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Hypoxanthine Induces Signs of Bladder Aging With Voiding Dysfunction and Lower Urinary Tract Remodeling. J Gerontol A Biol Sci Med Sci 2024; 79:glad171. [PMID: 37463319 PMCID: PMC11083631 DOI: 10.1093/gerona/glad171] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Indexed: 07/20/2023] Open
Abstract
BACKGROUND Lower urinary tract syndrome (LUTS) is a group of urinary tract symptoms and signs that can include urinary incontinence. Advancing age is a major risk factor for LUTS; however, the underlying biochemical mechanisms of age-related LUTS remain unknown. Hypoxanthine (HX) is a purine metabolite associated with generation of tissue-damaging reactive oxygen species (ROS). This study tested the hypothesis that exposure of the adult bladder to HX-ROS over time damages key LUT elements, mimicking qualitatively some of the changes observed with aging. METHODS Adult 3-month-old female Fischer 344 rats were treated with vehicle or HX (10 mg/kg/day; 3 weeks) administered in drinking water. Targeted purine metabolomics and molecular approaches were used to assess purine metabolites and biomarkers for oxidative stress and cellular damage. Biomechanical approaches assessed LUT structure and measurements of LUT function (using custom-metabolic cages and cystometry) were also employed. RESULTS HX exposure increased biomarkers indicative of oxidative stress, pathophysiological ROS production, and depletion of cellular energy with declines in NAD+ levels. Moreover, HX treatment caused bladder remodeling and decreased the intercontraction interval and leak point pressure (surrogate measure to assess stress urinary incontinence). CONCLUSIONS These studies provide evidence that in adult rats chronic exposure to HX causes changes in voiding behavior and in bladder structure resembling alterations observed with aging. These results suggest that increased levels of uro-damaging HX were associated with ROS/oxidative stress-associated cellular damage, which may be central to age-associated development of LUTS, opening up potential opportunities for geroscience-guided interventions.
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Purine nucleoside phosphorylase inhibition is an effective approach for the treatment of chemical hemorrhagic cystitis. JCI Insight 2024; 9:e176103. [PMID: 38271096 PMCID: PMC10972598 DOI: 10.1172/jci.insight.176103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 01/22/2024] [Indexed: 01/27/2024] Open
Abstract
Hemorrhagic cystitis may be induced by infection, radiation therapy, or medications or may be idiopathic. Along with hemorrhagic features, symptoms include urinary urgency and frequency, dysuria (painful urination), and visceral pain. Cystitis-induced visceral pain is one of the most challenging types of pain to treat, and an effective treatment would address a major unmet medical need. We assessed the efficacy of a purine nucleoside phosphorylase inhibitor, 8-aminoguanine (8-AG), for the treatment of hemorrhagic/ulcerative cystitis. Lower urinary tract (LUT) function and structure were assessed in adult Sprague-Dawley rats, treated chronically with cyclophosphamide (CYP; sacrificed day 8) and randomized to daily oral treatment with 8-AG (begun 14 days prior to CYP induction) or its vehicle. CYP-treated rats exhibited multiple abnormalities, including increased urinary frequency and neural mechanosensitivity, reduced bladder levels of inosine, urothelial inflammation/damage, and activation of spinal cord microglia, which is associated with pain hypersensitivity. 8-AG treatment of CYP-treated rats normalized all observed histological, structural, biochemical, and physiological abnormalities. In cystitis 8-AG improved function and reduced both pain and inflammation likely by increasing inosine, a tissue-protective purine metabolite. These findings demonstrate that 8-AG has translational potential for reducing pain and preventing bladder damage in cystitis-associated LUT dysfunctions.
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Assessment of ATP Metabolism to Adenosine by Ecto-Nucleotidases Carried by Tumor-Derived Small Extracellular Vesicles. RESEARCH SQUARE 2024:rs.3.rs-3876953. [PMID: 38343828 PMCID: PMC10854312 DOI: 10.21203/rs.3.rs-3876953/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
Background Immunosuppression is a hallmark of cancer progression. Tumor-derived small extracellular vesicles (sEV), also known as TEX, produce adenosine (ADO) and can mediate tumor-induced immunosuppression. Methods Here, the ATP pathway of ADO production (ATP◊ADP◊AMP◊ADO) by ecto-nucleotidases carried in sEV was evaluated by a novel method using N6-etheno-ATP (eATP) and N6-etheno-AMP (eAMP) as substrates. The "downstream" N6-etheno-purines (ePurines) were measured by high performance liquid chromatography with fluorescence detection (HPLC-FL). Results Human melanoma cell-derived TEX (MTEX) metabolized eATP to N6-etheno-ADP (eADP), eAMP and N6-etheno-Adenosine (eADO) more robustly than control keratinocyte cell-derived sEV (CEX); due to accelerated conversion of eATP to eADP and eADP to eAMP MTEX and CEX similarly metabolized eAMP to eADO. Blocking of the ATP pathway with the selective CD39 inhibitor ARL67156 or pan ecto-nucleotidase inhibitor POM-1 normalized the ATP pathway but neither inhibitor completely abolished it. In contrast, inhibition of CD73 by PSB12379 or AMPCP abolished eADO formation in both MTEX and CEX, suggesting that targeting CD73 is the preferred approach to eliminating ADO produced by sEV. Conclusions The noninvasive, sensitive, and specific assay assessing ePurine metabolism ± ecto-nucleotidase inhibitors in TEX enables the personalized identification of the ecto-nucleotidase primarily involved in ADO production in patients with cancer. The assay could guide precision medicine by determining which purine is the preferred target for inhibitory therapeutic interventions.
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8-Aminopurines in the Cardiovascular and Renal Systems and Beyond. Hypertension 2023; 80:2265-2279. [PMID: 37503660 PMCID: PMC10592300 DOI: 10.1161/hypertensionaha.123.20582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Screening of compounds comprising 8-substituted guanine revealed that 8-aminoguanosine and 8-aminoguanine cause diuresis/natriuresis/glucosuria, yet decrease potassium excretion. Subsequent investigations demonstrated that 8-aminoguanosine's effects are mediated by its metabolite 8-aminoguanine. The mechanism by which 8-aminoguanine causes diuresis/natriuresis/glucosuria involves inhibition of PNPase (purine nucleoside phosphorylase), which increases renal interstitial inosine levels. Additional evidence suggests that inosine, via indirect or direct adenosine A2B receptor activation, increases renal medullary blood flow which enhances renal excretory function. Likely, 8-aminoguanine has pleiotropic actions that also alter renal excretory function. Indeed, the antikaliuretic effects of 8-aminoguanine are independent of PNPase inhibition. 8-Aminoguanine is an endogenous molecule; nitrosative stress leads to production of biomolecules containing 8-nitroguanine moieties. Degradation of these biomolecules releases 8-nitroguanosine and 8-nitro-2'-deoxyguanosine which are converted to 8-aminoguanine. Also, guanosine and guanine per se may contribute to 8-aminoguanine formation. 8-Aminoinosine, 8-aminohypoxanthine, and 8-aminoxanthine likewise induce diuresis/natriuresis/glucosuria, yet do not reduce potassium excretion. Thus, there are several pharmacologically active 8-aminopurines with nuanced effects on renal excretory function. Chronic treatment with 8-aminoguanine attenuates hypertension in deoxycorticosterone/salt rats, prevents strokes, and increases lifespan in Dahl salt-sensitive rats on a high salt diet and attenuates the metabolic syndrome in rats; 8-aminoguanosine retards progression of pulmonary hypertension in rats and anemia and organ damage in sickle cell mice. 8-Aminoguanine reverses age-associated lower urinary tract dysfunction and retinal degeneration. 8-Aminopurines represent a new class of agents (and potentially endogenous factors) that have beneficial effects on the cardiovascular system and kidneys and may turn back the clock in age-associated diseases.
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8-Aminoguanine and Its Actions on Renal Excretory Function. Hypertension 2023; 80:981-994. [PMID: 36802842 PMCID: PMC10112938 DOI: 10.1161/hypertensionaha.122.20760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
BACKGROUND The endogenous purine 8-aminoguanine induces diuresis/natriuresis/glucosuria by inhibiting PNPase (purine nucleoside phosphorylase); however, mechanistic details are unknown. METHODS Here, we further explored in rats 8-aminoguanine's effects on renal excretory function by combining studies using intravenous 8-aminoguanine, intrarenal artery infusions of PNPase substrates (inosine and guanosine), renal microdialysis, mass spectrometry, selective adenosine receptor ligands, adenosine receptor knockout rats, laser doppler blood flow analysis, cultured renal microvascular smooth muscle cells, HEK293 cells expressing A2B receptors and homogeneous time resolved fluorescence assay for adenylyl cyclase activity. RESULTS Intravenous 8-aminoguanine caused diuresis/natriuresis/glucosuria and increased renal microdialysate levels of inosine and guanosine. Intrarenal inosine, but not guanosine, exerted diuretic/natriuretic/glucosuric effects. In 8-aminoguanine-pretreated rats, intrarenal inosine did not induce additional diuresis/natriuresis/glucosuria. 8-Aminoguanine did not induce diuresis/natriuresis/glucosuria in A2B-receptor knockout rats, yet did so in A1- and A2A-receptor knockout rats. Inosine's effects on renal excretory function were abolished in A2B knockout rats. Intrarenal BAY 60-6583 (A2B agonist) induced diuresis/natriuresis/glucosuria and increased medullary blood flow. 8-Aminoguanine increased medullary blood flow, a response blocked by pharmacological inhibition of A2B, but not A2A, receptors. In HEK293 cells expressing A2B receptors, inosine activated adenylyl cyclase, and this was abolished by MRS 1754 (A2B antagonist). In renal microvascular smooth muscle cells, 8-aminoguanine and forodesine (PNPase inhibitor) increased inosine and 3',5'-cAMP; however, in cells from A2B knockout rats, 8-aminoguanine and forodesine did not augment 3',5'-cAMP yet increased inosine. CONCLUSIONS 8-Aminoguanine induces diuresis/natriuresis/glucosuria by increasing renal interstitial levels of inosine which, via A2B receptor activation, increases renal excretory function, perhaps in part by increasing medullary blood flow.
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Purine nucleoside phosphorylase as a target to treat age-associated lower urinary tract dysfunction. Nat Rev Urol 2022; 19:681-687. [PMID: 36071153 PMCID: PMC9842101 DOI: 10.1038/s41585-022-00642-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/01/2022] [Indexed: 01/18/2023]
Abstract
The lower urinary tract (LUT), including the bladder, urethra and external striated muscle, becomes dysfunctional with age; consequently, many older individuals suffer from lower urinary tract disorders (LUTDs). By compromising urine storage and voiding, LUTDs degrade quality of life for millions of individuals worldwide. Treatments for LUTDs have been disappointing, frustrating both patients and their physicians; however, emerging evidence suggests that partial inhibition of the enzyme purine nucleoside phosphorylase (PNPase) with 8-aminoguanine (an endogenous PNPase inhibitor that moderately reduces PNPase activity) reverses age-associated defects in the LUT and restores the LUT to that of a younger state. Thus, 8-aminoguanine improves LUT biochemistry, structure and function by rebalancing the LUT purine metabolome, making 8-aminoguanine a novel potential treatment for LUTDs.
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Suppressed renoprotective purines in COVID-19 patients with acute kidney injury. Sci Rep 2022; 12:17353. [PMID: 36253495 PMCID: PMC9574168 DOI: 10.1038/s41598-022-22349-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 10/13/2022] [Indexed: 01/10/2023] Open
Abstract
Acute kidney injury (AKI) is common in patients hospitalized for COVID-19, complicating their clinical course and contributing to worse outcomes. Animal studies show that adenosine, inosine and guanosine protect the kidney against some types of AKI. However, until now there was no evidence in patients supporting the possibility that abnormally low kidney levels of adenosine, inosine and guanosine contribute to AKI. Here, we addressed the question as to whether these renoprotective purines are altered in the urine of COVID-19 patients with AKI. Purines were measured by employing ultra-high-performance liquid chromatography-tandem mass spectrometry with stable-isotope-labeled internal standards for each purine of interest. Compared with COVID-19 patients without AKI (n = 23), COVID-19 patients with AKI (n = 20) had significantly lower urine levels of adenosine (P < 0.0001), inosine (P = 0.0008), and guanosine (P = 0.0008) (medians reduced by 85%, 48% and 61%, respectively) and lower levels (P = 0.0003; median reduced by 67%) of the 2nd messenger for A2A and A2B adenosine receptors, i.e., 3',5'-cAMP. Moreover, in COVID-19 patients with AKI, urine levels of 8-aminoguanine (endogenous inhibitor of inosine and guanosine metabolism) were nearly abolished (P < 0.0001). In contrast, the "upstream" precursors of renoprotective purines, namely 5'-AMP and 5'-GMP, were not significantly altered in COVID-19 patients with AKI, suggesting defective conversion of these precursors by CD73 (converts 5'-AMP to adenosine and 5'-GMP to guanosine). These findings imply that an imbalance in renoprotective purines may contribute to AKI in COVID-19 patients and that pharmacotherapy targeted to restore levels of renoprotective purines may attenuate the risk of AKI in susceptible patients with COVID-19.
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8-Aminoinosine and 8-Aminohypoxanthine Inhibit Purine Nucleoside Phosphorylase and Exert Diuretic and Natriuretic Activity. J Pharmacol Exp Ther 2022; 382:135-148. [PMID: 35609923 PMCID: PMC9639651 DOI: 10.1124/jpet.122.001221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Accepted: 05/12/2022] [Indexed: 01/01/2023] Open
Abstract
8-Aminoguanine and 8-aminoguanosine (via metabolism to 8-aminoguanine) are endogenous 8-aminopurines that induce diuresis, natriuresis, and glucosuria by inhibiting purine nucleoside phosphorylase (PNPase); moreover, both 8-aminopurines cause antikaliuresis by other mechanisms. Because 8-aminoinosine and 8-aminohypoxanthine are structurally similar to 8-aminoguanosine and 8-aminoguanine, respectively, we sought to define their renal excretory effects. First, we compared the ability of 8-aminoguanine, 8-aminohypoxanthine, and 8-aminoinosine to inhibit recombinant PNPase. These compounds inhibited PNPase with a potency order of 8-aminoguanine > 8-aminohypoxanthine = 8-aminoinosine. Additional studies showed that 8-aminoinosine is a competitive substrate that is metabolized to a competitive PNPase inhibitor, namely 8-aminohypoxanthine. Administration of each 8-aminopurine (33.5 µmol/kg) reduced the guanine-to-guanosine and hypoxanthine-to-inosine ratios in urine, a finding confirming their ability to inhibit PNPase in vivo. All three 8-aminopurines induced diuresis, natriuresis, and glucosuria; however, the glucosuric effects of 8-aminohypoxanthine and 8-aminoinosine were less pronounced than those of 8-aminoguanine. Neither 8-aminohypoxanthine nor 8-aminoinosine altered potassium excretion, whereas 8-aminoguanine caused antikaliuresis. In vivo administration of 8-aminoinosine increased 8-aminohypoxanthine excretion, indicating that 8-aminohypoxanthine mediates, in part, the effects of 8-aminoinosine. Finally, 8-aminohypoxanthine was metabolized to 8-aminoxanthine by xanthine oxidase. Using ultraperformance liquid chromatography-tandem mass spectrometry, we identified 8-aminoinosine as an endogenous 8-aminopurine. In conclusion, 8-aminopurines have useful pharmacological profiles. To induce diuresis, natriuresis, glucosuria, and antikaliuresis, 8-aminoguanine (or its prodrug 8-aminoguanosine) would be preferred. If only diuresis and natriuresis, without marked glucosuria or antikaliuresis, is desired, 8-aminohypoxanthine or 8-aminoinosine might be useful. Finally, here we report the in vivo existence of another pharmacologically active 8-aminopurine, namely 8-aminoinosine. SIGNIFICANCE STATEMENT: Here, we report that a family of 8-aminopurines affects renal excretory function: effects that may be useful for treating multiple diseases including hypertension, heart failure, and chronic kidney disease. For diuresis and natriuresis accompanied by glucosuria and antikaliuresis, 8-aminoguanine (or its prodrug 8-aminoguanosine) would be useful; if only diuresis and natriuresis is called for, 8-aminohypoxanthine or 8-aminoinosine would be useful. Previously, we identified 8-aminoguanine and 8-aminoguanosine as endogenous 8-aminopurines; here, we extend the family of endogenous 8-aminopurines to include 8-aminoinosine.
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Cargo and Functional Profile of Saliva-Derived Exosomes Reveal Biomarkers Specific for Head and Neck Cancer. Front Med (Lausanne) 2022; 9:904295. [PMID: 35899209 PMCID: PMC9309685 DOI: 10.3389/fmed.2022.904295] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 06/20/2022] [Indexed: 12/20/2022] Open
Abstract
Background Exosomes contribute to immunosuppression in head and neck squamous cell carcinoma (HNSCC), a tumor entity which lacks specific tumor biomarkers. Plasma-derived exosomes from HNSCC patients correlate with clinical parameters and have potential as liquid biopsy. Here, we investigate the cargo and functional profile of saliva-derived exosomes from HNSCC patients and their potential as non-invasive biomarkers for disease detection and immunomodulation. Methods Exosomes were isolated from saliva of HNSCC patients (n = 21) and healthy donors (HD, n = 12) by differential ultracentrifugation. Surface values of immune checkpoints and tumor associated antigens on saliva-derived exosomes were analyzed by bead-based flow cytometry using CD63 capture. Upon co-incubation with saliva-derived exosomes, activity and proliferation of T cells were assessed by flow cytometry (CD69 expression, CFSE assay). Adenosine levels were measured by mass spectrometry after incubation of saliva-derived exosomes with exogenous ATP. miRNA profiling of saliva-derived exosomes was performed using the nCounter® SPRINT system. Results Saliva-derived, CD63-captured exosomes from HNSCC patients carried high amounts of CD44v3, PDL1 and CD39. Compared to plasma, saliva was rich in tumor-derived, CD44v3+ exosomes and poor in hematopoietic cell-derived, CD45+ exosomes. CD8+ T cell activity was attenuated by saliva-derived exosomes from HNSCC patients, while proliferation of CD4+ T cells was not affected. Further, saliva-derived exosomes produced high levels of immunosuppressive adenosine. 62 HD- and 31 HNSCC-exclusive miRNAs were identified. Samples were grouped in "Healthy" and "Cancer" based on their saliva-derived exosomal miRNA profile, which was further found to be involved in RAS/MAPK, NF-κB complex, Smad2/3, and IFN-α signaling. Conclusions Saliva-derived exosomes from HNSCC patients were enriched in tumor-derived exosomes whose cargo and functional profile reflected an immunosuppressive TME. Surface values of CD44v3, PDL1 and CD39 on CD63-captured exosomes, adenosine production and the miRNA cargo of saliva-derived exosomes emerged as discriminators of disease and emphasized their potential as liquid biomarkers specific for HNSCC.
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Angiotensin II augments renal vascular smooth muscle soluble GC expression via an AT 1 receptor-forkhead box subclass O transcription factor signalling axis. Br J Pharmacol 2022; 179:2490-2504. [PMID: 33963547 PMCID: PMC8883839 DOI: 10.1111/bph.15522] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 04/18/2021] [Accepted: 04/23/2021] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE Reduced renal blood flow triggers activation of the renin-angiotensin-aldosterone system (RAAS) leading to renovascular hypertension. Renal vascular smooth muscle expression of the NO receptor, soluble GC (sGC), modulates the vasodilator response needed to control renal vascular tone and blood flow. Here, we tested if angiotensin II (Ang II) affects sGC expression via an AT1 receptor-forkhead box subclass O (FoxO) transcription factor dependent mechanism. EXPERIMENTAL APPROACH Using a murine two-kidney-one-clip (2K1C) renovascular hypertension model, we measured renal artery vasodilatory function and sGC expression. Additionally, we conducted cell culture studies using rat renal pre-glomerular smooth muscle cells (RPGSMCs) to test the in vitro mechanistic effects of Ang II treatment on sGC expression and downstream function. KEY RESULTS Contralateral, unclipped renal arteries in 2K1C mice showed increased NO-dependent vasorelaxation compared to sham control mice. Immunofluorescence studies revealed increased sGC protein expression in 2K1C contralateral renal arteries over sham controls. RPGSMCs treated with Ang II caused a significant up-regulation of sGC mRNA and protein expression as well as downstream sGC-dependent signalling. Ang II signalling effects on sGC expression occurred through an AT1 receptor and FoxO transcription factor-dependent mechanism at both the mRNA and protein expression levels. CONCLUSION AND IMPLICATIONS Renal artery smooth muscle, in vivo and in vitro, up-regulates expression of sGC following RAAS activity. In both cases, up-regulation of sGC leads to increased downstream cGMP signalling, suggesting a previously unrecognized protective mechanism to improve renal blood flow in the uninjured contralateral renal artery. LINKED ARTICLES This article is part of a themed issue on cGMP Signalling in Cell Growth and Survival. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v179.11/issuetoc.
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Biochemical Pathways of 8-Aminoguanine Production In Sprague-Dawley and Dahl Salt-Sensitive Rats. Biochem Pharmacol 2022; 201:115076. [PMID: 35551915 DOI: 10.1016/j.bcp.2022.115076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 04/30/2022] [Accepted: 05/03/2022] [Indexed: 11/02/2022]
Abstract
BACKGROUND 8-Aminoguanine exerts natriuretic and antihypertensive activity. Whether and how "free" 8-aminoguanine exists in vivo is unclear. Because 8-nitroguanosine is naturally occurring, we tested the hypothesis that 8-aminoguanine can arise from: pathway 1, 8-nitroguanosine→8-aminoguanosine→8-aminoguanine; and pathway 2, 8-nitroguanosine→8-nitroguanine→8-aminoguanine. METHODS 8-Aminoguanine biosynthesis was explored in rats using renal microdialysis, mass spectrometry and enzyme kinetics. RESULTS In Sprague-Dawley rats, 8-nitroguanosine infusions increased kidney levels of 8-nitroguanine, 8-aminoguanosine and 8-aminoguanine; 8-nitroguanine infusions increased 8-aminoguanine. Purine nucleoside phosphorylase (PNPase) converted 8-nitroguanosine to 8-nitroguanine and 8-aminoguanosine to 8-aminoguanine. Forodesine (PNPase inhibitor) reduced metabolism of 8-nitroguanosine by pathway 2 and shunted metabolism of 8-nitroguanosine to 8-aminoguanosine. In Dahl salt-sensitive rats, 8-nitroguanosine infusions increased kidney levels of 8-nitroguanine, 8-aminoguanosine and 8-aminoguanine. These results indicate that both pathways 1 and 2 participate in the biosynthesis of 8-aminoguanine in Sprague-Dawley and Dahl rats. Endogenous 8-aminoguanine in kidneys and urine were elevated many-fold in Dahl, compared to Sprague-Dawley, rats. The increased levels of 8-aminoguanine in Dahl rats were not due to alterations in pathways 1 and 2 but were associated with increased urine levels of endogenous 8-nitroguanosine suggesting that the "upstream" production of 8-nitroguanosine was increased in Dahl rats. Dahl rats are known to have high levels of peroxynitrite, and peroxynitrite is known to nitrate guanosine in biomolecules. Here we confirm that a peroxynitrite donor increases kidney levels of 8-aminoguanine. CONCLUSION 8-Aminoguanine occurs naturally via two distinct pathways and kidney levels of 8-aminoguanine are increased in Dahl rats, likely due to increased production of 8-nitroguanosine, a by-product of peroxynitrite chemistry.
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Changes in circulating exosome molecular profiles following surgery/(chemo)radiotherapy: early detection of response in head and neck cancer patients. Br J Cancer 2021; 125:1677-1686. [PMID: 34642463 PMCID: PMC8651659 DOI: 10.1038/s41416-021-01567-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 08/30/2021] [Accepted: 09/24/2021] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Head and neck cancers (HNSCC) are highly immunosuppressive. Plasma-derived exosomes of HNSCC patients carry immunomodulatory molecules, and their cargo correlates with clinical parameters. Here, we evaluated the exosomal molecular profile for early detection of treatment failure in locally advanced HNSCC patients treated with conventional therapy. METHODS Plasma from 17 HNSCC patients was collected before, during, and after treatment by surgery with adjuvant (chemo)radiation and at recurrence. Exosomes were isolated by size-exclusion chromatography. Total exosomal protein (TEP) was used to estimate exosome load and on-bead flow cytometry to evaluate relative fluorescence intensity (RFI) of tumour-associated and immunoregulatory proteins on exosomes. Exosomal effects on the activity of and adenosine production by T cells was assessed by flow cytometry and mass spectrometry. RESULTS TEP and the ratio of tumour-/immune-cell-derived exosomes varied during and after therapy with an overall decrease in the tumour-free follow-up but an increase at recurrence. RFI values of immunoregulatory proteins on exosomes, their ability for T cell inhibition and adenosine production changed during and after therapy. PD-L1 was the earliest discriminator for treatment failure and disease-free survival. CONCLUSIONS Monitoring of plasma exosomes during therapy represents a promising opportunity for early detection of treatment failure and risk stratification to delay/avoid recurrence.
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Dysregulated Purine Metabolism Contributes to Age-Associated Lower Urinary Tract Dysfunctions. ADVANCES IN GERIATRIC MEDICINE AND RESEARCH 2021; 3:e210018. [PMID: 34676378 PMCID: PMC8527459 DOI: 10.20900/agmr20210018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Lower urinary tract (LUT) dysfunction is common in the older adult. Aging is associated with a number of both storage and voiding problems which are classified into syndromes with overlapping symptoms. Despite the prevalence and consequences of these syndromes, LUT disorders continue to be undertreated as few therapeutic options exist. Here, we propose that dysregulated metabolism of purine nucleotides results in an accumulation of uro-damaging hypoxanthine (a source of reactive oxygen species or ROS), which provides a mechanism for defects in sensory signaling and contractility, culminating in abnormal urodynamic behavior.
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The Adenosine Pathway and Human Immunodeficiency Virus-Associated Inflammation. Open Forum Infect Dis 2021; 8:ofab396. [PMID: 34557556 PMCID: PMC8454523 DOI: 10.1093/ofid/ofab396] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 07/23/2021] [Indexed: 12/15/2022] Open
Abstract
Human immunodeficiency virus (HIV) is associated with an increased risk of age-associated comorbidities and mortality compared to people without HIV. This has been attributed to HIV-associated chronic inflammation and immune activation despite viral suppression. The adenosine pathway is an established mechanism by which the body regulates persistent inflammation to limit tissue damage associated with inflammatory conditions. However, HIV infection is associated with derangements in the adenosine pathway that limits its ability to control HIV-associated inflammation. This article reviews the function of purinergic signaling and the role of the adenosine signaling pathway in HIV-associated chronic inflammation. This review also discusses the beneficial and potential detrimental effects of pharmacotherapeutic strategies targeting this pathway among people with HIV.
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KIM-1-mediated anti-inflammatory activity is preserved by MUC1 induction in the proximal tubule during ischemia-reperfusion injury. Am J Physiol Renal Physiol 2021; 321:F135-F148. [PMID: 34151589 PMCID: PMC8424662 DOI: 10.1152/ajprenal.00127.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 05/27/2021] [Accepted: 05/27/2021] [Indexed: 11/22/2022] Open
Abstract
Cell-associated kidney injury molecule-1 (KIM-1) exerts an anti-inflammatory role following kidney injury by mediating efferocytosis and downregulating the NF-κB pathway. KIM-1 cleavage blunts its anti-inflammatory activities. We reported that mucin 1 (MUC1) is protective in a mouse model of ischemia-reperfusion injury (IRI). As both KIM-1 and MUC1 are induced in the proximal tubule (PT) during IRI and are a disintegrin and metalloprotease 17 (ADAM17) substrates, we tested the hypothesis that MUC1 protects KIM-1 activity. Muc1 knockout (KO) mice and wild-type (WT) littermates were subjected to IRI. KIM-1, MUC1, and ADAM17 levels (and signaling pathways) were assessed by immunoblot analysis. PT localization was assessed by confocal microscopy and an in situ proximity ligation assay. Findings were extended using human kidneys and urine as well as KIM-1-mediated efferocytosis assays in mouse PT cultures. In response to tubular injury in mouse and human kidneys, we observed induction and coexpression of KIM-1 and MUC1 in the PT. Compared with WT mice, Muc1 KO mice had higher urinary KIM-1 and lower kidney KIM-1. KIM-1 was apical in the PT of WT kidneys but predominately with luminal debris in Muc1 KO mice. Efferocytosis was reduced in Muc1 KO PT cultures compared with WT cultures, whereas inflammation was increased in Muc1 KO kidneys compared with WT kidneys. MUC1 was cleaved by ADAM17 in PT cultures and blocked KIM-1 shedding in Madin-Darby canine kidney cells. We conclude that KIM-1-mediated efferocytosis and thus anti-inflammatory activity during IRI is preserved in the injured kidney by MUC1 inhibition of KIM-1 shedding.NEW & NOTEWORTHY KIM-1 plays a key role in the recovery of the tubule epithelium during renal IRI by mediating efferocytosis and associated signaling that suppresses inflammation. Excessive cleavage of KIM-1 by ADAM17 provides a decoy receptor that aggravates efferocytosis and subsequent signaling. Our data from experiments in mice, patients, and cultured cells show that MUC1 is also induced during IRI and competes with KIM-1 for cleavage by ADAM17. Consequently, MUC1 protects KIM-1 anti-inflammatory activity in the damaged kidney.
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Breast Cancer Cell-Derived Adenosine Enhances Generation and Suppressor Function of Human Adaptive Regulatory T Cells. J Pers Med 2021; 11:jpm11080754. [PMID: 34442398 PMCID: PMC8401826 DOI: 10.3390/jpm11080754] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 07/28/2021] [Accepted: 07/28/2021] [Indexed: 12/28/2022] Open
Abstract
Introduction: Adaptive regulatory T cells (Tr1) are induced in the periphery by environmental stimuli. CD73 expression and adenosine (ADO) production by tumor cells may influence Tr1 generation and their immunosuppressive activity. Material and Methods: Tr1 were generated in co-cultures of CD4+CD25neg T cells, autologous immature dendritic cells (iDC), and irradiated ADO-producing CD73+ or non-producing CD73neg breast cancer (BrCa) cell lines (TU). The expression of ectonucleotidases and other surface markers on Tr1 was determined by flow cytometry. Tr1-mediated suppression of proliferation was evaluated in CFSE-based assays. Luciferase-based ATP detection assays and mass spectrometry were used to measure ATP hydrolysis and ADO levels. Cytokine levels were measured by ELISA or Luminex. CD73 expression on tumor cells or T cells in TU tissues was assessed by immunofluorescence. Results: CD73+ TU induced higher numbers of Tr1 cells (p < 0.01) than CD73neg TU. Tr1TU73+ hydrolyzed more exogenous ATP, produced more ADO, and mediated higher suppression than Tr1TU73neg (p < 0.05 for all). ARL67156, an ectonucleotidase inhibitor, and ZM241385, A2A receptor antagonist, reduced suppression of proliferation mediated by Tr1TU73+ cells (p < 0.01). Basal-like primary BrCa cells expressed higher levels of ectonucleotidases and induced more Tr1 than less aggressive primary luminal-like BrCa. Conclusion: BrCa producing ADO (CD73+ TU) favor the induction of Tr1, which expresses CD39 and CD73, hydrolyzes ATP to ADO, and effectively suppresses anti-tumor immunity.
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Mammary Epithelial and Endothelial Cell Spheroids as a Potential Functional In vitro Model for Breast Cancer Research. J Vis Exp 2021. [PMID: 34309602 DOI: 10.3791/62940] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Breast cancer is the leading cause of mortality in women. The growth of breast cancer cells and their subsequent metastasis is a key factor for its progression. Although the mechanisms involved in promoting breast cancer growth have been intensively studied using monocultures of breast cancer cells such as MCF-7 cells, the contribution of other cell types, such as vascular and lymphatic endothelial cells that are intimately involved in tumor growth, has not been investigated in depth. Cell-cell interaction plays a key role in tumor growth and progression. Neoangiogenesis, or the development of vessels, is essential for tumor growth, whereas the lymphatic system serves as a portal for cancer cell migration and subsequent metastasis. Recent studies provide evidence that vascular and lymphatic endothelial cells can significantly influence cancer cell growth. These observations imply a need for developing in vitro models that would more realistically reflect breast cancer growth processes in vivo. Moreover, restrictions in animal research require the development of ex vivo models to elucidate better the mechanisms involved. This article describes the development of breast cancer spheroids composed of both breast cancer cells (estrogen receptor-positive MCF-7 cells) and vascular and/or lymphatic endothelial cells. The protocol describes a detailed step-by-step approach in creating dual-cell spheroids using two different approaches, hanging drop (gold standard and cheap) and 96-well U-bottom plates (expensive). In-depth instructions are provided for how to delicately pick up the formed spheroids to monitor growth by microscopic sizing and assessing viability using dead and live cell staining. Moreover, procedures to fix the spheroids for sectioning and staining with growth-specific antibodies to differentiate growth patterns in spheroids are delineated. Additionally, details for preparing spheroids with transfected cells and methods to extract RNA for molecular analysis are provided. In conclusion, this article provides in-depth instructions for preparing multi-cell spheroids for breast cancer research.
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A uro-protective agent with restorative actions on urethral and striated muscle morphology. World J Urol 2021; 39:2685-2690. [PMID: 33078215 PMCID: PMC8053723 DOI: 10.1007/s00345-020-03492-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 10/07/2020] [Indexed: 01/02/2023] Open
Abstract
PURPOSE Aging increases oxidative stress, which can have delirious effects on smooth and striated muscle resulting in bladder dysfunction. Consequently, in women aged over 60 years, urinary incontinence (UI) is a prevalent health problem. Despite the prevalence and consequences, UI continues to be undertreated simply because there are few therapeutic options. METHODS Here we investigated whether 8-aminoguanine (8-AG), a purine nucleoside phosphorylase (PNPase inhibitor), would restore urethra and external sphincter (EUS) muscle morphology in the aged rat. Aged (> 25 months) female Fischer 344 rats were randomized to oral treatment with 8-AG (6 weeks) or placebo, and the urethra and EUS were evaluated by electron microscopy and protein expression (western immunoblotting). RESULTS Aging was associated with mitochondrial degeneration in smooth and striated muscle cells as compared to young rats. We also observed a significant increase in biomarkers such as PARP, a downstream activator of oxidative/nitrosative stress. Treatment of aged rats with 8-AG normalized all abnormalities to that of a younger state. CONCLUSIONS 8-AG, a potent inhibitor of PNPase, reverses age-related lower urinary tract morphological and biochemical changes. Our observations support the concept that 8-AG will reverse age-induced lower urinary tract disorders such as UI. These initial findings could have therapeutic implications for the prevention and treatment of age-related UI.
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INHIBITION OF PLATELET ACTIVATION UTILIZING A NOVEL GUIDEWIRE PLATFORM AND DRUG-LOADED HYDROPHILIC POLYMERS. J Am Coll Cardiol 2021. [DOI: 10.1016/s0735-1097(21)02328-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Long-Term Dipeptidyl Peptidase 4 Inhibition Worsens Hypertension and Renal and Cardiac Abnormalities in Obese Spontaneously Hypertensive Heart Failure Rats. J Am Heart Assoc 2021; 10:e020088. [PMID: 33682436 PMCID: PMC8174220 DOI: 10.1161/jaha.120.020088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Background The long-term effects of dipeptidyl peptidase 4 (DPP4) inhibitors on blood pressure and cardiovascular and renal health remain controversial. Herein, we investigated the extended (>182 days) effects of DPP4 inhibition in a model of spontaneous hypertension, heart failure, diabetes mellitus, obesity and hyperlipidemia. Methods and Results Adult obese spontaneously hypertensive heart failure rats (SHHF) were implanted with radio transmitters for measurement of arterial blood pressures. Two weeks later, SHHF were randomized to receive either a DPP4 inhibitor (sitagliptin, 80 mg/kg per day in drinking water) or placebo. At the end of the radiotelemetry measurements, renal and cardiac function and histology, as well as other relevant biochemical parameters, were assessed. For the first 25 days, mean arterial blood pressures were similar in sitagliptin-treated versus control SHHF; afterwards, mean arterial blood pressures increased more in sitagliptin-treated SHHF (P<0.000001). The time-averaged mean arterial blood pressures from day 26 through 182 were 7.2 mm Hg higher in sitagliptin-treated SHHF. Similar changes were observed for systolic (8.6 mm Hg) and diastolic (6.1 mm Hg) blood pressures, and sitagliptin augmented hypertension throughout the light-dark cycle. Long-term sitagliptin treatment also increased kidney weights, renal vascular resistances, the excretion of kidney injury molecule-1 (indicates injury to proximal tubules), renal interstitial fibrosis, glomerulosclerosis, renal vascular hypertrophy, left ventricular dysfunction, right ventricular degeneration, and the ratios of collagen IV/collagen III and collagen IV/laminin in the right ventricle. Conclusions These findings indicate that, in some genetic backgrounds, long-term DPP4 inhibitor treatment is harmful and identify an animal model to study mechanisms of, and test ways to prevent, DPP4 inhibitor-induced pathological conditions.
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A Randomized, Placebo-Controlled, Pilot Clinical Trial of Dipyridamole to Decrease Human Immunodeficiency Virus-Associated Chronic Inflammation. J Infect Dis 2021; 221:1598-1606. [PMID: 31282542 DOI: 10.1093/infdis/jiz344] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 07/04/2019] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Adenosine is a potent immunoregulatory nucleoside produced during inflammatory states to limit tissue damage. We hypothesized that dipyridamole, which inhibits cellular adenosine uptake, could raise the extracellular adenosine concentration and dampen chronic inflammation associated with human immunodeficiency virus (HIV) type 1. METHODS Virally suppressed participants receiving antiretroviral therapy were randomized 1:1 for 12 weeks of dipyridamole (100 mg 4 times a day) versus placebo capsules. All participants took open-label dipyridamole during weeks 12-24. Study end points included changes in markers of systemic inflammation (soluble CD163 and CD14, and interleukin 6) and levels of T-cell immune activation (HLA-DR+CD38+). RESULTS Of 40 participants who were randomized, 17 dipyridamole and 18 placebo recipients had baseline and week 12 data available for analyses. There were no significant changes in soluble markers, apart from a trend toward decreased levels of soluble CD163 levels (P = .09). There was a modest decrease in CD8+ T-cell activation (-17.53% change for dipyridamole vs +13.31% for placebo; P = .03), but the significance was lost in the pooled analyses (P = .058). Dipyridamole also reduced CD4+ T-cell activation (-11.11% change; P = .006) in the pooled analyses. In post hoc analysis, detectable plasma dipyridamole levels were associated with higher levels of inosine, an adenosine surrogate, and of cyclic adenosine monophosphate. CONCLUSION Dipyridamole increased extracellular adenosine levels and decreased T-cell activation significantly among persons with HIV-1 infection receiving virally suppressive therapy.
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CD26 expression and adenosine deaminase activity in regulatory T cells (Treg) and CD4(+) T effector cells in patients with head and neck squamous cell carcinoma. Oncoimmunology 2021; 1:659-669. [PMID: 22934258 PMCID: PMC3429570 DOI: 10.4161/onci.20387] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Adenosine deaminase (ADA) is responsible for the deamination of immunosuppressive adenosine to inosine. In human T lymphocytes, ADA is associated with dipeptidyl peptidase IV (CD26). ADA expression and activity were evaluated in regulatory T cells (Treg) and CD4(+) T effector cells (Teff) of patients with head and neck squamous cell cancer (HNSCC). CD4(+)CD39(+) and CD4(+)CD39(neg) T cells were isolated by single-cell sorting from the peripheral blood of 15 HNSCC patients and 15 healthy donors (NC). CD26/ADA expression in these cells was studied by multicolor flow cytometry, confocal microscopy, RT-PCR and immunohistochemistry in tumor tissues. ADA activity was evaluated by mass spectrometry, suppression of Teff proliferation in CFSE assays and cytokine production by Luminex. CD4(+)CD39(+) Treg had low and CD4(+)CD39(neg) Teff high CD26/ADA expression and ADA activity in NC or HNSCC. The frequency and suppressor activity of CD39(+)CD26(neg) Treg were elevated in patients relative to NC (p < 0.01). However, ADA activity in patients' CD4(+)CD39(neg) Teff was decreased (p < 0.05), resulting in extracellular adenosine accumulation. Also, patients' Teff were more sensitive to inhibitory signals delivered via adenosine receptors. IL-2, IL12 and INFγ upregulated ADA expression and activity in CD4(+)CD39(neg) Teff, whereas IL-10, PGE(2) and CADO downregulated it. The differentially expressed CD26/ADA can serve as surface markers for functionally-active CD39(+)CD26(neg) Treg.
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Abstract
Background The “no‐reflow phenomenon” compromises percutaneous coronary intervention outcomes. There is an unmet need for a device that prevents no‐reflow phenomenon. Our goal was to develop a guidewire platform comprising a nondisruptive hydrophilic coating that allows continuous delivery of adenosine throughout a percutaneous coronary intervention. Methods and Results We developed a guidewire with spaced coils to increase surface area for drug loading. Guidewires were plasma treated to attach hydroxyl groups to metal surfaces, and a methoxy–polyethylene glycol–silanol primer layer was covalently linked to hydroxyl groups. Using polyvinyl alcohol, polyvinyl pyrrolidone, and polyvinyl acetate, a drug layer containing jet‐milled adenosine was hydrogen‐bonded to the polyethylene glycol–silanol layer and coated with an outer diffusive barrier layer. Coatings were processed with a freeze/thaw curing method. In vitro release studies were conducted followed by in vivo evaluation in pigs. Coating quality, performance, and stability with sterilization were also evaluated. Antiplatelet properties of the guidewire were also determined. Elution studies with adenosine‐containing guidewires showed curvilinear and complete release of adenosine over 60 minutes. Porcine studies demonstrated that upon insertion into a coronary artery, adenosine‐releasing guidewires induced immediate and robust increases (2.6‐fold) in coronary blood flow velocity, which were sustained for ≈30 minutes without systemic hemodynamic effects or arrhythmias. Adenosine‐loaded wires prevented and reversed coronary vasoconstriction induced by acetylcholine. The wires significantly inhibited platelet aggregation by >80% in vitro. Guidewires passed bench testing for lubricity, adherence, integrity, and tracking. Conclusions Our novel drug‐releasing guidewire platform represents a unique approach to prevent/treat no‐reflow phenomenon during percutaneous coronary intervention.
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Paths to Successful Translation of New Therapies for Severe Traumatic Brain Injury in the Golden Age of Traumatic Brain Injury Research: A Pittsburgh Vision. J Neurotrauma 2020; 37:2353-2371. [PMID: 30520681 PMCID: PMC7698994 DOI: 10.1089/neu.2018.6203] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
New neuroprotective therapies for severe traumatic brain injury (TBI) have not translated from pre-clinical to clinical success. Numerous explanations have been suggested in both the pre-clinical and clinical arenas. Coverage of TBI in the lay press has reinvigorated interest, creating a golden age of TBI research with innovative strategies to circumvent roadblocks. We discuss the need for more robust therapies. We present concepts for traditional and novel approaches to defining therapeutic targets. We review lessons learned from the ongoing work of the pre-clinical drug and biomarker screening consortium Operation Brain Trauma Therapy and suggest ways to further enhance pre-clinical consortia. Biomarkers have emerged that empower choice and assessment of target engagement by candidate therapies. Drug combinations may be needed, and it may require moving beyond conventional drug therapies. Precision medicine may also link the right therapy to the right patient, including new approaches to TBI classification beyond the Glasgow Coma Scale or anatomical phenotyping-incorporating new genetic and physiologic approaches. Therapeutic breakthroughs may also come from alternative approaches in clinical investigation (comparative effectiveness, adaptive trial design, use of the electronic medical record, and big data). The full continuum of care must also be represented in translational studies, given the important clinical role of pre-hospital events, extracerebral insults in the intensive care unit, and rehabilitation. TBI research from concussion to coma can cross-pollinate and further advancement of new therapies. Misconceptions can stifle/misdirect TBI research and deserve special attention. Finally, we synthesize an approach to deliver therapeutic breakthroughs in this golden age of TBI research.
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Purine nucleoside phosphorylase inhibition ameliorates age-associated lower urinary tract dysfunctions. JCI Insight 2020; 5:140109. [PMID: 32910805 PMCID: PMC7605521 DOI: 10.1172/jci.insight.140109] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 09/04/2020] [Indexed: 12/29/2022] Open
Abstract
In the aging population, lower urinary tract (LUT) dysfunction is common and often leads to storage and voiding difficulties classified into overlapping symptom syndromes. Despite prevalence and consequences of these syndromes, LUT disorders continue to be undertreated simply because there are few therapeutic options. LUT function and structure were assessed in aged (>25 months) male and female Fischer 344 rats randomized to oral treatment with a purine nucleoside phosphorylase (PNPase inhibitor) 8-aminoguanine (8-AG) or vehicle for 6 weeks. The bladders of aged rats exhibited multiple abnormalities: tactile insensitivity, vascular remodeling, reduced collagen-fiber tortuosity, increased bladder stiffness, abnormal smooth muscle morphology, swelling of mitochondria, and increases in urodamaging purine metabolites. Treatment of aged rats with 8-AG restored all evaluated histological, ultrastructural, and physiological abnormalities toward that of a younger state. 8-AG is an effective treatment that ameliorates key age-related structural and physiologic bladder abnormalities. Because PNPase inhibition blocks metabolism of inosine to hypoxanthine and guanosine to guanine, likely uroprotective effects of 8-AG are mediated by increased bladder levels of uroprotective inosine and guanosine and reductions in urodamaging hypoxanthine and xanthine. These findings demonstrate that 8-AG has translational potential for treating age-associated LUT dysfunctions and resultant syndromes in humans.
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Abstract
Here, we tested the hypothesis that TNAP (tissue nonspecific alkaline phosphatase) modulates vascular responsiveness to norepinephrine. In the isolated, Tyrode's-perfused rat mesentery, 50 µmol/L of L-p-bromotetramisole (L-p-BT; selective TNAP inhibitor, Ki=56 µmol/L) significantly reduced TNAP activity and caused a significant 9.0-fold rightward-shift in the norepinephrine concentration versus vasoconstriction relationship. At 100 µmol/L, L-p-BT further reduced mesenteric TNAP activity and caused an additional significant right-shift of the norepinephrine concentration versus vasoconstriction relationship. A higher concentration (200 µmol/L) of L-p-BT had no further effect on either mesenteric TNAP activity or norepinephrine-induced vasoconstriction. L-p-BT did not alter vascular responses to vasopressin, thus ruling-out nonspecific suppression of vascular reactivity. Since in the rat mesenteric vasculature α1-adrenoceptors mediate norepinephrine-induced vasoconstriction, these finding indicate that TNAP inhibition selectively interferes with α1-adrenoceptor signaling. Additional experiments showed that the effects of TNAP inhibition on norepinephrine-induced vasoconstriction were not mediated by accumulation of pyrophosphate or ATP (TNAP substrates) nor by reduced adenosine levels (TNAP product). TNAP inhibition significantly reduced the Hillslope of the norepinephrine concentration versus vasoconstriction relationship from 1.8±0.2 (consistent with positive cooperativity of α1-adrenoceptor signaling) to 1.0±0.1 (no cooperativity). Selective activation of A1-adenosine receptors, which are known to participate in coincident signaling with α1-adrenoceptors, reversed the suppressive effects of L-p-BT on norepinephrine-induced vasoconstriction. In vivo, L-p-BT administration achieved plasma levels of ≈60 µmol/L and inhibited mesenteric vascular responses to exogenous norepinephrine and sympathetic nerve stimulation. TNAP modulates vascular responses to norepinephrine likely by affecting positive cooperativity of α1-adrenoceptor signaling via a mechanism involving A1 receptor signaling.
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Immune Suppressive Effects of Plasma-Derived Exosome Populations in Head and Neck Cancer. Cancers (Basel) 2020; 12:cancers12071997. [PMID: 32708274 PMCID: PMC7409343 DOI: 10.3390/cancers12071997] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 07/17/2020] [Accepted: 07/18/2020] [Indexed: 12/20/2022] Open
Abstract
Plasma-derived exosomes of head and neck squamous cell carcinoma (HNSCC) patients carry inhibitory factors mediating immune suppression. Separation of tumor-derived exosomes (TEX) and non-TEX may assist in a better understanding of their respective parental cells. Here, we evaluate the impact of TEX or hematopoietic-derived exosomes on immune suppression. We evaluated apoptosis in CD8+ T cells, conversion of CD4+ T cells to regulatory T cells (Treg), and adenosine production by TEX, non-TEX, or total exosomes. Exosome protein cargo was significantly higher in total and CD45(−) exosomes from high stage compared to low stage patients. Furthermore, total and CD45(−) exosomes of high stage patients induced more apoptosis in CD8+ T cells than their low stage counterparts. CD69 suppression, a marker of reduced CD8+ T cell activation, was only mediated by CD45(−) exosomes. All fractions induced Treg differentiation, defined by CD39 expression, but only CD45(−) exosomes showed a stage-dependent conversion. CD45(−) exosomes produced higher adenosine concentrations than CD45(+) exosomes, concluding that adenosine production measured in total exosomes mainly derives from TEX. The presented results show significant induction of immune suppression by TEX in HNSCC. This immunosuppressive effect supports the potential role of exosomes as liquid biomarkers for disease stage and level of immune suppression.
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Purine Metabolites in Tumor-Derived Exosomes May Facilitate Immune Escape of Head and Neck Squamous Cell Carcinoma. Cancers (Basel) 2020; 12:cancers12061602. [PMID: 32560461 PMCID: PMC7352909 DOI: 10.3390/cancers12061602] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 06/10/2020] [Accepted: 06/15/2020] [Indexed: 02/06/2023] Open
Abstract
Body fluids of patients with head and neck squamous cell carcinoma (HNSCC) are enriched in exosomes that reflect properties of the tumor. The aim of this study was to determine whether purine metabolites are carried by exosomes and evaluate their role as potential contributors to tumor immune escape. The gene expression levels of the purine synthesis pathway were studied using the Cancer Genome Atlas (TCGA) Head and Neck Cancer database. Exosomes were isolated from supernatants of UMSCC47 cells and from the plasma of HNSCC patients (n = 26) or normal donors (NDs; n = 5) using size exclusion chromatography. Ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used to assess levels of 19 purine metabolites carried by exosomes. In HNSCC tissues, expression levels of genes involved in the purinergic pathway were upregulated indicating an accelerated purine metabolism compared to normal tissues. Exosomes from supernatants of UMSCC47 cells contained several purine metabolites, predominantly adenosine and inosine. Purine metabolite levels were enriched in exosomes isolated from the plasma of HNSCC patients compared to those isolated from NDs and carried elevated levels of adenosine (p = 0.0223). Exosomes of patients with early-stage disease and no lymph node metastasis contained significantly elevated levels of adenosine and 5'-GMP (p = 0.0247 and p = 0.0229, respectively). The purine metabolite levels in exosomes decreased in patients with advanced cancer and nodal involvement. This report provides the first evidence that HNSCC cells shuttle purine metabolites in exosomes, with immunosuppressive adenosine being the most prominent purine. Changes in the content and levels of purine metabolites in circulating exosomes reflect disease progression in HNSCC patients.
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Abstract
Exosomes, small-sized extracellular vesicles, carry components of the purinergic pathway. The production by cells of exosomes carrying this pathway remains poorly understood. Here, we asked whether type 1, 2A, or 2B adenosine receptors (A1Rs, A2ARs, and A2BRs, respectively) expressed by producer cells are involved in regulating exosome production. Preglomerular vascular smooth muscle cells (PGVSMCs) were isolated from wildtype, A1R-/-, A2AR-/-, and A2BR-/- rats, and exosome production was quantified under normal or metabolic stress conditions. Exosome production was also measured in various cancer cells treated with pharmacologic agonists/antagonists of A1Rs, A2ARs, and A2BRs in the presence or absence of metabolic stress or cisplatin. Functional activity of exosomes was determined in Jurkat cell apoptosis assays. In PGVSMCs, A1R and A2AR constrained exosome production under normal conditions (p = 0.0297; p = 0.0409, respectively), and A1R, A2AR, and A2BR constrained exosome production under metabolic stress conditions. Exosome production from cancer cells was reduced (p = 0.0028) by the selective A2AR agonist CGS 21680. These exosomes induced higher levels of Jurkat apoptosis than exosomes from untreated cells or cells treated with A1R and A2BR agonists (p = 0.0474). The selective A2AR antagonist SCH 442416 stimulated exosome production under metabolic stress or cisplatin treatment, whereas the selective A2BR antagonist MRS 1754 reduced exosome production. Our findings indicate that A2ARs suppress exosome release in all cell types examined, whereas effects of A1Rs and A2BRs are dependent on cell type and conditions. Pharmacologic targeting of cancer with A2AR antagonists may inadvertently increase exosome production from tumor cells.
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Characterization of the N 6-etheno-bridge method to assess extracellular metabolism of adenine nucleotides: detection of a possible role for purine nucleoside phosphorylase in adenosine metabolism. Purinergic Signal 2020; 16:187-211. [PMID: 32367441 PMCID: PMC7367995 DOI: 10.1007/s11302-020-09699-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Accepted: 04/08/2020] [Indexed: 12/11/2022] Open
Abstract
The goal of this study was to determine the validity of using N6-etheno-bridged adenine nucleotides to evaluate ecto-nucleotidase activity. We observed that the metabolism of N6-etheno-ATP versus ATP was quantitatively similar when incubated with recombinant CD39, ENTPD2, ENTPD3, or ENPP-1, and the quantitative metabolism of N6-etheno-AMP versus AMP was similar when incubated with recombinant CD73. This suggests that ecto-nucleotidases process N6-etheno-bridged adenine nucleotides similarly to endogenous adenine nucleotides. Four cell types rapidly (t1/2, 0.21 to 0.66 h) metabolized N6-etheno-ATP. Applied N6-etheno-ATP was recovered in the medium as N6-etheno-ADP, N6-etheno-AMP, N6-etheno-adenosine, and surprisingly N6-etheno-adenine; intracellular N6-etheno compounds were undetectable. This suggests minimal cellular uptake, intracellular metabolism, or deamination of these compounds. N6-etheno-ATP, N6-etheno-ADP, N6-etheno-AMP, N6-etheno-adenosine, and N6-etheno-adenine had little affinity for recombinant A1, A2A, or A2B receptors, for a subset of P2X receptors (3H-α,β-methylene-ATP binding to rat bladder membranes), or for a subset of P2Y receptors (35S-ATP-αS binding to rat brain membranes), suggesting minimal pharmacological activity. N6-etheno-adenosine was partially converted to N6-etheno-adenine in four different cell types; this was blocked by purine nucleoside phosphorylase (PNPase) inhibition. Intravenous N6-etheno-ATP was quickly metabolized, with N6-etheno-adenine being the main product in naïve rats, but not in rats pretreated with a PNPase inhibitor. PNPase inhibition reduced the urinary excretion of endogenous adenine and attenuated the conversion of exogenous adenosine to adenine in the renal cortex. The N6-etheno-bridge method is a valid technique to assess extracellular metabolism of adenine nucleotides by ecto-nucleotidases. Also, rats express an enzyme with PNPase-like activity that metabolizes N6-etheno-adenosine to N6-etheno-adenine.
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Simultaneous Inhibition of Glycolysis and Oxidative Phosphorylation Triggers a Multi-Fold Increase in Secretion of Exosomes: Possible Role of 2'3'-cAMP. Sci Rep 2020; 10:6948. [PMID: 32332778 PMCID: PMC7181876 DOI: 10.1038/s41598-020-63658-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 03/31/2020] [Indexed: 12/19/2022] Open
Abstract
Exosome secretion by cells is a complex, poorly understood process. Studies of exosomes would be facilitated by a method for increasing their production and release. Here, we present a method for stimulating the secretion of exosomes. Cultured cells were treated or not with sodium iodoacetate (IAA; glycolysis inhibitor) plus 2,4-dinitrophenol (DNP; oxidative phosphorylation inhibitor). Exosomes were isolated by size-exclusion chromatography and their morphology, size, concentration, cargo components and functional activity were compared. IAA/DNP treatment (up to 10 µM each) was non-toxic and resulted in a 3 to 16-fold increase in exosome secretion. Exosomes from IAA/DNP-treated or untreated cells had similar biological properties and functional effects on endothelial cells (SVEC4-10). IAA/DNP increased exosome secretion from mouse organ cultures, and in vivo injections enhanced the levels of circulating exosomes. IAA/DNP decreased ATP levels (p < 0.05) in cells. A cell membrane-permeable form of 2',3'-cAMP and 3'-AMP mimicked the potentiating effects of IAA/DNP on exosome secretion. In cells lacking 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase; an enzyme that metabolizes 2',3'-cAMP into 2'- and 3'-AMP), effects of IAA/DNP on exosome secretion were enhanced. The IAA/DNP combination is a powerful stimulator of exosome secretion, and these stimulatory effects are, in part, mediated by intracellular 2',3'-cAMP.
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MESH Headings
- 2',3'-Cyclic-Nucleotide Phosphodiesterases/deficiency
- 2',3'-Cyclic-Nucleotide Phosphodiesterases/genetics
- 2,4-Dinitrophenol/pharmacology
- Animals
- Animals, Genetically Modified
- Biomarkers, Tumor/metabolism
- Blotting, Western
- Cell Line, Tumor
- Cyclic AMP/metabolism
- Exosomes/metabolism
- Female
- Glycolysis/drug effects
- Glycolysis/genetics
- Humans
- Iodoacetic Acid/pharmacology
- Mice
- Mice, Inbred C57BL
- Microscopy, Electron, Transmission
- Oxidative Phosphorylation/drug effects
- Rats
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Abstract
The role of exosomes in different physiological and pathological settings is an emerging field of great current interest. One hallmark of exosomes is the promotion of blood vessel formation. Exosomes of different cellular origin have been shown to be enriched in angiogenic proteins which directly promote angiogenesis. In addition, exosomes are also efficacious producers of adenosine and potentially encapsulate adenosine in their lumen. The adenosine content of exosomes has been linked to their immunosuppressive effects. In this communication, we consider the possibility that adenosine production by tumor cell-derived exosomes may represent a novel pathway for stimulation of angiogenesis in the tumor microenvironment.
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Intercalated cell BKα subunit is required for flow-induced K+ secretion. JCI Insight 2020; 5:130553. [PMID: 32255763 DOI: 10.1172/jci.insight.130553] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 03/25/2020] [Indexed: 12/13/2022] Open
Abstract
BK channels are expressed in intercalated cells (ICs) and principal cells (PCs) in the cortical collecting duct (CCD) of the mammalian kidney and have been proposed to be responsible for flow-induced K+ secretion (FIKS) and K+ adaptation. To examine the IC-specific role of BK channels, we generated a mouse with targeted disruption of the pore-forming BK α subunit (BKα) in ICs (IC-BKα-KO). Whole cell charybdotoxin-sensitive (ChTX-sensitive) K+ currents were readily detected in control ICs but largely absent in ICs of IC-BKα-KO mice. When placed on a high K+ (HK) diet for 13 days, blood [K+] was significantly greater in IC-BKα-KO mice versus controls in males only, although urinary K+ excretion rates following isotonic volume expansion were similar in males and females. FIKS was present in microperfused CCDs isolated from controls but was absent in IC-BKα-KO CCDs of both sexes. Also, flow-stimulated epithelial Na+ channel-mediated (ENaC-mediated) Na+ absorption was greater in CCDs from female IC-BKα-KO mice than in CCDs from males. Our results confirm a critical role of IC BK channels in FIKS. Sex contributes to the capacity for adaptation to a HK diet in IC-BKα-KO mice.
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Activation of AMP-activated protein kinase during sepsis/inflammation improves survival by preserving cellular metabolic fitness. FASEB J 2020; 34:7036-7057. [PMID: 32246808 DOI: 10.1096/fj.201901900r] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 01/24/2020] [Accepted: 03/18/2020] [Indexed: 01/08/2023]
Abstract
The purpose was to determine the role of AMPK activation in the renal metabolic response to sepsis, the development of sepsis-induced acute kidney injury (AKI) and on survival. In a prospective experimental study, 167 10- to 12-week-old C57BL/6 mice underwent cecal ligation and puncture (CLP) and human proximal tubule epithelial cells (TEC; HK2) were exposed to inflammatory mix (IM), a combination of lipopolysaccharide (LPS) and high mobility group box 1 (HMGB1). Renal/TEC metabolic fitness was assessed by monitoring the expression of drivers of oxidative phosphorylation (OXPHOS), the rates of utilization of OXPHOS/glycolysis in response to metabolic stress, and mitochondrial function by measuring O2 consumption rates (OCR) and the membrane potential (Δψm ). Sepsis/IM resulted in AKI, increased mortality, and in renal AMPK activation 6-24 hours after CLP/IM. Pharmacologic activation of AMPK with 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) or metformin during sepsis improved the survival, while AMPK inhibition with Compound C increased mortality, impaired mitochondrial respiration, decreased OCR, and disrupted TEC metabolic fitness. AMPK-driven protection was associated with increased Sirt 3 expression and restoration of metabolic fitness. Renal AMPK activation in response to sepsis/IM is an adaptive mechanism that protects TEC, organs, and the host by preserving mitochondrial function and metabolic fitness likely through Sirt3 signaling.
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Kinetic control of signaling: role of RGS proteins and GRKs. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.07005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Abstract
BACKGROUND Mesenchymal stromal cells (MSC) are multipotent progenitor cells found in the tumor microenvironment. They have an innate and regulatory immune activity, and they are able to produce immunosuppressive adenosine (ADO) via their ectonucleotidases CD39 and CD73. The present study explores ADO metabolism of MSC in relation to their developmental status. METHODS We analyzed MSC (n = 6), chondrogenic progenitor cells (CPC, n = 8), and chondrocytes (n = 8) for surface markers by flow cytometry. The ability to hydrolyze ATP and to produce ADO was tested by luminescence assays and mass spectrometry. RESULTS Significant differences in the surface marker expression of MSC, CPC, and chondrocytes were seen. While the expression of CD73 was observed to be the same on all cell types, the expression of the ectonucleotidase CD39 was significantly increased on MSC. Consequently, production of ADO was most abundant in MSC as compared with chondrocytes and CPC. CONCLUSION Mesenchymal stromal cells are potent producers of ADO and are, therefore, able to increase immunosuppression. As MSC differentiate into chondrocytes, they lose this ability and may take on other functions.
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DPP4 Inhibition, NPY 1-36, PYY 1-36, SDF-1 α, and a Hypertensive Genetic Background Conspire to Augment Cell Proliferation and Collagen Production: Effects That Are Abolished by Low Concentrations of 2-Methoxyestradiol. J Pharmacol Exp Ther 2020; 373:135-148. [PMID: 32015161 PMCID: PMC7174788 DOI: 10.1124/jpet.119.263467] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 01/30/2020] [Indexed: 12/13/2022] Open
Abstract
By reducing their metabolism, dipeptidyl peptidase 4 inhibition (DPP4I) enhances the effects of numerous peptides including neuropeptide Y1–36 (NPY1–36), peptide YY1–36 (PYY1–36), and SDF-1α. Studies show that separately NPY1–36, PYY1–36 and SDF-1α stimulate proliferation of, and collagen production by, cardiac fibroblasts (CFs), preglomerular vascular smooth muscle cells (PGVSMCs), and glomerular mesangial cells (GMCs), particularly in cells isolated from genetically hypertensive rats. Whether certain combinations of these factors, in the absence or presence of DPP4I, are more profibrotic than others is unknown. Here we contrasted 24 different combinations of conditions (DPP4I, hypertensive genotype and physiologic levels [3 nM] of NPY1–36, PYY1–36, or SDF-1α) on proliferation of, and [3H]-proline incorporation by, CFs, PGVSMCs, and GMCs. In all three cell types, the various treatment conditions differentially increased proliferation and [3H]-proline incorporation, with a hypertensive genotype + DPP4I + NPY1–36 + SDF-1α being the most efficacious combination. Although the effects of this four-way combination were similar in male versus female CFs, physiologic (1 nM) concentrations of 2-methoxyestradiol (2ME; nonestrogenic metabolite of 17β-estradiol), abolished the effects of this combination in both male and female CFs. In conclusion, this study demonstrates that CFs, PGVSMCs, and GMCs are differentially activated by various combinations of NPY1–36, PYY1–36, SDF-1α, a hypertensive genetic background and DPP4I. We hypothesize that as these progrowth conditions accumulate, a tipping point would be reached that manifests in the long term as organ fibrosis and that 2ME would obviate any profibrotic effects of DPP4I, even under the most profibrotic conditions (i.e., hypertensive genotype with high NPY1–36 + SDF-1α levels and low 2ME levels).
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Estradiol Metabolism: Crossroads in Pulmonary Arterial Hypertension. Int J Mol Sci 2019; 21:ijms21010116. [PMID: 31877978 PMCID: PMC6982327 DOI: 10.3390/ijms21010116] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 12/17/2019] [Indexed: 12/17/2022] Open
Abstract
Pulmonary arterial hypertension (PAH) is a debilitating and progressive disease that predominantly develops in women. Over the past 15 years, cumulating evidence has pointed toward dysregulated metabolism of sex hormones in animal models and patients with PAH. 17β-estradiol (E2) is metabolized at positions C2, C4, and C16, which leads to the formation of metabolites with different biological/estrogenic activity. Since the first report that 2-methoxyestradiol, a major non-estrogenic metabolite of E2, attenuates the development and progression of experimental pulmonary hypertension (PH), it has become increasingly clear that E2, E2 precursors, and E2 metabolites exhibit both protective and detrimental effects in PH. Furthermore, both experimental and clinical data suggest that E2 has divergent effects in the pulmonary vasculature versus right ventricle (estrogen paradox in PAH). The estrogen paradox is of significant clinical relevance for understanding the development, progression, and prognosis of PAH. This review updates experimental and clinical findings and provides insights into: (1) the potential impacts that pathways of estradiol metabolism (EMet) may have in PAH; (2) the beneficial and adverse effects of estrogens and their precursors/metabolites in experimental PH and human PAH; (3) the co-morbidities and pathological conditions that may alter EMet and influence the development/progression of PAH; (4) the relevance of the intracrinology of sex hormones to vascular remodeling in PAH; and (5) the advantages/disadvantages of different approaches to modulate EMet in PAH. Finally, we propose the three-tier-estrogen effects in PAH concept, which may offer reconciliation of the opposing effects of E2 in PAH and may provide a better understanding of the complex mechanisms by which EMet affects the pulmonary circulation–right ventricular interaction in PAH.
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8-Aminoguanine Induces Diuresis, Natriuresis, and Glucosuria by Inhibiting Purine Nucleoside Phosphorylase and Reduces Potassium Excretion by Inhibiting Rac1. J Am Heart Assoc 2019; 7:e010085. [PMID: 30608204 PMCID: PMC6404173 DOI: 10.1161/jaha.118.010085] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Background 8-Aminoguanosine and 8-aminoguanine are K+-sparing natriuretics that increase glucose excretion. Most effects of 8-aminoguanosine are due to its metabolism to 8-aminoguanine. However, the mechanism by which 8-aminoguanine affects renal function is unknown and is the focus of this investigation. Methods and Results Because 8-aminoguanine has structural similarities with inhibitors of the epithelial sodium channel (ENaC), Na+/H+ exchangers, and adenosine A1 receptors, we examined the effects of 8-aminoguanine on EN aC activity in mouse collecting duct cells, on intracellular pH of human proximal tubular epithelial cells, on responses to a selective A1-receptor agonist in vivo, and on renal excretory function in A1-receptor knockout rats. These experiments showed that 8-aminoguanine did not block EN aC, Na+/H+ exchangers, or A1 receptors. Because Rac1 enhances activity of mineralocorticoid receptors and some guanosine analogues inhibit Rac1, we examined the effects of 8-aminoguanine on Rac1 activity in mouse collecting duct cells. Rac1 activity was significantly inhibited by 8-aminoguanine. Because in vitro 8-aminoguanine is a purine nucleoside phosphorylase ( PNP ase) inhibitor, we examined the effects of a natriuretic dose of 8-aminoguanine on urinary excretion of PNP ase substrates and products. 8-Aminoguanine increased and decreased, respectively, urinary excretion of PNP ase substrates and products. Next we compared in rats the renal effects of intravenous doses of 9-deazaguanine ( PNP ase inhibitor) versus 8-aminoguanine. 8-Aminoguanine and 9-deazaguanine induced similar increases in urinary Na+ and glucose excretion, yet only 8-aminoguanine reduced K+ excretion. Nsc23766 (Rac1 inhibitor) mimicked the effects of 8-aminoguanine on K+ excretion. Conclusions 8-Aminoguanine increases Na+ and glucose excretion by blocking PNP ase and decreases K+ excretion by inhibiting Rac1.
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Adenosine, Via A 2B Receptors, Inhibits Human (P-SMC) Progenitor Smooth Muscle Cell Growth. Hypertension 2019; 75:109-118. [PMID: 31786976 DOI: 10.1161/hypertensionaha.119.13698] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
c-Kit+ progenitor smooth muscle cells (P-SMCs) can develop into SMCs that contribute to injury-induced neointimal thickening. Here, we investigated whether adenosine reduces P-SMC migration and proliferation and whether this contributes to adenosine's inhibitory actions on neointima formation. In human P-SMCs, 2-chloroadenosine (stable adenosine analogue) and BAY60-6583 (A2B agonist) inhibited P-SMC proliferation and migration. Likewise, increasing endogenous adenosine by blocking adenosine metabolism with erythro-9-(2-hydroxy-3-nonyl) adenine (inhibits adenosine deaminase) and 5-iodotubercidin (inhibits adenosine kinase) attenuated P-SMC proliferation and migration. Neither N6-cyclopentyladenosine (A1 agonist), CGS21680 (A2A agonist), nor N6-(3-iodobenzyl)-adenosine-5'-N-methyluronamide (A3 agonist) affected P-SMC proliferation or migration. 2-Chloroadenosine increased cyclic AMP, reduced Akt phosphorylation (activates cyclin D expression), and reduced levels of cyclin D1 (promotes cell-cycle progression). Moreover, 2-chloroadenosine inhibited expression of Skp2 (promotes proteolysis of p27Kip1) and upregulated levels of p27Kip1 (negative cell-cycle regulator). A2B receptor knockdown prevented the effects of 2-chloroadenosine on cyclic AMP production and P-SMC proliferation and migration. Likewise, inhibition of adenylyl cyclase and protein kinase A rescued P-SMCs from the inhibitory effects of 2-chloroadenosine. The inhibitory effects of adenosine were similar in male and female P-SMCs. In vivo, peri-arterial (rat carotid artery) 2-chloroadenosine (20 μmol/L for 7 days) reduced neointimal hyperplasia by 64.5% (P<0.05; intima/media ratio: control, 1.4±0.02; treated, 0.53±0.012) and reduced neointimal c-Kit+ cells. Adenosine inhibits P-SMC migration and proliferation via the A2B receptor/cyclic AMP/protein kinase A axis, which reduces cyclin D1 expression and activity via inhibiting Akt phosphorylation and Skp2 expression and upregulating p27kip1 levels. Adenosine attenuates neointima formation in part by inhibiting infiltration and proliferation of c-Kit+ P-SMCs.
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Mechanism of 17β-estradiol stimulated integration of human mesenchymal stem cells in heart tissue. J Mol Cell Cardiol 2019; 133:115-124. [PMID: 31201797 DOI: 10.1016/j.yjmcc.2019.06.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 05/21/2019] [Accepted: 06/11/2019] [Indexed: 01/25/2023]
Abstract
Scarcity of gender specific donor hearts highlights the importance of mesenchymal stem cells (MSCs) as a therapeutic tool for heart repair. However, inefficient incorporation, retention, and activity of MSCs in cardiac tissue remain an obstacle. Since surges in follicular estradiol (E2; μmolar-range) trigger tissue remodeling (e.g. ovulation) and E2 exerts beneficial actions on the cardiovascular system, we hypothesized that E2 may promote/improve MSC-mediated cardiac repair processes. Using Wharton's jelly (WJ)-derived MSCs we assessed the effects of E2 on MSC proliferation, directed migration, and engraftment in murine heart slices (using xCELLigence real-time cell-impedance system, DNA quantification, and microscopy) and on MSC-induced angiogenesis in vivo (matrigel plug assay). Protein expression was assessed by Western blotting, ELISA/Luminex, and proteomic analysis; whereas mRNA expression was assessed by qRT-PCR. MSCs expressed estrogen receptors (ERs) -alpha and -beta. E2 promoted MSC proliferation and up-regulated mRNA and protein expression of ER-alpha, ER-beta, extracellular matrix metalloproteinase inducer (EMMPRIN), and matrix metalloproteinase (MMP) -9, yet down-regulated MMP-2 expression. Moreover, E2 up-regulated expression of vascular endothelial growth factor (VEGF)-A, VEGFR-2, vascular cell adhesion protein-1 (VCAM-1), and angiogenin (ANG) and stimulated nitric oxide (NO) production via ER. Proteomic analysis of MSCs showed that E2 up-regulated 47 proteins, down-regulated 7 proteins, and increased the expression of key biochemical components/pathways involved in tissue repair. In MSCs co-cultured with murine heart-slices, E2 significantly induced MSC migration in an ER-alpha-dependent fashion and significantly increased the secretion of MMP-2, MMP-9, ANG, and VEGF. In an in vivo matrigel assay, E2-treated MSCs increased angiogenesis and hemoglobin content. In conclusion, E2-treatment increases the incorporation of MSCs in heart slices and promotes MSC-induced angiogenesis. These beneficial effects are mediated via increases in molecules/pathways involved in tissue remodeling and angiogenesis. We speculate that E2 may enhance MSC ability to repair/regenerate cardiac tissue.
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2',3'-cGMP exists in vivo and comprises a 2',3'-cGMP-guanosine pathway. Am J Physiol Regul Integr Comp Physiol 2019; 316:R783-R790. [PMID: 30789788 PMCID: PMC6620655 DOI: 10.1152/ajpregu.00401.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 02/11/2019] [Accepted: 02/19/2019] [Indexed: 01/10/2023]
Abstract
The discovery in 2009 that 2',3'-cAMP exists in biological systems was rapidly followed by identification of 2',3'-cGMP in cell and tissue extracts. To determine whether 2',3'-cGMP exists in mammals under physiological conditions, we used ultraperformance LC-MS/MS to measure 2',3'-cAMP and 2',3'-cGMP in timed urine collections (via direct bladder cannulation) from 25 anesthetized mice. Urinary excretion rates (means ± SE) of 2',3'-cAMP (15.5 ± 1.8 ng/30 min) and 2',3'-cGMP (17.9 ± 1.9 ng/30 min) were similar. Mice also excreted 2'-AMP (3.6 ± 1.1 ng/20 min) and 3'-AMP (9.5 ± 1.2 ng/min), hydrolysis products of 2',3'-cAMP, and 2'-GMP (4.7 ± 1.7 ng/30 min) and 3'-GMP (12.5 ± 1.8 ng/30 min), hydrolysis products of 2',3'-cGMP. To validate that the chromatographic signals were from these endogenous noncanonical nucleotides, we repeated these experiments in mice (n = 18) lacking 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase), an enzyme known to convert 2',3'-cyclic nucleotides to their corresponding 2'-nucleotides. In CNPase-knockout mice, urinary excretions of 2',3'-cAMP, 3'-AMP, 2',3'-cGMP, and 3'-GMP were increased, while urinary excretions of 2'-AMP and 2'-GMP were decreased. Infusions of exogenous 2',3'-cAMP increased urinary excretion of 2',3'-cAMP, 2'-AMP, 3'-AMP, and adenosine, whereas infusions of exogenous 2',3'-cGMP increased excretion of 2',3'-cGMP, 2'-GMP, 3'-GMP, and guanosine. Together, these data suggest the endogenous existence of not only a 2',3'-cAMP-adenosine pathway (2',3'-cAMP → 2'-AMP/3'-AMP → adenosine), which was previously identified, but also a 2',3'-cGMP-guanosine pathway (2',3'-cGMP → 2'-GMP/3'-GMP → guanosine), observed here for the first time. Because it is well known that adenosine and guanosine protect tissues from injury, our data support the concept that both pathways may work together to protect tissues from injury.
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Abstract
SDF-1α (stromal cell-derived factor-1α) is a CXCR4-receptor agonist and DPP4 (dipeptidyl peptidase 4) substrate. SDF-1α, particularly when combined with sitagliptin to block the metabolism of SDF-1α by DPP4, stimulates proliferation of cardiac fibroblasts via the CXCR4 receptor; this effect is greater in cells from spontaneously hypertensive rats versus Wistar-Kyoto normotensive rats. Emerging evidence indicates that ubiquitin(1-76) exists in plasma and is a potent CXCR4-receptor agonist. Therefore, we hypothesized that ubiquitin(1-76), similar to SDF-1α, should increase proliferation of cardiac fibroblasts. Contrary to our working hypothesis, ubiquitin(1-76) did not stimulate cardiac fibroblast proliferation, yet unexpectedly antagonized the proproliferative effects of SDF-1α combined with sitagliptin. In this regard, ubiquitin(1-76) was more potent in spontaneously hypertensive versus Wistar-Kyoto cells. In the presence of 6bk (selective inhibitor of insulin-degrading enzyme [IDE]; an enzyme known to convert ubiquitin(1-76) to ubiquitin(1-74)), ubiquitin(1-76) no longer antagonized the proproliferative effects of SDF-1α/sitagliptin. Ubiquitin(1-74) also antagonized the proproliferative effects of SDF-1α/sitagliptin, and this effect of ubiquitin(1-74) was not blocked by 6bk and was >10-fold more potent compared with ubiquitin(1-76). Neither ubiquitin(1-76) nor ubiquitin(1-74) inhibited the proproliferative effects of the non-CXCR4 receptor agonist neuropeptide Y (activates Y1 receptors). Cardiac fibroblasts expressed IDE mRNA, protein, and activity and converted ubiquitin(1-76) to ubiquitin(1-74). Spontaneously hypertensive fibroblasts expressed greater IDE activity. Extracellular ubiquitin(1-76) blocks the proproliferative effects of SDF-1α/sitagliptin via its conversion by IDE to ubiquitin(1-74), a potent CXCR4 antagonist. Thus, IDE inhibitors, particularly when combined with DPP4 inhibitors or hypertension, could increase the risk of cardiac fibrosis.
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Kinetic changes in Ga cycling can increase cAMP accumulation while decreasing G protein‐coupled receptor kinase‐mediated receptor desensitization. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.502.7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Aging increases the expression of vasopressin receptors in both the kidney and urinary bladder. Neurourol Urodyn 2019; 38:393-397. [PMID: 30311671 PMCID: PMC9839378 DOI: 10.1002/nau.23830] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 09/06/2018] [Accepted: 09/10/2018] [Indexed: 01/17/2023]
Abstract
AIMS The goal of this study was to determine whether aging effects the expression of V1a and V2 vasopressin receptors in the urinary bladder mucosa (UBM) and kidney. METHODS UBM and kidneys were obtained from young (3 months-of-age) and old (25-30 months-of-age) female Fisher 344 rats. Tissue samples were analyzed by western blotting for V1a and V2 receptor expression, and rat plasma levels of vasopressin levels were measured by ELISA. RESULTS V1a and V2 receptors were detected in both the UBM and kidneys. Aging significantly (P < 0.05) increased the expression of V2 receptors by 2.80 ± 0.52 and 6.52 ± 1.24-fold in the UBM and kidneys, respectively. Aging also increased V1a receptor expression in the kidneys (5.52 ± 1.05 fold; P < 0.05), but not in the UBM. To the best of our knowledge, because this is the first detection of V2 receptors in the mammalian bladder mucosa, we also probed human UBM for V2 receptors and observed high expression in human UBM. Unlike V1a and V2 receptors, aging had only a minor effect on plasma vasopressin levels (8% increase). CONCLUSIONS V2 receptors are substantially increased in the aging UBM. The role of these receptors in UBM is as yet undefined, but given their presence and action in the kidneys, the possible effect of these receptors in free water regulation should be considered. The large age-related increase in the expression of V2 receptors in both the UBM and kidney may contribute to the effectiveness of desmopressin in age-related nocturia.
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Oxidative stress induces release of 2'-AMP from microglia. Brain Res 2018; 1706:101-109. [PMID: 30395838 DOI: 10.1016/j.brainres.2018.11.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2018] [Revised: 10/31/2018] [Accepted: 11/02/2018] [Indexed: 11/18/2022]
Abstract
BACKGROUND Microglia metabolize exogenous 2'-AMP and 3'-AMP (non-canonical nucleotides) to adenosine and exogenous 2'-AMP and 3'-AMP (via conversion to adenosine) inhibit the production of inflammatory cytokines by microglia. This suggests that if microglia release endogenous 2'-AMP and/or 3'-AMP in response to injurious stimuli, this would complete an autocrine/paracrine mechanism that attenuates the over-activation of microglia during brain injury. Here we investigated in microglia (and for comparison astrocytes and neurons) the effects of injurious stimuli on extracellular and intracellular levels of 2',3'-cAMP (2'-AMP and 3'-AMP precursor), 2'-AMP, and 3'-AMP. METHODS Experiments were conducted in primary cultures of rat microglia, astrocytes, and neurons. Cells were exposed to oxygen/glucose deprivation, iodoacetate plus 2,4-dinitrophenol (metabolic inhibitors), glutamate, or H2O2 for one hour, and extracellular and intracellular 2',3'-cAMP, 2'-AMP, and 3'-AMP were measured by UPLC-MS/MS. KEY RESULTS In microglia, H2O2 increased extracellular levels of 2'-AMP, but not 3'-AMP, by ∼16-fold (from 0.17 ± 0.11 to 2.78 ± 0.27 ng/106 cells; n = 13; mean ± SEM; P < 0.000005). H2O2 also induced oxidative changes in cellular proteins as detected by an increased number of carbonyl groups in protein side chains. In contrast, oxygen/glucose deprivation, metabolic inhibitors, or glutamate had no effect on either extracellular 2'-AMP or 3'-AMP levels. In astrocytes and neurons, none of the injurious stimuli increased extracellular 2'-AMP or 3'-AMP. CONCLUSIONS Oxidative stress (but not oxygen/glucose deprivation, energy deprivation, or excitotoxicity) induces microglia (but not astrocytes or neurons) to release 2'-AMP, but not 3'-AMP. The 2',3'-cAMP/2'-AMP/adenosine pathway mechanism may serve to prevent over-activation of microglia in response to oxidative stress.
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Exosomes in HNSCC plasma as surrogate markers of tumour progression and immune competence. Clin Exp Immunol 2018; 194:67-78. [PMID: 30229863 DOI: 10.1111/cei.13157] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/13/2018] [Indexed: 12/22/2022] Open
Abstract
Exosomes in plasma of head and neck squamous cell carcinoma (HNSCC) patients comprise subsets of vesicles derived from various cells. Recently, we separated CD3(+) from CD3(-) exosomes by immune capture. CD3(-) exosomes were largely tumour-derived (CD44v3+ ). Both subsets carried immunosuppressive proteins and inhibited functions of human immune cells. The role of these subsets in immune cell reprogramming by the tumour was investigated by focusing on the adenosine pathway components. Spontaneous adenosine production by CD3(+) or CD3(-) exosomes was measured by mass spectrometry, as was the production of adenosine by CD4+ CD39+ regulatory T cells (Treg ) co-incubated with these exosomes. The highest level of CD39/CD73 ectoenzymes and of adenosine production was found in CD3(-) exosomes in patients with the stages III/IV HNSCCs). Also, the production of 5'-AMP and purines was significantly higher in Treg co-incubated with CD3(-) than CD3(+) exosomes. Consistently, CD26 and adenosine deaminase (ADA) levels were higher in CD3(+) than CD3(-) exosomes. ADA and CD26 levels in CD3(+) exosomes were significantly higher in patients with early (stages I/II) than advanced (stages III/IV) disease. HNSCC patients receiving and responding to photodynamic therapy had increased ADA levels in CD3(+) exosomes with no increase in CD3(-) exosomes. The opposite roles of CD3(+) ADA+ CD26+ and CD3(-) CD44v3+ adenosine-producing exosomes in early versus advanced HNSCC suggest that, like their parent cells, these exosomes serve as surrogates of immune suppression in cancer.
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Abstract 067: Mechanism of Action of 8-Aminoguanine on Renal Excretory Function. Hypertension 2018. [DOI: 10.1161/hyp.72.suppl_1.067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The endogenous purines 8-aminoguanosine and 8-aminoguanine (8-AG) are K
+
-sparing natriuretics that increase glucose excretion and attenuate salt-induced hypertension. Most effects of 8-aminoguanosine are not direct, but require conversion in the systemic circulation to 8-AG (i.e., 8-aminoguanosine is a prodrug/prohormone). However, the mechanism of action by which 8-AG affects renal excretory function is unknown and is the subject of this investigation. Because 8-AG has structural similarities with inhibitors of epithelial Na
+
channels (ENaC), Na
+
/H
+
exchangers (NHE), and adenosine A
1
receptors, we examined the effects of 8-AG on amiloride-sensitive ENaC activity in mouse collecting duct cells, on intracellular pH of human renal proximal tubule epithelial cells, and on in vivo (in rats) pharmacological responses to 2-chloro-N
6
-cyclopentyladenosine (A
1
-receptor agonist). 8-AG did not block ENaC, NHE, or A
1
receptors. Because Rac1 enhances activity of mineralocorticoid receptors and some guanosine analogues inhibit Rac1, we examined the effects of 8-AG on Rac1 activity in mouse collecting duct cells. Rac1 activity was significantly (
P
=0.024) inhibited by 8-AG (30 μM; from 2.5 ± 0.7 to 1.7 ± 0.7 arbitrary units). Because 8-AG is an inhibitor of purine nucleoside phosphorylase (PNPase; metabolizes inosine to hypoxanthine and guanosine to guanine), we compared the renal effects (in rats) of approximately equipotent intravenous doses of 8-AG (33.5 μmol/kg) vs. 9-deazaguanine (9-DG; 67 μmol/kg; PNPase inhibitor). 8-AG and 9-DG induced similar increases in urinary Na
+
(μmol/30 min; 8-AG, from 4.4 ± 2.0 to 38 ± 17; 9-DG, from 5.6 ± 3.3 to 34 ± 8.6) and glucose (μg/30 min; 8-AG, from 31 ± 17 to 225 ± 77; 9-DG, from 6.9 ± 3.9 to 144 ± 81) excretion. Intravenous 8-AG increased urinary excretion of guanosine and inosine (PNPase substrates), yet decreased excretion of guanine and hypoxanthine (PNPase products). 8-AG reduced K
+
excretion (μmol/30 min; 8-AG, from 29 ± 6.6 to 5.4 ± 1.7) whereas 9-DG did not. However, the Rac1 inhibitor Nsc23766 (9.4 μmol/kg) mimicked the effects of 8-AG on K
+
excretion (μmol/30 min; from 40 ± 7.1 to 18 ± 6.5). Conclusion: Likely 8-AG increases Na
+
and glucose excretion by blocking PNPase and decreases K
+
excretion by inhibiting Rac1.
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Adenosine Receptors Influence Hypertension in Dahl Salt-Sensitive Rats. Hypertension 2018; 72:511-521. [DOI: 10.1161/hypertensionaha.117.10765] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 01/03/2018] [Accepted: 05/09/2018] [Indexed: 12/27/2022]
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50
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Experimental intravascular hemolysis induces hemodynamic and pathological pulmonary hypertension: association with accelerated purine metabolism. Pulm Circ 2018; 8:2045894018791557. [PMID: 30003836 PMCID: PMC6080084 DOI: 10.1177/2045894018791557] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Pulmonary hypertension (PH) is emerging as a serious complication associated with
hemolytic disorders, and plexiform lesions (PXL) have been reported in patients
with sickle cell disease (SCD). We hypothesized that repetitive hemolysis per se
induces PH and angioproliferative vasculopathy and evaluated a new mechanism for
hemolysis-associated PH (HA-PH) that involves the release of adenosine deaminase
(ADA) and purine nucleoside phosphorylase (PNP) from erythrocytes. In healthy
rats, repetitive administration of hemolyzed autologous blood (HAB) for 10 days
produced reversible pulmonary parenchymal injury and vascular remodeling and PH.
Moreover, the combination of a single dose of Sugen-5416 (SU, 200 mg/kg) and
10-day HAB treatment resulted in severe and progressive obliterative PH and
formation of PXL (Day 26, right ventricular peak systolic pressure (mmHg):
26.1 ± 1.1, 41.5 ± 0.5 and 85.1 ± 5.9 in untreated, HAB treated and SU+HAB
treated rats, respectively). In rats, repetitive administration of HAB increased
plasma ADA activity and reduced urinary adenosine levels. Similarly, SCD
patients had higher plasma ADA and PNP activity and accelerated adenosine,
inosine, and guanosine metabolism than healthy controls. Our study provides
evidence that hemolysis per se leads to the development of angioproliferative
PH. We also report the development of a rat model of HA-PH that closely mimics
pulmonary vasculopathy seen in patients with HA-PH. Finally, this study suggests
that in hemolytic diseases released ADA and PNP may increase the risk of PH,
likely by abolishing the vasoprotective effects of adenosine, inosine and
guanosine. Further characterization of this new rat model of hemolysis-induced
angioproliferative PH and additional studies of the role of purines metabolism
in HA-PH are warranted.
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