angiotensin-i and Carotid-Stenosis

Clinical trials have demonstrated that agents that inhibit the angiotensin II pathway confer benefit beyond the reduction of blood pressure alone. However, the molecular mechanism underlying this effect has yet to be investigated. Recently, we have demonstrated enhanced expression of inducible cyclooxygenase (COX) and prostaglandin (PG)E2-dependent synthase (COX-2/mPGES-1) in human symptomatic plaques and provided evidence that it is associated with metalloproteinase (MMP)-induced plaque rupture. Thus, the aim of this study was to characterize the effect of the angiotensin II type 1 (AT1) receptor antagonist irbesartan on the inflammatory infiltration and expression of COX-2/mPGES-1 and MMPs in human carotid plaques.. Seventy patients with symptomatic carotid artery stenosis were randomized to irbesartan (300 mg/d) or chlorthalidone (50 mg/d) for 4 months before endarterectomy. Plaques were subjected to analysis of COX-1, COX-2, mPGES-1, MMP-2, and MMP-9, angiotensin II, AT(1), AT2, and collagen content by immunocytochemistry, Western blot, and reverse-transcriptase polymerase chain reaction, whereas zymography was used to detect MMP activity. Immunohistochemistry was also used to identify CD68+ macrophages, CD3+ T lymphocytes, smooth muscle cells (SMCs), and HLA-DR+ inflammatory cells. Plaques from the irbesartan group had fewer (P<0.0001) macrophages, T lymphocytes, and HLA-DR+ cells; less (P<0.0001) immunoreactivity for COX-2/mPGES-1 and MMPs; reduced (P<0.0001) gelatinolytic activity; and increased (P<0.0001) collagen content. It is worth noting that COX-2/mPGES-1 inhibition was observed after incubation in vitro with irbesartan but not with the selective AT2 blockade PD123,319.. This study demonstrates that irbesartan decreases inflammation and inhibits COX-2/mPGES-1 expression in plaque macrophages, and this effect may in turn contribute to plaque stabilization by inhibition of MMP-induced plaque rupture.

Topics: Aged; Angiotensin I; Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Antihypertensive Agents; Biphenyl Compounds; Carotid Artery, Internal; Carotid Stenosis; Chlorthalidone; Collagen; Combined Modality Therapy; Cyclooxygenase 1; Cyclooxygenase 2; Depression, Chemical; Dinoprostone; Endarterectomy, Carotid; Enzyme Induction; Extracellular Matrix; Female; Gene Expression Regulation; Humans; Inflammation; Intramolecular Oxidoreductases; Irbesartan; Isoenzymes; Macrophages; Male; Matrix Metalloproteinase Inhibitors; Membrane Proteins; Prostaglandin-E Synthases; Prostaglandin-Endoperoxide Synthases; Protease Inhibitors; Rupture, Spontaneous; Tetrazoles

Milan hypertensive rats (MHS) are characterised by an increase in renal sodium reabsorption mainly related to adducin mutations. Interest in this model relies on the genetic link between adducin polymorphisms and primary hypertension, observed also in a subset of patients.. To investigate the molecular and morphological events involved in carotid stenosis and triggered by surgery in MHS model.. Stenosis was induced through arteriotomy. At different times after injury, the expression profiles of various gene families were investigated by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR), while histological techniques were used to follow morphometric and morphological changes. Apoptotic nuclei were revealed by terminal deoxynucleotidyl transferase-dUTP nick end labelling (TUNEL).. mRNAs coding for transcription factors c-jun, c-fos and c-myc were rapidly induced by injury. Analysis of apoptosis-related genes revealed a decrease of the Bcl-2/Bax ratio 4 h after vascular trauma (P<0.05), followed by a recovery of antiapoptotic factors 24 and 48 h later. ET(A) and receptor mRNAs decreased after the injury and were replaced by ET(B) and AT2 mRNAs. Both ET(A) and AT1 turned to basal level 48 h after injury. Expression profiles of chatepsins B and D were also determined. A marked neoadventitia led to maximal 60+/-9% lumen reduction (P<0.05) 30 days after surgery. Media substitution by fibrotic and granulomatous tissue was also evident. Maximal 47+/-2% apoptotic nuclei were detected 48 h after the injury (P<0.05).. The injury applied to MHS carotids induces negative remodelling and a limited apoptotic reaction. These findings could arise from the balancing among proliferative factors, apoptosis-related molecules and relaxant anti-proliferative receptors, all stimulated by the injury.

Topics: Angiotensin I; Angiotensin II; Animals; Apoptosis; Carotid Arteries; Carotid Stenosis; Disease Progression; Gene Expression; Genes, fos; Genes, jun; Genes, myc; Hypertension; Models, Animal; Rats; Rats, Inbred Strains; Receptor, Endothelin A; Receptor, Endothelin B; RNA, Messenger