Plasma levels of intestinal fatty-acid binding protein (I-FABP), abdominal distension and hydrogen concentration after lactitol small intestinal bacterial overgrowth (SIBO) test

Breath tests with glucose, lactulose or lactitol are useful for diagnosis of small intestinal bacterial overgrowth (SIBO). Nevertheless, they have suboptimal sensitivity and specificity and, indeed, are positive in a considerable number of patients with irritable bowel syndrome (IBS). The complexity in the management of patients with functional intestinal disorders and the availability of these tests are leading to frequent diagnoses of SIBO. Intestinal Fatty-Acid Binding protein (I-FABP) is a protein present in the cytosol of intestinal epithelial cells. Its plasmatic levels have been related to different enteropathies and, therefore, could be a marker of early intestinal damage with unconfirmed clinical utility. Hence, we have studied the plasmatic I-FABP level of patients who are requested a lactitol test to confirm SIBO and related it to clinical and laboratory characteristics and SIBO test results.

Insulin-degrading enzyme (IDE) as a modulator of microglial phenotypes in the context of Alzheimer's disease and brain aging

The insulin-degrading enzyme (IDE) is an evolutionarily conserved zinc-dependent metallopeptidase highly expressed in the brain, where its specific functions remain poorly understood. Besides insulin, IDE is able to cleave many substrates in vitro, including amyloid beta peptides, making this enzyme a candidate pathophysiological link between Alzheimer's disease (AD) and type 2 diabetes (T2D). These antecedents led us to address the impact of IDE absence in hippocampus and olfactory bulb. A specific induction of microgliosis was found in the hippocampus of IDE knockout (IDE-KO) mice, without any effects in neither hippocampal volume nor astrogliosis. Performance on hippocampal-dependent memory tests is influenced by IDE gene dose in 12-month-old mice. Furthermore, a comprehensive characterization of the impact of IDE haploinsufficiency and total deletion in metabolic, behavioral, and molecular parameters in the olfactory bulb, a site of high insulin receptor levels, reveals an unambiguous barcode for IDE-KO mice at that age. Using wildtype and IDE-KO primary microglial cultures, we performed a functional analysis at the cellular level. IDE absence alters microglial responses to environmental signals, resulting in impaired modulation of phenotypic states, with only transitory effects on amyloid-β management. Collectively, our results reveal previously unknown physiological functions for IDE in microglia that, due to cell-compartment topological reasons, cannot be explained by its enzymatic activity, but instead modulate their multidimensional response to various damaging conditions relevant to aging and AD conditions.

Study and isolation of human intestinal dendritic cell and macrophage subsets

Dendritic cells and macrophages are the main antigen-presenting cells (APC). In the gut, they control the mechanisms of tolerance toward commensals and nutrients, at the time that they maintain their capacity to trigger immune responses against invading pathogens. Nevertheless, this balance is not perfect as it can get disrupted like in inflammatory bowel disease (where they drive an abnormal immune response against the microbiota) or in coeliac disease (where they trigger an immune response against dietary gluten). Therefore, the study of human intestinal APC subsets is crucial not just to get a deeper insight in the mechanisms of human intestinal homeostasis, but also to understand the pathogenesis of inflammatory bowel disease and coeliac disease. Nevertheless, their study is quite complicated as despite their relevance, their numbers are scare in the intestinal mucosa. Therefore, we hereby describe different approaches to study human intestinal dendritic cell and macrophage subsets in the human intestinal mucosa.

Evolutionary Origin of Insulin-Degrading Enzyme and Its Subcellular Localization and Secretion Mechanism: A Study in Microglial Cells

The insulin-degrading enzyme (IDE) is a zinc-dependent metalloendopeptidase that belongs to the M16A metalloprotease family. IDE is markedly expressed in the brain, where it is particularly relevant due to its in vitro amyloid beta (Aβ)-degrading activity. The subcellular localization of IDE, a paramount aspect to understand how this enzyme can perform its proteolytic functions in vivo, remains highly controversial. In this work, we addressed IDE subcellular localization from an evolutionary perspective. Phylogenetic analyses based on protein sequence and gene and protein structure were performed. An in silico analysis of IDE signal peptide suggests an evolutionary shift in IDE exportation at the prokaryote/eukaryote divide. Subcellular localization experiments in microglia revealed that IDE is mostly cytosolic. Furthermore, IDE associates to membranes by their cytoplasmatic side and further partitions between raft and non-raft domains. When stimulated, microglia change into a secretory active state, produces numerous multivesicular bodies and IDE associates with their membranes. The subsequent inward budding of such membranes internalizes IDE in intraluminal vesicles, which later allows IDE to be exported outside the cells in small extracellular vesicles. We further demonstrate that such an IDE exportation mechanism is regulated by stimuli relevant for microglia in physiological conditions and upon aging and neurodegeneration.

Guidelines for the use of flow cytometry and cell sorting in immunological studies (third edition)

The third edition of Flow Cytometry Guidelines provides the key aspects to consider when performing flow cytometry experiments and includes comprehensive sections describing phenotypes and functional assays of all major human and murine immune cell subsets. Notably, the Guidelines contain helpful tables highlighting phenotypes and key differences between human and murine cells. Another useful feature of this edition is the flow cytometry analysis of clinical samples with examples of flow cytometry applications in the context of autoimmune diseases, cancers as well as acute and chronic infectious diseases. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid. All sections are written and peer-reviewed by leading flow cytometry experts and immunologists, making this edition an essential and state-of-the-art handbook for basic and clinical researchers.

Human intestinal dendritic cell and macrophage subsets in coeliac disease

Dendritic cells (DC) and macrophages (Mϕ) constitute the most abundant antigen presenting cells in the human intestinal mucosa. In resting conditions, they are essential to maintain the mechanisms of immune tolerance toward food antigens and commensals, at the time that they keep the capacity to initiate and maintain antigen-specific pro-inflammatory immune responses toward invading pathogens. Nevertheless, this delicate equilibrium between immunity and tolerance is not perfect, like in coeliac disease (CD), where DC and Mϕ drive the development of antigen-specific immune responses toward dietary gluten peptides. In this review, we provide therefore a comprehensive discussion about CD pathogenesis, the human intestinal immune system and the biology of intestinal DC and Mϕ both in resting conditions and in CD. Last, but not least, we discuss about all the remaining issues pending to be studied regarding DC and Mϕ contribution toward CD pathogenesis. This may allow the identification of unique and specific factors which may be useful in the clinical practice, as well as identify new therapeutic targets in order to reestablish the loss intestinal homeostasis in CD.

Modulation of Glial Responses by Furanocembranolides: Leptolide Diminishes Microglial Inflammation in Vitro and Ameliorates Gliosis In Vivo in a Mouse Model of Obesity and Insulin Resistance

Neurodegenerative diseases are age-related disorders caused by progressive neuronal death in different regions of the nervous system. Neuroinflammation, modulated by glial cells, is a crucial event during the neurodegenerative process; consequently, there is an urgency to find new therapeutic products with anti-glioinflammatory properties. Five new furanocembranolides (1-5), along with leptolide, were isolated from two different extracts of Leptogorgia sp., and compound 6 was obtained from chemical transformation of leptolide. Their structures were determined based on spectroscopic evidence. These seven furanocembranolides were screened in vitro by measuring their ability to modulate interleukin-1β (IL-1β) production by microglial BV2 cells after LPS (lipopolysaccharide) stimulation. Leptolide and compounds 3, 4 and 6 exhibited clear anti-inflammatory effects on microglial cells, while compound 2 presented a pro-inflammatory outcome. The in vitro results prompted us to assess anti-glioinflammatory effects of leptolide in vivo in a high-fat diet-induced obese mouse model. Interestingly, leptolide treatment ameliorated both microgliosis and astrogliosis in this animal model. Taken together, our results reveal a promising direct biological effect of furanocembranolides on microglial cells as bioactive anti-inflammatory molecules. Among them, leptolide provides us a feasible therapeutic approach to treat neuroinflammation concomitant with metabolic impairment.

Different Intraepithelial CD3+ Cell Numbers in Crohn's Disease and Ulcerative Colitis

Intraepithelial immune response can be studied by flow cytometry. The proportion of CD3+ cells differs between Crohn’s disease and ulcerative colitis.

Circulating Dendritic Cells from Celiac Disease Patients Display a Gut-Homing Profile and are Differentially Modulated by Different Gliadin-Derived Peptides

SCOPE

Circulating dendritic cell (DC) and monocyte subsets contribute to the pool of intestinal DC and macrophages in celiac disease (CeD), an autoimmune gut disorder triggered by dietary gluten. Here, this study aims to characterize these circulating subsets in CeD and assess the effect of different gliadin-derived peptides on conventional DC (cDC).

METHODS AND RESULTS

Flow cytometry profiling of peripheral blood mononuclear cells reveals a slight decrease in the proportion of plasmacytoid and type 1 cDC in gluten-free diet (GFD)-treated CeD patients. In comparison to healthy donors, DC and monocyte subsets from active and GFD-treated CeD patients display an increased gut-homing profile. Type 2 cDC (cDC2) are sorted and stimulated with the gliadin-derived peptides 8-mer, 19-mer, and 33-mer. All peptides induce cDC2 maturation, although the profile is different. While peptide 8-mer induces a Th1/Th17 pro-inflammatory cytokine profile in active CeD patients, cDC2 primed with peptide 33-mer displays a higher capacity to promote gut-homing CCR9⁺ expression onto autologous T-cells.

CONCLUSION

Distinct gliadin-derived peptides elicit different effects on cDC2 phenotype and function. This effect is compatible with a model where diverse gliadin peptides may cooperate to promote full cDC2 activation and the subsequent T-cell response in genetically predisposed individuals.

Nanoemulsions and acidified milk gels as a strategy for improving stability and antioxidant activity of yarrow phenolic compounds after gastrointestinal digestion

The aim of this study was to improve the stability and antioxidant activity of yarrow phenolic compounds upon an in vitro simulated gastrointestinal digestion. Therefore, two types of caseins-based delivery systems, sodium caseinate stabilized nanoemulsions (NEs) and glucono delta-lactone acidified milk gels (MGs), were formulated containing an ultrasound-assisted yarrow extract (YE) at two concentrations (1 and 2.5 mg/mL). Formulations with 1 mg/mL of YE were chosen based on their higher encapsulation efficiency to perform the in vitro digestion experiments. After digestion, YE-loaded NEs only partially protected phenolic compounds from degradation; meanwhile the phenolic composition of YE including in MGs after digestion was quite similar to undigested YE. Moreover, the antioxidant activity of MGs after digestion was higher than NEs digested samples, which confirms the higher protection of YE phenolic compound by the milk gels systems. This research demonstrated the potential use of acidified MGs as carriers to improve the stability and antioxidant activity of yarrow phenolic compounds. Therefore, these matrices could be employed to develop new dairy products enriched with phenolic compounds.

Is celiac disease really associated with inflammatory bowel disease?

Celiac disease (CeD) and inflammatory bowel disease (IBD) are chronic gastrointestinal disorders of inflammatory origin that develop in response to environmental triggers in genetically predisposed individuals. CeD localizes in the duodenal mucosa, where intolerance develops to dietary gluten from wheat, barley, rye, and some varieties of oats. IBD, in turn, is subdivided primarily into Crohn's disease (CD) and colitis, with ulcerative colitis (UC) being the most thoroughly investigated form.

Effect of milk protein composition and amount of β-casein on growth performance, gut hormones, and inflammatory cytokines in an in vivo piglet model

The objective of this work was to better understand the effect of differences in milk protein composition, and specifically, a change in β-casein to total casein in a milk-based matrix, on growth performance and metabolic and inflammatory responses using a piglet model. Three formulas were optimized for piglets, with similar metabolizable energy, total protein content, and other essential nutrients. Only the protein type and ratio varied between the treatments: the protein fraction of the control diet contained only whey proteins, whereas 2 other matrices contained a whey protein to casein ratio of 60:40, and differed in the amount of β-casein (12.5 and 17.1% of total protein). Piglets fed formula containing whey proteins and caseins, regardless of the concentration of β-casein, showed a significantly higher average daily gain, average daily feed intake, and feed efficiency compared with piglets consuming the formula with only whey protein. Consumption of the formula containing only whey protein showed higher levels of plasma glucagon-like peptide-1 and ghrelin compared with the consumption of formula containing casein and whey protein. A positive correlation was observed between postprandial time and glucagon-like peptide-1 response. The intestinal pro-inflammatory cytokine tumor necrosis factor α increased significantly in piglets fed the whey protein/casein diet compared with those fed whey protein formula. All formula-fed piglets showed a lower level of IL-6 cytokine compared with the ad libitum sow-fed piglets, regardless of composition. No significant differences in the anti-inflammatory IL-10 concentration were observed between treatment groups. Milk protein composition contributed to the regulation of piglets' metabolic and physiological responses, with whey protein/casein formula promoting growth performance and a different immune regulatory balance compared with a formula containing only whey protein. Results indicated no differences between treatments containing different levels of β-casein.

Effect of protein composition of a model dairy matrix containing various levels of beta-casein on the structure and anti-inflammatory activity of in vitro digestates

An increasing body of evidence demonstrates that differences in protein composition in the food matrix can significantly affect its biological functionality. The present research hypothesized that a matrix containing the same level of dairy protein, but with different composition, even when showing similar properties during digestion, may have a different biological functionality. To test this hypothesis, three matrices, containing 2.8% protein and similar amounts of fat and solid were prepared, either with 100% whey proteins, or with a ratio of caseins to whey protein of 40 : 60, but differing in β-casein ratio. The mixtures were subjected to in vitro digestion, and the digestates were used in uptake experiments using Caco-2 cell monolayers. The basolateral fraction metabolized by the cells was used to stimulate human LPS-stimulated THP-1 macrophages and the concentration of selected cytokines were measured, as an indication of potential differences in biological functionality between the different dairy matrices. All three digestates induced a significant reduction in IL-1β cytokines, with the casein-containing treatments inducing a greater decrease compared to that containing only whey proteins. The matrix containing the highest ratio of β-casein induced the lowest secretion of proinflammatory cytokines TNF-a and IL-6. This study demonstrated that milk protein composition does not only affect the rate of gastric proteolysis and structure of the gastric digestate, but will cause differences in physiological effects. This research stressed the role of milk protein components during digestion, and of β-casein in particular, and their potential to modulate biological functions in the gastrointestinal tract.

Recommendations to report and interpret HLA genetic findings in coeliac disease

Coeliac disease (CD) is a chronic autoimmune enteropathy triggered by gluten and related prolamines in genetically predisposed individuals. Although CD is a polygenic disease, there is a strong association with genes of the human leukocyte antigen (HLA) region. Most patients present the HLA-DQ2 heterodimer, specifically the DQ2.5 isoform, which is present in around 90-96% of patients of European ancestry.

Invited review: Milk phospholipid vesicles, their colloidal properties, and potential as delivery vehicles for bioactive molecules

The milk fat globule membrane (MFGM) is a unique colloidal assembly of phospholipids and proteins, with numerous potential applications as functional ingredient. The phospholipid components of the MFGM are gaining interest as they are a useful matrix for use as a constituent of delivery systems such as liposomes. Liposomes formulated with milk phospholipids are becoming an alternative to other sources of phospholipids such as soybean or egg yolk. However, incorporation of phospholipids fractionated from the milk fat globule membrane in dairy products requires an in-depth understanding of the functional properties of phospholipids. In particular, it is critical to understand which factors play a role in their stability and bioefficacy as delivery systems. Moreover, chemical and physical modifications of phospholipid liposomes occurring during digestion and the fate of the encapsulated compounds are very important to understand. This review discusses recent findings on the structure and functionality of MFGM, the bioactivity of the phospholipids fraction, their utilization as delivery systems, and their stability through gastrointestinal transit.

New IL-15 receptor-α splicing variants identified in intestinal epithelial Caco-2 cells

IL-15 is a pleiotropic cytokine related to IL-2 which acts at a broader level than its counterpart. It is presented through its specific high-affinity receptor, IL-15Rα. Both cytokine and receptor are tightly regulated at multiple levels and are widely distributed. Thus, deregulation of their expression leads to an inflammatory immune response. Variants of splicing of IL-15Rα have been described in immune and barrier cells; however, their presence has not been focused on intestinal epithelial cells. In this study, we describe five new alternative variants of splicing of IL-15Rα in Caco-2 cells. Four of them were expressed into proteins inside Caco-2 cells, but these were unable to bind IL-15 or to follow the secretory pathway. However, the expression of mRNA itself might be relevant to diseases such as celiac disease, inflammatory bowel disease or colorectal cancer.

Chemokine (C-C Motif) Receptor 2 Mediates Dendritic Cell Recruitment to the Human Colon but Is Not Responsible for Differences Observed in Dendritic Cell Subsets, Phenotype, and Function Between the Proximal and Distal Colon

BACKGROUND & AIMS

Most knowledge about gastrointestinal (GI)-tract dendritic cells (DC) relies on murine studies where CD103⁺ DC specialize in generating immune tolerance with the functionality of CD11b^+/- subsets being unclear. Information about human GI-DC is scarce, especially regarding regional specifications. Here, we characterized human DC properties throughout the human colon.

METHODS

Paired proximal (right/ascending) and distal (left/descending) human colonic biopsies from 95 healthy subjects were taken; DC were assessed by flow cytometry and microbiota composition assessed by 16S rRNA gene sequencing.

RESULTS

Colonic DC identified were myeloid (mDC, CD11c⁺CD123^-) and further divided based on CD103 and SIRPα (human analog of murine CD11b) expression. CD103^-SIRPα⁺ DC were the major population and with CD103⁺SIRPα⁺ DC were CD1c⁺ILT3⁺CCR2⁺ (although CCR2 was not expressed on all CD103⁺SIRPα⁺ DC). CD103⁺SIRPα^- DC constituted a minor subset that were CD141⁺ILT3^-CCR2^-. Proximal colon samples had higher total DC counts and fewer CD103⁺SIRPα⁺ cells. Proximal colon DC were more mature than distal DC with higher stimulatory capacity for CD4⁺CD45RA⁺ T-cells. However, DC and DC-invoked T-cell expression of mucosal homing markers (β7, CCR9) was lower for proximal DC. CCR2 was expressed on circulating CD1c⁺, but not CD141⁺ mDC, and mediated DC recruitment by colonic culture supernatants in transwell assays. Proximal colon DC produced higher levels of cytokines. Mucosal microbiota profiling showed a lower microbiota load in the proximal colon, but with no differences in microbiota composition between compartments.

CONCLUSIONS

Proximal colonic DC subsets differ from those in distal colon and are more mature. Targeted immunotherapy using DC in T-cell mediated GI tract inflammation may therefore need to reflect this immune compartmentalization.

Atypical IgM multiple myeloma with deletion of c-MAF

IgM multiple myeloma (MM) is a rare subtype of myeloma that shares clinical and pathological features with Waldenström's macroglobulinaemia. These are two separate entities that differ both in therapy and prognosis. We report a 57-year-old male, who presented with anaemia, hypercalcaemia, acute renal failure and several vertebral fractures that clinically suggested a multiple myeloma. Further investigations revealed a serum monoclonal component of IgM lambda type and a bone marrow infiltrated by small, lymphoplasmocytic cells. IgM MM was finally diagnosed by means of both inmunophenotypic and immunohistochemistry techniques, stressing the importance of inmunophenotypic evaluation when clinical and morphological features are discordant. Fluorescence in situ hybridization (FISH) studies disclosed a particular combination of deletion 13q14, t(11;14) and monoallelic deletion C-MAF without t(14;16). The clinical evolution after a Bortezomib-containing polychemotherapy and autologous stem cell transplantation (ASCT) conditioned with busulphan and melphalan is also presented. This very uncommon case highlights the impact of immunophenotyping on the differential diagnosis between IgM MM and WM, to choose the best treatment and establish an appropriate outcome.

Human colon-derived soluble factors modulate gut microbiota composition

The commensal microbiota modulates immunological and metabolic aspects of the intestinal mucosa contributing to development of human gut diseases including inflammatory bowel disease. The host/microbiota interaction often referred to as a crosstalk, mainly focuses on the effect of the microbiota on the host neglecting effects that the host could elicit on the commensals. Colonic microenvironments from three human healthy controls (obtained from the proximal and distal colon, both in resting conditions and after immune – IL-15- and microbiota – LPS-in vitro challenges) were used to condition a stable fecal population. Subsequent 16S rRNA gene-based analyses were performed to study the effect induced by the host on the microbiota composition and function. Non-supervised principal component analysis (PCA) showed that all microbiotas, which had been conditioned with colonic microenvironments clustered together in terms of relative microbial composition, suggesting that soluble factors were modulating a stable fecal population independently from the treatment or the origin. Our findings confirmed that the host intestinal microenvironment has the capacity to modulate the gut microbiota composition via yet unidentified soluble factors. These findings indicate that an appropriate understanding of the factors of the host mucosal microenvironment affecting microbiota composition and function could improve therapeutic manipulation of the microbiota composition.

Innate lymphoid cells and natural killer T cells in the gastrointestinal tract immune system

The gastrointestinal tract is equipped with a highly specialized intrinsic immune system. However, the intestine is exposed to a high antigenic burden that requires a fast, nonspecific response -so-called innate immunity- to maintain homeostasis and protect the body from incoming pathogens. In the last decade multiple studies helped to unravel the particular developmental requirements and specific functions of the cells that play a role in innate immunity. In this review we shall focus on innate lymphoid cells, a newly discovered, heterogeneous set of cells that derive from an Id2-dependent lymphoid progenitor cell population. These cells have been categorized on the basis of the pattern of cytokines that they secrete, and the transcription factors that regulate their development and functions. Innate lymphoid cells play a role in the early response to pathogens, the anatomical contention of the commensal flora, and the maintenance of epithelial integrity.Amongst the various innate lymphoid cells we shall lay emphasis on a subpopulation with several peculiarities, namely that of natural killer T cells, a subset of T lymphocytes that express both T-cell and NK-cell receptors. The most numerous fraction of the NKT population are the so-called invariant NKT or iNKT cells. These iNKT cells have an invariant TCR and recognize the glycolipidic structures presented by the CD1d molecule, a homolog of class-I MHC molecules. Following activation they rapidly acquire cytotoxic activity and secrete both Th1 and Th2 cytokines, including IL-17. While their specific role is not yet established, iNKT cells take part in a great variety of intestinal immune responses ranging from oral tolerance to involvement in a number of gastrointestinal conditions.

Autoantibodies against MHC class I polypeptide-related sequence A are associated with increased risk of concomitant autoimmune diseases in celiac patients

BACKGROUND

Overexpression of autologous proteins can lead to the formation of autoantibodies and autoimmune diseases. MHC class I polypeptide-related sequence A (MICA) is highly expressed in the enterocytes of patients with celiac disease, which arises in response to gluten. The aim of this study was to investigate anti-MICA antibody formation in patients with celiac disease and its association with other autoimmune processes.

METHODS

We tested serum samples from 383 patients with celiac disease, obtained before they took up a gluten-free diet, 428 patients with diverse autoimmune diseases, and 200 controls for anti-MICA antibodies. All samples were also tested for anti-endomysium and anti-transglutaminase antibodies.

RESULTS

Antibodies against MICA were detected in samples from 41.7% of patients with celiac disease but in only 3.5% of those from controls (P <0.0001) and 8.2% from patients with autoimmune disease (P <0.0001). These antibodies disappeared after the instauration of a gluten-free diet. Anti-MICA antibodies were significantly prevalent in younger patients (P <0.01). Fifty-eight patients with celiac disease (15.1%) presented a concomitant autoimmune disease. Anti-MICA-positive patients had a higher risk of autoimmune disease than MICA antibody-negative patients (P <0.0001; odds ratio = 6.11). The risk was even higher when we also controlled for age (odds ratio = 11.69). Finally, we found that the associated risk of developing additional autoimmune diseases was 16 and 10 times as high in pediatric patients and adults with anti-MICA, respectively, as in those without.

CONCLUSIONS

The development of anti-MICA antibodies could be related to a gluten-containing diet, and seems to be involved in the development of autoimmune diseases in patients with celiac disease, especially younger ones.

Detection of specific IgA antibodies against a novel deamidated 8-Mer gliadin peptide in blood plasma samples from celiac patients

We studied whether celiac disease (CD) patients produce antibodies against a novel gliadin peptide specifically generated in the duodenum of CD patients by a previously described pattern of CD-specific duodenal proteases. Fingerprinting and ion-trap mass spectrometry of CD-specific duodenal gliadin-degrading protease pattern revealed a new 8-mer gliadin-derived peptide. An ELISA against synthetic deamidated 8-mer peptides (DGP 8-mer) was used to study the presence of IgA anti-DGP 8-mer antibodies in plasma samples from 81 children (31 active CD patients (aCD), 17 CD patients on a gluten-free diet (GFD), 10 healthy controls (C) and 23 patients with other gastrointestinal pathology (GP)) and 101 adults (16 aCD, 12 GFD, 27 C and 46 GP-patients). Deamidation of the 8-mer peptide significantly increased the reactivity of the IgA antibodies from CD patients against the peptide. Significant IgA anti-DGP 8-mer antibodies levels were detected in 93.5% of aCD-, 11.8% of GFD- and 4.3% of GP-patients in children. In adults, antibodies were detected in 81.3% of aCD-patients and 8.3% of GFD-patients while were absent in 100% of C- and GP-patients. Duodenal CD-specific gliadin degrading proteases release an 8-mer gliadin peptide that once deamidated is an antigen for specific IgA antibodies in CD patients which may provide a new accurate diagnostic tool in CD.

IL-6 promotes immune responses in human ulcerative colitis and induces a skin-homing phenotype in the dendritic cells and Tcells they stimulate

Dendritic cells (DCs) control the type and location of immune responses. Ulcerative colitis (UC) is considered a Th2 disease mediated by IL-13 where up to one third of patients can develop extraintestinal manifestations. Colonic biopsies from inflamed and noninflamed areas of UC patients were cultured in vitro and their supernatants were used to condition human blood enriched DCs from healthy controls. Levels of IL-13 in the culture supernatants were below the detection limit in most cases and the cytokine profile suggested a mixed profile rather than a Th2 cytokine profile. IL-6 was the predominant cytokine found in inflamed areas from UC patients and its concentration correlated with the Mayo endoscopic score for severity of disease. DCs conditioned with noninflamed culture supernatants acquired a regulatory phenotype with decreased stimulatory capacity. However, DCs conditioned with inflamed culture supernatants acquired a proinflammatory phenotype with increased expression of the skin-homing chemokine CCR8. These DCs did not have decreased T-cell stimulatory capacity and primed T cells with the skin-homing CLA molecule in an IL-6-dependent mechanism. Our results highlight the role of IL-6 in UC and question the concept of UC as a Th2 disease and the relevance of IL-13 in its etiology.

Ascorbate-dependent decrease of the mucosal immune inflammatory response to gliadin in coeliac disease patients

BACKGROUND

The IL-15/NF-κB axis has an important role in coeliac disease (CD) and may represent a molecular target for immunomodulation. Ascorbate (vitamin C) is known to show inhibitory effects on NF-κB. Therefore, we studied if ascorbate supplementation to gliadin gliadin-stimulated biopsy culture could down-regulate the mucosal immune response to gliadin in CD.

METHODS

Duodenal biopsy explants from treated CD patients were gliadin challenged in vitro (100 μg/ml) with and without 20mM ascorbate. An extra tissue explant in basal culture was used as internal control. Secretion levels of nitrites (3h), and IFNγ, TNFα, IFNα, IL-17, IL-13, and IL-6 (24h) were measured on the supernatants. IL-15 was assayed by western-blot on whole protein duodenal explants.

RESULTS

The addition of ascorbate to in vitro culture gliadin-challenged biopsies blocked the secretion of nitrites (p=0.013), IFNγ (p=0.0207), TNFα (p=0.0099), IFNα (p=0.0375), and IL-6 (p=0.0036) compared to samples from non-ascorbate supplemented culture. Cytokine secretion was downregulated by ascorbate even to lower values than those observed in basal cultures (IFNγ: p=0.0312; TNFα: p=0.0312; IFNα: p=0.0312; and IL-6: p=0.0078). Gliadin-challenge induced IL-15 production in biopsies from treated CD patients, while the addition of ascorbate to culture medium completely inhibited IL-15 production. Moreover, the inhibition of IL-15 by ascorbate took place even in the only treated CD-patient who had basal IL-15 production.

CONCLUSIONS

Ascorbate decreases the mucosal inflammatory response to gluten in an intestinal biopsy culture model, so it might have a role in future supplementary therapy in CD.

IL-15 modulates the effect of retinoic acid, promoting inflammation rather than oral tolerance to dietary antigens

The physiological immune response in the intestine against dietary proteins and commensal flora is characterized by regulatory mechanisms (tolerance) that prevent harmful consequences. Intestinal dendritic cells (DCs) have a central role in the development of immunosuppressive regulatory T cells owing to their ability to produce TGF-β and retinoic acid (RA). However, the article under evaluation shows an unexpected effect of RA - that of promoting a proinflammatory phenotype in intestinal DCs involved in the generation of inflammatory immune responses to dietary antigens. By using a double transgenic murine model that resembles human celiac disease, it was demonstrated that RA synergizes with IL-15 in promoting the breakdown of gluten tolerance and the development of enteropathy. The tissue microenvironment modulates DC function, and immune therapies that are based on RA aiming to restore oral tolerance should be used with caution because the presence of IL-15 (and/or other proinflammatory cytokines) may have undesirable effects.

[Interleukin 18 (IL-18) and other immunological parameters as markers of severity in acute pancreatitis]

OBJECTIVE

Our aim was to prospectively compare the behavior of interleukin 18 (IL-18) levels and other immunological parameters during the first week of hospitalization between acute pancreatitis patients with and without severity criteria, as well as between patients with and without late pseudocyst development.

PATIENTS AND METHODS

In 36 patients with acute pancreatis we compared sTNF-RI, IL-1Ra, IL-6, and IL-18 levels at days 1, 2, 3 and 7 after hospitalization between mild pancreatitis, severe pancreatitis, and a "control" group (13 patients) with uncomplicated biliary colic, as well as between patients with and without pseudocyst.

RESULTS

On comparing mild to severe pancreatitis, IL-18 was significantly higher only the first day in severe pancreatitis, while the other parameters were steadily higher after the second day. In patients developing pseudocyst, IL-18 was also noticeably higher the first day.

CONCLUSIONS

IL-18 appears to be the earliest marker of complications and severity in acute pancreatitis at both the systemic and local level (pseudocyst).

Allergy after inhalation and ingestion of cereals involve different allergens in allergic and celiac disease

Cereals are among the major foods in type I food hypersensitivity reactions. Hypoallergenic cereals and recombinant immunotherapy have been recently patented. In celiac disease, limited information is available regarding cereal allergens responsible for allergic reactions. The allergenic reactivity of ingested and inhaled cereal allergens in allergic and celiac people are discussed in the manuscript. Allergic sensitisation IgE mediated to cereals may be observed in celiac children. Inhalation and ingestion routes causing cereal allergy seem to involve similar allergens, but, in celiac disease specific response to CM3 may be important.

Higher constitutive IL15R alpha expression and lower IL-15 response threshold in coeliac disease patients

The IL-15 triggering effect of gliadin is not exclusive to coeliac disease (CD) patients, whereas the secondary response is CD specific. We have studied the expression of the IL-15 receptor, and the IL-15 response upon stimulation, in non-CD and CD patients, and the possible existence of a lower immunological threshold in the latter. Forty-two CD patients (20 on a gluten-containing diet, GCD, and 22 on gluten-free diet, GFD) and 24 non-CD healthy individuals were studied. IL15R alpha mRNA expression, and tissue characterization, were assayed in the duodenum. Biopsies from six CD patients on GFD and 10 non-CD individuals were studied in vitro using organ culture in basal conditions, as well as after IL-15 stimulation discarding basal IL-15 production. Secretion of immune mediators was measured in the culture supernatants. IL15R alpha mRNA expression was increased in CD patients, as compared with non-CD controls (on GFD P = 0.0334, on GCD P = 0.0062, respectively), and confirmed also by immunofluorescence. No differences were found between CD patients on GFD and on GCD. After in vitro IL-15 stimulation, IL15R alpha expression was only triggered in non-CD controls (P = 0.0313), though it remained increased in CD patients. Moreover, IL-15 induced a more intense immunological response in CD patients after triggering the production of both nitrites and IFN gamma (P = 0.0313, P = 0.0313, respectively). Gliadin-induced IL15 has a lower response threshold in CD patients, leading to the production of other immune mediators and the development of the intestinal lesion, and thus magnifying its effects within the CD intestine.

Predominance of Th2 cytokines, CXC chemokines and innate immunity mediators at the mucosal level during severe respiratory syncytial virus infection in children

Profiling of immune mediators in both nasal and plasma samples is a common approach to the study of pathogenesis in respiratory viral infections. Nevertheless, mucosal immunity functions essentially independently from peripheral immunity. In our study, 27 immune mediators were profiled in parallel, in nasopharyngeal aspirates (NPAs) and plasma from 22 < 2 year-old children with a severe respiratory syncytial virus infection involving the lower respiratory tract, using a multiplex assay. NPAs from 22 children with innocent heart murmurs were used as controls. Differences in mediator concentrations between NPAs from patients and controls were assessed using the Mann-Whitney test. Ratios of innate/adaptive-immunity mediators, Th2/Th1-cytokines and CXC/CC-chemokines were calculated for NPAs and plasmas and differences were assessed using the Wilcoxon test. Associations mediators, severity and leukocyte counts were studied using the Spearman-Karber test.

RESULTS

increased levels of Th1 cytokines (IL-1beta, IL-2, IL-12p70, IFNgamma, TNFalpha), Th2 cytokines (IL-13, IL-4, IL-6, IL-10), chemokines (IP-10, IL-8, MIP1alpha, MIP-1beta), growth factors (FGFb, PDGFbb, GCSF) and IL-1RA, IL-17 were observed in patient NPAs in comparison to controls. In the relative comparisons between patient NPAs and plasmas, a predominance of innate immunity mediators, Th2 cytokines and CXC chemokines was found at the mucosal level. No association between the level of each mediator in NPAs and plasma was found. In plasma, PDGFbb, VEGF, MIP-1alpha, IL-8 correlated with severity; RANTES and IL-6 correlated with leukocyte counts.

CONCLUSIONS

acute respiratory syncytial virus infection induces a relative predominance of innate-immunity mediators, Th2 cytokines and CXC chemokines in the mucosal compartment in infected children.

[Cytokines and other immunological parameters as markers of distant organ involvement in acute pancreatitis]

BACKGROUND AND OBJECTIVE

There is a role of immunologic proinflammatory mediators in pathogenesis of distant organ disfunction in acute pancreatitis (AP). The aim is to evaluate the relationship between those mediators and liver, kidney and lung disfunction in patients with AP.

PATIENTS AND METHOD

On the day of admission in 34 patients with AP, biochemical parameters of liver function, creatinine and arterial partial pressure of oxygen (PO2) were determined, and cut points were established. Soluble tumor necrosis factor receptor I (sTNFRI), interleukin (IL) 1 receptor antagonist (IL-1Ra), IL-6, soluble IL-6 receptor (sIL-6R), IL-18, and intercellular adhesion molecule-1 (ICAM-1) were determined on days 1, 2, 3 and 7, and were compared between patients with biochemical parameters and PO2 on admission higher or lower than an established cut point.

RESULTS

Levels of sTNFRI, IL-18 and ICAM-1 were significantly higher and sustained, and IL-6 only the first day, in patients with parameters of liver function above the cut point. sTNFRI, IL-1Ra and ICAM-1 early showed significantly higher levels in relation with serum creatinine, and these and also IL-6 in those with PO2 below 60 mmHg.

CONCLUSIONS

sTNFRI, IL-6, IL-18 and ICAM-1 behaved as early markers of hepatic alteration, sTNFRI, IL-1Ra and ICAM-1 of renal disfunction and these and IL-6 of lung injury.