Local expression of apolipoprotein A-I gene and a possible role for HDL in primary defence in the carp skin》.pdfVIP

Fish Shellfish Immunology (2003) 14, 259–273 doi:10.1006/fsim.2002.0435 Available online at on Local expression of apolipoprotein A-I gene and a possible role for HDL in primary defence in the carp skin MARGARITA I. CONCHA*, SOFIuA MOLINA, CARLOS OYARZUuN, JULIETA VILLANUEVA AND RODOLFO AMTHAUER Instituto de Bioquímica, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile (Received 8 February 2002, accepted 25 April 2002) Antimicrobial proteins and peptides play an important role in the primary defence of epithelial barriers in vertebrates and invertebrates. Here we report the detection of the apolipoproteins A-I and A-II in the epidermis and epidermal mucus of the carp (Cyprinus carpio L.) by immunohistochemistry and Western blot analysis. Both apolipoproteins are major constituents of high density lipoprotein and have been shown to display antiviral and antimicrobial activity in mammals. Therefore the aim of this study was to evaluate if they could be part of the innate immune system of teleost fish. A cDNA clone containing most of the coding region for carp apoA-I was isolated and used as a probe to demonstrate the expression of apoA-I gene in the skin. In addition, mucus apoA-I was shown to be associated to small particles that could correspond to nascent HDL. Finally, a$nity purified plasma HDL displayed bactericidal activity in vitro against a non-pathogenic Escherichia coli strain, suggesting a defensive role for HDL and its associated proteins in the carp epidermis and mucus. 2002 Elsevier Science Ltd. All rights reserved. Key words: apolipoprotein A-I, HDL, antimicrobial protein, mucus, teleost fish, epidermis.