Developmental expression of STATs, nuclear factor-κB and inflammatory genes in the jejunum of piglets during weaning

Expression of STAT- and T-cell-related genes in women with first-line treatment of relapsing-remitting multiple sclerosis

Relapsing-remitting multiple sclerosis is associated with changes in Jak/STAT pathways in immune cells, but the influence of disease-modifying drugs on these pathways is poorly understood. The aim of this study was to evaluate the impact of first-line disease-modifying drugs used in treatment of RRMS on expression of the STAT pathway and T-cell-related genes in the blood and on serum concentrations of sgp130 and TGF-β1 in women, as well as on the level of phosphorylated STAT3 and STAT5 proteins in T cells of untreated patients and heathy controls. Expression of STAT1, STAT3, STAT5A, STAT5B, SOCS1, SOCS3, FOXP3, IKZF2, RORC and ICOS genes in the blood of untreated RRMS patients, in the blood of patients treated with interferon-β, glatiramer acetate, dimethyl fumarate or teriflunomide and in the blood of healthy controls was evaluated using droplet digital PCR. Serum concentrations of sgp130 and TGF-β1 were evaluated by ELISA. Phosphorylated STAT3 and STAT5 protein levels in T cells were evaluated by flow cytometry. STAT3 gene expression was significantly higher in untreated patients than in healthy control, but the level of phosphorylated STAT3 in T cells was significantly lower. Patients treated with interferon-β or dimethyl fumarate had significantly lower STAT3 gene expression. Patients treated with teriflunomide had higher STAT1 gene expression, than untreated patients. Patients treated with dimethyl fumarate also had significantly lower RORC gene expression than untreated patients. The study shows the impact of drugs used in first-line treatment of relapsing-remitting multiple sclerosis on expression of STAT and T-cell-related genes.

The formidable guardian: Type 3 immunity in the intestine of pigs

Well-intestinal health is crucial for better growth performance in pigs. Type 3 immunity, which is one of the three types of immune responses in mammals, plays a vital role in maintaining intestinal homoeostasis. Therefore, we initially introduce the type 3 immune cells in the intestine of pigs, including their distribution, development, and function. We then discuss the type 3 immune response under infection, encompassing bacterial, fungal, and viral infections. It also covers two major stresses in pigs: heat stress and weaning stress. Lastly, we discuss the effects of various nutrients and feed additives on the regulation of the type 3 immune response in pigs under infection. This review aims to contribute to the understanding of the interaction between infection and type 3 immunity in pigs and to illustrate how various nutrients modulate the type 3 immune response in pigs under diverse infections.

The Use of Fruit and Vegetable by-Products as Enhancers of Health Status of Piglets after Weaning: The Role of Bioactive Compounds from Apple and Carrot Industrial Wastes

At weaning, piglets are exposed to a large variety of stressors, from environmental/behavioral factors to nutritional stress. Weaning transition affects the gastrointestinal tract especially, resulting in specific disturbances at the level of intestinal morphology, barrier function and integrity, mucosal immunity and gut microbiota. All these alterations are associated with intestinal inflammation, oxidative stress and perturbation of intracellular signaling pathways. The nutritional management of the weaning period aims to achieve the reinforcement of intestinal integrity and functioning to positively modulate the intestinal immunity and that of the gut microbiota and to enhance the health status of piglets. That is why the current research is focused on the raw materials rich in phytochemicals which could positively modulate animal health. The composition analysis of fruit, vegetable and their by-products showed that identified phytochemicals could act as bioactive compounds, which can be used as modulators of weaning-induced disturbances in piglets. This review describes nutritional studies which investigated the effects of bioactive compounds derived from fruit (apple) and vegetables (carrot) or their by-products on the intestinal architecture and function, inflammatory processes and oxidative stress at the intestinal level. Data on the associated signaling pathways and on the microbiota modulation by bioactive compounds from these by-products are also presented.

Weaning stress and intestinal health of piglets: A review

Weaning is considered to be one of the most critical periods in pig production, which is related to the economic benefits of pig farms. However, in actual production, many piglets are often subjected to weaning stress due to the sudden separation from the sow, the changes in diet and living environment, and other social challenges. Weaning stress often causes changes in the morphology and function of the small intestine of piglets, disrupts digestion and absorption capacity, destroys intestinal barrier function, and ultimately leads to reduced feed intake, increased diarrhea rate, and growth retardation. Therefore, correctly understanding the effects of weaning stress on intestinal health have important guiding significance for nutritional regulation of intestinal injury caused by weaning stress. In this review, we mainly reviewed the effects of weaning stress on the intestinal health of piglets, from the aspects of intestinal development, and intestinal barrier function, thereby providing a theoretical basis for nutritional strategies to alleviate weaning stress in mammals in future studies.

A functional mutation associated with piglet diarrhea partially by regulating the transcription of porcine STAT3

The present study aimed to search for functional mutations within the promoter of porcine STAT3 and to provide causative genetic variants associated with piglet diarrhea. We firstly confirmed that STAT3 expressed higher in the small intestine than in the spleen, stomach and large intestine of SPF piglets, respectively (P < 0.05). Then, 10 genetic variations in the porcine STAT3 promoter region was identified by direct sequencing. Among them, three mutations SNP1: g.−870 G>A, SNP2: g.−584 A>C and a 6-bp Indel in the promoter region that displayed significant differential transcriptional activities were identified. Association analyses showed that SNP1: g.−870 G>A was significantly associated with piglet diarrhea (P < 0.05) and the GG animals had lower diarrhea score than AA piglets (P < 0.01) in both Min and Landrace population. Further functional analysis revealed that E2F6 repressed the transcriptional efficiency of STAT3 in vitro, by binding the G allele of SNP1. The present study suggested that SNP1: g.−870 G>A was a piglet diarrhea-associated variant that directly affected binding with E2F6, leading to changes in STAT3 transcription which might partially contribute to piglet diarrhea susceptibility or resistance.

Effects of Supplementation with a Quebracho Tannin Product as an Alternative to Antibiotics on Growth Performance, Diarrhea, and Overall Health in Early-Weaned Piglets

Simple Summary

The restriction of the use of antibiotics in swine production worldwide has influenced pork production efficiency. New in-feed additives must be sustainable, prevent diarrhea in early weaning piglets, and promote growth performance. Novel in-feed additives, probiotics, prebiotics, organic compounds, mineral salts and vegetable extract have been extensively studied; most have shown some limitations that discourage extensive use. We investigated the plant extract MGM-P (a quebracho tannin product) as an alternative animal feed additive to antibiotics. We considered its unique structure, antibacterial, antioxidant, radical scavenging, and anti-inflammatory activities, and sustainability. We began with a low-level addition trial; 0.3% MGM-P had a more robust effect than 0.2% MGM-P. The findings demonstrated that 0.3% MGM-P supplementation prevented diarrhea in 21-day-old weaned piglets, improving piglet health without adversely influencing growth performance. Practical studies of the mechanisms underlying the effects of MGM-P and the optimal amount for supplementation are needed to confirm our findings.

Abstract

This study assessed the feasibility of using a vegetable extract, MGM-P (quebracho tannin product), as an alternative to antibiotics for weaned piglets; it investigated MGM-P effects on growth performance, diarrhea, and overall health in early-weaned piglets. In total, 24 piglets were allocated to three treatment groups fed basal diets supplemented with 0, 0.2%, or 0.3% MGM-P for 20 days. The addition of 0.3% MGM-P to the diet of early-weaned piglets improved diarrhea incidence, hematological parameters, and intestinal mucosa structure. Furthermore, the addition of 0.2% or 0.3% MGM-P to the diet of early-weaned piglets did not affect their overall health. Importantly, MGM-P had no effects on average daily gain (ADG), average daily feed intake (ADFI), or feed conversion ratio (FCR). Gut morphology analysis showed that treatment with 0.3% MGM-P enhanced the jejunal villus height (p < 0.05) while reducing the ileal crypt depth (p < 0.05) and colon mucosal thickness (p < 0.05). Collectively, the findings suggested that the use of MGM-P as an alternative to dietary antibiotics could improve diarrhea incidence in early-weaned piglets without negative effects on growth performance or overall health.

Dietary high protein-induced diarrhea and intestinal inflammation by activation of NF-κB signaling in piglets

The present study aimed to investigate whether inflammation-associated responses in piglets are induced by high protein (HP) through activating nuclear factor kappa B (NF-κB) signaling. Sixteen piglets (35 d of age, Duroc × [Landrace × Yorkshire], weaned at d 21, initial BW = 9.70 ± 0.11 kg) were allocated to 18% and 26% CP (HP group) at random, comprising 8 replicate pens per treatment. The piglets were slaughtered to collect intestinal tissues when apparent, persistent, and stable diarrhea syndromes happened (on d 12). No significant differences were observed in their growth performance (P > 0.05), but reduction by 19.11%, 25.31%, 23.64% of ADFI, ADG, and G:F, respectively was detected in the HP group. The HP group had greater (P = 0.002) diarrhea rates. Furthermore, dietary HP had lower ileal villus height (VH; P = 0.048), ratio of villus height to crypt depth (VH/CD ratio; P = 0.016), and colonic CD (P = 0.034), as well as had the trend (P = 0.075) to reduce the ileal villus absorptive area. Moreover, HP diets significantly elevated the goblet cell numbers in the ileal villi (P = 0.016) and colonic crypts (P < 0.001) and up-regulated (P = 0.012) the mRNA expression of mucin2 (Muc2) in the ileum. In addition, HP diets increased the myeloperoxidase concentration in the ileum (P = 0.002) and colon (P = 0.007) of piglets. Dietary HP significantly down-regulated the mRNA expression of tumor necrosis factor-α (TNF-α; P < 0.001) in the ileum, induced nitric oxide synthase (iNOS; P = 0.040) and interleukin-22 (IL-22; P = 0.008) in the colon, and inclined to down-regulate interleukin-1β (IL-1β; P = 0.076) expression in the colon. The relative protein abundance of Galectin-3 (P = 0.046) in the colon and the ratio of phosphorylation NF-κB to NF-κB (p-NF-κB/NF-κB ratio) in the ileum of HP piglets were also greater (P = 0.038). These results suggest that dietary HP may cause diarrhea in piglets by activating NF-κB signaling induced intestinal inflammation.

Cytokines and Transgenic Matrix in Autoimmune Diseases: Similarities and Differences

Autoimmune diseases are increasingly recognized as disease entities in which dysregulated cytokines contribute to tissue-specific inflammation. In organ-specific and multiorgan autoimmune diseases, the cytokine profiles show some similarities. Despite these similarities, the cytokines have different roles in the pathogenesis of different diseases. Altered levels or action of cytokines can result from changes in cell signaling. This article describes alterations in the JAK-STAT, TGF-β and NF-κB signaling pathways, which are involved in the pathogenesis of multiple sclerosis and systemic lupus erythematosus. There is a special focus on T cells in preclinical models and in patients afflicted with these chronic inflammatory diseases.

Effects of antimicrobial peptide cathelicidin-BF on diarrhea controlling, immune responses, intestinal inflammation and intestinal barrier function in piglets with postweaning diarrhea

The objective was to evaluate the effects of antimicrobial peptide cathelicidin-BF (C-BF) treatment on diarrhea controlling, immune responses, intestinal inflammation, and intestinal barrier function in piglets with postweaning diarrhea. In this study, fifty-four weaned piglets with diarrhea were selected and treated with saline (control), C-BF or norfloxacin nicotinic (NFN) for 7 days. Here, we investigated the effects of C-BF on diarrhea controlling, growth performance, serum immune indicators, intestinal morphology, intestinal inflammation, and intestinal epithelial barrier function in the weaned piglets with diarrhea. The results showed that C-BF treatment decreased (P < 0.05) diarrheal index and increased (P < 0.05) average daily gain (ADG) and average daily feed intake (ADFI) compared with control group. C-BF treatment decreased (P < 0.05) levels of serum blood urea nitrogen (BUN) and aspartate aminotransferase (AST), but increased (P < 0.05) levels of serum A/G and alkaline phosphatase (ALP) compared with control group. The concentrations of IL-6, IL-8, tumor necrosis factor-α (TNF-α), and IgG were lower (P < 0.05), but IgA was greater (P < 0.05) for piglets treated by C-BF compared with those in control group. C-BF and NFN treatment decreased (P < 0.05) IL-6, IL-8, IL-22, IL-10 and transforming growth factor-β (TGF-β) production in the jejunum and ileum compared with the control group. C-BF treatment increased the expression levels of zonula occluden-1 (ZO-1), Occludin, and Claudin-1 in the jejunum and colon compared with the control group and the NFN group. In conclusion, these data indicate that C-BF treatment may be an effective therapeutic strategy for controlling post-weaning diarrhea, improving immune responses, attenuating intestinal inflammation and enhancing intestinal barrier function in piglets with postweaning diarrhea.

How microRNAs affect the PD-L1 and its synthetic pathway in cancer

Programmed cell death-ligand 1 (PD-L1) is a glycoprotein that is expressed on the cell surface of both hematopoietic and nonhematopoietic cells. PD-L1 play a role in the immune tolerance and protect self-tissues from immune system attack. Dysfunction of this molecule has been highlighted in the pathogenesis of tumors, autoimmunity, and infectious disorders. MicroRNAs (miRNAs) are endogenous molecules that are classified as small non-coding RNA with approximately 20-22 nucleotides (nt) length. The function of miRNAs is based on complementary interactions with target mRNA via matching completely or incompletely. The result of this function is decay of the target mRNA or preventing mRNA translation. In the past decades, several miRNAs have been discovered which play an important role in the regulation of PD-L1 in various malignancies. In this review, we discuss the effect of miRNAs on PD-L1 expression and consider the effect of miRNAs on the synthetic pathway of PD-L1, especially during cancers.

Multi-strain yeast fraction product supplementation can alleviate weaning stress and improve performance and health of piglets raised under low sanitary conditions

BACKGROUND

This study was conducted to evaluate the health benefits to weaning pigs, raised under low sanitary conditions, of dietary supplementation with a multi-strain yeast fraction product (Cyberlindnera jadinii and Saccharomyces cerevisiae). In total, 160 weaning pigs (7.21 ± 1.05 kg) were randomly allotted to two dietary treatments in a 6-week feeding trial. The dietary treatments included a corn-soybean meal-based basal diet (CON) and CON + 2 g kg^-1 multi-strain yeast fraction product (MsYF) during weeks 1-2 and 0.4 g kg^-1 MsYF during weeks 3-6.

RESULTS

The MsYF supplementation increased (P < 0.05) body weight (BW) at day 42 and average daily gain (ADG) during days 1-14 and days 1-42 (P < 0.05) compared to CON. The total tract digestibility of dry matter (DM), fecal Lactobacillus counts, and serum immunoglobulin G (IgG) concentration at day 42 were higher (P < 0.05) in pigs fed a MsYF supplemented diet. The concentration of serum haptoglobin in pigs receiving a MsYF-supplemented diet was higher (P < 0.05) at days 7, 14, and 42 than those receiving CON. The mRNA expression for INF-γ and TNF-α genes were lower (P < 0.05) at days 14 and 7 respectively and the expression of IL-6 and TLR-2 genes was lower (P < 0.01) at days 7 and 14 in pigs fed an MsFY supplemented diet than those fed CON.

CONCLUSION

Supplementation with a multi-strain yeast fraction product had a positive effect on ADG during the early post-weaning period and led to better health in weaning pigs. © 2019 Society of Chemical Industry.

The intestinal barrier in multiple sclerosis: implications for pathophysiology and therapeutics

Biological barriers are essential for the maintenance of homeostasis in health and disease. Breakdown of the intestinal barrier is an essential aspect of the pathophysiology of gastrointestinal inflammatory diseases, such as inflammatory bowel disease. A wealth of recent studies has shown that the intestinal microbiome, part of the brain-gut axis, could play a role in the pathophysiology of multiple sclerosis. However, an essential component of this axis, the intestinal barrier, has received much less attention. In this review, we describe the intestinal barrier as the physical and functional zone of interaction between the luminal microbiome and the host. Besides its essential role in the regulation of homeostatic processes, the intestinal barrier contains the gut mucosal immune system, a guardian of the integrity of the intestinal tract and the whole organism. Gastrointestinal disorders with intestinal barrier breakdown show evidence of CNS demyelination, and content of the intestinal microbiome entering into the circulation can impact the functions of CNS microglia. We highlight currently available studies suggesting that there is intestinal barrier dysfunction in multiple sclerosis. Finally, we address the mechanisms by which commonly used disease-modifying drugs in multiple sclerosis could alter the intestinal barrier and the microbiome, and we discuss the potential of barrier-stabilizing strategies, including probiotics and stabilization of tight junctions, as novel therapeutic avenues in multiple sclerosis.

Gene expression profiles of germ-free and conventional piglets from the same litter

Germ-free (GF) pigs have clear microbiological backgrounds, and are extensively used as large animal models in the biomedical sciences. However, investigations of the transcriptomic differences between GF and cesarean-derived conventional (CV) piglets are limited. To improve our understanding of GF pigs, and to increase the utility of pigs as an alternative non-rodent model, we used RNA sequencing to profile gene expression in five tissues (the oral mucosae, jejunum, colon, liver, and spleen) of four male GF piglets and four male CV piglets from the same litter. We identified 14 genes that were differentially expressed in all five tissues. Seven of these common differentially expressed genes (DEGs) were interferon-inducible genes, and all 14 were consistently downregulated in the GF piglets as compared to the CV piglets. Compared to the other tissues tested, the expression of transcription factors (TFs) in the colon was most affected by the absence of a microbiota. The expression patterns of immune-related genes were downregulated in the GF piglets as compared to the CV piglets, indicating that the intestinal microbiota influenced gene expression in other tissues besides the gut. Gene Ontology (GO) analysis indicated that, in pigs, the intestinal microbiota affected the expression of genes related to immune system function and development.

Chitosan-Zn Chelate Downregulates TLR4-NF-κB Signal Pathway of Inflammatory Response and Cell Death-Associated Proteins Compared to Inorganic Zinc

The study was conducted to investigate the effect of chitosan-zinc chelate (CS-Zn) on TLR4-NF-κB signaling pathway and cell death-associated proteins in a weanling pig model. A total of 90 weaned piglets were allotted to three dietary treatments (the dietary treatments were as follows: (1) experimental diet with supplemental ZnSO₄ (150 mg Zn/kg diet), (2) experimental diet with supplemental CS-Zn (150 mg Zn/kg diet), and (3) experimental diet with a supplemental mixture of chitosan and ZnSO₄ (150 mg/kg Zn; the content of chitosan was equal to CS-Zn, which is according to molar basis)). The feeding trial lasted 30 days. The results showed that compared with ZnSO₄ or CS+ZnSO₄, CS-Zn decreased the expressions of the cell death-associated proteins Beclin-1, and Cleaved-Caspase3 and the ratio of LC3II/LC3I. The intestinal expressions of TLR4 and its downstream signals NF-κB, IKKβ, and IκBα were down-regulated simultaneously. Moreover, the contents of pro-inflammatory cytokines IL-2, TNF-α, and IFN-γ were decreased. The results indicated that as organic zinc source, CS-Zn was more effective than ZnSO₄ and the mixture of chitosan and ZnSO₄ for inhibiting inflammatory response and decreasing the expressions of proteins associated with cell death. The great anti-inflammatory effect of CS-Zn was modulated by inhibiting the TLR4-NF-κB signaling pathway, and the effect of CS-Zn on down-regulating the expression of cell death-associated proteins might also closely be associated with the TLR4-NF-κB signaling pathway.

Dual inhibition of STAT1 and STAT3 activation downregulates expression of PD-L1 in human breast cancer cells

OBJECTIVES

Breast cancer is the most commonly diagnosed cancer, and it is a leading cause of cancer-related deaths in females worldwide. Triple-negative breast cancer (TNBC) constitutes 15% of breast cancer and shows distinct metastasis profiles with poor prognosis. Strong PD-L1 expression has been observed in some tumors, supporting their escape from immune surveillance. Targeting PD-L1 could be a promising therapeutic approach in breast cancer patients. We investigated potential molecular mechanisms for constitutive expression of PD-L1 by inhibiting upstream STAT1 and STAT3 signals.

METHODS

PD-L1 expression in three breast cancer cell lines was measured using quantitative PCR and western blotting. Activation of STAT1 and STAT3 was blocked using pharmacological inhibitors and siRNA. The mechanism underlying the constitutive expression of PD-L1 was investigated using ChIP and co-immunoprecipitation assays.

RESULTS

We found that individual inhibition of STAT1 and STAT3 activation partially downregulated PD-L1, while combined inhibition completely downregulated PD-L1 expression. Moreover, our results suggest that pSTAT1-pSTAT3 dimerize in cytosol and translocate to the nucleus, where they bind to PD-L1 promoter and induce PD-L1 expression.

CONCLUSION

These findings provide a rationale for combined targeting of STAT1 and STAT3 for the development of immune-based cancer therapies for down regulation of PD-L1 expression.

Valproic acid attenuates traumatic spinal cord injury-induced inflammation via STAT1 and NF-κB pathway dependent of HDAC3

BACKGROUND

Microglial polarization with M1/M2 phenotype shifts and the subsequent neuroinflammatory responses are vital contributing factors for spinal cord injury (SCI)-induced secondary injury. Nuclear factor-κB (NF-κB) is considered the central transcription factor of inflammatory mediators, which plays a crucial role in microglial activation. Lysine acetylation of STAT1 seems necessary for NF-kB pathway activity, as it is regulated by histone deacetylases (HDACs). There have been no studies that have explained if HDAC inhibition by valproic acid (VPA) affects the NF-κB pathway via acetylation of STAT1 dependent of HDAC activity in the microglia-mediated central inflammation following SCI. We investigated the potential molecular mechanisms that focus on the phenotypic transition of microglia and the STAT1-mediated NF-κB acetylation after a VPA treatment.

METHODS

The Basso-Beattie-Bresnahan locomotion scale, the inclined plane test, the blood-spinal cord barrier, and Nissl staining were employed to determine the neuroprotective effects of VPA treatment after SCI. Assessment of microglia polarization and pro-inflammatory markers, such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and interferon (INF)-γ was used to evaluate the neuroinflammatory responses and the anti-inflammatory effects of VPA treatment. Immunofluorescent staining and Western blot analysis were used to detect HDAC3 nuclear translocation, activity, and NF-κB signaling pathway activation to evaluate the effects of VPA treatment. The impact of STAT1 acetylation on NF-kB pathway and the interaction between STAT1 and NF-kB were assessed to evaluate anti-inflammation effects of VPA treatment and also whether these effects were dependent on a STAT1/NF-κB pathway to gain further insight into the mechanisms underlying the development of the neuroinflammatory response after SCI.

RESULTS

The results showed that the VPA treatment promoted the phenotypic shift of microglia from M1 to M2 phenotype and inhibited microglial activation, thus reducing the SCI-induced inflammatory factors. The VPA treatment upregulation of the acetylation of STAT1/NF-κB pathway was likely caused by the HDAC3 translocation to the nucleus and activity. These results indicated that the treatment with the VPA suppressed the expression and the activity of HDAC3 and enhanced STAT1, as well as NF-κB p65 acetylation following a SCI. The acetylation status of NF-kB p65 and the complex with NF-κB p65 and STAT1 inhibited the NF-kB p65 transcriptional activity and attenuated the microglia-mediated central inflammatory response following SCI.

CONCLUSIONS

These results suggested that the VPA treatment attenuated the inflammatory response by modulating microglia polarization through STAT1-mediated acetylation of the NF-κB pathway, dependent of HDAC3 activity. These effects led to neuroprotective effects following SCI.

STAT3 activation in infection and infection-associated cancer

The Janus kinase/signal transducers and activators for transcription (JAK/STAT) pathway plays crucial roles in regulating apoptosis, proliferation, differentiation, and the inflammatory response. The JAK/STAT families are composed of four JAK family members and seven STAT family members. STAT3 plays a key role in inducing and maintaining a pro-carcinogenic inflammatory microenvironment. Recent evidence suggests that STAT3 regulates diverse biological functions in pathogenesis of diseases, such as infection and cancer. In the current review, we will summarize the research progress of STAT3 activation in infection and cancers. We highlight our recent study on the novel role of STAT3 in Salmonella infection-associated colon cancer. Infection with bacterial AvrA-expressing Salmonella activates the STAT3 pathway, which induces the β-catenin signals and enhances colonic tumorigenesis. STAT3 may be a promising target in developing prevention and treatment for infectious diseases and infection-associated cancers.

Cathelicidin-WA Improves Intestinal Epithelial Barrier Function and Enhances Host Defense against Enterohemorrhagic Escherichia coli O157:H7 Infection

Impaired epithelial barrier function disrupts immune homeostasis and increases inflammation in intestines, leading to many intestinal diseases. Cathelicidin peptides suppress intestinal inflammation and improve intestinal epithelial barrier function independently of their antimicrobial activity. In this study, we investigated the effects of Cathelicidin-WA (CWA) on intestinal epithelial barrier function, as well as the underlying mechanism, by using enterohemorrhagic Escherichia coli (EHEC)-infected mice and intestinal epithelial cells. The results showed that CWA attenuated EHEC-induced clinical symptoms and intestinal colitis, as did enrofloxacin (Enro). CWA decreased IL-6 production in the serum, jejunum, and colon of EHEC-infected mice. Additionally, CWA alleviated the EHEC-induced disruption of mucin-2 and goblet cells in the intestine. Interestingly, CWA increased the mucus layer thickness, which was associated with increasing expression of trefoil factor 3, in the jejunum of EHEC-infected mice. CWA increased the expression of tight junction proteins in the jejunum of EHEC-infected mice. Using intestinal epithelial cells and a Rac1 inhibitor in vitro, we demonstrated that the CWA-mediated increases in the tight junction proteins might depend on the Rac1 pathway. Furthermore, CWA improved the microbiota and short-chain fatty acid concentrations in the cecum of EHEC-infected mice. Although Enro and CWA had similar effects on intestinal inflammation, CWA was superior to Enro with regard to improving intestinal epithelial barrier and microbiota in the intestine. In conclusion, CWA attenuated EHEC-induced inflammation, intestinal epithelial barrier damage, and microbiota disruption in the intestine of mice, suggesting that CWA may be an effective therapy for many intestinal diseases.