The role of the intestinal context in the generation of tolerance and inflammation

Nutritional status and prognosis in children with immunodeficiencies undergoing hematopoietic stem cell transplantation

BACKGROUND

Primary immunodeficiencies (PID) are diseases resulting from genetic dysfunctions in the immune system, which can result in recurrent infections, autoimmunity and even malignancy. It is estimated that approximately one-third of the PID described have gastrointestinal components or symptoms involved and may present an increased risk of weight loss and failure to thrive. It is also known that, in patients with other diagnoses, malnutrition may be associated with worse outcomes after hematopoietic stem cell transplantation (HSCT).

OBJECTIVE

to characterize the nutritional status of pediatric patients with PID at the time of admission for HSCT and to establish the relationship between baseline nutritional status measures and post-HSCT clinical outcomes.

METHODS

a retrospective analytical observational study, based on data from pediatric patients, of both sexes and all ethnicities, with PID, submitted to HSCT in the period from 2004 to 2019. The risk factors analyzed were the Z-scores of weights for age (W/A), height for age (H/A), BMI for age (BMI/A) and Sum score, obtained by through the sum of the W/A and H/A scores. The primary outcomes were overall survival at 6 months, occurrence of acute Graft Versus Host Disease (aGVHD) at 6 months, and occurrence of chronic Graft Versus Host Disease (cGVHD) at 1 year. Secondary outcomes were occurrence and degree of mucositis, length of stay, and total number of infectious episodes. As statistical analysis, the ANOVA model, the Tukey test, ROC curves and Kaplan Meier and Log-Rank analysis were used. Multivariate survival and logistic regression models were also performed.

RESULTS

The study showed important indicators of malnutrition in patients with PID, especially those diagnosed with Severe Combined Immunodeficiency Syndrome (SCID) and Hemophagocytic Syndromes (HS). Among those with SCID, 60% had low or very low weight for their age, 52% had low or very short stature for their age, and 44% were classified as being thin or very thin. Among patients with HS, 75% had short or very short stature for their age. Multivariate analysis only demonstrated association between W/A score with extensive cGVHD, controlling for diagnosis, compatibility, conditioning and immunoprophylaxis. Lower W/A values were associated with higher occurrences of these events. Although W/A was only associated with cGVHD and H/A had no association with chronic or acute GVHD, when Sum scores were used, the lower values the higher rates of severe aGVHD and total cGVHD according to multivariate controlled models for diagnosis, compatibility, conditioning and immunoprophylaxis.

CONCLUSIONS

Our study characterized the nutritional status of children with PID undergoing HSCT and found alarming rates of underweight and short stature in patients with SCID and HS. We also demonstrated a relationship between anthropometric parameters and outcomes such as mortality, the occurrence of GVHD and severe mucositis after HSCT. In this sense, W/A and Sum score measures would be good prognostic methods for these outcomes. Henceforth, prospective studies are needed to confirm these findings and establish new nutritional assessment criteria for this population.

Needs for Increased Awareness of Gastrointestinal Manifestations in Patients With Human Inborn Errors of Immunity

The gastrointestinal (GI) tract is frequently affected by inborn errors of immunity (IEI), and GI manifestations can be present in IEI patients before a diagnosis is confirmed. We aimed to investigate clinical features, endoscopic and histopathologic findings in IEI patients. This was a retrospective cohort study conducted from 1995 to 2020. Eligible patients were diagnosed with IEI and had GI manifestations that were enough to require endoscopies. IEI was classified according to the International Union of Immunological Societies classification. Of 165 patients with IEI, 55 (33.3%) had GI manifestations, and 19 (11.5%) underwent endoscopy. Among those 19 patients, nine (47.4%) initially presented with GI manifestations. Thirteen patients (68.4%) were male, and the mean age of patients 11.5 ± 7.9 years (range, 0.6 – 26.6) when they were consulted and evaluated with endoscopy. The most common type of IEI with severe GI symptoms was “Disease of immune dysregulation” (31.6%) followed by “Phagocyte defects” (26.3%), according to the International Union of Immunological Societies classification criteria. Patients had variable GI symptoms such as chronic diarrhea (68.4%), hematochezia (36.8%), abdominal pain (31.6%), perianal disease (10.5%), and recurrent oral ulcers (10.5%). During the follow-up period, three patients developed GI tract neoplasms (early gastric carcinoma, mucosa associated lymphoid tissue lymphoma of colon, and colonic tubular adenoma, 15.8%), and 12 patients (63.2%) were diagnosed with inflammatory bowel disease (IBD)-like colitis. Investigating immunodeficiency in patients with atypical GI symptoms can provide an opportunity for correct diagnosis and appropriate disease-specific therapy. Gastroenterologists and immunologists should consider endoscopy when atypical GI manifestations appear in IEI patients to determine if IBD-like colitis or neoplasms including premalignant and malignant lesions have developed. Also, if physicians in various fields are better educated about IEI-specific complications, early diagnosis and disease-specific treatment for IEI will be made possible.

Primary Immunodeficiency and the Gut

This article presents the most common gastrointestinal, hepatic, and pancreatic manifestations of the primary immunodeficiency diseases, including the appropriate laboratory testing, endoscopic evaluation, and recommendations for further management.

Mysterious effects of olfactory pathway lesions on intestinal immunodeficiency targeting Peyer's patches: The first experimental study

BACKGROUND

Although olfaction has been considered as important neuroimmunomodulatory foundation, there is no satisfying analytical information between neurohistomorphological features olfactory networks and intestinal immune system hardwares. We studied if the olfactory bulb lesions (OBL) may rely on histopathological features of intestinal lymphatic Peyer's patches in an animal model.

METHODS

Thirty-two rats were grouped as control (Group I, n = 8), SHAM (Group II, n = 7) and OBL (Group III, n = 17) respectively; and followed eight weeks and animals were decapitated. The olfactory bulbs and intestines were extracted. Specimens stained with hematoxylin/eosin and GFAP methods and analyzed Stereologically to evaluate volume loss of olfactory bulbs and Peyer's patches volumes (PV) of intestines per cubic millimeter and compared with each other's statistically.

RESULTS

The mean olfactory bulbs volumes were estimated as 3.65 ± 0.32/mm³ in group I, 3.12 ± 0.20/mm³ in group II and 2.21 ± 0.15/mm³ in group III (p < 0.0005 Group III vs. I and II). The mean of PV were estimated as; (9 ± 2) × 10⁶ µm³/cm³ in Group-I, (12 ± 3) × 10⁶ µm³/cm³ in Group-II; and (23 ± 4) × 10⁶ µm³/cm³ in group-III (p < 0.005 Group II vs. I, p < 0.0005 Group III vs. I-II).

CONCLUSIONS

OBL could rely on intestinal immunodeficiency causing by olfaction loss induced denervation injury of Peyer's patches.

Inflammatory Bowel Disease at the Intersection of Autophagy and Immunity: Insights from Human Genetics

Studies using human genetics have identified more than 160 loci that affect the risk of developing inflammatory bowel disease (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC). Several of these genes have been found to play key roles in the process of autophagy, a lysosome-based degradation pathway. Although historically considered to be a relatively nonselective process of degradation of cytosolic contents, autophagy has recently been revealed to have several selective and immune-specific functions that are relevant to the maintenance of intestinal homeostasis, including xenophagy, mitophagy, antigen presentation, secretion, and inflammasome regulation. In this chapter, we review the evidence that links autophagy-related genes, their immune-specific functions, and possible mechanisms of IBD pathogenesis. We summarize the basic molecular events underlying general and selective autophagy, and present evidence suggesting possible pathogenic mechanisms revealed by studies of IBD-associated risk alleles of ATG16L1 and IRGM. Finally, we review chemical biology-based experimental approaches for identifying autophagy regulatory pathways that may have implications for the development of therapeutics.

Participation of Leukotrienes in the Immune Modulation of Oral Tolerance

Oral tolerance (OT) is characterized as a peripheral immune tolerance form, in which, mature lymphocytes in lymphoid tissues associated with mucosa, become non-functional or hypo responsive due to prior oral administration of antigen. OT is an important immunological phenomenon due to its therapeutic potential in inflammatory processes and others diseases. Here we evaluated leukotriene role in the induction of OT, as well as, the production of cytokines IL-5 and IFN-γ in leukotriene deficient animals (knock-out). Our results suggested that even in the presence of OT and leukotrienes absence, cytokine IFN-γ remains being secreted, which gives us an indication of immune system specificity and also that IFN-γ participates in various immune processes.

Utilising a simulation platform to understand the effect of domain model assumptions

Computational and mathematical modelling approaches are increasingly being adopted in attempts to further our understanding of complex biological systems. This approach can be subjected to strong criticism as substantial aspects of the biological system being captured are not currently known, meaning assumptions need to be made that could have a critical impact on simulation response. We have utilised the CoSMoS process in the development of an agent-based simulation of the formation of Peyer's patches (PP), gut-associated lymphoid organs that have a key role in the initiation of adaptive immune responses to infection. Although the use of genetic tools, imaging technologies and ex vivo culture systems has provided significant insight into the cellular components and associated pathways involved in PP development, interesting questions remain that cannot be addressed using these approaches, and as such well justified assumptions have been introduced into our model to counter this. Here we focus not on the development of the model itself, but instead demonstrate how the resultant simulation can be used to assess how these assumptions impact the simulation response. For example, we consider the impact of our assumption that the migration rate of lymphoid tissue cells into the gut remains constant throughout PP development. We demonstrate that an analysis of the assumptions made in the construction of the domain model may either increase confidence in the model as a representation of the biological system it captures, or may suggest areas where further biological experimentation is required.

Dysbiotic events in gut microbiota: impact on human health

The human body is colonized by a large number of microbes coexisting peacefully with their host. The most colonized site is the gastrointestinal tract (GIT). More than 70% of all the microbes in the human body are in the colon. The microorganism population is 10 times larger of the total number of our somatic and germ cells. Two bacterial phyla, accounting for more than 90% of the bacterial cells, dominate the healthy adult intestine: Firmicutes and Bacteroidetes. Considerable variability in the microbiota compositions between people is found when we look at the taxonomic level of species, and strains within species. It is possible to assert that the human microbiota could be compared to a fingerprint. The microbiota acts as a barrier from pathogens, exerts important metabolic functions, and regulates inflammatory response by stimulating the immune system. Gut microbial imbalance (dysbiosis), has been linked to important human diseases such as inflammation related disorders. The present review summarizes our knowledge on the gut microbiota in a healthy context, and examines intestinal dysbiosis in inflammatory bowel disease (IBD) patients; the most frequently reported disease proven to be associated with changes in the gut microbiota.

Proliferation and apoptosis of Peyer's patches and its lymphocytes in experimental terminal ileitis

This study will provide guide for the terminal ileitis in clinical diagnosis and treatment. The animals were been done terminal ileum-cecum side to side anastomosis, terminal ileum operation line and only anesthesia treatment, respectively. The model group presented acute inflammation after surgery for 2 weeks and the inflammation was limited to the mucosal layer. Animals presented chronic inflammation to 8 weeks, mucosal membrane was given priority to with lymphocytic infiltrates. In 2 weeks and 4 weeks, the number of Peyer's patches (PP knot) and PP knot lymphocytes increased significantly in the model group (P < 0.05, P < 0.01). At 8 weeks, the suture group and the model group presented a large number of lymphocytic apoptosis (P < 0.01). Rat ileal PP knot lymphocyte small molecule DNA showed typical "trapezoid" bands. We observed apparent morphology of apoptosis and crescent-shaped nucleus. Continuous immune response in terminal ileitis plays a considerable role in the process of the disease.

The role of Helicobacter pylori infection in the development of allergic asthma

Asthma is one of the most prevalent chronic diseases in developed countries, with steady increases in asthma prevalence evident, particularly in the last few decades. As genetic factors are unlikely to contribute to the rise in asthma prevalence, changes in lifestyle and exposure to environmental stimuli have been proposed to account for this trend. The 'disappearing microbiota' hypothesis postulates that major shifts in the human microbiome, resulting from dramatic lifestyle changes, account for the increase in asthma prevalence. In this context, persistent gastric colonization with the human-specific pathogen Helicobacter pylori has been negatively associated with the occurrence of asthma in epidemiological studies. In addition, experimental models of allergic airway disease revealed a direct link between infection with H. pylori and suppression of allergic airway disease through the induction of regulatory T cells. These and other new insights hold the promise of opening up new avenues toward the development of innovative, new strategies directed at asthma treatment and prevention.

Inflammatory Bowel Disease at the Intersection of Autophagy and Immunity: Insights from Human Genetics

Studies using human genetics have identified more than 160 loci that affect the risk of developing inflammatory bowel disease (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC). Several of these genes have been found to play key roles in the process of autophagy, a lysosome-based degradation pathway. Although historically considered to be a relatively nonselective process of degradation of cytosolic contents, autophagy has recently been revealed to have several selective and immune-specific functions that are relevant to the maintenance of intestinal homeostasis, including xenophagy, mitophagy, antigen presentation, secretion, and inflammasome regulation. In this chapter, we review the evidence that links autophagy-related genes, their immune-specific functions, and possible mechanisms of IBD pathogenesis. We summarize the basic molecular events underlying general and selective autophagy and present evidence suggesting possible pathogenic mechanisms revealed by studies of IBD-associated risk alleles of ATG16L1 and IRGM. Finally, we review chemical biology-based experimental approaches for identifying autophagy regulatory pathways that may have implications for the development of therapeutics.

Common alleles that influence autophagy and the risk for inflammatory bowel disease

Genetic studies of inflammatory bowel disease (IBD) have identified multiple risk loci that contain genes involved in autophagy. Although autophagy was traditionally considered to be a homeostatic response to ensure the recycling of cellular materials, it has now been additionally established to have roles in immunity and inflammation. In this review, we highlight how genetics have begun to identify a broader role for autophagy as a key pathway in Crohn's disease (CD). We review recent studies that have implicated autophagy in the regulation of mucosal homeostasis, including roles in intracellular defense, vesicular trafficking, and inflammatory signaling. Finally, we discuss studies that have begun to demonstrate how CD risk polymorphisms cause defects in autophagy and promote a breakdown of intestinal homeostasis.

The effects of TLR activation on T-cell development and differentiation

Invading pathogens have unique molecular signatures that are recognized by Toll-like receptors (TLRs) resulting in either activation of antigen-presenting cells (APCs) and/or costimulation of T cells inducing both innate and adaptive immunity. TLRs are also involved in T-cell development and can reprogram Treg cells to become helper cells. T cells consist of various subsets, that is, Th1, Th2, Th17, T follicular helper (Tfh), cytotoxic T lymphocytes (CTLs), regulatory T cells (Treg) and these originate from thymic progenitor thymocytes. T-cell receptor (TCR) activation in distinct T-cell subsets with different TLRs results in differing outcomes, for example, activation of TLR4 expressed in T cells promotes suppressive function of regulatory T cells (Treg), while activation of TLR6 expressed in T cells abrogates Treg function. The current state of knowledge of regarding TLR-mediated T-cell development and differentiation is reviewed.