Biology subjects

de Boer, J. H.

Publications and source records attributed to de Boer, J. H..

5 recordsLinked to original sources

bioRxiv2023

A cis-regulatory element regulates ERAP2 expression through autoimmune disease risk SNPs

Single nucleotide polymorphisms (SNP) near the ERAP2 gene are associated with autoimmune conditions such as Crohns disease, and birdshot chorioretinopathy, as well as protection against lethal infections, including the Black Death. Due to high linkage disequilibrium (LD), a great number of trait-associated SNPs are correlated with ERAP2 expression, however their functional mechanisms remain unidentified. We used genome editing and functional genomics to identify causal variants that remain obscured by LD. We demonstrate by reciprocal allelic replacement that ERAP2 expression is directly controlled by the genotype of splice region SNP rs2248374. However, we demonstrate that autoimmune disease-risk SNPs located near the downstream LNPEP gene promoter are independently associated with ERAP2 expression. Allele-specific conformation capture assays revealed long-range chromatin contacts between the LNPEP promoter region and the ERAP2 promoter and showed that interactions were stronger in patients carrying the alleles that increase susceptibility to autoimmune diseases. Replacing the disease-associated SNPs in the LNPEP promoter by reference sequences lowered ERAP2 expression. These findings show that clustered GWAS signals associated with diverse autoimmune conditions and lethal infections act in concert to control ERAP2 expression and that disease-associated variants can convert a gene promoter region into a potent enhancer of a distal gene.

genomics↗

bioRxiv2021

Whole transcriptome-sequencing and network analysis of CD1c+ human dendritic cells identifies cytokine-secreting subsets linked to type I IFN-negative autoimmunity to the eye

BackgroundType I interferons (IFNs) promote the expansion of subsets of CD1c+ conventional dendritic cells (CD1c+ DCs), but the molecular basis of CD1c+ DCs involvement in conditions not associated without elevated type I IFNs remains unclear. MethodsWe analyzed CD1c+ DCs from two cohorts of non-infectious uveitis patients and healthy donors using RNA-sequencing followed by high-dimensional flow cytometry to characterize the CD1c+ DC populations. ResultsWe report that the CD1c+ DCs pool from patients with non-infectious uveitis is skewed towards a gene module with the chemokine receptor CX3CR1 as the key hub gene. We confirmed these results in an independent case-control cohort and show that the disease-associated gene module is not mediated by type I IFNs. An analysis of peripheral blood using flow cytometry revealed that CX3CR1+ DC3s were diminished, whereas CX3CR1-DC3s were not. Stimulated CX3CR1+ DC3s secrete high levels of inflammatory cytokines, including TNF-alpha, and CX3CR1+ DC3-like cells can be detected in inflamed eyes of patients. ConclusionsThese results show that CX3CR1+ DC3s are implicated in non-infectious uveitis and can secrete proinflammatory mediators implicated in its pathophysiology. FundingThe presented work is supported by UitZicht (project number #2014-4, #2019-10, an #2021-4). The funders had no role in the design, execution, interpretation, or writing of the study.

immunology↗

bioRxiv2020

ERAP2 facilitates a subpeptidome of Birdshot Uveitis-associated HLA-A29

Birdshot Uveitis (BU) is a blinding inflammatory eye condition that only affects HLA-A29-positive individuals. Genetic association studies linked ERAP2 with BU, an aminopeptidase which trims peptides before their presentation by HLA class I at the cell surface, which suggests that ERAP2-dependent peptide presentation by HLA-A29 drives the pathogenesis of BU. However, it remains poorly understood whether the effects of ERAP2 on the HLA-A29 peptidome are distinct from its effect on other HLA allotypes. To address this, we focused on the effects of ERAP2 on the immunopeptidome in patient-derived antigen presenting cells. Using complementary HLA-A29-based and pan-class I immunopurifications, isotope-labelled naturally processed and presented HLA-bound peptides were sequenced by mass spectrometry. We show that the effects of ERAP2 on the N-terminus of ligands of HLA-A29 are shared across endogenous HLA allotypes, but discover and replicate that one peptide motif generated in the presence of ERAP2 is specifically bound by HLA-A29. This motif can be found in the amino acid sequence of putative autoantigens. We further show evidence for internal sequence specificity for ERAP2 imprinted in the immunopeptidome. These results reveal that ERAP2 can generate an HLA-A29-specific antigen repertoire, which supports that antigen presentation is a key disease pathway in BU.

immunology↗

bioRxiv2018

Functionally distinct ERAP1 and ERAP2 are a hallmark of HLA-A29-(Birdshot) Uveitis.

Birdshot Uveitis (Birdshot) is a rare eye condition that affects HLA-A29-positive individuals and could be considered a prototypic member of the recently proposed \"MHC-I-opathy\" family. Genetic studies have pinpointed the ERAP1 and ERAP2 genes as shared associations across MHC-I-opathies, which suggests ERAP dysfunction may be a root cause for MHC-I-opathies. We mapped the ERAP1 and ERAP2 haplotypes in 84 Dutch cases and 890 controls. We identified association at variant rs10044354, which mediated a marked increase in ERAP2 expression. We also identified and cloned an independently associated ERAP1 haplotype (tagged by rs2287987) present in more than half of the cases; this ERAP1 haplotype is also the primary risk and protective haplotype for other MHC-I-opathies. We show that the risk ERAP1 haplotype conferred significantly altered expression of ERAP1 isoforms in transcriptomic data (n=360), resulting in lowered protein expression and distinct enzymatic activity. Both the association for rs10044354 (meta-analysis: OR[95% CI]=2.07[1.58-2.71], p=1.24 x 10(-7)) and rs2287987 (OR[95% CI]: =2.01 [1.51-2.67], p=1.41 x 10(-6)) replicated and showed consistent direction of effect in an independent Spanish cohort of 46 cases and 2,103 controls. In both cohorts, the combined rs2287987-rs10044354 haplotype associated with Birdshot more strongly than either SNP alone (meta-analysis: p=3.9 x 10(-9)). Finally, we observed that ERAP2 protein expression is dependent on the ERAP1 background across three European populations (n=3,353). In conclusion, a functionally distinct combination of ERAP1 and ERAP2 are a hallmark of Birdshot and provide rationale for strategies designed to correct ERAP function for treatment of Birdshot and MHC-I-opathies more broadly.

genetics↗

bioRxiv2017

An Amino Acid Motif In HLA-DRB1 Distinguishes Patients With Uveitis In Juvenile Idiopathic Arthritis

ObjectivesUveitis is a visually-debilitating disorder that affects up to 30% of children with the most common forms of juvenile idiopathic arthritis (JIA). The disease mechanisms predisposing only a subgroup of children to uveitis are unknown. To identify genetic susceptibility loci for uveitis in JIA, we conducted a genome-wide association study totalling 522 JIA cases.\n\nMethodsTwo cohorts of JIA patients with ophthalmological follow-up were separately genotyped and then imputed using a genome-wide imputation reference panel, and an HLA-specific reference panel used for imputing amino acids and HLA types in the major histocompatibility complex (MHC). After imputation, we performed genome-wide and MHC-specific analyses. We used a reverse immunology approach to model antigen presentation at 13 common HLA-DRB1 allotypes.\n\nResultsWe identified the amino acid serine at position 11 (serine-11) in HLA-DRB1 as associated to increased risk of uveitis (OR = 2.60, p = 5.43 x 10-10). We found the serine-11 signal to be specific to females (pfemales = 7.61 x 10-10, pmales = 0.18). Serine-11 resides in the YST-motif in the peptide binding groove of the HLA-DRB1 protein; all three amino acids are in perfect linkage disequilibrium and show identical association to disease. Quantitative prediction of binding affinity revealed that discernable peptide-binding preferences distinguish HLA-DRB1 allotypes with the YST-motif.\n\nConclusionOur findings highlight a genetically distinct, sexually-dimorphic feature of JIA-uveitis compared to JIA without uveitis in HLA-DRB1. The association indicates the potential involvement for antigen presentation by HLA-DRB1 in the development of uveitis in JIA.

genetics↗