ABSTRACT
Celiac disease (CD) is a gluten-responsive, chronic inflammatory enteropathy. IL-1 cytokine family members IL-1ß and IL-18 have been associated with the inflammatory conditions in CD patients. However, the mechanisms of IL-1 molecule activation in CD have not yet been elucidated. We show in this study that peripheral blood mononuclear cells (PBMC) and monocytes from celiac patients responded to pepsin digest of wheat gliadin fraction (PDWGF) by a robust secretion of IL-1ß and IL-1α and a slightly elevated production of IL-18. The analysis of the upstream mechanisms underlying PDWGF-induced IL-1ß production in celiac PBMC show that PDWGF-induced de novo pro-IL-1ß synthesis, followed by a caspase-1 dependent processing and the secretion of mature IL-1ß. This was promoted by K+ efflux and oxidative stress, and was independent of P2X7 receptor signaling. The PDWGF-induced IL-1ß release was dependent on Nod-like receptor family containing pyrin domain 3 (NLRP3) and apoptosis-associated speck like protein (ASC) as shown by stimulation of bone marrow derived dendritic cells (BMDC) from NLRP3(-/-) and ASC(-/-) knockout mice. Moreover, treatment of human PBMC as well as MyD88(-/-) and Toll-interleukin-1 receptor domain-containing adaptor-inducing interferon-ß (TRIF)(-/-) BMDC illustrated that prior to the activation of caspase-1, the PDWGF-triggered signal constitutes the activation of the MyD88/TRIF/MAPK/NF-κB pathway. Moreover, our results indicate that the combined action of TLR2 and TLR4 may be required for optimal induction of IL-1ß in response to PDWGF. Thus, innate immune pathways, such as TLR2/4/MyD88/TRIF/MAPK/NF-κB and an NLRP3 inflammasome activation are involved in wheat proteins signaling and may play an important role in the pathogenesis of CD.
Subject(s)
Carrier Proteins/immunology , Gliadin/immunology , Inflammasomes/drug effects , Interleukin-1beta/immunology , Leukocytes, Mononuclear/drug effects , Peptide Fragments/pharmacology , Adaptor Proteins, Vesicular Transport/genetics , Adaptor Proteins, Vesicular Transport/immunology , Adult , Animals , Carrier Proteins/genetics , Celiac Disease , Female , Gene Expression Regulation/drug effects , Gene Expression Regulation/immunology , Gliadin/chemistry , Humans , Inflammasomes/genetics , Inflammasomes/immunology , Interleukin-1beta/genetics , Leukocytes, Mononuclear/immunology , Leukocytes, Mononuclear/pathology , Male , Mice , Mice, Knockout , Middle Aged , Mitogen-Activated Protein Kinases/genetics , Mitogen-Activated Protein Kinases/immunology , Myeloid Differentiation Factor 88/genetics , Myeloid Differentiation Factor 88/immunology , NLR Family, Pyrin Domain-Containing 3 Protein , Pepsin A , Primary Cell Culture , Signal Transduction/drug effects , Signal Transduction/genetics , Signal Transduction/immunology , Toll-Like Receptor 2/genetics , Toll-Like Receptor 2/immunology , Toll-Like Receptor 4/genetics , Toll-Like Receptor 4/immunologyABSTRACT
BACKGROUND & AIMS: Copolymers of hydroxyethyl methacrylate and styrene sulfonate complex with isolated gliadin (the toxic fraction of gluten) and prevent damage to the intestinal barrier in HLA-HCD4/DQ8 mice. We studied the activity toward gluten and hordein digestion and biologic effects of poly(hydroxyethyl methacrylate-co-styrene sulfonate (P(HEMA-co-SS)). We also investigated the effect of gliadin complex formation in intestinal biopsy specimens from patients with celiac disease. METHODS: We studied the ability of P(HEMA-co-SS) to reduce digestion of wheat gluten and barley hordein into immunotoxic peptides using liquid chromatography-mass spectrometry. The biodistribution and pharmacokinetic profile of orally administered P(HEMA-co-SS) was established in rodents using tritium-labeled polymer. We assessed the capacity of P(HEMA-co-SS) to prevent the immunologic and intestinal effects induced by a gluten-food mixture in gluten-sensitized HLA-HCD4/DQ8 mice after short-term and long-term administration. We measured the effects of gliadin complex formation on cytokine release ex vivo using intestinal biopsy specimens from patients with celiac disease. RESULTS: P(HEMA-co-SS) reduced digestion of wheat gluten and barley hordein in vitro, thereby decreasing formation of toxic peptides associated with celiac disease. After oral administration to rodents, P(HEMA-co-SS) was predominantly excreted in feces, even in the presence of low-grade mucosal inflammation and increased intestinal permeability. In gluten-sensitized mice, P(HEMA-co-SS) reduced paracellular permeability, normalized anti-gliadin immunoglobulin A in intestinal washes, and modulated the systemic immune response to gluten in a food mixture. Furthermore, incubation of P(HEMA-co-SS) with mucosal biopsy specimens from patients with celiac disease showed that secretion of tumor necrosis factor-α was reduced in the presence of partially digested gliadin. CONCLUSIONS: The copolymer P(HEMA-co-SS) reduced digestion of wheat gluten and barley hordein and attenuated the immune response to gluten in a food mixture in rodents. It might be developed to prevent or reduce gluten-induced disorders in humans.
