Islet amyloid disrupts MHC class II antigen presentation and delays autoimmune diabetes in NOD mice
Bibliographic record
Abstract
AIMS/HYPOTHESIS: Islet amyloid contributes to beta cell failure in type 2 diabetes through several mechanisms, one being the potent induction of local islet inflammation through activating inflammatory pathways in islet macrophages. As islet amyloid has recently been reported in pancreases of people with type 1 diabetes, and islet macrophages are thought to play a role in the pathogenesis of type 1 diabetes, we sought to understand the impact of islet amyloid on islet macrophages and beta cell autoimmunity. METHODS: We performed an unbiased phenotypic investigation of islet macrophages in the early stage of islet amyloid formation using single-cell RNA-seq of resident islet macrophages in mice with and without the amyloidogenic form of human islet amyloid polypeptide (hIAPP). The role of islet amyloid in autoimmune diabetes and antigen presentation was assessed in hIAPP-expressing NOD mice and in antigen-presenting cells ex vivo. RESULTS: MHC class II (MHCII) antigen presentation genes were strongly downregulated in islet macrophages during islet amyloid formation. NOD mice expressing an hIAPP transgene had delayed diabetes relative to littermate controls (median onset 30.3 vs 19.5 weeks, p=0.016). Likewise, physiological expression of hIAPP by genetic knockin also delayed diabetes in NOD mice relative to littermate controls (median onset 28.2 vs 18.0 weeks, p=0.049), corresponding with decreased markers of antigen presentation and activation, as well as decreased immune cell infiltration in islets. Adoptive transfer studies showed that systemic autoimmune function remained intact and beta cells from hIAPP transgenic mice did not evade immune recognition by diabetogenic T cells, collectively indicating the protection from diabetes was mediated by decreased antigen presentation in the pancreas. Consistent with this, incubation of dendritic cells with islet amyloid polypeptide (IAPP) aggregates decreased MHCII surface expression and diminished antigen-specific T cell activation through a phagocytosis-dependent mechanism. CONCLUSIONS/INTERPRETATION: Collectively, our data reveal a novel role for IAPP aggregates in decreasing MHCII antigen presentation and show that despite the well-established proinflammatory response of macrophages to IAPP aggregates, the uptake of IAPP aggregates during early amyloid formation also disrupts beta cell autoimmunity and delays diabetes in NOD mice.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".