Browsing by Author "Li, Qiuhong"

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    Adeno-Associated Virus Overexpression of Angiotensin-Converting Enzyme-2 Reverses Diabetic Retinopathy in Type 1 Diabetes in Mice
    (Elsevier, 2016) Dominguez, James M., II; Hu, Ping; Caballero, Sergio; Moldovan, Leni; Verma, Amrisha; Oudit, Gavin Y.; Li, Qiuhong; Grant, Maria B.; Department of Ophthalmology, School of Medicine
    Angiotensin-converting enzyme (ACE)-2 is the primary enzyme of the vasoprotective axis of the renin angiotensin system that regulates the classic renin angiotensin system axis. We aimed to determine whether local retinal overexpression of adenoassociated virus (AAV)-ACE2 prevents or reverses diabetic retinopathy. Green fluorescent protein (GFP)-chimeric mice were generated to distinguish resident (retinal) from infiltrating bone marrow-derived inflammatory cells and were made diabetic using streptozotocin injections. Retinal digestion using trypsin was performed and acellular capillaries enumerated. Capillary occlusion by GFP(+) cells was used to measure leukostasis. Overexpression of ACE2 prevented (prevention cohort: untreated diabetic, 11.3 ± 1.4; ACE2 diabetic, 6.4 ± 0.9 per mm(2)) and partially reversed (reversal cohort: untreated diabetic, 15.7 ± 1.9; ACE2 diabetic, 6.5 ± 1.2 per mm(2)) the diabetes-associated increase of acellular capillaries and the increase of infiltrating inflammatory cells into the retina (F4/80(+)) (prevention cohort: untreated diabetic, 24.2 ± 6.7; ACE2 diabetic, 2.5 ± 1.6 per mm(2); reversal cohort: untreated diabetic, 56.8 ± 5.2; ACE2 diabetic, 5.6 ± 2.3 per mm(2)). In both study cohorts, intracapillary bone marrow-derived cells, indicative of leukostasis, were only observed in diabetic animals receiving control AAV injections. These results indicate that diabetic retinopathy, and possibly other diabetic microvascular complications, can be prevented and reversed by locally restoring the balance between the classic and vasoprotective renin angiotensin system.
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    Angiotensin Converting Enzyme 2 in Cardiopulmonary Diseases: Ramifications for the Control of SARS-CoV-2
    (American Heart Association, 2020-09) Sharma, Ravindra K.; Stevens, Bruce R.; Obukhov, Alexander G.; Grant, Maria B.; Oudit, Gavin Y.; Li, Qiuhong; Richards, Elaine M.; Pepine, Carl J.; Raizada, Mohan K.; Anatomy and Cell Biology, School of Medicine
    Discovery of angiotensin converting enzyme 2 (ACE2) revealed that the renin angiotensin system (RAS) has two counterbalancing arms. ACE2 is a major player in the protective arm, highly expressed in lungs and gut with the ability to mitigate cardiopulmonary diseases such as inflammatory lung disease. ACE2 also exhibits activities involving gut microbiome, nutrition, and as a chaperone stabilizing the neutral amino acid transporter, B0AT1, in gut. But the current interest in ACE2 arises because it is the cell surface receptor for the novel coronavirus, SARS-CoV-2, to infect host cells, similar to SARS-CoV. This suggests that ACE2 be considered harmful, however because of its important other roles, it is paradoxically a potential therapeutic target for cardiopulmonary diseases including COVID-19, caused by SARS-CoV-2. This review describes the discovery of ACE2, its physiological functions, and its place in the RAS. It illustrates new analyses of the structure of ACE2 that provides better understanding of its actions particularly in lung and gut, shedding of ACE2 by ADAM17 and role of TMPRSS2 in SARS-CoV-2 entry into host cells. Cardiopulmonary diseases are associated with decreased ACE2 activity and the mitigation by increasing ACE2 activity along with its therapeutic relevance are addressed. Finally, the potential use of ACE2 as a treatment target in COVID-19, despite its role to allow viral entry into host cells, is suggested.
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    Restructuring of the Gut Microbiome by Intermittent Fasting Prevents Retinopathy and Prolongs Survival in db/db Mice
    (American Diabetes Association, 2018-09) Beli, Eleni; Yan, Yuanqing; Moldovan, Leni; Vieira, Cristiano P.; Gao, Ruli; Duan, Yaqian; Prasad, Ram; Bhatwadekar, Ashay; White, Fletcher A.; Townsend, Steven D.; Chan, Luisa; Ryan, Caitlin N.; Morton, Daniel; Moldovan, Emil G.; Chu, Fang-I; Oudit, Gavin Y.; Derendorf, Hartmut; Adorini, Luciano; Wang, Xiaoxin X.; Evans-Molina, Carmella; Mirmira, Raghavendra G.; Boulton, Michael E.; Yoder, Mervin C.; Li, Qiuhong; Levi, Moshe; Busik, Julia V.; Grant, Maria B.; Pediatrics, School of Medicine
    Intermittent fasting (IF) protects against the development of metabolic diseases and cancer, but whether it can prevent diabetic microvascular complications is not known. In db/db mice, we examined the impact of long-term IF on diabetic retinopathy (DR). Despite no change in glycated hemoglobin, db/db mice on the IF regimen displayed significantly longer survival and a reduction in DR end points, including acellular capillaries and leukocyte infiltration. We hypothesized that IF-mediated changes in the gut microbiota would produce beneficial metabolites and prevent the development of DR. Microbiome analysis revealed increased levels of Firmicutes and decreased Bacteroidetes and Verrucomicrobia. Compared with db/db mice on ad libitum feeding, changes in the microbiome of the db/db mice on IF were associated with increases in gut mucin, goblet cell number, villi length, and reductions in plasma peptidoglycan. Consistent with the known modulatory effects of Firmicutes on bile acid (BA) metabolism, measurement of BAs demonstrated a significant increase of tauroursodeoxycholate (TUDCA), a neuroprotective BA, in db/db on IF but not in db/db on AL feeding. TGR5, the TUDCA receptor, was found in the retinal primary ganglion cells. Expression of TGR5 did not change with IF or diabetes. However, IF reduced retinal TNF-α mRNA, which is a downstream target of TGR5 activation. Pharmacological activation of TGR5 using INT-767 prevented DR in a second diabetic mouse model. These findings support the concept that IF prevents DR by restructuring the microbiota toward species producing TUDCA and subsequent retinal protection by TGR5 activation.