Browsing by Author "Huang, Chao"

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    Dual Anti-Inflammatory and Anti-Angiogenic Action of miR-15a in Diabetic Retinopathy.
    (Elsevier, 2016-09) Wang, Qi; Navitskaya, Svetlana; Chakravarthy, Harshini; Huang, Chao; Kady, Nermin; Lydic, Todd A.; Chen, Y. Eugene; Yin, Ke-Jie; Powell, Folami Lamoke; Martin, Pamela M.; Grant, Maria B.; Busik, Julia V.; Department of Ophthalmology, IU School of Medicine
    Activation of pro-inflammatory and pro-angiogenic pathways in the retina and the bone marrow contributes to pathogenesis of diabetic retinopathy. We identified miR-15a as key regulator of both pro-inflammatory and pro-angiogenic pathways through direct binding and inhibition of the central enzyme in the sphingolipid metabolism, ASM, and the pro-angiogenic growth factor, VEGF-A. miR-15a was downregulated in diabetic retina and bone marrow cells. Over-expression of miR-15a downregulated, and inhibition of miR-15a upregulated ASM and VEGF-A expression in retinal cells. In addition to retinal effects, migration and retinal vascular repair function was impaired in miR-15a inhibitor-treated circulating angiogenic cells (CAC). Diabetic mice overexpressing miR-15a under Tie-2 promoter had normalized retinal permeability compared to wild type littermates. Importantly, miR-15a overexpression led to modulation toward nondiabetic levels, rather than complete inhibition of ASM and VEGF-A providing therapeutic effect without detrimental consequences of ASM and VEGF-A deficiencies.
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    Imbalances in Mobilization and Activation of Pro-Inflammatory and Vascular Reparative Bone Marrow-Derived Cells in Diabetic Retinopathy
    (PloS One, 2016) Chakravarthy, Harshini; Beli, Eleni; Navitskaya, Svetlana; O'Reilly, Sandra; Wang, Qi; Kady, Nermin; Huang, Chao; Grant, Maria B.; Busik, Julia V.; Department of Ophthalmology, IU School of Medicine
    Diabetic retinopathy is a sight-threatening complication of diabetes, affecting 65% of patients after 10 years of the disease. Diabetic metabolic insult leads to chronic low-grade inflammation, retinal endothelial cell loss and inadequate vascular repair. This is partly due to bone marrow (BM) pathology leading to increased activity of BM-derived pro-inflammatory monocytes and impaired function of BM-derived reparative circulating angiogenic cells (CACs). We propose that diabetes has a significant long-term effect on the nature and proportion of BM-derived cells that circulate in the blood, localize to the retina and home back to their BM niche. Using a streptozotocin mouse model of diabetic retinopathy with GFP BM-transplantation, we have demonstrated that BM-derived circulating pro-inflammatory monocytes are increased in diabetes while reparative CACs are trapped in the BM and spleen, with impaired release into circulation. Diabetes also alters activation of splenocytes and BM-derived dendritic cells in response to LPS stimulation. A majority of the BM-derived GFP cells that migrate to the retina express microglial markers, while others express endothelial, pericyte and Müller cell markers. Diabetes significantly increases infiltration of BM-derived microglia in an activated state, while reducing infiltration of BM-derived endothelial progenitor cells in the retina. Further, control CACs injected into the vitreous are very efficient at migrating back to their BM niche, whereas diabetic CACs have lost this ability, indicating that the in vivo homing efficiency of diabetic CACs is dramatically decreased. Moreover, diabetes causes a significant reduction in expression of specific integrins regulating CAC migration. Collectively, these findings indicate that BM pathology in diabetes could play a role in both increased pro-inflammatory state and inadequate vascular repair contributing to diabetic retinopathy.
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    Increase in acid sphingomyelinase level in human retinal endothelial cells and CD34+ circulating angiogenic cells isolated from diabetic individuals is associated with dysfunctional retinal vasculature and vascular repair process in diabetes
    (Elsevier, 2017-05) Kady, Nermin; Yan, Yuanqing; Salazar, Tatiana; Wang, Qi; Chakravarthy, Harshini; Huang, Chao; Beli, Eleni; Navitskaya, Svetlana; Grant, Maria; Busik, Julia; Ophthalmology, School of Medicine
    BACKGROUND: Diabetic retinopathy is a microvascular disease that results from retinal vascular degeneration and defective repair due to diabetes-induced endothelial progenitor dysfunction. OBJECTIVE: Understanding key molecular factors involved in vascular degeneration and repair is paramount for developing effective diabetic retinopathy treatment strategies. We propose that diabetes-induced activation of acid sphingomyelinase (ASM) plays essential role in retinal endothelial and CD34+ circulating angiogenic cell (CAC) dysfunction in diabetes. METHODS: Human retinal endothelial cells (HRECs) isolated from control and diabetic donor tissue and human CD34+ CACs from control and diabetic patients were used in this study. ASM messenger RNA and protein expression were assessed by quantitative polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. To evaluate the effect of diabetes-induced ASM on HRECs and CD34+ CACs function, tube formation, CAC incorporation into endothelial tubes, and diurnal release of CD34+ CACs in diabetic individuals were determined. RESULTS: ASM expression level was significantly increased in HRECs isolated from diabetic compared with control donor tissue, as well as CD34+ CACs and plasma of diabetic patients. A significant decrease in tube area was observed in HRECs from diabetic donors compared with control HRECs. The tube formation deficiency was associated with increased expression of ASM in diabetic HRECs. Moreover, diabetic CD34+ CACs with high ASM showed defective incorporation into endothelial tubes. Diurnal release of CD34+ CACs was disrupted with the rhythmicity lost in diabetic patients. CONCLUSION: Collectively, these findings support that diabetes-induced ASM upregulation has a marked detrimental effect on both retinal endothelial cells and CACs.
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    Role of Acid Sphingomyelinase in Shifting the Balance Between Proinflammatory and Reparative Bone Marrow Cells in Diabetic Retinopathy
    (Wiley, 2016-04) Chakravarthy, Harshini; Navitskaya, Svetlana; O'reilly, Sandra; Gallimore, Jacob; Mize, Hannah; Beli, Eleni; Wang, Qi; Kady, Nermin; Huang, Chao; Blanchard, Gary J.; Grant, Maria B.; Busika, Julia V.; Ophthalmology, School of Medicine
    The metabolic insults associated with diabetes lead to low-grade chronic inflammation, retinal endothelial cell damage, and inadequate vascular repair. This is partly due to the increased activation of bone marrow (BM)-derived proinflammatory monocytes infiltrating the retina, and the compromised function of BM-derived reparative circulating angiogenic cells (CACs), which home to sites of endothelial injury and foster vascular repair. We now propose that a metabolic link leading to activated monocytes and dysfunctional CACs in diabetes involves upregulation of a central enzyme of sphingolipid signaling, acid sphingomyelinase (ASM). Selective inhibition of ASM in the BM prevented diabetes-induced activation of BM-derived microglia-like cells and normalized proinflammatory cytokine levels in the retina. ASM upregulation in diabetic CACs caused accumulation of ceramide on their cell membrane, thereby reducing membrane fluidity and impairing CAC migration. Replacing sphingomyelin with ceramide in synthetic membrane vesicles caused a similar decrease in membrane fluidity. Inhibition of ASM in diabetic CACs improved membrane fluidity and homing of these cells to damaged retinal vessels. Collectively, these findings indicate that selective modulation of sphingolipid metabolism in BM-derived cell populations in diabetes normalizes the reparative/proinflammatory cell balance and can be explored as a novel therapeutic strategy for treating diabetic retinopathy.
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    Specific mesoderm subset derived from human pluripotent stem cells ameliorates microvascular pathology in type 2 diabetic mice
    (American Association for the Advancement of Science, 2022) Gil, Chang-Hyun; Chakraborty, Dibyendu; Vieira, Cristiano P.; Prasain, Nutan; Calzi, Sergio Li; Fortmann, Seth D.; Hu, Ping; Banno, Kimihiko; Jamal, Mohamed; Huang, Chao; Sielski, Micheli S.; Lin, Yang; Huang, Xinxin; Dupont, Mariana D.; Floyd, Jason L.; Prasad, Ram; Longhini, Ana Leda F.; McGill, Trevor J.; Chung, Hyung-Min; Murphy, Michael P.; Kotton, Darrell N.; Boulton, Michael E.; Yoder, Mervin C.; Grant, Maria B.; Pediatrics, School of Medicine
    Human induced pluripotent stem cells (hiPSCs) were differentiated into a specific mesoderm subset characterized by KDR+CD56+APLNR+ (KNA+) expression. KNA+ cells had high clonal proliferative potential and specification into endothelial colony-forming cell (ECFCs) phenotype. KNA+ cells differentiated into perfused blood vessels when implanted subcutaneously into the flank of nonobese diabetic/severe combined immunodeficient mice and when injected into the vitreous of type 2 diabetic mice (db/db mice). Transcriptomic analysis showed that differentiation of hiPSCs derived from diabetics into KNA+ cells was sufficient to change baseline differences in gene expression caused by the diabetic status and reprogram diabetic cells to a pattern similar to KNA+ cells derived from nondiabetic hiPSCs. Proteomic array studies performed on retinas of db/db mice injected with either control or diabetic donor-derived KNA+ cells showed correction of aberrant signaling in db/db retinas toward normal healthy retina. These data provide "proof of principle" that KNA+ cells restore perfusion and correct vascular dysfunction in db/db mice.