Cytokine mRNA expression by cultured rat mesangial cells after contact with environmental lectins

We previously demonstrated that gliadin, a lectinic component of gluten, induces IgA mesangial deposits in orally immunized mice, binds in vitro polymeric IgA and cultured rat mesangial cells modulating their arachidonic acid metabolism. We investigated the effects of gliadin and other environmental lectins on some mesangial cell functions, including synthesis and release of cytokines and lipid mediators. Several lectins, particularly gliadin, affected the mRNA expression of c-myc and c-fos, two proto-oncogenes involved in the transcriptional enhancement of the gene cascade, which are markers of cell growth, differentiation and mitosis. Lectins modulated the ability of cultured rat mesangial cells to express mRNA for cytokines involved in the inflammation and in the regulation of the immune response. TNF-alpha and IL-6 mRNA transcription were enhanced by gliadin and other lectins, and TNF release was variably increased. Conversely, IL-1 production was less affected or slightly depressed. PAF production was not detectable while PGE2 was generally reduced and TXB2 enhanced. Gliadin was one of the lectins most active on the mesangial cells, and its effects were reversed by the addition of N-Acetylglucosamine, a sugar specific for some lectinic bindings, suggesting a carbohydrate interaction. The effects of the various lectins were distinct and only partially convergent, ruling out an aspecific mesangial cell activation. These data suggest that lectins might interfere with mesangial cell functions and modify the mesangial cell homeostasis.