Effects of Type 2 Cytokines on Glomerular Epithelial Cells

Visceral glomerular epithelial cells (GECs) are involved in the maintenance of the filtration barrier and may play a role in immune responses. Cytokines may act on GECs and we wished to test this in vitro. Vascular endothelial growth factor (VEGF) is a specific product of the GEC that may play a role in glomerular permeability. We have investigated whether GECs in culture express receptors for interleukin (IL)-4, 10 and 13 (often grouped together as type 2 cytokines) and whether these cytokines alter GEC VEGF production. Type 2 cytokines were compared to transforming growth factor-β (TGF-β) and IL-1β which are known to upregulate VEGF production. GECs were grown from human nephrectomy specimens and cultured with and without the addition of exogenous cytokines. Messenger RNA data demonstrated the presence of IL-4 receptor α, IL-10 receptor 1 and 2, and IL-13 receptors α 1 and α 2 . However, at the protein level by flow cytometry, only IL-13 α 2 could be consistently demonstrated. IL-4, IL-10 and IL-13 inhibited production of VEGF but did not affect the pattern of isoform expression. In contrast, TBF-β and IL-1β caused an increase in VEGF production. These effects were not explained by effects on proliferation. Our data provide evidence that GECs express receptors for type 2 cytokines and that these cytokines can act directly on GECs, to decrease VEGF production.