Prevention of Diabetes in NOD Mice by Repeated Exposures to a Contact Allergen Inducing a Sub-Clinical Dermatitis

BACKGROUND: Type 1 diabetes is an autoimmune disease, while allergic contact dermatitis although immune mediated, is considered an exposure driven disease that develops due to epicutaneous contact with reactive low-molecular chemicals. The objective of the present study was to experimentally study the effect of contact allergens on the development of diabetes in NOD mice. As the link between contact allergy and diabetes is yet unexplained we also examined the effect of provocation with allergens on Natural Killer T (NKT) cells, since involvement of NKT cells could suggest an innate connection between the two diseases. METHOD: NOD mice 4 weeks of age were exposed, on the ears, to two allergens, p-phenylenediamine and 2,4-dinitrochlorobenzene respectively, to investigate the diabetes development. The mice were followed for a maximum of 32 weeks, and they were either repeatedly exposed to the allergens or only sensitized a week after arrival. The stimulation of NKT cells by the two allergens were additionally studied in C57BL/6 mice. The mice were sensitized and two weeks later provocated with the allergens. The mice were subsequently euthanized at different time points after the provocation. RESULTS: It was found that repeated application of p-phenylenediamine reduced the incidence of diabetes compared to application with water (47% vs. 93%, P = 0.004). Moreover it was shown that in C57BL/6 mice both allergens resulted in a slight increment in the quantity of NKT cells in the liver. Application of the allergens at the same time resulted in an increased number of NKT cells in the draining auricular lymph node, and the increase appeared to be somewhat allergen specific as the accumulation was stronger for p-phenylenediamine. CONCLUSION: The study showed that repeated topical application on the ears with a contact allergen could prevent the development of diabetes in NOD mice. The contact allergens gave a non-visible, sub-clinical dermatitis on the application site. The preventive effect on diabetes may be due to stimulation of peripheral NKT cells, as shown for provocation with p-phenylenediamine in the C57BL/6 mouse. This epicutaneous procedure may lead to new strategies in prevention of type 1 diabetes in humans

Impaired human hematopoiesis due to a cryptic intronic GATA1 splicing mutation

Studies of allelic variation underlying genetic blood disorders have provided important insights into human hematopoiesis. Most often, the identified pathogenic mutations result in loss-of-function or missense changes. However, assessing the pathogenicity of noncoding variants can be challenging. Here, we characterize two unrelated patients with a distinct presentation of dyserythropoietic anemia and other impairments in hematopoiesis associated with an intronic mutation in GATA1 that is 24 nucleotides upstream of the canonical splice acceptor site. Functional studies demonstrate that this single-nucleotide alteration leads to reduced canonical splicing and increased use of an alternative splice acceptor site that causes a partial intron retention event. The resultant altered GATA1 contains a five–amino acid insertion at the C-terminus of the C-terminal zinc finger and has no observable activity. Collectively, our results demonstrate how altered splicing of GATA1, which reduces levels of the normal form of this master transcription factor, can result in distinct changes in human hematopoiesis