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Somatostatin analog lanreotide inhibits myocyte replication and several growth factors in allograft arteriosclerosis
P Häyry1, A Räisänen, J Ustinov
1Transplantation Laboratory, University of Helsinki, Finland.
Abstract:
Chronic rejection is the most common reason for late loss of a transplant. The molecular mechanism of chronic rejection is not known and there is no treatment for this disorder. The characteristic histological feature in chronic rejection is increased smooth muscle cell replication in the vascular wall, leading to allograft arteriosclerosis. In this study we demonstrate that nonimmunosuppressed rat aortic allografts undergoing chronic rejection synthesize increased quantities of several smooth muscle cell growth-promoting substances in the vascular wall including interleukin-1, eicosanoids, and several peptide growth factors. Administration of a stable somatostatin analog lanreotide, BIM 23014, strongly inhibits myocyte proliferation in the allograft in vivo. It has no inhibitory effect on the proliferation of smooth muscle cells in vitro. Concomitantly, the locally produced peptide growth factors, i.e., epidermal growth factor, insulin-like growth factor 1, and BB-isomer of platelet-derived growth factor, but not other mediators of inflammation, are significantly reduced. The results suggest that growth factors are the main effector molecules leading to myocyte proliferation in allograft arteriosclerosis and that allograft arteriosclerosis (chronic rejection) may be specifically inhibited by lanreotide administration.
Insights
Chronic rejection, a major cause of transplant failure, involves smooth muscle cell proliferation. A somatostatin analog, lanreotide, effectively inhibits this proliferation by reducing growth factors, offering a potential treatment for allograft arteriosclerosis.
Area of Science:
- Transplantation immunology
- Vascular biology
- Molecular medicine
Background:
- Chronic rejection is the primary cause of late transplant loss.
- The underlying molecular mechanisms and effective treatments remain unknown.
- Allograft arteriosclerosis, characterized by vascular smooth muscle cell proliferation, is a hallmark of chronic rejection.
Purpose of the Study:
- To investigate the molecular mechanisms of chronic rejection in rat aortic allografts.
- To evaluate the efficacy of lanreotide, a somatostatin analog, in inhibiting myocyte proliferation.
- To identify key mediators involved in allograft arteriosclerosis.
Main Methods:
- Utilized nonimmunosuppressed rat aortic allografts to study chronic rejection.
- Quantified the synthesis of growth-promoting substances in the vascular wall.
- Administered lanreotide (BIM 23014) in vivo and assessed its effect on myocyte proliferation.
- Examined the impact of lanreotide on local peptide growth factor levels in vitro and in vivo.
Main Results:
- Chronic rejection involved increased synthesis of interleukin-1, eicosanoids, and peptide growth factors.
- Lanreotide significantly inhibited myocyte proliferation in allografts in vivo.
- Lanreotide did not inhibit smooth muscle cell proliferation in vitro.
- Administration of lanreotide reduced levels of epidermal growth factor, insulin-like growth factor 1, and PDGF-BB, but not other inflammatory mediators.
Conclusions:
- Peptide growth factors are key effectors driving myocyte proliferation in allograft arteriosclerosis.
- Lanreotide shows potential as a specific therapeutic agent to inhibit allograft arteriosclerosis and chronic rejection.