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Bakkar NMZ, Mougharbil N, Mroueh A, Kaplan A, Eid AH, Fares S, Zouein FA, El-Yazbi AF. Worsening baroreflex sensitivity on progression to type 2 diabetes: localized vs. systemic inflammation and role of antidiabetic therapy. Am J Physiol Endocrinol Metab 2020; 319:E835-E851. [PMID: 32865011 DOI: 10.1152/ajpendo.00145.2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Cardiac autonomic neuropathy (CAN) is an early cardiovascular manifestation of type 2 diabetes (T2D) that constitutes an independent risk factor for cardiovascular mortality and morbidity. Nevertheless, its underlying pathophysiology remains poorly understood. We recently showed that localized perivascular adipose tissue (PVAT) inflammation underlies the incidence of parasympathetic CAN in prediabetes. Here, we extend our investigation to provide a mechanistic framework for the evolution of autonomic impairment as the metabolic insult worsens. Early metabolic dysfunction was induced in rats fed a mild hypercaloric diet. Two low-dose streptozotocin injections were used to evoke a state of late decompensated T2D. Cardiac autonomic function was assessed by invasive measurement of baroreflex sensitivity using the vasoactive method. Progression into T2D was associated with aggravation of CAN to include both sympathetic and parasympathetic arms. Unlike prediabetic rats, T2D rats showed markers of brainstem neuronal injury and inflammation as well as increased serum levels of IL-1β. Experiments on PC12 cells differentiated into sympathetic-like neurons demonstrated that brainstem injury observed in T2D rats resulted from exposure to possible proinflammatory mediators in rat serum rather than a direct effect of the altered metabolic profile. CAN and the associated cardiovascular damage in T2D only responded to combined treatment with insulin to manage hyperglycemia in addition to a nonhypoglycemic dose of metformin or pioglitazone providing an anti-inflammatory effect, coincident with the effect of these combinations on serum IL-1β. Our present results indicate that CAN worsening upon progression to T2D involves brainstem inflammatory changes likely triggered by systemic inflammation.
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Affiliation(s)
- Nour-Mounira Z Bakkar
- Department of Pharmacology and Toxicology, Faculty of Medicine, The American University of Beirut, Beirut, Lebanon
| | - Nahed Mougharbil
- Department of Pharmacology and Toxicology, Faculty of Medicine, The American University of Beirut, Beirut, Lebanon
| | - Ali Mroueh
- Department of Pharmacology and Toxicology, Faculty of Medicine, The American University of Beirut, Beirut, Lebanon
| | - Abdullah Kaplan
- Department of Pharmacology and Toxicology, Faculty of Medicine, The American University of Beirut, Beirut, Lebanon
| | - Ali H Eid
- Department of Pharmacology and Toxicology, Faculty of Medicine, The American University of Beirut, Beirut, Lebanon
- College of Medicine, Qatar University, Doha, Qatar
| | - Souha Fares
- Rafic Hariri School of Nursing, The American University of Beirut, Beirut, Lebanon
| | - Fouad A Zouein
- Department of Pharmacology and Toxicology, Faculty of Medicine, The American University of Beirut, Beirut, Lebanon
| | - Ahmed F El-Yazbi
- Department of Pharmacology and Toxicology, Faculty of Medicine, The American University of Beirut, Beirut, Lebanon
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt
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Elkhatib MAW, Mroueh A, Rafeh RW, Sleiman F, Fouad H, Saad EI, Fouda MA, Elgaddar O, Issa K, Eid AH, Eid AA, Abd-Elrahman KS, El-Yazbi AF. Amelioration of perivascular adipose inflammation reverses vascular dysfunction in a model of nonobese prediabetic metabolic challenge: potential role of antidiabetic drugs. Transl Res 2019; 214:121-143. [PMID: 31408626 DOI: 10.1016/j.trsl.2019.07.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 06/28/2019] [Accepted: 07/22/2019] [Indexed: 12/12/2022]
Abstract
The onset of vascular impairment precedes that of diagnostic hyperglycemia in diabetic patients suggesting a vascular insult early in the course of metabolic dysfunction without a well-defined mechanism. Mounting evidence implicates adipose inflammation in the pathogenesis of insulin resistance and diabetes. It is not certain whether amelioration of adipose inflammation is sufficient to preclude vascular dysfunction in early stages of metabolic disease. Recent findings suggest that antidiabetic drugs, metformin, and pioglitazone, improve vascular function in prediabetic patients, without an indication if this protective effect is mediated by reduction of adipose inflammation. Here, we used a prediabetic rat model with delayed development of hyperglycemia to study the effect of metformin or pioglitazone on adipose inflammation and vascular function. At the end of the metabolic challenge, these rats were neither obese, hypertensive, nor hyperglycemic. However, they showed increased pressor responses to phenylephrine and augmented aortic and mesenteric contraction. Vascular tissues from prediabetic rats showed increased Rho-associated kinase activity causing enhanced calcium sensitization. An elevated level of reactive oxygen species was seen in aortic tissues together with increased Transforming growth factor β1 and Interleukin-1β expression. Although, no signs of systemic inflammation were detected, perivascular adipose inflammation was observed. Adipocyte hypertrophy, increased macrophage infiltration, and elevated Transforming growth factor β1 and Interleukin-1β mRNA levels were seen. Two-week treatment with metformin or pioglitazone or switching to normal chow ameliorated adipose inflammation and vascular dysfunction. Localized perivascular adipose inflammation is sufficient to trigger vascular dysfunction early in the course of diabetes. Interfering with this inflammatory process reverses this early abnormality.
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Affiliation(s)
- Mohammed A W Elkhatib
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt
| | - Ali Mroueh
- Department of Pharmacology and Toxicology, Faculty of Medicine, The American University of Beirut, Beirut, Lebanon
| | - Rim W Rafeh
- Department of Pharmacology and Toxicology, Faculty of Medicine, The American University of Beirut, Beirut, Lebanon
| | - Fatima Sleiman
- Department of Pharmacology and Toxicology, Faculty of Medicine, The American University of Beirut, Beirut, Lebanon
| | - Hosny Fouad
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt
| | - Evan I Saad
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt
| | - Mohamed A Fouda
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt
| | - Ola Elgaddar
- Department of Chemical Pathology, Medical Research Institute, Alexandria University, Alexandria, Egypt
| | - Khodr Issa
- Department of Pharmacology and Toxicology, Faculty of Medicine, The American University of Beirut, Beirut, Lebanon
| | - Ali H Eid
- Department of Pharmacology and Toxicology, Faculty of Medicine, The American University of Beirut, Beirut, Lebanon; Department of Biomedical Sciences, Qatar University, Doha, Qatar
| | - Assaad A Eid
- Department of Anatomy, Cell Biology and Physiology, Faculty of Medicine, The American University of Beirut, Beirut, Lebanon
| | - Khaled S Abd-Elrahman
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt; Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa Brain and Mind Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Ahmed F El-Yazbi
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt; Department of Pharmacology and Toxicology, Faculty of Medicine, The American University of Beirut, Beirut, Lebanon.
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