iRhom2 Promotes Lupus Nephritis through ADAM17-Dependent TNF-α and EGFR Signaling. iRhom2 Promotes Lupus Nephritis through ADAM17-Dependent TNF-α and EGFR Signaling

Lupus nephritis (LN) often results in progressive renal dysfunction. The inactive Rhomboid 2 (iRhom2) is a newly identified key regulator of A disintegrin and metalloprotease 17 (ADAM17), whose substrates, such as TNF-α and heparin-binding EGF (HB-EGF), have been implicated in the pathogenesis of chronic kidney disease. Here we demonstrate that deficiency of iRhom2 protects the lupus-prone Fcgr2b-/- mice from developing severe kidney damage without altering anti-double stranded (ds) DNA Ab production, by simultaneously blocking the HB-EGF/EGFR and the TNF-α signaling in the kidney tissues. Unbiased transcriptome profiling of kidneys and kidney macrophages revealed that TNF-α and HB-EGF/EGFR signaling pathways are highly upregulated in Fcgr2b-/- mice; alterations that were diminished in the absence of iRhom2. Pharmacological blockade of either TNF-α or EGFR signaling protected Fcgr2b-/- mice from severe renal damage. Finally, kidneys from LN patients showed increased iRhom2 and HB-EGF expression, with interstitial HB-EGF expression significantly associated with chronicity indices. Our data suggest that activation of iRhom2/ADAM17-dependent TNF-α and EGFR signaling plays a crucial role in mediating irreversible kidney damage in LN, thereby uncovering a novel target for selective and simultaneous dual inhibition of two major pathological pathways in the effector arm of the disease. Overall design: [1] Analysis of total kidney transcriptomes in Fcgr2b-/- mice, Rhbdf2-/- mice; Rhbdf2 -/- Fcgr2b-/- mice and the wildtype control. [2] Analysis of CD45+F4/80hiCD11b+Ly6G-Ly6C- kidney macrophages transcriptomes in Fcgr2b-/- mice, Rhbdf2-/- mice; Rhbdf2 -/- Fcgr2b-/- mice and the wildtype control.