Role of MAP kinase pathways in mediating IL-6 production in human primary mesangial and proximal tubular cells

Martin Leonard, Michael P. Ryan*, Alan J. Watson, Herbert Schramek, Edel Healy

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

104 Citations (Scopus)

Abstract

Background. Both interleukin-6 (IL-6) and tumor necrosis factor-α (TNF- α) are pleiotropic cytokines that have been implicated in the development of glomerular and tubular injury in various forms of immune-mediated renal disease, including glomerulonephritis. Although TNF-α has been shown to stimulate IL-6 production in renal cells in culture, the signaling mechanisms that regulate IL-6 production are not fully understood. The aim of this study was to examine the role of the p38 and extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase (MAPK) pathways in regulating TNF-α- mediated IL-6 production from both primary human mesangial cells (HMCs) and human proximal tubular (HPT) cells. Methods. Primary mesangial and proximal tubular cells were prepared from nephrectomized human kidney tissue. Cells were treated for 24 hours with TNF-α in the presence and absence of the specific p38 and ERK1,2 MAPK inhibitors SB203580 and PD98059, respectively, either alone or in combination. IL-6 levels in the cell culture media were measured by enzyme-linked immunosorbent assay. MAPK activation was demonstrated by immunoblot for the active kinase (tyrosine/threonine phosphorylated) in whole cell extracts using phospho-specific antibodies, p38 MAPK activity in HPT cells was measured using an in vitro immunokinase assay using ATF2 as the substrate. Results. TNF-α (0.1 to 100 ng/ml) stimulated a dose-dependent increase in IL-6 production in both renal cell types. The activation of the p38 and the ERK1,2 MAPKs occurred following TNF-α stimulation. The role of these activations in IL-6 production was confirmed by the ability of both inhibitors SB203580 (1 to 30 μM) and PD98059 (0.01 to 10 μM) to inhibit basal and TNF-α-stimulated IL-6 production in both cell types. The addition of both inhibitors in combination caused greater decreases in IL-6 production compared with either inhibitor alone. Pretreatment with SB203580 (10 μM) had no effect on basal or TNF-α- stimulated phosphorylation of p38 MAPK but completely abolished TNF, α- stimulated p38 MAPK activity. PD98059 decreased both basal and TNF-α- stimulated phosphorylation of ERK1,2. Conclusions. This study provides evidence that both the p38 and ERK MAPK pathways are important for the regulation of the production of IL-6 from the proximal tubular and glomerular mesangial regions of the nephron. In response to TNF-α, the activation of both pathways leads to IL-6 production. These findings could aid in an understanding of the cellular mechanisms that regulate IL-6 production and could provide insights into possible pharmacological strategies in inflammatory renal disease.

Original languageEnglish
Pages (from-to)1366-1377
Number of pages12
JournalKidney International
Volume56
Issue number4
DOIs
Publication statusPublished - 1999

Bibliographical note

Funding Information:
This work was supported by the Health Research Board of Ireland, Enterprise Ireland (The Irish Science and Technology Agency), European Commission Biotechnology Programme (contract no. B104-97-2006), and by the Irish Kidney Association. We acknowledge Dr. Zarin Brown for her advice on the isolation of HMCs and the secretarial assistance of Ms. Colette O'Beirne. The help of the urology teams from Dublin hospitals in the provision of human renal tissue is also gratefully acknowledged. Part of this work was presented at the 1997 and 1998 annual meetings of the American Society of Nephrology and was published in abstract form (J Am Soc Nephrol 8:442A, 1997, and J Am Soc Nephrol 9:426A, 1998).

Keywords

  • Cytokines
  • Glomerulonephritis
  • Inflammatory renal disease
  • Interleukin-6
  • MAPK
  • TNF- α

Fingerprint

Dive into the research topics of 'Role of MAP kinase pathways in mediating IL-6 production in human primary mesangial and proximal tubular cells'. Together they form a unique fingerprint.

Cite this