Phenotype of haptoglobin and presence of subclinical vascular disease: Population study. / Fenotipo de la haptoglobina y presencia de enfermedad vascular subclínica: estudio poblacional.

INTRODUCTION AND OBJECTIVES: Haptoglobin is a protein involved in the protection against oxidative damage caused by iron in haemoglobin. This protein is polymorphic, with 3 isomorphs prevalent in the population. The carriers of the Hp2-2 isoform have a lower antioxidant capacity and, in the population with diabetes, an increased risk of subclinical vascular disease and cardiovascular complications. The objective of this study was to evaluate whether this isomorphy is associated with an increased risk of carotid arteriosclerosis in subjects with and without diabetes, and free of cardiovascular disease. PATIENTS AND METHODS: A study was conducted in a population between 45 and 74years of age, randomly selected from the northwest area of Madrid. The participants were characterised in terms of their glycaemic status by oral glucose overload and the determination of the concentration of Hb1Ac. The haptoglobin phenotypes in all of them were determined by means of an immunoenzymatic assay, and the presence of carotid arteriosclerosis by ultrasound. RESULTS: Of the 1,256 participants included in the present analysis (mean age 61.6±6years, 41.8% males), the distribution of the isoforms of haptoglobin was as follows: Hp1-1: 13.3%, Hp1-2: 48.5%, and Hp2-2: 38.2%. In comparison with subjects Hp1-1 and Hp1-2, those with the Hp2-2 phenotype had a higher prevalence of dyslipidaemia (53.3% vs 43%; P<.0001) and arterial hypertension (39.2% vs. 32.2%, P=.012), and they more frequently received treatment with statins (31.5% vs 21.6%, P<.0001), and with antihypertensive agents (38.4% vs 30.8%, P=.006). The carriers of the Hp2-2 isoform had a higher prevalence of carotid plaques (OR: 1.35, 95%CI: 1.07-1.69, P=.011), with no differences in that prevalence as regards the glycaemic status. There were no differences in the intima-media thickness between the different phenotypes. The relationship of the Hp2-2 phenotype with the presence of plaques in the carotid was independent of age, gender, presence of risk factors (dyslipidaemia, hypertension and diabetes), the concentration of LDL-cholesterol, C-reactive protein and uric acid, blood pressure, and treatment with statins, and hypertensive drugs (OR: 1.31, 95%CI 1.01-1.70, P=.044). CONCLUSION: Subjects with the Hp2-2 phenotype of haptoglobin have a higher prevalence of carotid arteriosclerosis, which is independent of the presence of other cardiovascular risk factors and their glycaemic status.

Antibiotics in early life alter the gut microbiome and increase disease incidence in a spontaneous mouse model of autoimmune insulin-dependent diabetes.

Insulin-dependent or type 1 diabetes is a prototypic autoimmune disease whose incidence steadily increased over the past decades in industrialized countries. Recent evidence suggests the importance of the gut microbiota to explain this trend. Here, non-obese diabetic (NOD) mice that spontaneously develop autoimmune type 1 diabetes were treated with different antibiotics to explore the influence of a targeted intestinal dysbiosis in the progression of the disease. A mixture of wide spectrum antibiotics (i.e. streptomycin, colistin and ampicillin) or vancomycin alone were administered orally from the moment of conception, treating breeding pairs, and during the postnatal and adult life until the end of follow-up at 40 weeks. Diabetes incidence significantly and similarly increased in male mice following treatment with these two antibiotic regimens. In NOD females a slight yet not significant trend towards an increase in disease incidence was observed. Changes in gut microbiota composition were assessed by sequencing the V3 region of bacterial 16S rRNA genes. Administration of the antibiotic mixture resulted in near complete ablation of the gut microbiota. Vancomycin treatment led to increased Escherichia, Lactobacillus and Sutterella genera and decreased members of the Clostridiales order and Lachnospiraceae, Prevotellaceae and Rikenellaceae families, as compared to control mice. Massive elimination of IL-17-producing cells, both CD4+TCRαß+ and TCRγδ+ T cells was observed in the lamina propria of the ileum and the colon of vancomycin-treated mice. These results show that a directed even partial ablation of the gut microbiota, as induced by vancomycin, significantly increases type 1 diabetes incidence in male NOD mice thus prompting for caution in the use of antibiotics in pregnant women and newborns.

Endoplasmic reticulum targeting alters regulation of expression and antigen presentation of proinsulin.

Peptide ligands presented by MHC class I (MHC-I) molecules are produced by degradation of cytosolic and nuclear, but also endoplasmic reticulum (ER)-resident, proteins by the proteasome. However, Ag processing of ER proteins remains little characterized. Studying processing and presentation of proinsulin, which plays a pivotal role in autoimmune diabetes, we found that targeting to the ER has profound effects not only on how proinsulin is degraded, but also on regulation of its cellular levels. While proteasome inhibition inhibited degradation and presentation of cytosolic proinsulin, as expected, it reduced the abundance of ER-targeted proinsulin. This targeting and protein modifications modifying protein half-life also had profound effects on MHC-I presentation and proteolytic processing of proinsulin. Thus, presentation of stable luminal forms was inefficient but enhanced by proteasome inhibition, whereas that of unstable luminal forms and of a cytosolic form were more efficient and compromised by proteasome inhibitors. Distinct stability of peptide MHC complexes produced from cytosolic and luminal proinsulin suggests that different proteolytic activities process the two Ag forms. Thus, both structural features and subcellular targeting of Ags can have strong effects on the processing pathways engaged by MHC-I-restricted Ags, and on the efficiency and regulation of their presentation.