Fig. 1: Disruption of the crinophagic pathway in pancreatic β cells leads to suppression of autoimmune diabetes development in NOD mice.

a Immunogold electron microscopy depicting vesicles differentially labeled for insulin (18 nm, indicated by red arrow) and LAMP1 (12 nm, indicated by blue arrow) in a β-cell from 6-week-old male NOD mice. Also shown are three individual granules, some containing both insulin and LAMP1, while others contain only insulin or LAMP1. Data are representative of two independent experiments. b Immunogold electron microscopy depicting a representative granule containing both insulin B-chain (18 nm, indicated by red arrow) and LAMP1 (12 nm, indicated by blue arrow) from 6-week-old male NOD mice. Data are representative of two independent experiments. c Immunogold electron microscopy depicting two representative granules containing both insulin (6 nm, indicated by red arrow) and LAMP1 (12 nm, indicated by blue arrow) from 4-week-old female NOD mice. Data are representative of two independent experiments. d Representative electron microscopy images showing β cells from 6-week-old male NOD mice post-treatment with chloroquine or PBS control (upper). The data show randomly selected regions from a β cell. In each region, crinophagic granules, which have the morphology of multivesicular bodies containing secretory granules, are denoted by purple arrows. The violin plots (lower) summarize the numbers of the crinophagic granules per β cell in 6-week-old male or 4-week-old female NOD mice. Data are from two independent experiments. Each symbol represents individual β cells. ****P < 0.0001; Mann–Whitney test, two-tailed. e Schematic (upper) depicting an antigen presentation assay designed for testing the presentation of the insulin epitope G20 or E21 contained in crinosome or DCG subcellular fractions isolated from islets of NOD mice given PBS or chloroquine. Created in BioRender. Wan, X. (2024) BioRender.com/w12p880. The bar graphs (lower) summarize results (mean ± s.e.m) from three or four independent experiments in 6-week-old male or 4-week-old female NOD mice. Each symbol represents one independent experiment including 2–5 mice pooled together (for experiment for males: n = 15 in total; for experiment for females: n = 16 in total). ns, not significant; ****P < 0.0001; one-way ANOVA analysis. f Diabetes development of female NOD mice that were left untreated (n = 12) or treated with PBS (n = 17) or chloroquine (n = 30). The median age of diabetes onset for each group is indicated. Diabetes incidence was determined by three independent monitoring experiments. ns not significant; **P = 0.0055; *P = 0.0262; Log-rank (Mantel–Cox) test.