Oxidative Stress and Cardiovascular Risk in Type 1 Diabetes Mellitus: Insights From the DCCT/EDIC Study

Background

Hyperglycemia leading to increased oxidative stress is implicated in the increased risk for the development of macrovascular and microvascular complications in patients with type 1 diabetes mellitus.

Methods and Results

A random subcohort of 349 participants was selected from the DCCT / EDIC (Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications) cohort. This included 320 controls and 29 cardiovascular disease cases that were augmented with 98 additional known cases to yield a case cohort of 447 participants (320 controls, 127 cases). Biosamples from DCCT baseline, year 1, and closeout of DCCT , and 1 to 2 years post‐ DCCT ( EDIC years 1 and 2) were measured for markers of oxidative stress, including plasma myeloperoxidase, paraoxonase activity, urinary F 2α isoprostanes, and its metabolite, 2,3 dinor‐8 iso prostaglandin F 2α . Following adjustment for glycated hemoblobin and weighting the observations inversely proportional to the sampling selection probabilities, higher paraoxonase activity, reflective of antioxidant activity, and 2,3 dinor‐8 iso prostaglandin F 2α , an oxidative marker, were significantly associated with lower risk of cardiovascular disease (−4.5% risk for 10% higher paraoxonase, P <0.003; −5.3% risk for 10% higher 2,3 dinor‐8 iso prostaglandin F 2α , P =0.0092). In contrast, the oxidative markers myeloperoxidase and F 2α isoprostanes were not significantly associated with cardiovascular disease after adjustment for glycated hemoblobin. There were no significant differences between DCCT intensive and conventional treatment groups in the change in all biomarkers across time segments.

Conclusions

Heightened antioxidant activity (rather than diminished oxidative stress markers) is associated with lower cardiovascular disease risk in type 1 diabetes mellitus, but these biomarkers did not change over time with intensification of glycemic control.

Clinical Trial Registration

URL : https://www.clinicaltrials.gov . Unique identifiers: NCT 00360815 and NCT 00360893.

Expression of interleukin-5 by human bone marrow microvascular endothelial cells: implications for the regulation of eosinophilopoiesis in vivo

We have shown that bone marrow microvascular endothelial cells (BMEC) support growth and differentiation of haemopoietic progenitors in vitro by elaboration of haemopoietic cytokines. Since generation of eosinophils can be observed in these coculture experiments, and BMEC do not produce interleukin (IL)-3, we evaluated BMEC for expression of IL-5, a specific growth factor for the eosinophilic lineage. Using RT-PCR, IL-5 mRNA was expressed by BMEC after stimulation (12 h) with lipopolysaccharide (LPS), IL-1, IL-2 and phorbol myristate acetate (PMA), but not by resting BMEC, after stimulation with TNF-alpha or interferon (IFN)-gamma. Moreover, IFN-gamma suppressed expression of IL-5 in response to LPS and IL-2. The identity of the PCR products was confirmed by restriction enzyme digestion, which resulted in fragments of the predicted size. T lymphocytes were not present in the endothelial cultures as demonstrated by absence of CD2 mRNA. Using a sensitive (1 pg/ml) ELISA assay. IL-5 was detected after 48 h incubation of BMEC with IL-2 (4.1 pg/10(6) cells) or with a combination of LPS and IL-2 (4.8 pg). However, the number of eosinophils generated after 4 weeks coculture of CD34+ haemopoietic cells with BMEC was not increased by addition of IL-2. RT-PCR revealed that BMEC in coculture with haemopoietic cells expressed IL-5 even without addition of exogenous cytokines or stimulating agents. In conclusion, expression of IL-5 by BMEC can be stimulated by cytokines (IL-1, IL-2), LPS, PMA, and coculture with proliferating haemopoietic cells. Thus, BMEC may support proliferation and differentiation of eosinophils in the bone marrow. IFN-gamma represents a cytokine with an inhibitory effect on IL-5 expression by BMEC. In addition, eosinophilia in response to circulating IL-2 or bacterial products (LPS) in vivo may be partially mediated by BMEC or vascular endothelium.