Hepatic granulomas induced by Schistosoma mansoni in mice deficient for connexin 43 present lower cell proliferation and higher collagen content Silvia Catarina Salgado Oloris a , Marc Mesnil b , Viviane Neri de Souza Reis a , Mônica Sakai c , Patrícia Matsuzaki a , Evelise de Souza Monteiro Fonseca c , Tereza Cristina da Silva a , José Luís Avanzo a , Idércio Luiz Sinhorini a , José Luiz Guerra a , Frederico Azevedo Costa-Pinto a , Paulo Cesar Maiorka a , Maria Lúcia Zaidan Dagli a, ⁎ a Laboratory of Experimental Oncology, Department of Pathology, School of Veterinary Medicine, University of São Paulo, Brazil b Institute of Cellular Physiology and Biology, CNRS-UMR 6187, University of Poitiers, France c Laboratory of Applied Pharmacology, Department of Pathology, School of Veterinary Medicine, University of São Paulo, Brazil Received 26 June 2006; accepted 15 December 2006 Abstract Granuloma formation involves a coordinated interaction between monocytes and macrophages, epithelioid cells, lymphocytes, eosinophils, neutrophils and fibroblasts. It has been established that extracellular communication via cytokines is important for the assembly of granulomas. However, the importance of gap junctions and intercellular communication to granuloma formation and development had never been assessed. Connexins are proteins that form gap junctions, and connexin 43 (Cx43) is present in macrophages, lymphoid cells, myelogenous cells, fibroblasts and others. We analyzed the effect of heterologous deletion of Gja1 (Cx43 gene) on the formation and development of hepatic granulomas induced by Schistosoma mansoni eggs. Heterozygous (Cx43 +/- ) and wild-type (Cx43 +/+ ) mice were infected subcutaneously with S. mansoni cercarie and evaluated after 6, 8 and 12 weeks. Granuloma cells express Cx43, as revealed by real-time PCR in isolated granulomas, and by immunohistochemistry. Cx43 expression was reduced in Cx43 +/- mice, as expected. No differences in the average area of granulomas or number of cells per granuloma were observed between mice of different genotypes. However, granuloma cells from Cx43 +/- mice displayed a reduced index of the proliferating cell nuclear antigen (PCNA) labeling at 8 and 12 weeks post-infection. Moreover, Cx43 +/- granulomas unexpectedly presented a higher degree of fibrosis, quantified by morphometric analysis in Sirius Red-stained slides. Our results indicate that the deletion of one allele of the Cx43 gene, and possibly the reduced gap junction intercellular communication capacity (GJIC), may impair the interactions between granuloma cells, reducing their proliferation and increasing their collagen content, thereby modifying the characteristics of S. mansoni granuloma in mice. © 2007 Elsevier Inc. All rights reserved. Keywords: Gap junction; Connexin; Granuloma; Schistosoma mansoni; Fibrosis; Cell proliferation Introduction Granulomas are lesions that occur during chronic inflam- mation in response to various stimuli, leading to the isolation of harmful substances from the surrounding healthy tissues (Jinnouchi et al., 2003). The major histological feature of a granuloma is the nodular accumulation of macrophages, epithelioid cells and multinucleate giant cells. Additionally, lymphocytes, plasma cells and polymorphonuclear leukocytes may be present (Jinnouchi et al., 2003). The formation of granulomatous lesions is a complex dynamic process that leads to the inflammatory destruction or confinement of the inciting agent. This process involves recruitment of blood monocytes to the inflammatory sites, followed by coordinated interactions among lymphocytes, monocytes and macro- phages, epithelioid cells, eosinophils, neutrophils and fibro- blasts (Takahashi et al., 1999). It is known that extracellular communication, mediated by cytokines, is important to Life Sciences 80 (2007) 1228 – 1235 www.elsevier.com/locate/lifescie ⁎ Corresponding author. Faculdade de Medicina Veterinária e Zootecnia, Departamento de Patologia, Av. Prof. Dr. Orlando Marques de Paiva, 87, Universidade de São Paulo, São Paulo, SP, CEP 05508-900, Brazil. Tel.: +55 11 3091 7712; fax: +55 11 3091 78 29. E-mail address: mlzdagli@usp.br (M.L.Z. Dagli). 0024-3205/$ - see front matter © 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.lfs.2006.12.030