TNFAIP3 maintains intestinal barrier function and supports epithelial cell tight junctions

Regulation of placental development and function by ubiquitination

The proper distribution of nutrients and metabolites between the mother and fetus is one important factor for successful pregnancy. As a bridge, the placenta plays a key role in sensing the nutritional needs of the fetus, coordinating the maternal nutrition supply, and enhancing its nutritional transport capabilities. Imperfect placental development can lead to pregnancy-related disorders such as preeclampsia, recurrent miscarriage, and/or fetal growth restriction, posing risks to both mother and child in the short and long term. However, current understanding of the human placenta remains as a "black box", and its developmental control mechanisms for adaptive pregnant regulation still needs to be elucidated. As one form of post-translational modification (PTM), ubiquitination plays an important role in regulating cellular functions and is regarded as a valuable drug target. Particularly, ubiquitination related to placenta development has been discovered in recent years. Placental development processes closely associated with pregnant complications, such as blastocyst implantation, syncytiotrophoblast cell differentiation, and immune barrier maintenance, have been reported to be affected by ubiquitination. However, the diagnosis and intervention of pregnancy diseases also urgently need to be improved. Thus, aiming to comprehensive summarize and further exploring the molecular mechanism, target and regulatory mechanism of pregnancy complications, we have herein reviewed genes and pathways regulating pregnancy progress and diseases and focusing on ubiquitin-related physiological process in placenta.

Genetic Mutations Associated With TNFAIP3 (A20) Haploinsufficiency and Their Impact on Inflammatory Diseases

TNF-α-induced protein 3 (TNFAIP3), commonly referred to as A20, is an integral part of the ubiquitin-editing complex that significantly influences immune regulation, apoptosis, and the initiation of diverse immune responses. The A20 protein is characterized by an N-terminal ovarian tumor (OTU) domain and a series of seven zinc finger (ZNF) domains. Mutations in the TNFAIP3 gene are implicated in various immune-related diseases, such as Behçet's disease, polyarticular juvenile idiopathic arthritis, autoimmune thyroiditis, autoimmune hepatitis, and rheumatoid arthritis. These mutations can lead to a spectrum of symptoms, including, but not limited to, recurrent fever, ulcers, rashes, musculoskeletal and gastrointestinal dysfunctions, cardiovascular issues, and respiratory infections. The majority of these mutations are either nonsense (STOP codon) or frameshift mutations, which are typically associated with immune dysfunctions. Nonetheless, missense mutations have also been identified as contributors to these conditions. These genetic alterations may interfere with several biological pathways, notably abnormal NF-κB signaling and dysregulated ubiquitination. Currently, there is no definitive treatment for A20 haploinsufficiency; however, therapeutic strategies can alleviate the symptoms in patients. This review delves into the mutations reported in the TNFAIP3 gene, the clinical progression in affected individuals, potential disease mechanisms, and a brief overview of the available pharmacological interventions for A20 haploinsufficiency. Mandatory genetic testing of the TNFAIP3 gene should be performed in patients diagnosed with autoinflammatory disorders to better understand the genetic underpinnings and guide treatment decisions.

Inflammatory Gene Panel Guiding the Study of Genetics in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a complex disease that develops through a sequence of molecular events that are still poorly defined. This process is driven by a multitude of context-dependent genes that play different roles based on their environment. The complexity and multi-faceted nature of these genes make it difficult to study the genetic basis of IBD. The goal of this article is to review the key genes in the pathophysiology of IBD and highlight new technology that can be used in further research. This paper examines Nanostring RNA probe technology, which uses tissue analyzed without the use of enzymes, transcription, or amplification. Nanostring offers several panels of genes to test, including an inflammation panel of 234 genes. This article analyzes this panel and reviews the literature for each gene's effect in IBD for use as a framework to review the pathophysiology of the disease. The panel was narrowed to 26 genes with significant evidence of mechanistic potential in IBD, which were then categorized into specific areas of pathogenesis. These include gut barrier breakdown, inappropriate recognition of commensal bacteria, immune cell activation, proinflammatory cytokine release, and subsequent impairment of the anti-inflammatory response. The eventual goal of this paper is the creation of a customized panel of IBD genes that can be used to better understand the genetic mechanism of IBD and aid in the development of future therapies in IBD.

Retinoid orphan receptor gamma t (rorγt) promotes inflammatory eosinophilia but is dispensable for innate immune-mediated colitis

Inflammatory bowel diseases (IBD) result from uncontrolled inflammation in the intestinal mucosa leading to damage and loss of function. Both innate and adaptive immunity contribute to the inflammation of IBD and innate and adaptive immune cells reciprocally activate each other in a forward feedback loop. In order to better understand innate immune contributions to IBD, we developed a model of spontaneous 100% penetrant, early onset colitis that occurs in the absence of adaptive immunity by crossing villin-TNFAIP3 mice to RAG1-/- mice (TRAG mice). This model is driven by microbes and features increased levels of innate lymphoid cells in the intestinal mucosa. To investigate the role of type 3 innate lymphoid cells (ILC3) in the innate colitis of TRAG mice, we crossed them to retinoid orphan receptor gamma t deficient (Rorγt-/-) mice. Rorγt-/- x TRAG mice exhibited markedly reduced eosinophilia in the colonic mucosa, but colitis persisted in these mice. Colitis in Rorγt-/- x TRAG mice was characterized by increased infiltration of the intestinal mucosa by neutrophils, inflammatory monocytes, macrophages and other innate cells. RNA and cellular profiles of Rorγt-/- x TRAG mice were consistent with a lack of ILC3 and ILC3 derived cytokines, reduced antimicrobial factors, increased activation oof epithelial repair processes and reduced activation of epithelial cell STAT3. The colitis in Rorγt-/- x TRAG mice was ameliorated by antibiotic treatment indicating that microbes contribute to the ILC3-independent colitis of these mice. Together, these gene expression and cell signaling signatures reflect the double-edged sword of ILC3 in the intestine, inducing both proinflammatory and antimicrobial protective responses. Thus, Rorγt promotes eosinophilia but Rorγt and Rorγt-dependent ILC3 are dispensable for the innate colitis in TRAG mice.

Scaffold Proteins in Autoimmune Disorders

Cells transmit information to the external environment and within themselves through signaling molecules that modulate cellular activities. Aberrant cell signaling disturbs cellular homeostasis causing a number of different diseases, including autoimmunity. Scaffold proteins, as the name suggests, serve as the anchor for binding and stabilizing signaling proteins at a particular locale, allowing both intra and intercellular signal amplification and effective signal transmission. Scaffold proteins play a critical role in the functioning of tight junctions present at the intersection of two cells. In addition, they also participate in cleavage formation during cytokinesis, and in the organization of neural synapses, and modulate receptor management outcomes. In autoimmune settings such as lupus, scaffold proteins can lower the cell activation threshold resulting in uncontrolled signaling and hyperactivity. Scaffold proteins, through their binding domains, mediate protein- protein interaction and play numerous roles in cellular communication and homeostasis. This review presents an overview of scaffold proteins, their influence on the different signaling pathways, and their role in the pathogenesis of autoimmune and auto inflammatory diseases. Since these proteins participate in many roles and interact with several other signaling pathways, it is necessary to gain a thorough understanding of these proteins and their nuances to facilitate effective target identification and therapeutic design for the treatment of autoimmune disorders.

Analysis and identification of ferroptosis-related genes in ulcerative colitis

BACKGROUND

Previous studies have shown that ferroptosis is associated with the pathogenesis of ulcerative colitis (UC). Therefore, this study aimed to identify key ferroptosis-related genes (FRGs) associated with the diagnosis of UC.

METHODS

UC-related expression datasets were downloaded from the Gene Expression Omnibus (GEO) database. First, Weighted Gene Co-expression Network Analysis (WGCNA) was used to identify UC-related genes (UCRGs). Differentially expressed genes (DEGs) between normal and UC groups were screened in GSE87466, and DEGs were subjected to an intersection analysis with FRGs and UCRGs to obtain ferroptosis-related DEGs (FR DEGs). Then a protein-protein interaction (PPI) network was constructed for FR DEGs. The hub genes were extracted based on the degree, Maximum Neighborhood Component (MNC), closeness, and Maximal Clique Centrality (MCC). Biomarkers with diagnostic values were screened by support vector machine (SVM) and the least absolute shrinkage and selection operator (LASSO) algorithms. Next, the infiltration of immune cells was compared between UC and normal groups, and the correlation between different immune cells and diagnostic genes was analyzed. The biological functions, classical pathways, and intermolecular interaction networks of diagnostic genes were characterized utilizing ingenuity pathway analysis (IPA). Finally, a TF-mRNA network was constructed and potential small-molecule compounds were screened.

RESULTS

Thirty-six FR DEGs were obtained, and these were enriched in biological processes such as positive regulation of cytokine production, cytokine-mediated signalling pathway, long-chain fatty acid-CoA ligase activity, etc. Among 18 hub genes, five genes (ALOX5, TIMP1, TNFAIP3, SOCS1, DUOX2) were captured with diagnostic values for UC, and they displayed significant differences between UC and normal groups. Sixteen immune cell infiltrates were significantly different between UC and normal groups, such as activated dendritic cells and resting dendritic cells. TNFAIP3 and ALOX5 were positively correlated with neutrophils, and TIMP1, SOCS1, ALOX5, and DUOX2 were negatively correlated with M2 macrophages. IPA showed that diagnostic genes were related to 43 function modules and activated 17 pathways. The constructed TF-mRNA regulatory network comprised three diagnostic genes and 17 differentially expressed TFs. Potential small-molecule compounds including helveticoside and cymarin were identified.

CONCLUSION

Our findings yielded several promising FRGs for UC, providing a scientific reference for further studies on the pathogenesis of UC.

Transcriptome Analysis Reveals Immunomodulatory Effect of Spore-Displayed p75 on Human Intestinal Epithelial Caco-2 Cells

Lacticaseibacillus rhamnosus GG (LGG) can promote intestinal health by modulating the immune responses of the gastrointestinal tract. However, knowledge about the immunomodulatory action of LGG-derived soluble factors is limited. In our previous study, we have displayed LGG-derived p75 protein on the spore surface of Bacillus subtilis. The objective of this study was to determine the effect of spore-displayed p75 (CotG-p75) on immune system by investigating transcriptional response of Caco-2 cells stimulated by CotG-p75 through RNA-sequencing (RNA-seq). RNA-seq results showed that CotG-p75 mainly stimulated genes involved in biological processes, such as response to stimulus, immune regulation, and chemotaxis. KEGG pathway analysis suggested that many genes activated by CotG-p75 were involved in NF-ĸB signaling and chemokine signaling pathways. CotG-p75 increased cytokines and chemokines such as CXCL1, CXCL2, CXCL3, CXCL8, CXCL10, CCL20, CCL22, and IL1B essential for the immune system. In particular, CotG-p75 increased the expression levels of NF-ĸB-related genes such as NFKBIA, TNFAIP3, BIRC3, NFKB2, and RELB involved in immune and inflammatory responses. This study provides genes and pathways involved in immune responses influenced by CotG-p75. These comprehensive transcriptome profiling could be used to elucidate the immunomodulatory action of CotG-p75.

Lactobacillus johnsonii enhances the gut barrier integrity via the interaction between GAPDH and the mouse tight junction protein JAM-2

Commensal intestinal microbiota interacts with gut epithelial cells in the host by binding to specific host receptors. Several pattern recognition receptors on the gut that sense conserved microbial-associated molecular patterns have been reported; however, many of the gut receptor molecules involved in bacterial binding have not yet been identified. In this study, commensal intestinal bacteria interacting with mouse gut surface proteins were screened from fecal bacterial samples, to identify novel receptors on the epithelial cells in the mouse gut. Among the screened intestinal lactic acid bacteria, the frequently isolated Lactobacillus johnsonii MG was used for the purification of gut receptor proteins. An approximately 30 kDa protein was purified using affinity resin coupled surface layer proteins isolated from L. johnsonii MG. The purified gut protein was identified as a member of the tight junction protein family, junctional adhesion molecule-2 (JAM-2). As expected, the tight junctions of Caco-2 cells damaged by H₂O₂ were repaired by incubation with L. johnsonii MG. RNA sequence analysis showed significant upregulation of the expression of genes for tight junctions, anti-inflammatory effects, transcriptional regulation, and apoptosis in Caco-2 cells, following L. johnsonii MG treatment. In L. johnsonii MG, the surface layer 40 kDa protein was purified with gut protein-coupled affinity resin and identified as the moonlighting protein glyceraldehyde-3-phosphate dehydrogenase (GAPDH). These results suggest that L. johnsonii MG promotes the barrier function integrity in Caco-2 cells via GAPDH-JAM-2 binding. Here, we propose a promising approach to identify novel gut receptor molecules based on commensal bacterial interactions and understand host-bacterial communication in a mouse model.

LncRNA ALDB-898 modulates intestinal epithelial cell damage caused by Clostridium perfringens type C in piglet by regulating ssc-miR-122-5p/OCLN signaling

Diarrhea of piglets caused by Clostridium perfringens type C (C. perfringens type C) infection is a global problem afflicting piglet production. Long noncoding RNA (LncRNA) and microRNA (miRNA) have emerged as critical regulators of this pathological process, but the underlying molecular mechanisms remain unclear. In this study, we first observed the expression changes of ALDBSSCG0000000898 (ALDB-898) and ssc-miR-122-5p in infected ileum tissue of piglets with C. perfringens type C, and then used C. perfringens beta2 toxin (CPB2) to induce intestinal porcine epithelial cells (IPEC-J2) to construct an injury model. Cytometry kit 8 (CCK-8), lactate dehydrogenase (LDH), real-time quantitative polymerase chain reaction (RT-qPCR), Western blot, flow cytometry and fluorescein isothiocyanate-dextran 4 (FITC-Dextran 4) flux assays were performed to study the effect of ALDB-898 and ssc-miR-122-5p in apoptosis, inflammation and intestinal barrier damage and inflammatory in IPEC-J2 cells induced by CPB2. In addition, dual-luciferase reporter gene analysis was performed to confirm the relationship between ssc-miR-122-5p and ALDB-898 or ssc-miR-122-5p and occludin (OCLN), respectively. There were lower expression levels of ALDB-898 and OCLN and higher expression levels of ssc-miR-122-5p in diarrhea piglets caused by Clostridium perfringens type C. ALDB-898 and OCLN were significantly decreased and ssc-miR-122-5p was increased in IPEC-J2 after exposure to the CPB2 in a dose- and time-dependent manner. ALDB-898 overexpression mitigated CPB2-induced cell injury by promoting viability, restraining apoptosis, cytotoxicity, and inflammatory response, as well as weakening the destruction of the intestinal barrier. Further mechanisms disclosed that ALDB-898 functioned as a competing endogenous RNA (ceRNA) via binding to ssc-miR-122-5p, and OCLN was a target of ssc-miR-122-5p. Importantly, the ssc-miR-122-5p mimic led to abolishing the protective function of ALDB-898 on CPB2-induced IPEC-J2 cell damage, and the addition of OCLN reversed the negative impact of ssc-miR-122-5p, thereby restoring the protection of ALDB-898. Our data showed that ALDB-898 could enhance the expression of OCLN through competitive binding ssc-miR-122-5p to suppress CPB2-induced damage. The ALDB-898/ssc-miR-122-5p/OCLN signaling may be a candidate therapeutic pathway for diarrhea of piglets.

Effects of golden tomato extract on skin appearance-outlook into gene expression in cultured dermal fibroblasts and on trans-epidermal water loss and skin barrier in human subjects

SCOPE

Two experiments were performed to test the effects of rich tomato extract (Golden Tomato Extract, GTE) on human skin. In one experiment, the effects of this extract on gene expression in cultured human dermal fibroblasts were examined. In a second experiment, human subjects consumed the extract and trans-epidermal water loss (TEWL), and aspects of skin appearance were monitored.

METHODS AND RESULTS

Primary human dermal fibroblasts in culture were treated with the extract. After six hours, RNA was extracted, and gene expression was examined using Affymetrix Human Clariom D array processing. For the clinical study, 65 human subjects consumed a capsule once a day for 16 weeks, and various skin parameters were assessed at predetermined time intervals. Among the genes upregulated by GTE are genes that augment innate immunity, enhance DNA repair, and the ability to detoxify xenobiotics. GTE significantly reduced TEWL in subjects who had high TEWL at baseline, but it had no effect on TEWL in subjects who had lower TEWL at baseline.

CONCLUSIONS

Golden tomato extract may provide benefits to the skin by enhancing innate immunity and other defense mechanisms in the dermis and by providing antioxidants to the skin surface to optimize TEWL and the appearance of the skin.

The Multi-Omics Analysis Revealed a Metabolic Regulatory System of Cecum in Rabbit with Diarrhea

With the comprehensive prohibition of antibiotics in the feed industry in China, the incidence of diarrhea in rabbits increased, such as loss of appetite, vomiting, and excretion of atheromatous feces. In order to explore the pathological and the molecular mechanisms of the diarrhea in the rabbitry fed with antibiotic-free diet, we used microbial metagenomics, transcriptome, and non-targeted metabolomics sequencing. The results showed that the Firmicutes level was significantly decreased (p < 0.001) and the Proteobacteria level was significantly increased (p < 0.05). The functional enrichment of cecum revealed that most differentially expressed genes (DEGs) were expressed in immune, inflammatory, and metabolic processes. The enrichment of the cecal fecal metabolites focused on the bile secretion, antifolate resistance, and tryptophan metabolism pathways, which are mainly associated with inflammation. The results of correlation analysis showed that Fournierella was positively correlated with myricetin, ursolic acid, and furtherly might cause bile secretion and tryptophan metabolism disorder, aggravate intestinal inflammation, change intestinal permeability, and reduce host immunity, leading to diarrhea in rabbits. This study provides a theoretical basis for illustrating the reason for diarrhea and developing new feeds for the health of rabbits.

Altered microbial biogeography in an innate model of colitis

Changes in the spatial organization, or biogeography, of colonic microbes have been observed in human inflammatory bowel disease (IBD) and mouse models of IBD. We have developed a mouse model of IBD that occurs spontaneously and consistently in the absence of adaptive immunity. Mice expressing tumor necrosis factor-induced protein 3 (TNFAIP3) in intestinal epithelial cells (villin-TNFAIP3) develop colitis when interbred with Recombination Activating 1-deficient mice (RAG1^-/-). The colitis in villin-TNFAIP3 × RAG1^-/- (TRAG) mice is prevented by antibiotics, indicating a role for microbes in this innate colitis. We therefore explored the biogeography of microbes and responses to antibiotics in TRAG colitis. Laser capture microdissection and 16S rRNA sequencing revealed altered microbial populations across the transverse axis of the colon as the inner mucus layer of TRAG, but not RAG1^-/-, mice was infiltrated by microbes, which included increased abundance of the classes Gammaproteobacteria and Actinobacteria. Along the longitudinal axis differences in the efficacy of antibiotics to prevent colitis were evident. Neomycin was most effective for prevention of inflammation in the cecum, while ampicillin was most effective in the proximal and distal colon. RAG1^-/-, but not TRAG, mice exhibited a structured pattern of bacterial abundance with decreased Firmicutes and Proteobacteria but increased Bacteroidetes along the proximal to distal axis of the gut. TRAG mice exhibited increased relative abundance of potential pathobionts including <i>Bifidobacterium animalis</i> along the longitudinal axis of the gut whereas others, like <i>Helicobacter hepaticus</i> were increased only in the cecum. Potential beneficial organisms including <i>Roseburia</i> were decreased in the proximal regions of the TRAG colon, while <i>Bifidobacterium pseudolongulum</i> was decreased in the TRAG distal colon. Thus, the innate immune system maintains a structured, spatially organized, gut microbiome along the transverse and longitudinal axis of the gut, and disruption of this biogeography is a feature of innate immune colitis.

The functional role of miRNAs in inflammatory pathways associated with intestinal epithelial tight junction barrier regulation in IBD

Inflammatory bowel disease – Crohn's disease and ulcerative colitis – is an immune-mediated chronic disorder with still not fully elucidated complex mechanisms of pathogenesis and pathophysiology. Intestinal epithelial barrier (IEB) dysregulation is one of the major underlying mechanisms of inflammatory process induction in IBD. Proper IEB integrity is maintained to a large extent by intercellular tight junctions, the function of which can be modified by many molecules, including miRNAs. MiRNAs belong to noncoding and non-messenger RNAs, which can modulate gene expression by binding predicted mRNAs.

In this review, we summarize and discuss the potential role of miRNAs in the regulation of inflammatory signaling pathways affecting the function of the intestinal epithelial barrier in IBD, with particular emphasis on therapeutic potentials. The aim of the review is also to determine the further development directions of the studies on miRNA in the modulation of the intestinal epithelial barrier in IBD.

The Role of E3 Ubiquitin Ligases and Deubiquitinases in Inflammatory Bowel Disease: Friend or Foe?

Inflammatory bowel disease (IBD), which include Crohn’s disease (CD) and ulcerative colitis (UC), exhibits a complex multifactorial pathogenesis involving genetic susceptibility, imbalance of gut microbiota, mucosal immune disorder and environmental factors. Recent studies reported associations between ubiquitination and deubiquitination and the occurrence and development of inflammatory bowel disease. Ubiquitination modification, one of the most important types of post-translational modifications, is a multi-step enzymatic process involved in the regulation of various physiological processes of cells, including cell cycle progression, cell differentiation, apoptosis, and innate and adaptive immune responses. Alterations in ubiquitination and deubiquitination can lead to various diseases, including IBD. Here, we review the role of E3 ubiquitin ligases and deubiquitinases (DUBs) and their mediated ubiquitination and deubiquitination modifications in the pathogenesis of IBD. We highlight the importance of this type of posttranslational modification in the development of inflammation, and provide guidance for the future development of targeted therapeutics in IBD.

Targeting RIP Kinases in Chronic Inflammatory Disease

Chronic inflammatory disorders are characterised by aberrant and exaggerated inflammatory immune cell responses. Modes of extrinsic cell death, apoptosis and necroptosis, have now been shown to be potent drivers of deleterious inflammation, and mutations in core repressors of these pathways underlie many autoinflammatory disorders. The receptor-interacting protein (RIP) kinases, RIPK1 and RIPK3, are integral players in extrinsic cell death signalling by regulating the production of pro-inflammatory cytokines, such as tumour necrosis factor (TNF), and coordinating the activation of the NOD-like receptor protein 3 (NLRP3) inflammasome, which underpin pathological inflammation in numerous chronic inflammatory disorders. In this review, we firstly give an overview of the inflammatory cell death pathways regulated by RIPK1 and RIPK3. We then discuss how dysregulated signalling along these pathways can contribute to chronic inflammatory disorders of the joints, skin, and gastrointestinal tract, and discuss the emerging evidence for targeting these RIP kinases in the clinic.

Modulation of NLRP3 Inflammasome Attenuated Inflammatory Response Associated to Diarrhea-Predominant Irritable Bowel Syndrome

Diarrhea-predominant irritable bowel syndrome (IBS-D) is a multifactorial chronic gastrointestinal disorder characterized by inflammation and immune response. In this context, NLRP3 over-activation is associated with a breakdown of enteric-immune balance related to IBS-D. The aim of this study was to evaluate the effect of the inflammasome inhibitor, BAY 11-7082, in a rat model of IBS-D. Syndrome was induced by intracolonic instillation of 1 mL 4% acetic acid at 8 cm proximal to the anus for 30 s and sacrificed 2 weeks after IBS-D induction. BAY 11-7082 (10 and 30 mg/kg) was administered daily by oral gavage. The results obtained showed that the treatment with BAY 11-7082 (30 mg/kg) significantly reduced tissue injury characterized by edema, neutrophil infiltration, and loss of colon structure. We demonstrated that BAY 11-7082 treatment inhibited NLRP3 inflammasome activation and NF-kB translocation, reducing inflammatory mediators. Moreover, treatment with BAY 11-7082 restored tight junction alteration following IBS-D induction and reduced the restraint stress. Taken together, our data demonstrate that IBS-D induced NLRP3 inflammasome pathway activation, accompanied by the production of proinflammatory response. The modulation of the inflammosome pathway with BAY 11-7082 inhibitor significantly reduced pathological signs of IBS-D, therefore, can be considered a valuable strategy to reduce the development of IBS-D.

Preserving immune homeostasis with A20

A20/TNFAIP3 is a TNF induced gene that plays a profound role in preserving cellular and organismal homeostasis (Lee, et al., 2000; Opipari etal., 1990). This protein has been linked to multiple human diseases via genetic, epigenetic, and an emerging series of patients with mono-allelic coding mutations. Diverse cellular functions of this pleiotropically expressed protein include immune-suppressive, anti-inflammatory, and cell protective functions. The A20 protein regulates ubiquitin dependent cell signals; however, the biochemical mechanisms by which it performs these functions is surprisingly complex. Deciphering these cellular and biochemical facets of A20 dependent biology should greatly improve our understanding of murine and human disease pathophysiology as well as unveil new mechanisms of cell and tissue biology.

Differential miRNA-Gene Expression in M Cells in Response to Crohn's Disease-Associated AIEC

Adherent-invasive Escherichia coli (AIEC), which abnormally colonize the ileal mucosa of Crohn’s disease (CD) patients, are able to invade intestinal epithelial cells (IECs) and translocate through M cells overlying Peyer’s patches. The levels of microRNA (miRNA) and gene expression in IECs and M cells upon AIEC infection have not been investigated. Here, we used human intestinal epithelial Caco-2 monolayers and an in vitro M-cell model of AIEC translocation to analyze comprehensive miRNA and gene profiling under basal condition and upon infection with the reference AIEC LF82 strain. Our results showed that AIEC LF82 translocated through M cells but not Caco-2 monolayers. Both differential gene expression and miRNA profile in M cells compared to Caco-2 cells were obtained. In addition, AIEC infection induces changes in gene and miRNA profiles in both Caco-2 and M cells. In silico analysis showed that certain genes dysregulated upon AIEC infection were potential targets of AIEC-dysregulated miRNAs, suggesting a miRNA-mediated regulation of gene expression during AIEC infection in Caco-2, as well as M cells. This study facilitates the discovery of M cell-specific and AIEC response-specific gene-miRNA signature and enhances the molecular understanding of M cell biology under basal condition and in response to infection with CD-associated AIEC.

A20 Restores Impaired Intestinal Permeability and Inhibits Th2 Response in Mice with Colitis

BACKGROUND/AIMS

The etiology of inflammatory bowel disease is multifactorial and still obscure. The protective role of ubiquitin E3 ligase A20 (A20) in colitis needs to be further elucidated. This study aimed to investigate whether A20 exogenous administration restored impaired intestinal permeability and inhibited T helper (Th)2 response in mice with colitis.

METHODS

The effect of A20 overexpression in colonic mucosa on epithelial barrier function and T cell differentiation was evaluated in mice with dextran sulfate sodium (DSS)-induced chronic colitis.

RESULTS

A20 rectal treatment alleviated DSS-induced chronic colitis and restored impaired intestinal permeability. Oral challenge with 2% DSS elicited a Th2-type response in mice with colitis, and A20 rectal treatment inhibited CD4⁺ interleukin (IL)-4⁺ T cell differentiation and proliferation. In addition, the RNA expressions of Th2-related costimulatory molecular T-cell immunoglobulin and mucin domain (TIM)-1 and IL-4 were suppressed, while thrombospondin (TSP)-1 and interferon (IFN)-γ expressions were upregulated, after A20 rectal administration.

CONCLUSION

A20 rectal treatment restores impaired intestinal permeability and inhibits activated Th2 cell response in mice with colitis.

MicroRNA23a Overexpression in Crohn's Disease Targets Tumour Necrosis Factor Alpha Inhibitor Protein 3, Increasing Sensitivity to TNF and Modifying the Epithelial Barrier

BACKGROUND AND AIMS

Mucosal healing is important in Crohn's disease therapies. Epithelial homeostasis becomes dysregulated in Crohn's, with increased permeability, inflammation, and diarrhoea. MicroRNAs are small non-coding RNAs that regulate gene expression and show changes in inflammatory bowel disease. Tumour necrosis factor alpha [TNFα] inhibitor protein 3 is raised in Crohn's and regulates TNFα-mediated activation of NFκB. We investigated TNFα regulation by microRNA in Crohn's disease [CD], and studied effects on epithelial permeability and inflammation.

METHODS

Colonic epithelium from CD and healthy donor biopsies was isolated using laser capture microdissection, and microRNA was quantified. Tumour necrosis factor alpha inhibitor protein 3 was characterised immunohistochemically on serial sections. Expression effect of microRNA was confirmed with luciferase reporter assays. Functional barrier permeability studies and innate cytokine release were investigated with cell and explant culture studies.

RESULTS

MicroRNA23a levels significantly increased in colonic Crohn's epithelium compared with healthy epithelium. Luciferase reporter assays in transfected epithelial cells confirmed that microRNA23a repressed expression via the 3' untranslated region of tumour necrosis factor alpha inhibitor protein 3 mRNA, coinciding with increased NFκB-mediated transcription. Immunohistochemical staining of TNFAIP3 protein in colonic biopsies was reduced or absent in adjacent Crohn's sections, correlating inversely with microRNA23a levels and encompassing some intercohort variation. Overexpression of microRNA23a increased epithelial barrier permeability in a colonic epithelial model and increased inflammatory cytokine release in cultured explant biopsies, mimicking Crohn's disease characteristics.

CONCLUSIONS

MicroRNA23a overexpression in colonic Crohn's epithelium represses tumour necrosis factor alpha inhibitor protein 3, enhancing sensitivity to TNFα, with increased intestinal permeability and cytokine release.

A20 at the Crossroads of Cell Death, Inflammation, and Autoimmunity

A20 is a potent anti-inflammatory protein, acting by inhibiting nuclear factor κB (NF-κB) signaling and inflammatory gene expression and/or by preventing cell death. Mutations in the A20/TNFAIP3 gene have been associated with a plethora of inflammatory and autoimmune pathologies in humans and in mice. Although the anti-inflammatory role of A20 is well accepted, fundamental mechanistic questions regarding its mode of action remain unclear. Here, we review new findings that further clarify the molecular and cellular mechanisms by which A20 controls inflammatory signaling and cell death, and discuss new evidence for its involvement in inflammatory and autoimmune disease development.

Integrating Pharmacology and Gut Microbiota Analysis to Explore the Mechanism of Citri Reticulatae Pericarpium Against Reserpine-Induced Spleen Deficiency in Rats

Citri Reticulatae Pericarpium (CRP), dried peels of Citrus reticulata Blanco and its cultivars, is an important traditional Chinese medicine for the treatment of spleen deficiency-related diseases. To date, the mechanism of CRP alleviating spleen deficiency has not been well investigated. This study aimed to explore corresponding mechanisms with integrating pharmacology and gut microbiota analysis. Firstly, the therapeutic effects of CRP against spleen deficiency were evaluated in reserpine-treated rats. CRP was found to effectively relieve the typical symptoms of spleen deficiency, including poor digestion and absorption capacity, and disorder in gastrointestinal hormones, immune cytokines and oxidative stress. Secondly, high throughput 16S rRNA gene sequencing revealed that CRP could not only up-regulate some short-chain fatty acids producing and anti-inflammatory bacteria but also down-regulate certain spleen deficiency aggravated related bacteria, eventually led to the rebalance of gut microbiota in spleen deficiency rats. In addition, a total of 49 compounds derived from CRP were identified in rat urine using ultra-high performance liquid chromatography-quadrupole- time of flight tandem mass spectrometry. Network pharmacology analysis showed that apigenin, luteolin, naringenin, hesperidin, hesperetin, homoeriodictyol, dihydroxy-tetramethoxyflavone, and monohydroxy-tetramethoxyflavone were the core bioactive components for CRP against spleen deficiency. Further Gene Ontology analysis and pathway enrichment suggested that therapeutic effects of CRP against spleen deficiency involved multiple pathways such as tumor necrosis factor signaling, hypoxia-inducible factor-1 signaling and Toll-like receptor signaling pathway. These results would help to understand the mechanism of CRP alleviating spleen deficiency and provide a reference for further studies.

A De Novo Frameshift Mutation in TNFAIP3 Impairs A20 Deubiquitination Function to Cause Neuropsychiatric Systemic Lupus Erythematosus

PURPOSE

Genome-wide association study of systemic lupus erythematosus (SLE) revealed tumor necrosis factor alpha-induced protein 3 (TNFAIP3, A20) as a susceptibility gene. Here, we report a de novo mutation in TNFAIP3 in a Chinese patient with neuropsychiatric SLE (NPSLE).

METHODS

Whole exome sequencing was performed for the patient and healthy members from the family. Suspected pathogenic variants were further analyzed and co-segregation was confirmed by Sanger sequencing. Real-time PCR and western blot were performed with peripheral blood mononuclear cells (PBMCs) and patient-derived T cells. Transfected HEK293T cells, human umbilical vein endothelial cells, normal human astrocytes, and microglia were used for in vitro studies.

RESULTS

A de novo frameshift mutation in TNFAIP3 was found in the NPSLE patient. Western blot analysis showed activated NF-κB and mitogen-activated protein kinase pathways. Real-time PCR revealed elevated expression of pro-inflammatory cytokines. On immunoprecipitation assay, the mutant A20 altered the K63-linked ubiquitin level of TRAF6 via its ubiquitin-editing function.

CONCLUSIONS

The mutant A20 may play a role in weakening the tight junction of the blood-brain barrier to cause neurologic symptoms. We report a rare variant of TNFAIP3 in a patient with NPSLE and reveal its autoimmune disease-causing mechanism in both peripheral tissues and the central nervous system.

Dysregulation of Intestinal Epithelial Cell RIPK Pathways Promotes Chronic Inflammation in the IBD Gut

Crohn's disease (CD) and ulcerative colitis (UC) are common intestinal bowel diseases (IBD) characterized by intestinal epithelial injury including extensive epithelial cell death, mucosal erosion, ulceration, and crypt abscess formation. Several factors including activated signaling pathways, microbial dysbiosis, and immune deregulation contribute to disease progression. Although most research efforts to date have focused on immune cells, it is becoming increasingly clear that intestinal epithelial cells (IEC) are important players in IBD pathogenesis. Aberrant or exacerbated responses to how IEC sense IBD-associated microbes, respond to TNF stimulation, and regenerate and heal the injured mucosa are critical to the integrity of the intestinal barrier. The role of several genes and pathways in which single nucleotide polymorphisms (SNP) showed strong association with IBD has recently been studied in the context of IEC. In patients with IBD, it has been shown that the expression of specific dysregulated genes in IECs plays an important role in TNF-induced cell death and microbial sensing. Among them, the NF-κB pathway and its target gene TNFAIP3 promote TNF-induced and receptor interacting protein kinase (RIPK1)-dependent intestinal epithelial cell death. On the other hand, RIPK2 functions as a key signaling protein in host defense responses induced by activation of the cytosolic microbial sensors nucleotide-binding oligomerization domain-containing proteins 1 and 2 (NOD1 and NOD2). The RIPK2-mediated signaling pathway leads to the activation of NF-κB and MAP kinases that induce autophagy following infection. This article will review these dysregulated RIPK pathways in IEC and their role in promoting chronic inflammation. It will also highlight future research directions and therapeutic approaches involving RIPKs in IBD.

How lifestyle factors and their associated pathogenetic mechanisms impact psoriasis

BACKGROUNDS AND AIMS

Psoriasis is a skin disorder affecting approximately 2-3% of the global population. While research has revealed a strong genetic component, there are few studies exploring the extent to which lifestyle factors influence psoriasis pathogenesis. The aim of this review was to describe the role of lifestyle factors as both a potential cause and treatment for psoriasis. The review also examines the underlying mechanisms through which these lifestyle factors may operate.

METHODS

This narrative review aims to incorporate current knowledge relating to both lifestyle and pathogenetic factors that contribute to and alleviate psoriasis presentation. Studies reporting the effect of an inflammatory diet and potential dietary benefits are reported, as well as insights into the effects of stress, smoking and alcohol, insulin resistance and exercise.

RESULTS

Poor nutrition and low Omega 3 fatty acid intake, likely combined with fat malabsorption caused by gut dysbiosis and systemic inflammation, are associated with psoriasis. The data strongly suggest that improvements to disease severity can be made through dietary and lifestyle interventions and increased physical activity. Less conclusive, although worthy of mention, is the beneficial effect of bile acid supplementation.

CONCLUSIONS

Lifestyle interventions are a promising treatment for psoriasis and its associated co-morbidities. However, gaps and inadequacies exist within the literature, e.g. methodology, absence of a unified scoring system, lack of controlled clinical data and lack of studies without simultaneous usage of biologics or alternative therapies. Future directions should focus on high quality cohort studies and clinical trials.

Elevated A20 promotes TNF-induced and RIPK1-dependent intestinal epithelial cell death

Intestinal epithelial cell (IEC) death is a common feature of inflammatory bowel disease (IBD) that triggers inflammation by compromising barrier integrity. In many patients with IBD, epithelial damage and inflammation are TNF-dependent. Elevated TNF production in IBD is accompanied by increased expression of the TNFAIP3 gene, which encodes A20, a negative feedback regulator of NF-κB. A20 in intestinal epithelium from patients with IBD coincided with the presence of cleaved caspase-3, and A20 transgenic (Tg) mice, in which A20 is expressed from an IEC-specific promoter, were highly susceptible to TNF-induced IEC death, intestinal damage, and shock. A20-expressing intestinal organoids were also susceptible to TNF-induced death, demonstrating that enhanced TNF-induced apoptosis was a cell-autonomous property of A20. This effect was dependent on Receptor Interacting Protein Kinase 1 (RIPK1) activity, and A20 was found to associate with the Ripoptosome complex, potentiating its ability to activate caspase-8. A20-potentiated RIPK1-dependent apoptosis did not require the A20 deubiquitinase (DUB) domain and zinc finger 4 (ZnF4), which mediate NF-κB inhibition in fibroblasts, but was strictly dependent on ZnF7 and A20 dimerization. We suggest that A20 dimers bind linear ubiquitin to stabilize the Ripoptosome and potentiate its apoptosis-inducing activity.

The JAK inhibitor ruxolitinib reduces inflammation in an ILC3-independent model of innate immune colitis

Innate immunity contributes to the pathogenesis of inflammatory bowel disease (IBD). However, the mechanisms of IBD mediated by innate immunity are incompletely understood and there are limited models of spontaneous innate immune colitis to address this question. Here we describe a new robust model of colitis occurring in the absence of adaptive immunity. RAG1-deficient mice expressing TNFAIP3 in intestinal epithelial cells (TRAG mice) spontaneously developed 100% penetrant, early-onset colitis that was limited to the colon and dependent on intestinal microbes but was not transmissible to co-housed littermates. TRAG colitis was associated with increased mucosal numbers of innate lymphoid cells (ILCs) and depletion of ILC prevented colitis in TRAG mice. ILC depletion also therapeutically reversed established colitis in TRAG mice. The colitis in TRAG mice was not prevented by interbreeding to mice lacking group 3 ILC nor by depletion of TNF. Treatment with the JAK inhibitor ruxolitinib ameliorated colitis in TRAG mice. This new model of colitis, with its predictable onset and colon-specific inflammation, will have direct utility in developing a more complete understanding of innate immune mechanisms that can contribute to colitis and in pre-clinical studies for effects of therapeutic agents on innate immune-mediated IBD.

Tumor necrosis factor α-induced protein 3 (A20) is dysregulated in pediatric Crohn disease

PURPOSE

A significant feature of pediatric inflammatory bowel diseases (IBD), which include Crohn disease (CD), and ulcerative colitis (UC), is failure to suppress inflammation. The inability to regulate inflammation renders a major challenge toward establishing effective treatments in IBD. Nuclear factor kappa-light-chain-enhancer of activated B-cells-induced inflammation is inhibited by A20 through interactions with TAX1BP1 (Tax1-binding protein 1) and A20-binding inhibitor of NF-κβ activation (ABIN)-1 (A20 binding and inhibitor of NF-κβ) and upon phosphorylation by inhibitor of nuclear factor kappa-β kinase subunit beta (IKKβ), which stabilizes it. We hypothesized that dysregulation of A20 is an important factor in uncontrolled inflammation in pediatric IBD.

PATIENTS AND METHODS

Gene expression of A20, IKKβ, ABIN-1, TAX1BP1, A20 protein, cytokine levels, and A20 phosphorylation was analyzed in the terminal ileum (TI) of 39 patients (14 non-IBD, 15 CD, and 10 UC). A20 expression and protein in T-84 cells and ex vivo biopsies of patients were measured after treatment with Escherichia coli strains or tumor necrosis factor (TNF)-α.

RESULTS

TNF-α levels and A20 expression were increased in the TI of CD patients. A20 protein levels and ABIN-1 expression were low, TAX1BP1 expression was high, and IKKβ was unchanged. A20 expression positively correlated with biopsy TNF-α levels and inflammatory markers in CD patients. A20 phosphorylation appeared lower in CD patients. A20 expression in TI biopsies from CD patients and T84 cells was triggered with E. coli, strain LF82, while A20 protein levels remained unchanged.

CONCLUSION

We describe a potential mechanism related to failure of A20 to suppress inflammation in CD, characterized by high A20 expression and low A20 protein levels. The dysregulation of A20 is potentially due to alterations in ABIN-1, and infection with E. coli strain LF82 could affect the function and stability of A20. Our study signifies an important finding in A20 regulation in IBD, which prevents it from suppressing inflammation.

A20 upregulation during treated HIV disease is associated with intestinal epithelial cell recovery and function

TRIAL REGISTRATION

ClinicalTrials.gov Clinical Trial NCT00594880.

Serological, genetic and clinical associations with increased health-care resource utilization in inflammatory bowel disease

OBJECTIVE

Inflammatory bowel diseases (IBD) are associated with significant morbidity and economic burden. The variable course of IBD creates a need for predictors of clinical outcomes and health resource utilization (HRU) to guide treatment decisions. We aimed to identify clinical, serological or genetic markers associated with inpatient resource utilization in patients with ulcerative colitis (UC) and Crohn's disease (CD).

METHODS

Patients with IBD with available genetic and serological data who had at least one emergency department visit or hospitalization in a 3-year period were included. The primary outcome measure was HRU, as measured by the All Patient Refined Diagnosis Related Group classification system. Univariate and multivariate linear and logistic regression models were used to identify the associations with HRU.

RESULTS

Altogether 858 (562 CD and 296 UC) patients were included. Anti-CBir1 seropositivity (P = 0.002, effect size [ES]: 0.762, 95% confidence interval [CI] 0.512-1.012) and low socioeconomic status (P = 0.005, ES: 1.620 [95% CI 1.091-2.149]) were independently associated with a high HRU. CD diagnosis (P = 0.006, ES: -0.701 [95% CI -0.959 to -0.443]) was independently associated with a low inpatient HRU.

CONCLUSION

In patients with IBD who required at least one emergency department visit or hospitalization, anti-CBir1 antibody status may be a useful biomarker of HRU when formulating management strategies to reduce disease complications and resource utilization.

Altered expression of Tumor Necrosis Factor Alpha -Induced Protein 3 correlates with disease severity in Ulcerative Colitis

Ulcerative colitis (UC), an inflammatory disorder of the colon arises from dysregulated immune response towards gut microbes. Transcription factor NFκB is a major regulatory component influencing mucosal inflammation. We evaluated expression of Tumor Necrosis Factor Alpha Induced Protein3 (TNFAIP3), the inhibitor of NFκB activation and its associated partners ITCH, RNF11 and Tax1BP1 in inflamed mucosa of UC patients. We found highly significant up-regulated mRNA expression of TNFAIP3 that negatively correlated with disease activity in UC. mRNA levels of ITCH, RNF11 and Tax1BP1 were significantly down-regulated. Significant positive correlation with disease activity was noted for Tax1BP1. All four genes showed significant down-regulation at protein level. mRNA levels of inducers of TNFAIP3 expression, NFκB p65 subunit and MAST3 was determined. There was significant increase in p65 mRNA expression and down-regulated MAST3 expression. This suggested that increase in NFκB expression regulates TNFAIP3 levels. Deficiency of TNFAIP3 expression resulted in significant up-regulation of NFκB p65 sub-unit as well as its downstream genes such as iNOS, an inflammatory marker, inhibitors of apoptosis like cIAP2 and XIAP and mediators of anti-apoptotic signals TRAF1 and TRAF2. Taken together, decreased expression of TNFAIP3 and its partners contribute to inflammation and up-regulation of apoptosis inhibitors that may create microenvironment for colorectal cancer.

Antioxidant and anti-inflammatory effects of zinc. Zinc-dependent NF-κB signaling

Zinc is a nutritionally fundamental trace element, essential to the structure and function of numerous macromolecules, including enzymes regulating cellular processes and cellular signaling pathways. The mineral modulates immune response and exhibits antioxidant and anti-inflammatory activity. Zinc retards oxidative processes on a long-term basis by inducing the expression of metallothioneins. These metal-binding cysteine-rich proteins are responsible for maintaining zinc-related cell homeostasis and act as potent electrophilic scavengers and cytoprotective agents. Furthermore, zinc increases the activation of antioxidant proteins and enzymes, such as glutathione and catalase. On the other hand, zinc exerts its antioxidant effect via two acute mechanisms, one of which is the stabilization of protein sulfhydryls against oxidation. The second mechanism consists in antagonizing transition metal-catalyzed reactions. Zinc can exchange redox active metals, such as copper and iron, in certain binding sites and attenuate cellular site-specific oxidative injury. Studies have demonstrated that physiological reconstitution of zinc restrains immune activation, whereas zinc deficiency, in the setting of severe infection, provokes a systemic increase in NF-κB activation. In vitro studies have shown that zinc decreases NF-κB activation and its target genes, such as TNF-α and IL-1β, and increases the gene expression of A20 and PPAR-α, the two zinc finger proteins with anti-inflammatory properties. Alternative NF-κB inhibitory mechanism is initiated by the inhibition of cyclic nucleotide phosphodiesterase, whereas another presumed mechanism consists in inhibition of IκB kinase in response to infection by zinc ions that have been imported into cells by ZIP8.

Preventing Overheating: Tight Control of Gut Innate Immunity in Health and Disease

Innate immune responses are key to maintain adequate host-microbial interactions. However, those signals are needed to efficiently trigger rapid and targeted antimicrobial responses in case of pathogen encounter. Several molecules have evolved to regulate intensity and coordinate signaling to avoid detrimental consequences to the host. Regulation can occur at the cell surface, within the cytoplasm, and at the transcriptional level. Innate immune regulation seems to be equally important than stimulation, as disruption of immunoregulatory molecules modulates the risk for several diseases. This is the case for colitis and inflammatory bowel disease but also colorectal cancer and intestinal infections. In this review, we recapitulate the molecular mechanisms underlying regulation of innate immune signals and mention their implications in several disease states including inflammatory bowel disease.

A20 plays a critical role in the immunoregulatory function of mesenchymal stem cells

Mesenchymal stem cells (MSCs) possess an immunoregulatory capacity and are a therapeutic target for many inflammation‐related diseases. However, the detailed mechanisms of MSC‐mediated immunosuppression remain unclear. In this study, we provide new information to partly explain the molecular mechanisms of immunoregulation by MSCs. Specifically, we found that A20 expression was induced in MSCs by inflammatory cytokines. Knockdown of A20 in MSCs resulted in increased proliferation and reduced adipogenesis, and partly reversed the suppressive effect of MSCs on T cell proliferation in vitro and inhibited tumour growth in vivo. Mechanistic studies indicated that knockdown of A20 in MSCs inhibited activation of the p38 mitogen‐activated protein kinase (MAPK) pathway, which potently promoted the production of tumour necrosis factor (TNF)‐α and inhibited the production of interleukin (IL)‐10. Collectively, these data reveal a crucial role of A20 in regulating the immunomodulatory activities of MSCs by controlling the expression of TNF‐α and IL‐10 in an inflammatory environment. These findings provide novel insights into the pathogenesis of various inflammatory‐associated diseases, and are a new reference for the future development of treatments for such afflictions.

Probiotic-derived polyphosphate improves the intestinal barrier function through the caveolin-dependent endocytic pathway

Probiotics exhibit beneficial functions for host homeostasis maintenance. We herein investigated the mechanism by which Lactobacillus brevis-derived poly P exhibited a beneficial function. Immunostaining indicated that poly P was captured in the plasma membrane via integrin β1 in Caco2/bbe cells. The uptake of poly P was reduced by the inhibition of integrin β1 as well as caveolin-1, a major component of lipid rafts. The function of poly P, including the induction of HSP27 and enhancement of the intestinal barrier function, was suppressed by the inhibition of caveolin-1, illustrating that the function of poly P was mediated by the endocytic pathway. High-throughput sequencing revealed that poly P induced tumor necrosis factor alpha-induced protein 3, which contributes to cytoprotection, including upregulation of the intestinal barrier function. The present study demonstrates a novel host-probiotic interaction through the uptake of bacterial substance into host cells, which is distinct from pattern recognition receptor pathways.

Correlation of Biomarker Expression in Colonic Mucosa with Disease Phenotype in Crohn's Disease and Ulcerative Colitis

BACKGROUND

Inflammatory bowel diseases (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), are characterized by chronic intestinal inflammation due to immunological, microbial, and environmental factors in genetically predisposed individuals. Advances in the diagnosis, prognosis, and treatment of IBD require the identification of robust biomarkers that can be used for molecular classification of diverse disease presentations. We previously identified five genes, RELA, TNFAIP3 (A20), PIGR, TNF, and IL8, whose mRNA levels in colonic mucosal biopsies could be used in a multivariate analysis to classify patients with CD based on disease behavior and responses to therapy.

AIM

We compared expression of these five biomarkers in IBD patients classified as having CD or UC, and in healthy controls.

RESULTS

Patients with CD were characterized as having decreased median expression of TNFAIP3, PIGR, and TNF in non-inflamed colonic mucosa as compared to healthy controls. By contrast, UC patients exhibited decreased expression of PIGR and elevated expression of IL8 in colonic mucosa compared to healthy controls. A multivariate analysis combining mRNA levels for all five genes resulted in segregation of individuals based on disease presentation (CD vs. UC) as well as severity, i.e., patients in remission versus those with acute colitis at the time of biopsy.

CONCLUSION

We propose that this approach could be used as a model for molecular classification of IBD patients, which could further be enhanced by the inclusion of additional genes that are identified by functional studies, global gene expression analyses, and genome-wide association studies.

Brain endothelial TAK1 and NEMO safeguard the neurovascular unit

Ridder et al. show that deletion of NEMO, a component of NF-kB signaling, in brain endothelial cells results in increased cerebral vascular permeability and endothelial cell death, and recapitulates the neurological symptoms observed in the genetic disease incontinentia pigmenti.

Inactivating mutations of the NF-κB essential modulator (NEMO), a key component of NF-κB signaling, cause the genetic disease incontinentia pigmenti (IP). This leads to severe neurological symptoms, but the mechanisms underlying brain involvement were unclear. Here, we show that selectively deleting Nemo or the upstream kinase Tak1 in brain endothelial cells resulted in death of endothelial cells, a rarefaction of brain microvessels, cerebral hypoperfusion, a disrupted blood–brain barrier (BBB), and epileptic seizures. TAK1 and NEMO protected the BBB by activating the transcription factor NF-κB and stabilizing the tight junction protein occludin. They also prevented brain endothelial cell death in a NF-κB–independent manner by reducing oxidative damage. Our data identify crucial functions of inflammatory TAK1–NEMO signaling in protecting the brain endothelium and maintaining normal brain function, thus explaining the neurological symptoms associated with IP.

Proinflammatory mediators alter expression of nuclear factor kappa B-regulating deubiquitinases in sinonasal epithelial cells

BACKGROUND

Nuclear factor κB (NF-κB) is a vital transcription factor that is activated by numerous inflammatory stimuli. Its activity is tightly regulated by a family of deubiquitinating enzymes (A20, Cezanne, cylindromatosis [CYLD]) that function in a negative-feedback loop, a process that prevents chronic and systemic inflammation. This study seeks to characterize the expression and functional role of NF-κB-regulating deubiquitinases in the sinonasal epithelium.

METHODS

Expression of A20, Cezanne, and CYLD was assessed in normal sinonasal tissue using immunohistochemistry. Cultured sinonasal epithelial cells (SNECs) were stimulated with proinflammatory cytokines (tumor necrosis factor α [TNF-α], interleukin 4 [IL]-4, IL-13) or lipopolysaccharide (LPS) and changes in NF-κB activation and deubiquitinase expression were assessed using Western blots and quantitative real-time polymerase chain reaction (qRT-PCR), respectively.

RESULTS

NF-κB was activated in response to LPS and TNF-α, but not IL-4 or IL-13. A20, Cezanne, and CYLD were all expressed in sinonasal tissue, primarily along the apical surface of the epithelium. Proinflammatory mediators primarily affected expression of A20, with upregulation by LPS and TNF-α and downregulation by IL-4 and IL-13.

CONCLUSION

The NF-κB-regulating deubiquitinases A20, Cezanne, and CYLD are expressed in sinonasal tissue and are differentially induced by proinflammatory cytokines and the microbial antigen, LPS. These results suggest an important role for NF-κB-regulating deubiquitinases in mucosal immunity and homeostasis.

Maternal high-zinc diet attenuates intestinal inflammation by reducing DNA methylation and elevating H3K9 acetylation in the A20 promoter of offspring chicks

A20 is an anti-inflammatory protein that suppresses ubiquitin-dependent nuclear factor κB (NF-κB) signaling, which can be regulated by the microelement zinc (Zn). In mammals, Zn deficiency contributes to a decrease in A20 abundance, which impairs the gut mucosa barrier. However, it is unclear whether the epigenetic reprogramming of the A20 promoter is involved in enhanced Zn-induced intestinal immunity, especially in avian species. Herein, we show that maternal organic Zn exposure resulted in significantly improved intestinal morphological characteristics, increased mucin 2 (MUC2) abundance and secretory IgA (sIgA) production in progeny jejunums. Maternal and offspring Zn supplementation partially alleviated Zn-deficiency-induced inflammatory response, accompanied by repression of NF-κB signaling. Additionally, we observed DNA hypomethylation and histone H3 at lysine 9 (H3K9) hyperacetylation at the A20 promoter region and subsequent activated A20 expression in Zn-supplemented hens compared with control. Notably, maternal dietary organic Zn exposure exhibited greater attenuation of gut impairment, along with increased MUC2 expression and sIgA level, and decreased the abundance of TNF-α and A20 relative to the inorganic-Zn group. Furthermore, enhanced acetylated H3K9 and A20 transcription at day 14 was found in the offspring adequate dietary Zn group. Thus, A20 may be a novel inflammatory-suppressed factor of chick gut that is persistently promoted by dietary Zn supplementation via epigenetic modifications at A20 promoter.

Intestinal epithelial expression of TNFAIP3 results in microbial invasion of the inner mucus layer and induces colitis in IL-10-deficient mice

Tumor necrosis factor-induced protein 3 (TNFAIP3; also known as A20) negatively regulates NF-κB and MAPK signals to control inflammatory responses. TNFAIP3 also protects against TNF-induced cell death. Intestinal epithelial cell (IEC) expression of TNFAIP3 improves barrier function and tight junction integrity and prevents dextran sulfate sodium (DSS)-induced IEC death and colitis. We therefore investigated the effects of TNFAIP3 expression in IEC on immune homeostasis in the intestines of immune-compromised mice. Villin-TNFAIP3 (v-TNFAIP3) transgenic mice were interbred with IL-10(-/-) mice (v-TNFAIP3 × IL-10(-/-)) and incidence, onset, and severity of colitis was assessed. v-TNFAIP3 × IL-10(-/-) mice displayed severe, early onset, and highly penetrant colitis that was not observed in IL-10(-/-) or v-TNFAIP3 mice. V-TNFAIP3 mice displayed altered expression of mucosal cytokines, increased numbers of mucosal regulatory T cells, and altered expression of mucosal antimicrobial peptides (AMPs). Microbial colonization of the inner mucus layer of v-TNFAIP3 mice was observed, along with alterations in the microbiome, but this was not sufficient to induce colitis in v-TNFAIP3 mice. The relative sterility of the inner mucus layer observed in wild-type and IL-10(-/-) mice was lost in v-TNFAIP3 × IL-10(-/-) mice. Thus IEC-derived factors, induced by signals that are inhibited by TNFAIP3, suppress the onset of inflammatory bowel disease in IL-10(-/-) mice. Our results indicate that IEC expression of TNFAIP3 alters AMP expression and allows microbial colonization of the inner mucus layer, which activates an IL-10-dependent anti-inflammatory process that is necessary to prevent colitis.

Intraluminal administration of poly I:C causes an enteropathy that is exacerbated by administration of oral dietary antigen

Systemic administration of polyinosinic:polycytidylic acid (poly I:C), mimics virally-induced activation of TLR3 signalling causing acute small intestine damage, but whether and how mucosal administration of poly I:C causes enteropathy is less clear. Our aim was to investigate the inflammatory pathways elicited after intraluminal administration of poly I:C and determine acute and delayed consequences of this locally induced immune activation. Intraluminal poly I:C induced rapid mucosal immune activation in C57BL/6 mice involving IFNβ and the CXCL10/CXCR3 axis, that may drive inflammation towards a Th1 profile. Intraluminal poly I:C also caused enteropathy and gut dysfunction in gliadin-sensitive NOD-DQ8 mice, and this was prolonged by concomitant oral administration of gliadin. Our results indicate that small intestine pathology can be induced in mice by intraluminal administration of poly I:C and that this is exacerbated by subsequent oral delivery of a relevant dietary antigen.

Pleiotropic functions of TNF-α in the regulation of the intestinal epithelial response to inflammation

An important function of intestinal epithelial cells (IECs) is to maintain the integrity of the mucosal barrier. Inflammation challenges the integrity of the mucosal barrier and the intestinal epithelium needs to adapt to a multitude of signals in order to perform the complex process of maintenance and restitution of its barrier function. Dysfunctions in epithelial barrier integrity and restoration contribute to the pathogenesis of inflammatory bowel diseases (IBDs) such as Crohn's disease and ulcerative colitis. Mucosal healing has developed to a significant treatment goal in IBD. In this review, we would like to highlight physiologic and pathologic adaptations of the intestinal epithelium to inflammation, exemplified by its responses to TNF-α. A large body of literature exists that highlights the diverse effects of this cytokine on IECs. TNF-α modulates intestinal mucus secretion and constitution. TNF-α stimulation modulates paracellular flow via tight junctional control. TNF-α induces intracellular signaling cascades that determine significant cell fate decisions such as survival, cell death or proliferation. TNF-α impacts epithelial wound healing in ErbB- and Wnt-dependent pathways while also importantly guiding immune cell attraction and function. We selected important studies from recent years with a focus on functional in vivo data providing crucial insights into the complex process of intestinal homeostasis.

Staphylococcal enterotoxin B suppresses Alix and compromises intestinal epithelial barrier functions

Background

The epithelial barrier dysfunction plays a critical role in the pathogenesis of a broad array of immune diseases. Alix protein is involved in the endolysosome system. This study aims to elucidate the role of Alix in the maintenance of epithelial barrier function.

Results

The results showed that Alix was detected in T84 cells at both mRNA and protein levels. Exposure to Staphylococcal enterotoxin B (SEB) markedly suppressed the expression of Alix in T84 cells, which could be blocked by knocking down the Toll like receptor 2. The exposure to SEB did not affect the TER, but markedly increased the permeability of T84 monolayers to OVA; the OVA passing through T84 monolayers still preserved the antigenicity manifesting inducing antigen specific T cells proliferation.

Conclusions

Alix protein plays a critical role in the maintenance of the barrier function of T84 monolayers.

Regulatory effect of zinc finger protein A20 on inflammation and apoptosis: Implications for inflammatory bowel disease

Zinc finger protein A20, also known as tumor necrosis factor alpha-induced protein 3 (TNFAIP3), is a protein with dual enzyme activities: ubiquitination and deubiquitination. It can negatively regulate inflammation and apoptosis mediated by a variety of signal transduction pathway, playing an important role in the occurrence, development and prognosis of inflammatory diseases, especially inflammatory bowel diseases. In recent years, the role of zinc finger protein A20 in inflammation and apoptosis has gained growing concern. This paper gives a brief overview of the biological effects of zinc finger protein A20 on inflammation and apoptosis mediated by tumor necrosis factor alpha/tumor necrosis factor receptor 1, nuclear factor kappa B, lipopolysaccharide/lipopolysaccharide - nuclear factor kappa B, oxidized low density lipoprotein and other pathways as well as the negative regulatory effect of zinc finger protein A20 on intestinal inflammation and epithelial apoptosis in inflammatory bowel disease.

A20 in inflammation and autoimmunity

Although known for many years as a nuclear factor (NF)-κB inhibitory and antiapoptotic signaling protein, A20 has recently attracted much attention because of its ubiquitin-regulatory activities and qualification by genome-wide association studies (GWASs) as a susceptibility gene for inflammatory disease. Here, we review new findings that have shed light on the molecular and biochemical mechanisms by which A20 regulates inflammatory signaling cascades, and discuss recent experimental evidence characterizing A20 as a crucial gatekeeper preserving tissue homeostasis.

Genomic correlates of variability in immune response to an oral cholera vaccine

Cholera is endemic to many countries. Recent major outbreaks of cholera have prompted World Health Organization to recommend oral cholera vaccination as a public-health strategy. Variation in percentage of seroconversion upon cholera vaccination has been recorded across populations. Vaccine-induced responses are influenced by host genetic differences. We have investigated association between single-nucleotide polymorphic (SNP) loci in and around 296 immunologically relevant genes and total anti-lipopolysaccharide (LPS) antibody response to a killed whole-cell vaccine, comprising LPS from multiple strains of Vibrio cholerae. Titers derived from standard vibriocidal assays were also analyzed to gain further insights on validated SNP associations. Vaccination was administered to 1000 individuals drawn from India. Data on two independent random subsets, each comprising ∼500 vaccinees, were used for discovery of genomic associations and validation, respectively. Significant associations of four SNPs and haplotypes in three genes (MARCO, TNFAIP3 and CXCL12) with AR were discovered and validated, of which two in TNFAIP3 and CXCL12 were also significantly associated with immunity (fourfold increase in vibriocidal titers). CXCL12 is a neutrophil and lymphocyte chemoattractant that is upregulated in response to V. cholerae infection. LPS in the vaccine possibly provides signals that mimic those of the live bacterium. TNFAIP3 promotes intestinal epithelial barrier integrity and provides tight junction protein regulation; possible requirements for adequate response to the vaccine. LPS is a potent activator of innate immune responses and a ligand of MARCO. Variants in this gene have been found to be associated with LPS response, but not with high vibriocidal titer level.