iRhom2 promotes lupus nephritis through 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-alpha and heparin-binding EGF (HB-EGF), have been implicated in the pathogenesis of chronic kidney diseases. Here, we demonstrate that deficiency of iRhom2 protects the lupus-prone Fcgr2b(-/-) mice from developing severe kidney damage without altering anti-double stranded DNA (anti-dsDNA) Ab production by simultaneously blocking HB-EGF/EGFR and INF-alpha signaling in the kidney tissues. Unbiased transcriptome profiling of kidneys and kidney macrophages revealed that TNF-alpha and HB-EGF/EGFR signaling pathways are highly upregulated in Fcgab(-/-) mice, alterations that were diminished in the absence of iRhom2. Pharmacological blockade of either TNF-alpha or EGFR signaling protected Frgr2(b-/-) 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-alpha and EGFR signaling plays a crucial role in mediating irreversible kidney damage in LN, thereby uncovering a target for selective and simultaneous dual inhibition of 2 major pathological pathways in the effector arm of the disease.