BACKGROUND: Glomerular accumulation of macrophages/monocytes (M/M) is a typical early feature in the course of anti-thymocyte serum (ATS)-induced nephritis. We have previously shown that glomerular synthesis and expression of monocyte-chemoattractant protein-1 (MCP-1) occurs before influx of M/M and a neutralizing anti-MCP-1 antibody reduced this cell infiltrate by one third. The present study was undertaken to test the effect of two angiotensin II type 1 (AT1) receptor antagonists, losartan and irbesartan, on ATS-stimulated MCP-1 expression as well as glomerular influx of M/M. METHODS: Treatment of rats with either losartan or irbesartan was started 24 h before administration of ATS. After 24 h, MCP-1 mRNA expression was evaluated by RT-PCR and Northern blots. MCP-1 protein was determined by Western blots and chemotactic factors released from isolated glomeruli were measured by chemotactic assay. Kidney sections were stained for rabbit IgG, complement C3, and M/M (ED1 antigen). RESULTS: Both AT1-receptor antagonists caused a significant, but not total reduction in MCP-1 mRNA and protein expression 24 h after injection of ATS. Treatment with losartan or irbesartan also reduced the chemotactic activity of isolated glomeruli from nephritic animals. Quantification of ED1-positive cells revealed that losartan as well as irbesartan reduced glomerular M/M invagination in nephritic rats by approximately 30-50%. However, treatment with AT1-receptor antagonists did not influence binding of ATS to mesangial cells and subsequent complement activation indicating that the attenuated MCP-1 expression is not due to differences in delivery and binding of ATS to mesangial cells. CONCLUSION: Our data indicate that short-term antagonism of AT1 receptors abolished the early glomerular MCP-1 expression and M/M influx. These results indicate that angiotensin II may exert immunomodulatory effects in vivo and adds a new mechanism showing how this vasopeptide may be involved in the pathogenesis of renal diseases.

Angiotensin Receptor Antagonists↗

PubMedDate not supplied

Intrarenal arteries in rats with early two-kidney, one clip hypertension.

Structural arterial adaptation and decompensation were studied in the contralateral untouched kidneys of two-kidney, one clip hypertensive rats 1 to 64 days after constricting one renal artery. Focal necroses of intrarenal arteries were observed as early as 24 hours after starting the experiment. The necroses reached their maximum on Day 8 and thereafter decreased significantly in spite of still increasing blood pressure values. After 8 days the media thickness of the interlobular arteries was significantly increased by more than 30% and remained so until the end of the experiment. Blood pressure levels as measured by tail plethysmography were nearly normal within the first 4 days. The continuous 24-hour blood pressure recording in the conscious rats, however, showed shortlasting intermittent hypertensive spikes as early as 6 hours after renal artery constriction. In spite of these acute hypertensive peaks, which frequently exceeded 200 mm Hg, intimal lesions, potentially leading to malignant nephrosclerosis, began to appear after only 2 weeks. Thus, the development of nonobliterating, acute focal necroses of intrarenal arteries in the earliest stage of two-kidney, one clip hypertension may be explained by intermittent hypertensive episodes accompanied by a segmental overstretching of the nonadapted vascular bed. On the other hand, the occurrence of obliterating malignant nephrosclerosis in the presence of severe hypertension may also depend on the previously changed composition of the vessel walls.

Animals↗

PubMedDate not supplied

[Goodpasture's syndrome with atypical renal findings].

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Adult↗