Intestinal Response Research Articles

Nasal and Pharyngeal Mucosal Immunity to Poliovirus in Children Following Routine Immunization With Inactivated Polio Vaccine in the United States.

Although polioviruses (PVs) replicate in lymphoid tissue of both the pharynx and ileum, research on polio vaccine-induced mucosal immunity has predominantly focused on intestinal neutralizing and binding antibody levels measured in stool. To investigate the extent to which routine immunization with intramuscularly injected inactivated polio vaccine (IPV) may induce nasal and pharyngeal mucosal immunity, we measured PV type-specific neutralization and immunoglobulin (Ig) G, IgA, and IgM levels in nasal secretions, adenoid cell supernatants, and sera collected from 12 children, aged 2-5 years, undergoing planned adenoidectomies. All participants were routinely immunized with IPV and had no known contact with live PVs. PV-specific mucosal neutralization was detected in nasal and adenoid samples, mostly from children who had previously received 4 IPV doses. Across the 3 PV serotypes, both nasal (Spearman ρ ≥ 0.87, P ≤ .0003 for all) and adenoid (Spearman ρ ≥ 0.57, P ≤ .05 for all) neutralization titers correlated with serum neutralization titers. In this small study sample, there was insufficient evidence to determine which Ig isotype(s) was correlated with neutralization. Our findings provide policy-relevant evidence that routine immunization with IPV may induce nasal and pharyngeal mucosal immunity. The observed correlations of nasal and pharyngeal mucosal neutralization with serum neutralization contrast with previous observations of distinct intestinal and serum responses to PV vaccines. Further research is warranted to determine which antibody isotype(s) correlate with polio vaccine-induced nasal and pharyngeal mucosal neutralizing activity and to understand the differences from intestinal mucosal immunity.

HSP70 protects against acute pancreatitis-elicited intestinal barrier damage in rats

Acute pancreatitis (AP) is a frequent but severe abdominal emergency in general surgery with intestinal barrier dysfunction. Heat shock protein 70 (HSP70) is a ubiquitous molecular chaperone that has been proposed to exert favorable effects on AP. Nonetheless, the detailed impacts of HSP70 on the intestinal barrier function in AP are unknown, which will be investigated here. After the injection of sodium taurocholate into the biliopancreatic duct, the rat models of AP were established. After modeling, HSP70 expression was up-regulated through lentivirus infection. Western blot was used to detect HSP70 expression. H&E staining was used to examine the histological changes in the pancreatic and intestinal tissues. The levels of pancreatic biochemical markers and oxidative stress markers were detected using corresponding assay kits. ELISA was used to detect the levels of inflammatory cytokines and gastrointestinal function indicators. Immunofluorescence staining and Western blot were used to detect the expression of tight junction proteins. DCFH-DA probe and MitoSOX Red probe were used to detect total reactive oxygen species (ROS) and mitochondrial ROS (mtROS), respectively. TUNEL assay and Western blot were used to detect apoptosis. During the model construction, severe pancreatic and abnormal intestinal tissue abnormalities were observed, inflammatory response was activated and the intestinal barrier was disrupted. HSP70 expression was down-regulated in the intestinal tissues AP rat models. HSP70 ameliorated the morphological damage of pancreatic and intestinal tissues of AP rats. In addition, HSP70 significantly reduced intestinal barrier damage, inflammatory response, oxidative stress and apoptosis in the intestinal tissues of AP rat models. Collectively, HSP70 might attenuate AP through exerting anti-inflammatory, anti-oxidant, anti-apoptotic effects and inhibiting intestinal barrier disruption.

Effects of dietary vitamin D3 and carbohydrate levels on growth performance, carbohydrate metabolism, and intestinal health of yellow catfish (Pelteobagrus fulvidraco)

The study was performed to determine effects of vitamin D3 (VD3) and carbohydrate levels in the diets on growth, carbohydrate absorption and metabolism, and intestinal health of yellow catfish (Pelteobagrus fulvidraco). Four groups of yellow catfish with an average weight of 4.12 ± 0.00 g were provided with diets containing varying proportions of VD3 and carbohydrate. These diets included two VD3 levels at 1000 IU/kg (basic VD3) and 16,100 IU/kg diet (high VD3), each containing carbohydrate levels of 25% and 35%, respectively. After analyzing dietary VD3 and carbohydrate contents, these groups were labeled as follows: the control (30.78% carbohydrates +1040 IU/kg), the VD3 group (30.67% carbohydrates +16,041 IU/kg), the high-carbohydrate group (HCD group, 39.65% carbohydrates +1017 IU/kg), and the HCD + VD3 group (39.67% carbohydrates +16,061 IU/kg). Each tank consisted of three replicates, with each replicate containing 30 fish. The experiment continued for 10 weeks. Compared with the control, HCD group reduced growth performance, the muscular layer thickness, the zonulae occludentes1 and 3 (zo1, zo3), junctional adhesion molecules 3a (jam3a), claudin1, occludin, phosphoglucomutase 1 (pgm1) mRNA expression, but increased intestinal villi height, glycogen content, glycogen synthase (gs), glycogen branching enzyme (gbe), sodium/glucose cotransporter 1 and 2 (sglt1, sglt2) and glucose transporter 2 (glut2) mRNA expression, solute carrier family 5 member 1 (SGLT1) protein expression, and dietary VD3 group alleviated HCD-induced variations of these indices mentioned above. Compared to the control, HCD group significantly suppressed pyruvate carboxylase b (pcxb), phosphoenolpyruvate carboxykinase (pepck), interleukin10 (il10), NFE2 like bZIP transcription factor 2 (nrf2), superoxide dismutase 2 (sod2) and catalase 1 (cat1) mRNA expression, and also inhibited the activities of glutathione peroxidase (GPX), catalase (CAT), total superoxide dismutase (T-SOD) and total antioxidant capacity (T-AOC), but increased hexokinase 1 (hk1), glucokinase (gk), 1-phosphofructokinase (pfkb), interleukin 1β (il1β), interleukin 6 (il6), tumor necrosis factor a and β (tnfa, tnfβ) mRNA expression, and malondialdehyde (MDA) content; dietary VD3 group further suppressed gluconeogenic genes (pcxb, pepck) expression, but significantly enhanced the expression of glycolytic genes (hk1, gk, pfkp). Dietary VD3 also alleviated HCD-induced variations of these indices involved in antioxidant and inflammatory responses in yellow catfish intestine. Based on these results, our study indicated that dietary VD3 contributed to alleviate HCD-induced adverse effects on intestinal carbohydrate utilization and health. Our study also elucidated the innovative insights into the interaction of HCD and VD3 in fish, and provided the potential strategies for improving dietary carbohydrate utilization of fish via VD3 addition in aquafeeds. These findings can potentially contribute to cost savings for businesses and serve as a reference for optimizing feed formulations.

Fasting before Intra-Gastric Dosing with Antigen Improves Intestinal Humoral Responses in Syrian Hamsters.

Oral vaccines, unlike injected, induce intestinal secretory immunoglobulin A (sIgA) mimicking our natural defense against gut pathogens. We previously observed sIgA responses after administering the Clostridioides difficile colonisation factor CD0873 orally in enteric capsules to hamsters. Enteric-coated capsules are designed to resist dissolution in the stomach and disintegrate only at the higher pH of the small intestine. However, the variable responses between animals led us to speculate suboptimal transit of antigens to the small intestine. The rate of gastric emptying is a controlling factor in the passage of oral drugs for subsequent availability in the small intestine for absorption. Whilst in humans, food delays gastric emptying, in rats, capsules can empty quicker from fed stomachs than from fasted. To test in hamsters if fasting improves the delivery of antigens to the small intestine, as inferred from the immune responses generated, 24 animals were dosed intragastrically with enteric capsules containing recombinant CD0873. Twelve hamsters were fasted for 12 h prior to each dose and the other 12 fed. Significantly higher sIgA titres, with significantly greater bacterial-adherence-blocking activity, were detected in small intestinal lavages in the fasted group. We conclude that fasting in hamsters improves intestinal delivery leading to more robust responses.

Acute and Long COVID Intestinal Changes in an Experimental Model of Coronavirus in Mice.

The COVID-19 pandemic, which emerged in early 2020, has had a profound and lasting impact on global health, resulting in over 7.0 million deaths and persistent challenges. In addition to acute concerns, there is growing attention being given to the long COVID health consequences for survivors of COVID-19 with documented cases of cardiovascular abnormalities, liver disturbances, lung complications, kidney issues, and noticeable cognitive deficits. Recent studies have investigated the physiological changes in various organs following prolonged exposure to murine hepatitis virus-1 (MHV-1), a coronavirus, in mouse models. One significant finding relates to the effects on the gastrointestinal tract, an area previously understudied regarding the long-lasting effects of COVID-19. This research sheds light on important observations in the intestines during both the acute and the prolonged phases following MHV-1 infection, which parallel specific changes seen in humans after exposure to SARS-CoV-2. Our study investigates the histopathological alterations in the small intestine following MHV-1 infection in murine models, revealing significant changes reminiscent of inflammatory bowel disease (IBD), celiac disease. Notable findings include mucosal inflammation, lymphoid hyperplasia, goblet cell hyperplasia, and immune cell infiltration, mirroring pathological features observed in IBD. Additionally, MHV-1 infection induces villous atrophy, altered epithelial integrity, and inflammatory responses akin to celiac disease and IBD. SPIKENET (SPK) treatment effectively mitigates intestinal damage caused by MHV-1 infection, restoring tissue architecture and ameliorating inflammatory responses. Furthermore, investigation into long COVID reveals intricate inflammatory profiles, highlighting the potential of SPK to modulate intestinal responses and restore tissue homeostasis. Understanding these histopathological alterations provides valuable insights into the pathogenesis of COVID-induced gastrointestinal complications and informs the development of targeted therapeutic strategies.

Quorum-Sensing Signal DSF Inhibits the Proliferation of Intestinal Pathogenic Bacteria and Alleviates Inflammatory Response to Suppress DSS-Induced Colitis in Zebrafish.

The imbalance of gut microbiota is an important factor leading to inflammatory bowel disease (IBD). Diffusible signal factor (DSF) is a novel quorum-sensing signal that regulates bacterial growth, metabolism, pathogenicity, and host immune response. This study aimed to explore the therapeutic effect and underlying mechanisms of DSF in a zebrafish colitis model induced by sodium dextran sulfate (DSS). The results showed that intake of DSF can significantly improve intestinal symptoms in the zebrafish colitis model, including ameliorating the shortening of the intestine, reducing the increase in the goblet cell number, and restoring intestinal pathological damage. DSF inhibited the upregulation of inflammation-related genes and promoted the expression of claudin1 and occludin1 to protect the tightness of intestinal tissue. The gut microbiome analysis demonstrated that DSF treatment helped the gut microbiota of the zebrafish colitis model recover to normal at the phylum and genus levels, especially in terms of pathogenic bacteria; DSF treatment downregulated the relative abundance of Aeromonas hydrophila and Staphylococcus aureus, and it was confirmed in microbiological experiments that DSF could effectively inhibit the colonization and infection of these two pathogens in the intestine. This study suggests that DSF can alleviate colitis by inhibiting the proliferation of intestinal pathogens and inflammatory responses in the intestine. Therefore, DSF has the potential to become a dietary supplement that assists in the antibiotic and nutritional treatment of IBD.

Decoding the intestinal response to heat stress in Gymnocypris eckloni: Insights from a thorough analysis of microbiome and transcriptome

The Qinghai-Tibetan Plateau has exhibited heightened sensitivity to global warming than any other region. G. ekloni, an endemic fish of the Qinghai-Tibetan Plateau, holds ecological significance and is a key highland cold-water species in Chinese aquaculture. However, the warming of its habitat poses a significant threat to its survival. The intestine serves as the primary line of external immune defense. There are no reports available on alterations in the intestine of G. eckloni in response to varying levels of heat stress. In this study, G. ekloni was categorized into the optimum temperature culture group (CO, control group), the 22 °C heat stress culture group (HT-22) and the 28 °C heat stress culture group (HT-28).The adaptability of G. ekloni intestine to varying levels of heat stress was investigated through a comprehensive analysis involving tissue sections, blood biochemical indexes, sequencing of 16S and RNA-Seq. Tissue sections showed severe intestinal damage in the HT-28, characterized by mucosal layer necrosis, swelling of thrush cells, and erosion of villi. In the HT-28 group, the significantly increased plasma levels of inflammatory markers (DAO, LPS, IL-1β, IL-6, and TNF-α) also corroborated the substantial impairment of intestinal barrier function. Meanwhile, the RNA-Seq analysis revealed a significant upregulation of most genes in the HIF-1 signaling pathway. This suggests that the HIF-1 signaling pathway likely plays a crucial role in safeguarding the intestinal tract from injuries caused by extreme temperature stress.Intriguingly, there was very little change in the intestinal histological structure and no significant changes in biochemical indicators of stress and inflammation in the blood in the HT-22 group, and 16S amplification sequencing also revealed a greater abundance of intestinal microbial species in the HT-22 group. Through co-analysis with the up-regulated DEGs in HT-22, it was determined that the augmentation of intestinal flora taxa in the HT-22 group positively contributing to enhancing intestinal immunity and stabilizing intestinal barrier. This comprehensive histomorphological and multi-omics study showcased the resilience of G. ekloni intestine to environmental warming. The findings offer fundamental data for future research on the artificial culture of highland economic fishes, and their environmental adaptations.

A biofloc system avoids the adverse effects of diets with suboptimal protein levels on zootechnical performance, intestinal histomorphometry, and protein metabolism of Nile tilapia juvenile fed Spirulina biomass (Arthrospira platensis) as an alternative protein source.

This study aimed to evaluate the effect of the biofloc technology (BFT) system and the replacement of fish meal with Spirulina biomass on productive performance, intestinal histomorphometry, plasma biochemistry, and oxidative stress of Nile tilapia juveniles (Oreochromis niloticus) fed suboptimal levels of protein. Two factors were evaluated: production systems (clear water × BFT) and replacement of fish meal with Spirulina (0, 33, 66 e 100%). The design was in a 2 × 4 randomized factorial scheme with four replications, and the fish were evaluated for 48days. Four isoproteic (28% crude protein) diets were formulated with gross energy values close to 4300kcalkg-1. Nile tilapia juveniles (0.23 ± 0.01g) were distributed in 16 circular tanks (70 L) at seven fish/tank. The diets were formulated with protein levels approximately 20% below that required for the species and life stage. No interaction was observed between the factors evaluated (production systems × Spirulina inclusion). Rearing the fish in the BFT system avoided the adverse effects of diets with suboptimal protein levels on performance, intestinal histomorphometry, and protein metabolism. Lower values lower lipid peroxidation and higher antioxidant capacity were observed in fish reared in the BFT system, showing evidence of improvements in antioxidant responses and lower levels of physiological oxidative stress. Spirulina completely replaced fish meal in the diets of Nile tilapia juveniles without adverse effects on intestinal morphometry, protein metabolism, and antioxidant response. Replacing 66% of fish meal with Spirulina improved the productive performance, regardless of the rearing system.

MiR-146a alleviates inflammatory bowel disease in mice through systematic regulation of multiple genetic networks.

Inflammatory bowel disease (IBD) is a chronic disease involving multiple genes, and the current available targeted drugs for IBD only deliver moderate efficacy. Whether there is a single gene that systematically regulates IBD is not yet known. MiR-146a plays a pivotal role in repression of innate immunity, but its function in the intestinal inflammation is sort of controversy, and the genetic regulatory networks regulated by miR-146a in IBD has not been revealed. RT-qPCR was employed to detect the expression of miR-146a in IBD patients and in a mouse IBD model induced by dextran sulfate sodium (DSS), and then we generated a miR-146a knock-out mouse line with C57/Bl6N background. The disease activity index was scored in DSS-treated miR-146a deficiency mice and their wild type (WT) littermates. Bulk RNA-sequencing, RT-qPCR and immunostaining were done to illustrate the downstream genetic regulatory networks of miR-146a in flamed colon. Finally, the modified miR-146a mimics were used to treat DSS-induced IBD in miR-146a knock-out and WT IBD mice. We showed that the expression of miR-146a in the colon was elevated in dextran sulfate sodium (DSS)-induced IBD mice and patients with IBD. DSS induced dramatic body weight loss and more significant rectal bleeding, shorter colon length, and colitis in miR-146a knock-out mice than WT mice. The miR-146a mimics alleviated DSS-induced symptoms in both miR-146a-/- and WT mice. Further RNA sequencing illustrated that the deficiency of miR-146a de-repressed majority of DSS-induced IBD-related genes that cover multiple genetic regulatory networks in IBD, and supplementation with miR-146a mimics inhibited the expression of many IBD-related genes. Quantitative RT-PCR or immunostaining confirmed that Ccl3, Saa3, Csf3, Lcn2, Serpine1, Serpine2, MMP3, MMP8, MMP10, IL1A, IL1B, IL6, CXCL2, CXCL3, S100A8, S100A9, TRAF6, P65, p-P65, and IRAK1 were regulated by miR-146a in DSS induced IBD. Among them, MMP3, MMP10, IL6, IL1B, S100A8, S100A9, SERPINE1, CSF3, and IL1A were involved in the active stage of IBD in humans. Our date demonstrated that miR-146a acts as a top regulator in C57/BL6N mice to systematically repress multiple genetic regulatory networks involved in immune response of intestine to environment factors, and combinatory treatment with miR-146a-5p and miR-146a-3p mimics attenuates DSS-induced IBD in mice through down-regulating multiple genetic regulatory networks which were increased in colon tissue from IBD patients. Our findings suggests that miR-146a is a top inhibitor of IBD, and that miR-146a-5p and miR-146a-3p mimics might be potential drug for IBD.

Evaluation of enrofloxacin in the Chinese soft-shelled turtle (Pelodiscus sinensis) based on the biochemical, histopathological and intestinal microbiota responses

Enrofloxacin (ENR) is a veterinary medicine extensively used in aquatic farming, the abuses of antibacterials can lead to drug residues and toxicity to aquatic animals. Nevertheless, its toxicological effects on the Pelodiscus sinensis remain unclear. The objective of this work was to study the toxic effects of ENR on male P. sinensis following multiple oral administration. For hematological, antioxidant status, histological and ultrastructural analyzed, male P. sinensis were orally administrated with ENR for 5 consecutive days, each at the dose of 15 (recommended dose, 1×), 45 (3 times the recommended dose, 3×), and 75 (5 times the recommended dose, 5×) mg/kg body weight (BW) daily. The effect of ENR on P. sinensis by changes in the intestinal microbiota using high-throughput sequencing technology was also investigated. Samples of blood and fresh tissue (liver, spleen, intestine, muscle, spermary, testes, heart, lung, and kidney) were collected after 24 h of drug withdrawal. The results showed that multiple oral administration of ENR induced immunosuppression (lowered total proteins, alkaline phosphatase, and albumin), hepatic-renal dysfunction (elevated aspartate transaminase, alanine aminotransferase, urea nitrogen, K+ and Ca2+), and lowering the hepatic and splenic antioxidant functions (higher MDA, and declines in the activities of SOD, CAT, and NOS) in 3× ENR-dosed or 5× ENR-dosed groups. Noteworthy, histopathological and ultrastructural examination of tissue samples revealed adverse effects with increasing oral dosage of ENR. The 16S sequencing analysis showed that the ENR treatment can greatly change the intestinal microbial diversity and abundance in P. sinensis, but more probiotics such as Cetobacterium, Lactococcus, and Paraclostridium were retained in the short-term period. The findings may provide new insights into the toxicity of ENR to P. sinensis, and help to determine the dose to ensure the safety of aquatic food products.

Analysis of intestinal epithelial cell responses to Cryptosporidium highlights the temporal effects of IFN-γ on parasite restriction.

The production of IFN-γ is crucial for control of multiple enteric infections, but its impact on intestinal epithelial cells (IEC) is not well understood. Cryptosporidium parasites exclusively infect epithelial cells and the ability of interferons to activate the transcription factor STAT1 in IEC is required for parasite clearance. Here, the use of single cell RNA sequencing to profile IEC during infection revealed an increased proportion of mid-villus enterocytes during infection and induction of IFN-γ-dependent gene signatures that was comparable between uninfected and infected cells. These analyses were complemented by in vivo studies, which demonstrated that IEC expression of the IFN-γ receptor was required for parasite control. Unexpectedly, treatment of Ifng-/- mice with IFN-γ showed the IEC response to this cytokine correlates with a delayed reduction in parasite burden but did not affect parasite development. These data sets provide insight into the impact of IFN-γ on IEC and suggest a model in which IFN-γ signalling to uninfected enterocytes is important for control of Cryptosporidium.

Metabolomics and microbiome co-analysis reveals altered innate immune responses in Charybdis japonica following Aeromonas hydrophila infection

A comprehensive bioinformatics analysis was conducted to elucidate the innate immune response of Charybdis japonica following exposure to Aeromonas hydrophila. This study integrated metabolomics, 16S rRNA sequencing, and enzymatic activity data to dissect the immune mechanisms activated in response to infection. Infection with A. hydrophila resulted in an increased abundance of beneficial intestinal genera such as Photobacterium spp., Rhodobacter spp., Polaribacter spp., Psychrilyobacter spp., and Mesoflavibacter spp. These probiotics appear to suppress A. hydrophila colonization by competitively dominating the intestinal microbiota. Key metabolic pathways affected included fatty acid biosynthesis, galactose metabolism, and nitrogen metabolism, highlighting their role in the crab's intestinal response. Enzymatic analysis revealed a decrease in activities of hexokinase, phosphofructokinase, and pyruvate kinase, which are essential for energy homeostasis and ATP production necessary for stress responses. Additionally, reductions were observed in the activities of acetyl-CoA carboxylase and fatty acid synthase. Gene expression analysis showed downregulation in Peroxiredoxin 1 (PRDX1), Peroxiredoxin 2 (PRDX2), glutathione-S-transferase (GST), catalase (CAT), and glutathione (GSH), with concurrent increases in malondialdehyde (MDA) levels, indicating severe oxidative stress. This study provides insights into the molecular strategies employed by marine crabs to counteract bacterial invasions in their natural habitat.

Paneth Cell TCF4 Deficiency Alters Gut Microbiota and Host Tissue Gene Expression

Introduction: The mucosal immune system is crucial in regulating gut microbiota composition. Paneth cells, the specialized secretory cells in the small intestine, produce α-defensins that regulate gut microbiota. The Wnt signaling pathway with T-cell factor-4 (TCF4) as the terminal signaling molecule regulates Paneth cell differentiation and function. Wnt signaling plays a role in Paneth cell α-defensin expression. TCF4 binds to the α-defensin promoter and increases the transcriptional activity. In this study, we investigated the role of Paneth cell TCF4 in regulating gut microbiota and the host intestinal gene expression. Materials and methods: We generated the Paneth cell-specific TCF4 knockout mice by crossing Tcf4flox/flox mice with the Defa6Cre mice. Tcf4flox/flox-Defa6Cre (KO) were compared with Tcf4flox/flox and Defa6Cre mice (WT). Colonic flushing from these mice was subjected to metatranscriptomics, metagenomics, and proteomics. Colonic tissue was analyzed for transcriptomics. Plasma lipopolysaccharide (LPS) was measured to evaluate endotoxemia. Intestinal mucosal inflammatory response and Paneth cell function were assessed by RT-PCR for cytokines, defensins, and lysozyme. Bioinformatics was applied to assess the taxonomic diversity and functional activity of the gut microbiome, colonic luminal peptides, and colonic mucosal gene expression. Results: The metatranscriptome profile of colonic contents showed an altered microbial diversity in KO mice compared to WT mice. PCoA analyses indicated that the microbial composition in the three strains was distinctly different from each other. At the phylum level, Proteobacteria and viruses such as Pisuviricota, Cressdnaviricota, and Artiverviricota were higher in KO mice than in WT mice. LEfSe analyses showed that the abundance of numerous bacterial and viral populations, such as Firmicutes, Clostridia, and Geminiviridae, was high in KO mice. Functional profiling further confirmed the alteration of microbial diversity in the KO mice. The increased abundance of bacteria in KO mice was related to human diseases, infectious diseases, and bacterial toxin production. Proteomic analyses indicated that nearly 36% of proteins identified in the KO mice were significantly altered compared to WT mice. The Reactome analyses indicated that the altered proteins in the KO mice were related to the immune system, cell cycle, cell signaling, and protein metabolism. RT-PCR of intestinal tissue showed that the expression of Defa6, lysozyme, and Reg3γ was low in KO mice compared to WT mice. On the other hand, the expression of IL-1β, IL-6, and MCP1 in the intestine was higher in KO mice compared to WT mice. These changes in microbiota and mucosa in the KO mice were associated with increased plasma LPS. Finally, there was a significant sex-dependent differences in the Paneth TCF4 activity on gut microbiota, intestinal gene expression and endotoxemia. Conclusion: This study indicates that the Paneth cell TCF4 is essential in regulating the gut microbial composition and host intestinal gene expression. NIH/NIAID, UO1-AI170019 and U01-AI172991. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Cucurbitacin E Alleviates Colonic Barrier Function Impairment and Inflammation Response and Improves Microbial Composition on Experimental Colitis Models.

Cucurbitacins, which are found in a variety of medicinal plants, vegetables and fruits, were known for their diverse pharmacological and biological activities, including anticancer, anti-oxidative and anti-inflammatory effects. Cucurbitacin E, one of the major cucurbitacins, was recently proved to inhibit inflammatory response. To explore the therapeutic effects of cucurbitacin E on colitis and the underlying mechanisms, male mice drunk water containing 2.5% dextran sulfate sodium (DSS) to establish colitis model and administrated with cucurbitacin E during and after DSS treatment. The disease activity index was scored and colonic histological damage was observed. Intestinal tight junction and inflammatory response were determined. 16S rRNA and transcriptome sequencing were performed to analyze gut microbiota composition and gene expression, respectively. We found that cucurbitacin E alleviated DSS-induced body weight loss and impaired colonic morphology. Cucurbitacin E decreased the expression of inflammatory cytokines and cell apoptosis, and maintained barrier function. Additionally, cucurbitacin E retrieved DSS-induced alterations in the bacterial community composition. Furthermore, a variety of differentially expressed genes (DEGs) caused by cucurbitacin E were enriched in several pathways including the NFκB and TNF signaling pathways as well as in Th17 cell differentiation. There was a close relationship between DEGs and bacteria such as Escherichia-Shigella and Muribaculaceae. Our results revealed that cucurbitacin E may exert protective effects on colitis via modulating inflammatory response, microbiota composition and host gene expression. Our study supports the therapeutic potential of cucurbitacin E in colitis and indicates that gut microbes are potentially therapeutic targets.

Long-term intermittent fasting induces sex-dependent changes in small intestine from SAMP8 aged mice

Background: Intermittent fasting (IF) is a popular and effective method to decrease body weight. Yet, the effects of IF on aged intestine is unknown. SAMP8 (Senescence Accelerated Mouse-Prone 8) mice are used as a model for studying aging. This study aimed to examine the potential for IF to ameliorate age-associated disturbances in murine jejunum. Methods: Two-month-old male and female SAMP8 mice were randomly assigned to either an IF protocol or an ad-libitum diet (AL) for the 8-month study (n=7-10 group). Fasted mice followed a 24-hour alternate day fasting protocol. At the end of the study mice were euthanized and jejunum stored at −80°C until use for western blot or other assay, and a segment was fixed for histology. Results: IF resulted in significantly less weight gain in both males (22% less, n=7-10, p<0.05) and females (33% less, n=7-8, p<0.05) and response to glucose load (glucose tolerance testing) was comparable in both sexes: area under curve for AL > IF. Interestingly, IF significantly reduced fasting serum glucose levels in males (30% less, n=6, p<0.05), but IF had no effect on fasting serum glucose in females. In jejunum, we assessed: protein expression, health, and morphology. In females, IF led to a 57% decrease in GLUT2 expression (n=5-6, p<0.05) versus AL. GLUT2 moves glucose/galactose and fructose out of the enterocyte into the blood, suggesting restructuring of monosaccharide transport due to IF. IF had no effect on jejunum GLUT5 or SGLT1 expression. Cleaved Caspase-3 expression was decreased by IF in both sexes versus AL. This reduction was greater in females, suggesting a sex-dependent protective role of IF against apoptosis. Moreover, IF induced a significant increase 1.4-fold (n=5=6, p<0.05) in jejunum superoxide dismutase (SOD) activity in both sexes. Jejunum morphology was significantly changed in females only: IF induced both a decrease in villi length (by 21%, n=4/group, p<0.05) and a decrease in wall thickness (by 7%, n=4/group, p<0.05). Conclusions: In both sexes, IF decreased body weight, yet in females resting glucose levels were unchanged by IF. In females, IF reduced monosaccharide absorption out of intestines, yet improved overall intestinal health, increasing antioxidant levels with SOD. These findings collectively highlight the complex effects of IF on cellular processes and demonstrate significant sex-dependent aged intestinal responses. Unraveling the underlying molecular mechanisms driving these sex-dependent IF-induced effects is currently under evaluation. Midwestern-Arizona Alzheimer’s Consortium Grant, Midwestern University Intramural Grant. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Transcriptomic analyses provide new insights into immune response of the Procambarus clarkii intestines to Aeromonas hydrophila challenge

In recent years, the death rate of Procambarus clarkii increased sharply due to pathogenic bacterial infections, leading to huge economic losses. To determine the immune response of the intestinal tissues of P. clarkii to bacterial infections, we compared the immune indexes, histopathological damage, and transcriptome data of the control and Aeromonas hydrophila-infected P. clarkii. With the injection of A. hydrophila, it was found that intestinal mucosal folds increased, intestinal villi showed obvious vacuolation, and the tissue structure changed significantly. The results of non-specific immunoenzyme activity showed that the Total protein (TP) content was significantly lower than that of the control group at 24 h, and the Acid phosphatase (ACP) and Alkaline phosphatase (AKP) activities in the treatment group showed a significant increasing trend (p < 0.05). In terms of the transcriptome, an average of 22,927,523 clean reads and 27,866 genes were found in the control and treatment groups through gene assembly and annotation. Among these genes, 567 were identified as differentially expressed genes (DEGs), of which 501 were up-regulated and 66 were down-regulated. Quantitative-polymerase chain reaction (qPCR) analysis of six randomly selected genes was used to verify the RNA-sequencing results. The Gene Ontology enrichment analysis revealed that the DEGs were primarily involved in cell processes, metabolic processes, and biological regulation, while the Kyoto Encyclopedia of Genes and Genomes enrichment analysis showed that these DEGs were involved in tyrosine metabolism, glycosphingolipid biosynthesis—ganglionic series, and nitrogen metabolism. We studied the tyrosine metabolic pathway and found that it contributes to the immune defense mechanism of P. clarkii. The results of our study provide important insights into the intestinal immune response of P. clarkii to A. hydrophila infection.

Ruscogenin Attenuates Ulcerative Colitis in Mice by Inhibiting Caspase-1-Dependent Pyroptosis via the TLR4/NF-κB Signaling Pathway.

Inflammatory bowel diseases (IBD) are chronic inflammatory disorders affecting the digestive tract, including ulcerative colitis and Crohn's disease. Ruscogenin, a prominent steroidal sapogenin present in radix ophiopogon japonicus, has shown a protective effect on attenuating the inflammatory response associated with inflammatory diseases, but the efficacy of ruscogenin in IBD remains unclear. The aim of this study is to explore the effect of ruscogenin on intestinal barrier dysfunction and inflammatory responses as well as the underlying mechanism in ulcerative colitis. A dextran sulfate sodium salt (DSS)-induced C57BL/6 mouse colitis model was employed for the in vivo studies, while in vitro experiments were performed in THP-1 cells and human intestinal epithelial cells involved in inducing inflammatory responses and pyroptosis using LPS/nigericin. The results indicated that ruscogenin treatment attenuated the symptoms of ulcerative colitis, reduced the release of inflammatory cytokines and the expression of pyroptosis-associated proteins, and restored the integrity of the intestinal epithelial barrier in colon tissue in mice. Moreover, ruscogenin inhibited LPS/nigericin-induced pyroptosis in THP-1 cells. Mechanically, ruscogenin inhibited NLRP3 inflammasome activation and canonical pyroptosis, at least in part, through the suppression of the TLR4/NF-κB signaling pathway. These findings might provide new insights and a solid foundation for further exploration into the therapeutic potential of ruscogenin in the treatment of IBD.

Effects of feeding chicken egg yolk antibodies on intestinal cell apoptosis, oxidative stress and microbial flora of tilapia (Oreochromis niloticus) infected with Streptococcus agalactiae

Streptococcosis, the most common bacterial disease of fish in recent years, is highly infectious and lethal, and has become an important factor hindering the healthy and sustainable development of aquaculture. Chicken egg yolk antibody (IgY) has the advantages of high antigen specificity, inexpensive and easy to obtain, simple preparation, no toxic side effects, and in line with animal welfare, which is a green and safe alternative to antibiotics. In this study, the potential of specific IgY in the treatment of gastrointestinal pathogens was explored by observing the effects of specific IgY on intestinal flora, pathological tissue, apoptosis, oxidative stress, and inflammatory response of tilapia. We used the specific IgY prepared in the early stage to feed tilapia for 10 days, and then the tilapia was challenged with Streptococcus agalactiae. The results showed that feeding IgY before challenge had a small effect on the intestinal flora, and after challenge specific IgY decreased the proportion of Streptococcus and increased the diversity of the intestinal flora; in histopathology, specific IgY decreased tissue damage and maintained the integrity of tissue structure.Further study found that specific IgY can reduce intestinal epithelial cell apoptosis and reduce caspase activity; at the same time, the content of MDA was decreased, and the activities of SOD, CAT, GSH-Px and GR were increased. In addition, specific IgY can down-regulate the expression levels of IL-8 and TNF-α genes and up-regulate the expression levels of IL-10 and TGF-β. The results of this study showed that specific IgY could improve the intestinal flora of tilapia infected with Streptococcus agalactiae, reduce intestinal cell apoptosis, oxidative stress injury and inflammatory response, thereby reducing tissue damage and protecting the health of tilapia. Overall, specific IgY can be further explored as a potential antibiotic alternative for gastrointestinal pathogen infections.

Transport of glycinin, the major soybean allergen, across intestinal epithelial IPEC-J2 cell monolayers.

Soybean allergen entering the body is the initial step to trigger intestinal allergic response. However, it remains unclear how glycinin, the major soybean allergen, is transported through the intestinal mucosal barrier. The objective of this study was to elucidate the pathway and mechanism of glycinin hydrolysatetransport through the intestinal epithelial barrier using IPEC-J2 cell model. Purified glycinin was digested by in vitro static digestion model. The pathway and mechanism of glycinin hydrolysates transport through intestinal epithelial cells were investigated by cellular transcytosis assay, cellular uptake assay, immunoelectron microscopy and endocytosis inhibition assay. The glycinin hydrolysates were transported across IPEC-J2 cell monolayers in a time/dose-dependent manner following the Michaelis equation. Immunoelectron microscopy showed a number of glycinin hydrolysates appeared in the cytoplasm, but no glycinin hydrolysates were observed in the intercellular space of IPEC-J2 cells. The inhibitors, colchicine, chlorpromazine and methyl-β-cyclodextrin,significantly inhibited the cellular uptake of glycinin hydrolysates. The glycinin hydrolysates crossed IPEC-J2 cell monolayers through the transcellular pathway. Both clathrin- and caveolae-dependent endocytosis were involved in the epithelial uptake of the hydrolysates. These findings provided potential targets for the prevention and treatment of soybean allergy.

Sclareol protected against intestinal barrier dysfunction ameliorating Crohn's disease-like colitis via Nrf2/NF-B/MLCK signalling

BackgroundInflammation-induced intestinal barrier dysfunction is not only a pathological feature of Crohn's disease (CD) but also an important therapeutic target. Sclareol (SCL) is a nontoxic natural plant compound with anti-inflammatory effect, but its role in CD has not been established. MethodsIn vivo studies of mice with TNBS-induced colitis were carried out to evaluate the effects of SCL on CD-like colitis and intestinal barrier function. In vitro, a TNF-α-induced colonic organoid model was established to test the direct effect of SCL on inflammation-induced intestinal barrier injure and inflammatory response. The Nrf2/NF-κB/MLCK signalling was analysed to explore the mechanism of SCL. ResultsIn vivo, SCL largely alleviated the colitis in TNBS mice, as evidenced by improvements in the weight loss, colitis symptoms, endoscopic score, macroscopic histological score, and histological inflammation score. Moreover, SCL significantly improved intestinal barrier dysfunction, manifested as reduced intestinal permeability and decreased intestinal bacterial translocation in TNBS mice. Importantly, SCL antagonised the intestinal mucosal inflammation while protecting tight junctions in TNBS mice. In vitro, SCL largely depressed pro-inflammatory cytokines levels and improved intestinal epithelial permeability in a TNF-α-induced colonic organoid model. In the context of CD, the protective effects of SCL against inflammation and intestinal barrier damage are at least partially results from the Nrf2 signalling activation and the NF-κB/MLCK signalling inhibition. ConclusionsSCL improved intestinal barrier dysfunction and alleviated CD-like colitis, possibly through modulation of Nrf2/NF-κB/MLCK signalling. In view of SCL's safety profile, there is hope that it will be useful in the clinic.