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- Strollo, Rocky, et al.
(author)
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Autoantibody and T cell responses to oxidative post-translationally modified insulin neoantigenic peptides in type 1 diabetes
- 2023
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In: Diabetologia. - : Springer. - 0012-186X .- 1432-0428. ; 66:1, s. 132-146
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Journal article (peer-reviewed)abstract
- Aims/hypothesis Antibodies specific to oxidative post-translational modifications (oxPTM) of insulin (oxPTM-INS) are present in most individuals with type 1 diabetes, even before the clinical onset. However, the antigenic determinants of such response are still unknown. In this study, we investigated the antibody response to oxPTM-INS neoepitope peptides (oxPTM-INSPs) and evaluated their ability to stimulate humoral and T cell responses in type 1 diabetes. We also assessed the concordance between antibody and T cell responses to the oxPTM-INS neoantigenic peptides. Methods oxPTM-INS was generated by exposing insulin to various reactive oxidants. The insulin fragments resulting from oxPTM were fractionated by size-exclusion chromatography further to ELISA and LC-MS/MS analysis to identify the oxidised peptide neoepitopes. Immunogenic peptide candidates were produced and then modified in house or designed to incorporate in silico-oxidised amino acids during synthesis. Autoantibodies to the oxPTM-INSPs were tested by ELISA using sera from 63 participants with new-onset type 1 diabetes and 30 control participants. An additional 18 fresh blood samples from participants with recently diagnosed type 1 diabetes, five with established disease, and from 11 control participants were used to evaluate, in parallel, CD4(+) and CD8(+) T cell activation by oxPTM-INSPs. Results We observed antibody and T cell responses to three out of six LC-MS/MS-identified insulin peptide candidates: A:12-21 (SLYQLENYCN, native insulin peptide 3 [Nt-INSP-3]), B:11-30 (LVEALYLVCGERGFFYTPKT, Nt-INSP-4) and B:21-30 (ERGFFYTPKT, Nt-INSP-6). For Nt-INSP-4 and Nt-INSP-6, serum antibody binding was stronger in type 1 diabetes compared with healthy control participants (p <= 0.02), with oxidised forms of ERGFFYTPKT, oxPTM-INSP-6 conferring the highest antibody binding (83% binders to peptide modified in house by hydroxyl radical [(OH)-O-?] and >88% to in silico-oxidised peptide; p <= 0.001 vs control participants). Nt-INSP-4 induced the strongest T cell stimulation in type 1 diabetes compared with control participants for both CD4(+) (p<0.001) and CD8(+) (p=0.049). CD4(+) response to oxPTM-INSP-6 was also commoner in type 1 diabetes than in control participants (66.7% vs 27.3%; p=0.039). Among individuals with type 1 diabetes, the CD4(+) response to oxPTM-INSP-6 was more frequent than to Nt-INSP-6 (66.7% vs 27.8%; p=0.045). Overall, 44.4% of patients showed a concordant autoimmune response to oxPTM-INSP involving simultaneously CD4(+) and CD8(+) T cells and autoantibodies. Conclusions/interpretation Our findings support the concept that oxidative stress, and neoantigenic epitopes of insulin, may be involved in the immunopathogenesis of type 1 diabetes.
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| 2. |
- Strollo, Rocky, et al.
(author)
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Antibodies to oxidized insulin improve prediction of type 1 diabetes in children with positive standard islet autoantibodies
- 2019
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In: Diabetes/Metabolism Research Reviews. - : John Wiley & Sons. - 1520-7552 .- 1520-7560. ; 35:4
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Journal article (peer-reviewed)abstract
- BackgroundAntibodies to posttranslationally modified insulin (oxPTM‐INS‐Ab) are a novel biomarker of type 1 diabetes (T1D). Here, we evaluated whether oxPTM‐INS‐Ab can improve T1D prediction in children with positive standard islet autoantibodies (AAB).MethodsWe evaluated sensitivity, specificity, accuracy, and risk for progression to T1D associated with oxPTM‐INS‐Ab and the standard islet AAB that include insulin (IAA), GAD (GADA), and tyrosine phosphatase 2 (IA‐2A) in a cohort of islet AAB‐positive (AAB+) children from the general population (median follow‐up 8.8 years).ResultsoxPTM‐INS‐Ab was the most sensitive and specific autoantibody biomarker (74% sensitivity, 91% specificity), followed by IA‐2A (71% sensitivity, 91% specificity). GADA and IAA showed lower sensitivity (65% and 50%, respectively) and specificity (66% and 68%, respectively). Accuracy (AUC of ROC) of oxPTM‐INS‐Ab was higher than GADA and IAA (P = 0.003 and P = 0.017, respectively), and similar to IA‐2A (P = 0.896). oxPTM‐INS‐Ab and IA‐2A were more effective than IAA for detecting progr‐T1D when used as second‐line biomarker in GADA+ children. Risk for diabetes was higher (P = 0.03) among multiple AAB+ who were also oxPTM‐INS‐Ab+ compared with those who were oxPTM‐INS‐Ab–. Importantly, when replacing IAA with oxPTM‐INS‐Ab, diabetes risk increased to 100% in children with oxPTM‐INS‐Ab+ in combination with GADA+ and IA‐2A+, compared with 84.37% in those with IAA+, GADA+, and IA‐2A+ (P = 0.04).ConclusionsAntibodies to oxidized insulin (oxPTM‐INS‐Ab), compared with IAA which measure autoantibodies to native insulin, improve T1D risk assessment and prediction accuracy in AAB+ children.
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| 3. |
- Strollo, Rocky, et al.
(author)
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Antibodies to post-translationally modified insulin as a novel biomarker for prediction of type 1 diabetes in children
- 2017
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In: Diabetologia. - : SPRINGER. - 0012-186X .- 1432-0428. ; 60:8, s. 1467-1474
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Journal article (peer-reviewed)abstract
- Aims/hypothesis We have shown that autoimmunity to insulin in type 1 diabetes may result from neoepitopes induced by oxidative post-translational modifications (oxPTM). Antibodies specific to oxPTM-insulin (oxPTM-INS-Ab) are present in most newly diagnosed individuals with type 1 diabetes and are more common than autoantibodies to native insulin. In this study, we investigated whether oxPTM-INS-Ab are present before clinical onset of type 1 diabetes, and evaluated the ability of oxPTM-INS-Ab to identify children progressing to type 1 diabetes. Methods We used serum samples collected longitudinally from the All Babies in Southeast Sweden (ABIS) cohort tested for the gold standard islet autoantibodies to insulin (IAA), GAD (GADA), tyrosine phosphatase 2 (IA-2A) and zinc transporter 8 (ZnT8A). We studied 23 children who progressed to type 1 diabetes (progr-T1D) and 63 children who did not progress to type 1 diabetes (NP) after a median follow-up of 10.8 years (interquartile range 7.7-12.8). Of the latter group, 32 were positive for one or more islet autoantibodies (NP-AAB(+)). oxPTM-INS-Ab to insulinmodified by (OH)-O-center dot or HOCl were measured by our developed ELISA platform. Results Antibodies to at least one oxPTM-INS were present in 91.3% of progr-T1D children. oxPTM-INS-Ab co-existed with GADA, IA-2A, IAA or ZnT8A in 65.2%, 56.5%, 38.9% and 33.3% progr-T1D children, respectively. In addition, oxPTM-INS-Ab were present in 17.4%, 26.1%, 38.9% and 41.6% of progr-T1D children who were negative for GADA, IA-2A, IAA and ZnT8A, respectively. (OH)-O-center dot-INS-Ab were more common in progr-T1D children than in NP-AAB+ children (82.6% vs 19%; p amp;lt; 0.001) and allowed discrimination between progr-T1D and NP-AAB(+) children with 74% sensitivity and 91% specificity. None of the NP-AAB(-) children were positive for oxPTM-INS-Ab. Conclusions/interpretation oxPTM-INS-Ab are present before the clinical onset of type 1 diabetes and can identify children progressing to type 1 diabetes.
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