Lamina Propria Of Small Intestine Research Articles

Maternal consumption of yoghurt activating the aryl hydrocarbon receptor increases group 3 innate lymphoid cells in murine offspring

ABSTRACT Indole derivatives are microbial metabolites of the tryptophan pathway involved in gut immune homeostasis. They bind to the aryl hydrocarbon receptor (AhR), thereby modulating development of intestinal group 3 innate lymphoid cells (ILC3) and subsequent interleukin-22 production. In mice, indole derivatives of the maternal microbiota can reach the milk and drive early postnatal ILC3 development. Apart from the gut microbiota, lactic acid bacteria (LAB) also produce indole compounds during milk fermentation. Using germ-free mice, the aim of our study was to test if maternal intake of a dairy product enriched in AhR-activating indoles produced by fermentation could boost maturation of the intestinal innate immune system in the offspring. A set of 631 LAB strains were genetically screened for their potential to produce indole compounds. Among these, 125 strains were tested in combination with standard strains to produce yoghurts that were screened for their ability to activate AhR in vitro using the HepG2–AhR–Luc cell line. The most active yoghurt and a control yoghurt were formulated as pellets and fed to germ-free dams during pregnancy and lactation. Analysis of the offspring on postnatal day 14 using flow cytometry revealed an increase in the frequency of small intestinal lamina propria NKp46 +ILC3 s in the pups born to dams that had consumed the purified diet containing an AhR-active yoghurt (AhrY-diet) compared to control yoghurt (ConY-diet). Selection of LABs based on their ability to produce a fermented dairy able to activate AhR appears to be an effective approach to produce a yoghurt with immunomodulatory properties. IMPORTANCE Key progresses in the sequencing and functional annotation of microbial organisms have revolutionized research in the fields of human metabolism and food biotechnology. In particular, the gut microbiome is now recognized as an important mediator of the impact of nutrition on human metabolism. Annotated genomes of a large number of bacteria are now available worldwide, which selectively transform food through fermentation to produce specific bioactive compounds with the potential to modulate human health. A previous research has demonstrated that the maternal microbiota shapes the neonatal immune system. Similarly, this report shows that lactic acid bacteria can be selected to produce fermented food that can also modulate postnatal intestinal immunity.

TCF-1 and TOX regulate the memory formation of intestinal group 2 innate lymphoid cells in asthma

Immune memory has been expanded to group 2 innate lymphoid cells (ILC2s), but the cellular and molecular bases remain incompletely understood. Based on house dust mite (HDM)-induced mice asthma models and human samples, we applied flow cytometry, parabiosis, in vivo imaging and adoptive transplantation to confirm the persistence, migration and function of CD45+lineage–CD90.2+NK1.1–NKp46–ST2–KLRG1+IL-17RB+ memory-like ILC2s (ml-ILC2s). Regulated by CCR9/CCL25 and S1P signaling, ml-ILC2s reside in the lamina propria of small intestines (siLP) in asthma remission, and subsequently move to airway upon re-encountering antigens or alarmins. Furthermore, ml-ILC2s possess properties of longevity, potential of rapid proliferation and producing IL-13, and display transcriptional characteristics with up-regulation of Tox and Tcf-7. ml-ILC2s transplantation restore the asthmatic changes abrogated by Tox and Tcf7 knockdown. Our data identify siLP ml-ILC2s as a memory-like subset, which promotes asthma relapse. Targeting TCF-1 and TOX might be promising for preventing asthma recurrence.

Recipient tissue microenvironment determines developmental path of intestinal innate lymphoid progenitors

Innate lymphoid cells (ILCs) are critical in maintaining tissue homeostasis, and during infection and inflammation. Here we identify, by using combinatorial reporter mice, a rare ILC progenitor (ILCP) population, resident to the small intestinal lamina propria (siLP) in adult mice. Transfer of siLP-ILCP into recipients generates group 1 ILCs (including ILC1 and NK cells), ILC2s and ILC3s within the intestinal microenvironment, but almost exclusively group 1 ILCs in the liver, lung and spleen. Single cell gene expression analysis and high dimensional spectral cytometry analysis of the siLP-ILCPs and ILC progeny indicate that the phenotype of the group 1 ILC progeny is also influenced by the tissue microenvironment. Thus, a local pool of siLP-ILCP can contribute to pan-ILC generation in the intestinal microenvironment but has more restricted potential in other tissues, with a greater propensity than bone marrow-derived ILCPs to favour ILC1 and ILC3 production. Therefore, ILCP potential is influenced by both tissue of origin and the microenvironment during development. This may provide additional flexibility during the tuning of immune reactions.

The kynurenine pathway regulated by intestinal innate lymphoid cells mediates postoperative cognitive dysfunction

Postoperative cognitive dysfunction (POCD) is a prevalent neurological complication that can impair learning and memory for days, months, or even years after anesthesia/surgery. POCD is strongly associated with an altered composition of the gut microbiota (dysbiosis), but the accompanying metabolic changes and their role in gut–brain communication and POCD pathogenesis remain unclear. Here, the present study reports that anesthesia/surgery in aged mice induces elevated intestinal indoleamine 2,3-dioxygenase (IDO) expression and activity, which shifts intestinal tryptophan (TRP) metabolism toward more IDO-catalyzed kynurenine (KYN) and less gut bacteria-catabolized indoleacetic acid (IAA). Both anesthesia/surgery and intraperitoneal KYN administration induce increased KYN levels that correlate with impaired spatial learning and memory, whereas dietary IAA supplementation attenuates the anesthesia/surgery-induced cognitive impairment. Mechanistically, anesthesia/surgery increases interferon-γ (IFN-γ)-producing group 1 innate lymphoid cells (ILC1) in the small intestine lamina propria and elevates intestinal IDO expression and activity, as indicated by the higher ratio of KYN to TRP. The IDO inhibitor 1-MT and antibodies targeting IFN-γ or ILCs mitigate anesthesia/surgery-induced cognitive dysfunction, suggesting that intestinal ILC1 expansion and the ensuing IFN-γ-induced IDO upregulation may be the primary pathway mediating the shift to the KYN pathway in POCD. The ILC1–KYN pathway in the intestine could be a promising therapeutic target for POCD.

Microbiota-induced plastic T cells enhance immune control of antigen-sharing tumors.

Therapies that harness the immune system to target and eliminate tumor cells have revolutionized cancer care. Immune checkpoint blockade (ICB), which boosts the anti-tumor immune response by inhibiting negative regulators of T cell activation1-3, is remarkably successful in a subset of cancer patients, yet a significant proportion do not respond to treatment, emphasizing the need to understand factors influencing the therapeutic efficacy of ICB4-9. The gut microbiota, consisting of trillions of microorganisms residing in the gastrointestinal tract, has emerged as a critical determinant of immune function and response to cancer immunotherapy, with multiple studies demonstrating association of microbiota composition with clinical response10-16. However, a mechanistic understanding of how gut commensal bacteria influence the efficacy of ICB remains elusive. Here we utilized a gut commensal microorganism, segmented filamentous bacteria (SFB), which induces an antigen-specific Th17 cell effector program17, to investigate how colonization with it affects the efficacy of ICB in restraining distal growth of tumors sharing antigen with SFB. We find that anti-PD-1 treatment effectively inhibits the growth of implanted SFB antigen-expressing melanoma only if mice are colonized with SFB. Through T cell receptor clonal lineage tracing, fate mapping, and peptide-MHC tetramer staining, we identify tumor-associated SFB-specific Th1-like cells derived from the homeostatic Th17 cells induced by SFB colonization in the small intestine lamina propria. These gut-educated ex-Th17 cells produce high levels of the pro-inflammatory cytokines IFN-γ and TNF-α, and promote expansion and effector functions of CD8+ tumor-infiltrating cytotoxic lymphocytes, thereby controlling tumor growth. A better understanding of how distinct intestinal commensal microbes can promote T cell plasticity-dependent responses against antigen-sharing tumors may allow for the design of novel cancer immunotherapeutic strategies.

CD71 + erythroid cells promote intestinal symbiotic microbial communities in pregnancy and neonatal period

BackgroundThe establishment of microbial communities in neonatal mammals plays a pivotal role in shaping their immune responses to infections and other immune-related conditions. This process is influenced by a combination of endogenous and exogenous factors. Previously, we reported that depletion of CD71 + erythroid cells (CECs) results in an inflammatory response to microbial communities in newborn mice.ResultsHere, we systemically tested this hypothesis and observed that the small intestinal lamina propria of neonatal mice had the highest frequency of CECs during the early days of life. This high abundance of CECs was attributed to erythropoiesis niches within the small intestinal tissues. Notably, the removal of CECs from the intestinal tissues by the anti-CD71 antibody disrupted immune homeostasis. This disruption was evident by alteration in the expression of antimicrobial peptides (AMPs), toll-like receptors (TLRs), inflammatory cytokines/chemokines, and resulting in microbial dysbiosis. Intriguingly, these alterations in microbial communities persisted when tested 5 weeks post-treatment, with a more notable effect observed in female mice. This illustrates a sex-dependent association between CECs and neonatal microbiome modulation. Moreover, we extended our studies on pregnant mice, observing that modulating CECs substantially alters the frequency and diversity of their microbial communities. Finally, we found a significantly lower proportion of CECs in the cord blood of pre-term human newborns, suggesting a potential role in dysregulated immune responses to microbial communities in the gut.ConclusionsOur findings provide novel insights into pivotal role of CECs in immune homeostasis and swift adaptation of microbial communities in newborns. Despite the complexity of the cellular biology of the gut, our findings shed light on the previously unappreciated role of CECs in the dialogue between the microbiota and immune system. These findings have significant implications for human health.9S5HPFpJwLA9vyqyoAGSTRVideo

Allergen-Encapsulating Nanoparticles Reprogram Pathogenic Allergen-Specific Th2 Cells to Suppress Food Allergy.

Food allergy is a prevalent, potentially deadly disease caused by inadvertent sensitization to benign food antigens. Pathogenic Th2 cells are a major driver for disease, and allergen-specific immunotherapies (AIT) aim to increase the allergen threshold required to elicit severe allergic symptoms. However, the majority of AIT approaches require lengthy treatments and convey transient disease suppression, likely due to insufficient targeting of pathogenic Th2 responses. Here, the ability of allergen-encapsulating nanoparticles to directly suppress pathogenic Th2 responses and reactivity is investigated in a mouse model of food allergy. NPs associate with pro-tolerogenic antigen presenting cells, provoking accumulation of antigen-specific, functionally suppressive regulatory T cells in the small intestine lamina propria. Two intravenous doses of allergen encapsulated in poly(lactide-co-glycolide) nanoparticles (NPs) significantly reduces oral food challenge (OFC)-induced anaphylaxis. Importantly, NP treatment alters the fates of pathogenic allergen-specific Th2 cells, reprogramming these cells toward CD25+FoxP3+ regulatory and CD73+FR4+ anergic phenotypes. NP-mediated reductions in the frequency of effector cells in the gut and mast cell degranulation following OFC are also demonstrated. These studies reveal mechanisms by which an allergen-encapsulating NP therapy and, more broadly, allergen-specific immunotherapies, can rapidly attenuate allergic responses by targeting pathogenic Th2 cells.

A Role for NOD2 in Intestinal Memory T cell Formation and Function

Abstract Aberrant resident memory T cell (TRM) responses have been associated with increased intestinal inflammation and Crohn’s disease (CD) pathology in humans. Genetic mutations in NOD2 are associated with the highest risk of CD development. NOD2 has been shown to be critical for initiating adaptive immune responses at systemic sites. However, the role of NOD2 in establishing memory T cell responses in the intestine remains unclear. Using an acute model of LCMV infection, we interrogated the role of NOD2 in intestinal memory T cell generation and function. Littermate wildtype or NOD2-deficient mice were infected intraperitoneally with LCMV-Armstrong, and the intestinal T cell priming, effector, and memory T cell responses were profiled in the mesenteric lymph nodes (mLN) and small intestinal lamina propria (SILP). Augmented NOD2 signalling at homeostasis and during infection increased endogenous and LCMV-specific CD4+ T cell numbers in the mLN, but not in the spleen. This effect was due to a NOD2-dependent increase in T cell homing to the mLN. Furthermore, NOD2-deficiency resulted in decreased effector and memory T cell numbers in the SILP. This effect was associated with decreased memory T cell functions in NOD2-deficient mice during ex vivo and in vivo recall experiments. Taken together, our experiments suggest a role for NOD2 in mediating optimal T cell priming in the mesenteric lymph nodes, which later affects effector and memory T cell functions in the intestine.

Early life exposure to Candida albicans disrupts regulatory T cells

Abstract Fungal species are immunogenic members of the commensal microbiota, on the skin and the intestine. Opportunistic Candida albicans is associated with numerous allergic disorders, like atopic dermatitis, with ~90% of cases diagnosed by age 6. With an increased lifetime risk to other allergic disorders, C. albicans exposure in early life may contribute to the development of allergic-type responses. Premature infant stool sequencing found frequent C. albicans colonization suggesting colonization in the human GI tract. Previous observations found mice exposed to C. albicans prior to, but not post, weaning maintain colonization into adulthood. Neonatal colonization of C. albicans in the intestine, resulted in long term colonization and presented significantly decreased FoxP3+ T regulatory cells (Tregs) post-weaning in the mesenteric lymph nodes, small intestine, and colon lamina propria (LP). Additionally, RORγt+ and C-MAF+ Th17-cells were increased in the LP. By comparison, adult exposure to C. albicans through the skin or intestine, showed no disruption of FoxP3+ Tregs, suggesting neonatal exposure to C. albicans may be more disruptive to developing Tregs. Future research will focus on the impact of C. albicans presence to early microbiota complexity and diversity development. Treg establishment in early life is vital for tolerance and maintenance of commensal organisms, thus Treg disruption potentially links C. albicans colonization towards the development of allergic responses.

Polymeric nanoparticles for oral delivery of biopharmaceuticals: an overview

Biopharmaceuticals, cutting-edge medications sourced from living organisms, embody the zenith of therapeutic progress driven by biotechnological breakthroughs. While oral drug delivery is convenient, it proves challenging for biopharmaceuticals due to the complex barriers in the gastrointestinal tract. Their delicate structure and susceptibility to degradation in the gut pose formidable obstacles. This scientific conundrum necessitates innovative solutions to ensure their effectiveness. Pseudomonas aeruginosa's Exotoxin A demonstrates the difficulty in traversing the intestinal epithelium, necessitating innovative strategies. Researchers utilize mucoadhesive, biodegradable polymers like alginate and chitosan to create nanoparticles. These nanoparticles form a protective gel in the stomach's acidic environment, enhancing drug stability and absorption. Chitosan and alginate collaborate in nanoparticle formulations, improving mucosal adhesion and prolonging drug retention. Introducing non-toxic Exotoxin A enhances trans-epithelial transport, validated by in vitro studies on Caco-2 cell monolayers and accumulation in the rat small intestine's lamina propria. Utilizing green fluorescent protein as a model within alginate-chitosan nanoparticles showcases their potential for oral drug delivery. Bacterial toxins play a crucial role in enhancing trans-epithelial transport, endorsing these nanoparticles. This fusion of biotechnology and polymer science offers a promising solution for biopharmaceutical oral delivery challenges, highlighting alginate-chitosan nanoparticles as versatile carriers for transformative drug delivery advancements.

A197 A ROLE FOR NOD2 IN INTESTINAL T CELL MEMORY DEVELOPMENT AND FUNCTION

Abstract Background Aberrant resident memory T cell (TRM) responses have been associated with increased intestinal inflammation and Crohn’s disease (CD) pathology in humans. Intestinal TRM cells are not only important for maintaining the integrity of the intestinal epithelial barrier, but also for the rapid clearance of pathogens in the intestine during infection. Understanding the signals received by the intestinal immune system to generate TRM responses is paramount to elucidating treatments for CD. Genetic mutations in NOD2 are associated with the highest risk of CD development. As a host intracellular sensor of bacterial peptidoglycan, NOD2 is critical for initiating both innate and adaptive immune responses. Furthermore, work from our lab as well as those of our collaborators suggest that NOD2 deficiency reduces systemic memory B and T cell responses. However, the role of NOD2 in establishing memory T cell responses in the intestine remains unclear. This work will therefore establish the role of NOD2 signaling in initiating and maintaining optimal TRM responses to achieve intestinal homeostasis and resilience to intestinal inflammation. Aims It is the main objective of this project to determine whether NOD2-mediated signalling affects: 1. Antigen-specific intestinal T cell priming in vivo 2. Bona fide intestinal TRM generation 3. Bona fide intestinal TRM function Methods Intraperitoneal LCMV-Armstrong infection results in long-lived CD4+ and CD8+ resident-memory T cell generation in the intestinal lamina propria of mice. Wildtype and NOD2 deficient littermate mice were infected with LCMV-Armstrong, and the effects on intestinal T cell priming, effector function, and memory T cell function were examined by flow-cytometry, ex vivo and in vivo antigen-recall experiments, qPCR, and viral plaque assays. Results Augmented NOD2 signalling during priming increased LCMV-specific CD4+ T cell numbers in the mesenteric lymph nodes - but not in the spleen, independent of proliferation or cell death. Furthermore, NOD2-deficiency resulted in decreased effector and memory T cell numbers in the small intestinal lamina propria. This effect was associated with decresead memory CD4+ and CD8+ T cell functions in NOD2-deficient mice during ex vivo and in vivo peptide recall experiments. Conclusions NOD2 affects T cell priming in the mesenteric lymph nodes, which later affects effector and memory T cell functions in the intestinal lamina propria. Funding Agencies CAG, CIHREmerging and Pandemic Infections Consortium

A43 MECHANISMS OF UNIQUE COLONIZATION DYNAMICS AND IMMUNE RESPONSES TO MURIBACULACEAE

Abstract Background Commercially available probiotics have a limited ability to alter the gut microbiome and establish within a pre-existing microbial community. Increases in osmolality, a condition prevalent in intestinal diseases, depletes the highly abundant bacterial family Muribaculaceae (Mb) from the gut microbiome in a mouse model of short-term osmotic laxative use. Excitingly, despite microbial community re-equilibration in its absence, Mb supersedes other bacterial colonizers to its original abundance if reintroduced, suggesting unique colonization attributes and a potential privileged immune interaction. Aims We aimed to investigate whether and how Mb colonization affects intestinal innate and adaptive immune homeostasis, including the generation of Mb-specific antibodies. Methods To examine interactions between Mb and the immune system that allows for efficient colonization, we used the osmotic laxative polyethylene glycol (PEG) to clear Mb and then generated mice with complex microbiomes that either lack Mb completely (Mb naïve) or were introduced to 8 murine-derived Mb strains (Mb+). The same strains were then introduced to Mb naïve mice (primary exposure to the immune system). To model secondary exposure, Mb+ mice were treated with PEG, and Mb re-introduced 3 weeks later. Leukocytes from the small and large intestinal lamina propria and gut-draining mesenteric lymph nodes (mLNs) were profiled over 21 days to characterize colonization and recolonization dynamics. Results High-throughput 16SrRNA sequencing showed no significant difference between relative abundance of Mb isolates during colonization or recolonization, indicating that Mb is capable of establishing in mice that have never been colonized with it before, making up to 20% of the relative abundance. Broad immunophenotyping demonstrated robust CD11b-CD103+ dendritic cell and Germinal Centre B cell responses in the mLNs of mice seeing Mb for the first time, yet no subsequent plasmablast accumulation in the mLN or lamina propria. We also observed significantly increased type two innate lymphoid cells in the small intestine upon primary exposure to Mb. Recolonization elicited no detectable changes in the monitored populations. Conclusions The lack of immune reactivity upon reintroduction to Mb suggests Mb may evade immune detection upon repeat exposure and contribute to its robust colonization abilities. Determining mechanisms involved in Mb colonization and its impact on host immune responses could increase our understanding of colonization dynamics and highlights the potential of Mb as a model for microbiota reintroduction in therapeutic applications. Funding Agencies Weston Family Foundation

Increased regulatory activity of intestinal innate lymphoid cells type 3 (ILC3) prevents experimental autoimmune encephalomyelitis severity

Experimental autoimmune encephalomyelitis (EAE) induced in inbred rodents, i.e., genetically identical animals kept under identical environmental conditions, shows variable clinical outcomes. We investigated such variations of EAE in Dark Agouti rats immunized with spinal cord homogenate and identified four groups: lethal, severe, moderate, and mild, at day 28 post immunization. Higher numbers of CD4+ T cells, helper T cells type 1 (Th1) and 17 (Th17) in particular, were detected in the spinal cord of the severe group in comparison with the moderate group. In addition, increased proportion of Th1 and Th17 cells, and heightened levels of interferon (IFN)-γ and interleukin (IL)-6 were detected in the small intestine lamina propria of the severe group. A selective agonist of free fatty acid receptor type 2 (Ffar2) applied orally in the inductive phase of EAE shifted the distribution of the disease outcomes towards milder forms. This effect was paralleled with potentiation of intestinal innate lymphoid cells type 3 (ILC3) regulatory properties, and diminished Th1 and Th17 cell response in the lymph nodes draining the site of immunization. Our results suggest that different clinical outcomes in DA rats are under determinative influence of intestinal ILC3 activity during the inductive phase of EAE.

Novel AHR ligand AGT-5 ameliorates type 1 diabetes in mice through regulatory cell activation in the early phase of the disease.

Type 1 diabetes (T1D) is an autoimmune disease with a strong chronic inflammatory component. One possible strategy for the treatment of T1D is to stimulate the regulatory arm of the immune response, i.e. to promote the function of tolerogenic dendritic cells (tolDC) and regulatory T cells (Treg). Since both cell types have been shown to be responsive to the aryl hydrocarbon receptor (AHR) activation, we used a recently characterized member of a new class of fluorescent AHR ligands, AGT-5, to modulate streptozotocin-induced T1D in C57BL/6 mice. Prophylactic oral administration of AGT-5 reduced hyperglycemia and insulitis in these mice. Phenotypic and functional analysis of cells in the pancreatic infiltrates of AGT-5-treated mice (at the early phase of T1D) revealed a predominantly anti-inflammatory environment, as evidenced by the upregulation of tolDC and Treg frequency, while CD8+ cell, Th1 and Th17 cells were significantly reduced. Similarly, AGT-5 enhanced the proportion of Treg and tolDC in small intestine lamina propria and suppressed the activation status of antigen-presenting cells through down-regulation of co-stimulatory molecules CD40, CD80 and CD86. The expression levels of Cyp1a1, controlled by the AHR, were increased in CD4+, CD8+ and Treg, confirming the AHR-mediated effect of AGT-5 in these cells. Finally, AGT-5 stimulated the function of regulatory cells in the pancreatic islets and lamina propria by upregulating indoleamine 2,3-dioxigenase 1 (IDO1) in tolDC. These findings were supported by the abrogation of AGT-5-mediated in vitro effects on DC in the presence of IDO1 inhibitor. AGT-5 also increased the expression of CD39 or CD73 ATP-degrading ectoenzymes by Treg. The increase in Treg is further supported by the upregulated frequency of IL-2-producing type 3 innate lymphoid cells (ILC3) in the lamina propria. Anti-inflammatory effects of AGT-5 were also validated on human tonsil cells, where in vitro exposure to AGT-5 increased the proportion of immunosuppressive dendritic cells and ILC3. These results suggest that AGT-5, by stimulating AHR, may promote a general immunosuppressive environment in the pancreas and small intestine lamina propria at the early phase of disease, and thereby inhibit the severity of T1D in mice.

Intestinal microbiota-specific Th17 cells possess regulatory properties and suppress effector T cells via c-MAF and IL-10

Commensal microbes induce cytokine-producing effector tissue-resident CD4+ Tcells, but the function of these Tcells in mucosal homeostasis is not well understood. Here, we report that commensal-specific intestinal Th17 cells possess an anti-inflammatory phenotype marked by expression of interleukin (IL)-10 and co-inhibitory receptors. The anti-inflammatory phenotype of gut-resident commensal-specific Th17 cells was driven by the transcription factor c-MAF. IL-10-producing commensal-specific Th17 cells were heterogeneous and derived from a TCF1+ gut-resident progenitor Th17 cell population. Th17 cells acquired IL-10 expression and anti-inflammatory phenotype in the small-intestinal lamina propria. IL-10 production by CD4+ Tcells and IL-10 signaling in intestinal macrophages drove IL-10 expression by commensal-specific Th17 cells. Intestinal commensal-specific Th17 cells possessed immunoregulatory functions and curbed effector Tcell activity invitro and invivo in an IL-10-dependent and c-MAF-dependent manner. Our results suggest that tissue-resident commensal-specific Th17 cells perform regulatory functions in mucosal homeostasis.

α-Glucosidase inhibitors boost gut immunity by inducing IgA responses in Peyer's patches.

Peyer's patches (PPs) are specialized gut-associated lymphoid tissues that initiate follicular helper T (Tfh)-mediated immunoglobulin A (IgA) response to luminal antigens derived from commensal symbionts, pathobionts, and dietary sources. IgA-producing B cells migrate from PPs to the small intestinal lamina propria and secrete IgA across the epithelium, modulating the ecological balance of the commensal microbiota and neutralizing pathogenic microorganisms. α-glucosidase inhibitors (α-GIs) are antidiabetic drugs that inhibit carbohydrate digestion in the small intestinal epithelium, leading to alterations in the commensal microbiota composition and metabolic activity. The commensal microbiota and IgA responses exhibit bidirectional interactions that modulate intestinal homeostasis and immunity. However, the effect of α-GIs on the intestinal IgA response remains unclear. We investigated whether α-GIs affect IgA responses by administering voglibose and acarbose to mice via drinking water. We analyzed Tfh cells, germinal center (GC) B cells, and IgA-producing B cells in PPs by flow cytometry. We also assessed pathogen-specific IgA responses. We discovered that voglibose and acarbose induced Tfh cells, GCB cells, and IgA-producing B cells in the PPs of the proximal small intestine in mice. This effect was attributed to the modification of the microbiota rather than a shortage of monosaccharides. Furthermore, voglibose enhanced secretory IgA (S-IgA) production against attenuated Salmonella Typhimurium. Our findings reveal a novel mechanism by which α-GIs augment antigen-specific IgA responses by stimulating Tfh-GCB responses in PPs, and suggest a potential therapeutic application as an adjuvant for augmenting mucosal vaccines.

Cellular evidence of communication strategies for small intestinal high endothelial cells: Ultrastructural insights of nano-scale exosomes and autophagy

Although several immune related cells of small intestine play an essential role in the intestinal homeostasis. However, information related to ultrastructural evidence of Nano-scale exosomes-multivesicular bodies and autophagic pathway in the high endothelial cells (HECs) of the small intestine in laying birds is still ambiguous. In present study, the HECs secreted the early endosome (ee), late endosome (le) and multivesicular bodies (MVBs) in the lamina propria of layer small intestine was confirmed by transmission electron microscopy. Besides that, in the cytoplasm of HECs showed many autophagosomes were directly associated with lysosomes and mitochondria. Further, the immunohistochemistry and immunofluorescence results showed that, the immunoreactivity and immuno-signaling of Nano-scale exosome related proteins, cluster of differentiation (CD63) and tumor susceptibility gene (TSG101), and autophagic related proteins, autophagic related gene (ATG7) and microtubule-associated protein light chain (LC3) were strong positive expression in the lamina propria of small intestine. These results prove that HECs play a well-known immunological role in the maintenance of intestinal homeostasis. In summary, these findings indicate that the small intestine’s HECs have developed an innovative way of communication.

Maternal polysorbate 80 exposure causes intestinal ILCs and CD4+ T cell developmental abnormalities in mouse offspring

This study aimed to investigate the transgenerational impacts of maternal intake of polysorbate 80 (P80), an emulsifier widely used in modern society, on the development of offspring immunity. Our results revealed that maternal P80 treatment led to impaired differentiation of innate lymphoid cells (ILCs) and CD4+ T cells in the small intestinal lamina propria (SiLP), resulting in intestinal dyshomeostasis in female offspring. Furthermore, we found that SiLP ILCs abundances were significantly altered in 0-day-old fetuses from P80-treated mothers, indicating a prenatal impact of P80-treated mothers on offspring immunity. Additionally, cesarean section and foster-nursing studies demonstrated that P80-induced altered SiLP ILCs in 0-day-old fetuses could further induce dysregulation of ILCs and CD4+ T cells in the SiLP, thus promoting intestinal dysregulation in offspring later in life. Overall, our findings suggest that maternal P80 intake could prenatally program the development of offspring immunity, exerting a significant and long-lasting impact.

Visualizing the activation of encephalitogenic T cells in the ileal lamina propria by in vivo two-photon imaging

Autoreactive encephalitogenic T cells exist in the healthy immune repertoire but need a trigger to induce CNS inflammation. The underlying mechanisms remain elusive, whereby microbiota were shown to be involved in the manifestation of CNS autoimmunity. Here, we used intravital imaging to explore how microbiota affect the T cells as trigger of CNS inflammation. Encephalitogenic CD4+ T cells transduced with the calcium-sensing protein Twitch-2B showed calcium signaling with higher frequency than polyclonal T cells in the small intestinal lamina propria (LP) but not in Peyer's patches. Interestingly, nonencephalitogenic T cells specific for OVA and LCMV also showed calcium signaling in the LP, indicating a general stimulating effect of microbiota. The observed calcium signaling was microbiota and MHC class II dependent as it was significantly reduced in germfree animals and after administration of anti-MHC class II antibody, respectively. As a consequence of T cell stimulation in the small intestine, the encephalitogenic T cells start expressing Th17-axis genes. Finally, we show the migration of CD4+ T cells from the small intestine into the CNS. In summary, our direct in vivo visualization revealed that microbiota induced T cell activation in the LP, which directed T cells to adopt a Th17-like phenotype as a trigger of CNS inflammation.

Coexistence of apoptosis, pyroptosis, and necroptosis pathways in celiac disease.

Usually, the massive elimination of cells under steady-state conditions occurs by apoptosis, which is also acknowledged to explain the loss of enterocytes in the small intestine of celiac disease (CD) patients. However, little is known about the role of proinflammatory cell death pathways in CD. Here, we have used confocal microscopy, western blot, and RT-qPCR analysis to assess the presence of regulated cell death pathways in the duodenum of CD patients. We found an increased number of dead (TUNEL+) cells in the lamina propria of small intestine of CD patients, most of them are plasma cells (CD138+). Many dying cells expressed FAS and were in close contact with CD3+ T cells. Caspase-8 and caspase-3 expression was increased in CD, confirming the activation of apoptosis. In parallel, caspase-1, IL-1β, and GSDMD were increased in CD samples indicating the presence of inflammasome-dependent pyroptosis. Necroptosis was also present, as shown by the increase of RIPK3 and phosphorylate MLKL. Analysis of published databases confirmed that CD has an increased expression of regulated cell death -related genes. Together, these results reveal that CD is characterized by cell death of different kinds. In particular, the presence of proinflammatory cell death pathways may contribute to mucosal damage.