Den Hollander, A. I. | Search bioRxiv

bioRxiv2020

The metabolite receptor SUCNR1 in oxidative stress-induced age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of vision impairment in elderly people. AMD is a multifactorial disease which is characterised by complex interactions between metabolic and environmental factors as well as multiple genetic susceptibility factors. The exact mechanism of the most prominent environmental factors, age and smoking, in combination with genetic susceptibility factors is little studied. Here, we set out to study the influence of age, smoking induced oxidative stress and the role of succinate receptor 1 (SUCNR1) in AMD development in mice. Sucnr1 wild-type (WT), heterozygous (HT) and knock-out (KO) mice were exposed to smoking related oxidative stress by the addition of hydroquinone (HQ), the most abundant oxidant in cigarette smoke, to the drinking water of the mice. Using immunohistochemical staining, accumulation of oxidized LDL (oxLDL) in the mouse retina was assessed at 40 and 48 weeks of age. At 40 weeks of age, a significant increase in oxLDL in the Sucnr1 KO mice treated with HQ was observed when compared to the WT and HT mice treated with HQ (p<0.01). However, at 48 weeks, no significant difference was observed between any of the groups. A second experiment analyzing the mice at 40 weeks of age was unable to confirm the observed results of the first experiment. We identified oxLDL accumulations in Sucnr1 KO retinas exposed to HQ, but were unable to repeat this finding. Therefore, under the present conditions, the Sucnr1 KO mouse model is not a suitable model to study AMD development.

biochemistry↗

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↗