Altered Immune Homeostasis Research Articles

Investigations on the Ability of the Insular Cortex to Process Peripheral Immunosuppression

The brain and immune system communicate through complex bidirectional pathways, but the specificity by which the brain perceives or even remembers alterations in immune homeostasis is still poorly understood. Recent data revealed that immune-related information under peripheral inflammatory conditions, termed as “immunengram”, were represented in specific neuronal ensembles in the insular cortex (IC). Chemogenetic reactivation of these neuronal ensembles was sufficient to retrieve the inflammatory stages, indicating that the brain can store and retrieve specific immune responses. Against this background, the current approach was designed to investigate the ability of the IC to process states of immunosuppression pharmacologically induced by the mechanistic target of rapamycin (mTOR) inhibitor rapamycin. We here show that the IC perceives the initial state of immunosuppression, reflected by increased deep-brain electroencephalography (EEG) activity during acute immunosuppressive drug treatment. Following an experienced period of immunosuppression, though, diminished splenic cytokine production as formerly induced by rapamycin could not be reinstated by nonspecific chemogenetic activation or inhibition of the IC. These findings suggest that the information of a past, or experienced status of pharmacologically induced immunosuppression is not represented in the IC. Together, the present work extends the view of immune-to-brain communication during the states of peripheral immunosuppression and foster the prominent role of the IC for interoception.

Lupus progression deteriorates oogenesis quality in MRL/lpr mice.

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the activation of the immune response against self antigens. Numerous reproductive complications, including reduced birth rate and complications for the mother and the fetus during pregnancy, have been observed in women with SLE. In the present study, we aimed to investigate the effect of SLE development on oocyte meiosis in lupus-prone mice. Lupus-prone MRL/lpr mice were used for the experiments: disease-free (4weeks of age) and sick (20weeks of age, virgin and postpartum). The immune response was monitored by flow cytometry, ELISpot, ELISA, and histology. Oocytes were analyzed by fluorescence microscopy based on chromatin, tubulin, and actin structures. The lupus-prone MRL/lpr mice developed age-dependent symptoms of SLE with increased levels of various autoantibodies, proteinuria, and renal infiltrates and a tendency for the immune response to worsen with changes in cell populations and the cytokine profile. The number and quality of oocytes were also affected, and the successful pregnancy rate of MRL/lpr mice was limited to only 60%. Isolated oocytes showed severe structural changes in all studied groups. Systemic alterations in immune homeostasis in SLE affect the quality of developing oocytes, which is evident from a young age. The data obtained is in line with the trend of reduced fertility in lupus-prone MRL/lpr mice. The phenomenon can be explained by changes in the microenvironment of the relevant organs and close connection between ovulation and inflammatory processes.

Immune dysregulation in children with inherited bone marrow failure syndromes and refractory cytopenia of childhood

Background and AimsInherited bone marrow failure syndromes (IBMFS) are usually identified when patients develop hematologic complications, such as severe BMF, myelodysplastic syndrome or leukemia. In clinical practice, differential diagnosis with refractory cytopenia of childhood (RCC) or autoimmune cytopenia with or without an underlying Inborn Error of Immunity (IEI) may be challenging. To fill this gap, we aim at profiling the immunological landscape associated with pediatric chronic cytopenia(s). MethodsWe enrolled patients presenting with chronic cytopenia (>12 months): isolated autoimmune cytopenia(s) (AIC, N = 11); IBMFS (N = 12: 4 Diamond-Blackfan; 4 Shwackman-Diamond, 2 Fanconi anemia, 1 RTEL1-Dyskeratosis congenita, 1 RUNX1-deficiency) and RCC (N = 6). Extended immunophenotyping from peripheral blood was performed to compare the AIC to IBMFS and RCC group.Table 1(abstract: 86) Clinical features of IBMFS and RCC patient cohorts. A, anemia; L, leukopenia; N, neutropenia; T, thrombocytopenia; PAN, pancytopenia; (*) siblings.DIAGNOSISMUTATED GENECYTOPENIA LINEAGEADDITIONAL CLINICAL FEATURESAGE AT FLOW ANALYSIS (y)IBMFSDiamond-Blackfan anemia (N=4)RPS19APancreas annularis11ongoingA + L/0,5N.A.AGH deficiency, suppurative sialadenitis, interatrial defect16N.A.AAtrial septal defect21Shwachman Diamond syndrome (N=4)SBDSA + NGH deficiency, pancreatic insufficiency, bone abnormalities, nephrocalcinosis12SBDSNGrowth retardation, pancreatic insufficiency, hepatitis (unknown cause), bone abnormalities, osteopenia15SBDSNGrowth retardation, intestinal malrotation, cleft palate16N.A.NGrowth retardation, pancreatic insufficiency, bone abnormalities18Fanconi anemia (N=2*)BRIP1 (FANCJ)A + T/16BRIP1 (FANCJ)/Precocious puberty, congenital melanocytic nevus9RUNX1 deficiencyRUNX1N + T/15Dyskeratosis congenitaRTEL1PANUpper esophageal stricture19RCCHebo deficiencyERCC6L2N + T/13Refractory cytopenia (N=5)/A + T/16/N + T/14N.A.PAN/9NonePANSeronegative autoimmune hepatitis, eczema, hydronephrosis4NonePANSeronegative autoimmune hepatitis11 Results:Lymphocyte subpopulations analysis revealed lower frequencies of CD4 Recent Thymic Emigrants (RTEs) in the IBMFS group (p = 0.020), CD4 naïve T cells in both IBMFS (p = 0.002) and RCC (p = 0.041) patients and CD8 naïve T cells in IBMFS group (p = 0.021), counterbalanced by a higher frequency of CD4 central memory (CM; p = 0.001 for IBMFS; p = 0.022 for RCC) and CD8 CM T cells (p < 0.05 for IBMFS and RCC). A similar profile was detected in both cohorts for naïve Tregs (p < 0.05) towards memory Tregs (p <0.05). ConclusionsWe observed a striking T cell immunedysregulation due to an imbalance towards the memory compartment in pediatric patients with RCC and IBMFS. As this scenario is reminiscent of what observed in patients with AIC associated with signs of IEI, further investigations are required to define the pathogenicity of the altered immune homeostasis. Nevertheless, peripheral immunophenotyping confirms to be a useful screening tool able to facilitate differential diagnosis in pediatric cytopenia. [Display omitted]

NAFLD and HBV interplay - related mechanisms underlying liver disease progression.

Non-alcoholic fatty liver disease (NAFLD) and Hepatitis B virus infection (HBV) constitute common chronic liver diseases with worldwide distribution. NAFLD burden is expected to grow in the coming decade, especially in western countries, considering the increased incidence of diabetes and obesity. Despite the organized HBV vaccinations and use of anti-viral therapies globally, HBV infection remains endemic and challenging public health issue. As both NAFLD and HBV have been associated with the development of progressive fibrosis, cirrhosis and hepatocellular carcinoma (HCC), the co-occurrence of both diseases has gained great research and clinical interest. The causative relationship between NAFLD and HBV infection has not been elucidated so far. Dysregulated fatty acid metabolism and lipotoxicity in NAFLD disease seems to initiate activation of signaling pathways that enhance pro-inflammatory responses and disrupt hepatocyte cell homeostasis, promoting progression of NAFLD disease to NASH, fibrosis and HCC and can affect HBV replication and immune encountering of HBV virus, which may further have impact on liver disease progression. Chronic HBV infection is suggested to have an influence on metabolic changes, which could lead to NAFLD development and the HBV-induced inflammatory responses and molecular pathways may constitute an aggravating factor in hepatic steatosis development. The observed altered immune homeostasis in both HBV infection and NAFLD could be associated with progression to HCC development. Elucidation of the possible mechanisms beyond HBV chronic infection and NAFLD diseases, which could lead to advanced liver disease or increase the risk for severe complications, in the case of HBV-NAFLD co-existence is of high clinical significance in the context of designing effective therapeutic targets.

Influence of Micronutrients in The Alleviation of Immunotoxicity Induced by Poly Aromatic Hydrocarbons Naphthalene and Anthracene

Diet plays a major role in fine tuning the immune system and to combat against dreadful diseases and infections. Micronutrients form an important part of balanced diet and enable efficient functioning of the immune system. Vitamins, minerals and trace elements comprise the major category of micronutrients. Deficiency of micronutrients could culminate in suppression of both adaptive and innate immunity leading to altered immune homeostasis. Anthracene and naphthalene are two environmental pollutants which are highly toxic, carcinogenic poly cyclic aromatic hydrocarbons that gains entry in to the human system through multiple modes. The aim of the current study is to evaluate the potential of four dietary micronutrients Vitamin A, Vitamin C, Folic acid and Zinc to counteract the immunotoxic effects of naphthalene and anthracene on Murine macrophage cell line RAW 264.7. Several cell based assays like MTT assay, LDH leakage assay, Crystal violet test, DCFDA analysis (for ROS generation) and Rhodamine B assay (for measurement of mitochondrial membrane potential) were taken as end point indicators to support the findings of the study. The results showed that, both naphthalene and anthracene triggered the production of ROS, altered mitochondrial membrane potential, and induced strong immunosuppressive effects. The immunosuppressive effect was found to be more prevalent in anthracene treated cells. Pre-treatment with the micronutrients exhibited considerable protection against naphthalene and anthracene induced changes in the cells primarily through the antioxidant and immunomodulatory effects. The overall protective effects offered against naphthalene and anthracene was found to be superior in the Vitamin A treated cells as compared Vitamin C, Folic acid and Zinc treated cells. Prolonged immunosuppression reduces immune surveillance and hence could activate oncogenic signals leading to carcinogenic conditions. Regular micronutrient supplementation in the diet could help considerably to negate or prevent these deleterious conditions.

Transcriptome analysis and identification of age-associated fertility decreased genes in hen uterovaginal junction

Avian sperm storage tubules (SSTs), which are located in the uterovaginal junction (UVJ) of the oviduct, are primary sperm storage sites after mating or artificial insemination. The mechanism underlying reduced sperm storage efficiency of SSTs which is highly correlated with decreased fertility rates in aged laying breeders remains largely unclear. Here, comparative transcriptomic analysis between the aged and young White Leghorn hens (120 vs. 30 wk) was applied to identify gene expression changes of UVJs containing SSTs. Bioinformatics analysis revealed 567 upregulated and 1998 downregulated differentially expressed genes. Gene ontology analysis was highly enriched in terms of immune system, cell adhesion, and cytoskeleton proteins. Kyoto Encyclopedia of Genes and Genomes analysis revealed 5 significant (P < 0.05) pathways including inositol phosphate and glycerophospholipid metabolism. β-Galactosidase staining of chicken UVJ sections suggested increased cell senescence via aging. Oil Red O staining and immunohistochemistry detection of ADFP both confirmed distribution of lipid droplets in SST cells with increased intensity in aged breeders. The lipid synthesis and metabolism-related genes represented by TFAP2 and PLD1 were differentially expressed in aged laying breeders. The upregulation of IL15 and downregulation of a large number of immune-related genes in aged breeders indicate altered immune homeostasis in UVJs and SSTs. The increased accumulation of lipids, and altered immunity homeostasis, combined with other factors (TJP1, MYL9, AFDN, and RPL13, etc.) are potentially dominant effectors to decrease the sperm storage efficiency and egg fertility in aged laying breeders.

Sepsis and Cancer: An Interplay of Friends and Foes.

Sepsis and cancer share a number of pathophysiological features, and both result from the inability of the host's immune system to cope with the initial insult (tissue invasion by pathogens and malignant cell transformation, respectively). The common coexistence of both disorders and the profound related alterations in immune homeostasis raise the question of their mutual impact on each other's course. This translational review aims to discuss the interactions between cancer and sepsis supported by clinical data and the translation to experimental models. The dramatic improvement in cancer has come at a cost of increased risks of life-threatening infectious complications. Investigating the long-term outcomes of sepsis survivors has revealed an unexpected susceptibility to cancer long after discharge from the ICU. Nonetheless, it is noteworthy that an acute septic episode may harbor antitumoral properties under particular circumstances. Relevant double-hit animal models have provided clues to whether and how bacterial sepsis may impact malignant tumor growth. In sequential sepsis-then-cancer models, postseptic mice exhibited accelerated tumor growth. When using reverse cancer-then-sepsis models, bacterial sepsis applied to mice with cancer conversely resulted in inhibition or even regression of tumor growth. Experimental models thus highlight dual effects of sepsis on tumor growth, mostly depending on the sequence of insults, and allow deciphering the immune mechanisms and their relation with microorganisms.

The gut microbiome in psoriasis and psoriatic arthritis.

This review summarizes existing research on the gut microbiome composition and function in psoriasis and psoriatic arthritis, exploring potential roles in disease pathogenesis, progression, and management. A strong relationship between skin, joint, and gastrointestinal inflammation exists, as demonstrated by an increased prevalence of psoriasis, psoriatic arthritis, and inflammatory bowel disease co-occurring together; however, the link between them has not been fully elucidated. Studies analyzing the gut microbiome in psoriasis and psoriatic arthritis reveal a unique pattern of dysbiosis. With regard to the gut microbiome's role in psoriasis and psoriatic arthritis pathogenesis, we discuss several theories including intestinal permeability, altered immune homeostasis, and imbalance of short- and medium-chain fatty acid-producing bacteria. We also discuss how the gut microbiome affects patient risk of psoriatic arthritis and other serious comorbidities, and how fecal microbes could be used clinically as therapeutic targets or markers of disease.

Malt1 Protease Deficiency in Mice Disrupts Immune Homeostasis at Environmental Barriers and Drives Systemic T Cell-Mediated Autoimmunity.

The paracaspase Malt1 is a key regulator of canonical NF-κB activation downstream of multiple receptors in both immune and nonimmune cells. Genetic disruption of Malt1 protease function in mice and MALT1 mutations in humans results in reduced regulatory T cells and a progressive multiorgan inflammatory pathology. In this study, we evaluated the altered immune homeostasis and autoimmune disease in Malt1 protease-deficient (Malt1PD) mice and the Ags driving disease manifestations. Our data indicate that B cell activation and IgG1/IgE production is triggered by microbial and dietary Ags preferentially in lymphoid organs draining mucosal barriers, likely as a result of dysregulated mucosal immune homeostasis. Conversely, the disease was driven by a polyclonal T cell population directed against self-antigens. Characterization of the Malt1PD T cell compartment revealed expansion of T effector memory cells and concomitant loss of a CD4+ T cell population that phenotypically resembles anergic T cells. Therefore, we propose that the compromised regulatory T cell compartment in Malt1PD animals prevents the efficient maintenance of anergy and supports the progressive expansion of pathogenic, IFN-γ-producing T cells. Overall, our data revealed a crucial role of the Malt1 protease for the maintenance of intestinal and systemic immune homeostasis, which might provide insights into the mechanisms underlying IPEX-related diseases associated with mutations in MALT1.

2269 An Unprovoked Crisis: Hemophagocytic Lymphohistiocytosis

INTRODUCTION: Hemophagocytic Lymphohistiocytosis (HLH) is a syndrome of dysregulated immune response due to abnormal immune activation which can be life threatening and very aggressive. Here we report a woman with jaundice found to have hemophagocytosis on a bone marrow aspirate. CASE DESCRIPTION/METHODS: A 48-year-old woman with no past medical history presented with a diffuse erythematous morbilliform rash, fever, chills, and headache for one week. The headache is described as throbbing with associated photophobia. There was no history of travel, or hiking. On physical exam, the patient was afebrile but tachycardic, her BP was 85/64 mmHg, she was ill appearing, lethargic, and had scleral icterus. Her abdomen was tender to palpation with hepatosplenomegaly. She had a diffuse maculopapular rash. Labs were notable for hypoproliferative anemia, bandemia of 36%, thrombocytopenia, elevated AST/ALT, total bilirubin with predominance of direct bilirubin, alkaline phosphatase, and lactate. CT abdomen revealed moderate diffuse colonic wall thickening from the cecum to rectum. In the meantime, a very extensive infectious workup was sent. A bone marrow biopsy revealed a mildly hypercellular marrow with hemophagocytosis. Soluble CD-25 was found to be significantly elevated. The patient’s mental status continued to deteriorate and had to be transferred to MICU for airway protection. She received steroids, etoposide, and was eventually started on emapalumab due to progression in symptoms. The patient significantly improved, and was extubated. Over two weeks her mental status returned back to baseline. DISCUSSION: HLH results from the inability to downregulate active macrophages and lymphocytes. The primary tissue damage mechanism is thought to be due to cytokine release secondary to immune activation. The instigating factor for HLH is typically an infection or an altered immune homeostasis state. The typical presentation of HLH involves fevers, bicytopenia, splenomegaly, hemophagocytosis, elevated soluble CD25, hypertriglyceridema, hepatitis, and elevated ferritin. The dilemma in the case we present remains in the trigger for HLH; the extensive infectious workup was completely unrevealing, with the patient being negative to some of the very common viral pathogens. There is no family history of HLH or any immune related disorders, and she had no past medical history. With that being said, an episode of HLH of unknown etiology seems to have been the cause of her symptoms.

Mass-cytometry reveals global immune remodeling with multi-lineage hypersensitivity to Type I Interferon in Down syndrome

Abstract People with Down syndrome (DS), the genetic condition caused by trisomy of chromosome 21 (chr21), have an altered disease spectrum. For example, adults with DS are largely protected from solid tumors while predisposed to various autoimmune disorders, early-onset Alzheimer’s disease, and severe respiratory infection. While the immune system is known to play a key role in these comorbidities among the disomic population, there is a dearth of immune studies in adults with DS. Here, we applied the single-cell, systems-level approach of mass-cytometry, or Cytometry by Time-Of-Flight (CyTOF), to broadly define phenotypic and functional alterations in immune homeostasis in adults with DS that are relevant to the potentiation of comorbidities associated with T21. We developed an innovative strategy to analyze CyTOF data, by incorporating techniques commonly used in genomics and even topography to eliminate batch bias and efficiently resolve ~100 immune cell types. This approach revealed that adults with DS have global immune dysregulation reminiscent of various inflammatory and autoimmune states enriched among older individuals of the disomic population. Upon stimulation directly ex vivo with Type I Interferon (IFN) and simultaneous detection of diverse phosphorylation events across the lymphoid and myeloid lineages, all immune subsets from individuals with T21 were hyper-responsive, but the degree of response and signaling pathways used varied among specific cell types. Notably, 4 of the 6 IFN receptor subunits for Types I, II, and III IFNs are encoded on chr21. Altogether, these results establish a critical foundation to pursue immune dysregulation and IFN hyperactivity as a driver of the altered disease spectrum in adults with DS.

Women Serum Concentrations of the IL-10 Family of Cytokines and IFN-γ Decrease from the Third Trimester of Pregnancy to Active Labor

Labor is regarded as increased myometrial activity with a regular contractility pattern. At this final stage of pregnancy, myometrial quiescence is lost, accompanied by altered immune homeostasis. It is well known that the interleukin (IL)-10 family of cytokines modulates immunological responses mainly in epithelial cells, including the endometrium. To investigate their inflammatory profile during labor, we performed a longitudinal study in a group of healthy pregnant women (n = 20) with uncomplicated pregnancies in the third trimester of pregnancy and during active labor. Blood was sampled from pregnant women in the third trimester (gestational age 32-38 weeks, mean 36 ± 2 weeks) and during active labor (39-41 weeks of gestation, mean 40 ± 1 weeks). Serum levels of several cytokines were measured using multiplex immunoassays for both stages, indicating that the concentrations of IL-10, IL-20, IL-22, IL-28A, and interferon (IFN)-γ were significantly decreased during active labor in comparison with third-trimester levels (p < 0.05). Our analysis did not find significant correlations between IL-10, IL-20, IL-22, IL-28A, and IFN-γ levels and gestational age. However, our data suggest that the systemic downregulation of several members of the IL-10 family of cytokines plays an important role in the activation of myometrial smooth cells associated with uterine contractions during active labor. Downregulation of this IL-10 family of cytokines seems to coincide with the well-reported functional progesterone withdrawal during labor. Likewise, lower plasma IFN-γ concentrations may indicate a role for IFN-γ in active labor.

Anti-CD137 enhances anti-CD20 therapy of systemic B-cell lymphoma with altered immune homeostasis but negligible toxicity

ABSTRACTStudies of sequential anti-CD137/anti-CD20 therapy have previously shown that the efficacy of anti-CD20 was heavily reliant upon anti-CD137; however, the exact mechanism of the anti-B-cell lymphoma efficacy, and whether this correlates with enhanced adverse effects or toxicity, had not been elucidated. Here, we observed that sequential anti-CD137 administration with anti-CD20 resulted in a synergistic therapy, largely dependent upon Fc receptors (FcR), to prolong survival in an experimental B-cell lymphoma therapy model. Tumor suppression was accompanied by B cell depletion, which was not dependent on one activating FcR. Surprisingly, the B-cell activating factor (BAFF) was elevated in the plasma of mice receiving anti-CD137 alone or in combination with anti-CD20, while a selective increase in some plasma cytokines was also noted and triggered by anti-CD137. These effects were independent of activating FcR. Sustained treatment of advanced lymphoma revealed increased lymphocyte infiltrates into the liver and a significant decrease in the metabolic capability of the liver in mice receiving anti-CD137. Importantly, these effects were not exacerbated in mice receiving the anti-CD20/CD137 combination, and elevations in classical liver damage markers such as alanine aminotransferase (ALT) were less than that caused by the lymphoma itself. Thus, combined anti-CD20/anti-CD137 treatment increases the therapeutic index of anti-CD20 or anti-CD137 alone. These mouse data were corroborated by ongoing clinical development studies to assess safety, tolerability and pharmacodynamic activity of human patients treated by this approach. Together, these data support the use of this sequential antibody therapeutic strategy to improve the efficacy of rituximab in B-cell lymphoma patients.

Early Diagnosis and Hematopoietic Stem Cell Transplantation for IL10R Deficiency Leading to Very Early-Onset Inflammatory Bowel Disease Are Essential in Familial Cases.

Alterations of immune homeostasis in the gut may result in development of inflammatory bowel disease. A five-month-old girl was referred for recurrent respiratory and genitourinary tract infections, sepsis in neonatal period, chronic diarrhea, perianal abscess, rectovaginal fistula, and hyperemic skin lesions. She was born to second-degree consanguineous, healthy parents. Her elder siblings were lost at 4 months of age due to sepsis and 1 year of age due to inflammatory bowel disease, respectively. Absolute neutrophil and lymphocyte counts, immunoglobulin levels, and lymphocyte subsets were normal ruling out severe congenital neutropenia and classic severe combined immunodeficiencies. Quantitative determination of oxidative burst was normal, excluding chronic granulomatous disease. Colonoscopy revealed granulation, ulceration, and pseudopolyps, compatible with colitis. Very early-onset colitis and perianal disease leading to fistula formation suggested probability of inherited deficiencies of IL-10 or IL-10 receptor. A mutation at position c.G477A in exon of the IL10RB gene, resulting in a stop codon at position p.W159X, was identified. The patient underwent myeloablative hematopoietic stem cell transplantation from full matched father at 11 months of age. Perianal lesions, chronic diarrhea, and recurrent infections resolved after transplantation. IL-10/IL-10R deficiencies must be considered in patients with early-onset enterocolitis.

Prenatal exposure to bisphenol-A is associated with Toll-like receptor-induced cytokine suppression in neonates.

Despite widespread human exposure to biphenol A (BPA), limited studies exist on the association of BPA with adverse health outcomes in young children. This study aims to investigate the effect of prenatal exposure to BPA on toll-like receptor-induced cytokine responses in neonates and its association with infectious diseases later in life. Cord bloods were collected from 275 full-term neonates. Production of TNF-α, IL-6, and IL-10 were evaluated after stimulating mononuclear cells with toll-like receptor ligands (TLR1-4 and 7-8). Serum BPA concentrations were analyzed by enzyme-linked immunosorbent assay. Bacteria from nasopharyngeal specimens were identified with multiplex PCR and culture method. Result showed significant association between cord BPA concentration and TLR3- and TLR4-stimulated TNF-α response (P = 0.001) and that of TLR78-stimulated IL-6 response (P = 0.03). Clinical analysis did not show prenatal BPA exposure to be correlated with infection or bacterial colonization during the first year of life. This is the first cohort study that indicated prenatal BPA exposure to play a part in TLR-related innate immune response of neonatal infants. However, despite an altered immune homeostasis, result did not show such exposure to be associated with increased risk of infection during early infancy.

Early-onset inflammatory bowel disease and common variable immunodeficiency–like disease caused by IL-21 deficiency

Alterations of immune homeostasis in the gut can result in development of inflammatory bowel disease (IBD). Recently, Mendelian forms of IBD have been discovered, as exemplified by deficiency of IL-10 or its receptor subunits. In addition, other types of primary immunodeficiency disorders might be associated with intestinal inflammation as one of their leading clinical presentations. We investigated a large consanguineous family with 3 children who presented with early-onset IBD within the first year of life, leading to death in infancy in 2 of them. Homozygosity mapping combined with exome sequencing was performed to identify the molecular cause of the disorder. Functional experiments were performed to assess the effect of IL-21 on the immune system. A homozygous mutation in IL21 was discovered that showed perfect segregation with the disease. Deficiency of IL-21 resulted in reduced numbers of circulating CD19(+) B cells, including IgM(+) naive and class-switched IgG memory B cells, with a concomitant increase in transitional B-cell numbers. In vitro assays demonstrated that mutant IL-21(Leu49Pro) did not induce signal transducer and activator of transcription 3 phosphorylation and immunoglobulin class-switch recombination. Our study uncovers IL-21 deficiency as a novel cause of early-onset IBD in human subjects accompanied by defects in B-cell development similar to those found in patients with common variable immunodeficiency. IBD might mask an underlying primary immunodeficiency, as illustrated here with IL-21 deficiency.

Lessons Learned from the Differential Upregulation of 2?5?-Oligoadenylate Synthetase Genes in Systemic Sclerosis

Precise regulation of the immune system is crucial for homeostasis maintenance. Autoimmunities are complex disorders that have in common alterations in immune homeostasis, and in order to be fully understood approaches that take into consideration their complexity are needed. In systemic sclerosis patients, levels of type I Interferons and 2’5’-oligoadenylate synthetase genes are found upregulated. In 2013, an approach that quantified each individual 2’5’-OAS gene in patients revealed that there is a differential upregulation of this gene family. The hypothesis is that during the disease patient cells are refractory to circulating type I Interferons and that an unknown stimuli is differentially inducing OAS2 and OASL genes. It can be taken as an example that the complexity of the immune system and its components must be taken into consideration to satisfactory understand autoimmunities.

Bacterial infections and vaccines.

We are exposed to multiple pathogens in our lifetime that can localize to body surfaces, spread systemically or both. The characteristics of an individual pathogen influences the type of effective immunity required to control it. For instance, to control helminth infections a pre-dominantly Th2 response is required, whereas control of intracellular pathogens such as Salmonella largely requires a Th1 response. Therefore, upon infection the host mounts an immune response tailored to the given pathogen. The nature and persistence of this response is predictive of the host’s ability to control the infection. Nevertheless, the accumulated impact of exposure to multiple pathogens and the subsequent impact of related activity can have a marked impact on immune homeostasis and function, to the point where the host can have increased susceptibility to additional unrelated infections. This altered immune homeostasis can be due to a combination of one or more factors that include: (i) perturbed barrier function; (ii) ineffective immune cell generation; (iii) defective immune cell trafficking; (iv) inappropriate adaptive cell polarization and (v) impaired cell function. Whichever of these apply, ultimately the impact on the host is often expressed as impaired control of an invading pathogen. Despite the impact multiple infections can have on the host, the relationship between infectious history and immune function after infection and vaccination remains understudied, even though they have a staggering social and economic impact. The reasons for this are manifold but include the importance of studying the infectious process of a single pathogen, the availability of appropriate tools and model organisms to uncover mechanisms. As our understanding of infections caused by individual pathogens increases, it is possible to broaden our focus to look at how distinct infections interact. In this chapter we wish to highlight some advances in our understanding of how infectious history can influence immunity to unrelated pathogens. For this we have focused on the influence of helminths on bacterial infections and immunity to vaccination.

Differential Plasma Cytokine Levels in Patients with and without Chronic Graft-Versus-Host Disease Following Allogeneic Hematopoietic Stem Cell Transplantation

AbstractAbstract 4476Chronic graft-versus-host disease (cGVHD) is a serious and frequent complication of allogeneic hematopoietic stem cell transplantation (HSCT). It is not known why some patients develop cGVHD and others do not, but identifying predictive biomarkers would facilitate the development of pre-emptive therapeutic strategies. Investigation into the pathophysiology of cGVHD has revealed different patterns of immune reconstitution in patients who develop cGVHD following HSCT. This suggests that the development of cGVHD occurs as a result of altered immune homeostasis and the inability to establish B and T cell tolerance. We prospectively examined 88 patients with hematologic malignancies following allogeneic HSCT at the Brigham and Woman’s Hospital/Dana-Farber Cancer Institute between the years 2004 and 2008 and measured plasma cytokines known to modulate effector T cell, regulatory T cell, and B cell homeostasis and function. Seventy-six patients (86%) received reduced intensity conditioning; 84 (95%) received filgrastim-mobilized peripheral blood stem cells. Median follow-up for all patients was 5 years (range 2.9 to 7.3 years). Fifty-nine percent developed cGVHD. Plasma samples were collected at 1, 3, 6, and 12 months after HSCT and multiplex Luminex bead assays were used to measure levels of the following cytokines: Interferon-γ, IL-2, IL-7, IL-1β, IL-12, TNFα, IL-4, IL-5, IL-6, IL-10, and GM-CSF. Cytokine levels in patients who developed cGVHD were compared to patients who did not develop cGVHD. Results are shown in figure 1. Significantly higher levels of IL-4, IL-6, IL-12, and IL-1β were observed at 1 and/or 3 months after transplantation in patients who subsequently developed cGVHD. IL-4 and IL-6 are characteristic of T-helper-2 (TH2) cellular and humoral immune responses previously associated with cGVHD and fibrogenesis. IL-12 and IL-1β have heterogeneous functions including stimulating interferon-γ and TNFα production, enhancing cytotoxic and helper T cells, and promotion of autoimmunity. IL-1α also stimulates IL-6 production and activates fibroblasts. Finally, GM-CSF was significantly elevated in patients who do not develop cGVHD at 1 year following HSCT (2.5 v 1.46 pg/mL, p=0.017). As shown in figure 1, we observed a general pattern for many cytokines, including IFNγ, IL-2, IL-4, IL-5, IL-6, and IL-1β, in which these cytokines are initially similar in both groups, or lower in patients without cGVHD, but gradually increase over time in patients who do not develop cGVHD. In contrast, cytokine levels remain stable in patients with cGVHD and are generally lower 1 year after transplantation in these patients. These late differences may reflect immune suppressive therapies as well as persistent abnormalities of immune homeostasis. Taken together, these results support the hypothesis that alterations in immune homeostasis early after allogeneic HSCT are significantly associated with the subsequent development of cGVHD. Manipulation of the cytokine environment early after HSCT can modulate immune homeostasis and may be of potential prophylactic value. Administration of homeostatic cytokines late after HSCT may also have therapeutic benefit. [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Interactions Between Intestinal Microbiota and Innate Immune System in Pediatric Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is the result of an altered immune homeostasis within the intestinal mucosa against the gut microbiota, leading to chronic inflammation in genetically predisposed individuals. Under normal conditions, the immune system defends against pathogens and prevents the passage of excessive intestinal bacteria; regulatory pathways must maintain a low-grade, controlled inflammation in a healthy gut, but also induce a protective response against pathogens. The innate immune system is the first-line defense from microbes; dendritic cells, macrophages, and epithelial cells produce an initial, immediate response. The immune system constantly controls commensal bacteria and utilizes constitutive antimicrobial mechanisms to sustain immune homeostasis. The discovery that several genes linked to IBD modulate microbial recognition and innate immune pathways, such as nucleotide oligomerization domain 2 (Nod2), and genes that mediate autophagy (ie, ATG16L1, IRGM), has highlighted the critical role of host-microbe interactions in controlling intestinal immune homeostasis. Commensal microorganisms actively interact with the intestinal mucosa and influence the activity of the immune system as well as the amplitude of the immune response. In contrast, host factors can influence microbes, which in turn modulate disease susceptibility. In this paper, we focus on the mechanisms that mediate host-microbe interactions and how the disruption of this balance leads to chronic intestinal inflammation in IBD.