Role of interleukin-10 in the neuroprotective effect of the Angiotensin Type 2 Receptor agonist, compound 21, after ischemia/reperfusion injury

Introduction: We and others have shown that the angiotensin type 2 (AT2) receptor agonist, compound 21 (C21), provides neuroprotection and enhances recovery in rodent stroke models yet the mechanism involved is not known. Moreover, C21 treatment is associated with an anti-inflammatory response. Here we tested the hypothesis that C21 mediates neuroprotection by upregulating the neuroprotective and anti-inflammatory cytokine interleukin (IL)-10. Methods: Wistar rats (n=16) were subjected to 3 h MCA suture occlusion and treated at reperfusion with C21 (0.03 mg/kg) ± IL-10 neutralizing antibody (0.1 μg/kg) both given I.P. Endpoints at 24 h included: Infarct size, behavioral outcome, and molecular analysis. Primary rat neurons were used to test the direct neuroprotective effect of C21 in vitro. Results (Table): C21 treatment upregulated IL-10 expression (1797±89 vs 1333±84 pg/mg) and increased IL-10 downstream survival signals, STAT3 and AKT phosphorylation, in the stroked hemisphere compared to saline. Anti-IL-10 co-treatment blocked the C21 induced reduction in infarct size and inflammatory/apoptotic markers, and blunted the improvement in behavioral outcome, as well as survival signal activation. In vitro (n=4), C21 treatment failed to directly protect ischemic neurons against oxygen glucose deprivation/reperfusion (OGD/R) insult as measured by LDH release (other cell death markers are to be analyzed), but was able to upregulate IL-10 in normoxic neurons (0.3±0.02 vs 0.23±0.01) suggesting a potential indirect neuroprotective effect. Conclusion: C21 provides acute neuroprotection after ischemia reperfusion injury through neuronal IL-10 upregulation. Further understanding of the mechanism of action will pave the way for translating C21 and future AT2 agonists to the clinical stroke setting.

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Angiotensin Type 2 Receptor Agonist Compound 21 Reduces Vascular Injury and Myocardial Fibrosis in Stroke-Prone Spontaneously Hypertensive Rats

Hypertension ◽

10.1161/hypertensionaha.111.180158 ◽

2012 ◽

Vol 59 (2) ◽

pp. 291-299 ◽

Cited By ~ 118

Author(s):

Asia Rehman ◽

Avshalom Leibowitz ◽

Naoki Yamamoto ◽

Yohann Rautureau ◽

Pierre Paradis ◽

...

Keyword(s):

Myocardial Fibrosis ◽

Vascular Injury ◽

Receptor Agonist ◽

Spontaneously Hypertensive Rats ◽

Hypertensive Rats ◽

Spontaneously Hypertensive ◽

Angiotensin Type 2 Receptor ◽

Compound 21 ◽

Angiotensin Type

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Anti‐inflammatory action of angiotensin‐(1–7) and the angiotensin type 2 receptor agonist Compound 21 in hypothalamic microglia

The FASEB Journal ◽

10.1096/fasebj.27.1_supplement.692.3 ◽

2013 ◽

Vol 27 (S1) ◽

Author(s):

Meng Liu ◽

Peng Shi ◽

Ulrike Muscha Steckelings ◽

Colin Sumners

Keyword(s):

Receptor Agonist ◽

Angiotensin Type 2 Receptor ◽

Compound 21 ◽

Anti Inflammatory ◽

Inflammatory Action ◽

Angiotensin Type

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The angiotensin type 2 receptor agonist Compound 21 elicits cerebroprotection in endothelin-1 induced ischemic stroke

Neuropharmacology ◽

10.1016/j.neuropharm.2014.01.044 ◽

2014 ◽

Vol 81 ◽

pp. 134-141 ◽

Cited By ~ 50

Author(s):

Jason P. Joseph ◽

Adam P. Mecca ◽

Robert W. Regenhardt ◽

Douglas M. Bennion ◽

Vermali Rodríguez ◽

...

Keyword(s):

Ischemic Stroke ◽

Receptor Agonist ◽

Endothelin 1 ◽

Angiotensin Type 2 Receptor ◽

Compound 21 ◽

Angiotensin Type

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Mas mediated cerebroprotective action of the angiotensin type 2 receptor agonist Compound 21 in ischemic stroke.

The FASEB Journal ◽

10.1096/fasebj.27.1_supplement.693.6 ◽

2013 ◽

Vol 27 (S1) ◽

Author(s):

Neal Anil Patel ◽

Jason Joseph ◽

David Pioquinto ◽

Jacob Ludin ◽

David Greenstein ◽

...

Keyword(s):

Ischemic Stroke ◽

Receptor Agonist ◽

Angiotensin Type 2 Receptor ◽

Compound 21 ◽

Angiotensin Type

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NEUROPROTECTIVE ROLE OF ASCORBIC ACID: ANTIOXIDANT AND NON-ANTIOXIDANT FUNCTIONS

Asian Journal of Pharmaceutical and Clinical Research ◽

10.22159/ajpcr.2018.v11i10.27318 ◽

2018 ◽

Vol 11 (10) ◽

pp. 30 ◽

Cited By ~ 1

Author(s):

Arun Kumar ◽

Reena V Saini ◽

Adesh K Saini

Keyword(s):

Ascorbic Acid ◽

Vitamin C ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Glutamate Toxicity ◽

Cellular Functions ◽

Dietary Antioxidant ◽

The Central Nervous System

Ascorbic acid (AA) or Vitamin C is an important antioxidant which participates in numerous cellular functions. Although in human plasma its concentration is in micromolars but it reaches millimolar concentrations in most of the human tissues. The high ascorbate cellular concentrations are generated and maintained by a specific sodium-dependent Vitamin C transporter type 2 (SVCT2, member of Slc23 family). Metabolic processes recycle Vitamin C from its oxidized forms (ascorbate) inside the cells. AA concentration is highest in the neurons of the central nervous system (CNS) of mammals, and deletion of its transporter affects mice brain and overall survival. In the CNS, intracellular ascorbate serves several functions including antioxidant protection, peptide amidation, myelin formation, synaptic potentiation, and protection against glutamate toxicity. SVCT2 maintains neuronal ascorbate content in CNS which has relevance for neurodegenerative diseases such as Alzheimer’s, Parkinson’s, and Huntington’s disease. As ascorbate supplements decrease infarct size in ischemia-reperfusion injury and protect neurons from oxidative damage, it is a vital dietary antioxidant. The aim of this review is to assess the role of the SVCT2 in regulating neuronal ascorbate homeostasis in CNS and the extent to which ascorbate affects brain function as an antioxidant.

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Abstract P288: Systemic Administration of an Angiotensin Type-2 Receptor Agonist Decreases Renal Regulatory T Cells

Hypertension ◽

10.1161/hyp.70.suppl_1.p288 ◽

2017 ◽

Vol 70 (suppl_1) ◽

Author(s):

Ellen E Gillis ◽

Jennifer C Sullivan

Keyword(s):

T Cells ◽

Regulatory T Cells ◽

Critical Role ◽

High Dose ◽

Ang Ii ◽

Osmotic Minipump ◽

Angiotensin Type 2 Receptor ◽

Angiotensin Type

There is increasing evidence supporting a critical role of the immune system in the development of hypertension. Our lab has previously reported sex differences in the renal T cell profile in both Spontaneously Hypertensive Rats (SHR) and Angiotensin II (Ang II) models of hypertension, with females having more anti-inflammatory regulatory T cells (Tregs) than males. Ang II has a well-defined role in the activation of pro-inflammatory T cells in hypertension via the angiotensin type-1 receptor (AT1R). Less is known about the role of the angiotensin type-2 receptor (AT2R) in the regulation of immune cells, although the AT2R has been shown to be cardioprotective and AT2R expression is greater in females than males. Based on the potential anti-hypertensive role of AT2Rs, we hypothesized that administration of an AT2R agonist, Compound 21 (C21), would increase renal Tregs, and this increase would be greater in females due to greater AT2R expression. Male and female SHR (10 weeks of age, n=3-4) were implanted with telemetry units for continuous monitoring of mean arterial pressure (MAP). Following 10 days of recovery, baseline MAP was recorded for 5 days. Rats were then divided into the following treatment groups: surgical controls, low dose C21 (150 ng/kg/min, sc by osmotic minipump), high dose C21 (300 ng/kg/min, sc by osmotic minipump). Kidneys were harvested after 2 weeks of treatment and flow cytometry was performed on whole kidney homogenates. MAP was not altered by C21 treatment in males (137±4 vs 134±4 vs 134±4 mmHg; n.s.) or females (128±2 vs 136±5 vs 134±4 mmHg; n.s.). Interestingly, despite having no effect on MAP, there was a significant decrease in renal CD3 + CD4 + FoxP3 + Tregs in females following both low and high doses of C21 (data expressed as % CD3 + CD4 + cells: 6±0.6 vs 3±0.6 vs 3.5±1.3 %, respectively; p=0.02). Tregs decrease in males following the high dose of C21 only (data expressed as % CD3 + CD4 + cells: 3.3±0.3 vs 3.3±0.5 vs 1.7±0.7 %, respectively; p=0.05). Total CD3 + T cells, CD3 + CD4 + T cells, and Th17 cells were not altered by C21 treatment. In conclusion, AT2R activation suppresses renal Tregs, and females are more sensitive than males. These data suggest a novel role for AT2R regulation in the kidney in hypertension.

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Abstract WP101: Involvement of the Contralesional Angiotensin Type 2 Receptor in Compound 21 Mediated Functional Recovery After Stroke

Stroke ◽

10.1161/str.47.suppl_1.wp101 ◽

2016 ◽

Vol 47 (suppl_1) ◽

Author(s):

Abdelrahman Y Fouda ◽

Tauheed Ishrat ◽

Heba Ahmed ◽

Bindu Pillai ◽

Sandeep Artham ◽

...

Keyword(s):

Western Blotting ◽

Functional Recovery ◽

Artery Occlusion ◽

Behavioral Outcome ◽

Brain Hemisphere ◽

Angiotensin Type 2 Receptor ◽

Male Wistar Rats ◽

Compound 21 ◽

Angiotensin Type

Introduction: We have recently shown that the angiotensin type 2 receptor (AT2R) agonist, compound 21 (C21), provides sustained functional recovery after ischemic stroke. This was associated with upregulation of the AT2R and the neurotrophin, brain derived neurotrophic factor (BDNF), in the contralesional brain hemisphere. Here, we aimed to study the contribution of this hemisphere in C21 mediated functional recovery after stroke through localized knockdown of the AT2R. Methods: male wistar rats (34) received two intrastriatal injections of short hairpin RNA (shRNA) lentiviral particles against AT2R, or non-targeting control vector (NTC) into the left brain hemisphere to achieve localized AT2R knockdown. After 14 days, rats were subjected to 90 minutes right middle cerebral artery occlusion (MCAO) and received either C21 (0.03 mg/kg) or saline at reperfusion (IV) then daily (IP) for 7 days. Rats were blindly assessed for behavioral outcome up to 10 days as well as molecular analysis. Results (table): PCR and Western blotting confirmed successful knockdown of the AT2R in the left (contralesional) hemisphere by about 50%. All groups showed worsened outcome on days 1 to 3 then recovered on days 7 to 10. The C21/NTC group showed better behavioral outcome compared to other groups at days 7 and 10, while the saline/shRNA group was associated with the least recovery. Using Western blotting, C21/NTC group showed higher BDNF and lower proBDNF (pro-form) levels in the ischemic and contralesional hemispheres respectively. Expression of the pro-apoptotic P75NTR receptor of proBDNF was decreased with C21 treatment irrespective of AT2R knockdown. Conclusion: Contralesional AT2R could be involved in C21 mediated functional recovery after stroke.

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