Identification and Characterization of a Novel Nanobody Against Human CTGF to Reveal Its Antifibrotic Effect in an in vitro Model of Liver Fibrosis

Background: No agents are currently available for the treatment or reversal of liver fibrosis. Novel antifibrotic therapies for chronic liver diseases are thus urgently needed. Connective tissue growth factor (CTGF) has been shown to contributes profoundly to liver fibrogenesis, which makes CTGF as a promising target for developing antifibrotic agents. Methods: In this study, we identified a novel nanobody (Nb) against human CTGF (anti-CTGF Nb) by phage display using an immunized camel, which showed high affinity and specificity in vitro. LX-2 cells, the immortalized human hepatic stellate cells, were induced by transforming growth factor beta1 (TGF & beta;1) as an in vitro model of liver fibrosis to verify the antifibrotic activity of the anti-CTGF Nb. Results: Our data demonstrated that anti-CTGF Nb effectively alleviated TGF & beta;1-induced LX-2 cell proliferation, activation, and migration, and promoted the apoptosis of activated LX-2 cells in response to TGF & beta;1. Moreover, the anti-CTGF Nb remarkably reduced the levels of TGF & beta;1, Smad2, and Smad3 expression in LX-2 stellate cells stimulated by TGF & beta;1. Conclusion: Taken together, we successfully identified a novel Nb against human CTGF, which exhibited antifibrotic effects in vitro by regulating the biological functions of human stellate cells LX-2.