O A Carretero

Henry Ford Hospital, Detroit, Michigan, United States

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Publications (352)2006.45 Total impact

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    ABSTRACT: Systemic lupus erythematosus is an autoimmune disease characterized by the development of auto antibodies against a variety of self-antigens and deposition of immune complexes that lead to inflammation, fibrosis and end organ damage. Up to 60% of lupus patients develop nephritis and renal dysfunction leading to kidney failure. N-acetyl-seryl-aspartyl-lysyl-proline, i.e. Ac-SDKP, is a natural tetrapeptide that in hypertension prevents inflammation and fibrosis in heart, kidney, and vasculature. In experimental autoimmune myocarditis Ac-SDKP prevents cardiac dysfunction by decreasing innate and adaptive immunity. It has also been reported that Ac-SDKP ameliorates lupus nephritis in mice. We hypothesize that Ac-SDKP prevents lupus nephritis in mice by decreasing complement C5-9, proinflammatory cytokines, and immune cell infiltration. Lupus mice treated with Ac-SDKP for 20 weeks had significantly lower renal levels of macrophage and T cell infiltration and proinflammatory chemokine/cytokines. In addition, our data demonstrate for the first time that in lupus mouse Ac-SDKP prevented the increase in complement C5-9, RANTES, MCP-5 and ICAM-1 kidney expression and it prevented the decline of glomerular filtration rate. Ac-SDKP treated lupus mice had a significant improvement in renal function and lower levels of glomerular damage. Ac-SDKP had no effect on the production of autoantibodies. The protective Ac-SDKP effect is most likely achieved by targeting the expression of proinflammatory chemokines/cytokines, ICAM-1 and immune cell infiltration in the kidney, either directly or via C5-9 proinflammatory arm of complement system. Copyright © 2015, American Journal of Physiology - Renal Physiology.
    American journal of physiology. Renal physiology 03/2015; 308(10):ajprenal.00039.2015. DOI:10.1152/ajprenal.00039.2015
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    ABSTRACT: Afferent (Af-Art) and efferent arterioles (Ef-Art) resistance regulate glomerular capillary pressure (GCP). The nephron regulates Af-Art resistance via: 1) vasoconstrictor tubuloglomerular feedback (TGF), initiated in the macula densa via Na/K/2Cl cotransporters (NKCC2); and 2) vasodilator connecting tubuloglomerular feedback (CTGF), initiated in connecting tubules (CT) via epithelial Na channels (ENaC). Furosemide inhibits NKCC2 and TGF. Benzamil inhibits ENaC and CTGF. In vitro, CTGF dilates preconstricted Af-Arts. In vivo, benzamil decreases stop-flow pressure (PSF), suggesting that CTGF antagonizes TGF; however, even when TGF is blocked, CTGF does not increase PSF, suggesting there is another mechanism antagonizing CTGF. We hypothesize that in addition to NKCC2, activation of Na/H exchanger (NHE) antagonizes CTGF, and when both are blocked CTGF dilates Af-Arts and this effect is blocked by a CTGF inhibitor benzamil. Using micropuncture, we studied the effects of transport inhibitors on TGF responses by measuring PSF while increasing nephron perfusion from 0 to 40 nL/min. Control TGF response (-7.9±0.2 mmHg) was blocked by furosemide (-0.4±0.2 mm Hg; P<0.001). Benzamil restored TGF in the presence of furosemide (furosemide: -0.2±0.1 vs furosemide+benzamil: -4.3±0.3 mmHg, P<0.001). With furosemide and NHE inhibitor, dimethylamiloride (DMA), increase in tubular flow increased PSF (furosemide+DMA: 2.7±0.5 mmHg, n=6), and benzamil blocked this (furosemide+DMA+benzamil: -1.1±0.2 mmHg, P<0.01, n=6). We conclude that NHE in the nephron decreases PSF (Af-Art constriction) when NKCC2 and ENaC are inhibited, suggesting that in the absence of NKCC2, NHE causes a TGF response and that CTGF dilates the Af-Art when TGF is blocked with NKCC2 and NHE inhibitors. Copyright © 2014, American Journal of Physiology - Renal Physiology.
    American journal of physiology. Renal physiology 02/2015; 308(9):ajprenal.00605.2014. DOI:10.1152/ajprenal.00605.2014
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    ABSTRACT: Thick ascending limbs reabsorb 30% of the filtered NaCl load. Nitric oxide (NO) produced by NO synthase 3 (NOS3) inhibits NaCl transport by this segment. In contrast, chronic angiotensin II (Ang II) infusion increases net thick ascending limb transport. NOS3 activity is regulated by changes in expression and phosphorylation at threonine 495 (T495) and serine 1177 (S1177), inhibitory and stimulatory sites respectively. We hypothesized that NO production by thick ascending limbs is impaired by chronic Ang II-infusion, due to reduced NOS3 expression, increased phosphorylation of T495 and decreased phosphorylation of S1177. Rats were infused with 200 ng/kg/min Ang II or vehicle for 1 and 5 days. Ang II infusion for 5 days decreased NOS3 expression by 40 ± 12% (p < 0.007; n = 6) and increased T495 phosphorylation by 147 ± 26 % (p < 0.008; n = 6). One-day Ang-II infusion had no significant effect. NO production in response to endothelin-1 was blunted in thick ascending limbs from Ang II-infused animals (Ang II -0.01 ± 0.06 AFU/min vs. 0.17 ± 0.02 AFU/min in controls; p<0.01). This was not due to endothelin-1 receptor expression. Phosphatidylinositol 3,4,5-triphosphate (PIP3)-induced NO production was also reduced in Ang II-infused rats (Ang II -0.07 ± 0.06 AFU/min vs. 0.13 ± 0.04 AFU/min in controls; p<0.03), and this correlated with an impaired ability of PIP3 to increase S1177 phosphorylation. We conclude that in Ang II-induced hypertension NO production by thick ascending limbs is impaired due to decreased NOS3 expression and altered phosphorylation.-
    American journal of physiology. Renal physiology 11/2014; 308(2):ajprenal.00279.2014. DOI:10.1152/ajprenal.00279.2014
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    ABSTRACT: Inflammation has been proposed as a key component in the development of hypertension and cardiac remodeling associated with different cardiovascular diseases. However, the role of the proinflammatory cytokine interleukin-6 in the chronic stage of hypertension is not well defined. Here, we tested the hypothesis that deletion of interleukin-6 protects against the development of hypertension, cardiac inflammation, fibrosis, remodeling and dysfunction induced by high salt diet and angiotensin II (Ang II).
    Journal of Hypertension 10/2014; 33(1). DOI:10.1097/HJH.0000000000000358
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    ABSTRACT: Thymosin β4 (Tβ4) promotes cell survival, angiogenesis, tissue regeneration and reduces inflammation. Cardiac rupture after myocardial infarction (MI) is mainly the consequence of excessive regional inflammation, whereas cardiac dysfunction after MI results from a massive cardiomyocyte loss and cardiac fibrosis. It is possible that Tβ4 reduces incidence of cardiac rupture post-MI via anti-inflammatory actions and that it decreases adverse cardiac remodeling and improves cardiac function by promoting cardiac cell survival and cardiac repair. C57BL/6 mice were subjected to MI and treated with either vehicle or Tβ4 (1.6 mg/kg/day i.p. via osmotic minipump) for 7 days or 5 weeks. Mice were assessed for 1) cardiac remodeling and function by echocardiography; 2) inflammatory cell infiltration, capillary density, myocyte apoptosis and interstitial collagen fraction (ICF) histopathologically; 3) gelatinolytic activity by in situ zymography; and 4) expression of intercellular adhesion molecule-1 (ICAM-1) and p53 by immunoblot. Tβ4 reduced cardiac rupture that was associated with decrease in the numbers of infiltrating inflammatory cells and apoptotic myocytes, decrease in gelatinolytic activity and ICAM-1 and p53 expression, as well as the increase in the numbers of CD31-positive cells. Five-week treatment with Tβ4 ameliorated left ventricular dilation, improved cardiac function, and markedly reduced ICF and increased capillary density. In murine model of acute MI, Tβ4 not only decreased mortality rate as a result of cardiac rupture but also significantly improved cardiac function after MI. Thus the use of Tβ4 could be explored as an alternative therapy in preventing cardiac rupture and restoring cardiac function in patients with MI.
    AJP Heart and Circulatory Physiology 07/2014; 307(5). DOI:10.1152/ajpheart.00129.2014
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    ABSTRACT: The afferent arteriole (Af-Art) controls glomerular capillary pressure, an important determinant of glomerular injury. Af-Art myogenic response is mediated by ATP, and ATP signaling is in turn mediated by 20-HETE. Dahl salt-sensitive rats (Dahl SS) have decreased renal 20-HETE production. We hypothesized that Dahl SS have an impaired myogenic response and constrictor response to ATP, due to decreased 20-HETE. Af-Arts from Dahl SS or Dahl salt resistant rats (Dahl SR) were microdissected and perfused. When myogenic response was induced by increasing Af-Art perfusion pressure from 60 to 140 mmHg, luminal Af-Art diameter decreased in Dahl SR but not in Dahl SS (-3.1±0.8 vs. 0.5±0.8 µm, P<0.01). The 20-HETE antagonist 20-HEDE (10(-6)M) blocked the myogenic response in Dahl SR but had no effect in Dahl SS. Addition of a subconstrictor concentration of 20-HETE (but not a subconstrictor concentration of norepinephrine) restored the myogenic response in Dahl SS. We then perfused Af-Arts at 60 mmHg and tested the effects of the ATP analog α,β-methylene-ATP (10-6M). Maximum ATP-induced constriction was attenuated in Dahl SS compared to Dahl SR (1.5±0.5 vs. 7.4±0.8 µm, P<0.001). 20-HEDE attenuated ATP-induced Af-Art constriction in Dahl SR but not in Dahl SS, and consequently, ATP-induced constriction was no longer different between strains. In conclusion, Dahl SS have an impaired myogenic response and ATP-induced Af-Art constriction due to a decrease in Af-Art 20-HETE. The impaired myogenic responses may contribute to the nephrosclerosis that develops in Dahl SS.
    American journal of physiology. Renal physiology 07/2014; 307(5). DOI:10.1152/ajprenal.00283.2014
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    ABSTRACT: Increasing Na delivery to epithelial Na channels (ENaC) in the connecting tubule (CNT) dilates the afferent arteriole (Af-Art), a process we call connecting tubule glomerular feedback (CTGF). We hypothesize that aldosterone sensitizes CTGF via a nongenomic mechanism that stimulates CNT ENaC via the aldosterone receptor GPR30. Rabbit Af-Arts and their adherent CNTs were microdissected and simultaneously perfused. Two consecutive CTGF curves were elicited by increasing luminal NaCl in the CNT. During the control period, the concentration of NaCl that elicited a half-maximal response (EC50) was 37.0±2.0 mmol/L; addition of aldosterone 10-8 mol/L to the CNT lumen caused a left-shift (decrease) in EC50 to 19.3±1.3 mmol/L (P=0.001 vs. Control; n=6). Neither the transcription inhibitor actinomycin D (control EC50=34.7±1.9 mmol/L; aldosterone+actinomycin D EC50=22.6±1.6 mmol/L; n=6; P < 0.001) nor the translation inhibitor cycloheximide (control EC50=32.4±4.3 mmol/L; aldosterone+cycloheximide EC50=17.4±3.3 mmol/L; n=6; P < 0.001) prevented the effect of aldosterone. The aldosterone antagonist eplerenone prevented the sensitization of CTGF by aldosterone (control EC50=33.2±1.7 mmol/L; aldosterone+eplerenone EC50=33.5±1.3 mmol/L; n=7). The GPR30 receptor blocker G-36 blocked the sensitization of CTGF by aldosterone (aldosterone EC50=16.5±1.9 mmol/L; aldosterone+G-36 EC50=29.0±2.1 mmol/L; n=7; P < 0.001). Finally, we found that the sensitization of CTGF by aldosterone was mediated, at least in part, by the sodium/hydrogen exchanger (NHE). We conclude that aldosterone in the CNT lumen sensitizes CTGF via a nongenomic effect involving GPR30 receptors and NHE. Sensitized CTGF induced by aldosterone may contribute to renal damage by increasing Af-Art dilation and glomerular capillary pressure (glomerular barotrauma).
    American journal of physiology. Renal physiology 06/2014; 307(4). DOI:10.1152/ajprenal.00072.2014
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    ABSTRACT: The activation of angiotensin II type 2 receptor (AT2R) has been considered cardioprotective. However, there are controversial findings regarding the role of overexpressing AT2R in the heart. Using transgenic mice with different levels of AT2R gene overexpression in the heart (1, 4, or 9 copies of the AT2R transgene: Tg(1), Tg(4), or Tg(9)), we studied the effect of AT2R overexpression on left ventricular remodeling and dysfunction post-myocardial infarction (MI). Tg(1), Tg(4), Tg(9), and their wild-type littermates were divided into (1) sham MI, (2) MI plus vehicle, and (3) MI plus AT2R antagonist. Treatments were started 4 weeks after MI and continued for 8 weeks. AT2R protein and mRNA expression in the heart was significantly increased in transgenic mice, and the increase positively correlated with copies of the transgene. AT1R protein and mRNA expression remained unchanged in Tg(1) and Tg(4) but slightly increased in Tg(9) mice. Systolic blood pressure and cardiac phenotypes did not differ among strains under basal conditions. MI caused myocardial hypertrophy, interstitial fibrosis, ventricular dilatation, and dysfunction associated with increased protein expression of Nox2 and transforming growth factor β1. These pathological responses were diminished in Tg(1) and Tg(4) mice. Moreover, the protective effects of AT2R were abolished by AT2R antagonist and also absent in Tg(9) mice. We thus conclude that whether overexpression of AT2R is beneficial or detrimental to the heart is largely dependent on expression levels and possibly via regulations of Nox2 and transforming growth factor β1 signaling pathways.
    Hypertension 04/2014; 63(6). DOI:10.1161/HYPERTENSIONAHA.114.03247
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    ABSTRACT: Connecting tubule glomerular feedback (CTGF) is a mechanism in which Na reabsorption in the connecting tubule (CNT) causes afferent arteriole (Af-Art) dilation. CTGF is mediated by eicosanoids, including prostaglandins and epoxyeicosatrienoic acids; however, their exact nature and source remain unknown. We hypothesized that during CTGF, the CNT releases prostaglandin E2, which binds its type 4 receptor (EP4) and dilates the Af-Art. Rabbit Af-Arts with the adherent CNT intact were microdissected, perfused, and preconstricted with norepinephrine. CTGF was elicited by increasing luminal NaCl in the CNT from 10 to 80 mmol/L. We induced CTGF with or without the EP4 receptor blocker ONO-AE3-208 added to the bath in the presence of the epoxyeicosatrienoic acid synthesis inhibitor MS-PPOH. ONO-AE3-208 abolished CTGF (control, 9.4±0.5; MS-PPOH+ONO-AE3-208, -0.6±0.2 μm; P<0.001; n=6). To confirm these results, we used a different, specific EP4 blocker, L161982 (10(-5) mol/L), that also abolished CTGF (control, 8.5±0.9; MS-PPOH+L161982, 0.8±0.4 μm; P<0.001; n=6). To confirm that the eicosanoids that mediate CTGF are released from the CNT rather than the Af-Art, we first disrupted the Af-Art endothelium with an antibody and complement. Endothelial disruption did not affect CTGF (7.9±0.9 versus 8.6±0.6 μm; P=NS; n=7). We then added arachidonic acid to the lumen of the CNT while maintaining zero NaCl in the perfusate. Arachidonic acid caused dose-dependent dilation of the attached Af-Art (from 8.6±1.2 to 15.3±0.7 μm; P<0.001; n=6), and this effect was blocked by ONO-AE3-208 (10(-7) mol/L). We conclude that during CTGF, the CNT releases prostaglandin E2, which acts on EP4 on the Af-Art inducing endothelium-independent dilation.
    Hypertension 09/2013; 63(3). DOI:10.1161/HYPERTENSIONAHA.113.02040
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    ABSTRACT: In Dahl salt-sensitive rats (Dahl SS), glomerular capillary pressure increases in response to high salt intake and this is accompanied by significant glomerular injury compared with spontaneously hypertensive rats with similar blood pressure. Glomerular capillary pressure is controlled mainly by afferent arteriolar resistance, which is regulated by the vasoconstrictor tubule glomerular feedback (TGF) and the vasodilator connecting TGF (CTGF). We hypothesized that Dahl SS have a decreased TGF response and enhanced TGF resetting compared with spontaneously hypertensive rats, and that these differences are attributable in part to an increase in CTGF. In vivo, using micropuncture we measured stop-flow pressure (a surrogate of glomerular capillary pressure). TGF was calculated as the maximal decrease in stop-flow pressure caused by increasing nephron perfusion, TGF resetting as the attenuation in TGF induced by high salt diet, and CTGF as the difference in TGF response before and during CTGF inhibition with benzamil. Compared with spontaneously hypertensive rats, Dahl SS had (1) lower TGF responses in normal (6.6±0.1 versus 11.0±0.2 mm Hg; P<0.001) and high-salt diets (3.3±0.1 versus 10.1±0.3 mm Hg; P<0.001), (2) greater TGF resetting (3.3±0.1 versus 1.0±0.3 mm Hg; P<0.001), and (3) greater CTGF (3.4±0.4 versus 1.2±0.1 mm Hg; P<0.001). We conclude that Dahl SS have lower TGF and greater CTGF than spontaneously hypertensive rats, and that CTGF antagonizes TGF. Furthermore, CTGF is enhanced by a high-salt diet and contributes significantly to TGF resetting. Our findings may explain in part the increase in vasodilatation, glomerular capillary pressure, and glomerular damage in SS hypertension during high salt intake.
    Hypertension 08/2013; 62(4). DOI:10.1161/HYPERTENSIONAHA.113.01846
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    ABSTRACT: We previously reported that N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) reduces fibrosis and inflammation (macrophages and mast cells). However, it is not known whether Ac-SDKP decreases collagen cross-linking and lymphocyte infiltration; lymphocytes modulate both collagen cross-linking and extracellular matrix formation in hypertension. Thus, we hypothesized that 1) in angiotensin (Ang) II-induced hypertension, Ac-SDKP prevents increases in cross-linked and total collagen by down-regulating lysyl oxidase (LOX), the enzyme responsible for cross-linking, and 2) these effects are associated with decreased a) pro-fibrotic cytokine TGF-β and b) the pro-inflammatory transcription factor nuclear factor κB (NFκB), and c) CD4+/CD8+ lymphocyte infiltration. We induced hypertension in rats by infusing Ang II either alone or combined with Ac-SDKP for 3 weeks. While Ac-SDKP failed to lower blood pressure or left ventricular hypertrophy, it did prevent Ang II-induced increases in 1) cross-linked and total collagen, 2) LOX mRNA expression and LOXL1 protein, 3) TGF-β expression, 4) nuclear translocation of NFκB, 5) CD4+/CD8+ lymphocyte infiltration and 6) CD68+ macrophages infiltration. In addition, we found a positive correlation between CD4+ infiltration and LOXL1 expression. In conclusion, the effect of Ac-SDKP on collagen cross-linking and total collagen may be due to reduced TGF-β1, LOXL1 and lymphocyte and macrophages infiltration, and its effect on inflammation could be due to lower NFκB.
    Clinical Science 07/2013; 126(1-2). DOI:10.1042/CS20120619
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    ABSTRACT: Previously, we found thymosin β4 (Tβ4) is upregulated in glomerulosclerosis and required for angiotensin II-induced expression of plasminogen activator inhibitor-1 (PAI-1) in glomerular endothelial cells. Tβ4 has beneficial effects in dermal and corneal wound healing and heart disease, yet its effects in kidney disease are unknown. Here we studied renal fibrosis in wild-type and PAI-1 knockout mice following unilateral ureteral obstruction to explore the impact of Tβ4 and its prolyl oligopeptidase tetrapeptide degradation product, N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP), in renal fibrosis. Additionally, we explored interactions of Tβ4 with PAI-1. Treatment with Ac-SDKP significantly decreased fibrosis in both wild-type and PAI-1 knockout mice, as observed by decreased collagen and fibronectin deposition, fewer myofibroblasts and macrophages, and suppressed profibrotic factors. In contrast, Tβ4 plus a prolyl oligopeptidase inhibitor significantly increased fibrosis in wild-type mice. Tβ4 alone also promoted repair and reduced late fibrosis in wild-type mice. Importantly, both profibrotic effects of Tβ4 plus the prolyl oligopeptidase inhibitor, and late reparative effects of Tβ4 alone, were absent in PAI-1 knockout mice. Thus, Tβ4 combined with prolyl oligopeptidase inhibition is consistently profibrotic, but by itself has antifibrotic effects in late-stage fibrosis, while Ac-SDKP has consistent antifibrotic effects in both early and late stages of kidney injury. These effects of Tβ4 are dependent on PAI-1.Kidney International advance online publication, 5 June 2013; doi:10.1038/ki.2013.209.
    Kidney International 06/2013; 84(6). DOI:10.1038/ki.2013.209
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    ABSTRACT: Myocardial matrix turnover involves a dynamic balance between collagen synthesis and degradation, which is regulated by matrix metalloproteinases (MMPs). N-acetyl-Ser-Asp-Lys-Pro (Ac-SDKP) is a small peptide that inhibits cardiac inflammation and fibrosis. However, its role in MMP regulation is not known. Thus, we hypothesized that Ac-SDKP promotes MMP activation in cardiac fibroblasts and decreases collagen deposition via this mechanism. To that end, we tested the effects of Ac-SDKP on interleukin-1β (IL-1β; 5 ng/ml)-stimulated adult rat cardiac fibroblasts. We measured total collagenase activity, MMP-2, MMP-9, and MMP-13 expressions, and activity along with their inhibitors, tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2. In order to examine the effects of Ac-SDKP on the signaling pathway that controls MMP transcription, we also measured nuclear factor-κB (NFκB) and p42/44 mitogen-activated protein kinase (MAPK) activation. Ac-SDKP did not alter collagenase or gelatinase activity in cardiac fibroblasts under basal conditions, but blunted the IL-1β-induced increase in total collagenase activity. Similarly, Ac-SDKP normalized the IL-1β-mediated increase in MMP-2 and MMP-9 activities and MMP-13 expression. Inhibition of MMPs by Ac-SDKP was associated with increased TIMP-1 and TIMP-2 expressions. Collagen production was not affected by Ac-SDKP, IL-1β, or a combination of both agents. Ac-SDKP blocked IL-1β-induced p42/44 phosphorylation and NFκB activation in cardiac fibroblasts. We concluded that the Ac-SDKP-inhibited collagenase expression and activation was associated with increased expression of TIMP-1 and TIMP-2. These pharmacological effects of Ac-SDKP may be linked to the inhibition of MAPK and NFκB pathway.
    Pflügers Archiv - European Journal of Physiology 05/2013; 465(10). DOI:10.1007/s00424-013-1262-8
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    ABSTRACT: Tubuloglomerular feedback (TGF) is a mechanism that senses NaCl in the macula densa (MD) and causes constriction of the afferent arteriole. CO, either endogenous or exogenous, inhibits TGF at least in part via cGMP. We hypothesize that CO in the MD, acting via both cGMP-dependent and -independent mechanisms, attenuates TGF by acting downstream from depolarization and calcium entry into the MD cells. In vitro, microdissected rabbit afferent arterioles and their MD were simultaneously perfused and TGF was measured as the decrease in afferent arteriole diameter. MD depolarization was induced with ionophores, while adding the CO-releasing molecule-3 to the MD perfusate at nontoxic concentrations. CO-releasing molecule-3 blunted depolarization-induced TGF at 50 μmol/L, from 3.6±0.4 to 2.5±0.4 µm (P<0.01), and abolished it at 100 μmol/L, to 0.1±0.1 μm (P<0.001; n=6). When cGMP generation was blocked by guanylyl cyclase inhibitor LY83583 added to the MD, CO-releasing molecule-3 no longer affected depolarization-induced TGF at 50 μmol/L (2.9±0.4 versus 3.0±0.4 µm) but partially inhibited TGF at 100 μmol/L (to 1.3±0.2 μm; P<0.05; n=9). Experiments using eicosatetraynoic acid and indomethacin suggest arachidonic acid metabolites do not mediate the cGMP-independent effect of CO. We then added the calcium ionophore A23187 to the MD, which caused TGF (4.1±0.6 μmol/L); A23187-induced TGF was inhibited by CO-releasing molecule-3 at 50 μmol/L (1.9±0.6 μmol/L; P<0.01) and 100 μmol/L (0.2±0.5 μmol/L; P<0.001; n=6). We conclude that CO inhibits TGF acting downstream from depolarization and calcium entry, acting via cGMP at low concentrations, but additional mechanisms of action may be involved at higher concentrations.
    Hypertension 05/2013; 62(1). DOI:10.1161/HYPERTENSIONAHA.113.01164
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    ABSTRACT: N-Acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) inhibits endothelin-1 (ET-1)-induced activation of p44/42 mitogen-activated protein kinase (p44/42 MAPK) and collagen production in cultured rat cardiac fibroblasts (RCFs). However, we do not know whether its inhibitory effect on p44/42 MAPK is due to the altered activity of protein tyrosine phosphatases (PTPs), which in turn downregulate the p44/42 MAPK signaling pathway. The activity of Src homology 2-containing protein tyrosine phosphatase-2 (SHP-2) is downregulated by ET-1 in RCFs; thus, we hypothesized that Ac-SDKP inhibits ET-1-stimulated collagen production in part by preserving SHP-2 activity and thereby inhibiting p44/42 MAPK phosphorylation. When we stimulated RCFs with ET-1 in the presence or absence of Ac-SDKP, we found that (a) PTP activity was reduced by ET-1 and (b) this effect was counteracted by Ac-SDKP in a dose-dependent fashion. Next, we extracted SHP-2 from RCF lysates by immunoprecipitation and determined that (a) ET-1 inhibited SHP-2 by 40 % and (b) this effect was prevented by Ac-SDKP. However, Ac-SDKP failed to inhibit ET-1-induced p44/42 MAPK phosphorylation in RCFs treated with SHP-2 short hairpin RNA (shRNA); in contrast, in cells transfected with control shRNA, Ac-SDKP's inhibitory effect on ET-1-induced p44/42 MAPK activation remained intact. Moreover, the inhibitory effect of Ac-SDKP on ET-1-stimulated collagen production was blunted in cells treated with the SHP-1/2 inhibitor NSC-87877. Thus, we concluded that the inhibitory effect of Ac-SDKP on ET-1-stimulated collagen production by RCFs is mediated in part by preserving SHP-2 activity and thereby preventing p44/42 MAPK activation. Ac-SDKP or its analogs could represent a new therapeutic tool to treat fibrotic diseases in the cardiovascular system.
    Pflügers Archiv - European Journal of Physiology 09/2012; 464(4):415-23. DOI:10.1007/s00424-012-1150-7
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    ABSTRACT: Rationale: Myocarditis is commonly associated with cardiotropic infections and has been linked to development of autoimmunity. N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) is a naturally occurring tetrapeptide that prevents inflammation and fibrosis in hypertension and other cardiovascular diseases; however, its effect on autoimmune-mediated cardiac diseases remains unknown. We studied the effects of Ac-SDKP in experimental autoimmune myocarditis (EAM), a model of T cell-mediated autoimmune disease. Objective: To test the hypothesis that Ac-SDKP prevents autoimmune myocardial injury by modulating the immune responses. Methods and Results: Lewis rats were immunized with porcine cardiac myosin and treated with Ac-SDKP or vehicle. In EAM, Ac-SDKP prevented both systolic and diastolic cardiac dysfunction, remodeling as shown by hypertrophy and fibrosis, and cell-mediated immune responses without affecting myosin-specific autoantibodies or antigen-specific T cell responses. In addition, Ac-SDKP reduced cardiac infiltration by macrophages, dendritic cells, and T cells, pro-inflammatory cytokines (IL-1α, TNF-α, IL-2, IL-17) and chemokines (CINC-1, IP-10), cell adhesion molecules (ICAM-1, L-selectin) and matrix metalloproteinases (MMP). Conclusions: Ac-SDKP prevents autoimmune cardiac dysfunction and remodeling without reducing the production of autoantibodies or T cell responses to cardiac myosin. The protective effects of Ac-SDKP in autoimmune myocardial injury are most likely mediated by inhibition of a) innate and adaptive immune cell infiltration and b) expression of pro-inflammatory mediators such as cytokines, chemokines, adhesion molecules and MMPs.
    AJP Heart and Circulatory Physiology 08/2012; DOI:10.1152/ajpheart.00300.2011
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    ABSTRACT: AT2Rs [AngII (angiotensin II) type 2 receptors] contribute to the cardioprotective effects of angiotensin II receptor blockers, possibly via kinins acting on the B1R (B1 receptor) and B2R (B2 receptor). Recent studies have shown that a lack of B2R up-regulates B1R and AT2R; however, the pathophysiological relevance of such an event remains unclear. We hypothesized that up-regulation of AT2R and B1R compensates for the loss of B2R. Blockade of AT2R and/or B1R worsens cardiac remodelling and dysfunction following MI (myocardial infarction) in B2R-/- (B2-receptor-knockout mice). B2R-/- mice and WT (wild-type) controls were subjected to sham MI or MI and treated for 4 weeks with (i) vehicle, (ii) a B1R-ant (B1R antagonist; 300 μg/kg of body weight per day), (iii) an AT2R-ant [AT2 receptor antagonist (PD123319); 20 mg/kg of body weight per day], or (iv) B1R-ant+AT2R-ant. B2R-/- mice had a greater MCSA (myocyte cross-sectional area) and ICF (interstitial collagen fraction) at baseline and after MI compared with WT controls. Cardiac function and increase in macrophage infiltration, TGFβ1 (transforming growth factor β1) expression and ERK1/2 (extracellular-signal-regulated kinase 1/2) phosphorylation post-MI were similar in both strains. Blockade of AT2R or B1R worsened cardiac remodelling, hypertrophy and dysfunction associated with increased inflammation and ERK1/2 phosphorylation and decreased NO excretion in B2R-/-mice, which were exacerbated by dual blockade of B1R and AT2R. No such effects were seen in WT mice. Our results suggest that, in the absence of B2R, both B1R and AT2R play important compensatory roles in preventing deterioration of cardiac function and remodelling post-MI possibly via suppression of inflammation, TGFβ1 and ERK1/2 signalling.
    Clinical Science 07/2012; 124(2):87-96. DOI:10.1042/CS20120341
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    ABSTRACT: ANG II type 2 receptors (AT(2)R) elicit cardioprotective effects in part by stimulating the release of kinins; however, the mechanism(s) responsible have not been fully explored. We demonstrated previously that overexpression of AT(2)R increased expression of prolylcarboxypeptidase (PRCP; a plasma prekallikrein activator) and release of bradykinin by mouse coronary artery endothelial cells (ECs). In the present study we hypothesized that the AT(2)R-stimulated increase in PRCP is mediated by the tyrosine phosphatase SHP-1, which in turn activates the PRCP-dependent prekallikrein-kallikrein pathway and releases bradykinin. We found that activation of AT(2)R using the specific agonist CGP42112A increased SHP-1 activity in ECs, which was blocked by the AT(2)R antagonist PD123319. Activation of AT(2)R also enhanced conversion of plasma prekallikrein to kallikrein, and this effect was blunted by a small interfering RNA (siRNA) to SHP-1 and abolished by the tyrosine phosphatase inhibitor sodium orthovanadate. Treating cells with a siRNA to PRCP also blunted AT(2)R-stimulated prekallikrein activation and bradykinin release. Furthermore, blocking plasma kallikrein with soybean trypsin inhibitor (SBTI) abolished AT(2)R-stimulated bradykinin release. These findings support our hypothesis that stimulation of AT(2)R activates a PRCP-dependent plasma prekallikrein pathway, releasing bradykinin. Activation of SHP-1 may also play an important role in AT(2)R-induced PRCP activation.
    AJP Heart and Circulatory Physiology 04/2012; 302(12):H2553-9. DOI:10.1152/ajpheart.01157.2011
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    ABSTRACT: In response to a homeostatic threat circulating renin increases by increasing the number of cells expressing renin by dedifferentiation and re-expression of renin in arteriolar smooth muscle cells (aSMCs) that descended from cells that expressed renin in early life. However, the mechanisms that govern the maintenance and reacquisition of the renin phenotype are not well understood. The cAMP pathway is important for renin synthesis and release: the transcriptional effects are mediated by binding of cAMP responsive element binding protein with its co-activators, CBP and p300, to the cAMP response element in the renin promoter. We have shown previously that mice with conditional deletion of CBP and p300 (cKO) in renin cells had severely reduced renin expression in adult life. In this study we investigated when the loss of renin-expressing cells in the cKO occurred and found that the loss of renin expression becomes evident after differentiation of the kidney is completed during postnatal life. To determine whether CBP/p300 is necessary for re-expression of renin we subjected cKO mice to low sodium diet + captopril to induce retransformation of aSMCs to the renin phenotype. The cKO mice did not increase circulating renin, their renin mRNA and protein expression were greatly diminished compared with controls, and only a few aSMCs re-expressed renin. These studies underline the crucial importance of the CREB/CBP/p300 complex for the ability of renin cells to retain their cellular memory and regain renin expression, a fundamental survival mechanism, in response to a threat to homeostasis.
    AJP Heart and Circulatory Physiology 04/2012; 302(12):H2545-52. DOI:10.1152/ajpheart.00782.2011
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    ABSTRACT: Carbon monoxide (CO) is a physiological messenger with diverse functions in the kidney, including controlling afferent arteriole tone both directly and via tubuloglomerular feedback (TGF). We have reported that CO attenuates TGF, but the mechanisms underlying this effect remain unknown. We hypothesized that CO, acting via cGMP, cGMP-dependent protein kinase, and cGMP-stimulated phosphodiesterase 2, reduces cAMP in the macula densa, leading to TGF attenuation. In vitro, microdissected rabbit afferent arterioles and their attached macula densa were simultaneously perfused. TGF was measured as the decrease in afferent arteriole diameter elicited by switching macula densa NaCl from 10 to 80 mmol/L. Adding a CO-releasing molecule (CORM-3, 5 × 10(-5) mol/L) to the macula densa blunted TGF from 3.3 ± 0.3 to 2.0 ± 0.3 μm (P<0.001). The guanylate cyclase inhibitor LY-83583 (10(-6) mol/L) enhanced TGF (5.8 ± 0.6 μm; P<0.001 versus control) and prevented the effect of CORM-3 on TGF (LY-83583+CORM-3, 5.5 ± 0.3 μm). Similarly, the cGMP-dependent protein kinase inhibitor KT-5823 (2 × 10(-6) mol/L) enhanced TGF and prevented the effect of CORM-3 on TGF (KT-5823, 6.0 ± 0.7 μm; KT-5823+CORM-3, 5.9 ± 0.8 μm). However, the phosphodiesterase 2 inhibitor BAY-60-7550 (10(-6) mol/L) did not prevent the effect of CORM-3 on TGF (BAY-60-7550, 4.07 ± 0.31 μm; BAY-60-7550+CORM-3, 1.84 ± 0.31 μm; P<0.001). Finally, the degradation-resistant cAMP analog dibutyryl-cAMP (10(-3) mol/L) prevented the attenuation of TGF by CORM-3 (dibutyryl-cAMP, 4.6 ± 0.5 μm; dibutyryl-cAMP+CORM-3, 5.0 ± 0.6 μm). We conclude that CO attenuates TGF by reducing cAMP via a cGMP-dependent pathway mediated by cGMP-dependent protein kinase rather than phosphodiesterase 2. Our results will lead to a better understanding of the mechanisms that control the renal microcirculation.
    Hypertension 04/2012; 59(6):1139-44. DOI:10.1161/HYPERTENSIONAHA.112.192120

Publication Stats

10k Citations
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  • 1974–2014
    • Henry Ford Hospital
      • • Department of Internal Medicine
      • • Division of Hypertension and Vascular Research
      Detroit, Michigan, United States
  • 2013
    • University of Buenos Aires
      • Institute of Cardiovascular Physiopathology (INFICA)
      Buenos Aires, Buenos Aires F.D., Argentina
  • 2008
    • University of Mississippi Medical Center
      • Department of Physiology and Biophysics
      Jackson, MS, United States
  • 2002–2008
    • Henry Ford Health System
      • • Department of Internal Medicine
      • • Department of Radiation Oncology
      • • Hypertension and Vascular Research Division
      Detroit, Michigan, United States
  • 2006
    • Wayne State University
      • Department of Internal Medicine
      Detroit, MI, United States
  • 2005
    • University of Texas at Dallas
      • Biochemistry
      Richardson, Texas, United States
  • 2004
    • Government of the People's Republic of China
      Peping, Beijing, China
    • University of Groningen
      Groningen, Groningen, Netherlands
  • 2003
    • The Ohio State University
      Columbus, Ohio, United States
  • 1998–2001
    • Case Western Reserve University
      Cleveland, Ohio, United States
  • 2000
    • Wake Forest School of Medicine
      • Department of Anesthesiology
      Winston-Salem, NC, United States
  • 1995
    • Loyola University Medical Center
      Maywood, Illinois, United States
  • 1994
    • National University of Cordoba, Argentina
      Córdoba, Cordoba, Argentina
  • 1983–1989
    • University of Oslo
      • Department of Biochemistry
      Kristiania (historical), Oslo County, Norway
  • 1988
    • Medical College of Wisconsin
      • Department of Physiology
      Milwaukee, WI, United States
  • 1965
    • National University of Cuyo
      • Facultad de Ciencias Médicas
      Мендоса, Mendoza, Argentina