TEMPORAL CHARACTERISATION OF RENAL IMMUNOPHENOTYPE WITH MITOCHONDRIAL KINETIC PROFILE IN A PRECLINICAL MODEL OF DIABETIC KIDNEY DISEASE
Ms Inez Trambas1, Ms Adrienne Laskowski1, Ms Amalia Khayyira1, Dr Arpeeta Sharma1, Professor Trent Woodruff2, Associate Professor Melinda Coughlan1, Dr Sih Min Tan1
1Monash University, Melbourne, Australia, 2University of Queensland, Brisbane, Australia
Aim: To map renal immunophenotypic and mitochondrial bioenergetic adaptations to diabetic kidney disease (DKD) in a time-course model of diabetes.
Background: Mitochondria are the gatekeepers between metabolism, immunity, and inflammation. While both mitochondrial dysfunction and inflammation have been implicated in DKD, the link between the two remains poorly understood. Previously, we have shown that both mitochondrial functional changes and macrophage infiltration into the kidney occur early in disease in preclinical DKD models. However, the interdependencies between diverse immune cells in the kidney and mitochondrial metabolism during the progression of DKD has never been investigated.
Methods: Experimental diabetes was induced in 6-week-old C57BL/6J mice by five daily injections of streptozotocin (STZ; 55mg/kg) and followed for 10 and 20 weeks. 24-hour urine was collected for albuminuria. Mitochondria were isolated from renal cortices and oxygen consumption rate (OCR) was determined with Seahorse XF Analyzer. Comprehensive immunophenotyping was performed on renal and splenic cells using spectral flow cytometry.
Results: As expected, diabetes was associated with a progressive increase in albuminuria, water intake, urine output, left kidney-to-body-weight ratio, plasma glucose and HbA1c over the time-course when compared to nondiabetic cohorts (P<0.05). Diabetes was associated with higher total and uncoupled oxygen consumption in renal mitochondria at 10 and 20 weeks of diabetes. Interestingly, while we observed an overall reduction in total T cells in the kidney and spleen at 10 weeks of diabetes, the proportion of anti-inflammatory CD25+FoxP3+ T regulatory cells (Tregs) was increased.
Conclusions: While the link between mitochondrial dysfunction and immunity in DKD remains unclear, this study provides an overview of changes to immune cell populations and mitochondrial bioenergetics in the progression of DKD.
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