Kidney Week

Abstract: FR-PO612

Activation of Toll-Like Receptor 2 Stimulated NF-κB-Mediated Inflammatory Responses and ERK-Mediated Cell Proliferation in ADPKD

Session Information

• Cystic Kidney Diseases: Mechanisms and Models
  October 25, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Genetic Diseases of the Kidneys

• 1201 Genetic Diseases of the Kidneys: Cystic

Authors

• Zhang, Yang, Michigan Technological University, Houghton, Michigan, United States

Yang Zhang, APN, APRN

• Plansinis, Matthew V., Michigan Technological University, Houghton, Michigan, United States

Matthew V. Plansinis

• Peake, Sophia Y., Michigan Technological University, Houghton, Michigan, United States

Sophia Y. Peake

• Weber, Elisabeth Grace, Michigan Technological University, Houghton, Michigan, United States

Elisabeth Grace Weber

• Reif, Gail, The University of Kansas Medical Center, Kansas City, Kansas, United States

Gail Reif

• Wallace, Darren P., The University of Kansas Medical Center, Kansas City, Kansas, United States

Darren P. Wallace, PhD

• Zhang, Yan, Michigan Technological University, Houghton, Michigan, United States

Yan Zhang, PhD

Background

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by progressive formation of numerous fluid-filled cysts. Aberrant innate immune responses play pivotal roles in driving cyst growth and disease progression; however, the precise molecular mechanisms remain poorly understood. Toll-like receptors (TLRs) are the key components of the innate immunity. Upon ligand binding, TLRs recruit MyD88, an adaptor protein, leading to the activation of transforming growth factor-β-activated kinase 1 (TAK1). TAK1 in turn activates ERK and NF-κB, key factors regulating disease progression in ADPKD. Currently, the effect of TLR activation has not been studied in ADPKD.

Methods

We measured the expression levels of TLR2, TLR4, MyD88, IκBα, and NF-κB p65 in human ADPKD kidneys and normal human kidneys (NHK) by qPCR) and immunoblot. NF-κB p65 nuclear localization was assessed using immunohistochemistry (IHC). To determine the effects of TLR2 and TLR4 activation, cultured ADPKD and NHK cells were treated with Pam3CSK4, a synthetic TLR2 agonist, or ultra-pure LPS-EK, a specific TLR4 agonist, and NF-κB signaling pathways, phosphorylated ERK (P-ERK), and cell proliferation were assessed.

Results

mRNA levels of TLR2, TLR4, MyD88, and NF-κB were significantly elevated in human ADPKD kidneys compared to NHK. IHC analysis revealed increased nuclear localization of NF-κB p65 in human ADPKD kidneys, along with reduced IκBα protein, demonstrating that the TLRs/NF-κB is upregulated in human ADPKD kidneys. Cellular experiment showed that treatment with Pam3CSK4 for increased the phosphorylation of IκBα (P-IκBα) and decreased total IκBα in ADPKD cells. Pam3CSK4 remarkably increased nuclear levels of NF-κB p65 and consequently increased the mRNA of IL-1β, TNF-α, and MCP-1, key factors creating a pro-inflammatory microenvironment in ADPKD kidneys. Moreover, we found that Pam3CSK4 increased P-ERK/ERK and cell proliferation in ADPKD cells but not in NHK cells. LPS-EK had limited effects on NF-κB and ERK in ADPKD and NHK cells.

Conclusion

Activation of TLR2 stimulated NF-κB-mediated expression of inflammatory cytokine and chemokines and ERK-mediated proliferation in ADPKD cells, providing insight into the molecular mechanisms by which innate immunity promotes disease progression.

Funding

• NIDDK Support