The small intestine is essential for digestion, nutrient absorption, immune regulation, and microbial balance. Its epithelial lining, containing specialized cells like Paneth cells and tuft cells, is crucial for maintaining intestinal homeostasis. Paneth cells produce antimicrobial peptides and growth factors that support microbial regulation and intestinal stem cells, while tuft cells act as chemosensors, detecting environmental changes and modulating immune responses. Along with immune cells such as intraepithelial lymphocytes, innate lymphoid cells, T cells, and macrophages, they form a strong defense system that protects the epithelial barrier. Disruptions in this balance contribute to chronic inflammation, microbial dysbiosis, and compromised barrier function-key features of inflammatory bowel disease, celiac disease, and metabolic syndromes. Furthermore, dysfunctions in the small intestine and immune cells are linked to systemic diseases like obesity, diabetes, and autoimmune disorders. Recent research highlights promising therapeutic strategies, including modulation of epithelial and immune cell functions, probiotics, and gene editing to restore gut health and address systemic effects. This review emphasizes the pivotal roles of small intestinal epithelia and immune cells in maintaining intestinal homeostasis, their involvement in disease development, and emerging treatments for intestinal and systemic disorders.
Humans ; Intestinal Mucosa/cytology* ; Intestine, Small/cytology* ; Animals ; Inflammatory Bowel Diseases/immunology* ; Celiac Disease/immunology* ; Paneth Cells/immunology*

Necrotizing enterocolitis (NEC) is an intestinal inflammatory and necrotic disease seen in premature infants, and remains the leading cause of death resulted from gastrointestinal diseases in premature infants. The specific pathogenesis of NEC is still unclear. In recent years, a lot of studies have reported that Toll-like receptor 4 (TLR4) plays a key role in the pathogenesis of NEC. TLR4, which is abundantly expressed in intestinal epithelial cells of premature infants, binds to bacterial lipopolysaccharide (LPS) to activate downstream signaling pathways, leading to disruption of intestinal epithelial integrity and bacterial translocation, resulting in intestinal ischemic necrosis and inflammatory responses, which may rapidly progress to severe sepsis, multiple organ dysfunction, and death. This paper reviews the mechanism of TLR4-related signaling pathways in intestinal epithelial injury and inflammatory responses in newborns with NEC, providing a reference to study new therapeutic targets for NEC.
Enterocolitis, Necrotizing/pathology* ; Toll-Like Receptor 4/metabolism* ; Humans ; Infant, Newborn ; Signal Transduction ; Inflammation/metabolism* ; Animals ; Intestines/immunology* ; Intestinal Mucosa/pathology* ; Infant, Premature

OBJECTIVES: To investigate the therapeutic effects of cimifugin on Crohn's disease (CD)-like colitis in mice and its possible mechanism. METHODS: Thirty adult male C57BL/6 mice were randomized equally into control group, 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced CD-like colitis model group, and cimifugin treatment (daily gavage at 12.5 mg/kg) group. The therapeutic effect of cimifugin was evaluated by observing changes in body weight, disease activity index (DAI) scores, colon length, histopathological inflammation scores, and inflammatory cytokine levels in the colonic mucosa. Intestinal barrier integrity in the mice was assessed using immunofluorescence assay and Western blotting for claudin-1 and ZO-1; T-helper (Th) cell subset ratios in the mesenteric lymph nodes were analyzed with flow cytometry. Network pharmacology, KEGG enrichment analysis and molecular docking were used to predict the targets of cimifugin and analyze the key pathways and cimifugin-MAPK protein interactions, which were validated by Western blotting in the mouse models. RESULTS: In mice with TNBS-induced colitis, cimifugin treatment significantly attenuated body weight loss and colon shortening, lowered DAI and histopathological scores, decreased IFN-γ and IL-17 levels, and increased IL-4 and IL-10 levels in the colonic mucosa. Cimifugin treatment also significantly improved TNBS-induced claudin-1 dislocation and reduction of goblet cells, upregulated claudin-1 and ZO-1 expressions, reduced Th1 and Th17 cell percentages, and increased Th2 and Treg cell percentages in the colonic mucosa of the mice. KEGG analysis suggested a possible connection between the effect of cimifugin and MAPK signaling, and molecular docking showed strong binding affinity between cimifugin and MAPK core proteins. Western blotting demonstrated significantly decreased phosphorylation levels of JNK, ERK, and p38 in the colonic mucosa of cimifugin-treated mouse models. CONCLUSIONS Cimifugin alleviates TNBS-induced CD-like colitis by repairing intestinal barrier damage and restoring Th1/Th2 and Th17/Treg balance via suppressing MAPK pathway activation.
Animals ; Mice, Inbred C57BL ; Male ; Mice ; Crohn Disease/immunology* ; Colitis/immunology* ; MAP Kinase Signaling System/drug effects* ; Trinitrobenzenesulfonic Acid ; T-Lymphocytes, Helper-Inducer/drug effects* ; Intestinal Mucosa ; Disease Models, Animal

OBJECTIVE: To observe the effect of moxibustion on small intestinal mucosal immune barrier in rats with diarrhea-predominant irritable bowel syndrome (IBS-D) and explore its underlying mechanisms. METHODS: Of 38 newborn rats from 4 healthy SPF pregnant rats, 12 neonatal rats were randomly selected in a normal group. IBS-D model was prepared by the combined measures for the rest rats, including neonatal maternal separation, acetic acid enema and chronic restraint stress. Twenty-four successfully-modeled rats were randomized into a model group and a moxibustion group, 12 rats in each one. In the moxibustion group, suspending moxibustion was delivered at bilateral "Tianshu" (ST25) and "Shangjuxu" (ST37), 20 min each time, once daily and for 7 consecutive days. Separately, before acetic acid enema (aged 35 days), after modeling (aged 45 days) and after intervention (aged 53 days), the body mass, loose stool rate (LSR) and and the minimum volume threshold when abdominal withdrawal reflex (AWR) scored 3 were observed in the rats of each group. After intervention (aged 53 days), using HE and PAS staining, the morphology of duodenum was observed, the length of villus and the depth of crypt were measured, the ratio of the length of villus to the depth of crypt was calculated; and the numbers of mucosal intraepithelial lymphocytes (IELs) and goblet cells were counted. With ELISA adopted, the contents of γ-interferon (IFN-γ), interleukin-4 (IL-4) and secretory immunoglobulin A (sIgA) in duodenal mucosa of rats were detected. The proportion of T cell subsets in duodenal mucosa was detected using flow cytometry. The microvilli and tight junctions of duodenal mucosal epithelial cells were observed by transmission electron microscopy, and the integrity of duodenal mucosa observed by scanning electron microscopy. RESULTS: Compared with the normal group, for the rats in the model group, the body mass, the minimum volume threshold when AWR scored 3, the length of duodenal villus and the the ratio of the length of villus to the depth of crypt, as well as the proportion of CD₈⁺ T subset were all reduced (P<0.01, P<0.05), the counts of goblet cells in duodenal mucosa decreased (P<0.01); LRS, the proportion of CD₄⁺ T subset and CD₄⁺/CD₈⁺, as well as the contents of IFN-γ, IL-4 and sIgA in duodenal mucosa and IFN-γ/IL-4 were all elevated (P<0.01); and the numbers of IELs rose (P<0.01). The morphology of duodenal mucosa was irregular, the villi got shorter, sparse and scattered, with uneven density. The morphology of epithelial cells was destroyed and the tight junctions damaged, with larger spaces. When compared with the model group, in the moxibustion group, the body mass, the minimum volume threshold when AWR scored 3, the length of duodenal villus and the ratio of the length of villus to the depth of crypt, as well as the counts of goblet cells in duodenal mucosa increased (P<0.01); LRS, the proportion of CD₄⁺ T subset, and CD₄⁺/CD₈⁺, as well as the contents of IFN-γ, IL-4 and sIgA in duodenal mucosa and IFN-γ/IL-4 were reduced (P<0.01); and the numbers of IELs was dropped (P<0.01). The morphology of duodenal mucosa was more regular, the villi were grew, got longer and arranged regularly, with even density. The morphology of epithelial cells was slightly destroyed, and the tight junctions partially damaged. CONCLUSION Moxibustion at "Tianshu" (ST25) and "Shangjuxu" (ST37) can reduce visceral hypersensitivity in IBS-D rats and relieve abdominal pain, diarrhea and other symptoms. Its effect mechanism may be related to the repair of small intestinal mucosal immune barrier and the improvement in the immune function in IBS-D.
Animals ; Irritable Bowel Syndrome/immunology* ; Rats ; Moxibustion ; Intestinal Mucosa/immunology* ; Female ; Diarrhea/therapy* ; Intestine, Small/immunology* ; Male ; Humans ; Rats, Sprague-Dawley ; Disease Models, Animal

OBJECTIVE: To observe the effects of electroacupuncture (EA) on inflammatory response and intestinal mucosal barrier in obese rats with insulin resistance, and to explore the mechanism of EA on improving insulin resistance in rats. METHODS: Among 45 Wistar male rats, 15 rats were randomly selected and fed with common diet. After eight weeks, 10 rats were randomly selected and divided into the normal group. The remaining 30 rats were fed with high-fat diet for 8 weeks to establish obesity model of rat, among 28 rats with successful model of obesity, 20 rats were randomly selected and divided into the model group and EA group, 10 rats in each one. At the same time, 3 rats in the model group and the EA group were randomly selected for hyperinsulinemia-euglycemic clamp operation to determine whether the insulin resistance model was successful. After model establishment, the rats in the EA group were intervented with EA at "Zhongwan" (CV 12), "Guanyuan" (CV 4), "Zusanli" (ST 36) and "Fenglong" (ST 40) with continuous wave, frequency of 2 Hz and intensity of 1 mA; "Zusanli" (ST 36) and "Fenglong" (ST 40) were used alternately on both sides; the needles were sustained for 10 min; EA was given once every other day, three times a week for a total of 8 weeks. During the intervention, the rats in the normal group and the model group were fixed but not intervented. The body mass and postprandial blood sugar were measured in each group before and after 8-week intervention. After 6-week intervention, 3 rats in each group were clamped to detect systemic insulin sensitivity. Before the rats were killed, blood was taken from the apex of the heart to detect the serum insulin content. After the rats were killed, the mRNA levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in liver and adipose tissue and occlidin and ZO-1 in colon tissue were detected by Real time-PCR; the protein expression levels of occludin and ZO-1 in colon tissue were detected by Western blot method. RESULTS: Compared with the normal group, the body mass, postprandial blood sugar and serum insulin content in the model group were increased significantly, the glucose infusion rate (GIR) was decreased significantly (all <0.01), the mRNA expressions of TNF- and IL-6 in liver and adipose tissue were increased (<0.05, <0.01), the mRNA and protein expressions of ZO-1 in colon tissue were decreased significantly (both <0.01), and the mRNA expression of occludin was significantly decreased (<0.01). Compared with the model group, the body mass, postprandial blood sugar, serum insulin content, mRNA expressions of TNF-a and IL-6 in liver and adipose tissue were significantly decreased (<0.01, <0.05), GIR was significantly increased (<0.01), and the mRNA and protein expressions of ZO-1 in colon tissue were increased (<0.01, <0.05). CONCLUSION EA could decrease blood sugar and increase insulin sensitivity. Its mechanism may be related to inhibiting the expression of inflammatory factors and improving intestinal mucosal barrier.
Acupuncture Points ; Animals ; Electroacupuncture ; Humans ; Insulin Resistance ; Intestinal Mucosa ; immunology ; Male ; Obesity ; complications ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Rats, Wistar

To understand the effects of Lactobacillus rhamnosus GG (ATCC 53103) on intestinal barrier function in pre-weaning piglets under normal conditions, twenty-four newborn littermate piglets were randomly divided into two groups. Piglets in the control group were orally administered with 2 mL 0.1 g/mL sterilized skim milk while the treatment group was administered the same volume of sterilized skim milk with the addition of viable L. rhamnosus at the 1st, 3rd, and 5th days after birth. The feeding trial was conducted for 25 d. Results showed that piglets in the L. rhamnosus group exhibited increased weaning weight and average daily weight gain, whereas diarrhea incidence was decreased. The bacterial abundance and composition of cecal contents, especially Firmicutes, Bacteroidetes, and Fusobacteria, were altered by probiotic treatment. In addition, L. rhamnosus increased the jejunal permeability and promoted the immunologic barrier through regulating antimicrobial peptides, cytokines, and chemokines via Toll-like receptors. Our findings indicate that oral administration of L. rhamnosus GG to newborn piglets is beneficial for intestinal health of pre-weaning piglets by improving the biological, physical, and immunologic barriers of intestinal mucosa.
Administration, Oral ; Animals ; Animals, Newborn ; Cytokines/genetics* ; Female ; Gastrointestinal Microbiome ; Immunity, Innate ; Intestinal Mucosa/immunology* ; Lacticaseibacillus rhamnosus ; Male ; Probiotics/administration & dosage* ; Signal Transduction ; Swine ; Weaning

BACKGROUND/AIMS: This animal study aimed to define the underlying cellular mechanisms of intestinal barrier dysfunction. METHODS: Rats were fed 4% with dextran sodium sulfate (DSS) to induce experimental colitis. We analyzed the sugars in 24-hour urine output by high pressure liquid chromatography. The expression of claudins, mannan-binding lectin (MBL), and MBL-associated serine proteases 2 (MASP-2) were detected in the colonic mucosa by immunohistochemistry; and apoptotic cells in the colonic epithelium were detected by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling method assay. RESULTS: The lactulose and sucralose excretion levels in the urine of rats with DSS-induced colitis were significantly higher than those in the control rats. Mannitol excretion was lower and lactulose/mannitol ratios and sucralose/mannitol ratios were significantly increased compared with those in the control group (p<0.05). Compared with the controls, the expression of sealing claudins (claudin 3, claudin 5, and claudin 8) was significantly decreased, but that of claudin 1 was increased. The expression of pore-forming claudin 2 was upregulated and claudin 7 was downregulated in DSS-induced colitis. The epithelial apoptotic ratio was 2.8%+/-1.2% in controls and was significantly increased to 7.2%+/-1.2% in DSS-induced colitis. The expression of MBL and MASP-2 in the intestinal mucosa showed intense staining in controls, whereas there was weak staining in the rats with colitis. CONCLUSIONS: There was increased intestinal permeability in DSS-induced colitis. Changes in the expression and distribution of claudins, increased epithelial apoptosis, and the MASP-2-induced immune response impaired the intestinal epithelium and contributed to high intestinal permeability.
Animals ; Apoptosis/*physiology ; Claudins/*metabolism ; Colitis/chemically induced/immunology/*physiopathology ; Colon/immunology/physiopathology ; Dextran Sulfate ; Intestinal Mucosa/*physiopathology ; Lactulose/metabolism ; Mannitol/metabolism ; Mannose-Binding Lectin/*immunology ; Permeability ; Rats ; Rats, Sprague-Dawley ; Sucrose/analogs & derivatives/metabolism ; Up-Regulation

No abstract available.
Animals ; Apoptosis/*physiology ; Claudins/*metabolism ; Colitis/*physiopathology ; Intestinal Mucosa/*physiopathology ; Mannose-Binding Lectin/*immunology

Inflammatory bowel disease (IBD) is a chronic progressive idiopathic inflammatory disorder that involves the digestive tract from the mouth to the anus. Over the past decades, many therapeutic strategies have been developed to manage IBD, but therapeutic strategies based only on relief of clinical symptoms have not changed the natural history of this disease entity. This underlines the importance of understanding the natural history of IBD itself. When we look at the natural history of Crohn's disease (CD), it first begins with inflammation of the intestinal mucosa and this inflammatory reaction proceeds to stenosing or penetrating reaction if not adequately controlled. However, it takes a considerable amount of time before mucosal inflammation proceeds to stenosis of the intestinal lumen or penetration into the adjacent bowel. Therefore, it can be expected that if proper care is given during that period, progression of CD to such a complicated disease could be prevented. Even though the concept of mucosal healing was introduced in the early 1990s, no correlation could be observed between healing of mucosal lesions and relief of clinical symptoms. However, the introduction of biologic agents targeting tumor necrosis factor has changed the way to treat IBD that is refractory to standard medications and has allowed us to aim for a new therapeutic goal, 'deep remission'. Further advances in biologic agents have provided highly effective treatments for IBD, making deep remission a realistic goal. Whether IBD patients may benefit by experiencing a 'deep' remission beyond the control of clinical symptoms need to be evaluated in further investigation. Nevertheless, it can be anticipated that attaining deep remission might ultimately have an impact on important outcomes such as the need for surgery and the quality of life.
Anti-Inflammatory Agents, Non-Steroidal/therapeutic use ; Antibodies, Monoclonal/therapeutic use ; Colitis, Ulcerative/drug therapy/metabolism/pathology ; Crohn Disease/drug therapy/metabolism/pathology ; Humans ; Inflammatory Bowel Diseases/drug therapy/metabolism/*pathology ; Intestinal Mucosa/metabolism/pathology ; Mesalamine/therapeutic use ; Tumor Necrosis Factor-alpha/immunology/metabolism

Abnormal levels of microRNA (miR)-155, which regulate inflammation and immune responses, have been demonstrated in the colonic mucosa of patients with inflammatory bowel diseases (IBD), although its role in disease pathophysiology is unknown. We investigated the role of miR-155 in the acquisition and maintenance of an activated phenotype by intestinal myofibroblasts (IMF), a key cell population contributing to mucosal damage in IBD. IMF were isolated from colonic biopsies of healthy controls, ulcerative colitis (UC) and Crohn's disease (CD) patients. MiR-155 in IMF was quantified by quantitative reverse transcription-PCR in basal condition and following exposure to TNF-alpha, interleukin (IL)-1beta, lipopolysaccharide (LPS) or TGF-beta1. The effects of miR-155 mimic or inhibitor transfection on cytokine release and suppressor of cytokine signaling 1 (SOCS1) expression were assessed by enzyme-linked immunosorbent assay and western blot, respectively. Regulation of the target gene SOCS1 expression by miR-155 was assessed using luciferase reporter construct. We found that miR-155 was significantly upregulated in UC as compared with control- and CD-derived IMF. Moreover, TNF-alpha and LPS, but not TGF-beta1 and IL-1beta, significantly increased miR-155 expression in IMF. Ectopic expression of miR-155 in control IMF augmented cytokines release, whereas it downregulated SOCS1 expression. MiR-155 knockdown in UC-IMF reduced cytokine production and enhanced SOCS1 expression. Luciferase reporter assay demonstrated that miR-155 directly targets SOCS1. Moreover, silencing of SOCS1 in control IMF significantly increased IL-6 and IL-8 release. In all, our data suggest that inflammatory mediators induce miR-155 expression in IMF of patients with UC. By downregulating the expression of SOCS1, miR-155 wires IMF inflammatory phenotype.
Adult ; Aged ; Cells, Cultured ; Colitis, Ulcerative/*genetics/immunology/*pathology ; Cytokines/immunology ; Female ; *Gene Expression Regulation ; Humans ; Intestinal Mucosa/immunology/metabolism/pathology ; Male ; MicroRNAs/*genetics ; Middle Aged ; Myofibroblasts/immunology/metabolism/*pathology ; Suppressor of Cytokine Signaling Proteins/*genetics ; Tumor Necrosis Factor-alpha/immunology ; Up-Regulation ; Young Adult