Temporally Distinct Functions of the Cytokines IL-12 and IL-23 Drive Chronic Colon Inflammation in Response to Intestinal Barrier Impairment

Lactobacillus reuteri 1 Enhances Intestinal Epithelial Barrier Function and Alleviates the Inflammatory Response Induced by Enterotoxigenic Escherichia coli K88 via Suppressing the MLCK Signaling Pathway in IPEC-J2 Cells

Intestinal epithelial barrier injury disrupts immune homeostasis and leads to many intestinal disorders. Lactobacillus reuteri (L. reuteri) strains can influence immune system development and intestinal function. However, the underlying mechanisms of L. reuteri LR1 that regulate inflammatory response and intestinal integrity are still unknown. The present study aimed to determine the effects of LR1 on the ETEC K88-induced intestinal epithelial injury on the inflammatory response, intestinal epithelial barrier function, and the MLCK signal pathway and its underlying mechanism. Here, we showed that the 1 × 109 cfu/ml LR1 treatment for 4 h dramatically decreased interleukin-8 (IL-8) and IL-6 expression. Then, the data indicated that the 1 × 108 cfu/ml ETEC K88 treatment for 4 h dramatically enhanced IL-8, IL-6, and tumor necrosis factor-α (TNF-α) expression. Furthermore, scanning electron microscope (SEM) data indicated that pretreatment with LR1 inhibited the ETEC K88 that adhered on IPEC-J2 and alleviated the scratch injury of IPEC J2 cells. Moreover, LR1 pretreatment significantly reversed the declined transepithelial electrical resistance (TER) and tight junction protein level, and enhanced the induction by ETEC K88 treatment. Additionally, LR1 pretreatment dramatically declined IL-8, IL-17A, IL-6, and TNF-α levels compared with the ETEC K88 group. Then, ETEC K88-treated IPEC-J2 cells had a higher level of myosin light-chain kinase (MLCK), higher MLC levels, and a lower Rho-associated kinase (ROCK) level than the control group, while LR1 pretreatment significantly declined the MLCK and MLC expression and enhanced ROCK level in the ETEC K88-challenged IPEC-J2 cells. Mechanistically, depletion of MLCK significantly declined MLC expression in IPEC-J2 challenged with ETEC K88 compared to the si NC+ETEC K88 group. On the other hand, the TER of the si MLCK+ETEC K88 group was higher and the FD4 flux in the si MLCK+ETEC K88 group was lower compared with the si NC+ETEC K88 group. In addition, depletion of MLCK significantly enhanced Claudin-1 level and declined IL-8 and TNF-α levels in IPEC-J2 pretreated with LR1 followed by challenging with ETEC K88. In conclusion, our work indicated that L. reuteri LR1 can decline inflammatory response and improve intestinal epithelial barrier function through suppressing the MLCK signal pathway in the ETEC K88-challenged IPEC-J2.

IL-23 Blockade in Anti-TNF Refractory IBD: From Mechanisms to Clinical Reality

Increasing insights into the immunopathogenesis of inflammatory bowel diseases [IBD] have led to the advent of targeted therapies that inhibit crucial mediators of the inflammatory process, thereby widening our available therapeutic armamentarium. Anti-tumour necrosis factor [anti-TNF] agents are still a mainstay of our therapeutic endeavours and the introduction of corresponding biosimilars has further widened their use. Nevertheless, only a subgroup of treated patients benefit from the initiated treatment and there is secondary non-response in the course of therapy. Initiation of subsequent therapy often poses a challenge to the treating physician, as non-response to primary anti-TNF treatment generally characterizes a patient group that is more treatment-resistant, which may be due to the immunological impregnation by prior anti-TNF exposure. At present, there is currently no guidance for the most appropriate second-line therapy after anti-TNF failure. Here, we review the efficacy of secondary biological therapy in anti-TNF-treated patients. We focus on and assess available clinical trial data of the emerging substance class of IL-23p19 inhibitors, which have demonstrated remarkable efficacy not only in anti-TNF-naïve but also refractory patients. We present molecular mechanisms that drive IL-23-mediated resistance to ongoing anti-TNF therapy and discuss the dynamic fluidity of the mucosal cytokine network in the course of therapy that perpetuates the mucosal inflammatory reaction. Translation of these findings into clinical practice might finally lead to initiation of the most appropriate therapy at the right time of the individual disease course, which would have important implications for the patient's probability of response to treatment.

Activation pathways that drive CD4+ T cells to break tolerance in autoimmune diseases. Immunol Rev 2022;307:161-190. [PMID: 35142369 PMCID: PMC9255211 DOI: 10.1111/imr.13071]

Autoimmune diseases are characterized by dysfunctional immune systems that misrecognize self as non-self and cause tissue destruction. Several cell types have been implicated in triggering and sustaining disease. Due to a strong association of major histocompatibility complex II (MHC-II) proteins with various autoimmune diseases, CD4+ T lymphocytes have been thoroughly investigated for their roles in dictating disease course. CD4+ T cell activation is a coordinated process that requires three distinct signals: Signal 1, which is mediated by antigen recognition on MHC-II molecules; Signal 2, which boosts signal 1 in a costimulatory manner; and Signal 3, which helps to differentiate the activated cells into functionally relevant subsets. These signals are disrupted during autoimmunity and prompt CD4+ T cells to break tolerance. Herein, we review our current understanding of how each of the three signals plays a role in three different autoimmune diseases and highlight the genetic polymorphisms that predispose individuals to autoimmunity. We also discuss the drawbacks of existing therapies and how they can be addressed to achieve lasting tolerance in patients.

Positioning biologics in the treatment of IBD: A practical guide - Which mechanism of action for whom?

The number of available biological therapies have doubled over the last 10 years and the arrival of novel molecules (interleukin 23p19 inhibitors) is ongoing alongside the development of small molecules. As a result of this vast landscape of treatment, positioning advanced therapies (according to clinical situation, efficacy and safety) is of paramount importance to providing personalized, appropriate IBD treatment. In this publication the recent available literature is summarized for practical integration into clinical practice including comparative efficacy data, patient and disease demographics. We refer to recent publications and expert opinion in order to facilitate the decision making process of positioning biologicals IBD treatment.

Heat stress-induced mucosal barrier dysfunction is potentially associated with gut microbiota dysbiosis in pigs

Heat stress (HS) can be detrimental to the gut health of swine. Many negative outcomes induced by HS are increasingly recognized as including modulation of intestinal microbiota. In turn, the intestinal microbiota is a unique ecosystem playing a critical role in mediating the host stress response. Therefore, we aimed to characterize gut microbiota of pigs’ exposure to short-term HS, to explore a possible link between the intestinal microbiota and HS-related changes, including serum cytokines, oxidation status, and intestinal epithelial barrier function. Our findings showed that HS led to intestinal morphological and integrity changes (villus height, serum diamine oxidase [DAO], serum D-lactate and the relative expressions of tight junction proteins), reduction of serum cytokines (interleukin [IL]-8, IL-12, interferon-gamma [IFN-γ]), and antioxidant activity (higher glutathione [GSH] and malondialdehyde [MDA] content, and lower superoxide dismutase [SOD]). Also, 16S rRNA sequencing analysis revealed that although there was no difference in microbial α-diversity, some HS-associated composition differences were revealed in the ileum and cecum, which partly led to an imbalance in the production of short-chain fatty acids including propionate acid and valerate acid. Relevance networks revealed that HS-derived changes in bacterial genera and microbial metabolites, such as Chlamydia, Lactobacillus, Succinivibrio, Bifidobacterium, Lachnoclostridium, and propionic acid, were correlated with oxidative stress, intestinal barrier dysfunction, and inflammation in pigs. Collectively, our observations suggest that intestinal damage induced by HS is probably partly related to the gut microbiota dysbiosis, though the underlying mechanism remains to be fully elucidated.

Cow Milk Extracellular Vesicle Effects on an In Vitro Model of Intestinal Inflammation

Extracellular vesicles (EVs) are lipid bilayer nano-dimensional spherical structures and act mainly as signaling mediators between cells, in particular modulating immunity and inflammation. Milk-derived EVs (mEVs) can have immunomodulatory and anti-inflammatory effects, and milk is one of the most promising food sources of EVs. In this context, this study aimed to evaluate bovine mEVs anti-inflammatory and immunomodulating effects on an in vitro co-culture (Caco-2 and THP-1) model of intestinal inflammation through gene expression evaluation with RT-qPCR and cytokine release through ELISA. After establishing a pro-inflammatory environment due to IFN-γ and LPS stimuli, CXCL8, IL1B, TNFA, IL12A, IL23A, TGFB1, NOS2, and MMP9 were significantly up-regulated in inflamed Caco-2 compared to the basal co-culture. Moreover, IL-17, IL-1β, IL-6, TNF-α release was increased in supernatants of THP-1. The mEV administration partially restored initial conditions with an effective anti-inflammatory activity. Indeed, a decrease in gene expression and protein production of most of the tested cytokines was detected, together with a significant gene expression decrease in MMP9 and the up-regulation of MUC2 and TJP1. These results showed a fundamental capability of mEVs to modulate inflammation and their potential beneficial effect on the intestinal mucosa.

Genome Editing Using CRISPR-Cas9 and Autoimmune Diseases: A Comprehensive Review

Autoimmune diseases are disorders that destruct or disrupt the body's own tissues by its own immune system. Several studies have revealed that polymorphisms of multiple genes are involved in autoimmune diseases. Meanwhile, gene therapy has become a promising approach in autoimmune diseases, and clustered regularly interspaced palindromic repeats and CRISPR-associated protein 9 (CRISPR-Cas9) has become one of the most prominent methods. It has been shown that CRISPR-Cas9 can be applied to knock out proprotein convertase subtilisin/kexin type 9 (PCSK9) or block PCSK9, resulting in lowering low-density lipoprotein cholesterol. In other studies, it can be used to treat rare diseases such as ornithine transcarbamylase (OTC) deficiency and hereditary tyrosinemia. However, few studies on the treatment of autoimmune disease using CRISPR-Cas9 have been reported so far. In this review, we highlight the current and potential use of CRISPR-Cas9 in the management of autoimmune diseases. We summarize the potential target genes for immunomodulation using CRISPR-Cas9 in autoimmune diseases including rheumatoid arthritis (RA), inflammatory bowel diseases (IBD), systemic lupus erythematosus (SLE), multiple sclerosis (MS), type 1 diabetes mellitus (DM), psoriasis, and type 1 coeliac disease. This article will give a new perspective on understanding the use of CRISPR-Cas9 in autoimmune diseases not only through animal models but also in human models. Emerging approaches to investigate the potential target genes for CRISPR-Cas9 treatment may be promising for the tailored immunomodulation of some autoimmune diseases in the near future.

A Fiber-Rich Diet and Radiation-Induced Injury in the Murine Intestinal Mucosa

Dietary fiber is considered a strong intestinal protector, but we do not know whether dietary fiber protects against the long-lasting mucosal damage caused by ionizing radiation. To evaluate whether a fiber-rich diet can ameliorate the long-lasting pathophysiological hallmarks of the irradiated mucosa, C57BL/6J mice on a fiber-rich bioprocessed oat bran diet or a fiber-free diet received 32 Gray in four fractions to the distal colorectum using a linear accelerator and continued on the diets for one, six or 18 weeks. We quantified degenerating crypts, crypt fission, cell proliferation, crypt survival, macrophage density and bacterial infiltration. Crypt loss through crypt degeneration only occurred in the irradiated mice. Initially, it was most frequent in the fiber-deprived group but declined to levels similar to the fiber-consuming group by 18 weeks. The fiber-consuming group had a fast response to irradiation, with crypt fission for growth or healing peaking already at one week post-irradiation, while crypt fission in the fiber-deprived group peaked at six weeks. A fiber-rich diet allowed for a more intense crypt cell proliferation, but the recovery of crypts was eventually lost by 18 weeks. Bacterial infiltration was a late phenomenon, evident in the fiber-deprived animals and intensified manyfold after irradiation. Bacterial infiltration also coincided with a specific pro-inflammatory serum cytokine profile. In contrast, mice on a fiber-rich diet were completely protected from irradiation-induced bacterial infiltration and exhibited a similar serum cytokine profile as sham-irradiated mice on a fiber-rich diet. Our findings provide ample evidence that dietary fiber consumption modifies the onset, timing and intensity of radiation-induced pathophysiological processes in the intestinal mucosa. However, we need more knowledge, not least from clinical studies, before this finding can be introduced to a new and refined clinical practice.

Enhanced Intestinal Barriers by Puerarin in Combination with Tryptophan

The intestinal barrier is essential for maintaining human intestinal health. The growing number of studies has shown that both puerarin and tryptophan and its metabolites have a beneficial effect on the intestinal barrier. This study aims at the combination of puerarin and tryptophan or its metabolites for improving the intestinal barrier. In our study, 40 female Sprague-Dawley rats were randomly divided into five groups (n = 8) for a 4-week experiment and dextran sodium sulfate was used to induce an intestinal barrier injury in rats. Our results showed that puerarin combined with tryptophan or its metabolites (indole-3-propionic acid, IPA) improved the intestinal barrier by enhancing the mucus layer barrier, which was mainly achieved by increasing the number of goblet cells and promoting the secretion of MUC2. Both TRPM5 and VAMP8 promoted MUC2 secretion in goblet cells through exocytosis, but their mechanisms of action are different. In our study, we found that puerarin and tryptophan showed different effects on TRPM5 and VAMP8, respectively. Puerarin enhances the expression of TRPM5, and tryptophan inhibits the expression of TRPM5; however, puerarin and tryptophan have no significant effect on the expression of VAMP8.

Exploring the Early Phase of Crohn's Disease

The development of Crohn's disease (CD) is characterized by a breakdown of homeostatic immune-bacterial communication, which takes place at the intestinal mucosa when environmental triggers impact genetically predisposed individuals. Converging lines of evidence support the hypothesis that this pathogenetic model develops through sequential, although inter-related, steps that indicate failure of mucosal defense mechanisms at various stages. In this context, immunologic phenomena that mediate the initial appearance of inflammatory lesions across the intestinal tissue may differ substantially from those that mediate and perpetuate chronic inflammatory responses. A compromise in the integrity of the epithelial barrier is among the earliest events and leads to accelerated influx of intraluminal antigens and intact microorganisms within the immunologically rich lamina propria. Inadequate clearance of invading microorganisms also may occur as a result of defects in innate immunity, preventing the timely and complete resolution of acute inflammatory responses. The final step is the development of persistent adaptive responses, which also differ between early and late Crohn's disease. Current progress in our ability to delineate single-cell transcriptomics and proteomics has allowed the discovery of cellular and molecular mechanisms that participate in each sequential step of CD development. This not only will advance our understanding of CD pathogenesis, but also facilitate the design of targeted therapeutic approaches.

Synthetic Microbiomes on the Rise-Application in Deciphering the Role of Microbes in Host Health and Disease

The intestinal microbiota conveys significant benefits to host physiology. Although multiple chronic disorders have been associated with alterations in the intestinal microbiota composition and function, it is still unclear whether these changes are a cause or a consequence. Hence, to translate microbiome research into clinical application, it is necessary to provide a proof of causality of host–microbiota interactions. This is hampered by the complexity of the gut microbiome and many confounding factors. The application of gnotobiotic animal models associated with synthetic communities allows us to address the cause–effect relationship between the host and intestinal microbiota by reducing the microbiome complexity on a manageable level. In recent years, diverse bacterial communities were assembled to analyze the role of microorganisms in infectious, inflammatory, and metabolic diseases. In this review, we outline their application and features. Furthermore, we discuss the differences between human-derived and model-specific communities. Lastly, we highlight the necessity of generating novel synthetic communities to unravel the microbial role associated with specific health outcomes and disease phenotypes. This understanding is essential for the development of novel non-invasive targeted therapeutic strategies to control and modulate intestinal microbiota in health and disease.

DOK3 maintains intestinal homeostasis by suppressing JAK2/STAT3 signaling and S100a8/9 production in neutrophils

How pathogenesis of inflammatory bowel disease (IBD) depends on the complex interplay of host genetics, microbiome and the immune system is not fully understood. Here, we showed that Downstream of Kinase 3 (DOK3), an adapter protein involved in immune signaling, confers protection of mice from dextran sodium sulfate (DSS)-induced colitis. DOK3-deficiency promotes gut microbial dysbiosis and enhanced colitis susceptibility, which can be reversed by the transfer of normal microbiota from wild-type mice. Mechanistically, DOK3 exerts its protective effect by suppressing JAK2/STAT3 signaling in colonic neutrophils to limit their S100a8/9 production, thereby maintaining gut microbial ecology and colon homeostasis. Hence, our findings reveal that the immune system and microbiome function in a feed-forward manner, whereby DOK3 maintains colonic neutrophils in a quiescent state to establish a gut microbiome essential for intestinal homeostasis and protection from IBD.

Aged Ripe Pu-erh Tea Reduced Oxidative Stress-Mediated Inflammation in Dextran Sulfate Sodium-Induced Colitis Mice by Regulating Intestinal Microbes

Ripened pu-erh tea has the biological activity of antioxidation and anti-inflammation, which inhibits the related parameters of colitis. However, the role of storage-induced changes in bioactive ingredients of ripened pu-erh tea in colitis remains unclear. In this study, 3.5% dextran sulfate sodium-induced colitis mice were treated with 10 mg/kg bw/day extracts, aged 14 years (P2006) and unaged (P2020) ripened pu-erh tea, respectively, for 1 week. We found that ripened pu-erh tea, especially P2006, inhibited the intestinal oxidative stress-mediated inflammation pathway (TLR4/MyD88/ROS/p38MAPK/NF-κB p65), upregulated the expression of intestinal tight junction proteins (Mucin-2, ZO-1, occludin), promoted M2 polarization of macrophages, and in turn, improved the intestinal immune barrier, which stemmed from the reshaping of intestinal microbiota (e.g., increased Lachnospiraceae_NK4A136_group and Akkermansia levels). Our results speculate that drinking aged ripe pu-erh tea (10 mg/kg bw/day in mice, a human equivalent dose of 7 g/60 kg bw/day) has a practical effect on alleviating and preventing the development of intestinal inflammation.

Oat β-glucan alleviates DSS-induced colitis via regulating gut microbiota metabolism in mice

Ulcerative colitis (UC) is one of the most prevalent inflammatory bowel diseases (IBD) worldwide, while oat β-glucan has been shown to suppress the progress of colitis in UC mice. However, the underlying mechanism of oat β-glucan in ameliorating colitis is unclear and the role of gut microbiota in the protective effect of oat β-glucan against colitis remains unknown. In the present study, we aim to investigate the effect of oat β-glucan on gut microbiota in colitis mice and explore the health effect related mechanism. Dextran sulfate sodium (DSS) was used to induce the colitis model in mice. The results showed that β-glucan treatment attenuated hematochezia, splenomegaly and colon shortening in colitis mice. Histological evaluation of H&E and TUNEL staining showed that β-glucan treatment suppressed DSS-induced colonic inflammatory infiltration and reduced cell apoptosis levels of colon tissues. mRNA expression levels of the pro-inflammatory factors were also significantly reduced in the β-glucan group. Moreover, β-glucan treatment increased the protein and mRNA expression levels of tight junction proteins. Analysis of gut microbiota community showed that β-glucan treatment modulated gut microbial composition and structure at the OTU level in colitis mice. Further analysis of gut microbial metabolism revealed that β-glucan treatment significantly increased acetate, propionate and butyrate concentrations, and affected microbial metabolome in colitis mice. Notably, the increased acetate and propionate concentrations could directly affect pro-inflammatory factor expression levels and tight junction protein levels. In contrast, the changes in metabolic profiles affected pro-inflammatory factor levels and thus affected tight junction protein levels. Overall, our study revealed that oat β-glucan ameliorated DSS-induced colitis in mice simultaneously through regulating gut-derived short-chain fatty acids (SCFAs) and microbial metabolic biomarkers. Our study demonstrated that oat β-glucan could be an effective nutritional intervention strategy towards targeting gut microbiota metabolism for ameliorating colitis.

Non-autophagy Role of Atg5 and NBR1 in Unconventional Secretion of IL-12 Prevents Gut Dysbiosis and Inflammation

Intestinal myeloid cells play a critical role in balancing intestinal homeostasis and inflammation. Here, we report that expression of the autophagy-related 5 [Atg5] protein in myeloid cells prevents dysbiosis and excessive intestinal inflammation by limiting IL-12 production. Mice with a selective genetic deletion of Atg5 in myeloid cells [Atg5ΔMye] showed signs of dysbiosis preceding colitis, and exhibited severe intestinal inflammation upon colitis induction that was characterised by increased IFNγ production. The exacerbated colitis was linked to excess IL-12 secretion from Atg5-deficient myeloid cells and gut dysbiosis. Restoration of the intestinal microbiota or genetic deletion of IL-12 in Atg5ΔMye mice attenuated the intestinal inflammation in Atg5ΔMye mice. Additionally, Atg5 functions to limit IL-12 secretion through modulation of late endosome [LE] acidity. Last, the autophagy cargo receptor NBR1, which accumulates in Atg5-deficient cells, played a role by delivering IL-12 to LE. In summary, Atg5 expression in intestinal myeloid cells acts as an anti-inflammatory brake to regulate IL-12, thus preventing dysbiosis and uncontrolled IFNγ-driven intestinal inflammation.

Impaired IFN-γ-dependent STAT3 Activation Is Associated With Dysregulation of Regulatory and Inflammatory Signaling in Monocytes of Ulcerative Colitis Patients

BACKGROUND

The Janus kinase/signal transducer and activator of transcription (JAK/STAT) inhibitor tofacitinib has been recently approved for the treatment of ulcerative colitis (UC) but not Crohn's disease (CD). Systematic analysis of the JAK/STAT pathway in inflammatory bowel disease is still missing. The aim of this study was to investigate JAK/STAT activation and adjacent signaling in monocytes of patients with inflammatory bowel diseases, which are key players in inflammatory responses.

METHODS

Blood samples of active UC (n = 28) and CD patients (n = 28) and healthy controls (n = 22) were collected for primary monocyte investigation. STAT phosphorylation (pSTAT), cytokine secretion, and surface marker expression ± prior tofacitinib blockade in addition to Th-17 and regulatory T cell induction in cocultures were analyzed upon interferon (IFN)-γ timulation.

RESULTS

Baseline frequencies of pSTAT1+ and pSTAT3+ monocytes were significantly higher in UC, whereas IFN-γ-associated crosstalk induction of pSTAT3+ monocytes was missing in UC-derived monocytes compared with controls and CD. This coincided with decreased interleukin (IL)-10 and cluster of differentiation (CD)39 levels, diminished regulatory T cell (Treg) induction, and increased IL-12 and IL-23 secretion compared with controls, which was not observed in CD monocytes. Tofacitinib induced stronger inhibition of inflammatory cytokine release (IL-6, TNFα, IL-12, IL-23) in UC compared with CD monocytes.

CONCLUSIONS

In UC monocytes, IFN-γ-associated activation of the JAK/STAT pathway is impaired with an imbalance between STAT1 and STAT3, coinciding with stronger induction of inflammatory monocytes by IFN-γ compared with controls or CD. The fact that tofacitinib had stronger regulatory impact on UC than on CD monocytes further underlines a stronger inflammatory involvement of the JAK/STAT pathway in UC pathogenesis, which might result from missing STAT3 activation to counteract STAT1-induced inflammation.

Pathogenesis and Function of Interleukin-35 in Rheumatoid Arthritis

It is well known that RA (Rheumatoid arthritis) is an autoimmune disease characterized by multiple and symmetric arthropathy. The main pathological features of RA are synovial hyperplasia, angiogenesis, pannus formation, inflammatory cell infiltration, articular cartilage, bone destruction, and ultimately joint dysfunction, even deformity. IL-35 (Interleukin-35) is a new member of the IL-12 (Interleukin-12) family, which is an immunosuppressive and anti-inflammatory cytokine secreted mainly by Treg (T regulatory cells). There is evidence suggested that IL-35 can attenuate the progression of RA through influencing the immune and pathological process. It suggests that IL-35 played an important role in the pathogenesis of RA, and can be used as a potential target for the future treatment of RA. This review summarizes the recent advances of IL-35 in the pathological roles and the therapeutic potential roles in RA.

Anti-IL-23 exerted protective effects on cerebral ischemia-reperfusion injury through JAK2/STAT3 signaling pathway

Ischemia-reperfusion frequently occurs in ischemic cerebral vascular disease, during which the inflammatory signaling plays essential roles. The aim of this study was to discover the efficacy of the antibody to a key immune cytokine IL-23 (anti-IL-23) for the therapy of cerebral ischemia-reperfusion injury. We established the cerebral ischemia-reperfusion injury model by middle cerebral artery occlusion (MCAO). Anti-IL-23 injection attenuated lesions indicated by histology study. RT-PCR and Western blot were employed to detect the mRNA and protein expression of JAK2 and STAT3 after anti-IL-23 treatment. ELISA was utilized to measure the levels of MDA (malondialdehyde) and superoxide dismutase (SOD). Moreover, curcumin and IL-6 were implicated in the endogenous intervention of IL-23 signaling in vivo. Our data demonstrated that the treatment of anti-IL-23 might transcriptionally activate the classic immune pathway in the brain. Anti-IL-23 augmented phosphorylation levels of both JAK2 and STAT3, suggesting the amplification signaling of JAK/STAT after exogenous IL-23 intervention. Anti-IL-23 reduced ROS molecules of STAT downstream in the serum and brain. It also alleviated the injury by bringing down levels of MDA and SOD in the serum. JAK2 inhibitor could abolish the effect of anti-IL-23 whereas JAK3 ameliorated the injury. The combination of anti-IL-23 and JAK3i could reduce infarct volume more effectively. In summary, this study indicated that anti-IL-23 had protective effects against cerebral ischemia-reperfusion injury by targeting the immune specific JAK2-STAT3 in JAK/STAT pathway.

siRNA-based identification of IBD-related targets in human monocyte-derived dendritic cells

Inflammatory bowel disease (IBD) is thought to be caused by an aberrant host response to the commensal enteric flora in genetically susceptible individuals. Dendritic cells (DCs) play a key role in the regulation of this response as they sample gut commensals. In healthy individuals DCs actively contribute to tolerance upon recognition of these resident bacteria, whereas in individuals with IBD, DCs will initiate an inflammatory response. To mimic the disease response in vitro, human monocyte-derived DCs were matured with E. coli causing the cells to produce high levels of the pro-inflammatory cytokine IL-12/IL-23p40 (p40) and low levels of the anti-inflammatory cytokine IL-10. A siRNA-based screening assay was developed and screened to identify potential therapeutic targets that shift this balance towards an immunosuppressive state with lower levels of p40 and higher levels of IL-10. The screening assay was optimized and quality controlled using non-targeting controls and positive control siRNAs targeting IL12B and TLR4 transcripts. In the primary screen, smartpool siRNAs were screened for reduction in p40 expression, induction of IL-10 levels, or increase in IL-10:p40 ratios without affecting cell viability. All potential targets were taken forward into a confirmation screen in a different DC donor in which four individual siRNAs per target were screened. At least two siRNAs per target should have an effect to be considered a valid target. This screen resulted in a concise list of ten genes, of which their role in DC maturation is currently being investigated.

Precision Medicine in Inflammatory Bowel Diseases

During the last decades, a better understanding of the mechanisms sustaining the pathogenic process in inflammatory bowel diseases (IBD) has contributed to expand the therapeutic armamentarium for patients with these disorders. Alongside with traditional therapies, monoclonal antibodies against tumor necrosis factor-α, the interleukin (IL)-12/IL-23 p40 subunit and the α4β7 integrin, and tofacitinib, a small molecule inhibiting intracellular pathways downstream to cytokine receptors, have entered into the clinic. However, these drugs are not effective in all patients and some responders can lose response over time. Such a therapeutic failure is, at least in part, dependent on the fact that, in IBD, the tissue damage is driven by simultaneous activation of multiple and distinct immune-inflammatory signals and the detrimental mucosal immune response changes over time even in the same patient. Therefore, personalized approaches aimed at identifying which patient should be treated with a specific drug at a precise time point are worth pursuing. A such approach has the advantage to improve efficacy of the drug and limit adverse reactions, thereby improving quality of the life of the patients and reducing costs. In this review, we summarize all the available evidence about the possible role of precision medicine in IBD.

Role and Mechanism of Gut Microbiota in Human Disease

The human gut microbiome is a huge microbial community that plays an irreplaceable role in human life. With the further development of research, the influence of intestinal flora on human diseases has been gradually excavated. Gut microbiota (GM) dysbiosis has adverse health effects on the human body that will lead to a variety of chronic diseases. The underlying mechanisms of GM on human diseases are incredibly complicated. This review focuses on the regulation and mechanism of GM on neurodegenerative diseases, cardiovascular diseases, metabolic diseases and gastrointestinal diseases, thus providing a potential target for the prevention and treatment of disease.

Interferons at the crossroad of cell death pathways during gastrointestinal inflammation and infection

Interferons (IFNs) are pleiotropic immune-modulatory cytokines that are well known for their essential role in host defense against viruses, bacteria, and other pathogenic microorganisms. They can exert both, protective or destructive functions depending on the microorganism, the targeted tissue and the cellular context. Interferon signaling results in the induction of IFN-stimulated genes (ISGs) influencing different cellular pathways including direct anti-viral/anti-bacterial response, immune-modulation or cell death. Multiple pathways leading to host cell death have been described, and it is becoming clear that depending on the cellular context, IFN-induced cell death can be beneficial for both: host and pathogen. Accordingly, activation or repression of corresponding signaling mechanisms occurs during various types of infection but is also an important pathway for gastrointestinal inflammation and tissue damage. In this review, we summarize the role of interferons at the crossroad of various cell death pathways in the gut during inflammation and infection.

Canthin-6-one ameliorates TNBS-induced colitis in rats by modulating inflammation and oxidative stress. An in vivo and in silico approach

Canthin-6-one (Cant) is an indole alkaloid found in several botanical drugs used as medicines, reported to be gastroprotective, anti-inflammatory, anti-microbial, anti-diarrheal and anti-proliferative. We aimed to explore Cant in the management of colitis using a trinitrobenzenesulfonic acid (TNBS)-induced rat model. Cant (1, 5 and 25 mg/kg) was administered by oral gavage to Wistar rats followed by induction of colitis with TNBS. Macroscopic and histopathological scores, myeloperoxidase (MPO), malondialdehyde (MDA) and reduced glutathione (GSH) were assessed in colon tissues. Pro- (TNF-α, IL-1β and IL-12p70) and anti-inflammatory (IL-10) cytokines, and vascular endothelial growth factor (VEGF) were also quantified. Mitogen-activated protein kinase 14 (MAPK14) and Toll-like receptor-8 (TLR8), as putative targets, were considered through in silico analysis. Cant (5 and 25 mg/kg) reduced macroscopic and histological colon damage scores in TNBS-treated rats. MPO and MDA were reduced by up to 61.69% and 92.45%, respectively, compared to TNBS-treated rats alone. Glutathione concentration was reduced in rats administered with TNBS alone (50.00% of sham group) but restored to 72.73% (of sham group) with Cant treatment. TNF-α, IL-1β, IL-12p70 and VEGF were reduced, and anti-inflammatory IL-10 was increased following Cant administration compared to rats administered TNBS alone. Docking ligation results for MAPK14 (p38α) and TLR8 with Cant, confirmed that these proteins are feasible putative targets. Cant has an anti-inflammatory effect in the intestine by down-regulating molecular immune mediators and decreasing oxidative stress. Therefore, Cant could have therapeutic potential for the treatment of inflammatory bowel disease and related syndromes.

Act Locally, Act Globally-Microbiota, Barriers, and Cytokines in Atherosclerosis

Atherosclerosis is a lipid-driven chronic inflammatory disease that is characterized by the formation and progressive growth of atherosclerotic plaques in the wall of arteries. Atherosclerosis is a major predisposing factor for stroke and heart attack. Various immune-mediated mechanisms are implicated in the disease initiation and progression. Cytokines are key mediators of the crosstalk between innate and adaptive immune cells as well as non-hematopoietic cells in the aortic wall and are emerging players in the regulation of atherosclerosis. Progression of atherosclerosis is always associated with increased local and systemic levels of pro-inflammatory cytokines. The role of cytokines within atherosclerotic plaque has been extensively investigated; however, the cell-specific role of cytokine signaling, particularly the role of cytokines in the regulation of barrier tissues tightly associated with microbiota in the context of cardiovascular diseases has only recently come to light. Here, we summarize the knowledge about the function of cytokines at mucosal barriers and the interplay between cytokines, barriers, and microbiota and discuss their known and potential implications for atherosclerosis development.

Select animal models of colitis and their value in predicting clinical efficacy of biological therapies in ulcerative colitis

Introduction: Advancing new therapies from discovery to development usually requires proof-of-concept in animal models to justify the costs of continuing the program. While animal models are useful for understanding the mechanism of action (MOA) of a target, limitations of many published colitis models restrict their value to predict clinical efficacy.Areas covered: The authors focused their literature search on published studies of chronic animal models used to evaluate the pre-clinical efficacy of therapeutic molecules subsequently evaluated in clinical trials for UC. The UC therapies evaluated were anti-α4β7, anti-IL13, anti-IL12p40, and anti-IL23p19. The models of chronic colitis evaluating these molecules were: mdra1a-/-, chronic dextran sulfate sodium (DSS), chronic 2,4,6-trinitrobenzene sulfonic acid (TNBS), and the T cell transfer model.Expert opinion: While some models provide insight into target MOA in UC, none is consistently superior in predicting efficacy. Evaluation of multiple models, with varying mechanisms of colitis induction, is needed to understand potential drug efficacy. Additional models of greater complexity, reflecting the disease chronicity/heterogeneity seen in humans, are needed. Although helpful in prioritizing targets, animal models alone will likely not improve outcomes of UC clinical trials. Transformational changes to clinical efficacy will likely only occur when precision medicine approaches are employed.

Immunology of IL-12: An update on functional activities and implications for disease

As its first identified member, Interleukin-12 (IL-12) named a whole family of cytokines. In response to pathogens, the heterodimeric protein, consisting of the two subunits p35 and p40, is secreted by phagocytic cells. Binding of IL-12 to the IL-12 receptor (IL-12R) on T and natural killer (NK) cells leads to signaling via signal transducer and activator of transcription 4 (STAT4) and subsequent interferon gamma (IFN-γ) production and secretion. Signaling downstream of IFN-γ includes activation of T-box transcription factor TBX21 (Tbet) and induces pro-inflammatory functions of T helper 1 (TH1) cells, thereby linking innate and adaptive immune responses. Initial views on the role of IL-12 and clinical efforts to translate them into therapeutic approaches had to be re-interpreted following the discovery of other members of the IL-12 family, such as IL-23, sharing a subunit with IL-12. However, the importance of IL-12 with regard to immune processes in the context of infection and (auto-) inflammation is still beyond doubt. In this review, we will provide an update on functional activities of IL-12 and their implications for disease. We will begin with a summary on structure and function of the cytokine itself as well as its receptor and outline the signal transduction and the transcriptional regulation of IL-12 secretion. In the second part of the review, we will depict the involvement of IL-12 in immune-mediated diseases and relevant experimental disease models, while also providing an outlook on potential translational approaches.

Beta-1 blocker reduces inflammation and preserves intestinal barrier function after open abdominal surgery

BACKGROUND

Open abdominal surgery is frequently related to excessive inflammation and a compromised intestinal barrier, leading to poor clinical outcomes. The administration of beta-1 blocker has been shown to effectively reduce inflammation and preserve intestinal barrier function in patients with sepsis, shock, or other critical illnesses. The underlying mechanism of these effects may be associated with the autonomic nervous system's activation via cholecystokinin receptors. This study aimed to investigate the effect of beta-1 blocker on systemic and local inflammatory responses and the intestinal barrier function in the context of open abdominal surgery.

METHODS

A rat model of open abdominal surgery was induced through peritoneal air exposure for 3 hours and treated via gavage with the beta-1 blocker, metoprolol, or saline. Cholecystokinin-receptor antagonists were administered before the metoprolol treatment. Peritoneal lavage fluid, serum, and tissues were collected 24 hours after surgery to determine systemic and local inflammation and intestinal integrity.

RESULTS

The intervention with metoprolol significantly reduced serum tumor necrosis factor-alpha and interleukin-6 (P < .05) and peritoneal interleukin-6 (P < .01) compared with those of animals treated with saline. The intestinal myeloperoxidase indicating the influx of neutrophils was also significantly prevented by the administration of metoprolol (P < .05). Above all, this intervention resulted in a significant decrease in serum D-lactate and intestinal fatty acid-binding protein, intestinal permeability, bacterial translocation, and Chiu's score for intestinal mucosa injury (P < .05). However, the anti-inflammatory and intestinal integrity protective effects of metoprolol were prevented by the blockage of cholecystokinin receptors (P < .05).

CONCLUSION

Our data indicate that beta-1 blocker reduces systemic and local inflammatory responses and preserves intestinal barrier function after open abdominal surgery through a mechanism that depends on cholecystokinin receptors. Clinically, these findings imply that perioperative intervention with a beta-1 blocker may be an effective new therapy to enhance recovery after open abdominal surgery.

TL1A primed dendritic cells activation exacerbated chronic murine colitis

AIMS

Tumor necrosis factor-like ligand 1A (TL1A) has been proved to activate adaptive immunity in inflammatory bowel disease (IBD). However, its role in the regulation of intestinal dendritic cells (DCs) has not been fully characterized. This study aims to investigate the modulation of TL1A in DCs activation in murine colitis.

MATERIALS AND METHODS

Myeloid TL1A-Transgenic C57BL/6 mice and wild-type (WT) mice were administrated with dextran sulfate sodium (DSS) to explore the effects of TL1A in murine colitis. Bone marrow-derived DCs (BMDCs) were isolated to detect the ability of antigen phagocytosis and presentation. The expression of nuclear factor-κB (NF-κB) pathway and chemokines receptors (CCRs) was assessed by real-time PCR and Western blot.

KEY FINDINGS

Myeloid cells with constitutive TL1A expression developed worsened murine colitis with exacerbated TH1/TH17 cytokine responses. Intestinal DCs from TL1A transgenic mice expressed high levels of costimulatory molecules (CD80 and CD86) with increased pro-inflammatory cytokines of IL-1β, TNF-α and IL-12/23 p40. Mechanistic studies showed that TL1A enhanced the phagocytotic ability of BMDCs. Moreover, TL1A enhanced the capacity of antigen process and presentation in BMDCs. Besides, TL1A induced the phosphorylation of NF-κB(p65) and IκBα. Meanwhile, higher expression of CCR2, CCR5, CCR7, and CX3CR1 was observed both in vivo and in vitro.

SIGNIFICANCE

TL1A exacerbated DSS-induced chronic experimental colitis, probably through activation and migration of dendritic cells, and therefore increasing the secretion of pro-inflammatory cytokines.

High Smad7 in the early post-operative recurrence of Crohn's disease

Background

In Crohn’s disease (CD), one of the major inflammatory bowel disease (IBD) in human beings, there is over-expression of Smad7, an intracellular inhibitor of the suppressive cytokine TGF-β1. The aim of this study was to assess whether Smad7 over-expression occurs in the early and/or late phases of CD.

Methods

Mucosal samples were taken from the neo-terminal ileum of CD patients undergoing ileocolonic resection, with or without (early CD) post-operative endoscopic recurrence, and terminal ileum of CD patients with long-standing disease undergoing intestinal resection (late CD). Smad7 was examined by immunohistochemistry and cytokine expression was analysed by flow-cytometry.

Results

Before the appearance of endoscopic lesions, the mucosa of the neo-terminal ileum contained high number of Smad7-expressing cells in both the epithelial and lamina propria compartments. Transition from this stage to endoscopic recurrence was marked by persistence of high number of Smad7-positive cells, which reduced significantly in the late stages of the disease, where Smad7 expression remained, however, greater than that seen in normal controls. In samples with early lesions, Smad7 expression positively correlated with the number of interferon-γ-secreting cells.

Conclusions

Smad7 induction is an early event in the inflammatory sequence occurring in CD, thus suggesting that knockdown of Smad7 can help prevent post-operative recurrence.

FADD and Caspase-8 Regulate Gut Homeostasis and Inflammation by Controlling MLKL- and GSDMD-Mediated Death of Intestinal Epithelial Cells

Pathways controlling intestinal epithelial cell (IEC) death regulate gut immune homeostasis and contribute to the pathogenesis of inflammatory bowel diseases. Here, we show that caspase-8 and its adapter FADD act in IECs to regulate intestinal inflammation downstream of Z-DNA binding protein 1 (ZBP1)- and tumor necrosis factor receptor-1 (TNFR1)-mediated receptor interacting protein kinase 1 (RIPK1) and RIPK3 signaling. Mice with IEC-specific FADD or caspase-8 deficiency developed colitis dependent on mixed lineage kinase-like (MLKL)-mediated epithelial cell necroptosis. However, MLKL deficiency fully prevented ileitis caused by epithelial caspase-8 ablation, but only partially ameliorated ileitis in mice lacking FADD in IECs. Our genetic studies revealed that caspase-8 and gasdermin-D (GSDMD) were both required for the development of MLKL-independent ileitis in mice with epithelial FADD deficiency. Therefore, FADD prevents intestinal inflammation downstream of ZBP1 and TNFR1 by inhibiting both MLKL-induced necroptosis and caspase-8-GSDMD-dependent pyroptosis-like death of epithelial cells.

CRISPR/Cas9 gene editing: A new therapeutic approach in the treatment of infection and autoimmunity

CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated protein9) may be viewed as an adaptive bacterial immune system. When a virus infects a bacterium, a fragment of the virus genome is inserted into the CRISPR sequence of the bacterial genome as a memory. When the bacterium becomes infected again with the same virus, an RNA molecule that is a transcript of the memory sequence, directs Cas9, an endonuclease, to the complementary region of the virus genome, and Cas9 disables the virus by a double-strand break. In recent years, studies have shown that by designing synthetic RNA molecules and delivering them along with Cas9 into eukaryotic cells, different regions of the cell's genome can be targeted and manipulated. These findings have drawn much attention to this new technology and it has been shown that CRISPR/Cas9 gene editing can be used to treat some human diseases. These include infectious diseases and autoimmune diseases. In this review article, in addition to a brief overview of the biology of the CRISPR/Cas9 system, we collected the most recent findings on the applications of CRISPR/Cas9 technology for better investigation of the pathogenesis and treatment of viral infections (human immunodeficiency virus infection, hepatitis virus infections, and onco-virus infections), non-viral infections (parasitic, fungal, and bacterial infections), and autoimmune diseases.

c-FLIP is crucial for IL-7/IL-15-dependent NKp46+ ILC development and protection from intestinal inflammation in mice

NKp46⁺ innate lymphoid cells (ILC) modulate tissue homeostasis and anti-microbial immune responses. ILC development and function are regulated by cytokines such as Interleukin (IL)-7 and IL-15. However, the ILC-intrinsic pathways translating cytokine signals into developmental programs are largely unknown. Here we show that the anti-apoptotic molecule cellular FLICE-like inhibitory protein (c-FLIP) is crucial for the generation of IL-7/IL-15-dependent NKp46⁺ ILC1, including conventional natural killer (cNK) cells, and ILC3. Cytokine-induced phosphorylation of signal transducer and activator of transcription 5 (STAT5) precedes up-regulation of c-FLIP, which protects developing NKp46⁺ ILC from TNF-induced apoptosis. NKp46⁺ ILC-specific inactivation of c-FLIP leads to the loss of all IL-7/IL-15-dependent NKp46⁺ ILC, thereby inducing early-onset chronic colitis and subsequently microbial dysbiosis; meanwhile, the depletion of cNK, but not NKp46⁺ ILC1/3, aggravates experimental colitis. In summary, our data demonstrate a non-redundant function of c-FLIP for the generation of NKp46⁺ ILC, which protect T/B lymphocyte-sufficient mice from intestinal inflammation.

Oral Administration of Heat-Treated Lactobacilli Modifies the Murine Microbiome and Reduces Citrobacter Induced Colitis

Significant evidence supports a relationship between the gut microbiome, inflammation, host response, and health, including the finding that a number of disorders are associated with disruption of the microbiome. In these disorders, a number of dietary interventions (including prebiotics, live probiotics, or heat-killed microbes) have been proposed to be curative or preventative agents. The use of heat-killed microbes has a number of benefits over living organisms, including reduced infection risk in vulnerable individuals, extended shelf life and the potential for use in combination with antimicrobial agents. We previously reported that murine chow supplemented with 5% ADR-159, a heat-treated fermentate generated by two Lactobacillus strains, altered both behavior and the microbiome of male mice. Now we show that ADR-159 fed female mice also display a similar microbiome shift as determined by 16S rDNA analysis. In particular, we observed a reduction of levels of Turicibacter and Clostridium sensu stricto. These subtle changes in the bacterial component of the microbiome were mirrored by changes in the virome. Extended consumption of the ADR-159 diet had no negative effect on general health and lipocalin 2 levels (LCN2; a proxy for inflammation), but we observed increased IL-17f and decreased IL-12α expression in the colon and decreased short chain fatty acid levels in the ADR-159 fed animals. Four weeks into the diet, half of the animals were dosed with Citrobacter to determine the effect of ADR-159 on infection and on pathogen induced colitis. Overall, our results suggest that while the ADR-159 diet does not prevent Citrobacter infection, it had an effect on Citrobacter-induced inflammation. In contrast to animals fed standard chow, ADR-159 fed animals did not show a reduction of small intestine length and increase of colon crypt depth, which occurred in control mice. These microbiological, histological, and immunological results provide evidence to support the impact of heat-treated microorganisms and their metabolites on the murine microbiome and health.

Signalling, sorting and scaffolding adaptors for Toll-like receptors

Toll-like receptors (TLRs) are danger-sensing receptors that typically propagate self-limiting inflammatory responses, but can unleash uncontrolled inflammation in non-homeostatic or disease settings. Activation of TLRs by pathogen- and/or host-derived stimuli triggers a range of signalling and transcriptional pathways to programme inflammatory and anti-microbial responses, including the production of a suite of inflammatory cytokines and other mediators. Multiple sorting and signalling adaptors are recruited to receptor complexes on the plasma membrane or endosomes where they act as scaffolds for downstream signalling kinases and effectors at these sites. So far, seven proximal TLR adaptors have been identified: MyD88, MAL, TRIF (also known as TICAM1), TRAM (TICAM2), SARM (SARM1), BCAP (PIK3AP1) and SCIMP. Most adaptors tether directly to TLRs through homotypic Toll/interleukin-1 receptor domain (TIR)-TIR interactions, whereas SCIMP binds to TLRs through an atypical TIR-non-TIR interaction. In this Review, we highlight the key roles for these adaptors in TLR signalling, scaffolding and receptor sorting and discuss how the adaptors thereby direct the differential outcomes of TLR-mediated responses. We further summarise TLR adaptor regulation and function, and make note of human diseases that might be associated with mutations in these adaptors.

A Role for IL-12 in IBD after All?

The interplay between intestinal epithelial barrier function, the intestinal microbiota, and cytokine signaling in the pathogenesis of inflammatory bowel disease is not completely understood. In this issue of Immunity, Eftychi et al. examined the cell types and cytokines that drive colitis in mice with an intestinal epithelial barrier defect and uncovered a surprising role for IL-12 in initiation of disease.