The Innate Immune System in the Gastrointestinal Tract: Role of Intraepithelial Lymphocytes and Lamina Propria Innate Lymphoid Cells in Intestinal Inflammation

A comprehensive immunobiology review of IBD: With a specific glance to Th22 lymphocytes development, biology, function, and role in IBD

The two primary forms of inflammatory disorders of the small intestine andcolon that make up inflammatory bowel disease (IBD) are ulcerative colitis (UC) and Crohn's disease (CD). While ulcerative colitis primarily affects the colon and the rectum, CD affects the small and large intestines, as well as the esophagus,mouth, anus, andstomach. Although the etiology of IBD is not completely clear, and there are many unknowns about it, the development, progression, and recurrence of IBD are significantly influenced by the activity of immune system cells, particularly lymphocytes, given that the disease is primarily caused by the immune system stimulation and activation against gastrointestinal (GI) tract components due to the inflammation caused by environmental factors such as viral or bacterial infections, etc. in genetically predisposed individuals. Maintaining homeostasis and the integrity of the mucosal barrier are critical in stopping the development of IBD. Specific immune system cells and the quantity of secretory mucus and microbiome are vital in maintaining this stability. Th22 cells are helper T lymphocyte subtypes that are particularly important for maintaining the integrity and equilibrium of the mucosal barrier. This review discusses the most recent research on these cells' biology, function, and evolution and their involvement in IBD.

The emerging role of oxidative stress in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic immune-mediated condition that affects the digestive system and includes Crohn's disease (CD) and ulcerative colitis (UC). Although the exact etiology of IBD remains uncertain, dysfunctional immunoregulation of the gut is believed to be the main culprit. Amongst the immunoregulatory factors, reactive oxygen species (ROS) and reactive nitrogen species (RNS), components of the oxidative stress event, are produced at abnormally high levels in IBD. Their destructive effects may contribute to the disease's initiation and propagation, as they damage the gut lining and activate inflammatory signaling pathways, further exacerbating the inflammation. Oxidative stress markers, such as malondialdehyde (MDA), 8-hydroxy-2'-deoxyguanosine (8-OHdG), and serum-free thiols (R-SH), can be measured in the blood and stool of patients with IBD. These markers are elevated in patients with IBD, and their levels correlate with the severity of the disease. Thus, oxidative stress markers can be used not only in IBD diagnosis but also in monitoring the response to treatment. It can also be targeted in IBD treatment through the use of antioxidants, including vitamin C, vitamin E, glutathione, and N-acetylcysteine. In this review, we summarize the role of oxidative stress in the pathophysiology of IBD, its diagnostic targets, and the potential application of antioxidant therapies to manage and treat IBD.

Preclinical pharmacokinetics-related pharmacological effects of orally administered polysaccharides from traditional Chinese medicines: A review

Polysaccharides (TCMPs) derived from traditional Chinese medicines (TCMs), such as Ganoderma lucidum, Astragalus membranaceus, Lycium barbarum, and Panax ginseng, are considered to be the main active constituents in TCMs. However, the significant pharmacological effects of orally administered TCMPs do not align well with their poor pharmacokinetics. This article aims to review the literature published mainly from 2010 to 2022, focusing on the relationship between pharmacokinetics and pharmacological effects. It has been found that unabsorbed TCMPs can exert local pharmacological effects in the gut, including anti-inflammation, anti-oxidation, regulation of intestinal flora, modulation of intestinal immunity, and maintenance of intestinal barrier integrity. Unabsorbed TCMPs can also produce systemic pharmacological effects, such as anti-tumor activity and immune system modulation, by regulating intestinal flora and immunity. Conversely, some TCMPs can be absorbed and distributed to various tissues, especially the liver, where they exhibit tissue-protecting effects against inflammation and oxidative stress-induced damage and improve glucose and lipid metabolism. In future studies, it is important to improve quality control and experimental design. Furthermore, research on enhancing the oral bioavailability of TCMPs, exploring the activity of TCMP metabolites, investigating pharmacokinetic interactions between TCMPs and oral drugs, and developing oral drug delivery systems using TCMPs holds great significance.

Single cell transcriptome analyses reveal the roles of B cells in fructose-induced hypertension

Rationale

While the immune system plays a crucial role in the development of hypertension, the specific contributions of distinct immune cell populations remain incompletely understood. The emergence of single-cell RNA-sequencing (scRNA-seq) technology enables us to analyze the transcriptomes of individual immune cells and to assess the significance of each immune cell type in hypertension development.

Objective

We aimed to investigate the hypothesis that B cells play a crucial role in the development of fructose-induced hypertension.

Methods and Results

Eight-week-old Dahl salt-sensitive (SS) male rats were divided into two groups and given either tap water (TW) or a 20% fructose solution (HFS) for 4 weeks. Systolic blood pressure was measured using the tail-cuff method. ScRNA-seq analysis was performed on lamina propria cells (LPs) and peripheral blood mononuclear cells (PBMCs) obtained from SS rats subjected to either TW or HFS. The HFS treatment induced hypertension in the SS rats. The analysis revealed 27 clusters in LPs and 28 clusters in PBMCs, allowing for the identification and characterization of various immune cell types within each cluster. Specifically, B cells and follicular helper T (Tfh) cells were prominent in LPs, while B cells and M1 macrophages dominated PBMCs in the HFS group. Moreover, the HFS treatment triggered an increase in the number of B cells in both LPs and PBMCs, accompanied by activation of the interferon pathway.

Conclusions

The significant involvement of B cells in intestinal and PBMC responses indicates their pivotal contribution to the development of hypertension. This finding suggests that targeting B cells could be a potential strategy to mitigate high blood pressure in fructose-induced hypertension. Moreover, the simultaneous increase in follicular B cells and Tfh cells in LPs, along with the upregulation of interferon pathway genes in B cells, underscores a potential autoimmune factor contributing to the pathogenesis of fructose-induced hypertension in the intestine.

Understanding the potential causes of gastrointestinal dysfunctions in multiple system atrophy

Multiple system atrophy (MSA) is a rare, progressive neurodegenerative disorder characterised by autonomic, pyramidal, parkinsonian and/or cerebellar dysfunction. Autonomic symptoms of MSA include deficits associated with the gastrointestinal (GI) system, such as difficulty swallowing, abdominal pain and bloating, nausea, delayed gastric emptying, and constipation. To date, studies assessing GI dysfunctions in MSA have primarily focused on alterations of the gut microbiome, however growing evidence indicates other structural components of the GI tract, such as the enteric nervous system, the intestinal barrier, GI hormones, and the GI-driven immune response may contribute to MSA-related GI symptoms. Here, we provide an in-depth exploration of the physiological, structural, and immunological changes theorised to underpin GI dysfunction in MSA patients and highlight areas for future research in order to identify more suitable pharmaceutical treatments for GI symptoms in patients with MSA.

Reduced Intake of Dietary Tryptophan Improves Beneficial Action of Budesonide in Patients with Lymphocytic Colitis and Mood Disorders

Lymphocytic colitis (LC) is a gastrointestinal (GI) tract disease with poorly known pathogenesis, but some environmental and lifestyle factors, including certain dietary components, may play a role. Tryptophan is an essential amino acid, which plays important structural and functional roles as a component of many proteins. It is important in the development and maintenance of the body, in which it is metabolized in two main pathways: kynurenine (KYN) and serotonin. In this work, we explored the effect of reducing of TRP in the diet of patients with LC with mood disorders. We enrolled 40 LC patients who had a normal diet, 40 LC patients with the 8-week diet with TRP content reduced by 25% and 40 controls. All LC patients received budesonide at 9 mg per day, and the severity of their GI symptoms was evaluated by the Gastrointestinal Symptoms Rating Scale. Mood disorders were evaluated by the Hamilton Anxiety Rating Scale (HAM-A) and the Hamilton Depression Rating Scale (HAM-D). The concentration of TRP and its metabolites, 5-hydroxyindoleacetic acid (5-HIAA), kynurenine (KYN), kynurenic acid (KYNA) and quinolinic acid (QA), in urine were determined. Budesonide improved the GI and mental states of LC patients, and the diet with reduced TRP content further amended these symptoms. Dietary intervention decreased the concentration of 5-HIAA by about 50% (3.4 vs. 6.3) and QA by about 45% (3.97 vs. 7.20). These changes were correlated with a significant improvement in the profitable action of budesonide on gastrointestinal and mental health of LC patients as they displayed significantly lower GSRS, HAM-A and HAM-B scores after than before the intervention—10.5 vs. 32, 11.0 vs. 21 and 12 vs. 18, respectively. In conclusion, a reduction in TRP intake in diet may improve GI and mental symptoms in LC patients treated with budesonide and these changes may be mediated by the products of TRP metabolism.

Immunity orchestrates a bridge in gut-brain axis of neurodegenerative diseases

Neurodegenerative diseases, in particular for Alzheimer's disease (AD), Parkinson's disease (PD) and Multiple sclerosis (MS), are a category of diseases with progressive loss of neuronal structure or function (encompassing neuronal death) leading to neuronal dysfunction, whereas the underlying pathogenesis remains to be clarified. As the microbiological ecosystem of the intestinal microbiome serves as the second genome of the human body, it is strongly implicated as an essential element in the initiation and/or progression of neurodegenerative diseases. Nevertheless, the precise underlying principles of how the intestinal microflora impact on neurodegenerative diseases via gut-brain axis by modulating the immune function are still poorly characterized. Consequently, an overview of initiating the development of neurodegenerative diseases and the contribution of intestinal microflora on immune function is discussed in this review.

Enterocyte-specific deletion of metal transporter Zip14 (Slc39a14) alters intestinal homeostasis through epigenetic mechanisms

Zinc has anti-inflammatory properties using mechanisms that are unclear. Zip14 (Slc39a14) is a zinc transporter induced by proinflammatory stimuli and is highly expressed at the basolateral membrane of intestinal epithelial cells (IECs). Enterocyte-specific Zip14 ablation (Zip14ΔIEC) in mice was developed to study the functions of this transporter in enterocytes. This gene deletion led to increased intestinal permeability, increased IL-6 and IFNγ expression, mild endotoxemia, and intestinal dysbiosis. RNA sequencing was used for transcriptome profiling. These analyses revealed differential expression of specific intestinal proinflammatory and tight junction (TJ) genes. Binding of transcription factors, including NF-κβ, STAT3, and CDX2, to appropriate promoter sites of these genes supports the differential expression shown with chromatin immunoprecipitation assays. Total histone deacetylase (HDAC), and specifically HDAC3, activities were markedly reduced with Zip14 ablation. Intestinal organoids derived from ΔIEC mice display TJ and cytokine gene dysregulation compared with control mice. Differential expression of specific genes was reversed with zinc supplementation of the organoids. We conclude that zinc-dependent HDAC enzymes acquire zinc ions via Zip14-mediated transport and that intestinal integrity is controlled in part through epigenetic modifications.NEW & NOTEWORTHY We show that enterocyte-specific ablation of zinc transporter Zip14 (Slc39a14) results in selective dysbiosis and differential expression of tight junction proteins, claudin 1 and 2, and specific cytokines associated with intestinal inflammation. HDAC activity and zinc uptake are reduced with Zip14 ablation. Using intestinal organoids, the expression defects of claudin 1 and 2 are resolved through zinc supplementation. These novel results suggest that zinc, an essential micronutrient, influences gene expression through epigenetic mechanisms.

Molecular Mechanisms of Hyperoxia-Induced Neonatal Intestinal Injury

Oxygen therapy is important for newborns. However, hyperoxia can cause intestinal inflammation and injury. Hyperoxia-induced oxidative stress is mediated by multiple molecular factors and leads to intestinal damage. Histological changes include ileal mucosal thickness, intestinal barrier damage, and fewer Paneth cells, goblet cells, and villi, effects which decrease the protection from pathogens and increase the risk of necrotizing enterocolitis (NEC). It also causes vascular changes with microbiota influence. Hyperoxia-induced intestinal injuries are influenced by several molecular factors, including excessive nitric oxide, the nuclear factor-κB (NF-κB) pathway, reactive oxygen species, toll-like receptor-4, CXC motif ligand-1, and interleukin-6. Nuclear factor erythroid 2-related factor 2 (Nrf2) pathways and some antioxidant cytokines or molecules including interleukin-17D, n-acetylcysteine, arginyl-glutamine, deoxyribonucleic acid, cathelicidin, and health microbiota play a role in preventing cell apoptosis and tissue inflammation from oxidative stress. NF-κB and Nrf2 pathways are essential to maintain the balance of oxidative stress and antioxidants and prevent cell apoptosis and tissue inflammation. Intestinal inflammation can lead to intestinal damage and death of the intestinal tissue, such as in NEC. This review focuses on histologic changes and molecular pathways of hyperoxia-induced intestinal injuries to establish a framework for potential interventions.

Altered Tryptophan Metabolism on the Kynurenine Pathway in Depressive Patients with Small Intestinal Bacterial Overgrowth

The causes of depression are diverse and are still not fully understood. Recently, an increasing role is attributed to nutritional and inflammatory factors. The aim of this study was to evaluate selected metabolites of the tryptophan kynurenine pathway in depressive patients with small intestinal bacterial overgrowth (SIBO). The study involved 40 healthy people (controls) and 40 patients with predominant small intestinal bacterial overgrowth (SIBO-D). The lactulose hydrogen breath test (LHBT) was performed to diagnose SIBO. The severity of symptoms was assessed using the Gastrointestinal Symptom Rating Scale (GSRS–IBS) and the Hamilton Depression Rating Scale (HAM-D). The concentration of tryptophan (TRP), kynurenine (KYN), kynurenic acid (KYNA), and quinolinic acid (QA) in urine was determined using an LC–MS/MS method, before and after cyclic treatment with an antibiotic drug, rifaximin, for three months. The number of intraepithelial lymphocytes (IELs) in the duodenum and small intestinal mucosa, fecal calprotectin (FC) and serum level of C-reactive protein (CRP) were also determined. In patients with SIBO, a higher level of KYN and QA were found as compared to the control group. These two groups also differed in KYN/TRP (higher in SIBO) and KYNA/KYN ratios (lower in SIBO). A positive correlation was found between HAM-D and the number of IELs and the level of FC. Treatment with rifaximin improves the kynurenic pathway, as well as abdominal and mental complaints. Therefore, small intestinal bacterial overgrowth can be a cause of abdominal symptoms, but also mental disorders.

Effects of the Ultrasound-Guided Stellate Ganglion Block on Hemodynamics, Stress Response, and Gastrointestinal Function in Postoperative Patients with Colorectal Cancer

Objective

The aim of the study was to study the effects of the ultrasound-guided stellate ganglion block on hemodynamics, stressful response, and postoperative gastrointestinal functions in patients with colorectal cancer.

Methods

A total of 100 patients with colorectal cancer hospitalized from January 2021 to December 2021 were selected. After anesthesia induction, the right stellate ganglion block was performed under ultrasound guidance in the research group and the general anesthesia was performed in the control group. The heart rate (HR), mean arterial pressure (MAP), epinephrine, cortisol, self-rating anxiety scale (SAS), Ramsay sedation score (RSS), postoperative bowel sound recovery time, anal exhaust time, and the incidence of gastrointestinal adverse reactions 24 hours after operation were studied pre-and post-24-hour anesthesia induction.

Results

Following 24-hour operation, the HR and MAP values were largely reduced (p < 0.05). Following 24-hour operation, epinephrine and cortisol became obviously higher (p < 0.05). After 24-hour operation, the levels of epinephrine and cortisol in the research group were greatly lower. The score of the SAS in the study cohort was less than that of the controls (p < 0.05). The RSS of the research group was obviously increased (p < 0.05). The recovery time of intestinal sound and the anal exhaust time of the study cohort became remarkably shorter (p < 0.05). The incidence of gastrointestinal adverse reactions 24 hours after operation of the study cohort was much less common (p < 0.05).

Conclusion

The ultrasound-guided stellate ganglion block can reduce the fluctuation of blood circulation during radical resection of colorectal cancer, reduce postoperative gastrointestinal dysfunction and stress reaction, relieve patients' anxiety, and contribute to the recovery of gastrointestinal function.

More Active Intestinal Immunity Developed by Obese Mice Than Non-Obese Mice After Challenged by Escherichia coli

Obese mice presented lower mortality to non-fatal pneumonia induced by Escherichia coli (E. coli) than the non-obese mice. However, it remained obscure whether the intestine contributed to the protective effect of obese mice with infection. The 64 non-obese (NOB) mice were divided into NOB-uninfected and NOB-E. coli groups, while 64 high-fat diet-induced obesity (DIO) mice were divided into DIO-uninfected and DIO-E. coli groups. Mice in E. coli groups were intranasally instilled with 40 μl E. coli (4.0 ×109 colony-forming units [CFUs]), while uninfected groups with the same volume of phosphate buffer saline (PBS). The T subsets of Intraepithelial lymphocytes (IELs) and lamina propria lymphocytes (LPLs) in the intestine were collected for flow cytometry analysis at 0, 12, 24, and 72 h post-infection, also the duodenum and colon were harvested to survey histopathological change. The results showed that the percentage of CD3+T cells in LPLs in DIO-E. coli group was significantly lower than that in the DIO-uninfected group after infection (p &lt; 0.05). The percentage of CD4+T cells in IELs in NOB-E. coli was significantly lower than that in DIO-E. coli after infection (p &lt; 0.05). The percentage of CD8+T cells in LPLs in NOB-E. coli was significantly lower than that in DIO-E. coli at 12 and 24 h (p &lt; 0.05). The immunoglobulin A (IgA)+ cells in DIO-uninfected were higher than that in NOB-uninfected at all time points (p &lt; 0.05). The IgA+ cells in DIO-E. coli were higher than that in DIO-uninfected at 12, 24, and 72 h (p &lt; 0.05). The results revealed that the level of intestinal mucosal immunity in obese mice was more active than that in non-obese mice.

Gastrointestinal Manifestations of Immunodeficiency: Imaging Spectrum

There is a wide spectrum of hereditary and acquired immunodeficiency disorders that are characterized by specific abnormalities involving a plethora of humoral, cellular, and phagocytic immunologic pathways. These include distinctive primary immunodeficiency syndromes due to characteristic genetic defects and secondary immunodeficiency syndromes, such as AIDS from HIV infection and therapy-related immunosuppression in patients with cancers or a solid organ or stem cell transplant. The gut mucosa and gut-associated lymphoid tissue (the largest lymphoid organ in the body), along with diverse commensal microbiota, play complex and critical roles in development and modulation of the immune system. Thus, myriad gastrointestinal (GI) symptoms are common in immunocompromised patients and may be due to inflammatory conditions (graft versus host disease, neutropenic enterocolitis, or HIV-related proctocolitis), opportunistic infections (viral, bacterial, fungal, or protozoal), or malignancies (Kaposi sarcoma, lymphoma, posttransplant lymphoproliferative disorder, or anal cancer). GI tract involvement in immunodeficient patients contributes to significant morbidity and mortality. Along with endoscopy and histopathologic evaluation, imaging plays an integral role in detection, localization, characterization, and distinction of GI tract manifestations of various immunodeficiency syndromes and their complications. Select disorders demonstrate characteristic findings at fluoroscopy, CT, US, and MRI that permit timely and accurate diagnosis. While neutropenic enterocolitis affects the terminal ileum and right colon and occurs in patients receiving chemotherapy for hematologic malignancies, Kaposi sarcoma commonly manifests as bull's-eye lesions in the stomach and duodenum. Imaging is invaluable in treatment follow-up and long-term surveillance as well. Online supplemental material is available for this article. ^©RSNA, 2022.

The Functional Role of Lactoferrin in Intestine Mucosal Immune System and Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), encompassing ulcerative colitis (UC) and Crohn's disease (CD), is one of the main types of intestinal inflammatory diseases with intestine mucosal immune disorder. Intestine mucosal immune system plays a remarkable and important role in the etiology and pathogenesis of IBD. Therefore, understanding the intestine mucosal immune mechanism is a key step to develop therapeutic interventions for IBD. Intestine mucosal immune system and IBD are influenced by various factors, such as inflammation, gut permeability, gut microbiota, and nutrients. Among these factors, emerging evidence show that nutrients play a key role in inflammation activation, integrity of intestinal barrier, and immune cell modulation. Lactoferrin (LF), an iron-binding glycoprotein belonging to transferrin family, is a dietary bioactive component abundantly found in mammalian milk. Notably, LF has been reported to perform diverse biological functions including antibacterial activity, anti-inflammatory activity, intestinal barrier protection, and immune cell modulation, and is involved in maintaining intestine mucosal immune homeostasis. The improved understanding of the properties of LF in intestine mucosal immune system and IBD will facilitate its application in nutrition, clinical medicine, and health. Herein, this review outlines the recent advancements on LF as a potential therapeutic intervention for IBD associated with intestine mucosal immune system dysfunction. We hope this review will provide a reference for future studies and lay a theoretical foundation for LF-based therapeutic interventions for IBD by understanding the particular effects of LF on intestine mucosal immune system.

Transcriptomics of chicken cecal tonsils and intestine after infection with low pathogenic avian influenza virus H9N2

Influenza viruses cause severe respiratory infections in humans and birds, triggering global health concerns and economic burden. Influenza infection is a dynamic process involving complex biological host responses. The objective of this study was to illustrate global biological processes in ileum and cecal tonsils at early time points after chickens were infected with low pathogenic avian influenza virus (LPAIV) H9N2 through transcriptome analysis. Total RNA isolated from ileum and cecal tonsils of non-infected and infected layers at 12-, 24- and 72-h post-infection (hpi) was used for mRNA sequencing analyses to characterize differentially expressed genes and overrepresented pathways. Statistical analysis highlighted transcriptomic signatures significantly occurring 24 and 72 hpi, but not earlier at 12 hpi. Interferon (IFN)-inducible and IFN-stimulated gene (ISG) expression was increased, followed by continued expression of various heat-shock proteins (HSP), including HSP60, HSP70, HSP90 and HSP110. Some upregulated genes involved in innate antiviral responses included DDX60, MX1, RSAD2 and CMPK2. The ISG15 antiviral mechanism pathway was highly enriched in ileum and cecal tonsils at 24 hpi. Overall, most affected pathways were related to interferon production and the heat-shock response. Research on these candidate genes and pathways is warranted to decipher underlying mechanisms of immunity against LPAIV in chickens.

Saccharomyces boulardii Ameliorates Dextran Sulfate Sodium-Induced Ulcerative Colitis in Mice by Regulating NF-κB and Nrf2 Signaling Pathways

Saccharomyces boulardii (S. boulardii) is a probiotic yeast that is widely used to treat gastrointestinal disorders. The present study is aimed to explore the therapeutic effects of S. boulardii on dextran sulfate sodium- (DSS-) induced murine ulcerative colitis (UC) and illustrate the mechanisms of action. C57BL/6 mice were administered S. boulardii (10⁵ and 10⁷ CFU/ml, p.o.) for 3 weeks and then given DSS [2.5% (w/v)] for one week. Administration of S. boulardii prevented DSS-induced reduction in body weight, diarrhea, bloody feces, decreased colon length, and loss of histological structure. Moreover, S. boulardii protected the intestinal barrier by increasing the levels of tight junction proteins zona occludens-1 and Occludin and exerted immunomodulatory effects in DSS-induced mice. Furthermore, S. boulardii suppressed the colonic inflammation by reducing the levels of Interleukin-1β, Interleukin-6, and Tumor necrosis factor alpha and restored myeloperoxidase activity in mice exposed to DSS. S. boulardii also mitigated colonic oxidative damage by increasing the levels of antioxidant enzymes (superoxide dismutase, catalase, and heme oxygenase 1) and glutathione and decreasing malondialdehyde accumulation. Further studies identified that S. boulardii suppressed the nuclear translocation of nuclear factor kappa B (NF-κB) p65 subunit by decreasing IκKα/β levels, while promoted the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) in DSS-exposed mice. Collectively, S. boulardii possessed an appreciable therapeutic effect against the experimental mice model of UC. The protective mechanism of S. boulardii may involve inhibition of NF-κB-mediated proinflammatory signaling and activation of Nrf2-modulated antioxidant defense in addition to intestinal barrier protective and immunomodulatory effects.

Eosinophils and Bacteria, the Beginning of a Story

Eosinophils are granulocytes primarily associated with TH2 responses to parasites or immune hyper-reactive states, such as asthma, allergies, or eosinophilic esophagitis. However, it does not make sense from an evolutionary standpoint to maintain a cell type that is only specific for parasitic infections and that otherwise is somehow harmful to the host. In recent years, there has been a shift in the perception of these cells. Eosinophils have recently been recognized as regulators of immune homeostasis and suppressors of over-reactive pro-inflammatory responses by secreting specific molecules that dampen the immune response. Their role during parasitic infections has been well investigated, and their versatility during immune responses to helminths includes antigen presentation as well as modulation of T cell responses. Although it is known that eosinophils can present antigens during viral infections, there are still many mechanistic aspects of the involvement of eosinophils during viral infections that remain to be elucidated. However, are eosinophils able to respond to bacterial infections? Recent literature indicates that Helicobacter pylori triggers TH2 responses mediated by eosinophils; this promotes anti-inflammatory responses that might be involved in the long-term persistent infection caused by this pathogen. Apparently and on the contrary, in the respiratory tract, eosinophils promote TH17 pro-inflammatory responses during Bordetella bronchiseptica infection, and they are, in fact, critical for early clearance of bacteria from the respiratory tract. However, eosinophils are also intertwined with microbiota, and up to now, it is not clear if microbiota regulates eosinophils or vice versa, or how this connection influences immune responses. In this review, we highlight the current knowledge of eosinophils as regulators of pro and anti-inflammatory responses in the context of both infection and naïve conditions. We propose questions and future directions that might open novel research avenues in the future.

Roux-en-Y gastric bypass potentially improved intestinal permeability by regulating gut innate immunity in diet-induced obese mice

Roux-en-Y gastric bypass (RYGB) has been demonstrated to be the most effective treatment for morbid obesity, yet the impact of RYGB on intestinal permeability is not fully known. In this work, we subjected obese mice to RYGB and sham operation procedures. Serum lipopolysaccharide (LPS) level, inflammatory cytokines and intestinal permeability were measured at 8 weeks post surgery. In contrast to sham surgery, RYGB reduced body weight, improved glucose tolerance and insulin resistance, and decreased serum levels of LPS, IL6 and TNFα. Intestinal permeability of the common limb and colon was significantly improved in the RYGB group compared to the sham group. The mRNA levels of IL1β, IL6, and TLR4 in the intestine were significantly decreased in the RYGB group compared with the sham group. The expression levels of intestinal islet-derived 3β (REG3β), islet-derived 3γ (REG3γ) and intestinal alkaline phosphatase (IAP) were higher in the RYGB group than in the sham group. In conclusion, in a diet-induced obesity (DIO) mouse model, both decreased intestinal permeability and attenuated systemic inflammation after RYGB surgery were associated with improved innate immunity, which might result from enhanced production of IAP and antimicrobial peptides.

Ethanol: striking the cardiovascular system by harming the gut microbiota

Ethanol consumption represents a significant public health problem, and excessive ethanol intake is a risk factor for cardiovascular disease (CVD), one of the leading causes of death and disability worldwide. The mechanisms underlying the effects of ethanol on the cardiovascular system are complex and not fully comprehended. The gut microbiota and their metabolites are indispensable symbionts essential for health and homeostasis and therefore, have emerged as potential contributors to ethanol-induced cardiovascular system dysfunction. By mechanisms that are not completely understood, the gut microbiota modulates the immune system and activates several signaling pathways that stimulate inflammatory responses, which in turn, contribute to the development and progression of CVD. This review summarizes preclinical and clinical evidence on the effects of ethanol in the gut microbiota and discusses the mechanisms by which ethanol-induced gut dysbiosis leads to the activation of the immune system and cardiovascular dysfunction. The cross talk between ethanol consumption and the gut microbiota and its implications are detailed. In summary, an imbalance in the symbiotic relationship between the host and the commensal microbiota in a holobiont, as seen with ethanol consumption, may contribute to CVD. Therefore, manipulating the gut microbiota, by using antibiotics, probiotics, prebiotics, and fecal microbiota transplantation might prove a valuable opportunity to prevent/mitigate the deleterious effects of ethanol and improve cardiovascular health and risk prevention.

Crohn's Disease Is Associated With Activation of Circulating Innate Lymphoid Cells

BACKGROUND

Inflammatory bowel disease (IBD) is associated with disturbed mucosal innate lymphoid cell (ILC) composition, which is correlated to the degree of intestinal inflammation. However, it remains unclear whether circulating ILCs are dysregulated in patients with IBD.

METHODS

Blood samples from 53 patients with Crohn's disease (CD), 43 patients with ulcerative colitis (UC), and 45 healthy control subjects (HC) were analyzed by flow cytometry for markers of ILC subsets (ILC1, ILC2, and ILC precursors [ILCp]) and selected IBD-relevant proteins, as predicted by previous genome-wide association studies. A dimensionality reduction approach to analyzing the data was used to characterize circulating ILCs.

RESULTS

The frequency of ILCp expressing the ILC3 activation markers NKp44 and CD56 was increased in CD versus HC and UC (NKp44) or in CD versus HC (CD56), whereas the CD45RA+ ILCp were reduced in CD versus UC. Furthermore, the activation marker HLA-DR was increased on ILC1 and ILC2 in CD versus HC. Interestingly, the IBD-related protein SLAMF1 was upregulated on ILC2 from both CD and UC samples as compared with HC samples. In active CD, SLAMF1+ ILC2 frequency was negatively correlated with disease severity (Harvey-Bradshaw index). The characterization of SLAMF1+ ILC2 revealed a higher expression of the ILC2 markers CRTH2, CD161, and GATA3 as compared with SLAMF1- ILC2.

CONCLUSIONS

In line with the systemic nature of CD inflammation, our findings point toward the activation of ILCs in the blood of patients with CD. Furthermore, in active CD, circulating SLAMF1+ ILC2 are increased in patients with less active disease, introducing SLAMF1+ ILC2 as interesting therapeutic targets deserving further exploration.

Mucosal Epithelial Jak Kinases in Health and Diseases

Janus kinases (Jaks) are a family of nonreceptor tyrosine kinase that include four different members, viz., Jak1, Jak2, Jak3, and Tyk2. Jaks play critical roles in immune cells functions; however, recent studies suggest they also play essential roles in nonimmune cell physiology. This review highlights the significance of epithelial Jaks in understanding the molecular basis of some of the diseases through regulation of epithelial-mesenchymal transition, cell survival, cell growth, development, and differentiation. Growth factors and cytokines produced by the cells of hematopoietic origin use Jak kinases for signal transduction in both immune and nonimmune cells. Among Jaks, Jak3 is widely expressed in both immune cells and in intestinal epithelial cells (IECs) of both humans and mice. Mutations that abrogate Jak3 functions cause an autosomal severe combined immunodeficiency disease (SCID) while activating Jak3 mutations lead to the development of hematologic and epithelial cancers. A selective Jak3 inhibitor CP-690550 (Xeljanz) approved by the FDA for certain chronic inflammatory conditions demonstrates immunosuppressive activity in rheumatoid arthritis, psoriasis, and organ transplant rejection. Here, we also focus on the consequences of Jak3-directed drugs on adverse effects in light of recent discoveries in mucosal epithelial functions of Jak3 with some information on other Jaks. Lastly, we brief on structural implications of Jak3 domains beyond the immune cells. As information about the roles of Jak3 in gastrointestinal functions and associated diseases are only just emerging, in the review, we summarize its implications in gastrointestinal wound repair, inflammatory bowel disease, obesity-associated metabolic syndrome, and epithelial cancers. Lastly, we shed lights on identifying potential novel targets in developing therapeutic interventions of diseases associated with dysfunctional IEC.

Leukaemia Infection Diagnosis and Intestinal Flora Disorder

Leukaemia is the most common malignant tumor in childhood and can be cured by chemotherapy. Infection is an important cause of treatment-related death and treatment failure in childhood leukaemia. Recent studies have shown that the correlation between the occurrence of leukaemia infection and the intestinal flora has attracted more and more attention. Intestinal flora can affect the body's physiological defense and immune function. When intestinal microflora disorder occurs, metabolites/microorganisms related to intestinal flora alterations and even likely the associated morpho-functional alteration of the epithelial barrier may be promising diagnostic biomarkers for the early diagnosis of leukaemia infection. This review will focus on the interaction between leukaemia infection and intestinal flora, and the influence of intestinal flora in the occurrence and development of leukaemia infection.

Gastrointestinal and renal complications in SARS-CoV-2-infected patients: Role of immune system

The recent severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) disease has been accompanied by various gastrointestinal (GI) and renal manifestations in significant portion of infected patients. Beside studies on the respiratory complications of coronavirus infection, understanding the essential immunological processes underlying the different clinical manifestations of virus infection is crucial for the identification and development of effective therapies. In addition to the respiratory tract, the digestive and urinary systems are the major sources of virus transmission. Thus, knowledge about the invasion mechanisms of SARS‐CoV‐2 in these systems and the immune system responses is important for implementing the infection prevention strategies. This article presents an overview of the gut and renal complications in SARS‐CoV‐2 infection. We focus on how SARS‐CoV‐2 interacts with the immune system and the consequent contribution of immune system, gut, and renal dysfunctions in the development of disease.

Exposures to uranium and arsenic alter intraepithelial and innate immune cells in the small intestine of male and female mice

Human exposures to environmental metals, including uranium (U) and arsenic (As) are a global public health concern. Chronic exposures to U and As are linked to many adverse health effects including, immune suppression and autoimmunity. The gastrointestinal (GI) tract is home to many immune cells vital in the maintenance of systemic immune health. However, very little is known about the immunotoxicity of U and As at this site. The present study examined the burden of U and As exposure in the GI tract as well as the resultant immunotoxicity to intraepithelial lymphocytes (IELs) and innate immune cells of the small intestine following chronic drinking water exposures of male and female mice to U (in the form of uranyl acetate, UA) and As (in the form of sodium arsenite, As3+). Exposure to U or As3+ resulted in high levels of U or As in the GI tract of male and female mice, respectively. A reduction of small intestinal CD4+ IELs (TCRαβ+, CD8αα+) was found following As3+ exposure, whereas U produced widespread suppression of CD4- IEL subsets (TCRαβ+ and TCRγδ+). Evaluation of innate immune cell subsets in the small intestinal lamina propria revealed a decrease in mature macrophages, along with a corresponding increase in immature/proinflammatory macrophages following As3+ exposures. These data show that exposures to two prevalent environmental contaminants, U and As produce significant immunotoxicity in the GI tract. Collectively, these findings provide a critical framework for understanding the underlying immune health issues reported in human populations chronically exposed to environmental metals.

Thumb sucking or nail biting in childhood and adolescence is associated with an increased risk of Crohn's disease: results from a large case-control study

BACKGROUND

The hygiene hypothesis suggests that a reduction in microbial exposure contributes to an impaired immune response later in life and increases the incidence of immune-mediated diseases such as inflammatory bowel diseases (IBD). Thumb sucking and nail biting are two early habits that modulate the oral microbiota composition and antigen load.

OBJECTIVE

We hypothesized a lower risk of Crohn's disease (CD) and ulcerative colitis (UC) in adults with prior thumb sucking and nail biting.

METHODS

918 IBD cases and their 918 siblings without IBD were asked to fill out a survey containing 32 questions on environmental factors in childhood and early adulthood. Prevalence of thumb sucking and/or nail biting at the usually well-remembered time of (1) school enrollment and (2) coming-of-age ceremonies was the predefined combined risk factor of this study.

RESULTS

65% of the patients were female and 57% suffered from CD. About 49% of IBD patients but only 44% of their siblings reported thumb sucking/nail biting at the time of school enrollment or coming-of-age (p = .007). Sensitivity analysis revealed that this difference was observed in patients with CD (50% versus 41%; RR= 1.22; 95% CI 1.09-1.37, p = .001) but not in patients with UC (49% versus 48%; RR= 1.02; 95% CI 0.90-1.17; p = .83).

CONCLUSION

Contrary to our expectation and challenging the hygiene hypothesis, we found that common oral habits are not protective against IBD. Instead, nail biting at the time of school enrollment and coming-of-age was a statistically significant risk factor for CD in our cohort. Key summary Evidence available before this study: The hygiene hypothesis suggests that a reduction in microbial exposure due to improved health activities has contributed to an immunological imbalance in the intestine and an increased incidence of allergic and autoimmune diseases. A population-based birth cohort study has demonstrated that thumb-sucking and nail biting in children lead to a reduction of the risk of atopic sensitization, asthma, and hay fever. Added value of this study: Contrary to the hypothesis, thumb sucking and nail biting were not associated with a reduced risk of IBD. Instead, thumb sucking and/or nail biting at the usually well-remembered points in time of school enrollment and of religious or secular coming-of-age ceremonies was associated with a higher risk of Crohn's disease but not of ulcerative colitis. Our data did not support the hygiene hypothesis, one pathogenic concept in the context of IBD.

Vitamin D and intestinal homeostasis: Barrier, microbiota, and immune modulation

Vitamin D plays a pivotal role in intestinal homeostasis. Vitamin D can impact the function of virtually every cell in the gut by binding to its intracellular receptor (VDR) and subsequently transcribing relevant genes. In the lumen, the mucus layer and the underlying epithelium serve to keep resident microbiota at bay. Vitamin D ensures an appropriate level of antimicrobial peptides in the mucus and maintains epithelial integrity by reinforcing intercellular junctions. Should bacteria penetrate the epithelial layer and enter the interstitium, immune sentinel cells (e.g. macrophages, dendritic cells, and innate lymphoid cells) elicit inflammation and trigger the adaptive immune response by activating Th1/Th17 cells. Vitamin D/VDR signaling in these cells ensures clearance of the bacteria. Subsequently, vitamin D also quiets the adaptive immune system by suppressing the Th1/Th17 cells and favoring Treg cells. The importance of vitamin D/VDR signaling in intestinal homeostasis is evidenced by the development of a chronic inflammatory state (e.g. IBD) when this signaling system is disrupted.

Diagnostic Sensitivity of NLR and PLR in Early Diagnosis of Gastric Cancer

The neutrophil-lymphocyte ratio (NLR) and the platelet-lymphocyte ratio (PLR) are markers of systemic inflammation. However, there is little evidence of the value of inflammation in the early diagnosis of gastric cancer (GC). A total of 2,606 patients diagnosed with GC in the past three years and 3,219 healthy controls over the same period were included in this study. Peripheral blood samples were obtained to analyze the NLR, PLR, carcinoembryonic antigen (CEA), and carbohydrate antigen 19-9 (CA19-9). The optimal cutoff levels for the NLR and PLR were defined by receiver operating characteristic (ROC) curve analysis (NLR = 2.258, PLR = 147.368). The value of different biomarkers for diagnosing GC was compared by the area under the curve (AUC). The NLR and PLR showed diagnostic sensitivity in GC (AUC = 0.715, AUC = 0.707). Using the Bonferroni correction, the NLR and PLR were superior to CEA and CA19-9 in the diagnosis of GC (P < 0.0001). The systemic inflammatory markers were significantly higher in the early stage of GC than tumor markers. After grouping patients and healthy controls by gender, we found that the diagnostic significance of combined NLR and PLR for GC was greater in male patients than in female patients (P < 0.0001). The diagnostic value of the NLR and PLR in GC is higher than that of the traditional tumor markers CEA and CA19-9. Systemic markers of inflammation are more valuable in male than female patients.

In-Vitro Cell Culture for Efficient Assessment of Mycotoxin Exposure, Toxicity and Risk Mitigation

Mycotoxins are toxic secondary fungal metabolites that commonly contaminate crops and food by-products and thus, animal feed. Ingestion of mycotoxins can lead to mycotoxicosis in both animals and humans, and at subclinical concentrations may affect animal production and adulterate feed and animal by-products. Mycotoxicity mechanisms of action (MOA) are largely unknown, and co-contamination, which is often the case, raises the likelihood of mycotoxin interactions. Mitigation strategies for reducing the risk of mycotoxicity are diverse and may not necessarily provide protection against all mycotoxins. These factors, as well as the species-specific risk of toxicity, collectively make an assessment of exposure, toxicity, and risk mitigation very challenging and costly; thus, in-vitro cell culture models provide a useful tool for their initial assessment. Since ingestion is the most common route of mycotoxin exposure, the intestinal epithelial barrier comprised of epithelial cells (IECs) and immune cells such as macrophages, represents ground zero where mycotoxins are absorbed, biotransformed, and elicit toxicity. This article aims to review different in-vitro IEC or co-culture models that can be used for assessing mycotoxin exposure, toxicity, and risk mitigation, and their suitability and limitations for the safety assessment of animal foods and food by-products.

Interleukin-23 Blockers: Born to be First-line Biologic Agents in Inflammatory Bowel Disease?

Over the past decades, the advent of anti-TNF agents has dramatically changed the treatment algorithms for IBD. However, primarily and more importantly, secondary loss of response to anti-TNF agents, is often observed. Thus, new treatment options have been actively explored and some have already been incorporated in the current clinical practice. Among the class of anti-cytokine agents, the anti-IL12/IL23 monoclonal antibodies (mAbs) have been first presented, in clinical practice, by the anti-p40 mAb ustekinumab in Crohn's disease (CD). More selective anti-IL23 agents (anti-p19) have shown efficacy and are being further developed, in contrast to agents inhibiting IL-17 downstream, which have failed in IBD clinical trials despite their clear efficacy in psoriasis.

Interactions between Intestinal Microflora/Probiotics and the Immune System

The digestive tract is home to millions of microorganisms and is the main and most important part of bacterial colonization. On one hand, the abundant bacterial community in intestinal tissues may pose potential health challenges such as inflammation and sepsis in cases of opportunistic invasion. Thus, the immune system has evolved and adapted to maintain the symbiotic relationship between host and microbiota. On the other hand, the intestinal microflora also exerts an immunoregulatory function to maintain host immune homeostasis, which cannot be neglected. In addition, the interaction of either microbiota or probiotics with immune system in regard to therapeutic applications is an area of great interest, and novel therapeutic strategies remain to be investigated. The review will elucidate interactions between intestinal microflora/probiotics and the immune system as well as novel therapeutic strategies.

Beneficial Effects of Oat Beta-Glucan Dietary Supplementation in Colitis Depend on its Molecular Weight

Background: Inflammatory bowel diseases are an important health problem. Therefore, the aim of the present study was to compare the impact of isolated oat beta-glucan fractions of low and high molecular weight, taken as dietary supplementation, on inflammatory markers in the colitis model. Methods: Two groups of Sprague–Dawley rats—control and with experimentally induced colitis—were subsequently divided into three subgroups and fed over 21 days feed supplemented with 1% of low (βGl) or high (βGh) molecular weight oat beta-glucan fraction or feed without supplementation. The level of colon inflammatory markers, cytokines, and their receptors’ genes expressions and immune cells numbers were measured by ELISA, RT-PCR, and by flow cytometry methods, respectively. Results: The results showed moderate inflammation affecting the colon mucosa and submucosa, with significant changes in the number of lymphocytes in the colon tissue, elevated cytokines and eicosanoid levels, as well as disruption of the main cytokine and chemokine cell signaling pathways in colitis rats. Beta-glucans supplementation caused a reverse in the percentage of lymphocytes with stronger effects of βGh and reduction of the levels of the inflammatory markers, and improvement of cytokine and chemokine signaling pathways with stronger effects of βGl supplementation. Conclusions: The results indicate the therapeutic effect of dietary oat beta-glucan supplementation in the colitis in evident relation to the molecular weight of polymer.

Gut microbiota promote the inflammatory response in the pathogenesis of systemic lupus erythematosus

OBJECTIVES

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease whose onset and progression are affected by genetic and environmental factors. The purpose of this study is to identify the influence of gut microbiota in the pathogenesis of SLE, and to investigate the mechanism involved.

METHODS

Fecal microbiota from C57/BL6 mice and SLE prone mice were examined using next-generation sequencing (NGS). Germ free mice were given fecal microbiota transplantation (FMT), and their gut microbiome and gene expression in recipients' colons were examined by NGS. The anti-double stranded DNA (anti-dsDNA) antibodies in recipients were determined using an enzyme-linked immunosorbent assay (ELISA). The immune cell profiles of mice were analyzed by flow cytometry at the 3rd week after FMT, and the expression of genes associated with SLE after FMT was determined using quantitative real-time PCR (qRT-PCR).

RESULTS

The fecal microbiota of SLE mice had lower community richness and diversity than healthy mice. Fecal microbiota of recipient mice were similar to their donors. Fecal microbiome from SLE mice could lead to a significant increase of anti-dsDNA antibodies and promote the immune response in recipient mice. Our results also indicated that fecal microbiome from SLE mice resulted in significant changes in the distribution of immune cells and upregulated expression of certain lupus susceptibility genes.

CONCLUSIONS

SLE is associated with alterations of gut microbiota. Fecal microbiome from SLE mice can induce the production of anti-dsDNA antibodies in germ free mice and stimulate the inflammatory response, and alter the expression of SLE susceptibility genes in these mice.

Human Gut-Associated Natural Killer Cells in Health and Disease

It is well established that natural killer (NK) cells are involved in both innate and adaptive immunity. Indeed, they can recognize molecules induced at the cell surface by stress signals and virus infections. The functions of NK cells in the gut are much more complex. Gut NK cells are not precisely organized in lymphoid aggregates but rather scattered in the epithelium or in the stroma, where they come in contact with a multitude of antigens derived from commensal or pathogenic microorganisms in addition to components of microbiota. Furthermore, NK cells in the bowel interact with several cell types, including epithelial cells, fibroblasts, macrophages, dendritic cells, and T lymphocytes, and contribute to the maintenance of immune homeostasis and development of efficient immune responses. NK cells have a key role in the response to intestinal bacterial infections, primarily through production of IFNγ, which can stimulate recruitment of additional NK cells from peripheral blood leading to amplification of the anti-bacterial immune response. Additionally, NK cells can have a role in the pathogenesis of gut autoimmune inflammatory bowel diseases (IBDs), such as Crohn's Disease and Ulcerative Colitis. These diseases are considered relevant to the generation of gastrointestinal malignancies. Indeed, the role of gut-associated NK cells in the immune response to bowel cancers is known. Thus, in the gut immune system, NK cells play a dual role, participating in both physiological and pathogenic processes. In this review, we will analyze the known functions of NK cells in the gut mucosa both in health and disease, focusing on the cross-talk among bowel microenvironment, epithelial barrier integrity, microbiota, and NK cells.

Effects of force-feeding on immunology, digestive function and oxidative stress in the duodenal and jejunal mucosa of Pekin ducks

Force-feeding was considered as a traditional high-efficiency approach to improve growth performance and accelerate fat deposition of Pekin ducks. However, force-feeding is a serious violation of international advocacy on animal welfare, because it can induce serious injuries to animals, such as damages to the digestive tract, effects on immunity and even severe oxidative stress. Therefore, it is urgent to stop force-feeding. The aim of this study was to determine the effects of force feeding on immune function, digestive function and oxidative stress in the mucosa of duodenum and jejunum of Pekin ducks. A total of 500 ducks were randomly divided into two groups. The control group was allowed to feed freely on a basal diet. The experimental group was force-fed by inserting a plastic feeding tube 8 to 10 inches long down the esophagus for 6 days. Compared with the control group, there was a significant (P<0.05) increase in serum diamine oxidase, d-lactic acid, endotoxin and corticosterone levels in the force-feeding group. The crypt depth in duodenum and jejunum showed significant differences (P<0.05) between the two groups and the intestinal villus epithelium cell was severely damaged in force-feeding group. Similarly, the activities of digestive enzymes as well as the levels of immune function in the duodenal and jejunal mucosa in the force-feeding group were significantly higher than the control group (P<0.05). However, there was a significant decrease in the superoxide dismutase, glutathione peroxidase and catalase levels with a marked increase in malondialdehyde level in duodenal and jejunal mucosa (P<0.05). In summary, at the end of the fattening period with force-feeding for 6 days, Pekin ducks experienced an adverse effect on the integrity of their duodenal and jejunal mucosa epithelium cell as well as their immune function and antioxidant capacity of Pekin ducks but also had improvement in digestive enzyme activities.

Regulatory cells in the skin: Pathophysiologic role and potential targets for anti-inflammatory therapies

Inflammation is a fundamental defense mechanism to protect the body from danger, which becomes potentially harmful if it turns chronic. Therapeutic strategies aimed at specifically blocking proinflammatory signals, particularly cytokines, such as IL-4, IL-6, IL-13, IL-17A, or TNF-α, have substantially improved our ability to effectively and safely treat chronic inflammatory diseases. Much less effort has been made to better understand the role of potential anti-inflammatory mechanisms. Here we summarize the current understanding of regulatory cell populations in the context of chronic inflammation, namely macrophages, Langerhans cells, myeloid-derived suppressor cells, and regulatory T and B lymphocytes. Emphasis is given to the skin because many different immune-related diseases occur in the skin. Development, phenotype, function, and evidence for their role in animal models of inflammation, as well as in the corresponding human diseases, are described. Finally, the feasibility of using regulatory cells as targets for potentially disease-modifying therapeutic strategies is discussed.