Expression, Distribution and Role of Aquaporin Water Channels in Human and Animal Stomach and Intestines

Study on the Effect and Mechanism of Weichang'an Pill and Its Extract on Slow Transit Constipation

BACKGROUND

Weichang'an pill (WCA) possesses potential advantages in promoting gastrointestinal motility and treating constipation. Ethanol extract (EE) and aqueous extract (AE) of WCA were used to investigate its efficacy in treating slow transit constipation (STC) and the material basis for exerting this effect.

METHODS

The STC model was established in vivo by gavage of loperamide (Lop) in Sprague-Dawley rats, followed by gavage of WCA, EE, and AE. In vitro, norepinephrine (NE) was used to stimulate isolated ileal smooth muscle of rats to imitate the state of insufficient gastrointestinal motility during STC, and a model of excessive relaxation of isolated ileal smooth muscle was established. This model was used to observe and record the changes in contraction tension, amplitude, and frequency of ileal smooth muscle after treatment with WCA, EE, AE, and the active ingredients of WCA.

KEY RESULTS

In vivo, WCA, EE, and AE treatment increased fecal parameters, improved gastrointestinal transit time, and alleviated pathological damage to the colon in STC rats. Its mechanism might be closely related to c-kit/SCF, RhoA/ROCK/MYPT1/MLC signaling pathways. In vitro, WCA, EE, AE, and the active ingredients of WCA, including costunolide (Cos), dehydrocostus lactone (Deh), agarotetrol (Aga), muscone (Mus), gallic acid (GA), oleic acid (Oleic), linoleic acid (Lin), umbelliferone (Umb), synephrine (Syn), ferulic acid (FA), chlorogenic acid (ChA), betaine (Bet), and riboflavin (Rib), significantly inhibited the NE-induced excessive relaxation of ileal smooth muscles.

CONCLUSIONS

WCA, EE, and AE significantly improved constipation in STC rats. Moreover, the active ingredients in WCA, including Cos, Deh, Aga, Mus, GA, Oleic, Lin, Umb, Syn, FA, ChA, Bet, and Rib, might be the material basis for promoting intestinal motility.

Impact of sodium butyrate on stroke-related intestinal injury in diabetic mice: Interference with Caspase-1/GSDMD pyroptosis pathway and preservation of intestinal barrier

Diabetic stroke-associated acute intestinal injury is characterized by high mortality, disability, and poor prognosis due to the lack of effective therapies. Our prior research demonstrated that administration of 300 mg/kg sodium butyrate (NaB) can improve neurological outcomes post-diabetic stroke. Nonetheless, whether the effect of NaB is related to intestinal regulation, along with its underlying mechanisms, remains uncertain. This study aims to investigate the effects and mechanistic pathways of NaB on diabetic stroke-associated acute intestinal injury. A middle cerebral artery occlusion/reperfusion model was established in mice with streptozotocin-induced diabetes. The results demonstrated that NaB alleviated colonic injury 24 h after reperfusion in diabetic stroke. Pyroptosis-related protein levels in colonic tissues were significantly elevated following diabetic stroke but were markedly reduced with NaB treatment. NaB also improved gut barrier integrity and reduced inflammation, promoting epithelial barrier self-repair. In the NaB combined with lipopolysaccharide group, lipopolysaccharide administration induced a significant inflammatory response in the colonic tissue. Conversely, treatment with NaB and VX-765 (an inhibitor for Caspase-1) led to a notable alleviation in intestinal inflammation. These findings suggest that NaB mitigates colonic injury and enhances barrier function following diabetic stroke, potentially through the Caspase-1/Gasdermin D pyroptosis pathway. This study may provide a novel strategy and direction for intestinal rehabilitation in diabetic stroke patients.

Low molecular weight galactomannan alleviates diarrhea induced by senna leaf in mice via intestinal barrier improvement and gut microbiota modulation

Low molecular weight galactomannan (LMGM), a soluble dietary fibre derived from guar gum, is recognized for its prebiotic functions, including promoting the growth of beneficial intestinal bacteria and the production of short-chain fatty acids, but the mechanism of alleviating diarrhea is not fully understood. This study established an acute diarrhea mouse model using senna leaf decoction and evaluated the therapeutic effects of LMGM by monitoring diarrhea scores, loose stool prevalence, intestinal tissue pathology and gene expression, and gut microbiota composition and metabolisms. The results indicated that LMGM significantly reduced diarrhea scores and loose stool prevalence within two hours post-treatment. Hematoxylin and eosin staining and quantitative real-time polymerase chain reaction analysis revealed that LMGM improved intestinal epithelial structure and up-regulated the expression of zonula occludens 1, occludin, mucin 2, aquaporin 3, and aquaporin 4 in ileum, jejunum, and colon tissues. Moreover, LMGM increased the abundance of beneficial bacteria such as Lactobacillaceae and Lachnospiraceae, and decreased Prevotellaceae in the cecum. Furthermore, LMGM promoted short-chain fatty acid production and reduced ammonia nitrogen and skatole concentrations in the intestinal content. The study suggests that LMGM could serve as a functional prebiotic for diarrhea alleviation, potentially by enhancing the intestinal barrier, modulating water transportation, and regulating the microbiota composition.

Cryptosporidium parvum infection alters the intestinal mucosa transcriptome in neonatal calves: impacts on epithelial barriers and transcellular transport systems

Introduction

Cryptosporidium parvum (C. parvum) is the most prevalent enteric protozoan parasite causing infectious diarrhea in neonatal calves worldwide with a direct negative impact on their health and welfare. This study utilized next-generation sequencing (NGS) to deepen our understanding of intestinal epithelial barriers and transport mechanisms in the pathophysiology of infectious diarrhea in neonatal calves, which could potentially unveil novel solutions for treatment.

Methods

At day 1 of life, male Holstein-Friesian calves were either orally infected (n = 5) or not (control group, n = 5) with C. parvum oocysts (in-house strain LE-01-Cp-15). On day 8 after infection, calves were slaughtered and jejunum mucosa samples were taken. The RNA was extracted from collected samples and subjected to sequencing. Differentially expressed genes (DEG) between the infected and CTRL groups were assessed using DESeq2 at a false discovery rate < 0.05 and used for gene ontology (GO) and pathway enrichment analysis in Cytoscape (v3.9.1).

Results and discussion

To study the pathophysiology of infectious diarrhea on intestinal permeability, 459 genes related to epithelial cell barrier integrity and paracellular and transmembrane transport systems were selected from 12,908 identified genes in mucus. Among, there were 61 increased and 109 decreased gene transcripts belonged to adhesion molecules (e.g. ADGRD1 and VCAM1), ATP-binding cassette (ABC, e.g. ABCC2 and ABCD1) and solute carrier (SLC, e.g. SLC28A2 and SLC38A3) transporters, and ion channels (e.g. KCNJ15). Our results suggest deregulation of cellular junctions and thus a possibly increased intestinal permeability, whereas deregulation of ABC and SLC transporters and ion channels may influence the absorption/secretion of amino acids, carbohydrates, fats, and organic compounds, as well as acid-based balance and osmotic hemostasis. Besides pathogen-induced gene expression alterations, part of the DEG may have been triggered or consequently affected by inflammatory mechanisms. The study provided a deeper understanding of the pathophysiology of infectious diarrhea in neonatal calves and the host-pathogen interactions at the transcript level. For further studies with a particular focus on the transport system, these results could lead to a new approach to elucidating pathophysiological regulatory mechanisms.

Aquaporin proteins: A promising frontier for therapeutic intervention in cerebral ischemic injury

Cerebral ischemic injury is characterized by reduced blood flow to the brain, remains a significant cause of morbidity and mortality worldwide. Despite improvements in therapeutic approaches, there is an urgent need to identify new targets to lessen the effects of ischemic stroke. Aquaporins, a family of water channel proteins, have recently come to light as promising candidates for therapeutic intervention in cerebral ischemic injury. There are 13 aquaporins identified, and AQP4 has been thoroughly involved with cerebral ischemia as it has been reported that modulation of AQP4 activity can offers a possible pathway for therapeutic intervention along with their role in pH, osmosis, ions, and the blood-brain barrier (BBB) as possible therapeutic targets for cerebral ischemia injury. The molecular pathways which can interacts with particular cellular pathways, participation in neuroinflammation, and possible interaction with additional proteins thought to be involved in the etiology of a stroke. Understanding these pathways offers crucial information on the diverse role of AQPs in cerebral ischemia, paving the door for the development of focused/targeted therapeutics.

Important functions and molecular mechanisms of aquaporins family on respiratory diseases: potential translational values

Aquaporins (AQPs) are a subgroup of small transmembrane transporters that are distributed in various types of tissues, including the lung, kidney, heart and central nervous system. It is evident that respiratory diseases represent a significant global health concern, with a considerable number of deaths occurring worldwide. Recent researches have demonstrated that AQPs play a pivotal role in respiratory diseases, including chronic obstructive pulmonary disease (COPD), asthma, acute respiratory distress syndrome (ARDS), and particularly non-small cell lung cancer (NSCLC). In the context of NSCLC, the overexpression of AQP1, AQP3, AQP4, and AQP5 has been demonstrated to facilitate tumor angiogenesis, as well as the proliferation, migration, and invasiveness of tumor cells. This review concisely explores the role of AQP family on respiratory diseases, to assess their clinical and translational significance for understanding molecular pathogenesis. However, the potential translation of AQPs biomarkers into clinical applications is promising and the understanding of the precise mechanisms influencing respiratory diseases is still ongoing. Addressing the challenges and outlining the future perspectives in AQPs development is essential for clinical progress in a concise manner.

Golden Flower Tibetan Tea Polysaccharides Alleviate Constipation in Mice by Regulating Aquaporins-Mediated Water Transport System and Gut Microbiota

Constipation, a widespread gastrointestinal disorder, often leads to the exploration of natural remedies. This study examines the efficacy of Golden Flower Tibetan Tea Polysaccharides (GFTTPs) in alleviating constipation in mice. Chemical analyses reveal that GFTTPs possess O-H, carboxyl, carboxylic acid (-COOH), and C-O-C groups, alongside a porous crystal structure with thermal stability. In animal experiments, GFTTPs significantly upregulated aquaporin 3 (AQP3) and aquaporin 8 (AQP8) expressions in the colon, enhancing water absorption and reducing fecal water content. At a 400 mg/kg dosage, GFTTPs notably improved colonic tissue alterations and serum levels of excitatory neurotransmitters caused by loperamide hydrochloride. They also beneficially altered gut microbiota, increasing Coprococcus, Lactobacillus, and Pediococcus populations. These changes correlated with improved stool frequency, consistency, and weight in constipated mice. Importantly, GFTTPs at 200 and 400 mg/kg doses exhibited comparable effects to the normal control group in key parameters, such as gastrointestinal transit rate and fecal moisture. These findings suggest that GFTTPs may serve as a potent natural remedy for constipation, offering significant therapeutic potential within the context of gut health and with promising implications for human applications.

Kidney-tonifying blood-activating decoction delays ventricular remodeling in rats with chronic heart failure by regulating gut microbiota and metabolites and p38 mitogen-activated protein kinase/p65 nuclear factor kappa-B/aquaporin-4 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Myocardial infarction has likely contributed to the increased prevalence of heart failure(HF).As a result of ventricular remodeling and reduced cardiac function, colonic blood flow decreases, causing mucosal ischemia and hypoxia of the villous structure of the intestinal wall.This damage in gut barrier function increases bowel wall permeability, leading to fluid metabolism disorder,gut microbial dysbiosis, increased gut bacteria translocation into the circulatory system and increased circulating endotoxins, thus promoting a typical inflammatory state.Traditional Chinese Medicine plays a key role in the prevention and treatment of HF.Kidney-tonifying Blood-activating(KTBA) decoction has been proved for clinical treatment of chronic HF.However,the mechanism of KTBA decoction on chronic HF is still unclear.

AIMS OF THE STUDY

The effect of KTBA decoction on gut microbiota and metabolites and p38MAPK/p65NF-κB/AQP4 signaling in rat colon was studied to investigate the mechanism that KTBA decoction delays ventricular remodeling and regulates water metabolism disorder in rats with HF after myocardial infarction based on the theory of "Kidney Storing Essence and Conducting Water".

MATERIAL AND METHODS

In vivo,a rat model of HF after myocardial infarction was prepared by ligating the left anterior descending coronary artery combined with exhaustive swimming and starvation.The successful modeling rats were randomly divided into five groups:model group, tolvaptan group(gavaged 1.35mg/(kg•D) tolvaptan),KTBA decoction group(gavaged 15.75g/(kg•D) of KTBA decoction),KTBA decoction combined with SB203580(p38MAPK inhibitor) group(gavaged 15.75g/(kg•D) of KTBA decoction and intraperitoneally injected 1.5mg/(kg•D) of SB203580),and KTBA decoction combined with PDTC(p65NF-kB inhibitor) group(gavaged 15.75g/(kg•D) of KTBA decoction and intraperitoneally injected 120mg/(kg•D) of PDTC).The sham-operation group and model group were gavaged equal volume of normal saline.After 4 weeks of intervention with KTBA decoction,the effect of KTBA decoction on the cardiac structure and function of chronic HF model rats was observed by ultrasonic cardiogram.General state and cardiac index in rats were evaluated.Enzyme linked immunosorbent assay(ELISA) was used to measure N-terminal pro-brain natriuretic peptide (NT-proBNP) concentration in rat serum.Hematoxylin and eosin(H&E) staining,and transmission electron microscope(TEM) were used to observe the morphology and ultrastructure of myocardial and colonic tissue,and myocardial fibrosis was measured by Masson's staining.Cardiac E-cadherin level was detected by Western blot.The mRNA expression and protein expression levels of p38MAPK,I-κBα, p65NF-κB,AQP4,Occludin and ZO-1 in colonic tissue were detected by reverse transcription-quantitative real-time polymerase chain reaction(RT-qPCR) and immunohistochemistry. Protein expression of p38MAPK, p-p38MAPK,I-κBα,p-I-κBα,p65NF-κB, p-p65NF-κB,AQP4,Occludin and ZO-1 in rat colon was detected using Western blot.Colonic microbiota and serum metabolites were respectively analyzed by amplicon sequencing and liquid chromatography-mass spectrometry.In vitro, CCD-841CoN cell was placed in the ischemic solution under hypoxic conditions (94%N2,5%CO2,and 1%O2) in a 37 °C incubator to establish an ischemia and hypoxia model.The CCD-841CoN cells were divided into 7 groups, namely blank group and model group with normal rat serum plus control siRNA, tolvaptan group with rat serum containing tolvaptan plus control siRNA, KTBA group with rat serum containing KTBA plus control siRNA, KTBA plus p38MAPK siRNA group, KTBA plus p65NF-κB siRNA group,and KTBA plus AQP4siRNA group.After 24h and 48h of intervention with KTBA decoction,RT-qPCR,immunofluorescence and Western blot was used to detect the mRNA expression and protein expression levels of p38MAPK,I-κBα,p65NF-κB,AQP4, Occludin and ZO-1 in CCD-841CoN cells.

RESULTS

Compared with the model, KTBA decoction improved the general state, decraesed the serum NT-proBNP level,HW/BW ratio, LVIDd and LVIDs, increased E-cadherin level,EF and FS,reduced number of collagen fibers deposited in the myocardial interstitium,and recovered irregular arrangement of myofibril and swollen or vacuolated mitochondria with broken crista in myocardium.Moreover, KTBA decoction inhibited the expression of p38MAPK,I-κBα,and p65NF-κB and upregulated AQP4, Occludin and ZO-1 in colon tissues and CCD-841CoN cells.Additionally,p38siRNA or SB203580, p65siRNA or PDTC, and AQP4siRNA partially weakened the protective effects of KTBA in vitro and vivo.Notably,The LEfSe analysis results showed that there were six gut biomaker bacteria in model group, including Allobaculum, Bacillales,Turicibacter, Turicibacterales,Turicibacteraceae,and Bacilli. Besides, three gut biomaker bacteria containing Deltaproteobacteria, Desulfovibrionaceae,and Desulfovibrionales were enriched by KTBA treatment in chronic HF model.There were five differential metabolites, including L-Leucine,Pelargonic acid, Capsidiol,beta-Carotene,and L- Erythrulose, which can be regulated back in the same changed metabolic routes by the intervention of KTBA.L-Leucine had the positive correlation with Bacillales, Turicibacterales,Turicibacteraceae,and Turicibacter.L-Leucine significantly impacts Protein digestion and absorption, Mineral absorption,and Central carbon metabolism in cancer regulated by KTBA, which is involved in the expression of MAPK and tight junction in intestinal epithelial cells.

CONCLUSIONS

KTBA decoction manipulates the expression of several key proteins in the p38MAPK/p65NF-κB/AQP4 signaling pathway, modulates gut microbiota and metabolites toward a more favorable profile, improves gut barrier function, delays cardiomyocyte hypertrophy and fibrosis,and improves cardiac function.

AQP1 Deficiency Drives Phthalate-Induced Epithelial Barrier Disruption through Intestinal Inflammation

Di-2-ethylhexyl phthalate (DEHP) is frequently used as a plasticizer to enhance the plasticity and durability of agricultural products, which pose adverse effects to human health and the environment. Aquaporin 1 (AQP1) is a main water transport channel protein and is involved in the maintenance of intestinal integrity. However, the impact of DEHP exposure on gut health and its potential mechanisms remain elusive. Here, we determined that DEHP exposure induced a compromised duodenum structure, which was concomitant with mitochondrial structural injury of epithelial cells. Importantly, DEHP exposure caused duodenum inflammatory epithelial cell damage and strong inflammatory response accompanied by activating the TLR4/MyD88/NF-κB signaling pathway. Mechanistically, DEHP exposure directly inhibits the expression of AQP1 and thus leads to an inflammatory response, ultimately disrupting duodenum integrity and barrier function. Collectively, our findings uncover the role of AQP1 in phthalate-induced intestinal disorders, and AQP1 could be a promising therapeutic approach for treating patients with intestinal disorders or inflammatory diseases.

Gallic acid mitigates intestinal inflammation and loss of tight junction protein expression using a 2D-Caco-2 and RAW 264.7 co-culture model

A 2D-intestinal epithelial Caco-2/RAW 264.7 macrophage co-culture model was developed to demonstrate the relative efficacy of different phenolic acids to mitigate changes in Caco-2 epithelial cell redox state initiated both directly by autoxidation products, H2O2, and indirectly through cell communication events originating from cytokine stimulated macrophage. An inducer cocktail (lipopolysaccharide + interferon gamma) was used to activate RAW 264.7 cells in the 2D- Caco-2/RAW co-culture and intracellular changes in Caco-2 cell redox signaling occurred in response to positive changes (p < 0.05) in inflammatory biomarkers derived in macrophage that included IL-6, TNF-α, nitric oxide and peroxynitrite, respectively. Phenolic acids varied in relative capacity to reduce NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) in cocktail inflamed induced macrophage. This response in addition to the relative predisposition of gallic acid (GA) to undergo autoxidation to generate H2O2 activity (p < 0.05), culminated in downstream cell signaling in Caco-2 nuclear factor erythroid 2-related factor (Nrf2) activity (increase 26.9 %), altered monolayer integrity (increase 33.7 %), and release of interleukin 8 (IL-8) (decrease 80.5 %) (p < 0.05). It can be concluded that the co-culture model described herein was useful to assess the importance of communication between cytokine stimulated macrophage and intestinal cells. Moreover, the relative unique efficacy of GA, compared to other phenolic acids tested to protect against activated macrophage induced changes related to intestinal dysfunction were particularly relevant to epithelial redox signaling, intestinal permeability and regulation of tight junction proteins. This study concludes that phenolic acids are not equal in the capacity to protect against intestinal cell dysfunction despite some indication of biological activity.

Genetic adaptations for the oceanic success of fish eggs

Genetic adaptations of organisms living in extreme environments are fundamental to our understanding of where life can evolve. Water is the single limiting parameter in this regard, yet when released in the oceans, the single-celled eggs of marine bony fishes (teleosts) have no means of acquiring it. They are strongly hyposmotic to seawater and lack osmoregulatory systems. Paradoxically, modern teleosts successfully release vast quantities of eggs in the extreme saline environment and recorded the most explosive radiation in vertebrate history. Here, we highlight key genetic adaptations that evolved to solve this paradox by filling the pre-ovulated eggs with water. The degree of water acquisition is uniquely prevalent to marine teleosts, permitting the survival and oceanic dispersal of their eggs.

Dynamics and metabolic effects of intestinal gases in healthy humans

Many living beings use exogenous and/or endogenous gases to attain evolutionary benefits. We make a comprehensive assessment of one of the major gaseous reservoirs in the human body, i.e., the bowel, providing extensive data that may serve as reference for future studies. We assess the intestinal gases in healthy humans, including their volume, composition, source and local distribution in proximal as well as distal gut. We analyse each one of the most abundant intestinal gases including nitrogen, oxygen, nitric oxide, carbon dioxide, methane, hydrogen, hydrogen sulfide, sulfur dioxide and cyanide. For every gas, we describe diffusive patterns, active trans-barrier transport dynamics, chemical properties, intra-/extra-intestinal metabolic effects mediated by intracellular, extracellular, paracrine and distant actions. Further, we highlight the local and systemic roles of gasotransmitters, i.e., signalling gaseous molecules that can freely diffuse through the intestinal cellular membranes. Yet, we provide testable hypotheses concerning the still unknown effects of some intestinal gases on the myenteric and submucosal neurons.

Therapeutic effects of intermittent fasting on high-fat, high-fructose diet; involvement of jejunal aquaporin 1, 3, and 7

Background

Aquaporins (AQPs) are transmembrane channel proteins. Aquaporin 1 (AQP1), Aquaporin 3 (AQP3), and Aquaporin 7 (AQP7) are expressed in the jejunum. The purpose of this study was to ascertain how a high-fat high-fructose diet (HFFD) and intermittent fasting (IF) affect AQP1, AQP3, and AQP7 expression in the rat jejunum.

Methods

Sixteen adult male rats were divided into control rats (n = 4) fed on a basal diet and water ad libitum for 12 weeks; IF control rats (n = 4) followed the IF protocol, HFFD-fed rats (n = 8) fed HFFD for eight weeks, and rats were randomized into two groups: HFFD only or HFFD and IF protocol from the beginning of the 9th week until the end of the experiment. The lipid profile values were assessed after 12 weeks. Jejunal oxidative markers (malondialdehyde and reduced glutathione) and AQP1, AQP3, and AQP7 mRNA expression were measured. Jejunal sections were used for morphometric analysis of villus length and crypt depth. Immunohistochemical evaluation of AQP1, AQP3, and AQP7 expression was also performed.

Results

IF ameliorates HFFD-induced lipid profile, oxidative stress, and jejunal morphometric changes. The results of both mRNA expression using PCR and immunohistochemistry showed a significant increase in AQP1, AQP3, and AQP7 expression in HFFD, whereas IF caused a decline in this expression.

Conclusion

These findings suggest that IF can reduce inflammation, and oxidative stress and restore jejunal morphology caused by HFFD.

Anti-Inflammatory Effects of a Novel Acetonitrile-Water Extract of Lens Culinaris against LPS-Induced Damage in Caco-2 Cells

Natural compounds like flavonoids preserve intestinal mucosal integrity through their antioxidant, anti-inflammatory, and antimicrobial properties. Additionally, some flavonoids show prebiotic abilities, promoting the growth and activity of beneficial gut bacteria. This study investigates the protective impact of Lens culinaris extract (LE), which is abundant in flavonoids, on intestinal mucosal integrity during LPS-induced inflammation. Using Caco-2 cells as a model for the intestinal barrier, the study found that LE did not affect cell viability but played a cytoprotective role in the presence of LPS. LE improved transepithelial electrical resistance (TEER) and tight junction (TJ) protein levels, which are crucial for barrier integrity. It also countered the upregulation of pro-inflammatory genes TRPA1 and TRPV1 induced by LPS and reduced pro-inflammatory markers like TNF-α, NF-κB, IL-1β, and IL-8. Moreover, LE reversed the LPS-induced upregulation of AQP8 and TLR-4 expression. These findings emphasize the potential of natural compounds like LE to regulate the intestinal barrier and reduce inflammation's harmful effects on intestinal cells. More research is required to understand their mechanisms and explore therapeutic applications, especially for gastrointestinal inflammatory conditions.

Effect of Probiotics in Stress-Associated Constipation Model in Zebrafish (Danio rerio) Larvae

The pathophysiology of functional bowel disorders is complex, involving disruptions in gut motility, visceral hypersensitivity, gut-brain-microbiota interactions, and psychosocial factors. Light pollution, as an environmental stressor, has been associated with disruptions in circadian rhythms and the aggravation of stress-related conditions. In this study, we investigated the effects of environmental stress, particularly continuous light exposure, on intestinal motility and inflammation using zebrafish larvae as a model system. We also evaluated the efficacy of probiotics, specifically Bifidobacterium longum (B. longum), at alleviating stress-induced constipation. Our results showed that continuous light exposure in zebrafish larvae increased the cortisol levels and reduced the intestinal motility, establishing a stress-induced-constipation model. We observed increased inflammatory markers and decreased intestinal neural activity in response to stress. Furthermore, the expressions of aquaporins and vasoactive intestinal peptide, crucial for regulating water transport and intestinal motility, were altered in the light-induced constipation model. Administration of probiotics, specifically B. longum, ameliorated the stress-induced constipation by reducing the cortisol levels, modulating the intestinal inflammation, and restoring the intestinal motility and neural activity. These findings highlight the potential of probiotics to modulate the gut-brain axis and alleviate stress-induced constipation. Therefore, this study provides a valuable understanding of the complex interplay among environmental stressors, gut function, and potential therapeutic strategies.

Protective effects and mechanisms of ellagic acid on intestinal injury in piglets infected with porcine epidemic diarrhea virus

The present study was conducted to decipher the protection effects of ellagic acid (EA) on piglets infected with porcine epidemic diarrhea virus (PEDV). Thirty 7-day-old piglets were randomly assigned to three treatment groups: control, PEDV, and EA + PEDV groups. After a 3-day period of adaption, piglets in the EA + PEDV group were orally administered with 20 mg/kg·BW EA during days 4-11 of the trial. On day 8, piglets were orally administered with PEDV at a dose of 106 TCID50 (50% tissue culture infectious dose) per pig. Additionally, intestinal porcine epithelial (IPEC-1) cells infected with PEDV were used to investigate the anti-PEDV effect of EA in vitro. The results showed that EA at a dose of 10-40 μmol/L increased the viability of PEDV-infected IPEC-1 cells, and EA administration mitigated intestinal edema in piglets challenged with PEDV. Further studies indicated that EA treatment significantly increased the proportion of white blood cells in blood and concentrations of IL-6, IL-1β, and IL-10 in the serum, but decreased the TNF-α content and gene expression of IL-6, IL-1β, TNF-α, and CXCL2 in the jejunum. Moreover, EA intervention considerably elevated the activity of total superoxide dismutase (T-SOD), but decreased the H2O2 concentration in the ileum of piglets. Importantly, EA suppressed the increased expression of antiviral-related genes and proteins (including MXI, ISG15, HSP70, and p-IRF7) induced by PEDV challenge in the jejunum. Furthermore, PEDV infection increased the protein abundance of p-JAK2 and p-STAT3, which were further enhanced by EA supplementation. In conclusion, our results revealed that EA could promote the restoration of intestinal homeostasis by regulating the interferon pathway that was interrelated with the activation of JAK2/STAT3 signaling. These findings provide theoretical basis for the use of EA as a therapy targeting PEDV infection in piglets.

Aquaporins: Potential Targets in Inflammatory Diseases

Inflammation involves a long chain of molecular reactions and cellular activity designed to repair tissue damaged by various causes. The inflammatory process and its complex mechanisms have recently become a focus of interest for many researchers. After the onset of inflammation, various adverse conditions that initiate the inflammatory response need to be addressed; however, failure to limit the inflammatory reaction may result in the damage or destruction of host cells. Therefore, inflammatory reactions play a role in many diferent diseases. Aquaporins (AQPs), commonly referred to as water channels, are protein channels responsible for forming pores in the membranes of biological cells. Their main function is to aid in the movement of water between cells. Aquaporins not only regulate transepithelial fluid transport across membranes but also play a role in regulating essential events crucial for the inflammatory response. Aquaporins have been shown in many studies to have important roles in inflammatory diseases. This clearly indicates that AQPs may be potential targets for inflammatory diseases. This review summarizes the research to date on the structure and function of AQPs and provides an update on the relationship between AQPs and various human inflammatory diseases.

Intestinal polyphenol antioxidant activity involves redox signaling mechanisms facilitated by aquaporin activity

Ascertaining whether dietary polyphenols evoke an antioxidant or prooxidant activity, which translates to a functional role required to maintain intestinal cell homeostasis continues to be an active and controversial area of research for food chemists and biochemists alike. We have proposed that the paradoxical function of polyphenols to autoxidize to generate H2O2 is a required first step in the capacity of some plant phenolics to function as intracellular antioxidants. This is based on the fact that cell redox homeostasis is achieved by a balance between H2O2 formation and subsequent outcomes of antioxidant systems function. Maintaining optimal extracellular and intracellular H2O2 concentrations is required for cell survival, since low levels are important to upregulate endogenous antioxidant capacity; whereas, concentrations that go beyond homeostatic control typically result in an inflammatory response, growth arrest, or eventual cell death. Aquaporins (AQPs) are a family of water channel membrane proteins that facilitate cellular transportation of water and other small molecule-derived solutes, such as H2O2, in all organisms. In the intestine, AQPs act as gatekeepers to regulate intracellular uptake of H2O2, generated from extracellular polyphenol autoxidation, thus enabling an intracellular cell signaling responses to mitigate onset of oxidative stress and intestinal inflammation. In this review, we highlight the potential role of AQPs to control important underlying mechanisms that define downstream regulation of intestinal redox homeostasis, specifically. It has been established that polyphenols that undergo oxidation to the quinone form, resulting in subsequent adduction to a thiol group on Keap1-Nrf2 complex, trigger Nrf2 activation and a cascade of indirect intracellular antioxidant effects. Here, we propose a similar mechanism that involves H2O2 generated from specific dietary polyphenols with a predisposition to undergo autoxidation. The ultimate bioactivity is regulated and expressed by AQP membrane function and thus, by extension, represents expression of an intracellular antioxidant chemoprotection mechanism.

Roles and regulation of Aquaporin-3 in maintaining the gut health: an updated review

Aquaporin-3 (AQP3) is a predominant water channel protein expressed in the intestine, and plays important roles in the gut physiology and pathophysiology due to its permeability to water, glycerol and hydrogen peroxide. In this review, we systematically summarized the current understanding of the expression of AQP3 in the intestine of different species, and focused on the potential roles of AQP3 in water transport, different types of diarrhea and constipation, intestinal inflammation, intestinal barrier function, oxidative stress, and autophagy. These updated findings have supported that AQP3 may function as an important target in maintaining gut health of human and animals.

Hetong decoction relieves loperamide-induced constipation in rats by regulating expression of aquaporins

OBJECTIVE

To investigate whether Hetong decoction (, HTT) alleviates constipation via regulating AQPs expression.

METHODS

Constipation in rats was induced by loperamide, and rats were randomly assigned into model (saline), HHT-low (95 g/kg), HTT-medium (190 g/kg), HTT-high (380 g/kg) and positive control (mosapride) groups. Then the defecation function, the concentration of serum arginine vasopressin (AVP) and cyclic adenosine monophosphate (cAMP), and the expression of AQP3 and AQP8 in colon tissues were assessed. NCM460 colon cells with AQP3 and AQP8 knockdown or overexpression were exposed to serum from rats that received low or high dose of HTT, followed by detection of AQP3 and AQP8 expression.

RESULTS

The model group showed lower fecal weight and water content, weaker intestinal transit, higher serum concentration of AVP and cAMP, increased proximal and distal AQP8 expression, increased proximal but decreased distal AQP3 expression. However, these trends were reversed in both the HTT group (low, medium and high dose) and the positive control group. In NCM460 cells, HTT dose-dependently stabilized AQP3 and AQP8 expression under AQP3/8 plasmid interference or overexpression.

CONCLUSIONS

HTT relieves constipation in rats through regulating AQP3 and AQP8 expression.

Dysbiosis of intestinal homeostasis contribute to Whitmania pigra edema disease

Whitmania pigra is widely used in traditional Chinese medicine. However, W. pigra is being threatened by an edema disease with unknown causes (WPE). In this study, a comprehensive exploration of virome, microbiome, and metabolome aberrations in the intestine of W. pigra was performed to address the aetiology of WPE. Virome analysis indicated that eukaryotic viruses did not contribute to WPE, whereas an expansion of Caudovirales was observed in WPE. Compared to the control, the microbial richness and diversity in diseased W. pigra decreased remarkably. Nine genera, including Aeromonas, Anaerotruncus, Vibrio, Proteocatella, Acinetobacter, and Brachyspira were overrepresented in WPE, whereas eleven genera, including Bifidobacterium, Phascolarctobacterium, Lactobacillus, Bacillus and AF12, were enriched in healthy individuals. Furthermore, certain metabolites, especially amino acids, short-chain fatty acids, and bile acids, were found to be linked to intestinal microbiota alterations in WPE. An integration of the microbiome and metabolome in WPE found that dysbiosis of the gut microbiota or metabolites caused WPE. Notably, W. pigra accepted intestinal microbiota transplantation from WPE donors developed WPE clinical signs eventually, and the dysbiotic intestinal microbiota can be recharacterized in this recipient W. pigra. Strikingly, pathological features of metanephridium and uraemic toxin enrichment in the gut indicated a putative interconnection between the gut and metanephridium in WPE, which represents the prototype of the gut-kidney axis in mammals. These finding exemplify the conservation of "microecological Koch's postulates" from annelids to insects and other vertebrates, which provides a direction of prevention and treatment for WPE and opens a new insight into the pathogenesis of aquatic animal diseases from an ecological perspective.

Insights into the Function of Aquaporins in Gastrointestinal Fluid Absorption and Secretion in Health and Disease

Aquaporins (AQPs), transmembrane proteins permeable to water, are involved in gastrointestinal secretion. The secretory products of the glands are delivered either to some organ cavities for exocrine glands or to the bloodstream for endocrine glands. The main secretory glands being part of the gastrointestinal system are salivary glands, gastric glands, duodenal Brunner's gland, liver, bile ducts, gallbladder, intestinal goblet cells, exocrine and endocrine pancreas. Due to their expression in gastrointestinal exocrine and endocrine glands, AQPs fulfill important roles in the secretion of various fluids involved in food handling. This review summarizes the contribution of AQPs in physiological and pathophysiological stages related to gastrointestinal secretion.

Integrated multiomics analysis reveals changes in liver physiological function in Aqp9 gene knockout mice

Aquaporin 9 (AQP9) is the main channel by which blood glycerol enters the liver, where it plays key roles in osmotic pressure regulation and energy metabolism. Previous studies have shown that AQP9 is involved in the pathogenesis of many liver diseases. In this study, we aimed to clarify the role of AQP9 in maintaining the physiological environment of the liver using Aqp9^-/- mice. We constructed Aqp9 knockout mice and used comprehensive multiomics analysis to elucidate the potential molecular effects of AQP9 expression on liver tissue. Knockout of Aqp9 reduced mouse body weight by affecting glycerol metabolism and led to hepatocyte death and inflammatory cell infiltration, which was confirmed by transcriptomics, proteomics and metabolomics. Moreover, knockout of Aqp9 triggered immune and inflammatory responses, leading to scattered and mild liver cell pyroptosis and compensatory liver cell proliferation.

Integrative analysis reveals marker genes for intestinal mucosa barrier repairing in clinical patients

This study aims to identify biomarkers of intestinal repair and provide potential therapeutic clues for improving functional recovery and prognostic performance after intestinal inflammation or injury. Here, we conducted a large-scale screening of multiple transcriptomic and scRNA-seq datasets of patients with inflammatory bowel disease (IBD), and identified 10 marker genes that potentially contribute to intestinal barrier repairing: AQP8, SULT1A1, HSD17B2, PADI2, SLC26A2, SELENBP1, FAM162A, TNNC2, ACADS, and TST. Analysis of a published scRNA-seq dataset revealed that expression of these healing markers were specific to absorptive cell types in intestinal epithelium. Furthermore, we conducted a clinical study where 11 patients underwent ileum resection demonstrating that upregulation of post-operative AQP8 and SULT1A1 expression were associated with improved recovery of bowel functions after surgery-induced intestinal injury, making them confident biomarkers of intestinal healing as well as potential prognostic markers and therapeutic targets for patients with impaired intestinal barrier functions.

Arctiin alleviates functional constipation by enhancing intestinal motility in mice

Functional constipation (FC), a common symptom that is primarily associated with intestinal motility dysfunction, is a common problem worldwide. Arctiin (Arc) is a lignan glycoside isolated from the Chinese herbal medicine Arctium lappa L., which is a health food in China. The present study aimed to evaluate the laxative effects of Arc against FC in mice. A model of FC induced by loperamide (5 mg/kg) was established in male Institute of Cancer Research (ICR) mice. Arc was administered at a dose of 100 mg/kg as a protective agent. The faecal status, intestinal motility and histological analyses were evaluated. Furthermore, the levels of gastrointestinal motility-associated neurotransmitters, such as motilin (MTL), nitric oxide (NO), and brain-derived neurotrophic factor (BDNF) and the protective effect of Arc on interstitial cells of Cajal (ICC) were assessed. Arc treatment reversed the loperamide-induced reduction in faecal number and water content and the intestinal transit ratio in ICR mice. Histological analysis confirmed that Arc administration mitigated colonic injury. Moreover, Arc treatment increased levels of motilin and brain-derived neurotrophic factor while decreasing nitric oxide levels and ICC injury in the colon of FC mice. Arc decreased inflammation induction and aquaporin expression levels. Owing to its pro-intestinal motility property, Arc was shown to have a protective effect against FC and may thus serve as a promising therapeutic strategy for the management of FC.

Supplemental enzymes and probiotics on the gut health of broilers fed with a newly harvested corn diet

Gut health is important for digestion and absorption of nutrient for animals. The purpose of this study was to investigate the therapeutic effect of enzymes and probiotics alone or in combination on the gut health of broilers fed with newly harvested corn diets. A total of 624 Arbor Acres Plus male broiler chickens were randomly divided into 8 treatment groups (PC: normal corn diet, NC: newly harvested corn diet, DE: NC + glucoamylase, PT: NC + protease, XL: NC + xylanase, BCC: NC + Pediococcus acidilactici BCC-1, DE + PT: NC + glucoamylase + protease, XL+BCC: NC + xylanase + Pediococcus acidilactici BCC-1). Each group was divided into 6 replicates, with 13 birds each. On d 21, intestinal morphological, intestinal tight junction and aquaporins gene expression, cecal short-chain fatty acid concentrations, and microflora were measured. Compared with the newly harvested corn diets (NC), supplemental glucoamylase (DE) significantly increased the relative abundance of Lachnospiraceae (P < 0.05) and decreased the relative abundance of Moraxellaceae (P < 0.05). Supplemental protease (PT) significantly increased the relative abundance of Barnesiella (P < 0.05), but the relative abundance of Campylobacter decreased by 44.4%. Supplemental xylanase (XL) significantly increased the jejunal mRNA expressions of MUC2, Claudin-1, and Occludin (P < 0.01), as well as the cecal digesta contents of acetic acid, butyric acid, and valeric acid (P < 0.01). Supplemental DE combined with PT increased the ileal mRNA expressions of aquaporins (AQP) 2, AQP5, and AQP7 (P < 0.01). Supplemental BCC significantly increased the jejunal villus height and crypt depth (P < 0.01), the jejunal mRNA expressions of MUC2, Claudin-1 and Occludin (P < 0.01), and the relative abundance of Bacteroides (P < 0.05). Supplemental xylanase in combination with BCC significantly increased jejunal villus height and crypt depth (P < 0.01), the ileal mRNA expressions of AQP2, AQP5 and AQP7 (P < 0.01), and the cecal digesta contents of acetic acid, butyric acid, and valeric acid (P < 0.01). This suggests that inclusions of supplemental protease (12,000 U/kg), glucoamylase (60,000 U/kg), or Pediococcus acidilactici BCC-1 (10⁹ cfu/kg) individually or in combination with xylanase (4,800 U/kg) in the newly harvested corn diets can alleviate diarrhea in broilers, and be beneficial for the gut health.

miR-152-3p facilitates cell adhesion and hepatic metastases in colorectal cancer via targeting AQP11

BACKGROUND

Tumor metastasis is a fundamental reason for the poor prognosis of colorectal cancer (CRC) patients. Publications suggested that upregulated Aquaporin-11 (AQP11) can improve CRC patients' prognoses, but few articles investigated the regulation of AQP11 in CRC cell adhesion and hepatic metastases. Therefore, this study will explore the regulatory mechanism of AQP11 regulating CRC cell adhesion and hepatic metastases at the molecular level.

METHODS

AQP11 and miR-152-3p expression were analyzed based on The Cancer Genome Atlas-Colon Adenocarcinoma/Rectum Adenocarcinoma (TCGA-COAD/READ) dataset and several other datasets. The upstream genes of AQP11 were predicted via StarBase and MicroRNA Data Integration Portal (mirDIP) databases. The signaling pathways in which the downregulated AQP11 enriched were analyzed via Gene Set Enrichment Analysis (GSEA). Cell proliferation, migration, invasion, and adhesion were respectively tested via western blot, Transwell, and cell adhesion assays. The expression of adhesion-related proteins was determined via enzyme-linked immunosorbent assay (ELISA). AQP11 protein level was examined via western blot, and AQP11 functions were validated via nude mice xenograft experiment.

RESULTS

AQP11 was downregulated in CRC, and the upregulated AQP11 remarkably repressed cell proliferation, migration, invasion, and adhesion. The silenced AQP11 notably facilitated the above cell functions in CRC. In addition, AQP11 was negatively regulated by miR-152-3p. In vitro cellular assays revealed that miR-152-3p, by targeting AQP11, facilitated CRC cell proliferation, migration, invasion, and adhesion. An in vivo assay suggested that AQP11 could notably repress CRC growth and metastasis.

CONCLUSION

The above results confirmed that miR-152-3p/AQP11 axis could regulate CRC hepatic metastases and would be a promising target in anti-cancer treatment.

Bifidobacterium bifidum CCFM1163 Alleviated Cathartic Colon by Regulating the Intestinal Barrier and Restoring Enteric Nerves

Cathartic colon (CC), a type of slow-transit constipation caused by the long-term use of stimulant laxatives, does not have a precise and effective treatment. This study aimed to evaluate the ability of Bifidobacterium bifidum CCFM1163 to relieve CC and to investigate its underlying mechanism. Male C57BL/6J mice were treated with senna extract for 8 weeks, followed by a 2-week treatment with B. bifidum CCFM1163. The results revealed that B. bifidum CCFM1163 effectively alleviated CC symptoms. The possible mechanism of B. bifidum CCFM1163 in relieving CC was analyzed by measuring the intestinal barrier and enteric nervous system (ENS)-related indices and establishing a correlation between each index and gut microbiota. The results indicated that B. bifidum CCFM1163 changed the gut microbiota by significantly increasing the relative abundance of Bifidobacterium, Faecalibaculum, Romboutsia, and Turicibacter as well as the content of short-chain fatty acids, especially propionic acid, in the feces. This increased the expression of tight junction proteins and aquaporin 8, decreased intestinal transit time, increased fecal water content, and relieved CC. In addition, B. bifidum CCFM1163 also increased the relative abundance of Faecalibaculum in feces and the expression of enteric nerve marker proteins to repair the ENS, promote intestinal motility, and relieve constipation.

AQP1 in the Gastrointestinal Tract of Mice: Expression Pattern and Impact of AQP1 Knockout on Colonic Function

Aquaporin 1 (AQP1) is one of thirteen known mammalian aquaporins. Its main function is the transport of water across cell membranes. Lately, a role of AQP has been attributed to other physiological and pathological functions including cell migration and peripheral pain perception. AQP1 has been found in several parts of the enteric nervous system, e.g., in the rat ileum and in the ovine duodenum. Its function in the intestine appears to be multifaceted and is still not completely understood. The aim of the study was to analyze the distribution and localization of AQP1 in the entire intestinal tract of mice. AQP1 expression was correlated with the hypoxic expression profile of the various intestinal segments, intestinal wall thickness and edema, as well as other aspects of colon function including the ability of mice to concentrate stools and their microbiome composition. AQP1 was found in a specific pattern in the serosa, the mucosa, and the enteric nervous system throughout the gastrointestinal tract. The highest amount of AQP1 in the gastrointestinal tract was found in the small intestine. AQP1 expression correlated with the expression profiles of hypoxia-dependent proteins such as HIF-1α and PGK1. Loss of AQP1 through knockout of AQP1 in these mice led to a reduced amount of bacteroidetes and firmicutes but an increased amount of the rest of the phyla, especially deferribacteres, proteobacteria, and verrucomicrobia. Although AQP-KO mice retained gastrointestinal function, distinct changes regarding the anatomy of the intestinal wall including intestinal wall thickness and edema were observed. Loss of AQP1 might interfere with the ability of the mice to concentrate their stool and it is associated with a significantly different composition of the of the bacterial stool microbiome.

Aquaporins in Glandular Secretion

Exocrine and endocrine glands deliver their secretory product, respectively, at the surface of the target organs or within the bloodstream. The release of their products has been shown to rely on secretory mechanisms often involving aquaporins (AQPs). This chapter will provide insight into the role of AQPs in secretory glands located within the gastrointestinal tract, including salivary glands, gastric glands, duodenal Brunner's glands, liver, gallbladder, intestinal goblets cells, and pancreas, as well and in other parts of the body, including airway submucosal glands, lacrimal glands, mammary glands, and eccrine sweat glands. The involvement of AQPs in both physiological and pathophysiological conditions will also be highlighted.

Non-Transport Functions of Aquaporins

Although it has been more than 20 years since the first aquaporin was discovered, the specific functions of many aquaporins are still under investigation, because various mice lacking aquaporins have no significant phenotypes. And in many studies, the function of aquaporin is not directly related to its transport function. Therefore, this chapter will focus on some unexpected functions of aquaporins, such the decreased tumor angiogenesis in AQP1 knockout mice, and AQP1 promotes cell migration, possibly by accelerating the water transport in lamellipodia of migrating cells. AQP transports glycerol, and water regulates glycerol content in epidermis and fat, thereby regulating skin hydration/biosynthesis and fat metabolism. AQPs may also be involved in neural signal transduction, cell volume regulation, and organelle physiology. AQP1, AQP3, and AQP5 are also involved in cell proliferation. In addition, AQPs have also been reported to play roles in inflammation in various tissues and organs. The functions of these AQPs may not depend on the permeability of small molecules such as water and glycerol, suggesting AQPs may play more roles in different biological processes in the body.

Aquaporins in Digestive System

In this chapter, we mainly discuss the expression and function of aquaporins (AQPs) expressed in digestive system. AQPs are highly conserved transmembrane protein responsible for water transport across cell membranes. AQPs in gastrointestinal tract include four members of aquaporin subfamily: AQP1, AQP4, AQP5, and AQP8, and three members of aquaglyceroporin subfamily: AQP3, AQP7, and AQP10. In the digestive glands, especially the liver, we discuss four members of aquaporin subfamily: AQP1, AQP4, AQP5, and AQP8, three members of aquaglyceroporin subfamily: AQP7, AQP9, and AQP12. In digestive system, the abnormal expression of AQPs is closely related to the occurrence and development of a variety of diseases. AQP1 is involved in saliva secretion and fat digestion and is closely related to gastric cancer and chronic liver disease; AQP3 is involved in the diarrhea and inflammatory bowel disease; AQP4 regulates gastric acid secretion and is associated with the development of gastric cancer; AQP5 is relevant to gastric carcinoma cell proliferation and migration; AQP7 is the major aquaglyceroporin in pancreatic β cells; AQP8 plays a role in pancreatic juice secretion and may be a potential target for the treatment of diarrhea; AQP9 plays considerable role in glycerol metabolism and hepatocellular carcinoma; Studies on the function of AQP10 and AQP12 are still limited. Further studies are necessary for specific locations and functions of AQPs in digestive system.

Daidzein Protects Caco-2 Cells against Lipopolysaccharide-Induced Intestinal Epithelial Barrier Injury by Suppressing PI3K/AKT and P38 Pathways

The intestinal epithelium provides an important barrier against bacterial endotoxin translocation, which can regulate the absorption of water and ions. The disruption of epithelial barrier function can result in water transport and tight junction damage, or further cause diarrhea. Therefore, reducing intestinal epithelial barrier injury plays an important role in diarrhea. Inflammatory response is an important cause of intestinal barrier defects. Daidzein improving the barrier integrity has been reported, but the effect on tight junction proteins and aquaporins is not well-described yet, and the underlying mechanism remains indistinct in the human intestinal epithelium. This study aimed to investigate the effects and mechanisms of daidzein on intestinal epithelial barrier injury induced by LPS, and a barrier injury model induced by LPS was established with human colorectal epithelial adenocarcinoma cell line Caco-2 cells. We found that daidzein protected the integrity of Caco-2 cell monolayers, reversed LPS-induced downregulation of ZO-1, occludin, claudin-1, and AQP3 expression, maintained intercellular junction of ZO-1, and suppressed NF-κB and the expression of inflammatory factors (TNF-α, IL-6). Furthermore, we found that daidzein suppressed the phosphorylation of the PI3K/AKT and P38 pathway-related proteins and the level of the related genes, and the PI3K/AKT and P38 pathway inhibitors increased ZO-1, occludin, claudin-1, and AQP3 expression. The study showed that daidzein could resist LPS-induced intestinal epithelial barrier injury, and the mechanism is related to suppressing the PI3K/AKT and P38 pathways. Therefore, daidzein could be a candidate as a dietary supplementation or drug to prevent or cure diarrhea.

Potential molecular mechanism of Guiqi Baizhu Decoction in radiation-induced intestinal edema by regulating HIF-1a, AQP4 and Na+/K+-ATPase

BACKGROUND

Guiqi Baizhu Decoction (GQBZD) has a good protective effect on radiation-induced intestinal edema (RIIE). However, the underlying molecular mechanisms need further elucidation.

PURPOSE

To reveal the potential mechanism of RIIE and GQBZD treatment.

METHODS

SD rats were irradiated with 6Gy X-ray to establish RIIE model. The general condition of the rats was observed; the dry/wet weight ratio of colon tissue was detected; the morphological changes of colon tissue were observed by HE staining; the expressions of ROS, HIF-1α and AQP4 in colon tissue were detected by confocal laser scanning; the expression of edema-related proteins was detected by Western blot. In addition, human colon epithelial cells (NCM460) was irradiated with 2Gy X-ray, and HIF-1α expression in NCM460 was knocked down by small interfering RNA (siRNA) transfection, and the activity of Na⁺/K⁺-ATPase was detected by enzyme activity kit; the ROS expression was detected by flow cytometer; the AQP4 expression was detected by laser confocal microscopy; and the expression of edema-related proteins were detected by Western blot.

RESULTS

We found that after irradiation, the colon tissue of rats was significantly edema, mainly manifested as mucosal and submucosal edema, and the ultrastructure was reflected in the structural damage of nucleus and mitochondria. ROS, HIF-1α and AQP4 were significantly expressed, and Na⁺/K⁺-ATPase expression/activity was decreased. After the intervention of GQBZD, the edema of the colon tissue of the rats was improved, the expressions of ROS, HIF-1α and AQP4 were decreased, and the expression/activity of Na⁺/K⁺-ATPase was increased.

CONCLUSION

Ionizing radiation (IR) can cause significant intestinal edema. AQP4 and Na⁺/K⁺-ATPase are the key factors of RIIE, which are regulated by ROS and HIF-1α. GQBZD can improve hypoxia and oxidative stress, regulate the expression of AQP4 and Na⁺/K⁺-ATPase, and achieve a protective effect on RIIE. This study is the first to reveal the mechanism of RIIE.

Aquaporins: A new target for traditional Chinese medicine in the treatment of digestive system diseases

Aquaporins (AQPs) are a family of transmembrane proteins expressed in various organ systems. Many studies have shown that the abnormal expression of AQPs is associated with gastrointestinal, skin, liver, kidneys, edema, cancer, and other diseases. The majority of AQPs are expressed in the digestive system and have important implications for the physiopathology of the gastrointestinal tract as well as other tissues and organs. AQP regulators can prevent and treat most gastrointestinal-related diseases, such as colorectal cancer, gastric ulcer, and gastric cancer. Although recent studies have proposed clinically relevant AQP-targeted therapies, such as the development of AQP inhibitors, clinical trials are still lacking and there are many difficulties. Traditional Chinese medicine (TCM) has been used in China for thousands of years to prevent, treat and diagnose diseases, and is under the guidance of Chinese medicine (CM) theory. Herein, we review the latest research on the regulation of AQPs by TCMs and their active components, including Rhei Radix et Rhizoma, Atractylodis macrocephalae Rhizoma, Salviae miltiorrhizae Radix et Rhizoma, Poria, Astragali radix, and another 26 TCMs, as well as active components, which include the active components include anthraquinones, saponins, polysaccharides, and flavonoid glycosides. Through our review and discussion of numerous studies, we attempt to explore the regulatory effects of TCMs and their active components on AQP expression in the corresponding parts of the body in terms of the Triple Energizer concept in Chinese medicine defined as "upper energizer, middle energizer, and lower energizer,"so as to offer unique opportunities for the development of AQP-related therapeutic drugs for digestive system diseases.

Mucosa-interfacing electronics

The surface mucosa that lines many of our organs houses myriad biometric signals and, therefore, has great potential as a sensor-tissue interface for high-fidelity and long-term biosensing. However, progress is still nascent for mucosa-interfacing electronics owing to challenges with establishing robust sensor-tissue interfaces; device localization, retention and removal; and power and data transfer. This is in sharp contrast to the rapidly advancing field of skin-interfacing electronics, which are replacing traditional hospital visits with minimally invasive, real-time, continuous and untethered biosensing. This Review aims to bridge the gap between skin-interfacing electronics and mucosa-interfacing electronics systems through a comparison of the properties and functions of the skin and internal mucosal surfaces. The major physiological signals accessible through mucosa-lined organs are surveyed and design considerations for the next generation of mucosa-interfacing electronics are outlined based on state-of-the-art developments in bio-integrated electronics. With this Review, we aim to inspire hardware solutions that can serve as a foundation for developing personalized biosensing from the mucosa, a relatively uncharted field with great scientific and clinical potential.

Clinical value and molecular mechanism of AQGPs in different tumors

Aquaglyceroporins (AQGPs), including AQP3, AQP7, AQP9, and AQP10, are transmembrane channels that allow small solutes across biological membranes, such as water, glycerol, H₂O₂, and so on. Increasing evidence suggests that they play critical roles in cancer. Overexpression or knockdown of AQGPs can promote or inhibit cancer cell proliferation, migration, invasion, apoptosis, epithelial-mesenchymal transition and metastasis, and the expression levels of AQGPs are closely linked to the prognosis of cancer patients. Here, we provide a comprehensive and detailed review to discuss the expression patterns of AQGPs in different cancers as well as the relationship between the expression patterns and prognosis. Then, we elaborate the relevance between AQGPs and malignant behaviors in cancer as well as the latent upstream regulators and downstream targets or signaling pathways of AQGPs. Finally, we summarize the potential clinical value in cancer treatment. This review will provide us with new ideas and thoughts for subsequent cancer therapy specifically targeting AQGPs.

Aquaporin 8ab is required in zebrafish embryonic intestine development

The aquaporin 8 (AQP8) is a small integral membrane protein that selectively transports water and other small uncharged solutes across cell plasma membranes. It has been demonstrated that AQP8 is ubiquitously present in various tissues and organs of mammals, and participates in many physiological and pathological processes. Recent studies showed that AQP8 is highly expressed in the columnar epithelial cells of mammalian colonic mucosa facing lumen, indicating that AQP8 plays potential roles in the physiology and pathophysiology of gastrointestinal tract. However, the role of AQP8 during gastrointestinal tract development is unclear. In the present study, RT-PCR results reveal that the zebrafish genome encodes three kinds of aqp8s ( aqp8aa, aqp8ab, and aqp8b). We use whole mount in situ hybridization to describe aqp8 genes spatiotemporal expression pattern, and the results show that aqp8ab mRNA is detectable mainly in the zebrafish embryonic intestine. To reveal the details of aqp8ab distribution, histological sections are employed. Transverse sections indicate that aqp8ab mRNA expression is more intense in the layer lining the intestinal cavity. Knockout of aqp8ab using the CRISPR/Cas9 system induces intestine development defects and abnormal formation of intestinal lumen. In addition, aqp8ab mRNA significantly rescues the intestine defects in the aqp8ab mutant. These results indicate that aqp8ab is required in the intestine development of zebrafish.

Bifidobacterium animalis subsp. lactis XLTG11 improves antibiotic-related diarrhea by alleviating inflammation, enhancing intestinal barrier function and regulating intestinal flora

Antibiotic-associated diarrhea (AAD) is a common side effect during antibiotic treatment. In this study, we evaluated the regulatory effect of Bifidobacterium animalis subsp. lactis XLTG11 on mouse diarrhea caused by antibiotic-induced intestinal flora disturbance. Then, two strains of Bifidobacterium animalis subsp. lactis XLTG11 and Bifidobacterium animalis subsp. lactis BB-12 were administered to AAD mice. We found that the recovery effect of using B. lactis XLTG11 was better than that of B. lactis BB-12. B. lactis XLTG11 reduced the pathological characteristics of the intestinal tract, and significantly reduced the levels of lipopolysaccharide (LPS), D-lactic acid (D-LA) and diamine oxidase (DAO) to decrease intestinal permeability. In addition, these two strains significantly increased the expression of aquaporin and tight junction proteins, and inhibited toll-like receptor 4 (TLR4)/activation of the nuclear factor-κB (NF-κB) signaling pathway, significantly increased the levels of anti-inflammatory cytokines and decreased levels of pro-inflammatory cytokines. Moreover, after treatment with B. lactis XLTG11, the contents of acetic acid, propionic acid, butyric acid and total short-chain fatty acids were significantly increased. Compared with the MC group, B. lactis XLTG11 increased the abundance and diversity of the intestinal flora and changed the composition of the intestinal flora. We found that B. lactis XLTG11 can promote the recovery of intestinal flora and mucosal barrier function, thereby effectively improving AAD-related symptoms, providing a scientific basis for future clinical applications.

Expression alteration and dysfunction of ion channels/transporters in the parietal cells induces gastric diffused mucosal injury

Gastric mucosal injuries include focal and diffused injuries, which do and do not change the cell differentiation pattern. Parietal cells loss is related to the occurrence of gastric mucosal diffused injury, with two phenotypes of spasmolytic polypeptide-expressing metaplasia and neuroendocrine cell hyperplasia, which is the basis of gastric cancer and gastric neuroendocrine tumor respectively. Multiple ion channels and transporters are located and expressed in the parietal cells, which is not only regulate the gastric acid-base homeostasis, but also regulate the growth and development of parietal cells. Therefore, alteration and dysregulation of ion channels and transporters in the parietal cells impairs the morphology and physiological functions of stomach, resulted in gastric diffused mucosal damage. In this review, multiple ion channels and transporters in parietal cells, including K+ channels, aquaporins, Cl- channels, Na+/H+ transporters, and Cl-/HCO3- transporters are described, and their roles in gastric diffused mucosal injury are discussed. We hope to drive researcher's attention to focus on the role of ion channels/transporters loss in the parietal cells induced gastric diffused mucosal injury.

A Proximal-to-Distal Survey of Healthy Adult Human Small Intestine and Colon Epithelium by Single-Cell Transcriptomics

BACKGROUND & AIMS

Single-cell transcriptomics offer unprecedented resolution of tissue function at the cellular level, yet studies analyzing healthy adult human small intestine and colon are sparse. Here, we present single-cell transcriptomics covering the duodenum, jejunum, ileum, and ascending, transverse, and descending colon from 3 human beings.

METHODS

A total of 12,590 single epithelial cells from 3 independently processed organ donors were evaluated for organ-specific lineage biomarkers, differentially regulated genes, receptors, and drug targets. Analyses focused on intrinsic cell properties and their capacity for response to extrinsic signals along the gut axis across different human beings.

RESULTS

Cells were assigned to 25 epithelial lineage clusters. Multiple accepted intestinal stem cell markers do not specifically mark all human intestinal stem cells. Lysozyme expression is not unique to human Paneth cells, and Paneth cells lack expression of expected niche factors. Bestrophin 4 (BEST4)⁺ cells express Neuropeptide Y (NPY) and show maturational differences between the small intestine and colon. Tuft cells possess a broad ability to interact with the innate and adaptive immune systems through previously unreported receptors. Some classes of mucins, hormones, cell junctions, and nutrient absorption genes show unappreciated regional expression differences across lineages. The differential expression of receptors and drug targets across lineages show biological variation and the potential for variegated responses.

CONCLUSIONS

Our study identifies novel lineage marker genes, covers regional differences, shows important differences between mouse and human gut epithelium, and reveals insight into how the epithelium responds to the environment and drugs. This comprehensive cell atlas of the healthy adult human intestinal epithelium resolves likely functional differences across anatomic regions along the gastrointestinal tract and advances our understanding of human intestinal physiology.

Signaling Mechanisms and Pharmacological Modulators Governing Diverse Aquaporin Functions in Human Health and Disease

The aquaporins (AQPs) are a family of small integral membrane proteins that facilitate the bidirectional transport of water across biological membranes in response to osmotic pressure gradients as well as enable the transmembrane diffusion of small neutral solutes (such as urea, glycerol, and hydrogen peroxide) and ions. AQPs are expressed throughout the human body. Here, we review their key roles in fluid homeostasis, glandular secretions, signal transduction and sensation, barrier function, immunity and inflammation, cell migration, and angiogenesis. Evidence from a wide variety of studies now supports a view of the functions of AQPs being much more complex than simply mediating the passive flow of water across biological membranes. The discovery and development of small-molecule AQP inhibitors for research use and therapeutic development will lead to new insights into the basic biology of and novel treatments for the wide range of AQP-associated disorders.

Effects of a Chinese herbal extract on the intestinal tract and aquaporin in Adriamycin-induced nephropathy

Wuling Decoction is a traditional Chinese medicine that has been used to open knots, benefit water, transform Qi, return fluid, and has a significant effect on strengthening the spleen and removing dampness. To explore the effects of Wuling Decoction on the intestinal tract and aquaporin in Adriamycin-induced nephropathy, 45 specific pathogen free (SPF) Wistar rats were randomly divided into a blank control group (5 rats), Dosing control group (10 rats), Adriamycin nephropathy model group (10 rats), diarrhea group (10 rats), and an Adriamycin nephropathy diarrhea model group (10 rats). The tissue localization of aquaporin (AQP) was determined by immunohistochemistry. The expression of AQP mRNA and protein was measured by RT-PCR and western blot analysis, respectively. The results indicated that Wuling Decoction causes excretion of AQP2 through the urine, regulates AQP2 levels, and exerts diuretic and anti-diarrheal effects. It also regulates the levels of antidiuretic hormone (ADH) and arginine vasopressin (AVP), affects water absorption rate, and reduces the level of cyclic adenosine monophosphate (cAMP) in each tissue, thus reducing the absorption of AQP2 to water. Wuling Decoction promoted AQP2 expression in the nephropathy model group and inhibited AQP2 expression in the diarrhea group. Wuling Decoction increased the expression of aquaporin in the intestinal tract, reduced the water content of stool by promoting the absorption of water in the intestinal tract, inhibited the expression of aquaporin and its regulatory factors in nephridia tissue, and reduced the reabsorption of water to increase urine volume, to decrease the occurrence of diarrhea.

Extracts of Poria cocos improve functional dyspepsia via regulating brain-gut peptides, immunity and repairing of gastrointestinal mucosa

BACKGROUND

Poria cocos (Schw.) Wolf (PC), a fungus, has been used for more than 2000 years as a food and medicine in China. It has a very good therapeutic effect for functional dyspepsia (FD). However, the material basis and mechanism of PC on FD were not reported.

PURPOSE

To investigate the function and potential mechanisms of PC including its three extracts (triterpenoid, PCT; water-soluble polysaccharide, PCWP; acidic polysaccharide, PCAP) on FD.

STUDY DESIGN

The study explored the therapeutic effect of PC and its three extracts on FD in rats for the first time and discussed its mechanisms based on brain-gut peptides, immunity and repair of the gastrointestinal mucosa.

METHODS

The chemical components of PC extracts were analyzed and quantified using ultra high performance liquid chromatography coupled with quadrupole time of flight mass spectrometry (UPLC-Q-TOF-MS) and gel permeation chromatography coupled with size exclusion chromatography (GPC/SEC). The FD rat models were established using weight-loaded forced swimming and alternate-day fasting for 42 days. After 14 days of treatment, the effect and mechanisms were investigated using ELISA, histopathology, immunohistochemistry as well as Western blot.

RESULTS

Seventy-seven triterpenoids in PCT were identified. PCWP was primarily composed of component A (Mw: 3.831 × 10⁷ Da), component B (Mw: 5.650 × 10⁶ Da) and component C (Mw: 113,117 Da). PCAP was a homogeneous composition with an average Mw of 74,320 Da. PCT, PCWP and PCAP alleviated the symptoms of FD. These extracts promoted the repair of gastrointestinal mucosa and regulated the balance between the T helper cell (Th)1/Th2 axis and the Th17/Treg axis. PCT and PCWP regulated brain-gut peptides more effectively, PCWP and PCAP enhanced immunity more effectively. Further study demonstrated that these extracts may have enhanced immunity via the Toll-like receptor (TLR) and c-Jun N-terminal kinase (JNK) signaling pathways.

CONCLUSIONS

PC extracts showed therapeutic effects on FD rats, and the mechanism of action involved multiple pathways. PCAP, which is often discarded in traditional applications, was effective. Our study provides new ideas for the application and development of PC extracts.

Boric acid transport activity of human aquaporins expressed in Xenopus oocytes

Boric acid is a vital micronutrient that is toxic at high concentrations in animals. However, the mechanisms underlying boric acid transport in animal cells remain unclear. To identify the plasma membrane boric acid channels in animals, we analyzed the function of human aquaporins (AQPs), which are homologous to the nodulin-like intrinsic protein family of plant boric acid channels. When human AQPs were expressed in Xenopus laevis oocytes, the results of the swelling assay showed that boric acid permeability significantly increased in oocytes expressing AQP3, 7, 8, 9, and 10, but not in those expressing AQP1, 2, 4, and 5. The boric acid influxes of these oocytes were also confirmed by elemental quantification. Electrophysiological analysis using a pH microelectrode showed that these AQPs transported boric acid (B(OH)3 ) but not borate ions (B(OH)4- ). These results indicate that AQP3, 7, 8, 9, and 10 act as boric acid transport systems, likely as channels in humans.

Overexpression of an aquaporin protein from Aspergillus glaucus confers salt tolerance in transgenic soybean

Salt stress is an important abiotic factor that causes severe losses in soybean yield and quality. Therefore, breeding salt-tolerant soybean germplasm resources via genetic engineering has gained importance. Aspergillus glaucus, a halophilic fungus that exhibits significant tolerance to salt, carries the gene AgGlpF. In this study, we used the soybean cotyledonary node transformation method to transfer the AgGlpF gene into the genome of the soybean variety Williams 82 to generate salt-tolerant transgenic soybean varieties. The results of PCR, Southern blot, ddPCR, and RT-PCR indicated that AgGlpF was successfully integrated into the soybean genome and stably expressed. When subjected to salt stress conditions via treatment with 250 mM NaCl for 3 d, the transgenic soybean plants showed significant tolerance compared with wild-type plants, which exhibited withering symptoms and leaf abscission after 9 d. The results of this study indicated that the transfer of AgGlpF into the genome of soybean plants produced transgenic soybean with significantly improved salt stress tolerance.

Pathophysiological role of ion channels and transporters in gastrointestinal mucosal diseases

The incidence of gastrointestinal (GI) mucosal diseases, including various types of gastritis, ulcers, inflammatory bowel disease and GI cancer, is increasing. Therefore, it is necessary to identify new therapeutic targets. Ion channels/transporters are located on cell membranes, and tight junctions (TJs) affect acid-base balance, the mucus layer, permeability, the microbiota and mucosal blood flow, which are essential for maintaining GI mucosal integrity. As ion channel/transporter dysfunction results in various GI mucosal diseases, this review focuses on understanding the contribution of ion channels/transporters to protecting the GI mucosal barrier and the relationship between GI mucosal disease and ion channels/transporters, including Cl-/HCO3- exchangers, Cl- channels, aquaporins, Na+/H+ exchangers, and K+ channels. Here, we provide novel prospects for the treatment of GI mucosal diseases.

Pharmacology, Toxicology, and Metabolism of Sennoside A, A Medicinal Plant-Derived Natural Compound

Sennoside A (SA) is a natural dianthrone glycoside mainly from medicinal plants of Senna and Rhubarb, and used as a folk traditional irritant laxative and slimming health food. Accumulating evidences suggest that SA possesses numerous pharmacological properties, such as laxative, anti-obesity, hypoglycemic, hepatoprotective, anti-fibrotic, anti-inflammatory, anti-tumor, anti-bacterial, anti-fungal, anti-viral, and anti-neurodegenerative activities. These pharmacological effects lay the foundation for its potential application in treating a variety of diseases. However, numerous published studies suggest that a long-term use of SA in large doses may have some adverse effects, including the occurrence of melanosis coli and carcinogenesis of colon cancer, thereby limiting its clinical use. It remains to be established whether SA or its metabolites are responsible for the pharmacological and toxicity effects. In this review, the latest advances in the pharmacology, toxicology, and metabolism of SA were summarizedbased on its biological characteristics and mechanism.