Abstract
One of the pathways activated during liver fibrosis is the Rho kinase pathway, which regulates activation, migration, and contraction of hepatic stellate cells (HSC). Inhibition of this kinase by the Rho kinase inhibitor Y27632 [(+)-(R)-trans- 4-(1-aminoethyl)-N-(4-pyridyl)cyclohexanecarboxamide dihydrochloride] has been shown to reduce fibrosis in animal models. However, kinase expression is ubiquitous, so any inhibitor may affect many cell types. We hypothesize that cell-specific delivery of a kinase inhibitor will be beneficial. Therefore, we conjugated Y27632 to the carrier mannose-6-phosphate (M6P) human serum albumin (HSA), which is taken up specifically in activated HSC through the M6P/insulin-like growth factor II receptor. This conjugate decreased protein expression of phosphorylated myosin light chain 2 (pMLC2) and vinculin, downstream of Rho kinase, in activated primary HSC and decreased the migration and contraction of HSC. In an ex vivo model, free Y27632 decreased contractility of rat aortas, whereas the Y27-conjugate did not, showing that the Y27-conjugate does not affect nontarget tissue. In chronic CCl4-induced liver fibrosis, both free drug and conjugate reduced HSC activation; however, only the Y27-conjugate significantly reduced collagen deposition. Treatment with the Y27-conjugate, but not with free drug, reduced pMLC2 expression in livers 24 h after injection, demonstrating prolonged inhibition of the Rho kinase pathway. The Rho kinase inhibitor Y27632 can be specifically targeted to HSC using M6PHSA, decreasing its effects in nontarget tissues. The targeted drug effectively reduced fibrotic parameters in vivo via the inhibition of the Rho kinase pathway.
Footnotes
This work was supported by the European Framework Program FP6 [Grant LSHB-CT-2007-036644].
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
doi:10.1124/jpet.111.179143.
↵ The online version of this article (available at http://jpet.aspetjournals.org) contains supplemental material.
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ABBREVIATIONS:
- HSC
- hepatic stellate cells
- TGF-β
- transforming growth factor β
- PDGF
- platelet-derived growth factor
- M6P
- mannose-6-phosphate
- HSA
- human serum albumin
- IGFII
- insulin-like growth factor II
- ULS
- Universal Linkage System
- α-SMA
- α-smooth muscle actin
- MLC
- myosin light chain
- pMLC
- phosphorylated MLC
- Y27632
- (+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl)cyclohexanecarboxamide dihydrochloride
- PBS
- phosphate-buffered saline: HPLC, high-performance liquid chromatography.
- Received January 10, 2011.
- Accepted March 3, 2011.
- Copyright © 2011 by The American Society for Pharmacology and Experimental Therapeutics
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