CD14 Plays a Protective Role in Experimental Inflammatory Bowel Disease by Enhancing Intestinal Barrier Function

Causal role of immune cells in inflammatory bowel disease: A Mendelian randomization study

Inflammatory bowel disease (IBD) is characterized by an inflammatory response closely related to the immune system, but the relationship between inflammation and IBD remains unclear. We performed a comprehensive 2-sample Mendelian randomization (MR) analysis to determine the causal relationship between immune cell characteristics and IBD. Using publicly available genetic data, we explored the relationship between 731 immune cell characteristics and IBD risk. Inverse-variance weighting was the primary analytical method. To test the robustness of the results, we used the weighted median-based, MR-Egger, simple mode, and mode-based methods. Finally, we performed a reverse MR analysis to assess the possibility of reverse causality. We identified suggestive associations between 2 immune cell traits and IBD risk (P = 4.18 × 10-5 for human leukocyte antigen-DR on CD14+ monocytes, OR: 0.902; 95% CI: 0.859-0.947; for CD39+ CD4+ T cells, P = 6.24 × 10-5; OR: 1.042; 95% CI: 1.021-1.063). Sensitivity analysis results of these immune cell traits were consistent. In reverse MR analysis, we found no statistically significant association between IBD and these 2 cell traits. Our study demonstrates the close connection between immune cells and IBD using MR, providing guidance for future clinical and basic research.

Flow cytometry in the detection of circulating tumor cells in neoplastic effusions

PURPOSE

Despite its limitations, the cytology of body fluids is widely used in diagnosing neoplastic cells. Flow cytometry detects and identifies individual cells, enabling the detection of circulating tumor cells and facilitating diagnosis. This study compared the diagnostic utility of flow cytometry and cytology for detecting cancer cells in peritoneal and pleural fluids.

METHODOLOGY

We used flow cytometry and cytology to examine 119 pleural and peritoneal effusions received for routine screening. Antibodies against clusters of differentiation 45 (CD45), 14 (CD14), and Epithelial cell adhesion molecule (EpCAM) were used to detect malignant cells. Based on combined clinical and diagnostic information, 37 fluid specimens were malignant, and 77 were benign.

RESULTS

Flow cytometry correctly identified 34 cancers, while cytology identified 26 cancers (sensitivity 91.89 % vs. 70.27, respectively). Both methods had equal specificity (98.7 %). At a cut-off of > 0.29 % EpCAM(+) cells to all cells in the samples, flow cytometry accurately detected cancer cells, achieving 89.2 % sensitivity, 90.9 % specificity, and an AUC of 0.959 (p < 0.001).

CONCLUSION

Flow cytometry improves the detection of epithelial cancer cells in peritoneal and pleural fluids compared to conventional cytology. Due to similar specificity and higher sensitivity, flow cytometry offers a promising alternative to cytology for patient screening.

Transplant of microbiota from Crohn's disease patients to germ-free mice results in colitis

Although the role of the intestinal microbiota in the pathogenesis of inflammatory bowel disease (IBD) is beyond debate, attempts to verify the causative role of IBD-associated dysbiosis have been limited to reports of promoting the disease in genetically susceptible mice or in chemically induced colitis. We aimed to further test the host response to fecal microbiome transplantation (FMT) from Crohn's disease patients on mucosal homeostasis in ex-germ-free (xGF) mice. We characterized and transferred fecal microbiota from healthy patients and patients with defined Crohn's ileocolitis (CD_L3) to germ-free mice and analyzed the resulting microbial and mucosal homeostasis by 16S profiling, shotgun metagenomics, histology, immunofluorescence (IF) and RNAseq analysis. We observed a markedly reduced engraftment of CD_L3 microbiome compared to healthy control microbiota. FMT from CD_L3 patients did not lead to ileitis but resulted in colitis with features consistent with CD: a discontinued pattern of colitis, more proximal colonic localization, enlarged isolated lymphoid follicles and/or tertiary lymphoid organ neogenesis, and a transcriptomic pattern consistent with epithelial reprograming and promotion of the Paneth cell-like signature in the proximal colon and immune dysregulation characteristic of CD. The observed inflammatory response was associated with persistently increased abundance of Ruminococcus gnavus, Erysipelatoclostridium ramosum, Faecalimonas umbilicate, Blautia hominis, Clostridium butyricum, and C. paraputrificum and unexpected growth of toxigenic C. difficile, which was below the detection level in the community used for inoculation. Our study provides the first evidence that the transfer of a dysbiotic community from CD patients can lead to spontaneous inflammatory changes in the colon of xGF mice and identifies a signature microbial community capable of promoting colonization of pathogenic and conditionally pathogenic bacteria.

Multifaceted role of CD14 in innate immunity and tissue homeostasis

CD14 is a co-receptor of Toll-like receptor (TLR)- 4, with a critical role in innate immune responses. CD14 recognizes bacterial lipopolysaccharides, pathogen-, and damage-associated molecular patterns, thereby facilitating inflammatory immune responses. In addition to its well-established association with TLR4, CD14 is also implicated in TLR4-independent signaling, which leads to the apoptotic death of differentiated dendritic cells and activation of the noncanonical inflammasome pathway. CD14 also has a role beyond that of the immune responses. It contributes to tissue homeostasis by promoting the clearance of various apoptotic cells via recognizing externalized phosphatidylinositol phosphates. CD14 also has context-dependent roles, particularly in barrier tissues that include the skin and gastrointestinal tract. For example, CD14+ dendritic cells in the skin can induce immunostimulatory or immunosuppressive responses. In the gastrointestinal system, CD14 is involved in producing inflammatory cytokines in inflammatory bowel disease and maintaining of intestinal integrity. This review focuses on the multifaceted roles of CD14 in innate immunity and its potential regulatory functions in barrier tissues characterized by rapid cell renewal. By providing insights into the diverse functions of CD14, this review offers potential therapeutic implications for this versatile molecule in immune modulation and tissue homeostasis.

Cross talk between bacterial and human gene networks enriched using ncRNAs in IBD disease

Inflammatory bowel disease (IBD) is a long-term inflammatory immune-mediated gut illness with several extra-intestinal complications. The aims of this study were to identify a novel network-based meta-analysis approach on the basis of the combinations of the differentially expressed genes (DEGs) from microarray data, to enrich the functional modules from human protein-protein interaction (PPI) and gene ontology (GO) data, and to profile the ncRNAs on the genes involved in IBD. The gene expression profiles of GSE126124, GSE87473, GSE75214, and GSE95095 are obtained from the Gene Expression Omnibus (GEO) database based on the study criteria between 2017 and 2022. The DEGs were screened by the R software. DEGs were then used to examine gene ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The ncRNAs including the miRNAs and ceRNAs were predicted on the PPIs visualized using Cytoscape. Enrichment analysis of genes with differential expression (n = 342) using KEGG and GO showed that the signaling pathways related with staphylococcus aureus and pertussis bacterial infections may stimulate the immune system and exacerbate IBD via the interaction with human proteins including Fibrinogen gamma chain (FGG), Keratin 10 (KRT10), and Toll like receptor 4 (TLR4). By building a ceRNA network, lncRNA XIST and NEAT1 were determined by affecting common miRNAs, hsa-miR-6875-5p, hsa-miR-1908-5p, hsa-miR-186-5p, hsa-miR-6763-5p, hsa-miR-4436a, and hsa-miR-520a-5p. Additionally, the chromosome regions including NM_001039703 and NM_006267, which produce the most potent circRNAs play a significant role in the ceRNA network of IBD. Also, we predicted the siRNAs that would be most effective against the bacterial genes in staphylococcus aureus and pertussis infections. These findings suggested that three genes (FGG, KRT10, and TLR4), six miRNAs (hsa-miR-6875-5p, hsa-miR-1908-5p, hsa-miR-186-5p, hsa-miR-4436a, hsa-miR-520a-5p, and hsa-miR-6763-5p), two lncRNAs (XIST and NEAT1), and chromosomal regions including NM_001039703 and NM_006267 with the production of the most effective circRNAs are involved in the ncRNA-associated ceRNA network of IBD. These ncRNA profiles are related to the described gene functions and may play therapeutic targets in controlling inflammatory bowel disease.

Development of a newly immunoassay specific for mouse presepsin (sCD14-ST)

Presepsin (sCD14-ST) is used as a marker for sepsis diagnosis. The production mechanism of presepsin is unique in that it is produced through phagocytosis of microorganisms. However, some studies have demonstrated that non-infected patients had increased presepsin levels and that presepsin is related to the risk or severity of diseases. This study was designed to describe a sensitive sandwich enzyme-linked immunosorbent assay for mouse presepsin developed to investigate the association of presepsin with diseases. Polyclonal antibodies were generated from peptide-immunized rabbit antiserum. Mouse presepsin standard was prepared using the recombinant method as an Fc-fusion protein. The linear detection range of the method was 4.7-300 pg/mL with a detection limit of 1.4 pg/mL. The assay detected mouse presepsin where mouse soluble CD14 (sCD14) was digested by cathepsin D proteinase and the cross-reactivity of sCD14 was not observed. The normal levels of mouse presepsin and sCD14 were compared; 65.9 ± 21.4 pg/mL and 43.2 ± 7.2 ng/mL were determined, respectively. Moreover, the levels of presepsin and sCD14 were compared with a lipopolysaccharide (LPS)-injected sepsis mouse model. The newly developed analytical method had high specificity to presepsin and is an efficient tool for studying the association between presepsin and diseases.

CD14 signaling mediates lung immunopathology and mice mortality induced by Achromobacter xylosoxidans

Objective and design

Our research aimed to investigate the role of CD14 in pulmonary infection by Achromobacter xylosoxidans in an experimental murine model.

Methods

C57Bl/6 or CD14-deficient mice were infected intratracheally with non-lethal inoculum of A. xylosoxidans. At times 1, 3 and 7 days after infection, lungs, bronchoalveolar lavage and blood were collected. CD14 gene expression was determined by RT-PCR. The bacterial load in the lungs was assessed by counting colony forming units (CFU). Cytokines, chemokines, lipocalin-2 and sCD14 were quantified by the ELISA method. Inflammatory infiltrate was observed on histological sections stained with HE, and leukocyte subtypes were assessed by flow cytometry. In another set of experiments, C57Bl/6 or CD14-deficient mice were inoculated with lethal inoculum and the survival rate determined.

Results

CD14-deficient mice are protected from A. xylosoxidans-induced death, which is unrelated to bacterial load. The lungs of CD14-deficient mice presented a smaller area of tissue damage, less neutrophil and macrophage infiltration, less pulmonary edema, and a lower concentration of IL-6, TNF-α, CXCL1, CCL2 and CCL3 when compared with lungs of C57Bl/6 mice. We also observed that A. xylosoxidans infection increases the number of leukocytes expressing mCD14 and the levels of sCD14 in BALF and serum of C57Bl/6-infected mice.

Conclusions

In summary, our data show that in A. xylosoxidans infection, the activation of CD14 induces intense pulmonary inflammatory response resulting in mice death.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00011-022-01641-8.

Caspase-4 and -5 Biology in the Pathogenesis of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic relapsing inflammatory disease of the gastrointestinal tract, associated with high levels of inflammatory cytokine production. Human caspases-4 and -5, and their murine ortholog caspase-11, are essential components of the innate immune pathway, capable of sensing and responding to intracellular lipopolysaccharide (LPS), a component of Gram-negative bacteria. Following their activation by LPS, these caspases initiate potent inflammation by causing pyroptosis, a lytic form of cell death. While this pathway is essential for host defence against bacterial infection, it is also negatively associated with inflammatory pathologies. Caspases-4/-5/-11 display increased intestinal expression during IBD and have been implicated in chronic IBD inflammation. This review discusses the current literature in this area, identifying links between inflammatory caspase activity and IBD in both human and murine models. Differences in the expression and functions of caspases-4, -5 and -11 are discussed, in addition to mechanisms of their activation, function and regulation, and how these mechanisms may contribute to the pathogenesis of IBD.

Intestinal helminth infection transforms the CD4+ T cell composition of the skin

Intestinal helminth parasites can alter immune responses to vaccines, other infections, allergens and autoantigens, implying effects on host immune responses in distal barrier tissues. We herein show that the skin of C57BL/6 mice infected with the strictly intestinal nematode Heligmosomoides polygyrus contain higher numbers of CD4⁺ T cells compared to the skin of uninfected controls. Accumulated CD4⁺ T cells were H. polygyrus-specific T_H2 cells that skewed the skin CD4⁺ T cell composition towards a higher T_H2/T_H1 ratio which persisted after worm expulsion. Accumulation of T_H2 cells in the skin was associated with increased expression of the skin-homing chemokine receptors CCR4 and CCR10 on CD4⁺ T cells in the blood and mesenteric lymph nodes draining the infected intestine and was abolished by FTY720 treatment during infection, indicating gut-to-skin trafficking of cells. Remarkably, skin T_H2 accumulation was associated with impaired capacity to initiate IFN-γ recall responses and develop skin-resident memory cells to mycobacterial antigens, both during infection and months after deworming therapy. In conclusion, we show that infection by a strictly intestinal helminth has long-term effects on immune cell composition and local immune responses to unrelated antigens in the skin, revealing a novel process for T cell colonisation and worm-mediated immunosuppression in this organ.

Pharmacogenetics of Biological Agents Used in Inflammatory Bowel Disease: A Systematic Review

Inflammatory Bowel Disease (IBD) comprises a group of disorders, in particular Crohn's disease (CD) and ulcerative colitis (UC), characterized by chronic inflammation affecting the gastrointestinal tract. The treatment of these conditions is primarily based on anti-inflammatory drugs, although the use of biological drugs with lower side effects quickly increased in the last decade. However, the presence of certain polymorphisms in the population may determine a different outcome in response to therapy, reflecting the heterogeneity of the efficacy in patients. Considering that several studies showed important correlations between genetic polymorphisms and response to biological treatments in IBD patients, this systematic review aims to summarize the pharmacogenetics of biologicals approved for IBD, thus highlighting a possible association between some polymorphisms and drug response. With this purpose, we reviewed PubMed papers published over the past 21 years (2000-2021), using as the search term "drug name and IBD or CD or UC and polymorphisms" to underline the role of pharmacogenetic tests in approaching the disease with a targeted therapy.

The Role of β-Carotene in Colonic Inflammation and Intestinal Barrier Integrity

Background: Carotenoids are naturally occurring pigments accounting for the brilliant colors of fruits and vegetables. They may display antioxidant and anti-inflammatory properties in humans besides being precursors to vitamin A. There is a gap of knowledge in examining their role within colonic epithelial cells. We proposed to address this research gap by examining the effects of a major dietary carotenoid, β-carotene, in the in vitro epithelial cell model. Methods: We examined the function of β-carotene in the lipopolysaccharide (LPS)/toll-like receptor 4 (TLR4) signaling pathway. We conducted western blotting assays to evaluate expressions of TLR4 and its co-receptor, CD14. We also examined NF-κB p65 subunit protein levels in the model system. Furthermore, we studied the impact of β-carotene on the tight junction proteins, claudin-1, and occludin. We further carried out immunocytochemistry experiments to detect and visualize claudin-1 expression. Results: β-Carotene reduced LPS-induced intestinal inflammation in colonic epithelial cells. β-Carotene also promoted the levels of tight junction proteins, which might lead to enhanced barrier function. Conclusions: β-Carotene could play a role in modulating the LPS-induced TLR4 signaling pathway and in enhancing tight junction proteins. The findings will shed light on the role of β-carotene in colonic inflammation and also potentially in metabolic disorders since higher levels of LPS might induce features of metabolic diseases.

Systemic Proteomic Analysis Reveals Distinct Exosomal Protein Profiles in Rheumatoid Arthritis

Objective

Rheumatoid arthritis (RA) is a complex disease with unknown pathogenesis. In recent years, fewer have paid attention to the broad spectrum of systemic markers of RA. The aim of this study was to identify exosomal candidate proteins in the pathogenesis of RA.

Methods

Totally, 12 specimens of plasma from 6 RA patients and 6 age- and gender-matched controls from the Chinese population were obtained for nanoscale liquid chromatography coupled to tandem mass spectrometry (nano-LC-MS/MS) analysis to identify exosomal profiles.

Results

A total of 278 exosomal proteins were detected. Among them, 32 proteins were significantly upregulated (FC ≥ 2.0 and P < 0.05) and 5 proteins were downregulated (FC ≤ 0.5 and P < 0.05). Bioinformatics analysis revealed that transthyretin (TTR), angiotensinogen (AGT), lipopolysaccharide-binding protein (LBP), monocyte differentiation antigen CD14 (CD14), cartilage oligomeric matrix protein (COMP), serum amyloid P (SAP/APCS), and tenascin (TNC) can interact with each other. Subsequently, these cross-linked proteins may be mainly involved in the inflammatory-related pathways to mediate the onset of RA. Noteworthy, the LBP/CD14 complex can promote the expression of IL-8 and TNF-α, eventually leading to the development of RA.

Conclusions

Our findings suggest distinct plasmatic exosomal protein profiles in RA patients. These proteins not only take important parts in the vicious circle in the pathogenic process of RA but also serve as novel biomarkers in RA diagnosis and prognosis.

Synergistic effect of combined treatment with baicalin and emodin on DSS-induced colitis in mouse

The treatment of combination drugs in complex diseases has been spotlighted. Ulcerative colitis (UC) is a chronic inflammatory disease that has made progress in combination therapy. Baicalin, a flavone from Scutellaria baicalensis Georgi. (Lamiaceae), and emodin, an anthraquinone derivative from Rhei Radix et Rhizoma. (Polygonaceae), both have been reported to possess antiinflammatory activities. Our study investigated whether combined treatment with baicalin and emodin had a synergistic effect in inhibiting colitis inflammation. The results showed that baicalin combined with emodin at a lower dose had the same effect as the two drugs alone significantly alleviated the symptoms of dextran sulfate sodium (DSS)-induced colitis mice, involving the prevention of the loss of body weight and colon shortening, the decrease in the disease activity index (DAI), and intestinal damages. The combined treatment decreased the expression of CD14/TLR4/NF-κB pathway proteins and increased the expression of PPAR-γ protein in the colon of colitis mice. Further study in vitro has shown that baicalin decreased the expression of CD14, whereas emodin increased the expression of PPAR-γ, both of which inhibited the activity of NF-κB and exerted antiinflammatory effects. Furthermore, compared to the treatment using the two drugs individually, baicalin combined with emodin had more significant effects on the expression of CD14 and PPAR-γ. Therefore, emodin combined with baicalin had a synergistic effect on DSS-induced colitis.

Fabrication and Evaluation of Celecoxib Oral Oleogel to Reduce the Inflammation of Ulcerative Colitis

Oleogel consists of hydrophobic solvent and an oleogelator. In this study, attempts were made to study the influence of Celecoxib solubility, concentration and dispersability on its release, absorption, and biological performance. Oleogels were prepared to study the formulation variables on its stability and release. Castor oil was selected as the oil and the oleogelator concentration was 4.5% w/w. F3 revealed the highest release and stability compared to other formulae. The percent permeated across the rat intestine showed a 7.5-fold increase over free Celecoxib, and its lifetime was found to be greater than 18 months. The efficacy of free Celecoxib and oleogel formulae to treat rats with ulcerative colitis was done via the induction of ulcerative colitis (UC) through administration of 5% dextran sodium sulphate (DSS). Celecoxib besides its formulae significantly reduced the release of Leucine rich 2 glycoprotein (LRG), Myeloperoxidase (MPO), Tumor necrosis factor-α (TNF-α), proinflammatory cytokine expression, High mobility group box 1 (HMGB1), Nuclear factor kappa B (NF-ΚB), Trefoil Factor 3 (TFF3), Metalloproteinase-3 (MMP3), and miRNA31. Moreover, F3 significantly increased the colonic cAMP in DSS treated rats and reduced the intestinal inflammation beside healing of mucosa and restitution of the epithelium of the gastrointestinal tract.

The Role of Gut Barrier Dysfunction and Microbiome Dysbiosis in Colorectal Cancer Development

Accumulating evidence indicates that breakdown of the+ protective mucosal barrier of the gut plays a role in colorectal cancer (CRC) development. Inflammation and oxidative stress in the colonic epithelium are thought to be involved in colorectal carcinogenesis and the breakdown of the integrity of the colonic barrier may increase the exposure of colonocytes to toxins from the colonic milieu, enhancing inflammatory processes and release of Reactive Oxygen Species (ROS). The aetiological importance of the gut microbiome and its composition - influenced by consumption of processed meats, red meats and alcoholic drinks, smoking, physical inactivity, obesity - in CRC development is also increasingly being recognized. The gut microbiome has diverse roles, such as in nutrient metabolism and immune modulation. However, microbial encroachment towards the colonic epithelium may promote inflammation and oxidative stress and even translocation of species across the colonic lumen. Recent research suggests that factors that modify the above mechanisms, e.g., obesity and Western diet, also alter gut microbiota, degrade the integrity of the gut protective barrier, and expose colonocytes to toxins. However, it remains unclear how obesity, lifestyle and metabolic factors contribute to gut-barrier integrity, leading to metabolic disturbance, colonocyte damage, and potentially to CRC development. This review will discuss the interactive roles of gut-barrier dysfunction, microbiome dysbiosis, and exposure to endogenous toxins as another mechanism in CRC development, and how biomarkers of colonic mucosal barrier function may provide avenues for disease, prevention and detection.

Baicalin prevents LPS-induced activation of TLR4/NF-κB p65 pathway and inflammation in mice via inhibiting the expression of CD14

Previous studies have shown that baicalin, an active ingredient of the Chinese traditional medicine Huangqin, attenuates LPS-induced inflammation by inhibiting the activation of TLR4/NF-κBp65 pathway, but how it affects this pathway is unknown. It has been shown that CD14 binds directly to LPS and plays an important role in sensitizing the cells to minute quantities of LPS via chaperoning LPS molecules to the TLR4/MD-2 signaling complex. In the present study we investigated the role of CD14 in the anti-inflammatory effects of baicalin in vitro and in vivo. Exposure to LPS (1 μg/mL) induced inflammatory responses in RAW264.7 cells, evidenced by marked increases in the expression of MHC II molecules and the secretion of NO and IL-6, and by activation of MyD88/NF-κB p65 signaling pathway, as well as the expression of CD14 and TLR4. These changes were dose-dependently attenuated by pretreatment baicalin (12.5-50 μM), but not by baicalin post-treatment. In RAW264.7 cells without LPS stimulation, baicalin dose-dependently inhibit the protein and mRNA expression of CD14, but not TLR4. In RAW264.7 cells with CD14 knockdown, baicalin pretreatment did not prevent inflammatory responses and activation of MyD88/NF-κB p65 pathway induced by high concentrations (1000 μg/mL) of LPS. Furthermore, baicalin pretreatment also inhibited the expression of CD14 and activation of MyD88/NF-κB p65 pathway in LPS-induced hepatocyte-derived HepG2 cells and intestinal epithelial-derived HT-29 cells. In mice with intraperitoneal injection of LPS and in DSS-induced UC mice, oral administration of baicalin exerted protective effects by inhibition of CD14 expression and inflammation. Taken together, we demonstrate that baicalin pretreatment prevents LPS-induced inflammation in RAW264.7 cells in CD14-dependent manner. This study supports the therapeutic use of baicalin in preventing the progression of LPS-induced inflammatory diseases.

Examination of intestinal ultrastructure, bowel wall apoptosis and tight junctions in the early phase of sepsis

Gut hyperpermeability can be caused by either apoptosis of the intestinal epithelium or altered status, permeability or porosity of tight junctions. This project aims to elucidate these mechanisms in the early phase of sepsis. Eighteen male wild type mice were randomized to two groups. All mice received one single gavage of fluorescein isothiocyanate (FITC) dextran 30 min before intervention. One group (n = 10) underwent cecal ligation and puncture to induce sepsis. The other group (n = 8) was sham operated. Septic animals exhibited significantly increased permeability for FITC 8 h post-operatively. Significantly increased serum interleukin-6, tumor-necrosis-factor-alpha and interleukin-1-beta confirmed sepsis. Septic animals showed significant bowel wall inflammation of ileum and colon samples. PCR revealed significantly increased expression of claudin-2 and decreased expressions of claudin-4, tight-junction-protein-1 and occludin-1 resembling increased permeability of tight junctions. However, these alterations could not be confirmed at the protein level. Light microscopy revealed significant dilatation of intercellular spaces at the basal sections of intestinal epithelial cells (IEC) in septic animals confirmed by increased intercellular spaces at the level of tight junctions and adherens junctions in electron microscopy (TEM). In small angle X-ray scattering no increase in number or size of nanopores could be shown in the bowel wall. HOECHST staining and PCR of ileum samples for apoptosis markers proofed no relevant differences in intestinal epithelial cell apoptosis between the groups. Intestinal hyperpermeability in septic animals was most likely caused by alterations of the intercellular contacts and not by apoptosis or increased size/number of nanopores of intestinal epithelial cells in this murine model of early sepsis.

MicroRNA-674-5p induced by HIF-1α targets XBP-1 in intestinal epithelial cell injury during endotoxemia

Intestinal mucosal integrity dysfunction during endotoxemia can contribute to translocation of intestinal bacteria and a persistent systemic inflammatory response, which both fuel the pathophysiological development of sepsis or endotoxemia. The pathogenesis of intestinal damage induced by endotoxemia remains poorly understood. Here, we identified the microRNA (miR)-674-5p/X-box binding protein 1 (XBP-1) axis as a critical regulator and therapeutic target in preventing intestinal crypt cell proliferation during endotoxemia. MiR-674-5p was markedly increased in intestinal epithelial cells (IECs) during endotoxemia and its induction depended on hypoxia-inducible factor-1α (HIF-1α). Intriguingly, gene expression microanalysis revealed that expression of XBP-1 was down-regulated in IECs with over-expression of miR-674-5p. miR-674-5p was found to directly target XBP-1 protein expression. Upon in vitro, anti-miR-674-5p enhanced sXBP-1 expression and facilitated intestinal crypt cell proliferation. Blockade of miR-674-5p promoted XBP-1 activity, attenuated intestinal inflammation, and expedited intestinal regeneration, resulting in protection against endotoxemia-induced intestinal injury in mice. More importantly, the survival in endotoxemia mice was significantly improved by inhibiting intestinal miR-674-5p. Collectively, these data indicate that control of a novel miR-674-5p/XBP-1 signaling axis may mitigate endotoxemia -induced intestinal injury.

Tight junctions in the development of asthma, chronic rhinosinusitis, atopic dermatitis, eosinophilic esophagitis, and inflammatory bowel diseases

This review focuses on recent developments related to asthma, chronic rhinosinusitis, atopic dermatitis (AD), eosinophilic esophagitis, and inflammatory bowel diseases (IBD), with a particular focus on tight junctions (TJs) and their role in the pathogenetic mechanisms of these diseases. Lung, skin, and intestinal surfaces are lined by epithelial cells that interact with environmental factors and immune cells. Therefore, together with the cellular immune system, the epithelium performs a pivotal role as the first line physical barrier against external antigens. Paracellular space is almost exclusively sealed by TJs and is maintained by complex protein-protein interactions. Thus, TJ dysfunction increases paracellular permeability, resulting in enhanced flux across TJs. Epithelial TJ dysfunction also causes immune cell activation and contributes to the pathogenesis of chronic lung, skin, and intestinal inflammation. Characterization of TJ protein alteration is one of the key factors for enhancing our understanding of allergic diseases as well as IBDs. Furthermore, TJ-based epithelial disturbance can promote immune cell behaviors, such as those in dendritic cells, Th2 cells, Th17 cells, and innate lymphoid cells (ILCs), thereby offering new insights into TJ-based targets. The purpose of this review is to illustrate how TJ dysfunction can lead to the disruption of the immune homeostasis in barrier tissues and subsequent inflammation. This review also highlights the various TJ barrier dysfunctions across different organ sites, which would help to develop future drugs to target allergic diseases and IBD.

CD14 and ALPK1 Affect Expression of Tight Junction Components and Proinflammatory Mediators upon Bacterial Stimulation in a Colonic 3D Organoid Model

Cd14 and Alpk1 both encode pathogen recognition receptors and are known candidate genes for affecting severity in inflammatory bowel diseases. CD14 acts as a coreceptor for bacterial lipopolysaccharide (LPS), while ALPK1 senses ADP-D-glycero-beta-D-manno-heptose, a metabolic intermediate of LPS biosynthesis. Intestinal barrier integrity can be influenced by CD14, whereas to date, the role of ALPK1 in maintaining barrier function remains unknown. We used colon-derived 3D organoids, first characterised for growth, proliferation, stem cell markers, and expression of tight junction (TJ) components using qPCR and immunohistochemistry. They showed characteristic crypt stem cells, apical shedding of dead cells, and TJ formation. Afterwards, organoids of different genotypes (WT, Il10^−/−, Cd14^−/−, and Alpk1^−/−) were then stimulated with either LPS or Escherichia coli Nissle 1917 (EcN). Gene expression and protein levels of cytokines and TJ components were analysed. WT organoids increased expression of Tnfα and tight junction components. Cd14^−/− organoids expressed significantly less Tnfα and Ocln after LPS stimulation than WT organoids but reacted similarly to WT organoids after EcN stimulation. In contrast, compared to WT, Alpk1^−/− organoids showed decreased expression of different TJ and cytokine genes in response to EcN but not LPS. However, Western blotting revealed an effect of ALPK1 on TJ protein levels. These findings demonstrate that Cd14, but not Alpk1, alters the response to LPS stimulation in colonic epithelial cells, whereas Alpk1 is involved in the response upon bacterial challenge.

Protective effect of Saccharomyces boulardii on intestinal mucosal barrier of dextran sodium sulfate-induced colitis in mice

Background:

The effect and mechanism of Saccharomyces boulardii (Sb) in inflammatory bowel disease are unclear. The objective of the study was to evaluate the impact of Sb on intestinal mucosal barrier and intestinal flora in a colitis mouse model.

Methods:

Forty C57BL/6J male mice were randomly assigned to five groups: normal control group (A), pathologic control group (B), Sb treatment group (C), mesalazine treatment group (D), and Sb combined with mesalazine treatment group (E). Colitis was induced by the addition of 2.5% (wt/vol) dextran sodium sulfate (DSS) in the drinking water ad libitum for 7 days. The general condition, weight change, stool property, and bloody stool level of mice were observed to evaluate the disease activity index. The expression of zona occludens-1 (ZO-1) and occludin in intestinal tissue were measured by immunohistochemistry. The level of tumor necrosis factor-α (TNF-α) and interleukin (IL)-8 in plasma was measured by enzyme linked immunosorbent assay. Inter-cellular tight junctions were observed by transmission electron microscopy. The feces and intestinal contents were collected sterilely, and intestinal flora was analyzed by 16S rRNA sequencing.

Results:

Compared with group B, Sb reduced the disease activity index and histological score of group C (disease activity index: group B 2.708 ± 0.628, group C 1.542 ± 0.616, P_BC = 0.005; histological score: group B 9.875 ± 3.271, group C 4.750 ± 1.832, P_BC = 0.005) in DSS-induced colitis in mice. Sb exerted a protect effect on the expression of ZO-1 (group B 2.075 ± 1.176, group C 4.225 ± 1.316, P_BC = 0.019) and occludin (group B 2.200 ± 0.968, group C 3.525 ± 1.047, P_BC = 0.023). Compared with group B, Sb decreased the level of TNF-α and IL-8 of group C (TNF-α: group B 716.323 ± 44.691 ng/L, group C 521.740 ± 90.121 ng/L, P_BC = 0.001; IL-8: group B 128.992 ± 11.475 pg/mL, group C 106.283 ± 15.906 pg/mL, P_BC = 0.012). Treatment with Sb preserved the tight junctions and ameliorated microvilli and inter-cellular space. Treatment with Sb also showed its own characteristics: a higher percentage of Bacteroidetes and a lower percentage of Firmicutes, with significant differences or a significant trend. The proportion of the S24-7 family was increased significantly in the Sb treatment group.

Conclusions:

Sb shows an anti-inflammatory effect and has a protective effect on the intestinal mucosal mechanical barrier. Sb may up-regulate the abundance of family S24-7 specifically, and maybe a mechanism underlying its function.

Protective effects of oxymatrine against DSS-induced acute intestinal inflammation in mice via blocking the RhoA/ROCK signaling pathway

Oxymatrine (OMT) is an important quinoxaline alkaloid that has a wide range of pharmacological effects and has been shown to alleviate ulcerative colitis due to its profound anti-inflammatory effects. The RhoA/ROCK (Rho kinase) signaling pathway has been shown to be related to the pathogenesis of several autoimmune diseases; however, the specific mechanisms of RhoA/ROCK signaling in inflammatory bowel disease (IBD) remain elusive. Therefore, we sought to determine whether OMT could ameliorate acute intestinal inflammation by targeting the RhoA/ROCK signaling pathway. The potential therapeutic effect of OMT on acute intestinal inflammation and its impact on the RhoA/ROCK signaling pathway were assessed in six groups of mice treated with low, medium and high doses of OMT (25, 50 and 100 mg/kg, respectively), and an inhibitor of ROCK, Y-27632, as a positive control, after initiating dextran sodium sulfate (DSS)-induced acute intestinal inflammation. The model group and normal group were injected intraperitoneally with equal doses of PBS. Our results showed that OMT treatment could protect the integrity of the epithelial barrier, relieve oxidative stress, inhibit the expression of inflammatory mediators and pro-inflammatory cytokines, restrain the differentiation of Th17 cells and promote the differentiation of Treg cells via inhibition of the RhoA/ROCK pathway, thus providing therapeutic benefits for ulcerative colitis (UC). Therefore, inhibiting the RhoA/ROCK pathway might be a new approach that can be used in UC therapy, which deserves to be investigated further.

CD14: Biology and role in the pathogenesis of disease

Human monocyte differentiation antigen CD14 is a pattern recognition receptor (PRR) that enhances innate immune responses. CD14 was first identified as a marker of monocytes to signal intracellular responses upon bacterial encounters. Given the absence of an intracellular tail, CD14 was doubted to have the signaling capacities. Later CD14 was confirmed as the TLR co-receptor for the detection of pathogen-associated molecular patterns. However, CD14 has been revealed as a multi-talented receptor. In last decade, CD14 was identified to activate NFAT to regulate the life cycle of myeloid cells in a TLR4-independent manner and to transport inflammatory lipids to induce phagocyte hyperactivation. And its influences on multiple related diseases have been further considered. In this review, we summarize advancements in the basic biology of the CD14 including its structure, binding ligands, signaling pathways, and its roles in the pathogenesis of inflammation, atherosclerosis, tumor and metabolic diseases. We also discuss the therapeutic potential of targeting the CD14 in related diseases.

Effects and Mechanism of Constitutive TL1A Expression on Intestinal Mucosal Barrier in DSS-Induced Colitis

OBJECTIVE

The role of TL1A in the intestinal mucosa barrier in inflammatory bowel disease (IBD) is still unclear. This study was aimed to investigate the expression levels of tight junction protein (TJ), myosin light chain kinase (MLCK), MyD88 and tumor necrosis factor (TNF) receptor-associated factor-6 (TRAF6) and how TL1A influences the intestinal barrier in IBD.

METHODS

The mouse models of IBD were built using FMS-TL1A-GFP-transgenic mice and wild-type mice. The morphological and histopathological changes, bacterial translocation, permeability of colonic mucosa, and LPS level were assessed. Caco-2 cells were used to further investigate the association between TL1A and TNF-α and LPS. The protein level and mRNA changes of TJ proteins including ZO-1, occluding, JAMA, claudin-1, claudin-2, and claudin-3 were investigated using Western blot and real-time PCR. Protein changes of MLCK, MyD88 and TNF receptor-associated factor-6 (TRAF6), and TNF-α mRNA in the mouse colon were further assessed.

RESULTS

The IBD models were successfully built. Cooper HS score and histopathological score of the colon were higher in DSS/WT group than in control/WT group (P < 0.05), higher in DSS/Tg group than in control/Tg group (P < 0.05), and higher in DSS/Tg group than in DSS/WT group. PAS, colonic permeability of the colon, and FITC-D examination showed the similar results and trends. Compared with control/WT group, the levels of TL1A and claudin-2 were higher and the levels of ZO-1, occludin, JAMA, claudin-1, and claudin-3 were lower in DSS/WT group (P < 0.05). Compared with control/Tg group, the levels of TL1A and claudin-2 were higher and the levels of ZO-1, occludin, JAMA, claudin-1, and claudin-3 were lower in DSS/Tg group. Compared with Caco-2 + TNF-α group, the expression level of occludin and claudin-1 in Caco-2 + LV-TNFSF15 + TNF-α group was significantly lower (P < 0.05); p-MLC level was significantly higher. Compared with Caco-2 + LPS group, the expression level of occludin and claudin-1 significantly decreased in Caco-2 + LV-TNFSF15 + LPS group; MyD88 and TRAF6 expression level significantly increased.

CONCLUSION

The results suggested that TL1A could impair intestinal epithelial barrier in the mouse model of IBD and might regulate TJ expression via MLCK/p-MLC pathway and LPS-mediated MyD88/TRAF6 pathway.

Dietary Chitin Particles Called Mimetic Fungi Ameliorate Colitis in Toll-Like Receptor 2/CD14- and Sex-Dependent Manners

Chitin is a natural N-acetylglucosamine polymer and a major structural component of fungal cell walls. Dietary chitin is mucoadhesive; anti-inflammatory effects of chitin microparticles (CMPs; 1- to 10-μm diameters) have been demonstrated in models of inflammatory bowel disease (IBD). The goals of this study were to assess (i) whether CMPs among various chitin preparations are the most effective against colitis in male and female mice and (ii) whether host chitin-binding Toll-like receptor 2 (TLR2) and CD14 are required for the anti-inflammatory effect of chitin. We found that colitis in male mice was ameliorated by CMPs and large chitin beads (LCBs; 40 to 70 μm) but not by chitosan (deacetylated chitin) microparticles, oligosaccharide chitin, or glucosamine. In fact, LCBs were more effective than CMPs. In female colitis, on the other hand, CMPs and LCBs were equally and highly effective. Neither sex of TLR2-deficient mice showed anti-inflammatory effects when treated with LCBs. No anti-inflammatory effect of LCBs was seen in either CD14-deficient males or females. Furthermore, an in vitro study indicated that when LCBs and CMPs were digested with stomach acidic mammalian chitinase (AMC), their size-dependent macrophage activations were modified, at least in part, suggesting reduced particle sizes of dietary chitin in the stomach. Interestingly, stomach AMC activity was greater in males than females. Our results indicated that dietary LCBs were the most effective preparation for treating colitis in both sexes; these anti-inflammatory effects of LCBs were dependent on host TLR2 and CD14.

The effects of neuroblastoma and chemotherapy on metabolism, fecal microbiome, volatile organic compounds, and gut barrier function in a murine model

BACKGROUND

Following transplantation of human neuroblastoma (NB) cells into athymic mice, we investigated the effects of tumor growth and cyclophosphamide (CTX) treatment on systemic metabolism, gut inflammation and permeability, fecal microbiome and volatile organic compounds (VOCs).

METHODS

NB cells (MHH-NB11) were implanted into athymic mice (n=20); 20 healthy mice served as controls (sham).  CTX was given to 20 animals (10 NB and 10 sham) after 8 and 9 weeks. Metabolic changes were measured. Ileum samples were obtained for RT-PCR (claudins 2 and 4, occludin, tight junction protein 1) and apoptosis rate determination. Fecal microbiome and VOCs were analyzed. Values were compared to sham animals.

RESULTS

NB caused reduction of adipose tissue, increases of IL-6 and TNF-α, and decreases of TGF-β1 and -β2. Serum FITC-dextrane levels were increased in NB and improved under CTX. Claudin 4 expression was higher in NB versus NB + CTX and sham animals. NB caused increased apoptosis of epithelial cells. NB but also CTX led to a reduction in the abundance of Lactobacillus. NB led to alterations of the fecal VOC profile.

CONCLUSIONS

NB caused a catabolic pro-inflammatory state, increased gut permeability, altered fecal VOCs and reductions of Lactobacillus. Further investigations are required to determine if modifications of the intestinal microbiome may reverse some of the observed effects.

Cisplatin-Induced Rodent Model of Kidney Injury: Characteristics and Challenges

Cisplatin is an antitumor drug used in the treatment of a wide variety of malignancies. However, its primary dose-limiting side effect is kidney injury, which is a major clinical concern. To help understand mechanisms involved in the development of kidney injury, cisplatin rodent model has been developed. Given the complex pathogenesis of kidney injury, which involves both local events in the kidney and interconnected and interdependent systemic effects in the body, cisplatin rodent model is indispensable in the investigation of underlying mechanisms and potential treatment strategies of both acute and chronic kidney injury. Cisplatin rodent model is well appreciated and widely used model due to its simplicity. It has many similarities to human cisplatin nephrotoxicity, which are mentioned in the paper. In spite of its simplicity and wide applicability, there are also traps that need to be taken into account when using cisplatin model. The present paper is aimed at giving a concise insight into the complex characteristics of cisplatin rodent model and heterogeneity of cisplatin dosage regimens as well as outlining factors that can severely influence the outcome of the model and the study. Challenges for future research are also mentioned.

Loss of CD14 leads to disturbed epithelial-B cell crosstalk and impairment of the intestinal barrier after E. coli Nissle monoassociation

The TLR4 co-receptor CD14 was identified as an IBD candidate gene. Here, its influence on the intestinal barrier was addressed utilizing E. coli Nissle (EcN), which induces severe inflammation in germfree TLR4^-/- mice. After monoassociation, EcN was detected in spleens and livers of TLR4^-/- and CD14^-/- but not wildtype mice. Barrier impairment was characterized by increased apoptosis and decreased epithelial junction (EJ) expression and was reversed by TLR2 stimulation in CD14^-/- mice. Bone marrow (BM) transplantation revealed contribution of hematopoietic and non-hematopoietic cells towards intestinal homeostasis. EcN inoculated WT mice showed B cell activation, CD14^-/- and TLR4^-/- mice cytotoxic T cell and impaired B cell responses. The latter was characterized by absence of B cells in TLR4^-/- mice, decreased levels of EcN induced immunoglobulins and downregulation of their transporter pIgR. EcN colonization of mice with genetically or antibody induced impaired B cell response resulted in dissemination of EcN and downregulation of EJ. BM chimeras indicated that CD14 originating from radiation resistant cells is sufficient to restore EJ-function. Overall, CD14/TLR4 signalling seems to be critical for intestinal barrier function and for the crosstalk between B cells and the epithelium, underlining that CD14 serves as a protective modulator of intestinal homeostasis.

Comparative Evaluation between Sulfasalazine Alone and in Combination with Herbal Medicine on DSS-Induced Ulcerative Colitis Mice

The present study aimed to investigate the comparative evaluation of pharmacological efficacy between sulfasalazine alone and sulfasalazine in combination with herbal medicine on dextran sodium sulfate- (DSS-) induced UC in mice. Balb/c mice received 5% DSS in drinking water for 7 days to induce colitis. Animals were divided into five groups (n = 9): Group I (normal group), Group II (DSS control group), Group III (DSS + sulfasalazine (30 mg/kg)), Group IV (DSS + sulfasalazine (60 mg/kg)), and Group V (DSS + sulfasalazine (30 mg/kg) + Cinnamomi Cortex and Bupleuri Radix mixture (30 mg/kg) (SCB)). Colonic pathological changes were analyzed using hematoxyline/eosin staining. The antioxidant, inflammatory, and apoptotic protein levels were determined using western blotting. SCB supplementation, as well as sulfasalazine, suppressed colonic length and mucosal inflammatory infiltration. In addition, SCB treatment significantly reduced the expression of proinflammatory signaling molecules through suppression of both mitogen-activated protein kinases (MAPK) and nuclear factor-kappa B (NF-κB) signaling pathways and prevented the apoptosis of the colon. Moreover, SCB administration significantly led to the upregulation of antioxidant enzymes including SOD and catalase. Taken together, SCB treatment might offer a better treatment for human UC than sulfasalazine alone or may be useful as an alternative therapeutic strategy against UC, without any evidence of side effects.