Leukocyte mitochondrial membrane potential in type 1 diabetes families

Background: Proper cellular function requires the maintenance of mitochondrial membrane potential (MMP) sustained by the electron transport chain. Mitochondrial dysfunction is believed to play a role in the development of diabetes and diabetic complications possibly because of the active generation of free radicals. Since MMP can be investigated in clinical settings using fluorescent probes and living whole blood cells, mitochondrial membrane alterations have been observed in some chronic disorders. Materials and Methods: We have used the mitochondrial indicator 5,5’,6,6’-tetra chloro-1,1’,3,3’-tetraethylbenzimidazolyl-carbocyanine iodide (JC-1) in conjunction with flow cytometry to measure the MMP in peripheral blood granulocytes from type 1 diabetes (T1D) families (diabetic probands and non-diabetic siblings). The intracellular ROS levels and the respiratory burst activity were also measured. Results: Leukocyte MMP was elevated in 20 T1D patients and their 20 non-diabetic siblings compared with 25 healthy subjects without family history of T1D. Fasting plasma glucose was the only correlate of MMP. Conclusions: The flow cytometric finding of mitochondrial hyperpolarisation in circulating leukocytes suggests a functional synchronization across the mitochondrial network in T1D family members, even without frank diabetes. The functional implications of mitochondrial hyperpolarisation (probably different among different cells) will require extensive investigation.