Three cheers for the goblet cell: maintaining homeostasis in mucosal epithelia

Integrative network pharmacology and multi-omics to study the potential mechanism of Niuhuang Shangqing Pill on acute pharyngitis

ETHNOPHARMACOLOGICAL RELEVANCE

Niuhuang Shangqing Pill (NSP) is a renowned Chinese medicine prescription listed in the Chinese Pharmacopoeia (Edition, 2020; volume 1) and is utilized in clinical practice for treating headaches and acute pharyngitis (AP) associated with "Shanghuo". Despite its widespread use, the pharmacological mechanism and bioactive components underlying NSP in treating AP remain unclear.

AIM OF THE STUDY

This study delved into evaluate the alleviation effect of NSP on AP and explore the mechanisms by analyzing multi-omics.

MATERIALS AND METHODS

UHPLC-Q Exactive Orbitrap HRMS was employed for the chemical ingredients of NSP. Multiple compositions, targets and pathways involved in the treatment of AP with NSP were predicted by network pharmacology. Additionally, wistar rat model of AP induced by capsaicin was established to evaluate the anti-AP activity of NSP in vivo. The potential mechanism of NSP to improve AP was investigated by real-time PCR, pharyngeal transcriptome analysis, non-targeted metabolomics, immunofluorescence and Western blot.

RESULTS

119 compounds were identified by UHPLC-Q Exactive Orbitrap HRMS. Both clinical data of Gene Expression Omnibus (GEO) and network pharmacology demonstrated that MAPK signaling pathway and TNF signaling pathway were the critical pathway for AP treatment. In rat model of AP induced by capsaicin, NSP demonstrated the ability to reduce the levels of IL-1β, TNF-α, IL-6, CGRP, SP, PGE2, COX-2 in serum. Moreover, Transcriptomics analysis comprehensively indicated that NSP regulated the MAPK signaling pathway, TNF signaling pathway, biosynthesis of phenylalanine, tyrosine and tryptophan, arachidonic acid metabolism in AP rats. Metabolomics analysis verified that NSP could rebalance arachidonic acid metabolism, biosynthesis of phenylalanine, tyrosine and tryptophan and regulate metabolic profiles. Multi-omics Correlation analysis exhibited that the relative expression of Tnfrsf1b was significantly negatively correlated with 12(S)-HPETE. Immunofluorescence, real-time PCR and Western blot of pharyngeal tissue revealed that NSP inhibited the TNF/p38-MAPK/NF-κB signaling pathway. Additionally, in vitro study on RAW264.7 cells confirmed that NSP counteract LPS-induced inflammatory by inhibiting the TNF/p38-MAPK/NF-κB signaling pathway. Overall, NSP effectively ameliorated capsaicin-induced AP by modulating the arachidonic acid metabolism and TNF/p38-MAPK/NF-κB signaling pathway.

CONCLUSION

NSP effectively ameliorated capsaicin-induced AP by modulating the arachidonic acid metabolism, biosynthesis of phenylalanine, tyrosine and tryptophan, as well as the TNF/p38-MAPK/NF-κB signaling pathway.

Pulmonary-delivered Anticalin Jagged-1 antagonists reduce experimental airway mucus hyperproduction and obstruction

Mucus hypersecretion and mucus obstruction are pathogenic features in many chronic lung diseases directly linked to disease severity, exacerbation, progression, and mortality. The Jagged-1/Notch pathway is a promising therapeutic target that regulates secretory and ciliated cell trans-differentiation in the lung. However, the Notch pathway is also required in various other organs. Hence, pulmonary delivery of therapeutic agents is a promising approach to target this pathway while minimizing systemic exposure. Using Anticalin technology, Jagged-1 Anticalin binding proteins were generated and engineered to potent and selective inhalable Jagged-1 antagonists. Their therapeutic potential to reduce airway mucus hyperproduction and obstruction was investigated ex vivo and in vivo. In primary airway cell cultures grown at an air-liquid interface and stimulated with inflammatory cytokines, Jagged-1 Anticalin binding proteins reduced both mucin gene expression and mucous cell metaplasia. In vivo, prophylactic and therapeutic treatment with a pulmonary-delivered Jagged-1 Anticalin binding protein reduced mucous cell metaplasia, epithelial thickening, and airway mucus hyperproduction in IL-13 and house dust mite allergen-challenged mice, respectively. Furthermore, in a transgenic mouse model with pathophysiologic features of cystic fibrosis and chronic obstructive pulmonary disease (COPD), pulmonary-delivered Jagged-1 Anticalin binding protein reduced hallmarks of airway mucus obstruction. In all in vivo models, a reduction of mucous cells with a concomitant increase of ciliated cells was observed. Collectively, these findings support Jagged-1 antagonists' therapeutic potential for patients with muco-obstructive lung diseases and the feasibility of targeting the Jagged-1/Notch pathway by inhalation.NEW & NOTEWORTHY Airway mucus drives severity and mortality in diverse chronic lung diseases. The Jagged-1/Notch pathway controls the balance of ciliated versus mucous cells, but targeting the pathway systemically carries the risk of side effects. Here we developed novel, Anticalin-derived, pulmonary-delivered Jagged-1 antagonists, to inhibit airway mucus hyperproduction and obstruction in chronic lung diseases. Our preclinical data demonstrate the effectiveness of these antagonists in diminishing secretory cell and mucus levels and alleviating hallmarks of mucus obstruction.

Investigating tributyltin's toxic effects: Intestinal barrier and neuroenteric disruption in rat's jejunum

The expansion of economic activities in coastal areas has significantly increased chemical contamination, leading to major environmental challenges. Contaminants enter the human body through the food chain, particularly via seafood and water consumption, triggering biomagnification and bioaccumulation processes. The gastrointestinal tract (GIT) acts as a selective barrier, protecting against chemical pollutants and maintaining homeostasis through a complex network of cells and immune responses. This study assessed impact of tributyltin (TBT), a highly toxic organometallic compound used in antifouling coatings for ships, on the GIT and myenteric neural plasticity in young rats. TBT exposure leads to histopathological changes, including epithelial detachment and inflammatory foci, especially at lower environmental doses. The study found that TBT causes significant reductions in villi height, increases in goblet cells and intraepithelial lymphocytes, and disrupts the myenteric plexus, with higher densities of extraganglionic neurons in exposed animals.

Modified Zhenwu Decoction improved intestinal barrier function of experimental colitis through activation of sGC-mediated cGMP/PKG signaling

BACKGROUND

The invasion of luminal antigens and an aberrant immune response resulting from a disrupted physical epithelial barrier are the key characteristics of ulcerative colitis (UC). The restoration of damaged epithelial function is crucial for maintaining mucosal homeostasis and disease quiescence. Current therapies for UC primarily focus on suppressing inflammation. However, most patients fail to respond to therapy or develop secondary resistance over time, emphasizing the need to develop novel therapeutic targets for UC. Our study aimed to identify the potential targets of a novel modified herbal formula from the Zhen Wu Decoction, namely CDD-2103, which has demonstrated promising efficacy in treating chronic colitis.

METHODS

The effect of CDD-2103 on epithelial barrier function was examined using in vitro and ex vivo models of tissue injury, as well as a chronic colitis C57BL/6 mouse model. Transcriptomic analysis was employed to profile gene expression changes in colonic tissues following treatment with CDD-2103.

RESULTS

Our in vivo experiments demonstrated that CDD-2103 dose-dependently reduced disease severity in mice with chronic colitis. The efficacy of CDD-2103 was mediated by a reduction in goblet cell loss and the enhancement of tight junction protein integrity. Mechanistically, CDD-2103 suppressed epithelial cell apoptosis and tight junction protein breakdown by activating the soluble guanynyl cyclase (sGC)-mediated cyclic guanosine monophosphate (cGMP)/PKG signaling cascade. Molecular docking analysis revealed strong sGC ligand recognition by the CDD-2103-derived molecules, warranting further investigation.

CONCLUSION

Our study revealed a novel formulation CDD-2103 that restores intestinal barrier function through the activation of sGC-regulated cGMP/PKG signaling. Furthermore, our findings suggest that targeting sGC can be an effective approach for promoting mucosal healing in the management of UC.

Vitamin B5 supplementation enhances intestinal development and alters microbes in weaned piglets

This study explored the effects of different vitamin B5 (VB5) levels on intestinal growth and function of weaned piglets. Twenty-one piglets (7.20 ± 1.11 kg) were included in a 28-day feeding trial with three treatments, including 0 mg/kg (L-VB5), 10 mg/kg (Control) and 50 mg/kg (H-VB5) of VB5 supplement. The results showed that: Large intestine weight/body weight was the highest in H-VB5 group, Control and H-VB5 groups had significantly higher villus height and villus height/crypt depth than the L-VB5 in the ileum (p < .05). Goblet cells (ileal crypt) and endocrine cells (ileal villus) significantly increased in Control and H-VB5 (p < .05). The H-VB5 group exhibited significantly higher levels of ki67 and crypt depth in the cecum and colon, colonic goblet cells and endocrine cells were both rising considerably (p < .05). Isobutyric acid and isovaleric acid were significantly reduced in the H-VB5 group (p < .05), and there was a decreasing trend in butyric acid (p = .073). At the genus level, the relative abundance of harmful bacteria such as Clostridium_Sensu_Structo_1 Strecto_1, Terrisporbacter and Streptococcus decreased significantly and the relative abundance of beneficial bacteria Turicibacter increased significantly in H-VB5 group (p < .05). Overall, the addition of 50 mg/kg VB5 primarily enhanced the morphological structure, cell proliferation and differentiation of the ileum, cecum and colon. It also had a significant impact on the gut microbiota and short-chain fatty acids.

Simple Epithelial Transplantation for Ocular Surface Reconstruction After Severe Ocular Burn Injury

PURPOSE

To manage ocular surface complications and recover conjunctival and corneal epithelia after unilateral severe chemical burn.

METHODS

We performed simple conjunctival epithelial transplantation (SCET) to obtain renewal of fornix and bulbar-tarsal conjunctiva epithelium, followed by simple limbal epithelial transplantation (SLET) to recover limbal function and epithelial corneal surface. Slit-lamp examination, fluorescein staining, in vivo confocal microscopy, Kheirkhah grading system for symblepharon severity, Wong-Baker FACES Pain Rating Scale, and best-corrected visual acuity were assessed before surgery, at 1 to 3 months after SCET and SLET, and thereafter at 6 to 12 to 36 months.

RESULTS

Two patients with unilateral burn injuries underwent surgery. Eye mobility and fornix reconstruction were promptly achieved, and conjunctival epithelium with goblet cells was observed on the bulbar and tarsal conjunctiva 3 months after SCET. After SLET, corneal epithelium and cornea-conjunctiva transition zone were observed at 3 and 6 months, respectively. From before surgery to 6 months after SLET, symblepharon improved from grade IVa2 and IIIb2 to Ic0 and Ib0, the Wong-Baker FACES Pain Rating Scale changed from grade 6 and 4 to 0, and best-corrected visual acuity upgraded from 1.40 and 1.10 logarithm of the minimum angle of resolution to 0.5 logarithm of the minimum angle of resolution, in patient 1 and 2, respectively. After 3 years, results remained stable.

CONCLUSIONS

SCET effectively healed the bare conjunctival area relieving subjective symptoms and discomfort. Sequential SCET and SLET showed to be feasible in restoring a normal ocular surface with long-lasting results suggesting the aim in patients with severe ocular burn is not merely corneal epithelium renewal but also the regeneration of ocular surface homeostasis.

ADORA3 activation promotes goblet cell differentiation via enhancing HMGCS2-mediated ketogenesis in ulcerative colitis

ADORA3 is mainly expressed in intestinal tract, and has the potential to promote the expression of mucin 2 (MUC2), the function-related factor of goblet cells, under asthma conditions. This study aims to confirm the induction and mechanisms of ADORA3 activation on goblet cells in ulcerative colitis (UC). A significant decrease in ADORA3 expression was found in mucosal biopsies from UC patients and in the colons of colitis mice. This reduction correlated negatively with disease severity and positively with goblet cell number. ADORA3 activation mitigated dextran sulfate sodium (DSS)-induced colitis and facilitated ATOH1-mediated goblet cell differentiation in both in vivo and in vitro. Metabolomics analysis unveiled that ADORA3 activation bolstered ketogenesis, leading to elevated levels of the metabolite BHB. Subsequently, BHB heightened the activity of HDAC1/2, augmenting histone acetylation at the H3K9ac site within the promoter region of the ATOH1 gene. Furthermore, the reason for ADORA3 activation to enhance ketogenesis was attributed to controlling the competitive binding among β-arrestin2, SHP1 and PPARγ. This results in the non-ligand-dependent activation of PPARγ, thereby promoting the transcription of HMGCS2. The exact mechanisms by which ADORA3 promoted goblet cell differentiation and alleviated UC were elucidated using MRS1191 and shHMGCS2 plasmid. Collectively, ADORA3 activation promoted goblet cell differentiation and alleviated UC by enhancing ketogenesis via the "BHB-HDAC1/2-H3K9ac" pathway.

Cyclic adenosine 3', 5'-monophosphate (cAMP) signaling is a crucial therapeutic target for ulcerative colitis

The pathogenesis of ulcerative colitis (UC), a chronic intestine inflammatory disease primarily affecting adolescents, remains uncertain. Contemporary studies suggest that a confluence of elements, including genetic predispositions, environmental catalysts, dysregulated immune responses, and disturbances in the gut microbiome, are instrumental in the initiation and advancement of UC. Among them, inflammatory activation and mucosal barrier damage caused by abnormal immune regulation are essential links in the development of UC. The impairment of the mucosal barrier is intricately linked to the interplay of various cellular mechanisms, including oxidative stress, autophagy, and programmed cell death. An extensive corpus of research has elucidated that level of cyclic adenosine 3',5'-monophosphate (cAMP) undergo modifications in the midst of inflammation and participate in a diverse array of cellular operations that mitigate inflammation and the impairment of the mucosal barrier. Consequently, a plethora of pharmacological agents are currently under development, with some advancing through clinical trials, and are anticipated to garner approval as novel therapeutics. In summary, cAMP exerts a crucial influence on the onset and progression of UC, with fluctuations in its activity being intimately associated with the severity of the disease's manifestation. Significantly, this review unveils the paramount role of cAMP in the advancement of UC, offering a tactical approach for the clinical management of individuals afflicted with UC.

Glucose-Stimulated Mucus Secretion by Goblet Cells Mitigates Intestinal Barrier Dysfunction in a Rat Model of Mesenteric Ischemia/Reperfusion Injury

Background

Superior mesenteric ischemia/reperfusion (I/R) causes barrier dysfunction and facilitates bacterial translocation (BT) in the small intestine, which can even lead to systemic sepsis. Our previous research showed that luminal administration of glucose and its anaerobic glycolytic metabolites exerted cytoprotective effects on epithelial cells and ameliorated I/R-induced BT in the liver and spleen. Notably, the reduction of BT occurs over the whole intestinal tract, not only restricted in the ligated glucose-containing loop.

Objectives

In this study, we hypothesized that local jejunal glucose-contacting might confer on the remote intestinal epithelium regeneration potential, fortify their barrier function and goblet cell secretory activity.

Methods

Two 10-cm jejunal segments were isolated in Wistar rats. One segment was ligatured at both ends and infused with Krebs buffer containing 0- or 50-mM glucose (local loop), whereas the adjacent segment was left unaltered and not exposed to glucose (remote loop). The rats then underwent either a sham operation or I/R challenge by occlusion of the superior mesenteric artery for 20 min, followed by reperfusion for 1 h.

Results

Enteral addition of glucose in the local jejunum loop alleviated ischemia-induced barrier defects, histopathological scores, cell death, and mucosal inflammation (myeloperoxidase and inflammatory cytokine production) in the remote jejunum. After ischemia, goblet cells in the remote jejunum showed cavitation of mucin granules and low MUC2 expression. Local addition of glucose enhanced MUC2 synthesis and stimulated a jet-like mucus secretion in the remote jejunum, which was accompanied by the restoration of crypt activity.

Conclusions

Our results showed local enteral glucose effectively mitigates I/R-induced barrier dysfunction, suggesting that local glucose-stimulated mucus secretion by remote goblet cells may serve to mitigate mucosal inflammation and BT. We provide a more precise barrier protection role of enteral glucose upon I/R challenge, presenting new opportunities for future therapeutic potential.

Protopine-Type Alkaloids Alleviate Lipopolysaccharide-Induced Intestinal Inflammation and Modulate the Gut Microbiota in Mice

In this study, we assessed the therapeutic effects of Macleaya cordata (Willd). R. Br.-derived protopine-type alkaloids (MPTAs) in a mouse model of lipopolysaccharide (LPS)-induced intestinal inflammation. The experimental design involved the allocation of mice into distinct groups, including a control group, a model group treated with 6 mg/kg LPS, a berberine group treated with 50 mg/kg berberine hydrochloride and low-, medium- and high-dose MPTA groups treated with 6, 12 and 24 mg/kg MPTAs, respectively. Histological analysis of the ileum, jejunum and duodenum was performed using Hematoxylin and Eosin (H&E) staining. Moreover, the quantification of intestinal goblet cells (GCs) was performed based on PAS staining. The serum levels of IL-1β, IL-6, IL-8 and TNF-α were quantified using an enzyme-linked immunosorbent assay (ELISA), while the mRNA levels of TLR4, NF-κB p65, NLRP3, IL-6 and IL-1β were assessed using quantitative PCR (qPCR). The protein levels of TLR4, Md-2, MyD88, NF-κB p65 and NLRP3 were determined using Western blotting. Furthermore, the 16S rDNA sequences of bacterial taxa were amplified and analysed to determine alterations in the gut microbiota of the mice following MPTA treatment. Different doses of MPTAs were found to elicit distinct therapeutic effects, leading to enhanced intestinal morphology and an increased abundance of intestinal GCs. A significant decrease was noted in the levels of pro-inflammatory cytokines (IL-1β, IL-6, IL-8 and TNF-α). Additionally, the protein levels of TLR4, MyD88, NLRP3 and p-p65/p65 were markedly reduced by MPTA treatment. Furthermore, 16S rDNA sequencing analysis revealed that the administration of 24 mg/kg MPTAs facilitated the restoration of microbial composition.

Effect of acetylcholinesterase inhibition on immune cells in the murine intestinal mucosa

The gastrointestinal tract (GI) is the largest immune organ whose function is controlled by a complex network of neurons from the enteric nervous system (ENS) as well as the sympathetic and parasympathetic system. Evolving evidence indicates that cross-communication between gut-innervating neurons and immune cells regulates many essential physiological functions including protection against mucosal infections. We previously demonstrated that following paraoxon treatment, 70 % of the mice were able to survive an oral infection with S. typhimurium, a virulent strain of Salmonella enterica serovar Typhimurium. The present study aims to investigate the effect that rivastigmine, a reversible AChE inhibitor used for the treatment of neurodegenerative diseases, has on the murine immune defenses of the intestinal mucosa. Our findings show that, similar to what is observed with paraoxon, administration of rivastigmine promoted the release of secretory granules from goblet and Paneth cells, resulting in increased mucin layer. Surprisingly, however, and unlike paraoxon, rivastigmine treatment did not affect overall mortality of infected mice. In order to investigate the mechanistic basis for the differential effects observed between paraoxon and rivastigmine, we used multi-color flowcytometric analysis to characterize the immune cell landscape in the intraepithelial (IE) and lamina propria (LP) compartments of intestinal mucosa. Our data indicate that treatment with paraoxon, but not rivastigmine, led to an increase of resident CD3+CD8+ T lymphocytes in the ileal mucosa (epithelium and lamina propria) and CD11b- CD11c+ dendritic cells in the LP. Our findings indicate the requirement for persistent cholinergic pathway engagement to effect a change in the cellular landscape of the mucosal tissue that is necessary for protection against lethal bacterial infections. Moreover, optimal protection requires a collaboration between innate and adaptive mucosal immune responses in the intestine.

Mechanism insights into the histopathological changes of polypropylene microplastics induced gut and liver in zebrafish

Microplastics (MPs), emerging as significant pollutants, have been consistently detected in aquatic environments, with the Yangtze River experiencing a particularly severe level of microplastic pollution, exceeding all other watersheds in China. Polypropylene (PP), the plastic most abundantly found in the middle and lower reaches of the Yangtze River Basin, has less comprehensive research results into its toxic effects. Consequently, the present investigation employed zebrafish as a model organism to delve into the toxicological impacts of polypropylene microplastics (PP-MPs) with a diameter of 5 μm across varying concentrations (300 mg/L and 600 mg/L). Using histopathological, microbiota profiling, and transcriptomic approaches, we systematically evaluated the impact of PP-MPs exposure on the intestine and liver of zebrafish. Histopathological analysis revealed that exposure to PP-MPs resulted in thinner intestinal walls, damaged intestinal mucosa, and hepatic cellular damage. Intestinal microbiota profiling demonstrated that, the richness, uniformity, diversity, and homogeneity of gut microbes significantly increased after the PP-MPs exposure at high concentration. These alterations were accompanied by shifts in the relative abundance of microbiota associated with intestinal pathologies, suggesting a profound impact on the intestinal microbial community structure. Concurrently, hepatic transcriptome analysis and RT-qPCR indicated that the downregulation of pathways and genes associated with cell proliferation regulation and DNA damage repair mechanisms contributed to hepatic cellular damage, ultimately exerting adverse effects on the liver. Correlation analysis between the intestinal microbiota and liver transcriptome profiles further highlighted significant associations between intestinal microbiota and the downregulated hepatic pathways. Collectively, these results provide novel insights into the subacute toxicological mechanisms of PP-MPs in aquatic organisms and highlight the need for further research on the ecological and health risks associated with PP-MPs pollution.

Disease-specific transcriptional programs govern airway goblet cell metaplasia

Hypersecretion of airway mucus caused by goblet cell metaplasia is a characteristic of chronic pulmonary inflammatory diseases including asthma, cystic fibrosis (CF), and chronic obstructive pulmonary disease (COPD). Goblet cells originate from airway progenitor club cells. However, the molecular mechanisms and features of goblet cell metaplasia in lung disease are poorly understood. Herein, public single-cell RNA sequencing datasets of human lungs were reanalyzed to explore the transitional phase as club cells differentiate into goblet cells in asthma, CF, and COPD. We found that changes in club and goblet cells during pathogenesis and cellular transition were associated with signalling pathways related to immune response, oxidative stress, and apoptosis. Moreover, other key drivers of goblet cell specification appeared to be pathologically specific, with interleukin (IL)-13 and hypoxia inducible factor 1 (HIF-1)-induced genetic changes in asthma, cystic fibrosis transmembrane conductance regulator (CFTR) mutation being present in CF, and interactions with CD8+ T cells, mitophagy, and mitochondria-induced apoptosis in COPD. In conclusion, this study revealed the similarities and differences in goblet cell metaplasia in asthma, CF, and COPD at the transcriptome level, thereby providing insights into possible novel therapeutic approaches for these diseases.

PIM1-HDAC2 axis modulates intestinal homeostasis through epigenetic modification

The mucosal barrier is crucial for intestinal homeostasis, and goblet cells are essential for maintaining the mucosal barrier integrity. The proviral integration site for Moloney murine leukemia virus-1 (PIM1) kinase regulates multiple cellular functions, but its role in intestinal homeostasis during colitis is unknown. Here, we demonstrate that PIM1 is prominently elevated in the colonic epithelia of both ulcerative colitis patients and murine models, in the presence of intestinal microbiota. Epithelial PIM1 leads to decreased goblet cells, thus impairing resistance to colitis and colitis-associated colorectal cancer (CAC) in mice. Mechanistically, PIM1 modulates goblet cell differentiation through the Wnt and Notch signaling pathways. Interestingly, PIM1 interacts with histone deacetylase 2 (HDAC2) and downregulates its level via phosphorylation, thereby altering the epigenetic profiles of Wnt signaling pathway genes. Collectively, these findings investigate the unknown function of the PIM1-HDAC2 axis in goblet cell differentiation and ulcerative colitis/CAC pathogenesis, which points to the potential for PIM1-targeted therapies of ulcerative colitis and CAC.

Mucosal barrier status in Atlantic salmon fed rapeseed oil and Schizochytrium oil partly or fully replacing fish oil through winter depression

The study was designed to investigate the effects of replacing fish oil by algal oil and rapeseed oil on histomorphology indices of the intestine, skin and gill, mucosal barrier status and immune-related genes of mucin and antimicrobial peptide (AMP) genes in Atlantic salmon (Salmo salar). For these purposes, Atlantic salmon smolts were fed three different diets. The first was a control diet containing fish oil but no Schizochytrium oil. In the second diet, almost 50 % of the fish oil was replaced with algal oil, and in the third diet, fish oil was replaced entirely with algal oil. The algal oil contained mostly docosahexaenoic acid (DHA) and some eicosapentaenoic acid (EPA). The study lasted for 49 days in freshwater (FW), after which some fish from each diet group were transferred to seawater (SW) for a 48-h challenge test at 33 ppt to test their ability to tolerate high salinity. Samples of skin, gills, and mid intestine [both distal (DI) and anterior (AI) portions of the mid intestine] were collected after the feeding trial in FW and after the SW-challenge test to assess the effects of the diets on the structure and immune functions of the mucosal surfaces. The results showed that the 50 % VMO (Veramaris® algal oil) dietary group had improved intestinal, skin, and gill structures. Principal component analysis (PCA) of the histomorphological parameters demonstrated a significant effect of the algal oil on the intestine, skin, and gills. In particular, the mucosal barrier function of the intestine, skin, and gills was enhanced in the VMO 50 % dietary group after the SW challenge, as evidenced by increased mucous cell density. Immunolabelling of heat shock protein 70 (HSP70) in the intestine (both DI and AI) revealed downregulation of the protein expression in the 50 % VMO group and a corresponding upregulation in the 100 % VMO group compared to 0 % VMO. The reactivity of HSP70 in the epithelial cells was higher after the SW challenge compared to the FW phase. Immune-related genes related to mucosal defense, such as mucin genes [muc2, muc5ac1 (DI), muc5ac1 (AI), muc5ac2, muc5b (skin), and muc5ac1 (gills)], and antimicrobial peptide genes [def3 (DI), def3 (AI), and cath1 (skin)] were significantly upregulated in the 50 % VMO group. PCA of gene expression demonstrated the positive influences on gene regulation in the 50 % VMO dietary group. In conclusion, this study demonstrated the positive effect of substituting 50 % of fish oil with algal oil in the diets of Atlantic salmon. The findings of histomorphometry, mucosal mapping, immunohistochemistry, and immune-related genes connected to mucosal responses all support this conclusion.

Investigation the mechanism of iron overload-induced colonic inflammation following ferric citrate exposure

Iron overload occurs due to excessive iron intake compared to the body's demand, leading to iron deposition and impairment of multiple organ functions. Our previous study demonstrated that chronic oral administration of ferric citrate (FC) caused colonic inflammatory injury. However, the precise mechanism underlying this inflammatory response remains unclear. The current study aims to investigate the mechanism by which iron overload induced by FC exposure leads to colonic inflammation. To accomplish this, mice were orally exposed to three different concentrations of FC (71 mg/kg/bw (L), 143 mg/kg/bw (M) and 286 mg/kg/bw (H)) for continuous 16 weeks, with the control group receiving ultrapure water (C). Exposure to FC caused disturbances in the excretory system, altered colonic flora alpha diversity, and enriched pathogenic bacteria, such as Mucispirillum, Helicobacter, Desulfovibrio, and Shigella. These changes led to structural disorders of the colonic flora and an inflammatory response phenotype characterized by inflammatory cells infiltration, atrophy of intestinal glands, and irregular thickening of the intestinal wall. Mechanistic studies revealed that FC-exposure activated the NF-κB signaling pathway by up-regulating TLR4, MyD88, and NF-κB mRNA levels and protein expression. This activation resulted in increased production of pro-inflammatory cytokines, further contributing to the colonic inflammation. Additionally, in vitro experiments in SW480 cells confirmed the activation of NF-κB signaling pathway by FC exposure, consistent with the in vivo findings. The significance of this study lies in its elucidation of the mechanism by which iron overload caused by FC exposure leads to colonic inflammation. By identifying the role of pathogenic bacteria and the NF-κB signaling pathway, this study could potentially offer a crucial theoretical foundation for the research on iron overload, as well as provide valuable insights for clinical iron supplementation.

Nanomedicines for intranasal delivery: understanding the nano-bio interactions at the nasal mucus-mucosal barrier

INTRODUCTION

Intranasal administration is an effective drug delivery routes in modern pharmaceutics. However, unlike other in vivo biological barriers, the nasal mucosal barrier is characterized by high turnover and selective permeability, hindering the diffusion of both particulate drug delivery systems and drug molecules. The in vivo fate of administrated nanomedicines is often significantly affected by nano-biointeractions.

AREAS COVERED

The biological barriers that nanomedicines encounter when administered intranasally are introduced, with a discussion on the factors influencing the interaction between nanomedicines and the mucus layer/mucosal barriers. General design strategies for nanomedicines administered via the nasal route are further proposed. Furthermore, the most common methods to investigate the characteristics and the interactions of nanomedicines when in presence of the mucus layer/mucosal barrier are briefly summarized.

EXPERT OPINION

Detailed investigation of nanomedicine-mucus/mucosal interactions and exploration of their mechanisms provide solutions for designing better intranasal nanomedicines. Designing and applying nanomedicines with mucus interaction properties or non-mucosal interactions should be customized according to the therapeutic need, considering the target of the drug, i.e. brain, lung or nose. Then how to improve the precise targeting efficiency of nanomedicines becomes a difficult task for further research.

In vitro modelling of bacterial pneumonia: a comparative analysis of widely applied complex cell culture models

Bacterial pneumonia greatly contributes to the disease burden and mortality of lower respiratory tract infections among all age groups and risk profiles. Therefore, laboratory modelling of bacterial pneumonia remains important for elucidating the complex host-pathogen interactions and to determine drug efficacy and toxicity. In vitro cell culture enables for the creation of high-throughput, specific disease models in a tightly controlled environment. Advanced human cell culture models specifically, can bridge the research gap between the classical two-dimensional cell models and animal models. This review provides an overview of the current status of the development of complex cellular in vitro models to study bacterial pneumonia infections, with a focus on air-liquid interface models, spheroid, organoid, and lung-on-a-chip models. For the wide scale, comparative literature search, we selected six clinically highly relevant bacteria (Pseudomonas aeruginosa, Mycoplasma pneumoniae, Haemophilus influenzae, Mycobacterium tuberculosis, Streptococcus pneumoniae, and Staphylococcus aureus). We reviewed the cell lines that are commonly used, as well as trends and discrepancies in the methodology, ranging from cell infection parameters to assay read-outs. We also highlighted the importance of model validation and data transparency in guiding the research field towards more complex infection models.

Two-Photon and Multiphoton Microscopy in Anterior Segment Diseases of the Eye

Two-photon excitation microscopy (TPM) and multiphoton fluorescence microscopy (MPM) are advanced forms of intravital high-resolution functional microscopy techniques that allow for the imaging of dynamic molecular processes and resolve features of the biological tissues of interest. Due to the cornea's optical properties and the uniquely accessible position of the globe, it is possible to image cells and tissues longitudinally to investigate ocular surface physiology and disease. MPM can also be used for the in vitro investigation of biological processes and drug kinetics in ocular tissues. In corneal immunology, performed via the use of TPM, cells thought to be intraepithelial dendritic cells are found to resemble tissue-resident memory T cells, and reporter mice with labeled plasmacytoid dendritic cells are imaged to understand the protective antiviral defenses of the eye. In mice with limbal progenitor cells labeled by reporters, the kinetics and localization of corneal epithelial replenishment are evaluated to advance stem cell biology. In studies of the conjunctiva and sclera, the use of such imaging together with second harmonic generation allows for the delineation of matrix wound healing, especially following glaucoma surgery. In conclusion, these imaging models play a pivotal role in the progress of ocular surface science and translational research.

Bacteroides methylmalonyl-CoA mutase produces propionate that promotes intestinal goblet cell differentiation and homeostasis

Propionate is a short-chain fatty acid that is generated upon microbiome-mediated fiber fermentation in the intestine. By modulating immune and metabolic pathways, propionate exerts many health benefits. Key bacterial species, such as Bacteroides thetaiotaomicron, generate propionate, but the biochemical pathways and specific functions remain undetermined. We identified a gene operon-encoding methylmalonyl-CoA mutase (MCM) that contributes to propionate biosynthesis in B. thetaiotaomicron. Colonization of germ-free mice with wild-type or MCM-deficient strains as well as in vitro examination demonstrated that MCM-mediated propionate production promotes goblet cell differentiation and mucus-related gene expression. Intestinal organoids lacking the propionate receptor, GPR41, showed reduced goblet cell differentiation upon MCM-mediated propionate production. Furthermore, although wild-type B. thetaiotaomicron alleviated DSS-induced intestinal inflammation, this effect was abolished in mice receiving the MCM-deficient strain but restored upon propionate supplementation. These data emphasize the critical role of MCM-mediated propionate biosynthesis in goblet cell differentiation, offering potential pathways to ameliorate colitis.

The importance of the gut microbiome and its signals for a healthy nervous system and the multifaceted mechanisms of neuropsychiatric disorders

Increasing evidence links the gut microbiome and the nervous system in health and disease. This narrative review discusses current views on the interaction between the gut microbiota, the intestinal epithelium, and the brain, and provides an overview of the communication routes and signals of the bidirectional interactions between gut microbiota and the brain, including circulatory, immunological, neuroanatomical, and neuroendocrine pathways. Similarities and differences in healthy gut microbiota in humans and mice exist that are relevant for the translational gap between non-human model systems and patients. There is an increasing spectrum of metabolites and neurotransmitters that are released and/or modulated by the gut microbiota in both homeostatic and pathological conditions. Dysbiotic disruptions occur as consequences of critical illnesses such as cancer, cardiovascular and chronic kidney disease but also neurological, mental, and pain disorders, as well as ischemic and traumatic brain injury. Changes in the gut microbiota (dysbiosis) and a concomitant imbalance in the release of mediators may be cause or consequence of diseases of the central nervous system and are increasingly emerging as critical links to the disruption of healthy physiological function, alterations in nutrition intake, exposure to hypoxic conditions and others, observed in brain disorders. Despite the generally accepted importance of the gut microbiome, the bidirectional communication routes between brain and gut are not fully understood. Elucidating these routes and signaling pathways in more detail offers novel mechanistic insight into the pathophysiology and multifaceted aspects of brain disorders.

Intraperitoneal insufflation of carbon dioxide rescues intestinal damage in an experimental murine model of colitis

OBJECTIVES

Necrotizing enterocolitis (NEC) is a severe neonatal surgical condition, associated with a prolonged pro-inflammatory state, leading to high mortality and morbidity rates. Carbon dioxide (CO2 ) insufflation during laparoscopy may have an anti-inflammatory effect. We aimed to evaluate the effects of CO2 -insufflation on experimental colitis.

METHODS

Acute colitis was induced in 6-week-old Balb/c mice by the administration of 2%-dextran sulfate-sodium (DSS) during 7 days (n = 45). On Day 4, two groups received intraperitoneal insufflation (duration: 30 mn, pressure: 5 mmHg) of CO2 ("DSS+CO2 ") or air ("DSS+air"). A group received no insufflation ("DSS"). Groups were compared for clinical severity using the disease activity index (DAI-body weight loss, stool consistency, and bleeding), histological severity (histopathological activity index, colon length, and ulcerations), colonic mucosecretion, and inflammation.

RESULTS

DAI was significantly decreased in DSS+CO2 group, compared to DSS (p < 0.0001) or DSS+air (p < 0.0001) groups. Colon length was increased in DSS+CO2 treated mice compared to DSS (p = 0.0002). The histopathological activity index was lower in DSS+CO2 (vs. DSS, p = 0.0059/vs. DSS+air, p = 0.0389), with decreased ulcerations (3.77 vs. 10.7, p = 0.0306), and persistent mucosecretion with increased mucin-secreting cells.

CONCLUSIONS

CO2 -insufflation attenuates DSS-induced colitis and improves both clinical and histological scores. Laparoscopy with CO2 insufflation represents a therapeutic anti-inflammatory strategy for NEC.

Maximizing Treatment Options for IBD through Drug Repurposing

Chronic inflammation characterizes Inflammatory Bowel Disease (IBD), encompassing Crohn's Disease (CD) and Ulcerative Colitis (UC). Despite modest activity of disease in most UC patients, exacerbations occur, especially in those with severe symptoms, necessitating interventions, like colectomy. Current treatments for IBD, predominantly small molecule therapies, impose significant economic burdens. Drug repurposing offers a cost-effective alternative, leveraging existing drugs for novel therapeutic applications. This approach capitalizes on shared molecular pathways across diseases, accelerating therapeutic discovery while minimizing costs and risks. This article provides an overview of IBD and explores drug repurposing as a promising avenue for more effective and affordable treatments. Through computational and animal studies, potential drug candidates are categorized, offering insights into IBD pathogenesis and treatment strategies.

New insights into the unfolded protein response (UPR)-anterior gradient 2 (AGR2) pathway in the regulation of intestinal barrier function in weaned piglets

Sustained dysfunction of the intestinal barrier caused by early weaning is a major factor that induces postweaning diarrhea in weaned piglets. In both healthy and diseased states, the intestinal barrier is regulated by goblet cells. Alterations in the characteristics of goblet cells are linked to intestinal barrier dysfunction and inflammatory conditions during pathogenic infections. In this review, we summarize the current understanding of the mechanisms of the unfolded protein response (UPR) and anterior gradient 2 (AGR2) in maintaining intestinal barrier function and how modifications to these systems affect mucus barrier characteristics and goblet cell dysregulation. We highlight a novel mechanism underlying the UPR-AGR2 pathway, which affects goblet cell differentiation and maturation and the synthesis and secretion of mucin by regulating epidermal growth factor receptor and mucin 2. This study provides a theoretical basis and new insights into the regulation of intestinal health in weaned piglets.

Effects of Enterotoxigenic Escherichia coli Challenge on Jejunal Morphology and Microbial Community Profiles in Weaned Crossbred Piglets

Pathogenic enterotoxigenic Escherichia coli (ETEC) is a major cause of bacterial diarrhea in weaning piglets, which are vulnerable to changes in environment and feed. This study aimed to determine the effects of the ETEC challenge on piglet growth performance, diarrhea rate, jejunal microbial profile, jejunal morphology and goblet cell distribution. A total of 13 piglets from one litter were selected on postnatal day 21 and assigned to treatments with or without ETEC challenge at 1 × 108 CFUs, as ETEC group or control group, respectively. On postnatal day 28, samples were collected, followed by the detection of serum biochemical indexes and inflammatory indicators, HE staining, PAS staining and 16S rDNA gene amplicon sequencing. Results showed that the growth performance decreased, while the diarrhea rate increased for the ETEC group. The jejunum is the main segment of the injured intestine during the ETEC challenge. Compared with the control, the ETEC group displayed fewer goblet cells in the jejunum, where goblet cells are more distributed at the crypt and less distributed at the villus. In addition, ETEC piglets possessed higher abundances of the genus Desulfovibrio, genus Oxalobacter and genus Peptococus and lower abundances of the genus Prevotella 2, genus Flavonifractor and genus Blautra. In terms of alpha diversity, Chao 1 and observed features indexes were both increased for the ETEC group. Our study provides insights into jejunal histopathological impairment and microbial variation in response to ETEC infection for weaned piglets and is a valuable reference for researchers engaged in animal health research to select stress models.

Role of transforming growth factor-β in airway remodelling in bronchiolitis obliterans

Airway remodelling is the main pathological mechanism of bronchiolitis obliterans (BO). Several studies have found that transforming growth factor-β (TGF-β) expression is increased in BO during airway remodelling, where it plays an important role in various biological processes by binding to its receptor complex to activate multiple signalling proteins and pathways. This review examines the role of TGF-β in airway remodelling in BO and its potential as a therapeutic target, highlighting the mechanisms of TGF-β activation and signalling, cellular targets of TGF-β actions, and research progress in TGF-β signalling and TGF-β-mediated processes.

A cocktail of small molecules maintains the stemness and differentiation potential of conjunctival epithelial cells

PURPOSE

The conjunctival epithelial cells cultured with bovine serum or feeder cells were not suitable for clinical application. Therefore, we developed a novel serum-free and feeder cell-free culture system containing only a cocktail of three chemicals (3C) to expand the conjunctival epithelial cells.

METHODS

The cell proliferative ability was evaluated by counting, crystal violet staining and Ki67 immunostaining. Co-staining of K7 and MUC5AC was performed to identify goblet cells. PAS staining was used to assess the ability of cells to synthesis and secrete glycoproteins. In vivo, eye drops containing 3C was administered to verify the role of 3C in the mouse conjunctival injury model. PAS, HE and immunofluorescence staining were performed to show conjunctival epithelial repair.

RESULTS

Compared with other small molecule groups and the serum group, the cells in 3C group showed superior morphology and proliferative ability. Meanwhile, 3C maintained the well-proliferative capacity of cells even after fifth passage. The 3C group also exhibited more K7 and MUC5AC double positive cells, and the PAS staining positive areas were present in both the cytoplasm and extracellular matrix. The cell sheets treated with 3C in air-lifted culture were obviously stratified. In vivo, more goblet cells in the conjunctival epithelium were observed in the 3C group.

CONCLUSION

Overall, our culture system can expand the conjunctival epithelial cells and retain their potential to differentiate into mature goblet cells, which provided a promising source of seed cells for conjunctival reconstruction. Furthermore, this system provides new insights for the clinical treatment of ocular surface diseases.

Medication adjustment of afatinib and combination therapy with sitagliptin for alleviating afatinib-induced diarrhea in rats

Afatinib, as the first-line treatment for non-small cell lung cancer (NSCLC), causes severe gastrointestinal adverse reactions that greatly affect patients' quality of life and even potentially result in treatment discontinuation. Multiple dose adjustments and concomitant use of anti-diarrheal medications are commonly employed to manage diarrhea, also allowing for a recovery period between each adjustment. However, these approaches are based on empirical guidance and still have limitations. This study aims to explore reliable approaches to alleviate diarrhea by focusing on two strategies: adjusting the dosing regimen of afatinib itself and implementing combination therapy. In this study, we firstly revealed a dose-dependent relationship between afatinib-induced diarrhea and gastrointestinal epithelial damage, resulting in atrophy, reduced expression of tight junction proteins, and increased permeability. We further found that even after discontinuation of the medication, although the severity of diarrhea had improved to baseline, the tight junction proteins and permeability of the intestinal epithelium did not fully recover, and the pharmacokinetics studies showed that drug absorption significantly increased than normal. This indicated the recovery period was longer than expected and may accelerate the occurrence of subsequent episodes of diarrhea. Hence, it would be prudent to consider adjustments to the starting dose or the recovery interval. Furthermore, we initially investigated the relationship between DPP enzyme and afatinib-induced diarrhea and found a significant decrease in plasma DPP enzyme activity following afatinib-induced diarrhea. Subsequently, we conducted continuous treatment with sitagliptin and observed significant improvement in afatinib-induced diarrhea. We observed that sitagliptin can promote the production of anti-inflammatory factors, increase the expression of intestinal epithelial tight junction proteins, and improve intestinal microbiota, further validating the mechanism through the use of GLP-23-33 as GLP-2 receptor inhibitor. In conclusion, sitagliptin exhibits promising potential as a therapeutic option for managing afatinib-induced diarrhea. Taken together, our study provides valuable insights into alleviating afatinib-induced diarrhea through both afatinib medication adjustment and sitagliptin combination therapy.

Goblet cell-associated antigen passage: A gatekeeper of the intestinal immune system

Effective delivery of luminal antigens to the underlying immune system is the initial step in generating antigen-specific responses in the gut. However, a large body of information regarding the immune response activation process remains unknown. Recently, goblet cells (GCs) have been reported to form goblet cell-associated antigen passages (GAPs). Luminal antigens can be transported inside GAPs and reach subepithelial immune cells to induce antigen-specific immune responses, contributing largely to gut homeostasis and the prevention of some intestinal diseases like allergic enteritis and bacterial translocation. In this article, we summarized recent observations on the formation of intestinal GAPs and their roles in mucosal immunity. We hope that this review can offer a fresh perspective and valuable insights for clinicians and researchers interested in studying the intestinal immune system.

Specific Blood Plasma Circulating miRs Are Associated with the Physiological Impact of Total Fish Meal Replacement with Soybean Meal in Diets for Rainbow Trout (Oncorhynchus mykiss)

High dietary SBM content is known to induce important physiological alterations, hampering its use as a major FM alternative. Rainbow trout (Oncorhynchus mykiss) juveniles were fed two experimental diets during 9 weeks: (i) a FM diet containing 12% FM; and (ii) a vegetable meal (VM) diet totally devoid of FM and based on SBM (26%). Fish fed the VM diet did not show reduced growth performance when compared with fish fed the FM diet. Nevertheless, fish fed the VM diet had an increased viscerosomatic index, lower apparent fat digestibility, higher aminopeptidase enzyme activity and number of villi fusions, and lower α-amylase enzyme activity and brush border integrity. Small RNA-Seq analysis identified six miRs (omy-miR-730a-5p, omy-miR-135c-5p, omy-miR-93a-3p, omy-miR-152-5p, omy-miR-133a-5p, and omy-miR-196a-3p) with higher expression in blood plasma from fish fed the VM diet. Bioinformatic prediction of target mRNAs identified several overrepresented biological processes known to be associated with high dietary SBM content (e.g., lipid metabolism, epithelial integrity disruption, and bile acid status). The present research work increases our understanding of how SBM dietary content has a physiological impact in farmed fish and suggests circulating miRs might be suitable, integrative, and less invasive biomarkers in fish.

Porcine Deltacoronavirus Infection Disrupts the Intestinal Mucosal Barrier and Inhibits Intestinal Stem Cell Differentiation to Goblet Cells via the Notch Signaling Pathway

Goblet cells and their secreted mucus are important elements of the intestinal mucosal barrier, which allows host cells to resist invasion by intestinal pathogens. Porcine deltacoronavirus (PDCoV) is an emerging swine enteric virus that causes severe diarrhea in pigs and causes large economic losses to pork producers worldwide. To date, the molecular mechanisms by which PDCoV regulates the function and differentiation of goblet cells and disrupts the intestinal mucosal barrier remain to be determined. Here, we report that in newborn piglets, PDCoV infection disrupts the intestinal barrier: specifically, there is intestinal villus atrophy, crypt depth increases, and tight junctions are disrupted. There is also a significant reduction in the number of goblet cells and the expression of MUC-2. In vitro, using intestinal monolayer organoids, we found that PDCoV infection activates the Notch signaling pathway, resulting in upregulated expression of HES-1 and downregulated expression of ATOH-1 and thereby inhibiting the differentiation of intestinal stem cells into goblet cells. Our study shows that PDCoV infection activates the Notch signaling pathway to inhibit the differentiation of goblet cells and their mucus secretion, resulting in disruption of the intestinal mucosal barrier. IMPORTANCE The intestinal mucosal barrier, mainly secreted by the intestinal goblet cells, is a crucial first line of defense against pathogenic microorganisms. PDCoV regulates the function and differentiation of goblet cells, thereby disrupting the mucosal barrier; however, the mechanism by which PDCoV disrupts the barrier is not known. Here, we report that in vivo, PDCoV infection decreases villus length, increases crypt depth, and disrupts tight junctions. Moreover, PDCoV activates the Notch signaling pathway, inhibiting goblet cell differentiation and mucus secretion in vivo and in vitro. Thus, our results provide a novel insight into the mechanism underlying intestinal mucosal barrier dysfunction caused by coronavirus infection.

Study of the roles of caspase-3 and nuclear factor kappa B in myenteric neurons in a P2X7 receptor knockout mouse model of ulcerative colitis

BACKGROUND

The literature indicates that the enteric nervous system is affected in inflammatory bowel diseases (IBDs) and that the P2X7 receptor triggers neuronal death. However, the mechanism by which enteric neurons are lost in IBDs is unknown.

AIM

To study the role of the caspase-3 and nuclear factor kappa B (NF-κB) pathways in myenteric neurons in a P2X7 receptor knockout (KO) mouse model of IBDs.

METHODS

Forty male wild-type (WT) C57BL/6 and P2X7 receptor KO mice were euthanized 24 h or 4 d after colitis induction by 2,4,6-trinitrobenzene sulfonic acid (colitis group). Mice in the sham groups were injected with vehicle. The mice were divided into eight groups (n = 5): The WT sham 24 h and 4 d groups, the WT colitis 24 h and 4 d groups, the KO sham 24 h and 4 d groups, and the KO colitis 24 h and 4 d groups. The disease activity index (DAI) was analyzed, the distal colon was collected for immunohistochemistry analyses, and immunofluorescence was performed to identify neurons immunoreactive (ir) for calretinin, P2X7 receptor, cleaved caspase-3, total caspase-3, phospho-NF-κB, and total NF-κB. We analyzed the number of calretinin-ir and P2X7 receptor-ir neurons per ganglion, the neuronal profile area (µm²), and corrected total cell fluorescence (CTCF).

RESULTS

Cells double labeled for calretinin and P2X7 receptor, cleaved caspase-3, total caspase-3, phospho-NF-κB, or total NF-κB were observed in the WT colitis 24 h and 4 d groups. The number of calretinin-ir neurons per ganglion was decreased in the WT colitis 24 h and 4 d groups compared to the WT sham 24 h and 4 d groups, respectively (2.10 ± 0.13 vs 3.33 ± 0.17, P < 0.001; 2.92 ± 0.12 vs 3.70 ± 0.11, P < 0.05), but was not significantly different between the KO groups. The calretinin-ir neuronal profile area was increased in the WT colitis 24 h group compared to the WT sham 24 h group (312.60 ± 7.85 vs 278.41 ± 6.65, P < 0.05), and the nuclear profile area was decreased in the WT colitis 4 d group compared to the WT sham 4 d group (104.63 ± 2.49 vs 117.41 ± 1.14, P < 0.01). The number of P2X7 receptor-ir neurons per ganglion was decreased in the WT colitis 24 h and 4 d groups compared to the WT sham 24 h and 4 d groups, respectively (19.49 ± 0.35 vs 22.21 ± 0.18, P < 0.001; 20.35 ± 0.14 vs 22.75 ± 0.51, P < 0.001), and no P2X7 receptor-ir neurons were observed in the KO groups. Myenteric neurons showed ultrastructural changes in the WT colitis 24 h and 4 d groups and in the KO colitis 24 h group. The cleaved caspase-3 CTCF was increased in the WT colitis 24 h and 4 d groups compared to the WT sham 24 h and 4 d groups, respectively (485949 ± 14140 vs 371371 ± 16426, P < 0.001; 480381 ± 11336 vs 378365 ± 4053, P < 0.001), but was not significantly different between the KO groups. The total caspase-3 CTCF, phospho-NF-κB CTCF, and total NF-κB CTCF were not significantly different among the groups. The DAI was recovered in the KO groups. Furthermore, we demonstrated that the absence of the P2X7 receptor attenuated inflammatory infiltration, tissue damage, collagen deposition, and the decrease in the number of goblet cells in the distal colon.

CONCLUSION

Ulcerative colitis affects myenteric neurons in WT mice but has a weaker effect in P2X7 receptor KO mice, and neuronal death may be associated with P2X7 receptor-mediated caspase-3 activation. The P2X7 receptor can be a therapeutic target for IBDs.

Shaoyao decoction restores the mucus layer in mice with DSS-induced colitis by regulating Notch signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Restoring the mucus layer is a potential strategy for treating ulcerative colitis (UC). Previous studies reported that a Chinese medicine formula Shaoyao Decoction (SYD) effectively improved UC. However, the role and mechanism of SYD in restoring the mucus layer are still vague.

AIM OF THE STUDY

This study aimed to research the therapeutical effects and unravel the involved mechanism of SYD on DSS-evoked UC.

MATERIALS AND METHODS

First, the constituents of SYD were detected by UPLC-QTOF-MS/MS. Then, the DSS-induced UC model was introduced to investigate the pharmacologic action and molecular mechanism of SYD on UC. Pharmacodynamic indicators were assessed including body weight, colon length, ulcerations, disease activity index (DAI), inflammatory cytokines and histological parameters. To investigate the integrality and functions of the mucous layer, AB-PAS stain and UEA-1 stain were used to evaluate the completeness of mucous layer, as well as the maturation of goblet cells (GCs). The bacterial invasion was detected by fluorescence in situ hybridization. As to mechanism exploration, the expressions of Notch/Hes1 pathway were investigated by using agonists in lipopolysaccharides (LPS) -stimulated LS174T cell.

RESULTS

After modeling in mice, SYD remarkedly ameliorated the symptoms of mouse colitis, the expression of pro-inflammatory factors declined, and increased IL-10 expression was observed in SYD-treated mice. Besides, SYD repaired the structure of the mucus layer and prevented bacterial invasion. Mechanism investigation discovered that SYD promoted GCs differentiation by inhibiting the Notch pathway, which was consistent with the results in LPS-challenged LS174 cell.

CONCLUSIONS

These findings demonstrated that SYD could restore the mucus layer to prevent UC via suppressing the Notch signaling pathway, which provided evidences for the UC treatment of SYD in the clinic.

Assessment of Nonalcoholic Fatty Liver Disease Symptoms and Gut-Liver Axis Status in Zebrafish after Exposure to Polystyrene Microplastics and Oxytetracycline, Alone and in Combination

BACKGROUND

Environmental pollution may give rise to the incidence and progression of nonalcoholic fatty liver disease (NAFLD), the most common cause for chronic severe liver lesions. Although knowledge of NAFLD pathogenesis is particularly important for the development of effective prevention, the relationship between NAFLD occurrence and exposure to emerging pollutants, such as microplastics (MPs) and antibiotic residues, awaits assessment.

OBJECTIVES

This study aimed to evaluate the toxicity of MPs and antibiotic residues related to NAFLD occurrence using the zebrafish model species.

METHODS

Taking common polystyrene MPs and oxytetracycline (OTC) as representatives, typical NAFLD symptoms, including lipid accumulation, liver inflammation, and hepatic oxidative stress, were screened after 28-d exposure to environmentally realistic concentrations of MPs (0.69mg/L) and antibiotic residue (3.00μg/L). The impacts of MPs and OTC on gut health, the gut-liver axis, and hepatic lipid metabolism were also investigated to reveal potential affecting mechanisms underpinning the NAFLD symptoms observed.

RESULTS

Compared with the control fish, zebrafish exposed to MPs and OTC exhibited significantly higher levels of lipid accumulation, triglycerides, and cholesterol contents, as well as inflammation, in conjunction with oxidative stress in their livers. In addition, a markedly smaller proportion of Proteobacteria and higher ratios of Firmicutes/Bacteroidetes were detected by microbiome analysis of gut contents in treated samples. After the exposures, the zebrafish also experienced intestinal oxidative injury and yielded significantly fewer numbers of goblet cells. Markedly higher levels of the intestinal bacteria-sourced endotoxin lipopolysaccharide (LPS) were also detected in serum. Animals treated with MPs and OTC exhibited higher expression levels of LPS binding receptor (LBP) and downstream inflammation-related genes while also exhibiting lower activity and gene expression of lipase. Furthermore, MP-OTC coexposure generally exerted more severe effects compared with single MP or OTC exposure.

DISCUSSION

Our results suggested that exposure to MPs and OTC may disrupt the gut-liver axis and be associated with NAFLD occurrence. https://doi.org/10.1289/EHP11600.

Intestinal homeostasis disruption in mice chronically exposed to arsenite-contaminated drinking water

Chronic exposure to inorganic arsenic [As(III) and As(V)] affects about 200 million people, and is linked to a greater incidence of certain types of cancer. Drinking water is the main route of exposure, so, in endemic areas, the intestinal mucosa is constantly exposed to the metalloid. However, studies on the intestinal toxicity of inorganic As are scarce. The objective of this study was to evaluate the toxicity of a chronic exposure to As(III) on the intestinal mucosa and its associated microbiota. For this purpose, BALB/c mice were exposed during 6 months through drinking water to As(III) (15 and 30 mg/L). Treatment with As(III) increased reactive oxygen species (43-64%) and lipid peroxidation (8-51%). A pro-inflammatory response was also observed, evidenced by an increase in fecal lactoferrin (23-29%) and mucosal neutrophil infiltration. As(III) also induced an increase in the colonic levels of pro-inflammatory cytokines (24-201%) and the activation of some pro-inflammatory signaling pathways. Reductions in the number of goblet cells and mucus production were also observed. Moreover, As(III) exposure resulted in changes in gut microbial alpha diversity but no differences in beta diversity. This suggested that the abundance of some taxa was significantly affected by As(III), although the composition of the population did not show significant alterations. Analysis of differential taxa agreed with this, 21 ASVs were affected in abundance or variability, especially ASVs from the family Muribaculaceae. Intestinal microbiota metabolism was also affected, as reductions in fecal concentration of short-chain fatty acids were observed. The effects observed on different components of the intestinal barrier may be responsible of the increased permeability in As(III) treated mice, evidenced by an increase in fecal albumin (48-66%). Moreover, serum levels of Lipopolysaccharide binding proteins and TNF-α were increased in animals treated with 30 mg/L of As(III), suggesting a low-level systemic inflammation.

Blocking Notch signalling reverses miR-155-mediated inflammation in allergic rhinitis

Although recent studies have shown that the Notch signalling pathway induces the production of Th2-related immune factors, the exact mechanism through which Notch signalling exacerbates allergic rhinitis (AR) remains unknown. To investigate the roles of Notch in AR, serum, nasal mucosa and spleen samples were isolated from BALB/c mice. Paraffin sections were stained with haematoxylin and eosin (H&E) or periodic acid-Schiff (PAS) to assess inflammation. Flow cytometry was performed to detect group 2 innate lymphoid cells (ILC2s) in the serum samples, and cytokine levels were measured by enzyme-linked immunosorbent assays (ELISAs). The mRNA expression levels of the Notch signalling pathway components and miR-155 were measured by quantitative real-time PCR (qRT-PCR). In addition, human nasal epithelial cells (HNEpCs) were cultured to investigate the functional consequences of Notch pathway inhibition. The findings demonstrated that symptomatology and pathology were substantially altered, and AR model mice were established. In vivo stimulation with ovalbumin (OVA) significantly increased the Th2-type immune responses and the expression of OVA-sIgE, IL-4, GATA3, NF-κB and miR-155. However, the Notch signalling pathway was significantly deteriorated in AR, and this effect was accompanied by reduced Notch1, Notch2, RBPj and Hes1 levels. These effects were abrogated by gamma-secretase inhibitor IX (DAPT) treatment, and DAPT inhibited the wound healing and proliferation of HNEpCs in a dose-dependent manner. Therefore, our results suggest that blocking the Notch pathway may alleviate miR-155-mediated inflammation via the regulation of immune homeostasis in AR.

Mogroside-rich extract from Siraitia grosvenorii fruits protects against heat stress-induced intestinal damage by ameliorating oxidative stress and inflammation in mice

Global warming makes humans and animals more vulnerable to heat stress. Heat stress can cause multiorgan dysfunction, especially in the intestine, primarily via oxidative stress and inflammation. Mogroside-rich extract (MGE) is the active ingredient of Siraitia grosvenorii and has significant antioxidant and anti-inflammatory activity. However, whether MGE can alleviate the intestinal damage caused by heat stress has not been explored. In this study, mice were given 600 mg kg^-1 MGE followed by exposure to high temperature (40 °C for 2 h per day), and the structures and molecular changes in the ileum were examined. Our findings showed that body weight was decreased by heat stress, while the activity of serum superoxide dismutase (SOD) was increased. We further found that heat stress impaired the intestinal barrier by reducing the number of goblet cells and mRNA levels of the tight junction proteins zona occludens protein 1 (ZO-1), Occludin (OCLD) and recombinant mucin 2 (MUC2 mucin), but it increased the mRNA level of trefoil factor 3 (TFF3). Interestingly, MGE treatment reversed these changes. Furthermore, heat stress increased the activity of SOD in the intestine, downregulated the expression of the oxidative stress-related genes glutathione peroxidase 1 (GPX1), SOD2 and nuclear factor erythroid 2-related factor 2 (NRF2), and upregulated the expression of catalase (CAT). Moreover, heat stress increased tumor necrosis factor-α (TNF-α) levels in the intestine and upregulated the expression of the inflammation-related genes interleukin 10 (IL-10), TNF-α, Interferon-γ (IFN-γ), toll like receptor 4 (TLR4) and nuclear factor-kappa B (NF-kB). However, MGE treatment effectively reduced TNF-α levels and restored the normal activity of SOD and normal mRNA levels for both oxidative stress-related and inflammation-related genes. In summary, our results showed that MGE can protect against heat stress-induced intestinal damage by ameliorating inflammation and oxidative stress.

Galacto-Oligosaccharides Increase the Abundance of Beneficial Probiotic Bacteria and Improve Gut Architecture and Goblet Cell Expression in Poorly Performing Piglets, but Not Performance

Poorly performing piglets receiving commercial milk replacers do not benefit from the naturally occurring probiotic galacto-oligosaccharides otherwise found in sow milk. Study objectives were to investigate the effects of complete milk replacer supplemented with galacto-oligosaccharides on the microbiome, gut architecture and immunomodulatory goblet cell expression of poorly performing piglets that could benefit from milk replacement feeding when separated from sows and housed with fit siblings in environmentally controlled pens. The study is novel in that it is one of the first to investigate the effects of supplementing complete milk replacer with galacto-oligosaccharides in poorly performing piglets. Gastrointestinal tract samples were collected from piglets, and the microbiome composition was assessed by 16s ribosomal ribonucleic acid gene sequencing. Gut architectural features, villus/crypt ratio and enumeration of goblet cells in tissues were assessed by histopathological techniques. The most abundant taxa identified at the genus level were Lactobacillus, Streptococcus, Prevotella, Lactococcus and Leuconostoc. Milk replacer plus galacto-oligosaccharides significantly improved gut architectural features and villus/crypt ratio throughout the gastrointestinal tract, increased the number of goblet cells and revealed a differential abundance of beneficial probiotic bacteria, particularly Lactobacillus and Bifidobacterium. In these respects, galacto-oligosaccharide-supplemented milk replacer may be a useful addition to animal husbandry in poorly performing, non-thriving animals when moved to environmentally controlled pens away from sows and fit siblings, thereby modulating the microbiome and gastrointestinal tract performance.

Alternative lung cell model systems for toxicology testing strategies: Current knowledge and future outlook

Due to the current relevance of pulmonary toxicology (with focus upon air pollution and the inhalation of hazardous materials), it is important to further develop and implement physiologically relevant models of the entire respiratory tract. Lung model development has the aim to create human relevant systems that may replace animal use whilst balancing cost, laborious nature and regulatory ambition. There is an imperative need to move away from rodent models and implement models that mimic the holistic characteristics important in lung function. The purpose of this review is therefore, to describe and identify the various alternative models that are being applied towards assessing the pulmonary toxicology of inhaled substances, as well as the current and potential developments of various advanced models and how they may be applied towards toxicology testing strategies. These models aim to mimic various regions of the lung, as well as implementing different exposure methods with the addition of various physiologically relevent conditions (such as fluid-flow and dynamic movement). There is further progress in the type of models used with focus on the development of lung-on-a-chip technologies and bioprinting, as well as and the optimization of such models to fill current knowledge gaps within toxicology.

Prebiotic activity of chitooligosaccharides and their ability to alleviate necrotizing enterocolitis in newborn rats

Chitooligosaccharides (COS) have many bioactive functions and favorable prospects in the fields of biomedicine and functional foods. In this study, COS was found to significantly improve the survival rate of neonatal necrotizing enterocolitis (NEC) model rats, alter the composition of the intestinal microbiota, inhibit the expression of inflammatory cytokines, and alleviate intestinal pathological injury. In addition, COS also increased the abundance of Akkermansia, Bacteroides, and Clostridium sensu stricto 1 in the intestines of normal rats (the normal rat model is more universal). The in vitro fermentation results found that COS was degraded by the human gut microbiota to promote the abundance of Clostridium sensu stricto 1 and produced numerous short-chain fatty acids (SCFAs). In vitro metabolomic analysis revealed that COS catabolism was associated with significant increases in 3-hydroxybutyrate acid and γ-aminobutyric acid. This study provides evidence for the potential of COS as a prebiotic in food products and to ameliorate NEC development in neonatal rats.

Alleviation of DSS-induced colitis in mice by a new-isolated Lactobacillus acidophilus C4

Introduction

Probiotic is adjuvant therapy for traditional drug treatment of ulcerative colitis (UC). In the present study, Lactobacillus acidophilus C4 with high acid and bile salt resistance has been isolated and screened, and the beneficial effect of L. acidophilus C4 on Dextran Sulfate Sodium (DSS)-induced colitis in mice has been evaluated. Our data showed that oral administration of L. acidophilus C4 remarkably alleviated colitis symptoms in mice and minimized colon tissue damage.

Methods

To elucidate the underlying mechanism, we have investigated the levels of inflammatory cytokines and intestinal tight junction (TJ) related proteins (occludin and ZO-1) in colon tissue, as well as the intestinal microbiota and short-chain fatty acids (SCFAs) in feces.

Results

Compared to the DSS group, the inflammatory cytokines IL-1β, IL-6, and TNF-α in L. acidophilus C4 group were reduced, while the antioxidant enzymes superoxide dismutase (SOD), glutathione (GSH), and catalase (CAT) were found to be elevated. In addition, proteins linked to TJ were elevated after L. acidophilus C4 intervention. Further study revealed that L. acidophilus C4 reversed the decrease in intestinal microbiota diversity caused by colitis and promoted the levels of SCFAs.

Discussion

This study demonstrate that L. acidophilus C4 effectively alleviated DSS-induced colitis in mice by repairing the mucosal barrier and maintaining the intestinal microecological balance. L. acidophilus C4 could be of great potential for colitis therapy.

Immunocytochemical characterization of ex vivo cultured conjunctival explants; marker validation for the identification of squamous epithelial cells and goblet cells

Tissue-engineered products are at the cutting edge of innovation considering their potential to functionally and structurally repair various tissue defects when the body's own regenerative capacity is exhausted. At the ocular surface, the wound healing response to extensive conjunctival damage results in tissue repair with structural alterations or permanent scar formation rather than regeneration of the physiological conjunctiva. Conjunctival tissue engineering therefore represents a promising therapeutic option to reconstruct the ocular surface in severe cicatrizing pathologies. During the rapid race to be a pioneer, it seems that one of the fundamental steps of tissue engineering has been neglected; a proper cellular characterization of the tissue-engineered equivalents, both morphologically and functionally. Currently, no consensus has been reached on an identification strategy and/or markers for the characterization of cultured squamous epithelial and goblet cells. This study therefore evaluated the accuracy of promising markers to identify differentiated conjunctival-derived cells in human primary explant cultures through immunocytochemistry, including keratins (i.e., K7, K13, and K19) and mucins (i.e., MUC1, MUC5AC, and PAS-positivity). Comparison of the in vivo and in vitro cellular profiles revealed that the widely used goblet cell marker K7 does not function adequately in an in vitro setting. The other investigated markers offer a powerful tool to distinguish cultured squamous epithelial cells (i.e., MUC1 and K13), goblet cells (i.e., MUC5AC and PAS-staining), and conjunctival-derived cells in general (i.e., K19). In conclusion, this study emphasizes the power alongside potential pitfalls of conjunctival markers to assess the clinical safety and efficacy of conjunctival tissue-engineered products.

Differentiated Epithelial Cells of the Gut

The intestine is a prime example of self-renewal where stem cells give rise to progenitor cells called transit-amplifying cells which differentiate into more specialized cells. There are two intestinal lineages: the absorptive (enterocytes and microfold cells) and the secretory (Paneth cells, enteroendocrine, goblet cells, and tuft cells). Each of these differentiated cell types has a role in creating an "ecosystem" to maintain intestinal homeostasis. Here, we summarize the main roles of each cell type.

Poly-β-hydroxybutyrate alleviated diarrhea and colitis via Lactobacillus johnsonii biofilm-mediated maturation of sulfomucin

Maintainance of sulfomucin is a key end point in the treatment of diarrhea and inflammatory bowel disease (IBD). However, the mechanisms underlying the microbial sense to sulfomucin are poorly understood, and to date, there are no therapies targeting the secretion and maturation of sulfomucin in IBD. Herein, we biosynthesized poly-β-hydroxybutyrate (PHB) and found that PHB could alleviate inflammation caused by diarrhea and colitis by enhancing the differentiation of sulfomucin. Microbiota transplantation and clearance together demonstrate that PHB promoting sulfomucin is mediated by Lactobacillus johnsonii (L. johnsonii). Further studies revealed that PHB provides a favorable niche for L. johnsonii biofilm formation to resist disturbance and support its growth. L. johnsonii-biofilm alleviates colitis by regulating fucose residues to promote goblet cell differentiation and subsequent sulfomucin maturation. Importantly, PHB alleviates colitis by enhancing sulfomucin secretion and maturation in a L. johnsonii-dependent manner. PHB represents a class of guardians, acting as a safe probiotic-biofilm delivery system that significantly promotes probiotic proliferation. Altogether, this study adds weight to the possible role of probiotics and functional materials in the treatment of intestinal inflammation. The application of PHB and biofilm self-coating L. johnsonii carries high translational potential and may be of clinical relevance.

Polyphenols from foxtail millet bran ameliorate DSS-induced colitis by remodeling gut microbiome

INTRODUCTION

Polyphenols from plants possess the anti-inflammatory and gut microbiota modulated properties. Foxtail millet (Setaria italica L., FM) has potential medical and nutritional functions because of rich phenolic and other phytochemical components.

METHODS

Here, the study explored the effects of bound polyphenol of inner shell (BPIS) from FM bran on dextran sodium sulfate (DSS)-induced experimental colitis mice.

RESULTS

Results showed that BPIS administration effectively relieved the weight loss, decreased disease active index (DAI) scores, restrained the secretion of pro-inflammatory cytokines TNF-α, IL-6 and IL-1β, increased anti-inflammatory cytokines IL-10, IL-4, IL-5. BPIS prevented gut barrier damage by enhancing tight junction proteins Claudin1, ZO-1 and Occludin, increasing the number of goblet cells and facilitating the gene expressions of mucin family. In addition, BPIS restored the gut microbiota composition and increased the relative abundance of commensal bacteria such as Lachnospiraceae and Rikenellaceae and restrained the growth of S24-7 and Staphylococcaceae. Concentrations of short-chain-fatty acids (SCFAs) generated by gut microbiota were elevated in BPIS treated colitis mice.

CONCLUSION

These data suggest that BPIS effectively ameliorates DSS-induced colitis by preventing intestinal barrier damage and promoting gut microbiota community.

Porcine Epidemic Diarrhea Virus: An Updated Overview of Virus Epidemiology, Virulence Variation Patterns and Virus-Host Interactions

The porcine epidemic diarrhea virus (PEDV) is a member of the coronavirus family, causing deadly watery diarrhea in newborn piglets. The global pandemic of PEDV, with significant morbidity and mortality, poses a huge threat to the swine industry. The currently developed vaccines and drugs are only effective against the classic GI strains that were prevalent before 2010, while there is no effective control against the GII variant strains that are currently a global pandemic. In this review, we summarize the latest progress in the biology of PEDV, including its transmission and origin, structure and function, evolution, and virus-host interaction, in an attempt to find the potential virulence factors influencing PEDV pathogenesis. We conclude with the mechanism by which PEDV components antagonize the immune responses of the virus, and the role of host factors in virus infection. Essentially, this review serves as a valuable reference for the development of attenuated virus vaccines and the potential of host factors as antiviral targets for the prevention and control of PEDV infection.

Intestinal cellular heterogeneity and disease development revealed by single-cell technology

The intestinal epithelium is responsible for food digestion and nutrient absorption and plays a critical role in hormone secretion, microorganism defense, and immune response. These functions depend on the integral single-layered intestinal epithelium, which shows diversified cell constitution and rapid self-renewal and presents powerful regeneration plasticity after injury. Derailment of homeostasis of the intestine epithelium leads to the development of diseases, most commonly including enteritis and colorectal cancer. Therefore, it is important to understand the cellular characterization of the intestinal epithelium at the molecular level and the mechanisms underlying its homeostatic maintenance. Single-cell technologies allow us to gain molecular insights at the single-cell level. In this review, we summarize the single-cell RNA sequencing applications to understand intestinal cell characteristics, spatiotemporal evolution, and intestinal disease development.

Thyroid hormone signaling in the intestinal stem cells and their niche

Several studies emphasized the function of the thyroid hormones in stem cell biology. These hormones act through the nuclear hormone receptor TRs, which are T3-modulated transcription factors. Pioneer work on T3-dependent amphibian metamorphosis showed that the crosstalk between the epithelium and the underlying mesenchyme is absolutely required for intestinal maturation and stem cell emergence. With the recent advances of powerful animal models and 3D-organoid cultures, similar findings have now begun to be described in mammals, where the action of T3 and TRα1 control physiological and cancer-related stem cell biology. In this review, we have summarized recent findings on the multiple functions of T3 and TRα1 in intestinal epithelium stem cells, cancer stem cells and their niche. In particular, we have highlighted the regulation of metabolic functions directly linked to normal and/or cancer stem cell biology. These findings help explain other possible mechanisms by which TRα1 controls stem cell biology, beyond the more classical Wnt and Notch signaling pathways.