Quantitation of Perivascular Monocytes and Macrophages around Cerebral Blood Vessels of Hypertensive and Aged Rats

Abstract

Summary: The numbers of monocytes and macrophages in the walls of cerebral blood vessels were counted on perfusion-fixed frozen brain sections (16 fLm) of sponta neously hypertensive rats (SHR), stroke-prone SHR (SHR-SP), normotensive Wistar-Kyoto (WKY) rats, and young (16-week-old) and old (2-year-old) normotensive Sprague-Dawley rats (SD-16w and SD-2y, respectively) using monoclonal antibodies against rat macrophages (ED2). The staining was visualized with fluorescein labeled second antibodies. The ED2-specific staining in brain sections was restricted to macrophages in a peri vascular location. The number of perivascular cells per square millimeter of high-power field was significantly greater in SHR-SP (8.6 ± 2.1; n = 4) and SHR (6.7 ± 0.9; n = 6) than in normotensive WKY (4.0 ± 0.5; n = 6; P <We have been interested in the possibility that, in individuals with risk factors for stroke, chronic ac tivation of monocytes and macrophages and/or en dothelium promotes a perivascular accumulation of monocytes and macrophages and an intensified cy- ANOV A, analysis of variance; ED2, monoclonal antibodies against rat macrophages; FITC, fluorescein isothiocyanate; FVlII-RA, factor VIII-related antigen; MHC, major histocom patibility complex; PBS, phosphate-buffered saline; SD-2y, 2-year-old Sprague-Dawley rats; SD-16w, 16-week-old Sprague Dawley rats; SHR, spontaneously hypertensive rats; SHR-SP, stroke-prone spontaneously hypertensive rats; TNF-a, tumor necrosis factor-a; WKY, Wistar-Kyoto. 3480.01). The number of perivascular macrophages was also greater in SD-2y (7.5 ± 2.7; n = 9) than in SD-16w (2.9 ± 1.8; n = 8; P < 0.01). No ED2 staining was found in the resident microglia or in the endothelial cells, which were identified by double staining with rhodamine-labeled anti-factor VIII-related antigen antibodies. The results suggest that the stroke risk factors hypertension and ad vanced age are associated with increased subendothelial accumulation of monocytes and macrophages. This accu mulation could increase the tendency for the endothelium to convert from an anticoagulant to a procoagulant sur face in response to mediators released from these suben dothelial cells. Key Words: Immunofluorescence-ED2-Von Willebrand factor-Rats-Brain.

Comparison of tumour necrosis factor and endothelin-1 between essential and renal hypertensive patients

“…6,7,24,25 TNF␣ enhances the expression of intercellular adhesion molecule-1 (ICAM-1) 9 and blood levels of ICAM-1 were found to be increased in atherosclerotic hypertensive subjects with preserved renal function, suggesting a systemic endothelial dysfunction. 26 Furthermore, on the basis of experimental results Liu et al 27,28 hypothesised that in hypertension, vascular thrombotic risk is associated with Table 1 Mean age, serum creatinine and creatinine clearance (Clcr), blood levels of TNF␣ and ET-1, UAE, 24-h systolic-(SBP), diastolic (DBP) and mean (MBP) blood pressures in normotensive controls (NT), in patients with essential hypertension (EH), and in hypertensive subjects with renal insufficiency (CRF)…”

Angiotensin II AT 1 Receptor Blockade Reverses Pathological Hypertrophy and Inflammation in Brain Microvessels of Spontaneously Hypertensive Rats

“…Similar alterations in macrophage adherence and infiltration were reported in microvessels during experimental autoimmune encephalomyelitis, 31 after injection of ink particles into the perivascular spaces, 32 and in hypertensive and aged rats. 33 AT 1 receptor blockade reverses these alterations and reduces pathological hypertrophy not only in large vessels but also in cerebral microvessels. Our results agree with an electron microscopy study reporting a decrease in perivascular macrophages in SHR after AT 1 receptor blockade 34 and indicate that AT 1 receptor blockade normalizes the brain microcirculation and, as a consequence, decreases the vulnerability to brain ischemia and stroke in chronically hypertensive rats.…”

Monocyte adhesion to cerebromicrovascular endothelial cells derived from hypertensive and normotensive rats

“…Enhanced monocyte interaction with endothelium in segments of the vasculature may signify the ease at which overall disturbances of endothelium can occur. This increased sensitivity of SHR EC may represent a mechanism by which hypertension acts as a predisposing factor for the development of thrombotic vascular disease (13,15,26).…”

“…These findings may indicate a mechanism at least partially responsible for increases in in vivo perivascular monocyte accumulation seen in hypertensive rats (15,27). Some of these effects may be mediated by the production of proinflammatory factors such as TNFa, which is produced in greater amounts by SHR than by WKY rats when injected with LPS (26,27).…”