Dietary influences on intestinal immunity

Fructooligosaccharides benefits on glucose homeostasis upon high-fat diet feeding require type 2 conventional dendritic cells

Diet composition impacts metabolic health and is now recognized to shape the immune system, especially in the intestinal tract. Nutritional imbalance and increased caloric intake are induced by high-fat diet (HFD) in which lipids are enriched at the expense of dietary fibers. Such nutritional challenge alters glucose homeostasis as well as intestinal immunity. Here, we observed that short-term HFD induced dysbiosis, glucose intolerance and decreased intestinal RORγt+ CD4 T cells, including peripherally-induced Tregs and IL17-producing (Th17) T cells. However, supplementation of HFD-fed male mice with the fermentable dietary fiber fructooligosaccharides (FOS) was sufficient to maintain RORγt+ CD4 T cell subsets and microbial species known to induce them, alongside having a beneficial impact on glucose tolerance. FOS-mediated normalization of Th17 cells and amelioration of glucose handling required the cDC2 dendritic cell subset in HFD-fed animals, while IL-17 neutralization limited FOS impact on glucose tolerance. Overall, we uncover a pivotal role of cDC2 in the control of the immune and metabolic effects of FOS in the context of HFD feeding.

A comprehensive review of medium chain monoglycerides on metabolic pathways, nutritional and functional properties, nanotechnology formulations and applications in food system

A large and growing body of literature has investigated the broad antibacterial spectrum and strong synergistic antimicrobial activity of medium chain monoglycerides (MCMs) have been widely investigated. Recently, more and more researches have focused on the regulation of MCMs on metabolic health and gut microbiota both in vivo and in vitro. The current review summarizes the digestion, absorption and metabolism of MCMs. Subsequently, it focuses on the functional and nutritional properties of MCMs, including the antibacterial and antiviral characteristics, the modulation of metabolic balance, the regulation of gut microbiota, and the improvement in intestinal health. Additionally, we discuss the most recent developments and application of MCMs using nanotechnologies in food industry, poultry and pharmaceutical industry. Additionally, we analyze recent application examples of MCMs and their nanotechnology formation used in food. The development of nanotechnology platforms facilitating molecular encapsulation and functional presentation contribute to the application of hydrophobic fatty acids and monoglycerides in food preservation and their antibacterial effectiveness. This study emphasizes the metabolic mechanisms and biological activity of MCMs by summarizing the prevailing state of knowledge on this topic, as well as providing insights into prospective techniques for developing the beneficial applications of MCMs to realize the industrialized production.

Immune cell trafficking: a novel perspective on the gut-skin axis

Immune cell trafficking, an essential mechanism for maintaining immunological homeostasis and mounting effective responses to infections, operates under a stringent regulatory framework. Recent advances have shed light on the perturbation of cell migration patterns, highlighting how such disturbances can propagate inflammatory diseases from their origin to distal organs. This review collates and discusses current evidence that demonstrates atypical communication between the gut and skin, which are conventionally viewed as distinct immunological spheres, in the milieu of inflammation. We focus on the aberrant, reciprocal translocation of immune cells along the gut-skin axis as a pivotal factor linking intestinal and dermatological inflammatory conditions. Recognizing that the translation of these findings into clinical practices is nascent, we suggest that therapeutic strategies aimed at modulating the axis may offer substantial benefits in mitigating the widespread impact of inflammatory diseases.

Vitamin D3 can effectively and rapidly clear largemouth bass ranavirus by immunoregulation

Largemouth bass ranavirus (LMBV) is a highly destructive pathogen that causes significant mortality rates among largemouth bass populations. Unfortunately, there is a dearth of drug development efforts specifically aimed at treating LMBV. To address this, our study sought to investigate the potential effectiveness of incorporating varying doses of VD3 into the diet as a treatment for LMBV. Through qRT-PCR and semi-qPCR, we observed significant suppression and clearance of LMBV pathogens in largemouth bass fed with 15000 IU/Kg and 20000 IU/Kg of VD3 within 14 days. In addition, VD3 treatment significantly increased the expression levels of key immune-related genes such as IL-1β, IFN-γ, Mx, and IgM. Encouragingly, we observed that VD3 significantly increased antioxidant and immune activities such as TSOD, TAOC and C3 in serum and maintained total protein levels. Additionally, tissue pathology sections highlighted a dose-dependent relationship between VD3 supplementation and tissue damage, with the 15000 IU and 20000 IU groups exhibiting minimal damage. In conclusion, a reasonable concentration of VD3 effectively reduced LMBV replication and tissue damages, while improved immune-related genes expression and serum biochemical indices. These findings declare the considerable therapeutic potential of VD3 supplementation for combating LMBV disease and provide an alternative treatment option for fish farming.

Retinoid X receptor gamma dictates the activation threshold of group 2 innate lymphoid cells and limits type 2 inflammation in the small intestine

Group 2 innate lymphoid cells (ILC2s) are crucial in promoting type 2 inflammation that contributes to both anti-parasite immunity and allergic diseases. However, the molecular checkpoints in ILC2s that determine whether to immediately launch a proinflammatory response are unknown. Here, we found that retinoid X receptor gamma (Rxrg) was highly expressed in small intestinal ILC2s and rapidly suppressed by alarmin cytokines. Genetic deletion of Rxrg did not impact ILC2 development but facilitated ILC2 responses and the tissue inflammation induced by alarmins. Mechanistically, RXRγ maintained the expression of its target genes that support intracellular cholesterol efflux, which in turn reduce ILC2 proliferation. Furthermore, RXRγ expression prevented ILC2 response to mild stimulations, including low doses of alarmin cytokine and mechanical skin injury. Together, we propose that RXRγ expression and its mediated lipid metabolic states function as a cell-intrinsic checkpoint that confers the threshold of ILC2 activation in the small intestine.

Characterization of Bovine Intraepithelial T Lymphocytes in the Gut

Intraepithelial T lymphocytes (T-IELs), which constitute over 50% of the total T lymphocytes in the animal, patrol the mucosal epithelial lining to defend against pathogen invasion while maintaining gut homeostasis. In addition to expressing T cell markers such as CD4 and CD8, T-IELs display T cell receptors (TCR), including either TCRαβ or TCRγδ. Both humans and mice share similar T-IEL subsets: TCRγδ+, TCRαβ+CD8αα+, TCRαβ+CD4+, and TCRαβ+CD8αβ+. Among these subsets, human T-IELs are predominantly TCRαβ+ (over 80%), whereas those in mice are mostly TCRγδ+ (~60%). Of note, the majority of the TCRγδ+ subset expresses CD8αα in both species. Although T-IELs have been extensively studied in humans and mice, their profiles in cattle have not been well examined. Our study is the first to characterize bovine T-IELs using flow cytometry, where we identified several distinct features. The percentage of TCRγδ+ was comparable to that of TCRαβ+ T-IELs (both ~50% of CD3+), and the majority of bovine TCRγδ+ T-IELs did not express CD8 (CD8-) (above 60%). Furthermore, about 20% of TCRαβ+ T-IELs were CD4+CD8αβ+, and the remaining TCRαβ+ T-IELs were evenly distributed between CD4+ and CD8αβ+ (~40% of TCRαβ+ T-IELs each) with no TCRαβ+CD8αα+ identified. Despite these unique properties, bovine T-IELs, similar to those in humans and mice, expressed a high level of CD69, an activation and tissue-retention marker, and a low level of CD62L, a lymphoid adhesion marker. Moreover, bovine T-IELs produced low levels of inflammatory cytokines such as IFNγ and IL17A, and secreted small amounts of the immune regulatory cytokine TGFβ1. Hence, bovine T-IELs' composition largely differs from that of human and mouse, with the dominance of the CD8- population among TCRγδ+ T-IELs, the substantial presence of TCRαβ+CD4+CD8αβ+ cells, and the absence of TCRαβ+CD8αα+ T-IELs. These results provide the groundwork for conducting future studies to examine how bovine T-IELs respond to intestinal pathogens and maintain the integrity of the gut epithelial barrier in animals.

Unleashing nature's potential and limitations: Exploring molecular targeted pathways and safe alternatives for the treatment of multiple sclerosis (Review)

Driven by the limitations and obstacles of the available approaches and medications for multiple sclerosis (MS) that still cannot treat the disease, but only aid in accelerating the recovery from its attacks, the use of naturally occurring molecules as a potentially safe and effective treatment for MS is being explored in model organisms. MS is a devastating disease involving the brain and spinal cord, and its symptoms vary widely. Multiple molecular pathways are involved in the pathogenesis of the disease. The present review showcases the recent advancements in harnessing nature's resources to combat MS. By deciphering the molecular pathways involved in the pathogenesis of the disease, a wealth of potential therapeutic agents is uncovered that may revolutionize the treatment of MS. Thus, a new hope can be envisioned in the future, aiming at paving the way toward identifying novel safe alternatives to improve the lives of patients with MS.

The intestinal immune system and gut barrier function in obesity and ageing

Obesity and ageing predispose to numerous, yet overlapping chronic diseases. For example, metabolic abnormalities, including insulin resistance (IR) and type 2 diabetes (T2D) are important causes of morbidity and mortality. Low-grade chronic inflammation of tissues, such as the liver, visceral adipose tissue and neurological tissues, is considered a significant contributor to these chronic diseases. Thus, it is becoming increasingly important to understand what drives this inflammation in affected tissues. Recent evidence, especially in the context of obesity, suggests that the intestine plays an important role as the gatekeeper of inflammatory stimuli that ultimately fuels low-grade chronic tissue inflammation. In addition to metabolic diseases, abnormalities in the intestinal mucosal barrier have been linked to a range of other chronic inflammatory conditions, such as neurodegeneration and ageing. The flow of inflammatory stimuli from the gut is in part controlled by local immunological inputs impacting the intestinal barrier. Here, we will review the impact of obesity and ageing on the intestinal immune system and its downstream consequences on gut barrier function, which is strongly implicated in the pathogenesis of obesity and age-related diseases. In particular, we will discuss the effects of age-related intestinal dysfunction on neurodegenerative diseases.

Modulation by luminal factors on the functions and migration of intestinal innate immunity

Luminal antigens, nutrients, metabolites from commensal bacteria, bile acids, or neuropeptides influence the function and trafficking of immune cells in the intestine. Among the immune cells in the gut, innate lymphoid cells, including macrophages, neutrophils, dendritic cells, mast cells, and innate lymphoid cells, play an important role for the maintenance of intestinal homeostasis through a rapid immune response to luminal pathogens. These innate cells are influenced by several luminal factors, possibly leading to dysregulated gut immunity and intestinal disorders such as inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), and intestinal allergy. Luminal factors are sensed by distinct neuro-immune cell units, which also have a strong impact on immunoregulation of the gut. Immune cell trafficking from the blood stream through the lymphatic organ to lymphatics, an essential function for immune responses, is also modulated by luminal factors. This mini-review examines knowledge of luminal and neural factors that regulate and modulate response and migration of leukocytes including innate immune cells, some of which are clinically associated with pathological intestinal inflammation.

Gut immune cells and intestinal niche imprinting

The intestine comprises the largest proportion of immune cells in the body. It is continuously exposed to new antigens and immune stimuli from the diet, microbiota but also from intestinal pathogens. In this review, we describe the main populations of immune cells present along the intestine, both from the innate and adaptive immune system. We later discuss how intestinal niches significantly impact the phenotype and function of gut immune populations at steady state and upon infection.

Weaning diet supplemented with health-promoting feed additives influences microbiota and immune response in piglets challenged with Salmonella

The aim of this study was to evaluate the potential of micronutrients and feed additives to modulate intestinal microbiota and systemic and mucosal immune responses in weaned pigs infected with Salmonella. At weaning, 32 litters of 12 piglets each were allocated to four dietary treatments: 1) control diet (CTRL), 2) CTRL supplemented with chlortetracycline (ATB), 3) CTRL supplemented with a cocktail of feed additives (CKTL); and 4) CKTL diet containing bovine colostrum in replacement of spray-dry animal plasma (CKTL+COL). The CKTL supplement included cranberry extract, encapsulated carvacrol and yeast-derived products and an enriched selenium and vitamin premix. Three weeks after weaning, four pigs per litter were orally inoculated with Salmonella Typhimurium DT104. Half of them were euthanized 3 days post-infection (dpi) and the other half, 7 dpi. The expression of IL6, TNF, IL8, monocyte chemoattractant protein 1 (MCP1), IFNG, cyclooxygenase 2 (COX2), glutathione peroxidase 2 (GPX2) and β-defensin 2 (DEFB2) showed a peaked response at 3 dpi (P < 0.05). Results also revealed that DEFB2 expression was higher at 3 dpi in CTRL and CKTL groups than in ATB (P = 0.01 and 0.06, respectively) while GPX2 gene was markedly increased at 3 and 7 dpi in pigs fed CKTL or CKTL+COL diet compared to CTRL pigs (P < 0.05). In piglets fed CKTL or CKTL+COL diet, intestinal changes in microbial communities were less pronounced after exposure to Salmonella compared to CTRL and progressed faster toward the status before Salmonella challenge (AMOVA P < 0.01). Furthermore, the relative abundance of several families was either up- or down-regulated in pigs fed CKTL or CKTL+COL diet after Salmonella challenge. In conclusion, weaning diet enriched with bovine colostrum, vitamins and mixture of feed additives mitigated the influence of Salmonella infection on intestinal microbial populations and modulate systemic and intestinal immune defences.

A new SVWC protein functions as a pattern recognition protein in antibacterial responses in Chinese mitten crab (Eriocheirsinensis)

Because invertebrates lack acquired immunity, they rely primarily on the innate immune system to defend themselves against viral and bacterial infections. SVWC, also called Vago, is a class of small-molecule proteins characterized by a single von Willebrand factor C-domain and appears to be restricted to arthropods. It has been reported that SVWC is involved in antiviral immunity in invertebrates, but whether it is involved in antimicrobial immunity and the mechanism of its involvement in antimicrobial immunity remains unclear. In this study, we identified a novel SVWC gene in Eriocheir sinensis and named it EsSVWC. EsSVWC was found to respond positively to bacterial stimulation and to regulate the expression of related antimicrobial peptides (AMPs). The EsSVWC protein recognized and bound to a variety of pathogen-associated molecular patterns (PAMPs) but did not exhibit direct bactericidal effects. Thus, the EsSVWC protein in crabs helps resist bacterial infection and improve survival rates. In summary, EsSVWC may regulate the innate immune system of crabs in response to microbial invasion in an indirect manner.

Epigenomic effects of vitamin D in colorectal cancer

Vitamin D regulates a plethora of physiological processes in the human body and has been proposed to exert several anticancer effects. Epigenetics plays an important role in regulating vitamin D actions. In this review, we highlight the recent advances in the understanding of different epigenetic factors such as lncRNAs, miRNAs, methylation and acetylation influenced by vitamin D and its downstream targets in colorectal cancer to find more potential therapeutic targets. We discuss how vitamin D exerts anticancer properties through interactions between the vitamin D receptor and genes (e.g., SLC30A10), the microenvironment, microbiota and other factors in colorectal cancer. Developing therapeutic approaches targeting the vitamin D signaling system will be aided by a better knowledge of the epigenetic impact of vitamin D.

Regulation of intestinal immunity by dietary fatty acids

Dietary fatty acids are absorbed through the intestine and are fundamental for cellular energy provision and structural formation. Dietary fatty acids profoundly affect intestinal immunity and influence the development and progression of inflammatory bowel disease, intestinal infections and tumors. Although different types of fatty acids exert differential roles in intestinal immunity, a western diet, rich in saturated fatty acids with abundant carbohydrates and studied as high-fat diet (HFD) in animal experiments, disturbs intestinal homeostasis and plays a pathogenic role in intestinal inflammatory diseases. Here, we review recent findings on the regulation of intestinal immunity by dietary fatty acids, focusing on HFD. We summarize HFD-altered immune responses leading to susceptibility to intestinal pathology and dissect the mechanisms involving the impact of HFD on immune cells, intestinal epithelial cells and the microbiota. Understanding the perturbation of intestinal immunity by HFD will provide new strategies for prevention and treatment of intestinal inflammatory diseases.

Three Layers of Intestinal γδ T Cells Talk Different Languages With the Microbiota

The mucosal surfaces of our body are the main contact site where the immune system encounters non-self molecules from food-derived antigens, pathogens, and symbiotic bacteria. γδ T cells are one of the most abundant populations in the gut. Firstly, they include intestinal intraepithelial lymphocytes, which screen and maintain the intestinal barrier integrity in close contact with the epithelium. A second layer of intestinal γδ T cells is found among lamina propria lymphocytes (LPL)s. These γδ LPLs are able to produce IL-17 and likely have functional overlap with local Th17 cells and innate lymphoid cells. In addition, a third population of γδ T cells resides within the Peyer´s patches, where it is probably involved in antigen presentation and supports the mucosal humoral immunity. Current obstacles in understanding γδ T cells in the gut include the lack of information on cognate ligands of the γδ TCR and an incomplete understanding of their physiological role. In this review, we summarize and discuss what is known about different subpopulations of γδ T cells in the murine and human gut and we discuss their interactions with the gut microbiota in the context of homeostasis and pathogenic infections.

Food for thought - ILC metabolism in the context of helminth infections

Helminths are multicellular ancient organisms residing as parasites at mucosal surfaces of their host. Through adaptation and co-evolution with their hosts, helminths have been able to develop tolerance mechanisms to limit inflammation and avoid expulsion. The study of helminth infections as an integral part of tissue immunology allowed us to understand fundamental aspects of mucosal and barrier immunology, which led to the discovery of a new group of tissue-resident immune cells, innate lymphoid cells (ILC), over a decade ago. Here, we review the intricate interplay between helminth infections and type 2 ILC (ILC2) biology, discuss the host metabolic adaptation to helminth infections and the metabolic pathways fueling ILC2 responses. We hypothesize that nutrient competition between host and helminths may have prevented chronic inflammation in the past and argue that a detailed understanding of the metabolic restraints imposed by helminth infections may offer new therapeutic avenues in the future.

Nutritional Interventions and the Gut Microbiome in Children

The gut microbiome plays an integral role in health and disease, and diet is a major driver of its composition, diversity, and functional capacity. Given the dynamic development of the gut microbiome in infants and children, it is critical to address two major questions: (a) Can diet modify the composition, diversity, or function of the gut microbiome, and (b) will such modification affect functional/clinical outcomes including immune function, cognitive development, and overall health? We synthesize the evidence on the effect of nutritional interventions on the gut microbiome in infants and children across 26 studies. Findings indicate the need to study older children, assess the whole intestinal tract, and harmonize methods and interpretation of findings, which are critical for informing meaningful clinical and public health practice. These findings are relevant for precision health, may help identify windows of opportunity for intervention, and may inform the design and delivery of such interventions. Expected final online publication date for the Annual Review of Nutrition, Volume 41 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Intestinal interplay of quorum sensing molecules and human receptors

Human gut is in permanent contact with microorganisms that play an important role in many physiological processes including metabolism and immunologic activity. These microorganisms communicate and manage themself by the quorum sensing system (QS) that helps to coordinate optimal growth and subsistence by activating signaling pathways that regulate bacterial gene expression. Diverse QS molecules produced by pathogenic as well as resident microbiota have been found throughout the human gut. However, even a host can by affected by these molecules. Intestinal and immune cells possess a range of molecular targets for QS. Our present knowledge on bacteria-cell communication encompasses G-protein-coupled receptors, nuclear receptors and receptors for bacterial cell-wall components. The QS of commensal bacteria has been approved as a protective factor with favourable effects on intestinal homeostasis and immunity. Signaling molecules of QS interacting with above-mentioned receptors thus parcipitate on maintaining of barrier functions, control of inflammation processes and increase of resistance to pathogen colonization in host organisms. Pathogens QS molecules can have a dual function. Host cells are able to detect the ongoing infection by monitoring the presence and changes in concentrations of QS molecules. Such information can help to set the most effective immune defence to prevent or overcome the infection. Contrary, pathogens QS signals can target the host receptors to deceive the immune system to get the best conditions for growth. However, our knowledge about communication mediated by QS is still limited and detailed understanding of molecular mechanisms of QS signaling is desired.

Comparative analysis of the gut microbiota of mice fed a diet supplemented with raw and cooked beef loin powder

We used 16S ribosomal RNA sequencing to evaluate changes in the gut microbiota of mice fed a diet supplemented with either raw or cooked beef loin powder for 9 weeks. Male BALB/c mice (n = 60) were randomly allocated to five groups: mice fed AIN-93G chow (CON), chow containing 5% (5RB) and 10% (10RB) raw beef loin powder, and chow containing 5% (5CB) and 10% (10CB) cooked beef loin powder. Dietary supplementation with both RB and CB increased the relative abundance of Clostridiales compared to the CON diet (p < 0.05). Mice fed 10RB showed a significantly higher relative abundance of Firmicutes (p = 0.018) and Lactobacillus (p = 0.001) than CON mice, and the ratio of Firmicutes/Bacteroidetes showed an increasing trend in the 10RB mice (p > 0.05). Mice fed 10CB showed a higher abundance of Peptostreptococcaceae and a lower abundance of Desulfovibrionaceae compared with the CON mice (p < 0.05). Genes for glycan biosynthesis, which result in short-chain fatty acid synthesis, were enriched in the CB mice compared to the RB mice, which was correlated to a high abundance of Bacteroides. Overall, dietary RB and CB changed the gut microbiota of mice (p < 0.05).

Nutrition-Based Management of Inflammaging in CKD and Renal Replacement Therapies

Access to renal transplantation guarantees a substantial improvement in the clinical condition and quality of life (QoL) for end-stage renal disease (ESRD) patients. In recent years, a greater number of older patients starting renal replacement therapies (RRT) have shown the long-term impact of conservative therapies for advanced CKD and the consequences of the uremic milieu, with a frail clinical condition that impacts not only their survival but also limits their access to transplantation. This process, referred to as “inflammaging,” might be reversible with a tailored approach, such as RRT accompanied by specific nutritional support. In this review, we summarize the evidence demonstrating the presence of several proinflammatory substances in the Western diet (WD) and the positive effect of unprocessed food consumption and increased fruit and vegetable intake, suggesting a new approach to reduce inflammaging with the improvement of ESRD clinical status. We conclude that the Mediterranean diet (MD), because of its modulative effects on microbiota and its anti-inflammaging properties, may be a cornerstone in a more precise nutritional support for patients on the waiting list for kidney transplantation.

Induction of AhR transactivation by PBDD/Fs and PCDD/Fs using a novel human-relevant, high-throughput DRhuman CALUX reporter gene assay

Polychlorinated dioxins and dibenzofurans (PCDD/Fs) are highly toxic contaminants that are strictly regulated and monitored in the environment and food to reduce human exposure. Recently, the increasing occurrence of polybrominated dioxins and dibenzofurans (PBDD/Fs) in the environment is raising concerns about the impact on human health by the combined exposure to chlorinated and brominated analogues of dioxins. Toxicological properties of PBDD/Fs relative to PCDD/Fs have not been firmly established, and brominated dioxins are not included in routine monitoring programs. In this study, we set out to determine human-relevant congener-specific potency values for a range of brominated and chlorinated dioxin congeners, based on their aryl hydrocarbon receptor (AhR)-mediated mode of toxic action. Transactivation of the AhR was measured using dioxin-responsive (DR) CALUX reporter gene assays. Because of known species-differences in dioxin-mediated toxicity, we developed and used a HepG2 human liver cell-based DR human CALUX assay that is a variant of the rodent-based DR CALUX. The assay was found to be highly inducible and stable, with low variations between independent measurements. Using both DR CALUX assays in an automated high-throughput mode we found that overall PBDD/Fs were as potent as PCDD/Fs in inducing AhR transactivation, but congener-specific differences were observed. We also observed species-specific differences in sensitivity and potency when comparing DR human REP values to those obtained in the rat-based DR CALUX. Finally, we observed significant differences between WHO-TEF values and DR human REP values, suggesting that actual WHO-TEF values may underestimate the hazards associated with exposure of humans to dioxins.

MAIT Cells in Barrier Tissues: Lessons from Immediate Neighbors

Mucosal-associated invariant T (MAIT) cells are innate-like T cells present at considerable frequencies in human blood and barrier tissues, armed with an expanding array of effector functions in response to homeostatic perturbations. Analogous to other barrier immune cells, their phenotype and function is driven by crosstalk with host and dynamic environmental factors, most pertinently the microbiome. Given their distribution, they must function in diverse extracellular milieus. Tissue-specific and adapted functions of barrier immune cells are shaped by transcriptional programs and regulated through a blend of local cellular, inflammatory, physiological, and metabolic mediators unique to each microenvironment. This review compares the phenotype and function of MAIT cells with other barrier immune cells, highlighting potential areas for future exploration. Appreciation of MAIT cell biology within tissues is crucial to understanding their niche in health and disease.

Dietary cellulose induces anti-inflammatory immunity and transcriptional programs via maturation of the intestinal microbiota

Although it is generally accepted that dietary fiber is health promoting, the underlying immunological and molecular mechanisms are not well defined, especially with respect to cellulose, the most ubiquitous dietary fiber. Here, the impact of dietary cellulose on intestinal microbiota, immune responses and gene expression in health and disease was examined. Lack of dietary cellulose disrupted the age-related diversification of the intestinal microbiota, which subsequently remained in an immature state. Interestingly, one of the most affected microbial genera was Alistipes which is equipped with enzymes to degrade cellulose. Absence of cellulose changed the microbial metabolome, skewed intestinal immune responses toward inflammation, altered the gene expression of intestinal epithelial cells and mice showed increased sensitivity to colitis induction. In contrast, mice with a defined microbiota including A. finegoldii showed enhanced colonic expression of intestinal IL-22 and Reg3γ restoring intestinal barrier function. This study supports the epidemiological observations and adds a causal explanation for the health promoting effects of the most common biopolymer on earth.

A CRISPR/Cas9 Whole-Genome Screen Identifies Genes Required for Aryl Hydrocarbon Receptor-Dependent Induction of Functional CYP1A1

Environmental pollutants including halogenated aromatic hydrocarbons and polycyclic aromatic hydrocarbons, including benzo[a]pyrene, exert their deleterious effects through the activation of the aryl hydrocarbon receptor (AHR) and by the resulting transcription of genes not yet fully identified. Ligand-bound AHR translocates from cytoplasm to nucleus, where it dimerizes with the aryl hydrocarbon receptor nuclear translocator (ARNT) protein. The AHR/ARNT dimer binds to enhancer regions of responsive genes to activate transcription. AHR also mediates carcinogenesis caused by PAHs, likely via CYP1A1, CYP1A2, and CYP1B1, which are massively induced by activated AHR in many tissues and generate carcinogenic electrophilic derivatives of PAHs. In the current study, we have used the mouse GeCKOv2 genome-wide CRISPR/Cas9 library to identify novel genes in the AHR pathway by taking advantage of a B[a]P selection assay that we previously used to identify core AHR pathway genes in Hepa-1c1c7 murine hepatoma cells. Besides Ahr, Arnt, and Cyp1a1, we report the identification of multiple additional putative AHR pathway genes including several that we validated. These include cytochrome P450 reductase (Por), which mediates redox regeneration of cytochromes P450, and 5 genes of the heme biosynthesis pathway: delta-aminolevulinate synthase 1 (Alas1), porphobilinogen deaminase (Hmbs), uroporphyrinogen decarboxylase (Urod), coproporphyrinogen oxidase (Cpox), and ferrochelatase (Fech): heme being an essential prosthetic group of cytochrome P450 proteins. Notably, several of these genes were identified by GeCKO screening, despite not being identifiable by reverse genetics approaches. This indicates the power of high-sensitivity genome-wide genetic screening for identifying genes in the AHR pathway.

Dietary Glucose Consumption Promotes RALDH Activity in Small Intestinal CD103+CD11b+ Dendritic Cells

Retinal dehydrogenase (RALDH) enzymatic activities catalyze the conversion of vitamin A to its metabolite Retinoic acid (RA) in intestinal dendritic cells (DCs) and promote immunological tolerance. However, precise understanding of the exogenous factors that act as initial trigger of RALDH activity in these cells is still evolving. By using germ-free (GF) mice raised on an antigen free (AF) elemental diet, we find that certain components in diet are critically required to establish optimal RALDH expression and activity, most prominently in small intestinal CD103⁺CD11b⁺ DCs (siLP-DCs) right from the beginning of their lives. Surprisingly, systematic screens using modified diets devoid of individual dietary components indicate that proteins, starch and minerals are dispensable for this activity. On the other hand, in depth comparison between subtle differences in dietary composition among different dietary regimes reveal that adequate glucose concentration in diet is a critical determinant for establishing RALDH activity specifically in siLP-DCs. Consequently, pre-treatment of siLP-DCs, and not mesenteric lymph node derived MLNDCs with glucose, results in significant enhancement in the in vitro generation of induced Regulatory T (iTreg) cells. Our findings reveal previously underappreciated role of dietary glucose concentration in establishing regulatory properties in intestinal DCs, thereby extending a potential therapeutic module against intestinal inflammation.

Quercetin induces an immunoregulatory phenotype in maturing human dendritic cells

The aryl hydrocarbon receptor (AhR) is an environmental sensor and ligand-activated transcription factor that is critically involved in the regulation of inflammatory responses and the induction of tolerance by modulating immune cells. As dendritic cells (DCs) express high AhR levels, they are efficient to induce immunomodulatory effects after being exposed to AhR-activating compounds derived from the environment or diet. To gain new insights into the molecular targets following AhR-activation in human monocyte-derived (mo)DCs, we investigated whether the natural AhR ligand quercetin or the synthetic ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) modulates the function of human moDCs regarding their capability to prime naïve T cells or to migrate. As only quercetin, but not TCDD, impaired T cell activation and migration of LPS-matured DCs (LPS-DCs), we analyzed the mode of action of quercetin on moDCs in more detail. Here, we found a specific down-regulation of the immunomodulatory molecule CD83 through the direct binding of the activated AhR to the CD83 promoter. Furthermore, treatment of LPS-DCs with quercetin resulted in a reduced production of the pro-inflammatory cytokine IL-12p70 and in an increased expression of the immunoregulatory molecules disabled adaptor protein (Dab) 2, immunoglobulin-like transcript (ILT)-3, ILT4, ILT5 as well as ectonucleotidases CD39 and CD73, thereby inducing a tolerogenic phenotype in quercetin-treated maturing DCs. Overall, these data demonstrate that quercetin represents a potent immunomodulatory agent to alter human DC phenotype and function, shifting the immune balance from inflammation to resolution.

Switching to a Healthy Diet Prevents the Detrimental Effects of Western Diet in a Colitis-Associated Colorectal Cancer Model

Inflammatory bowel disease increases the odds of developing colitis-associated cancer. We hypothesized that Western-style diet (WD) aggravates azoxymethane (AOM)/dextran sulfate sodium salt (DSS)-induced colitis-associated tumorigenesis and that switching to the standard AIN93G diet will ameliorate disease symptoms even after cancer initiation. Female BALB/c mice received either WD (WD group) or standard AIN93G diet (AIN group) for the whole experimental period. After five weeks, the mice received 12.5 mg/kg AOM intraperitoneally, followed by three DSS cycles. In one group of mice, the WD was switched to AIN93G the day before starting the first DSS cycle (WD/AIN group). Feeding the WD during the whole experimental period aggravated colitis symptoms, shortened the colon (p < 0.05), changed microbiota composition and increased tumor promotion. On molecular level, the WD reduced proliferation (p < 0.05) and increased expression of the vitamin D catabolizing enzyme Cyp24a1 (p < 0.001). The switch to the AIN93G diet ameliorated this effect, reflected by longer colons, fewer (p < 0.05) and smaller (p < 0.01) aberrant colonic crypt foci, comparable with the AIN group. Our results show that switching to a healthy diet, even after cancer initiation is able to revert the deleterious effect of the WD and could be an effective preventive strategy to reduce colitis symptoms and prevent tumorigenesis.

Comprehensive and semi-quantitative analysis of carboxyl-containing metabolites related to gut microbiota on chronic kidney disease using 2-picolylamine isotopic labeling LC-MS/MS

Carboxyl-containing metabolites, such as bile acids and fatty acids, have many important functions and microbiota is involved in the production of them. In the previous study, we found that the chronic kidney disease (CKD) model mice raised under germ-free conditions provided more severe renal damage than the mice with commensal microbiota. However, the precise influence by the microbiome and carboxyl-containing metabolites to the renal functions is unknown. In this study, we aimed to develop a novel chemical isotope labeling-LC-MS/MS method using the 2-picolylamine and its isotopologue and applied the analysis of effects of microbiome and CKD pathophysiology. The developed semi-quantitative method provided the high accuracy not inferior to the absolute quantification. By comparing of four groups of mice, we found that both microbiota and renal function can alter the composition and level of these metabolites in both plasma and intestine. In particular, the intestinal level of indole-3-acetic acid, short-chain fatty acids and n-3 type of polyunsaturated fatty acid, which play important roles in the endothelial barrier function, were significantly lower in germ-free conditions mice with renal failure. Accordingly, it is suggested these metabolites might have a renoprotective effect on CKD by suppressing epithelial barrier disruption.

The Microbial Pecking Order: Utilization of Intestinal Microbiota for Poultry Health

The loss of antibiotics as a tool to improve feed efficiency in poultry production has increased the urgency to understand how the microbiota interacts with animals to impact productivity and health. Modulating and harnessing microbiota-host interactions is a promising way to promote poultry health and production efficiencies without antibiotics. In poultry, the microbiome is influenced by many host and external factors including host species, age, gut compartment, diet, and environmental exposure to microbes. Because so many factors contribute to the microbiota composition, specific knowledge is needed to predict how the microbiome will respond to interventions. The effects of antibiotics on microbiomes have been well documented, with different classes of antibiotics having distinctive, specific outcomes on bacterial functions and membership. Non-antibiotic interventions, such as probiotics and prebiotics, target specific bacterial taxa or function to enhance beneficial properties of microbes in the gut. Beneficial bacteria provide a benefit by displacing pathogens and/or producing metabolites (e.g., short chain fatty acids or tryptophan metabolites) that promote poultry health by improving mucosal barrier function or immune function. Microbiota modulation has been used as a tool to reduce pathogen carriage, improve growth, and modulate the immune system. An increased understanding of how the microbiota interacts with animal hosts will improve microbiome intervention strategies to mitigate production losses without the need for antibiotics.

SARI attenuates colon inflammation by promoting STAT1 degradation in intestinal epithelial cells

SARI functions as a suppressor of colon cancer and predicts survival of colon cancer patients, but its role in regulating colitis has not been characterized. Here we show that SARI^-/- mice were highly susceptible to colitis, which was associated with enhanced macrophage infiltration and inflammatory cytokine production. Bone marrow reconstitution experiments demonstrated that disease susceptibility was not dependent on the deficiency of SARI in the immune compartment but on the protective role of SARI in the intestinal epithelial cells (IECs). Furthermore, SARI deficiency enhanced Chemokine (C-C motif) Ligand 2 (CCL2) production and knockout of CCR2 blocks the promoting role of SARI deficiency on colitis. Mechanistically, SARI directly targets and promotes signal transducer and activator of transcription 1 (STAT1) degradation in IECs, followed by persistent inactivation of the STAT1/CCL2 transcription complex. In summary, SARI attenuated colitis in mice by impairing colitis-dependent STAT1/CCL2 transcriptional activation in IECs and macrophages recruitment in colon tissue.

Role for diet in normal gut barrier function: developing guidance within the framework of food-labeling regulations

A reduction in intestinal barrier function is currently believed to play an important role in pathogenesis of many diseases, as it facilitates passage of injurious factors such as lipopolysaccharide, peptidoglycan, whole bacteria, and other toxins to traverse the barrier to damage the intestine or enter the portal circulation. Currently available evidence in animal models and in vitro systems has shown that certain dietary interventions can be used to reinforce the intestinal barrier to prevent the development of disease. The relevance of these studies to human health is unknown. Herein, we define the components of the intestinal barrier, review available modalities to assess its structure and function in humans, and review the available evidence in model systems or perturbations in humans that diet can be used to fortify intestinal barrier function. Acknowledging the technical challenges and the present gaps in knowledge, we provide a conceptual framework by which evidence could be developed to support the notion that diet can reinforce human intestinal barrier function to restore normal function and potentially reduce the risk for disease. Such evidence would provide information on the development of healthier diets and serve to provide a framework by which federal agencies such as the US Food and Drug Administration can evaluate evidence linking diet with normal human structure/function claims focused on reducing risk of disease in the general public.

Candida albicans at Host Barrier Sites: Pattern Recognition Receptors and Beyond

Over the last decades, fungal infections have emerged as a growing threat to human health. Although the human body is at potential risk, various body sites host several commensal fungal species, including Candida albicans. In healthy individuals, C. albicans colonizes different mucosal surfaces without causing harm, while under diverse circumstances the fungus can proliferate and cause disease. In this context, the understanding of host⁻C. albicans interactions in health and during infection may lead to novel therapeutic approaches. Importantly, host cells express pattern recognition receptors (PRRs), which sense conserved fungal structures and orchestrate innate immune responses. Herein, important findings on the topic of the recognition of C. albicans at host barrier sites are discussed. This review briefly summarizes the importance and functions of myeloid PRRs, reviews the fungal recognition and biology of stromal cells, and highlights important C. albicans virulence attributes during site-specific proliferation and invasion.

Neonatal intestinal immune regulation by the commensal bacterium, P. UF1

Newborns are highly susceptible to pathogenic infections with significant worldwide morbidity possibly due to an immature immune system. Recently, we reported that Propionibacterium strain, P. UF1, isolated from the gut microbiota of preterm infants, induced the differentiation of bacteria-specific Th17 cells. Here, we demonstrate that P. UF1 significantly increased the number of protective Th17 cells and maintained IL-10⁺ regulatory T cells (Tregs) in newborn mice. In addition, P. UF1 protected mice from intestinal Listeria monocytogenes (L. m) infection. P. UF1 also functionally sustained the gut microbiota and induced critical B vitamin metabolites implicated in the regulation of T cell immunity during L. m intestinal infection. Transcriptomic analysis of P. UF1-induced Th17 cells revealed genes involved in the differentiation and regulation of these cells. These results illustrate the potency of P. UF1 in the enhancement of neonatal host defense against intestinal pathogen infection.

Circulating Vitamin D and Colorectal Cancer Risk: An International Pooling Project of 17 Cohorts

BACKGROUND

Experimental and epidemiological studies suggest a protective role for vitamin D in colorectal carcinogenesis, but evidence is inconclusive. Circulating 25-hydroxyvitamin D (25(OH)D) concentrations that minimize risk are unknown. Current Institute of Medicine (IOM) vitamin D guidance is based solely on bone health.

METHODS

We pooled participant-level data from 17 cohorts, comprising 5706 colorectal cancer case participants and 7107 control participants with a wide range of circulating 25(OH)D concentrations. For 30.1% of participants, 25(OH)D was newly measured. Previously measured 25(OH)D was calibrated to the same assay to permit estimating risk by absolute concentrations. Study-specific relative risks (RRs) for prediagnostic season-standardized 25(OH)D concentrations were calculated using conditional logistic regression and pooled using random effects models.

RESULTS

Compared with the lower range of sufficiency for bone health (50-<62.5 nmol/L), deficient 25(OH)D (<30 nmol/L) was associated with 31% higher colorectal cancer risk (RR = 1.31, 95% confidence interval [CI] = 1.05 to 1.62); 25(OH)D above sufficiency (75-<87.5 and 87.5-<100 nmol/L) was associated with 19% (RR = 0.81, 95% CI = 0.67 to 0.99) and 27% (RR = 0.73, 95% CI = 0.59 to 0.91) lower risk, respectively. At 25(OH)D of 100 nmol/L or greater, risk did not continue to decline and was not statistically significantly reduced (RR = 0.91, 95% CI = 0.67 to 1.24, 3.5% of control participants). Associations were minimally affected when adjusting for body mass index, physical activity, or other risk factors. For each 25 nmol/L increment in circulating 25(OH)D, colorectal cancer risk was 19% lower in women (RR = 0.81, 95% CI = 0.75 to 0.87) and 7% lower in men (RR = 0.93, 95% CI = 0.86 to 1.00) (two-sided Pheterogeneity by sex = .008). Associations were inverse in all subgroups, including colorectal subsite, geographic region, and season of blood collection.

CONCLUSIONS

Higher circulating 25(OH)D was related to a statistically significant, substantially lower colorectal cancer risk in women and non-statistically significant lower risk in men. Optimal 25(OH)D concentrations for colorectal cancer risk reduction, 75-100 nmol/L, appear higher than current IOM recommendations.

Vitamin D status after colorectal cancer diagnosis and patient survival according to immune response to tumour

BACKGROUND

High-level plasma 25-hydroxyvitamin D [25(OH)D] has been associated with lower colorectal cancer incidence and mortality. Considering evidence indicating immunomodulatory effects of vitamin D, we hypothesised that survival benefits from high systemic vitamin D level might be stronger for colorectal carcinoma with lower immune response to tumour.

METHODS

Using 869 colon and rectal cancer cases within the Nurses' Health Study and Health Professionals Follow-up Study, we assessed the prognostic association of postdiagnosis 25(OH)D score [derived from diet and lifestyle variables to predict plasma 25(OH)D level] in strata of levels of histopathologic lymphocytic reaction. The Cox proportional hazards regression model was adjusted for potential confounders, including microsatellite instability, CpG island methylator phenotype, LINE-1 methylation, PTGS2 (cyclooxygenase-2) expression and KRAS, BRAF and PIK3CA mutations.

RESULTS

The association of postdiagnosis 25(OH)D score with colorectal cancer-specific mortality differed by levels of peritumoural lymphocytic reaction (pinteraction = 0.001). Multivariable-adjusted mortality hazard ratios for a quintile-unit increase of 25(OH)D score were 0.69 [95% confidence interval (CI), 0.54-0.89] in cases with negative/low peritumoural lymphocytic reaction, 1.08 (95% CI, 0.93-1.26) in cases with intermediate peritumoural reaction and 1.25 (95% CI, 0.75-2.09) in cases with high peritumoural reaction. The survival association of the 25(OH)D score did not significantly differ by Crohn's-like lymphoid reaction, intratumoural periglandular reaction or tumour-infiltrating lymphocytes.

CONCLUSIONS

The association between the 25(OH)D score and colorectal cancer survival is stronger for carcinomas with lower peritumoural lymphocytic reaction. Our results suggesting interactive effects of vitamin D and immune response may contribute to personalised dietary and lifestyle intervention strategies.

Effects of chronic dexamethasone exposure on bile acid metabolism and cecal epithelia function in goats

Bile acids (BAs) are synthesized in the liver via the oxidation of cholesterol and further metabolized by microbiota in the gut, where they simultaneously impact gut function. In the present study, 10 goats were randomly divided into 2 groups; 1 group was injected with dexamethasone (Dex; 0.2 mg/kg), and the other group was injected with saline as the control (Con) for 21 d. Expression levels of key genes and proteins in the liver and gut mucosa were analyzed and compared to investigate the impact of chronic stress on BA metabolism and related functions in ruminants. The results revealed that Dex decreased plasma total BAs (TBAs) concentration (P < 0.05) but increased TBA concentration in the cecal digesta (P < 0.05). Total cholesterol in the liver decreased moderately in response to Dex. The protein expression of cytochrome P450 family 7 subfamily A member 1 and cytochrome P450 family 27 subfamily A member 1, 2 enzymes that control BA synthesis in the liver, remained unchanged by Dex administration (P > 0.05). The expression of several genes in the cecal mucosa encoding epithelial tight junction proteins, including occludin (P < 0.05), tight junction protein 1 (P < 0.01), and claudin 1 (P < 0.05), increased significantly in response to Dex, and expression of defensin beta 1, which can strengthen the innate immune system, was also upregulated (P < 0.05). In addition, BAs increased the expression of the Solute Carrier family 9 member A 2 (P < 0.01) that encodes a sodium hydrogen exchanger. These results suggest that the Dex-induced disruption of BA homeostasis might be mediated through a liver-independent pathway in goats, and the Dex-induced accumulation of TBAs in the cecal digesta may improve volatile fatty acid transportation and mucosal defense.

Effects of Metabolites Derived From Gut Microbiota and Hosts on Pathogens

Intestinal metabolites participate in various physiological processes, including energy metabolism, cell-to-cell communication, and host immunity. These metabolites mainly originate from gut microbiota and hosts. Although many host metabolites are dominant in intestines, such as free fatty acids, amino acids and vitamins, the metabolites derived from gut microbiota are also essential for intestinal homeostasis. In addition, some metabolites are only generated and released by gut microbiota, such as bacteriocins, short-chain fatty acids, and quorum-sensing autoinducers. In this review, we summarize recent studies regarding the crosstalk between pathogens and metabolites from different sources, including the influence on bacterial development and the activation/inhibition of immune responses of hosts. All of these functions would affect the colonization of and infection by pathogens. This review provides clear ideas and directions for further exploring the regulatory mechanisms and effects of metabolites on pathogens.

Metabolic wiring of murine T cell and intraepithelial lymphocyte maintenance and activation

Adaptive immunity critically depends on cell migration combined with clonal selection and rapid expansion of rare lymphocytes recognising their cognate antigen in secondary lymphoid organs. It has since become apparent that large populations of T cells are maintained in tissues, which do not migrate throughout the body and do not require clonal expansion. Murine intraepithelial lymphocytes (IELs), located in the skin and small intestines, are maintained in a state of semi-activation, in marked contrast to the quiescent condition naive and memory lymphocytes are kept in. The poised activation state of IELs, their location in the top layers of barrier organs and close bidirectional interactions with epithelial cells suggests IELs are part of a sophisticated strategy of immune-surveillance and compartmentalisation of immune responses. Recent murine studies have reemphasised the influence of metabolism in T-cell activation and differentiation, with different metabolic make up of naive, effector and memory T cells. Here we highlight and discuss some of the current insights on immunometabolism of IELs, with emphasis on novel data contrasting how IELs may be maintained in a semi-activated state and may become fully functional compared with conventional T cells.

The functionality of prebiotics as immunostimulant: Evidences from trials on terrestrial and aquatic animals

The gut immune system is, the main option for maintaining host's health, affected by numerous factors comprising dietary constituents and commensal bacteria. These dietary components that affect the intestinal immunity and considered as an alternative of antibiotics are called immunosaccharides. Fructooligosaccharide (FOS), Galactooligosaccharide (GOS), inulin, dietary carbohydrates, and xylooligosaccharide (XOS) are among the most studied prebiotics in human as well as in aquaculture. Although prebiotics and probiotics have revealed potential as treatment for numerous illnesses in both human and fish, a comprehensive understanding of the molecular mechanism behind direct and indirect effect on the intestinal immune response will help more and perhaps extra effective therapy intended for ailments. This review covers the most newly deep-rooted scientific outcomes about the direct and indirect mechanism through which these dietetic strategies can affect intestinal immunity of terrestrial and aquatic animals. Prebiotics exert an influence on gut immune system via the increase in lysozyme and phagocytic activity, macrophage activation and stimulation of monocyte-derived dendritic cells. Furthermore, these functional molecules also enhance epithelial barrier function, beneficial gut microbial population, and production of intermediate metabolites for example short chain fatty acids (SCFAs) that assist in balancing the immune system. Moreover, emphasis will be sited on the relationship among food/feed, the microbiota, and the gut immune system. In conclusion, further studies are nonetheless essential to confirm the direct effect of prebiotics on immune response.

Allergic diseases: From bench to clinic - Contribution of the discovery of interleukin-5

T helper 2 cells produce a number of cytokines including inteleukin (IL)-5, IL-4 and IL-13. Group 2 innate lymphoid cells (ILC2s) also produce IL-5 under sterile conditions. IL-5 is interdigitating homodimeric glycoprotein and a member of the four α helical bundle motifs conserved among hematopoietic cytokines. IL-5 exerts its effects on target cells via IL-5 receptor (IL-5R), composed of an IL-5R α and βc subunit. The membrane proximal proline-rich motif of the cytoplasmic domain of both IL-5R α and βc subunits is essential for IL-5 signal transduction. Although IL-5 was initially identified by its ability to support the growth and terminal differentiation of mouse B cells into antibody-secreting cells, recombinant IL-5 exerts pleiotropic activities on various target cells. For example, IL-5 is now recognized as the major maturation and differentiation factor for eosinophils in mice and humans. Overexpression of IL-5 in mouse significantly increases eosinophil numbers and antibody levels in vivo, while mice lacking a functional gene for IL-5 or IL-5R display developmental and functional impairments in B cell and eosinophil lineages. In mice, the role of the IL-5/IL-5R system in the production and secretion of Immunoglobulin (Ig) M and IgA in mucosal tissues has been reported. Although eosinophils protect against invading pathogens including virus, bacteria and helminthes, they are also involved in the pathogenesis of various diseases, such as food allergy, asthma, and inflammatory bowel diseases. The recent expansion in our understanding in the context of IL-5 and IL-5-producing ILC2s in eosinophil activation and the pathogenesis of eosinophil-dependent inflammatory diseases has led to advances in therapeutic options. A new therapy currently under invetigarion in clinical trials uses humanized monoclonal antibodies against IL-5 or the IL-5R. In this review, we summarize our current understanding of the functions of IL-5 and its receptor, the innate regulation of IL-5-producing cells, and therapeutic potential of anti-IL-5 and anti-eosinophil (IL-5R) antibodies.

Th9 Cells: Probable players in ulcerative colitis pathogenesis

T lymphocytes represent an important part of adaptive immune system undertaking different functions to regulate immune responses. CD4+ T cells are the most important activator cells in inflammatory conditions. Depending on the type of induced cells and inflamed sites, expression and activity of different subtypes of helper T cells are changed. Recent studies have confirmed the existence of a new subset of helper T lymphocytes called Th9. Naive T cells can differentiate into Th9 subtypes if they are exposed simultaneously by interleukin (IL) 4 and transforming growth factor β and also secondary activation of a complicated network of transcription factors such as interferon regulatory factor 4 (IRF4) and Smads which are essential for adequate induction of this phenotype. Th9 cells specifically produce interleukin 9 and their probable roles in promoting intestinal inflammation are being investigated in human subjects and experimental models of ulcerative colitis (UC). Recently, infiltration of Th9 cells, overexpression of IL-9, and certain genes associated with Th9 differentiation have been demonstrated in inflammatory microenvironment of UC. Intestinal oversecretion of IL-9 protein is likely to break down epithelial barriers and compromise tolerance to certain commensal microorganisms which leads to inflammation. Th9 pathogenicity has not yet been adequately explored in UC and they are far from being considered as inflammatory cells in this milieu, therefore precise understanding the role of these newly identified cells in particular their potential role in gut pathogenesis may enable us to develop novel therapeutic approaches for inflammatory bowel disease. So, this article tries to discuss the latest knowledge on the above-mentioned field.

Origins and evolution of innate lymphoid cells: Wardens of barrier immunity

The identification, in the late 2000s, of innate lymphoid cells (ILCs) as a new class of non-B, non-T lymphocytes has led to global efforts to understand their functions, plasticity and evolutionary origins and to define their place within the leucocyte family. Although this work has uncovered striking similarities in the developmental cues, lineage-specific transcription factors and functional capacities of innate and adaptive lymphocytes, it has become clear that ILCs play a unique and defining role as stewards of barrier defence and that this sets them apart from their adaptive cousins. This review will explore how the dynamic environment of barrier surfaces has shaped ILC evolution and functionality. We highlight the critical importance of the microbiome and the unique role of ILCs as environmental sensors. We reflect on how these factors may have influenced the development of ILC2s and barrier immunity in the context of exposure to helminth parasites that have been driving forces of our evolution throughout human history. Finally, we argue that the plasticity of ILC function reflects their role as first responders to environmental change.

Metabolic Regulation of Innate Lymphoid Cell-Mediated Tissue Protection-Linking the Nutritional State to Barrier Immunity

Innate lymphoid cells (ILC) are a recently described group of tissue-resident immune cells that play essential roles in maintaining and protecting the tissue barrier against invading pathogens. Extensive research has revealed that ILC-mediated immune responses are controlled by dietary components and metabolites. An additional role of ILC as important direct regulators of host metabolism and glucose tolerance is emerging. This suggests that ILC may act as key dietary sensors integrating nutritional and metabolic stress to facilitate both maintenance of barrier sites and a coordinated immune response protecting these tissues. In this respect, investigations have begun to determine how different ILC responses are metabolically fueled and the impact of nutrient availability on the regulation of ILC function. Here, we discuss the current literature concerning dietary and metabolic control of ILC. In particular, we address whether the dietary and metabolic control of ILC and their simultaneous influence on host metabolism may function as a coordinated program of barrier defense.