Adeno-Associated Viral Transfer of Glyoxalase-1 Blunts Carbonyl and Oxidative Stresses in Hearts of Type 1 Diabetic Rats

Abstract

<jats:p>Accumulation of methylglyoxal (MG) arising from downregulation of its primary degrading enzyme glyoxalase-1 (Glo1) is an underlying cause of diabetic cardiomyopathy (DC). This study investigated if expressing Glo1 in rat hearts shortly after the onset of Type 1 diabetes mellitus (T1DM) would blunt the development of DC employing the streptozotocin-induced T1DM rat model, an adeno-associated virus containing Glo1 driven by the endothelin-1 promoter (AAV2/9-Endo-Glo1), echocardiography, video edge, confocal imaging, and biochemical/histopathological assays. After eight weeks of T1DM, rats developed DC characterized by a decreased E:A ratio, fractional shortening, and ejection fraction, and increased isovolumetric relaxation time, E: e’ ratio, and circumferential and longitudinal strains. Evoked Ca2+ transients and contractile kinetics were also impaired in ventricular myocytes. Hearts from eight weeks T1DM rats had lower Glo1 and GSH levels, elevated carbonyl/oxidative stress, microvascular leakage, inflammation, and fibrosis. A single injection of AAV2/9 Endo-Glo1 (1.7 × 1012 viron particles/kg) one week after onset of T1DM, potentiated GSH, and blunted MG accumulation, carbonyl/oxidative stress, microvascular leakage, inflammation, fibrosis, and impairments in cardiac and myocyte functions that develop after eight weeks of T1DM. These new data indicate that preventing Glo1 downregulation by administering AAV2/9-Endo-Glo1 to rats one week after the onset of T1DM, blunted the DC that develops after eight weeks of diabetes by attenuating carbonyl/oxidative stresses, microvascular leakage, inflammation, and fibrosis.</jats:p>

A Link Between Methylglyoxal and Heart Failure During HIV-1 Infection

“…This conclusion is based on new findings obtained from infected Hu-mice, plasma from PLWH and autopsied cardiac tissues from deceased HIV-1 seropositive individuals with HF. MG has been previously linked to HF in other inflammatory diseases ( 60 , 68 ).…”

“…However, under inflammatory as is the case in HIV-1 infection, activated NF-κB would compete with Nrf2 to suppress Glo1 expression ( 49 , 56 , 57 ). As such, to induce expression of Glo1 under inflammatory conditions, we replaced the endogenous CMV promoter of AAV2/9 with the promoter of inflammation-induced protein endothelin-1 ( 58 , 60 ). Using this strategy, we show for the first time that increasing expression of Glo1 in hearts of HIV-infected Hu-mice decreased MG and blunted the HF seen 16 weeks post-infection, establishing that elevated MG is an underlying cause of HF in HIV-1-infected Hu-mice.…”

“…Using this strategy, we show for the first time that increasing expression of Glo1 in hearts of HIV-infected Hu-mice decreased MG and blunted the HF seen 16 weeks post-infection, establishing that elevated MG is an underlying cause of HF in HIV-1-infected Hu-mice. It should be mentioned that in this study AAV2/9-Endo-Glo1 was not given to uninfected Hu-mice as these mice have low systemic and tissue inflammation, and as such this viral construct would not express Glo1 ( 58 , 60 ).…”

“…Earlier we showed that acute exposure of vascular endothelial cells and cardiac myocytes to supraphysiologic levels of MG, perturb their intracellular Ca 2+ homeostasis and increase ROS production ( 58 , 59 ). Long-term exposure of vascular endothelial cells to MG also diminished their responses to vasodilators and expression of tight junction proteins, established causes of microvascular leakage, decreased microvascular perfusion, fibrosis, and HF ( 58 – 60 ).…”

Myofilament Glycation in Diabetes Reduces Contractility by Inhibiting Tropomyosin Movement, is Rescued by cMyBPC Domains

“…Since methylglyoxal modifications are irreversible, there are two possible approaches to correct the dysfunction: 1) decrease MG levels so these harmful adducts are not formed in the first place, or 2) identify treatments that can compensate for the dysfunction despite the continued presence of the MG modifications. Genetic approaches to depress MG levels in animal models may be beneficial, for example a recent study showing that AAV overexpression of Glo1, the enzyme that catalyzes MG, in endothelial cells improves function in a rat model of type 1 diabetes [13]. Unfortunately, approaches to reduce MG levels clinically have already failed.…”