Interplay of cysteinyl leukotrienes and TGF-β in the activation of hepatic stellate cells from Schistosoma mansoni granulomas

• Published in: Biochimica et biophysica acta 2010-12, Vol.1801 (12), p.1341-1348
• Main Authors: Paiva, Ligia A., Maya-Monteiro, Clarissa M., Bandeira-Melo, Christianne, Silva, Patricia M.R., El-Cheikh, Marcia C., Teodoro, Anderson J., Borojevic, Radovan, Perez, Sandra A.C., Bozza, Patricia T.
• Format: Article
• Language: English
• Subjects: Animals; Arachidonate 5-Lipoxygenase - metabolism; Base Sequence; Blotting, Western; DNA Primers; Granuloma - parasitology; Hepatic Stellate Cells; Inflammation; Leukotrienes; Leukotrienes - biosynthesis; Leukotrienes - metabolism; Lipid droplets; Liver - parasitology; Liver - pathology; Mice; Microscopy, Fluorescence; Reverse Transcriptase Polymerase Chain Reaction; S. mansoni; Schistosoma mansoni - isolation & purification; Schistosoma mansoni - metabolism; Transforming Growth Factor beta - metabolism
• ISSN: 1388-1981; 0006-3002; 1879-2618
• DOI: 10.1016/j.bbalip.2010.08.014

Hepatic stellate cells (HSCs) have a critical role in liver physiology, and in the pathogenesis of liver inflammation and fibrosis. Here, we investigated the interplay between leukotrienes (LT) and TGF-β in the activation mechanisms of HSCs from schistosomal granulomas (GR-HSCs). First, we demonstrated that GR-HSCs express 5-lipoxygenase (5-LO), as detected by immunolocalization in whole cells and confirmed in cell lysates through western blotting and by mRNA expression through RT-PCR. Moreover, mRNA expression of 5-LO activating protein (FLAP) and LTC 4-synthase was also documented, indicating that GR-HSCs have the molecular machinery required for LT synthesis. Morphological analysis of osmium and Oil-Red O-stained HSC revealed large numbers of small lipid droplets (also known as lipid bodies). We observed co-localization of lipid droplet protein marker (ADRP) and 5-LO by immunofluorescence microscopy. We demonstrated that GR-HSCs were able to spontaneously release cysteinyl-LTs (CysLTs), but not LTB 4, into culture supernatants. CysLT production was highly enhanced after TGF-β-stimulation. Moreover, the 5-LO inhibitor zileuton and 5-LO gene deletion were able to inhibit the TGF-β-stimulated proliferation of GR-HSCs, suggesting a role for LTs in HSC activation. Here, we extend the immunoregulatory function of HSC by demonstrating that HSC from liver granulomas of schistosome-infected mouse are able to release Cys-LTs in a TGF-β-regulated manner, potentially impacting pathogenesis and liver fibrosis in schistosomiasis. ►Hepatic stellate cells obtained from experimentally induced schistosomal granulomas (GR-HSCs) in mice express the enzymes required for leukotrienes synthesis including 5-LO, FLAP and LTC 4-synthase. ►5-LO co-localizes with cytoplasmic lipid droplets in GR-HSCs, suggesting an involvement of lipid droplets in inflammatory mediator production during schistosomiasis. ►Granuloma derived HSCs were shown to spontaneously release low levels of cysteinyl-leukotrienes, which can be enhanced by TGF-β-stimulation. ►Endogenously produced cysLT schistosomiasis pathogenesis was suggested since 5-LO inhibitor zileuton and 5-LO gene deletion was able to inhibit TGF-β-stimulated proliferation of HSCs.