Intestinal Receptor Research Articles

Probiotic-derived extracellular vesicles alleviate AFB1-induced intestinal injury by modulating the gut microbiota and AHR activation.

Aflatoxin B1 (AFB1) is a mycotoxin that widely found in the environment and mouldy foods. AFB1 initially targets the intestine, and AFB1-induced intestinal injury cannot be ignored. Lactobacillus amylovorus (LA), a predominant species of Lactobacillus, plays a role in carbohydrate metabolism. Extracellular vesicles (EVs), small lipid membrane vesicles, are widely involved in diverse cellular processes. However, the mechanism by which Lactobacillus amylovorus-QC1H-derived EVs (LA.EVs) protect against AFB1-induced intestinal injury remains unclear. In our study, a new strain named Lactobacillus amylovorus-QC1H (LA-QC1H) was isolated from pig faeces. Then, EVs derived from LA-QC1H were extracted via ultracentrifugation. Our results showed that LA.EVs significantly alleviated AFB1-induced intestinal injury by inhibiting the production of proinflammatory cytokines, decreasing intestinal permeability and increasing the expression of tight junction proteins. Moreover, 16S rRNA analysis revealed that LA.EVs modulated AFB1-induced gut dysbiosis in mice. However, LA.EVs did not exert beneficial effects in antibiotic-treated mice. LA.EVs treatment increased intestinal levels of indole-3-acetic acid (IAA) and activated intestinal aryl hydrocarbon receptor (AHR)/interleukin-22 (IL-22) signalling in AFB1-exposed mice. Inhibition of intestinal AHR signalling markedly weakened the protective effect of LA.EVs in AFB1-exposed mice. LA.EVs alleviated AFB1-induced intestinal injury by modulating the gut microbiota, activating the intestinal AHR/IL-22 signalling, reducing the inflammatory response and promoting intestinal barrier repair in mice.

TLR2/TLR5 Signaling and Gut Microbiota Mediate Soybean-Meal-Induced Enteritis and Declined Growth and Antioxidant Capabilities in Large Yellow Croaker (Larimichthys crocea)

Soybean meal, renowned for its high yield, cost efficiency, and protein richness, serves as a pivotal plant-based alternative to fish meal. However, high soybean meal inclusion in Larimichthys crocea diets is linked to enteritis and oxidative damage, with unknown mechanisms. Our study aims to elucidate the molecular basis of soybean-meal-induced enteritis and its impact on intestinal microbiota in L. crocea. To this end, four isonitrogenous and isolipidic diets with varying soybean meal levels (0% FM, 15% SBM15, 30% SBM30, and 45% SBM45) were administered to L. crocea for 8 weeks. The results indicated that the SBM30 and SBM45 treatments significantly hindered fish growth, digestive efficiency, and protein utilization. Furthermore, high soybean meal levels (SBM30 and SBM45) activated intestinal Toll-like receptors (TLR2A, TLR2B, TLR5, and TLR22), stimulating C-Rel and mTOR protein expression and elevating ERK phosphorylation. This led to increased pro-inflammatory cytokine production (IL-1β, IL-6, and TNF-α) and decreased anti-inflammatory cytokine expression (IL-4/13A, IL-4/13B, and TGF-β), suggesting a potential signaling pathway for soybean-meal-induced enteritis. Furthermore, enteritis induced by high soybean meal levels led to oxidative damage, evident from increased MDA levels and decreased antioxidant enzyme activities (SOD and CAT). The SBM30 and SBM45 treatments increased Firmicutes and Bacteroidetes abundance in fish gut microbiota, while Proteobacteria abundance decreased. This microbiota shift may enhance soybean meal nutrient utilization, yet high soybean meal concentrations still impair growth. A soybean-meal-rich diet promotes harmful bacteria like Rhodococcus and depletes probiotics like Ralstonia, increasing disease risks. L. crocea has limited tolerance for soybean meal, necessitating advanced processing to mitigate anti-nutritional factors. Ultimately, exploring alternative protein sources beyond soybean meal for fish meal replacement is optimal for L. crocea.

Transcutaneous auricular vagal nerve stimulation modulates blood glucose in ZDF rats via intestinal melatonin receptors and melatonin secretion

BackgroundMelatonin (MLT) and its receptor deficiency have been shown to be associated with type 2 diabetes mellitus (T2DM). Transcutaneous auricular vagus nerve stimulation (taVNS) is a non-invasive alternative intervention for patients suffering from hyperglycemia. Here, we aimed to investigate the role of taVNS on blood glucose modulation via intestinal melatonin receptors (MRs) and MLT secretion in hyperglycemia.MethodsAdult male Zucker diabetes fatty (ZDF) rats and Zucker lean (ZL) littermates were used. Forty ZDF rats were randomized into ZDF, taVNS, Px + taVNS and Lu + Px + taVNS groups (Px: pinealectomy, Lu: Luzindole). ZL rats served as a control group for comparison with ZDF rats without involvement in the taVNS intervention. Thirty min-taVNS interventions (2/15 Hz, 2 mA, 30 min/days) were administered once daily under anesthesia for 3 consecutive weeks in taVNS, Px + taVNS and Lu + Px + taVNS groups. Body weight and fasting blood glucose (FBG) were measured weekly in all rats, and real-time blood glucose was tested in the ZL and ZDF groups before, during and after the taVNS intervention. Plasma MLT concentration and the expression of MRs in the duodenum, jejunum and ileum were measured by the end of experiments.ResultsCompared with the ZL group, the level of FBG and body weight increased (all p < 0.01), plasma MLT secretion and the expression of MRs in duodenum, jejunum and ileum of ZDF rats decreased obviously (all p < 0.05), respectively. TaVNS can significantly reverse the hyperglycemia by regulating the non-pineal-derived MLT and MRs system in Px + taVNS group. Compared with the ZDF group, the expression of different intestinal MRs in the taVNS group was increased and more compactly arranged (both p < 0.05), the level of plasma MLT secretion was up-regulated (p < 0.01), and FBG and body weight were decreased (both p < 0.01). Meanwhile, after taVNS intervention in rats in the Px + taVNS group, we observed an increase in MLT secretion and the number of intestinal MRs compared with the taVNS group (all p > 0.05). In contrast, ZDF rats in which the pineal gland was excised by taVNS intervention and injected with the MRs antagonist Luzindole did not show these changes.ConclusionThe glucose reduction effect of taVNS may be related to regulating MLT levels and expressing intestinal MRs.

Bioengineered Nanomedicines Targeting the Intestinal Fc Receptor Achieve the Improved Glucoregulatory Effect of Semaglutide in a Type 2 Diabetic Mice Model.

The oral administration of the glucagon-like peptide-1 analogue, semaglutide, remains a hurdle due to its limited bioavailability. Herein, neonatal Fc receptor (FcRn)-targeted nanoparticles (NPs) were designed to enhance the oral delivery of semaglutide. The nanocarriers were covalently linked to the FcRn-binding peptide FcBP or the affibody molecule ZFcRn that specifically binds to the human FcRn (hFcRn) in a pH-dependent manner. These FcRn-targeted ligands were selected over the endogenous ligands of the receptor (albumin and IgG) due to their smaller size and simpler structure, which could facilitate the transport of functionalized NPs through the tissues. The capacity of FcRn-targeted semaglutide-NPs in controlling the blood glucose levels was evaluated in an hFcRn transgenic mice model, where type 2 diabetes mellitus (T2DM) was induced via intraperitoneal injection of nicotinamide followed by streptozotocin. The encapsulation of semaglutide into FcRn-targeted NPs was translated in an improved glucoregulatory effect in T2DM-induced mice when compared to the oral free semaglutide or nontargeted NP groups, after daily oral administrations for 7 days. Notably, a similar glucose-lowering response was observed between both FcRn-targeted NPs and the subcutaneous semaglutide groups. An increase in insulin pancreatic content and a recovery in β cell mass were visualized in the mice treated with FcRn-targeted semaglutide-NPs. The biodistribution of fluorescently labeled NPs through the gastrointestinal tract demonstrated that the nanosystems targeting the hFcRn are retained longer in the ileum and colorectum, where the expression of FcRn is more prevalent, than nontargeted NPs. Therefore, FcRn-targeted nanocarriers proved to be an effective platform for improving the pharmacological effect of semaglutide in a T2DM-induced mice model.

Involvement of Intestinal Epithelium Aryl Hydrocarbon Receptor Expression and 3, 3'-Diindolylmethane in Colonic Tertiary Lymphoid Tissue Formation.

Tertiary lymphoid tissues (TLTs) are adaptive immune structures that develop during chronic inflammation and may worsen or lessen disease outcomes in a context-specific manner. Immune cell activity governing TLT formation in the intestines is dependent on immune cell aryl hydrocarbon receptor (AhR) activation. Homeostatic immune cell activity in the intestines is further dependent on ligand activation of AhR in intestinal epithelial cells (IECs), yet whether AhR activation and signaling in IECs influences the formation of TLTs in the presence of dietary AhR ligands is not known. To this end, we used IEC-specific AhR deletion coupled with a mouse model of dextran sodium sulfate (DSS)-induced colitis to understand how dietary AhR ligand 3, 3'-diindolylmethane (DIM) influenced TLT formation. DIM consumption increased the size of TLTs and decreased T-cell aggregation to TLT sites in an IEC-specific manner. In DSS-exposed female mice, DIM consumption increased the expression of genes implicated in TLT formation (Interleukin-22, Il-22; CXC motif chemokine ligand 13, CXCL13) in an IEC AhR-specific manner. Conversely, in female mice without DSS exposure, DIM significantly reduced the expression of Il-22 or CXCL13 in iAhRKO mice, but this effect was not observed in WT animals. Our findings suggest that DIM affects the immunological landscape of TLT formation during DSS-induced colitis in a manner contingent on AhR expression in IECs and biological sex. Further investigations into specific immune cell activity, IEC-specific AhR signaling pathways, and dietary AhR ligand-mediated effects on TLT formation are warranted.

Structure and Function of Fermentation-Derived Bovine Lactoferrin Produced from Komagataella phaffii

Bovine lactoferrin (bLf) confers significant functional benefits for human health, but low concentrations in milk and high cost of commercial production limit availability and thus product application. Precision fermentation offers a solution to increase availability of biosimilar recombinant bLf (rbLf) thereby opening new opportunities for this high-value ingredient. To comply with regulatory requirements, we aimed to establish that rbLf from <i>K. phaffii</i> is substantially similar to native bLf in structure and key functions. Intact mass analysis showed a molecular weight of 84 kDa for rbLf, comparable to 82-83 kDa of bLf. LC-MS <i>N</i>-linked glycan profiling revealed predominantly high-mannose-based glycans on rbLf, similar to ~50% of bLf glycans. The isoelectric point and core amino acid sequence of rbLf and bLf are identical. rbLf retains the functional ability to bind and release iron, bind to intestinal Lf receptors, increase epithelial cell growth (>120% of control, P < 0.0001), reduce EPEC growth (>50% reduction, P < 0.0001), bind LPS (+4 fold, P < 0.001) and antagonize LPS-induced TLR4 activity (>40% reduction, P < 0.0001). These results demonstrate similarity of rbLf in structure and function to native bLf, supporting the effective application for expanded market opportunities for infant and adult health.

Disordered gut microbiota in postmenopausal stage amplifies intestinal tight junction damage to accelerate atherosclerosis.

The causes and characteristics of gut microbiota abnormalities and whether microbiota manipulation can prevent atherosclerosis in the postmenopausal stage remain to be determined. Aortic oestrogen receptor expression, histological changes and gut microbiota in women before and after menopause were detected. Serum oestrogen levels, systemic inflammation, intestinal oestrogen receptor expression and histological changes, atherosclerosis, and gut microbiota in low density lipoprotein deletion (LDLR-∕-) female mice before and after ovariectomy were tested. This study examined aortic oestrogen receptor expression, histological changes, and gut microbiota in women before and after menopause, and tested serum oestrogen levels, systemic inflammation, intestinal oestrogen receptor expression, histological changes, atherosclerosis, and gut microbiota in low-density lipoprotein receptor knockout (LDLR-∕-) female mice before and after ovariectomy. We demonstrated that the downregulation of oestrogen and oestrogen receptors after menopause promotes gut microbiota disturbance in both women and female mice. We found that gut microbiota disturbance amplifies the intestinal barrier damage and aggravates systemic inflammation, thereby promoting atherosclerosis in female mice. Faecal microbiota transplantation and antibiotics inhibit the proinflammatory properties of gut microbiota and prevent atherosclerosis by reducing intestinal barrier damage in postmenopausal mice. Together, our study highlights the causes of gut microbiota disturbances and the role of microbiota manipulation in preventing atherosclerosis in postmenopausal stage.

The genetic resistance of sows to Escherichia coli F4 adhesion reduces their response to a vaccine containing F4 fimbriae but does not affect the preweaning performance of their susceptible piglets.

Pigs without intestinal receptors for F4 fimbriae are congenitally resistant to F4 fimbriae-bearing enterotoxigenic Escherichia coli (ETEC F4). In general, 50 % and 100 % of piglets born to resistant (RR) sows crossed with hetero- or homozygous susceptible (SR, SS) boars, respectively, are susceptible but do not receive colostral antibodies against F4 fimbriae unless the sows have been vaccinated. The question arises as to whether resistant sows produce protective amounts of F4 antifimbrial antibodies after vaccination. The serum and colostrum antibody titres of 12 resistant and 12 susceptible vaccinated gilts were compared. The effect of the receptor status of the dam and sire on the preweaning performance of 5027 piglets was evaluated using Agroscope's recordings. The sows of the experimental herd, where ETEC F4 was circulating, were vaccinated against ETEC twice during the first pregnancy and once during each following pregnancy. The log2 transformed F4 antibody titres in the serum obtained after the second vaccine injection as well as in the colostrum of the 12 resistant animals were lower than the titres of the susceptible animals (serum: F4ab 11,19 ± 1,44 vs. 12,18 ± 1,33, P = 0,096; F4ac 10,03 ± 1,58 vs. 11,59 ± 1,43, P = 0,019; colostrum: F4ab 12,20 ± 2,41 vs. 14,02 ± 1,31, P = 0,033; F4ac 10,93 ± 2,46 vs. 13,03 ± 5,21, P = 0,006). The heat labile enterotoxin (LT) antibody titres after vaccination did not differ between susceptible and resistant animals (p > 0,10). Preweaning mortality in the offspring of RR sows × SS boars was slightly lower than in the offspring of SS sows × RR boars (P = 0,04), suggesting that the disease risk of susceptible piglets born to vaccinated resistant sows was not increased, even though they received colostrum with a slightly reduced content of antibody against F4 fimbriae.

Cyclic Peptides KS-133 and KS-487 Multifunctionalized Nanoparticles Enable Efficient Brain Targeting for Treating Schizophrenia.

Establishing drug delivery systems (DDSs) for transporting drugs from peripheral tissues to the brain is crucial for treating central nervous system diseases. We previously reported the interactions of (1) KS-133, a selective antagonist peptide, with vasoactive intestinal peptide receptor 2 (VIPR2), a drug target for schizophrenia, and (2) KS-487, a selective binding peptide, with the cluster IV domain of low-density lipoprotein receptor-related protein 1 (LRP1), which is involved in crossing the blood-brain barrier. We developed a novel DDS-based strategy for treating schizophrenia using KS-487 as a brain-targeting peptide and KS-133 as a drug. Dibenzocyclooctyne-KS-487 was conjugated with N3-indocyanine green (ICG) using a click reaction and administered intravenously into mice. Fluorescence was clearly observed from ICG in the brains of the mice. Nanoparticles (NPs) encapsulating ICG and displaying KS-487 were prepared and subcutaneously administered to mice, resulting in a significant accumulation of ICG in the brain. Pharmacokinetic analysis of NPs containing KS-133 and displaying KS-487 (KS-133/KS-487 NPs) revealed the time-dependent transport of KS-133 into the brain. KS-133/KS-487 NPs were subcutaneously administered to mouse models of schizophrenia, which significantly improved cognitive dysfunction. This is the first study to demonstrate the potential therapeutic efficacy of a multifunctionalized multipeptide NP in inhibiting VIPR2.

Increased intestinal permeability and lipopolysaccharide contribute to swainsonine-induced systemic inflammation

Long-term consumption of swainsonine could be poisonous to livestock, including facilitating apoptosis by impairing lysosomal function and inhibiting autophagic degradation, leading to liver inflammation and even death in livestock. However, the mechanism by swainsonine induced systemic inflammatory responses remained unclear, especially the effects of swainsonine on intestinal permeability, lipopolysaccharide (LPS) level and oxidative stress response were unknown. In this study, swainsonine increased intestinal permeability as evidenced by the significant down-regulation of colonic goblet cells, Akkermansia muciniphila and intestinal tight junction protein Occludin, Claudin 1 and ZO-1, and the significant up-regulation of mRNA expression level of the intestinal permeability indicator protein tyrosine phosphatase receptor type H (Ptprh) in the ileum of mice. Simultaneously, the elevated LPS biosynthetic genes in intestinal microbiota and increased intestinal permeability facilitated more bacterial endotoxin LPS to enter the blood. High concentration of free-form LPS induced high levels of proinflammatory cytokines and oxidative stress response, thereby causing the systemic inflammation. These findings provided a new perspective on swainsonine-induced systemic inflammation, suggesting that intestinal permeability and free-form LPS level may be the potential trigger factors.

Inulin Supplementation Alleviates Ochratoxin A-Induced Kidney Injury through Modulating Intestinal Microbiota.

Ochratoxin A (OTA) is a prevalent mycotoxin found in feed that causes significant kidney injury in animals. Further investigation was needed to devise strategies for treating OTA-induced kidney damage through the gut-kidney axis. Evidence indicates the crucial role of intestinal microbiota in kidney damage development. Inulin, a dietary fiber, protects kidneys by modulating intestinal microbiota and promoting short-chain fatty acid (SCFA) production. However, its precise mechanism in OTA-induced kidney damage remained unclear. In this study, chickens were orally administered OTA and inulin for 2 weeks to investigate inulin's effects on OTA-induced kidney damage and underlying mechanisms. The alteration of intestinal microbiota, SCFAs contents, and SCFA receptors was further analyzed. Results demonstrated that inulin supplementation influenced intestinal microbiota, increased SCFAs production, and mitigated OTA-induced kidney damage in chickens. The importance of microbiota in mediating inulin's renal protection was further confirmed by antibiotic and fecal microbiota transplantation experiments. Additionally, inulin exhibited antioxidant and anti-inflammatory properties, alleviating NLRP3 inflammasome activation and pyroptosis. In summary, inulin protected chickens from OTA-induced kidney damage, which might provide a potential strategy to mitigate the harmful effects of mycotoxins through prebiotics and safeguard renal health.

Uncovering chikungunya virus-encoded miRNAs and host-specific targeted genes associated with antiviral immune responses: an integrated bioinformatics approach

Chikungunya virus (CHIKV) is a single-stranded RNA virus belonging to the genus Alphavirus and is responsible for causing Chikungunya fever, a type of arboviral fever. Despite extensive research, the pathogenic mechanism of CHIKV within host cells remains unclear. In this study, an in-silico approach was used to predict that CHIKV produces micro-RNAs that target host-specific genes associated with host cellular regulatory pathways. Putative micro-RNAs of CHIKV were predicted using the miRNAFold and Vmir RNA structure web servers, and secondary structure prediction was performed using RNAfold. Host-specific target genes were then predicted, and hub genes were identified using CytoHubba and module selection through MCODE. Functional annotations of hub genes revealed their association with various pathways, including osteoclast differentiation, neuroactive ligand-receptor interaction, and mRNA surveillance. We used the freely available dataset GSE49985 to determine the level of expression of host-specific target genes and found that two genes, F-box and leucine-rich repeat protein 16 (FBXL16) and retinoic acid receptor alpha (RARA), were down-regulated, while four genes, RNA binding protein with serine-rich domain 1 (RNPS1), RNA helicase and ATPase (UPF1), neuropeptide S receptor 1 (NPSR1), and vasoactive intestinal peptide receptor 1 (VIPR1), were up-regulated. These findings provide insight into novel miRNAs and hub genes associated with CHIKV infection and suggest potential targets for therapeutic intervention. Further experimental validation of these targets could lead to the development of effective treatments for CHIKV-mediated diseases.

Pterostilbene Alleviates Dextran Sodium Sulfate (DSS)-Induced Intestinal Barrier Dysfunction Involving Suppression of a S100A8-TLR-4-NF-κB Signaling Cascade.

Intestinal barrier hemostasis is the key to health. As a resveratrol analogue, pterostilbene (PT) has been reported to prevent dextran sodium sulfate (DSS)-induced intestinal barrier dysfunction mainly associated with the intestinal NF-κB signaling pathway. However, the exact underlying mechanisms are not yet well-defined yet. In this study, we performed RNA-sequencing analysis and unexpectedly found that alarmin S100A8 sensitively responded to DSS-induced intestinal injury. Accordingly, histologic assessments suggested that the high expression of S100A8 was accompanied by increased intestinal infiltration of macrophages, upregulated intestinal epithelial Toll-like receptor 4 (TLR-4), and activated NF-κB signaling pathway. Interestingly, the above phenomena were effectively counteracted upon the addition of PT. Furthermore, by using a coculture system of macrophage THP-1 cells and HT-29 colon cells, we identified macrophage-secreted S100A8 activated intestinal epithelial NF-κB signaling pathway through TLR-4. Taken together, these findings suggested that PT ameliorated DSS-induced intestinal barrier injury through suppression of the macrophage S100A8-intestinal epithelial TLR-4-NF-κB signaling cascade.

Neuro-intestinal acetylcholine signalling regulates the mitochondrial stress response in Caenorhabditis elegans

Neurons coordinate inter-tissue protein homeostasis to systemically manage cytotoxic stress. In response to neuronal mitochondrial stress, specific neuronal signals coordinate the systemic mitochondrial unfolded protein response (UPRmt) to promote organismal survival. Yet, whether chemical neurotransmitters are sufficient to control the UPRmt in physiological conditions is not well understood. Here, we show that gamma-aminobutyric acid (GABA) inhibits, and acetylcholine (ACh) promotes the UPRmt in the Caenorhabditis elegans intestine. GABA controls the UPRmt by regulating extra-synaptic ACh release through metabotropic GABAB receptors GBB-1/2. We find that elevated ACh levels in animals that are GABA-deficient or lack ACh-degradative enzymes induce the UPRmt through ACR-11, an intestinal nicotinic α7 receptor. This neuro-intestinal circuit is critical for non-autonomously regulating organismal survival of oxidative stress. These findings establish chemical neurotransmission as a crucial regulatory layer for nervous system control of systemic protein homeostasis and stress responses.

Quantifying Forms and Functions of Enterohepatic Bile Acid Pools in Mice

Backgrounds & AimsBile acids (BAs) are core gastrointestinal metabolites with dual functions in lipid absorption and cell signaling. BAs circulate between the liver and distal small intestine (i.e., ileum), yet the dynamics through which complex BA pools are absorbed in the ileum and interact with host intestinal cells in vivo remain poorly understood. As ileal absorption is rate-limiting in determining which BAs in the intestinal lumen gain access to host intestinal cells and receptors, and at what concentrations, we hypothesized that defining the rates and routes of ileal BA absorption in vivo would yield novel insights into the physiological forms and functions of mouse enterohepatic BA pools. MethodsUsing ex vivo mass spectrometry, we quantified 88 BA species and metabolites in the intestinal lumen and superior mesenteric vein of individual wild type mice, as well as cage-mates lacking the ileal BA transporter, Asbt/Slc10a2. ResultsUsing these data, we calculated that the pool of BAs circulating through ileal tissue (i.e., the ‘ileal BA pool’) in fasting C57BL/6J female mice is ∼0.3 μmoles/g. Asbt-mediated transport accounted for ∼80% of this pool and amplified size. Passive permeability explained the remaining ∼20% and generated diversity. Compared with wild type mice, the ileal BA pool in Asbt-deficient mice was ∼5-fold smaller, enriched in secondary BA species and metabolites normally found in the colon, and elicited unique transcriptional responses upon addition to ex vivo-cultured ileal explants. ConclusionsThis study defines quantitative traits of the mouse enterohepatic BA pool and reveals how aberrant BA metabolism can impinge directly on host intestinal physiology.

Acquired dysfunction of CFTR underlies cystic fibrosis-like disease of the canine gallbladder.

Mucocele formation in dogs is a unique and enigmatic muco-obstructive disease of the gallbladder caused by the amassment of abnormal mucus that bears striking pathological similarity to cystic fibrosis. We investigated the role of cystic fibrosis transmembrane conductance regulatory protein (CFTR) in the pathogenesis of this disease. The location and frequency of disease-associated variants in the coding region of CFTR were compared using whole genome sequence data from 2,642 dogs representing breeds at low-risk, high-risk, or with confirmed disease. Expression, localization, and ion transport activity of CFTR were quantified in control and mucocele gallbladders by NanoString, Western blotting, immunofluorescence imaging, and studies in Ussing chambers. Our results establish a significant loss of CFTR-dependent anion secretion by mucocele gallbladder mucosa. A significantly lower quantity of CFTR protein was demonstrated relative to E-cadherin in mucocele compared with control gallbladder mucosa. Immunofluorescence identified CFTR along the apical membrane of epithelial cells in control gallbladders but not in mucocele gallbladder epithelium. Decreases in mRNA copy number for CFTR were accompanied by decreases in mRNA for the Cl-/[Formula: see text] exchanger SLC26A3, K+ channels (KCNQ1, KCNN4), and vasoactive intestinal polypeptide receptor (VIPR1), which suggest a driving force for change in secretory function of gallbladder epithelial cells in the pathogenesis of mucocele formation. There were no significant differences in CFTR gene variant frequency, type, or predicted impact comparing low-risk, high-risk, and definitively diagnosed groups of dogs. This study describes a unique, naturally occurring muco-obstructive disease of the canine gallbladder, with uncanny similarity to cystic fibrosis, and driven by the underlying failure of CFTR function.NEW & NOTEWORTHY Cystic fibrosis transmembrane conductance regulatory protein (CFTR) genomic variants and expression of mRNA, protein, and electrogenic anion secretory activity of CFTR were characterized in dog gallbladder. Acquired inhibition of CFTR expression by gallbladder epithelium was identified as underpinning a naturally occurring muco-obstructive disease of the dog gallbladder that bears striking pathological similarity to animal models of cystic fibrosis.

Gene Expression Level and Immunohistochemical Localization of Cannabinoid and Cannabinoid-Related Receptors in The Small Intestine of Holstein Bulls (Bos Taurus Taurus)

Abstract The gastrointestinal tract plays a crucial role in nutrient absorption, secretion, and motility, ensuring proper digestion and overall homeostasis. Regulation of this complex system involves the coordination of various communication pathways, including neural and humoral mechanisms. One such mechanism is the endocannabinoid system (ECS), a signaling network comprising endogenous cannabinoids, receptors, and enzymes involved in the regulation of physiological processes in mammals and non-mammalian species. While extensive research has been conducted on the ECS in monogastric animals, limited information is available on its presence and distribution in cattle. This study aimed to investigate the distribution and localization patterns of cannabinoid receptors type 1 (CB1R) and type 2 (CB2R) and transient receptor potential vanilloid type 1 (TRPV1) in the bovine small intestine. The study included immunohistochemical analysis of intestinal tissue samples from Polish Holstein-Friesian breed bulls. Gene expression levels of CNR1, CNR2, and TRPV1 genes, encoding CB1R, CB2R, and TRPV1, respectively, were quantified using qPCR analysis. The results showed that all three receptors were expressed in the bovine small intestine, with TRPV1 exhibiting a significant upregulation in the jejunum compared to the duodenum and ileum. Immunoreactivity for CB1R and CB2R was predominantly observed in neurons of the enteric plexuses, while TRPV1 immunolabeling was detected in both enteric neurons and duodenal Brunner’s glands. These findings may establish an anatomical foundation for further investigations, lending support to the potential therapeutic efficacy of cannabinoid receptor agonists in alleviating gastrointestinal motility disorders associated with bovine enteropathies and optimizing milk production in dairy cattle.

Advancements in oral insulin: A century of research and the emergence of targeted nanoparticle strategies

AbstractWith the growing prevalence of diabetes, there is an urgent demand for a user‐friendly treatment option that minimizes side effects related to the use of subcutaneous injections. Scientists have dedicated over a century to developing an oral dosage form of insulin that can be administrated orally. The oral route of administration is the most desirable route for regularly dosed drugs in terms of safety and patient compliance. However, oral delivery of insulin remains a formidable challenge due to its intrinsically limited ability to cross the intestinal epithelium membrane and susceptibility to enzymatic degradation. This article reviews oral insulin research over the past decade, with a particular focus on surface modifications of nanoparticles (NPs). Various strategies involving controlling surface charges, utilizing protective proteins, and targeting specific receptors with ligands have been explored. Notably, surface modifications of the NPs for targeting specific intestinal receptors have shown promise in enhancing insulin oral absorption and bioavailability. Advanced technologies such as oral microneedles and gene therapy have also been developed, but their safety requires further assessment. Despite encouraging preclinical results across numerous strategies, the current clinical evidence is less optimistic. In summary, the present findings highlight the substantial journey that still lies ahead before achieving successful oral delivery of insulin.Practical Applications: This review provides a summary of recent progress in oral insulin delivery, particularly highlighting surface‐modified functional nanoparticles serving as an effective drug delivery system, which offers valuable information to the researchers. Due to the limited effectiveness of oral protein drugs caused by biological barriers, innovative technologies and drug delivery systems have been developed to overcome these obstacles and achieve therapeutic goals. This review concluded that surface modifications to nanoparticles can improve insulin stability and permeability, thereby enhancing oral bioavailability. It could assist researchers in developing more effective and patient‐friendly oral drug delivery systems.

Intestinal Taste Receptor Expression and Its Implications for Health: An Integrative Analysis in Female Rats after Chronic Insect Supplementation.

Taste receptors are found in the gastrointestinal tract, where they are susceptible to dietary modulation, a key point that is crucial for diet-related responses. Insects are sustainable and good-quality protein sources. This study analyzed the impact of insect consumption on the modulation of taste receptor expression across various segments of the rat intestine under healthy or inflammatory conditions. Female Wistar rats were supplemented with Tenebrio molitor (T) or Alphitobius diaperinus (B), alongside a control group (C), over 21 days under healthy or LPS-induced inflammation. The present study reveals, for the first time, that insect consumption modulates taste receptor gene expression, mainly in the ascending colon. This modulation was not found under inflammation. Integrative analysis revealed colonic Tas1r1 as a key discriminator for insect consumption (C = 1.04 ± 0.32, T = 1.78 ± 0.72, B = 1.99 ± 0.82, p-value <0.05 and 0.01, respectively). Additionally, correlation analysis showed the interplay between intestinal taste receptors and metabolic and inflammatory responses. These findings underscore how insect consumption modulates taste receptors, influencing intestinal function and broader physiological mechanisms.

Production of Histamine by Diverse Gut Bacteria Can Activate Intestinal HRH1 and Promote Calcium Mobilization

Background: Histamine is a biogenic amine that impacts several physiological processes, including allergic reactions, neurotransmitter activity and immune regulation. Bacteria uptake L-histidine and convert it into histamine via the activity of histidine decarboxylase enzymes. Histamine can also be produced by host cells such as enterochromaffn-like cells, mast cells and neurons. We hypothesized that a diverse group of bacteria would be capable of generating histamine. We predicted that histamine producing bacteria in the gut would activate intestinal epithelial histamine receptors and promote gut health. Methods and Results: To investigate how widespread histamine production is across bacterial species, we examined 102,018 annotated genomes in the Integrated Microbiome Genome Database. We found 3,679 bacterial genomes (3.6%) possessed histidine decarboxylase. We found histidine decarboxylase in bacteria belonged to 9 phyla: Bacillota, Bacteroidota, Actinomycetota, Pseudomonadota, Lentisphaerota, Fusobacteriota, Armatimonadota, Cyanobacteriota, and Verrucomicrobiota. Although the majority of the identified bacteria were aquatic and terrestrial in origin, ~14% of the bacteria were from the human gut microbiota. We confirmed the ability of several gut bacteria to generate histamine in a chemically defined bacterial growth medium using liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based targeted metabolomics. Briefly, histamine and histidine quantification is performed using authentic analytical and stable-label deuterated internal standard compounds that are used to produce calibration curves that span a linear dynamic range of 0.977-1,000 ng/mL. We found higher concentrations of histamine produced by gut-associated Klebsiella aerogenes, Fusobacterium varium, Clostridium perfringens, Limosilactobacillus reuteri and Morganella morganii. To address the question if bacterial-derived histamine could activate intestinal epithelial histamine receptors in the gut, we examined histamine receptors in publicly available single cell RNAseq datasets. We found that HRH1 was expressed in all cell types of the small and large intestine. We did not observe any expression of HRH2, HRH3 or HRH4 in the gut epithelium. We confirmed this finding in human intestinal organoids derived from duodenum, jejunum, ileum and colon. HRH1 activation in airway epithelial cells is known to signal through MAPK and promote pro-inflammatory cytokine release. Using GCaMP6S transduced organoids, we found that multiple concentrations of histamine stimulated robust calcium mobilization. However, histamine did not alter the levels of phosphorylated MAPK members p38, JNK, ERK, CREB or AKT and did not stimulate the release of any of the 18 epithelial specific cytokines we examined. Conclusions: Our work reveals that gut bacteria are capable of generating histamine, and histamine in the gut can activate epithelial HRH1 to drive calcium signaling and other downstream signals. K01 DK123195 (M Engevik) K01 DK121869 (A Engevik F32 DK130288 (K Engevik) APS Postdoctoral Fellowship (K Engevik). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.