliorated the intestinal microflora structure in broiler. Adding 1000 mg kg-1 BLF to the broiler diet can be considered as an effective growth promoter. © 2024 Society of Chemical Industry.

Orostachys malacophylla (pall.) fisch extracts alleviate intestinal inflammation in Drosophila

ETHNOPHARMACOLOGICAL RELEVANCE

Orostachys malacophylla (Pall.) Fisch (O. malacophylla) is a succulent herbaceous plant that is the Orostachys genus of Crassulaceae family. O. malacophylla has been widely used as a traditional Chinese medicine with antioxidant, anti-inflammatory, anti-febrile, antidote, anti-Toxoplasma gondii properties. However, the biological function of alleviating intestinal inflammation and key bioactive compounds were still unknown.

AIM OF THE STUDY

We used a Drosophila model to study the protective effects and bioactive compounds of O. malacophylla water extract (OMWE) and butanol extract (OMBE) on intestinal inflammation.

MATERIALS AND METHODS

Drosophila intestinal inflammation was induced by oral invasion of dextran sodium sulfate (DSS) or Erwinia carotovora carotovora 15 (Ecc15). We revealed the protective effects of two extracts by determining intestinal reactive oxygen species (ROS) and antimicrobial peptide (AMP) levels and intestinal integrity, and using network pharmacology analysis to identify bioactive compounds.

RESULTS

We demonstrated that both OMWE and OMBE could ameliorate the detrimental effects of DSS, including a decreased survival rate, elevated ROS levels, increased cell death, excessive proliferation of ISCs, acid-base imbalance, and disruption of intestinal integrity. Moreover, the overabundance of lipid droplets (LDs) and AMPs by Ecc15 infection is mitigated by these extracts, thereby enhancing the flies' resistance to adverse stimuli. In addition, we used widely targeted metabolomics and network pharmacology analysis to identify bioactive compounds associated with IBD healing that are present in OMWE and OMBE.

CONCLUSIONS

In summary, our research indicates that OMWE and OMBE significantly mitigate intestinal inflammation and have the potential to be effective therapeutic agents for IBD in humans.

ROS-responsive carboxymethyl chitosan nanoparticles loaded with astaxanthin for alleviating oxidative damage in intestinal cells

The controlled release of antioxidant substances at the intestinal oxidative damage site is crucial for alleviating intestine-related diseases. Herein, the novel ROS-responsive carrier was synthesized through simple amidation reaction between carboxymethyl chitosan (CMC) and methionine (Met), a natural organic compound containing ROS-responsive linkages (thioether). Initially, astaxanthin (AXT) nanoparticles (AXT2@CMT) with excellent stability and drug loading capacity (39.68 ± 0.23 μg/mL) were prepared by optimizing various reaction conditions. In the simulated high-concentration ROS environment of the intestine, CMT achieved a transition from hydrophobic groups (thioether) into hydrophilic groups (sulfone), which was conducive to the controlled release of AXT. In vitro cell experiments revealed that AXT2@CMT could effectively alleviate the oxidative damage in intestinal epithelioid cell line No. 6 (IEC-6 cell) caused by H2O2. This study achieved a straightforward preparation of ROS-responsive nanocarrier through food ingredients, offering a theoretical foundation for the controlled release of AXT at the intestinal oxidative damage site.

Cellular and molecular organization of the Drosophila foregut

The animal foregut is the first tissue to encounter ingested food, bacteria, and viruses. We characterized the adult Drosophila foregut using transcriptomics to better understand how it triages consumed items for digestion or immune response and manages resources. Cell types were assigned and validated using GFP-tagged and Gal4 reporter lines. Foregut-associated neuroendocrine cells play a major integrative role by coordinating gut activity with nutrition, the microbiome, and circadian cycles; some express clock genes. Multiple epithelial cell types comprise the proventriculus, the central foregut organ that secretes the peritrophic matrix (PM) lining the gut. Analyzing cell types synthesizing individual PM layers revealed abundant mucin production close to enterocytes, similar to the mammalian intestinal mucosa. The esophagus and salivary gland express secreted proteins likely to line the esophageal surface, some of which may generate a foregut commensal niche housing specific gut microbiome species. Overall, our results imply that the foregut coordinates dietary sensing, hormonal regulation, and immunity in a manner that has been conserved during animal evolution.

Human gut homeostasis and regeneration: the role of the gut microbiota and its metabolites

The healthy human gut is a balanced ecosystem where host cells and representatives of the gut microbiota interact and communicate in a bidirectional manner at the gut epithelium. As a result of these interactions, many local and systemic processes necessary for host functionality, and ultimately health, take place. Impairment of the integrity of the gut epithelium diminishes its ability to act as an effective gut barrier, can contribute to conditions associated to inflammation processes and can have other negative consequences. Pathogens and pathobionts have been linked with damage of the integrity of the gut epithelium, but other components of the gut microbiota and some of their metabolites can contribute to its repair and regeneration. Here, we review what is known about the effect of bacterial metabolites on the gut epithelium and, more specifically, on the regulation of repair by intestinal stem cells and the regulation of the immune system in the gut. Additionally, we explore the potential therapeutic use of targeted modulation of the gut microbiota to maintain and improve gut homeostasis as a mean to improve health outcomes.

Zingerone attenuates intestinal injury and colitis caused by a high-fat diet through Nrf2 signaling regulation

This study examined the protective effect of Zingerone against a high-fat diet (HFD)-induced intestinal damage. Control and HFD rats were treated with the vehicle or Zingerone (100 mg/kg, orally) (n = 8 rats/groups). An extra group, HFD + Zingerone + brusatol (an Nrf2 inhibitor). This study treatment lasted four weeks. Zingerone reduced the nuclear levels of NF-B p65 in control and HFD-fed rats while increasing SOD, CAT, GSH, levels of mRNA, cytoplasmic levels, and Nrf2 nuclear levels. Zingerone treatment attenuated the duodenal epithelial damage and maintained the mucosal barrier by reducing plasma FITC-DX and serum LPS in rats fed with HFD. Concomitantly, it lowered the duodenal MDA, TNF-α, IL-6, and IL-1β levels. These impacts included changes in body weight, duodenal lipid levels, and Keap-1 expression, a natural Nrf2 inhibitor. We concluded that Zingerone reduces HFD-induced duodenal injury. These findings support Zingerone's clinical applicability against various inflammatory diseases of the intestine.

Oxidative stress in Wernicke's encephalopathy

Wernicke's encephalopathy (WE) is a severe life-threatening disease that occurs due to vitamin B1 (thiamine) deficiency (TD). It is characterized by acute mental disorder, ataxia, and ophthalmoplegia. TD occurs because of the following reasons: insufficient intake, increased demand, and long-term drinking due to corresponding organ damage or failure. Recent studies showed that oxidative stress (OS) can damage organs and cause TD in the brain, which further leads to neurodegenerative diseases, such as WE. In this review, we discuss the effects of TD caused by OS on multiple organ systems, including the liver, intestines, and brain in WE. We believe that strengthening the human antioxidant system and reducing TD can effectively treat WE.

Quercetin Prevents Intestinal Stem Cell Aging via Scavenging ROS and Inhibiting Insulin Signaling in Drosophila

Adult stem cells, a class of cells that possess self-renewal and differentiation capabilities, modulate tissue regeneration, repair, and homeostasis maintenance. These cells undergo functional degeneration during aging, resulting in decreased tissue regeneration ability and increased disease incidence. Thus, it is essential to provide effective therapeutic solutions to preventing the aging-related functional decline of stem cells. Quercetin (Que) is a popular natural polyphenolic flavonoid found in various plant species. It exhibits many beneficial effects against aging and aging-related diseases; however, its efficacy against adult stem cell aging remains largely unclear. Drosophila possesses a mammalian-like intestinal system with a well-studied intestinal stem cell (ISC) lineage, making it an attractive model for adult stem cell research. Here, we show that Que supplementation could effectively prevent the hyperproliferation of ISCs, maintain intestinal homeostasis, and prolong the lifespan in aged Drosophila. In addition, we found that Que could accelerate recovery of the damaged gut and improve the tolerance of Drosophila to stressful stimuli. Furthermore, results demonstrated that Que prevents the age-associated functional decline of ISCs via scavenging reactive oxygen species (ROS) and inhibiting the insulin signaling pathway. Overall, our findings suggest that Que plays a significant role in delaying adult stem cell aging.

The Role of Intestinal Mucosal Barrier in Autoimmune Disease: A Potential Target

Autoimmune diseases are a series of diseases involving multiple tissues and organs, characterized by the over production of abnormal multiple antibodies. Although most studies support that the impaired immune balance participates in the development of autoimmune diseases, the specific pathogenesis of it is not fully understood. Intestinal immunity, especially the intestinal mucosal barrier has become a research hotspot, which is considered to be an upstream mechanism leading to the impaired immune balance. As an important defense barrier, the intestinal mucosal barrier regulates and maintains the homeostasis of internal environment. Once the intestinal barrier function is impaired under the effect of multiple factors, it will destroy the immune homeostasis, trigger inflammatory response, and participate in the development of autoimmune diseases in the final. However, the mechanism of the intestinal mucosal barrier how to regulate the homeostasis and inflammation is not clear. Some studies suggest that it maintains the balance of immune homeostasis through the zonulin pathway, intestinal microbiome, and Toll-like receptor signaling pathway. Our review focused on the composition and the function of the intestinal mucosal barrier to describe the research progress of it in regulating the immune homeostasis and inflammation, and also pointed that the intestinal mucosal barrier was the potential targets in the treatment of autoimmune diseases.

Pathogen infection routes and host innate immunity: Lessons from insects

Recent advances in insect-pathogen interactions have started to reveal the role of insect tissues and organs as natural infection routes for parasites and microbial pathogens. Here we summarize this information highlighting the micro- and macro-parasites that enter insects through distinct infection routes and link them to innate immune activity. We also examine whether the infection route determines the insect immune response and if the resulting immunological and physiological processes underpinning these different routes of infection are clearly distinct. Understanding how the infection route is associated with the robustness in insect host defense will help us identify conserved evolutionary and ecological patterns in order to design novel strategies for the management of destructive agricultural pests and disease vectors.

β-defensin 118 attenuates inflammation and injury of intestinal epithelial cells upon enterotoxigenic Escherichia coli challenge

Background

Antimicrobial peptides including various defensins have been attracting considerable research interest worldwide, as they have potential to substitute for antibiotics. Moreover, AMPs also have immunomodulatory activity. In this study, we explored the role and its potential mechanisms of β-defensin 118 (DEFB118) in alleviating inflammation and injury of IPEC-J2 cells (porcine jejunum epithelial cell line) upon the enterotoxigenic Escherichia coli (ETEC) challenge.

Results

The porcine jejunum epithelial cell line (IPEC-J2) pretreated with or without DEFB118 (25 μg/mL) were challenged by ETEC (1×10⁶ CFU) or culture medium. We showed that DEFB118 pretreatment significantly increased the cell viability (P<0.05) and decreased the expressions of inflammatory cytokines such as the interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) in IPEC-J2 cells exposure to ETEC (P<0.05). Interestingly, DEFB118 pretreatment significantly elevated the abundance of the major tight-junction protein zonula occludens-1 (ZO-1), but decreased the number of apoptotic cells upon ETEC challenge (P<0.05). The expression of caspase 3, caspase 8, and caspase 9 were downregulated by DEFB118 in the IPEC-J2 cells exposure to ETEC (P<0.05). Importantly, DEFB118 suppressed two critical inflammation-associated signaling proteins, nuclear factor-kappa-B inhibitor alpha (IκB-α) and nuclear factor-kappaB (NF-κB) in the ETEC-challenged IPEC-J2 cells.

Conclusions

DEFB118 can alleviate ETEC-induced inflammation in IPEC-J2 cells through inhibition of the NF-κB signaling pathway, resulting in reduced secretion of inflammatory cytokines and decreased cell apoptosis. Therefore, DEFB118 can act as a novel anti-inflammatory agent.

Bacterial and Viral Co-Infection in the Intestine: Competition Scenario and Their Effect on Host Immunity

Bacteria and viruses are both important pathogens causing intestinal infections, and studies on their pathogenic mechanisms tend to focus on one pathogen alone. However, bacterial and viral co-infections occur frequently in clinical settings, and infection by one pathogen can affect the severity of infection by another pathogen, either directly or indirectly. The presence of synergistic or antagonistic effects of two pathogens in co-infection can affect disease progression to varying degrees. The triad of bacterial–viral–gut interactions involves multiple aspects of inflammatory and immune signaling, neuroimmunity, nutritional immunity, and the gut microbiome. In this review, we discussed the different scenarios triggered by different orders of bacterial and viral infections in the gut and summarized the possible mechanisms of synergy or antagonism involved in their co-infection. We also explored the regulatory mechanisms of bacterial–viral co-infection at the host intestinal immune interface from multiple perspectives.

The transcription factor ZIP-1 promotes resistance to intracellular infection in Caenorhabditis elegans

Defense against intracellular infection has been extensively studied in vertebrate hosts, but less is known about invertebrate hosts; specifically, the transcription factors that induce defense against intracellular intestinal infection in the model nematode Caenorhabditis elegans remain understudied. Two different types of intracellular pathogens that naturally infect the C. elegans intestine are the Orsay virus, which is an RNA virus, and microsporidia, which comprise a phylum of fungal pathogens. Despite their molecular differences, these pathogens induce a common host transcriptional response called the intracellular pathogen response (IPR). Here we show that zip-1 is an IPR regulator that functions downstream of all known IPR-activating and regulatory pathways. zip-1 encodes a putative bZIP transcription factor, and we show that zip-1 controls induction of a subset of genes upon IPR activation. ZIP-1 protein is expressed in the nuclei of intestinal cells, and is at least partially required in the intestine to upregulate IPR gene expression. Importantly, zip-1 promotes resistance to infection by the Orsay virus and by microsporidia in intestinal cells. Altogether, our results indicate that zip-1 represents a central hub for triggers of the IPR, and that this transcription factor has a protective function against intracellular pathogen infection in C. elegans.

Intestinal immune responses to intracellular infection of Caenorhabditis elegans and other Invertebrate hosts are not well understood. Here the authors show a key role for the transcription factor ZIP-1 during intestinal intracellular infection.

Brain inflammation triggers macrophage invasion across the blood-brain barrier in Drosophila during pupal stages

The nervous system is shielded from circulating immune cells by the blood-brain barrier (BBB). During infections and autoimmune diseases, macrophages can enter the brain where they participate in pathogen elimination but can also cause tissue damage. Here, we establish a Drosophila model to study macrophage invasion into the inflamed brain. We show that the immune deficiency (Imd) pathway, but not the Toll pathway, is responsible for attraction and invasion of hemolymph-borne macrophages across the BBB during pupal stages. Macrophage recruitment is mediated by glial, but not neuronal, induction of the Imd pathway through expression of Pvf2. Within the brain, macrophages can phagocytose synaptic material and reduce locomotor abilities and longevity. Similarly, we show that central nervous system infection by group B Streptococcus elicits macrophage recruitment in an Imd-dependent manner. This suggests that evolutionarily conserved inflammatory responses require a delicate balance between beneficial and detrimental activities.

Gut Susceptibility to Viral Invasion: Contributing Roles of Diet, Microbiota and Enteric Nervous System to Mucosal Barrier Preservation

The gastrointestinal lumen is a rich source of eukaryotic and prokaryotic viruses which, together with bacteria, fungi and other microorganisms comprise the gut microbiota. Pathogenic viruses inhabiting this niche have the potential to induce local as well as systemic complications; among them, the viral ability to disrupt the mucosal barrier is one mechanism associated with the promotion of diarrhea and tissue invasion. This review gathers recent evidence showing the contributing effects of diet, gut microbiota and the enteric nervous system to either support or impair the mucosal barrier in the context of viral attack.

Sensing and signalling viral infection in drosophila

The fruitfly Drosophila melanogaster is a valuable model to unravel mechanisms of innate immunity, in particular in the context of viral infections. RNA interference, and more specifically the small interfering RNA pathway, is a major component of antiviral immunity in drosophila. In addition, the contribution of inducible transcriptional responses to the control of viruses in drosophila and other invertebrates is increasingly recognized. In particular, the recent discovery of a STING-IKKβ-Relish signalling cassette in drosophila has confirmed that NF-κB transcription factors play an important role in the control of viral infections, in addition to bacterial and fungal infections. Here, we review recent developments in the field, which begin to shed light on the mechanisms involved in sensing of viral infections and in signalling leading to production of antiviral effectors.

Combination of Mesenchymal Stem Cell and Endothelial Progenitor Cell Infusion Accelerates Injured Intestinal Repair by Regulating Gut Microbiota after Hematopoietic Cell Transplantation

Mesenchymal stem cells (MSC) have been widely applied for repairing intestinal barrier function and restoring immune homeostasis for pretransplantation conditioning, yet the repair process is often impaired or delayed owing to a lack of vascularity. How combined therapy with MSC and endothelial progenitor cells (EPC) for the intestinal microenvironment and repair remain unclear. In this study, BALB/c mice received syngeneic bone marrow transplantation with or without MSC or EPC infusion. The findings show that the MSC+EPC mice had greater blood capillary distribution and higher expression of tight junction protein (occludin) in the small intestinal tract. Meanwhile, the MSC+EPC cotreatment increased IL-17A levels and decreased IFN-γ levels at the early stage after transplantation. Furthermore, the MSC+EPC treatment motivated p38 mitogen-activated protein kinase (MAPK) and enhanced heat shock protein 27 (HSP27) activation, which subsequently promoted intestinal epithelial cell proliferation and down-regulated apoptosis-related molecule caspase 3 expression. Finally, the high-throughput sequencing of gut microbiota (16S) showed that the MSC+EPC treatment can inhibit the Enterococcus population (<0.5%) and stabilize the Akkermansia population (~15%), with the Akkermansia population showing significant positive correlations with p38 MAPK/phos-p38, HSP27/phos-HSP27, IL-17A, and occludin. Taken together, our results show that MSC+EPC combined therapy is beneficial for the repair of injured intestine and drives gut microbial community stability by regulating the intestinal microenvironment.

Enteric Viral Co-Infections: Pathogenesis and Perspective

Enteric viral co-infections, infections involving more than one virus, have been reported for a diverse group of etiological agents, including rotavirus, norovirus, astrovirus, adenovirus, and enteroviruses. These pathogens are causative agents for acute gastroenteritis and diarrheal disease in immunocompetent and immunocompromised individuals of all ages globally. Despite virus–virus co-infection events in the intestine being increasingly detected, little is known about their impact on disease outcomes or human health. Here, we review what is currently known about the clinical prevalence of virus–virus co-infections and how co-infections may influence vaccine responses. While experimental investigations into enteric virus co-infections have been limited, we highlight in vivo and in vitro models with exciting potential to investigate viral co-infections. Many features of virus–virus co-infection mechanisms in the intestine remain unclear, and further research will be critical.