{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,29]],"date-time":"2026-04-29T20:31:57Z","timestamp":1777494717438,"version":"3.51.4"},"reference-count":39,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2025,7,27]],"date-time":"2025-07-27T00:00:00Z","timestamp":1753574400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Life"],"abstract":"<jats:p>Background: Cerebral aneurysm (CA) is a focal or diffuse pathological dilation of the cerebral arterial wall that arises due to various etiological factors. It represents a serious vascular condition, particularly affecting the elderly, and carries a high risk of rupture and neurological morbidity. Clonidine (CL), an \u03b12-adrenergic receptor agonist, has been reported to suppress aneurysm progression; however, its underlying molecular mechanisms, especially in relation to cerebral endothelial dysfunction, remain unclear. This study aimed to investigate the potential of CL to mitigate CA development by modulating apoptosis, inflammation, and oxidative stress in an Angiotensin II (Ang II)-induced endothelial injury model. Methods: Human brain microvascular endothelial cells (HBMECs) were used to establish an in vitro model of endothelial dysfunction by treating cells with 1 \u00b5M Ang II for 48 h. CL was administered 2 h prior to Ang II exposure at concentrations of 0.1, 1, and 10 \u00b5M. Cell viability was assessed using the MTT assay. Oxidative stress markers, including reactive oxygen species (ROS) and Nitric Oxide (NO), were measured using 2\u2032,7\u2032\u2013dichlorofluorescin diacetate (DCFDA). Gene expression levels of vascular endothelial growth factor (VEGF), matrix metalloproteinases (MMP-2 and MMP-9), high mobility group box 1 (HMGB1), and nuclear factor kappa B (NF-\u03baB) were quantified using RT-qPCR. Levels of proinflammatory cytokines; tumor necrosis factor-alpha (TNF-\u03b1), Interleukin-6 (IL-6), and interferon-gamma (IFN-\u03b3); were measured using commercial ELISA kits. Results: Ang II significantly increased ROS production and reduced NO levels, accompanied by heightened proinflammatory cytokine release and endothelial dysfunction. MTT assay revealed a marked decrease in cell viability following Ang II treatment (34.18%), whereas CL preserved cell viability in a concentration-dependent manner: 44.24% at 0.1 \u00b5M, 66.56% at 1 \u00b5M, and 81.74% at 10 \u00b5M. CL treatment also significantly attenuated ROS generation and inflammatory cytokine levels (p &lt; 0.05). Furthermore, the expression of VEGF, HMGB1, NF-\u03baB, MMP-2, and MMP-9 was significantly downregulated in response to CL. Conclusions: CL exerts a protective effect on endothelial cells by reducing oxidative stress and suppressing proinflammatory signaling pathways in Ang II-induced injury. These results support the potential of CL to mitigate endothelial injury in vitro, though further in vivo studies are required to confirm its translational relevance.<\/jats:p>","DOI":"10.3390\/life15081193","type":"journal-article","created":{"date-parts":[[2025,7,28]],"date-time":"2025-07-28T07:57:24Z","timestamp":1753689444000},"page":"1193","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Clonidine Protects Endothelial Cells from Angiotensin II-Induced Injury via Anti-Inflammatory and Antioxidant Mechanisms"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0875-6147","authenticated-orcid":false,"given":"Bekir S\u0131tk\u0131 Said","family":"Ulusoy","sequence":"first","affiliation":[{"name":"Department of Interventional Radiology, University of Health Sciences, Gaziantep City Hospital, 27470 Gaziantep, Turkey"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7317-5467","authenticated-orcid":false,"given":"Mehmet Cudi","family":"Tuncer","sequence":"additional","affiliation":[{"name":"Department of Anatomy, Faculty of Medicine, Dicle University, 21280 Diyarbakir, Turkey"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"\u0130lhan","family":"\u00d6zdemir","sequence":"additional","affiliation":[{"name":"Department of Gynecology and Obstetrics, Faculty of Medicine, Atat\u00fcrk University, 25030 Erzurum, Turkey"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,7,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Wang, X., and Huang, X. (2024). Risk factors and predictive indicators of rupture in cerebral aneurysms. Front. Physiol., 15.","DOI":"10.3389\/fphys.2024.1454016"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Wu, A., Zhao, C., Mou, S., Li, S., Cui, X., and Zhang, R. (2022). Integrated analysis identifies the IL6\/JAK\/STAT signaling pathway and the estrogen response pathway associated with the pathogenesis of intracranial aneurysms. Front. Immunol., 13.","DOI":"10.3389\/fimmu.2022.1046765"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Morel, S., Schilling, S., Diagbouga, M.R., Delucchi, M., Bochaton-Piallat, M.L., Lemeille, S., Hirsch, S., and Kwak, B.R. (2021). Effects of Low and High Aneurysmal Wall Shear Stress on Endothelial Cell Behavior: Differences and Similarities. Front. Physiol., 12.","DOI":"10.3389\/fphys.2021.727338"},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"N\u00e1dasy, G.L., Balla, A., D\u00f6rnyei, G., Hunyady, L., and Szekeres, M. (2024). Direct Vascular Effects of Angiotensin II (A Systematic Short Review). Int. J. Mol. Sci., 26.","DOI":"10.3390\/ijms26010113"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1085","DOI":"10.1089\/ars.2012.4604","article-title":"Angiotensin II-induced production of mitochondrial reactive oxygen species: Potential mechanisms and relevance for cardiovascular disease","volume":"19","author":"Dikalov","year":"2013","journal-title":"Antioxid. Redox Signal."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"976","DOI":"10.1007\/s00380-018-1315-1","article-title":"Disease-specific characteristics of vascular cell adhesion molecule-1 levels in patients with peripheral artery disease","volume":"34","author":"Edlinger","year":"2019","journal-title":"Heart Vessels"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"553","DOI":"10.1097\/FJC.0b013e31827303fa","article-title":"The effect of clonidine, an alpha-2 adrenergic receptor agonist, on inflammatory response and postischemic endothelium function during early reperfusion in healthy volunteers","volume":"60","author":"Gourdin","year":"2012","journal-title":"J. Cardiovasc. Pharmacol."},{"key":"ref_8","first-page":"252","article-title":"Clonidine Induces Apoptosis of Human Corneal Epithelial Cells through Death Receptors-Mediated, Mitochondria-Dependent Signaling Pathway","volume":"156","author":"Fan","year":"2017","journal-title":"Toxicol. Sci."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"214","DOI":"10.2176\/nmc.ra.2014-0337","article-title":"Molecular mechanisms of the formation and progression of intracranial aneurysms","volume":"55","author":"Kataoka","year":"2015","journal-title":"Neurol. Med. Chir."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"55","DOI":"10.1016\/0022-1759(83)90303-4","article-title":"Rapid colorimetric assay for cellular growth and survival: Application to proliferation and cytotoxicity assays","volume":"65","author":"Mosmann","year":"1983","journal-title":"J. Immunol. Methods"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"62","DOI":"10.1006\/niox.2000.0319","article-title":"A rapid, simple spectrophotometric method for simultaneous detection of nitrate and nitrite","volume":"5","author":"Miranda","year":"2001","journal-title":"Nitric Oxide"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"829","DOI":"10.1093\/eurheartj\/ehr304","article-title":"Nitric oxide synthases: Regulation and function","volume":"33","author":"Sessa","year":"2012","journal-title":"Eur. Heart J."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"7251","DOI":"10.1007\/s11033-021-06719-w","article-title":"Prunetin inhibits nitric oxide activity and induces apoptosis in urinary bladder cancer cells via CASP3 and TNF-\u03b1 genes","volume":"48","author":"Nalbantsoy","year":"2021","journal-title":"Mol. Biol. Rep."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"20","DOI":"10.1038\/sj.jhh.1002101","article-title":"Angiotensin II and inflammation: The effect of angiotensin-converting enzyme inhibition and angiotensin II receptor blockade","volume":"21","author":"Dandona","year":"2007","journal-title":"J. Hum. Hypertens."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"781","DOI":"10.1007\/s10571-009-9368-4","article-title":"Anti-inflammatory effects of angiotensin receptor blockers in the brain and the periphery","volume":"29","author":"Benicky","year":"2009","journal-title":"Cell Mol. Neurobiol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"E10","DOI":"10.3171\/2019.4.FOCUS19204","article-title":"Genetic basis of intracranial aneurysm formation and rupture: Clinical implications in the postgenomic era","volume":"47","author":"Samuel","year":"2019","journal-title":"Neurosurg. Focus"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"31","DOI":"10.2344\/0003-3006-62.1.31","article-title":"Alpha-2 adrenergic receptor agonists: A review of current clinical applications","volume":"62","author":"Giovannitti","year":"2015","journal-title":"Anesth. Prog."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Atkinson, G., Bianco, R., Di Gregoli, K., and Johnson, J.L. (2023). The contribution of matrix metalloproteinases and their inhibitors to the development, progression, and rupture of abdominal aortic aneurysms. Front. Cardiovasc. Med., 10.","DOI":"10.3389\/fcvm.2023.1248561"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Golombek, S., Doll, I., Kaufmann, L., Lescan, M., Schlensak, C., and Avci-Adali, M. (2024). A Novel Strategy for the Treatment of Aneurysms: Inhibition of MMP-9 Activity through the Delivery of TIMP-1 Encoding Synthetic mRNA into Arteries. Int. J. Mol. Sci., 25.","DOI":"10.3390\/ijms25126599"},{"key":"ref_20","first-page":"3209","article-title":"Tizanidine exerts anti-nociceptive effects in spared nerve injury model of neuropathic pain through inhibition of TLR4\/NF-\u03baB pathway","volume":"42","author":"Pei","year":"2018","journal-title":"Int. J. Mol. Med."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"168","DOI":"10.1038\/s41392-023-01430-7","article-title":"Signaling pathways in vascular function and hypertension: Molecular mechanisms and therapeutic interventions","volume":"8","author":"Ma","year":"2023","journal-title":"Signal Transduct. Target. Ther."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1373","DOI":"10.1002\/j.2040-4603.2021.tb00152.x","article-title":"Baroreceptor Modulation of the Cardiovascular System, Pain, Consciousness, and Cognition","volume":"11","author":"Mamoun","year":"2021","journal-title":"Compr. Physiol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1873","DOI":"10.1007\/s00134-024-07619-w","article-title":"Low-dose clonidine infusion to improve sleep in postoperative patients in the high-dependency unit. A randomised placebo-controlled single-centre trial","volume":"50","author":"Liu","year":"2024","journal-title":"Intensive Care Med."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"163","DOI":"10.3390\/oxygen3020012","article-title":"Mechanisms of Mitochondrial Oxidative Stress in Brain Injury: From Pathophysiology to Therapeutics","volume":"3","author":"Nguyen","year":"2023","journal-title":"Oxygen"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1659","DOI":"10.1038\/jcbfm.2012.84","article-title":"Biology of intracranial aneurysms: Role of inflammation","volume":"32","author":"Chalouhi","year":"2012","journal-title":"J. Cereb. Blood Flow Metab."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1007\/978-3-319-04981-6_2","article-title":"Molecular basis for intracranial aneurysm formation","volume":"120","author":"Fukuda","year":"2015","journal-title":"Acta Neurochir. Suppl."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1237","DOI":"10.1111\/j.1476-5381.2011.01358.x","article-title":"PGE(2) -EP(2) signalling in endothelium is activated by haemodynamic stress and induces cerebral aneurysm through an amplifying loop via NF-\u03baB","volume":"163","author":"Aoki","year":"2011","journal-title":"Br. J. Pharmacol."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Fennell, V.S., Kalani, M.Y., Atwal, G., Martirosyan, N.L., and Spetzler, R.F. (2016). Biology of saccular cerebral aneurysms: A review of current understanding and future directions. Front. Surg., 3.","DOI":"10.3389\/fsurg.2016.00043"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"2594","DOI":"10.1161\/STROKEAHA.113.002361","article-title":"Localized increase of chemokines in the lumen of human cerebral aneurysms","volume":"44","author":"Chalouhi","year":"2013","journal-title":"Stroke"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"402","DOI":"10.1186\/s13054-019-2690-4","article-title":"The effect of dexmedetomidine and clonidine on the inflammatory response in critical illness: A systematic review of animal and human studies","volume":"23","author":"Flanders","year":"2019","journal-title":"Crit. Care"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"263","DOI":"10.1038\/s41440-018-0016-6","article-title":"Co-treatment with clonidine and a GRK2 inhibitor prevented rebound hypertension and endothelial dysfunction after withdrawal in diabetes","volume":"41","author":"Taguchi","year":"2018","journal-title":"Hypertens. Res."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"191","DOI":"10.1007\/s11906-006-0050-7","article-title":"Inflammation and the metabolic syndrome: Role of angiotensin II and oxidative stress","volume":"8","author":"Ferder","year":"2006","journal-title":"Curr. Hypertens. Rep."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"1257","DOI":"10.1161\/01.ATV.0000021412.56621.A2","article-title":"Vascular inflammation and the renin-angiotensin system","volume":"22","author":"Brasier","year":"2002","journal-title":"Arterioscler. Thromb. Vasc. Biol."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"55S","DOI":"10.1016\/S0895-7061(01)02070-2","article-title":"Modulating angiotensin II-induced inflammation by HMG Co-A reductase inhibition","volume":"14","author":"Dechend","year":"2001","journal-title":"Am. J. Hypertens."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1227\/NEU.0b013e3182770e8c","article-title":"Oxidative stress is associated with cell death, wall degradation, and increased risk of rupture of the intracranial aneurysm wall","volume":"72","author":"Laaksamo","year":"2013","journal-title":"Neurosurgery"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"247","DOI":"10.2174\/15672026113109990003","article-title":"The role of oxidative stress in cerebral aneurysm formation and rupture","volume":"10","author":"Starke","year":"2013","journal-title":"Curr. Neurovasc. Res."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"269","DOI":"10.1007\/s12975-013-0287-9","article-title":"Tumor necrosis factor-\u03b1 modulates cerebral aneurysm formation and rupture","volume":"5","author":"Starke","year":"2014","journal-title":"Transl. Stroke Res."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"185","DOI":"10.1186\/s12974-019-1568-3","article-title":"Nrf-2 signaling inhibits intracranial aneurysm formation and progression by modulating vascular smooth muscle cell phenotype and function","volume":"16","author":"Shi","year":"2019","journal-title":"J. Neuroinflamm."},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Zhang, J., Duan, P., Nie, B., Zhang, Z., Shi, R., Liu, Q., Wang, S., Xu, T., and Tian, J. (2024). Identification and Verification of the Oxidative Stress-Related Signature Markers for Intracranial Aneurysm-Applied Bioinformatics. Front. Biosci. Landmark Ed., 29.","DOI":"10.31083\/j.fbl2908294"}],"container-title":["Life"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2075-1729\/15\/8\/1193\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T18:17:00Z","timestamp":1760033820000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2075-1729\/15\/8\/1193"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,7,27]]},"references-count":39,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2025,8]]}},"alternative-id":["life15081193"],"URL":"https:\/\/doi.org\/10.3390\/life15081193","relation":{},"ISSN":["2075-1729"],"issn-type":[{"value":"2075-1729","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,7,27]]}}}