Celiac Disease Defined by Over-Sensitivity to Gliadin Activation and Superior Antigen Presentation of Dendritic Cells

Abstract

The autoimmune condition, Celiac Disease (CeD), displays broad clinical symptoms due to gluten exposure. Its genetic association with DQ variants in the human leukocyte antigen (HLA) system has been recognised. Monocyte-derived mature dendritic cells (MoDCs) present gluten peptides through HLA-DQ and co-stimulatory molecules to T lymphocytes, eliciting a cytokine-rich microenvironment. Having access to CeD associated families prevalent in the Czech Republic, this study utilised an in vitro model to investigate their differential monocyte profile. The higher monocyte yields isolated from PBMCs of CeD patients versus control individuals also reflected the greater proportion of dendritic cells derived from these sources following lipopolysaccharide (LPS)/ peptic-tryptic-gliadin (PTG) fragment stimulation. Cell surface markers of CeD monocytes and MoDCs were subsequently profiled. This foremost study identified a novel bio-profile characterised by elevated CD64 and reduced CD33 levels, unique to CD14++ monocytes of CeD patients. Normalisation to LPS stimulation revealed the increased sensitivity of CeD-MoDCs to PTG, as shown by CD86 and HLA-DQ flow cytometric readouts. Enhanced CD86 and HLA-DQ expression in CeD-MoDCs were revealed by confocal microscopy. Analysis highlighted their dominance at the CeD-MoDC membrane in comparison to controls, reflective of superior antigen presentation ability. In conclusion, this investigative study deciphered the monocytes and MoDCs of CeD patients with the identification of a novel bio-profile marker of potential diagnostic value for clinical interpretation. Herein, the characterisation of CD86 and HLA-DQ as activators to stimulants, along with robust membrane assembly reflective of efficient antigen presentation, offers CeD targeted therapeutic avenues worth further exploration.

Enhanced Extracellular Transfer of HLA-DQ Activates CD3+ Lymphocytes towards Compromised Treg Induction in Celiac Disease

“…CD86 upregulation in CeD-MoDCs has been previously reported [ 10 ]. This potent T cell co-stimulatory molecule, along with HLA class-I and -II complexes, have been found in MoDC exosomes within preformed microdomains, prompting an examination of their immunostimulatory capacities [ 22 ].…”

“…MHC-TCR engagement binds the MoDC to the T -lymphocyte in the act of antigen presentation. This hallmark mechanism of the adaptive immunity has been exploited through the cultivation and differentiation of CeD and CTL monocytes into MoDCs, as previously reported [ 10 ]. The co-cultivation of such MoDCs with T cells enabled the monitoring of viability and intercellular interaction ( Figure 1 A).…”

“…Collectively, 40% of the genetic risk for CeD development is conferred by HLA genes [ 39 ]. More specifically, CeD is strongly associated with HLA-DQ [ 40 ], particularly in patients from the Czech Republic [ 10 ]. Given that monocytes were isolated from the blood of this CeD patient population and the recognized role of exosomes as MHC/HLA vehicles, this foremost study deciphered HLA-DQA1 and HLA-DQB1 for exosome targeting/localization sequences.…”

“…Written informed consent was obtained from all individuals involved in this study with approval from the Ethics Committee of the Institute for Clinical and Experimental Medicine and Thomayer Hospital, Prague, Czech Republic (approval number: G-18–23). A total of 11 participants ( n = 11) were enrolled, as previously reported [ 10 ], and categorized as follows: Gluten-free diet (GFD)-treated CeD patients (CeD: n = 4); normal controls with no known auto-immune disease, inflammation or malignancy (CTL: n = 7). All subjects were Caucasians of European ancestry.…”

“…Gluten is incompletely cleaved into short peptides by gastric, pancreatic and brush border enzymes that are presented in proximity to the lamina propria of the small intestine, eliciting the basis of the CeD auto-immune response [ 4 , 5 , 6 , 7 ]. Affecting 1–2% of Caucasian populations, CeD is prompted by familial inheritance predisposition to auto-immunity [ 8 ] and selective genotypic status involving human leukocyte antigen (HLA) class-II DQ2 (DQA1 *05:01/DQB1 *02:01) and DQ8 (DQA1 *03:01/DQB1 *03:02) alleles [ 9 , 10 , 11 , 12 ].…”