C3a and C5a anaphylatoxins are two proinflammatory peptides generated during complement activation that act through distinct G i protein-coupled receptors named C3aR and C5aR, respectively. We have demonstrated previously that human astrocytes expressed C3aR and C5aR constitutively and were able to produce a functional complement. In this study, we examined the effect of an anaphylatoxin stimulation on cytokine expression by human astrocyte cell lines. Interleukin (IL)-1␤,

No abstract

Human astrocyte cell lines reportedly contain a specific receptor for the complement anaphylatoxin C3a based on ligand‐binding studies, functional responses, and RNA analysis by RT‐PCR. Uptake of 125I‐C3a by astrocytes was specific and reversible. Scatchard analysis indicated the presence of two classes of binding sites. High‐affinity binding sites were abundantly expressed (20,000–80,000 sites per cell) with an estimated KD of 1–2 nM. Low‐affinity binding sites with a KD of 209 nM were largely expressed (n≥ 4 × 106 sites per cell) and probably did not reflect a receptor‐mediated binding, but rather an ionic interaction between C3a and the membrane. Analysis of astrocyte mRNA by RT‐PCR with three different sets of primers covering 60% of the C3a receptor (C3aR) mRNA sequence indicated that glial C3aR was identical to the leukocytic one. Western blot analysis using a specific anti‐C3aR evidenced a C3aR with a molecular mass of 60,000 Da. C3a and a superagonist peptide, E7, induced a transient increase of intracellular [Ca2+] in primary culture of astrocytes. Treatment of the ligands by carboxypeptidase B to eliminate the C‐terminus Arg considerably decreased the [Ca2+] response. Moreover, flow cytometry experiments demonstrated the expression of C3aR on normal rat astrocyte membrane. This report brings new insight for the role of the complement system in the brain inflammation response.

Spontaneously hypertensive Okamoto-strain rats (SHR) and normotensive Wistar-Kyoto (WKY) rats were actively immunizedwith mouse renin to investigate the effect on blood pressure of blocking the renin-angiotensinogen reaction. Ten male SHR and 10 male WKY rats were immunizedwith purified mouse submandibular gland renin. Control rats were immunized with bovine serum albumin. Antirenin antibodies were produced by both SHR andWKY rats, but renin-immunized SHR had higher titers of circulating renin antibodies after three injections. The increase in renin antibody in renin-immunized SHR was associated with a significant drop in blood pressure (tail-cuff method) that became similar to that of theWKY control rats after four injections. The blockade by antirenin immunoglobulins of the renin-angiotensinogen reaction also decreased the blood pressure of normotensive rats. Perfusion of renin-immunized rats with mouse submandibular renin (10,g) in vivo caused no increase in blood pressure. Perfusion of renin-immunized, salt-depleted SHR with converting enzyme inhibitor caused no further decrease in blood pressure but significantly decreased blood pressure in salt-depleted control rats. The presence of circulating renin antibodies was associated with low plasma renin activity (0.31±0.23 ng angiotensin I [Ang I]/ml/hr). Plasma renin activity was unchanged in control animals (13.1±3.9 ng Ang ImlI/hr in control SHR, 13.9±3.2 ng Ang VImlIhr in control WKY rats). Renin antibody-rich serum produced a dose-dependent inhibition of rat renin enzymatic activity in vitro. The chronic blockade of the renin-angiotensinogen reaction in renin-immunized SHR produced an almostcomplete disappearance of Ang 11 (0.8±7fmol/ml; control SHR, 30.6±+15.7 fmol/ml) and a 50%o reduction in urinary aldosterone. Renin immunization was never associated with a detectable loss of sodium after either 10 or 24 weeks. The glomerular filtration rate was not decreased 10 weeks after renin immunization, whereas blood pressure was significantly decreased, plasma renin activity was blocked, and renal plasma flow was increased. The ratio of left ventricular weight to body weight after 24 weeks was significantly below control levels in renin-immunized WKY rats and SHR. Histological examination of the kidney of renin-immunized SHR showed a chronic autoimmune interstitial nephritis characterized by the presence of immunoglobulins, mononuclear cell infiltration, and fibrosis around the juxtaglomerular apparatus. These expenments demonstrate that chronic specific blockade of renin decreases blood pressure in a genetic model of hypertension in which the renin-angiotenisn system is not directly involved. It also offers a model for comparing chronic renin inhibition with other methods of blocking the renin-angiotensin system in the hypertensive rat. (Circulation 1990;81:1899-1910 T he most specific way to block the reninangiotensinogen. The renin-angiotensinogen reacangiotensin system is to inhibit its first and tion can be inhibited by passive administration of rate-limitin...

1 We investigated the role of arachidonic acid metabolism and assessed the participation of mast cells and leukocytes in neurogenic in¯ammation in rat paw skin. We compared the eect of lipoxygenase (LOX) and cyclo-oxygenase (COX) inhibitors on oedema induced by saphenous nerve stimulation, substance P (SP), and compound 48/80. 2 Intravenous (i.v.) pre-treatment with a dual COX/LOX inhibitor (RWJ 63556), a dual LOX inhibitor/cysteinyl-leukotriene (CysLt) receptor antagonist (Rev 5901), a LOX inhibitor (AA 861), a ®ve-lipoxygenase activating factor (FLAP) inhibitor (MK 886), or a glutathione S-transferase inhibitor (ethacrynic acid) signi®cantly inhibited (40 to 60%) the development of neurogenic oedema, but did not aect cutaneous blood¯ow. Intradermal (i.d.) injection of LOX inhibitors reduced SP-induced oedema (up to 50% for RWJ 63556 and MK 886), whereas ethacrynic acid had a potentiating eect. 3 Indomethacin and rofecoxib, a highly selective COX-2 inhibitor, did not aect neurogenic and SP-induced oedema. Surprisingly, the structurally related COX-2 inhibitors, NS 398 and nimesulide, signi®cantly reduced both neurogenic and SP-induced oedema (70% and 42% for neurogenic oedema, respectively; 49% and 46% for SP-induced oedema, respectively). 4 COX-2 mRNA was undetectable in saphenous nerves and paw skin biopsy samples, before and after saphenous nerve stimulation. 5 A mast cell stabilizer, cromolyn, and a H 1 receptor antagonist, mepyramine, signi®cantly inhibited neurogenic (51% and 43%, respectively) and SP-induced oedema (67% and 63%, respectively). 6 The co-injection of LOX inhibitors and compound 48/80 did not alter the eects of compound 48/80. Conversely, ethacrynic acid had a signi®cant potentiating eect. The pharmacological pro®le of the eect of COX inhibitors on compound 48/80-induced oedema was similar to that of neurogenic and SP-induced oedema. 7 The polysaccharide, fucoidan (an inhibitor of leukocyte rolling) did not aect neurogenic or SPinduced oedema. 8 Thus, (i) SP-induced leukotriene synthesis is involved in the development of neurogenic oedema in rat paw skin; (ii) this leukotriene-mediated plasma extravasation might be independent of mast cell activation and/or of the adhesion of leukocytes to the endothelium; (iii) COX did not appear to play a signi®cant role in this process.