Abstract
PurposeMAP3865c, a Mycobacterium avium subspecies paratuberculosis (MAP) cell membrane protein, has a relevant sequence homology with zinc transporter 8 (ZnT8), a beta-cell membrane protein involved in Zn++ transportation. Recently, antibodies recognizing MAP3865c epitopes have been shown to cross-react with ZnT8 in type 1 diabetes patients. The purpose of this study was to detect antibodies against MAP3865c peptides in patients with high-risk proliferative diabetic retinopathy and speculate on whether they may somehow be involved in the pathogenesis of this severe retinal disorder.MethodsBlood samples were obtained from 62 type 1 and 80 type 2 diabetes patients with high-risk proliferative diabetic retinopathy and 81 healthy controls. Antibodies against 6 highly immunogenic MAP3865c peptides were detected by indirect ELISA.ResultsType 1 diabetes patients had significantly higher rates of positive antibodies than controls. Conversely, no statistically significant differences were found between type 2 diabetes patients and controls. After categorization of type 1 diabetes patients into two groups, one with positive, the other with negative antibodies, we found that they had similar mean visual acuity (∼0.6) and identical rates of vitreous hemorrhage (28.6%). Conversely, Hashimoto's thyroiditis prevalence was 4/13 (30.7%) in the positive antibody group and 1/49 (2%) in the negative antibody group, a statistically significant difference (P = 0.016).ConclusionsThis study confirmed that type 1 diabetes patients have significantly higher rates of positive antibodies against MAP/ZnT8 peptides, but failed to find a correlation between the presence of these antibodies and the severity degree of high-risk proliferative diabetic retinopathy. The significantly higher prevalence of Hashimoto's disease among type 1 diabetes patients with positive antibodies might suggest a possible common environmental trigger for these conditions.
Highlights
Diabetes mellitus is the most common endocrine disorder in industrialized countries
According to the Early Treatment of Diabetic Retinopathy Study (ETDRS) classification, the diagnosis of high-risk Proliferative diabetic retinopathy (PDR) was made by the detection of new vessels on or within one disc diameter of the optic disc equaling or exceeding standard photograph 10A, with or without vitreous or preretinal hemorrhage; or vitreous and/or preretinal hemorrhage accompanied by new vessels either on the optic disc less than standard photograph 10A or new vessels elsewhere equaling or exceeding 1/4 disc area on ophthalmoscopic examination and fluorescein angiography [11,12]
The study group consisted of 62 Type 1 diabetes (T1D) patients and 80 Type 2 diabetes (T2D) patients, all with bilateral high-risk PDR
Summary
Diabetes mellitus is the most common endocrine disorder in industrialized countries. Two main forms are recognized [1]. Type 1 diabetes (T1D) is due to a deficiency in endogenous insulin secretion secondary to destruction of insulin-producing beta cells in the pancreas. T1D does have a peak incidence around the time of puberty, approximately 25% of cases present after 35 years of age. Type 2 diabetes (T2D) is characterized by insulin resistance with an insulin secretory defect leading to relative insulin deficiency. This group accounts for 90–95% of patients with diabetes and has a strong genetic predisposition. T2D patients are usually, but not always, older than age 40 at presentation. Obesity is a frequent finding and, in the United States, is present in 80–90% of these patients
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