Abstract: TH-PO056

Neutrophil-Gelatinase Associated Lipocalin (NGAL) Attenuates ANCA-Induced Glomerulonephritis by Inhibiting Th17 Immunity

Session Information

Category: Glomerular

  • 1001 Glomerular: Basic/Experimental Immunology and Inflammation

Authors

  • Schreiber, Adrian, Charite Berlin, Berlin, Germany
  • Panzer, Ulf, None, Hamburg, Germany
  • Rousselle, Anthony, ECRC, Berlin, Germany
  • Kettritz, Ralph, Universitatsmedizin Berlin, Berlin, Germany
Background

ANCA activate neutrophils and monocytes and thereby participate in vasculitis and necrotizing crescentic glomerulonephritis (NCGN). NGAL is a marker of intrinsic kidney injury and is expressed by neutrophils and renal tubular cells. Whether or not NGAL is merely a diagnostic marker or participates mechanistically in renal damage is not known. We hypothesized that neutrophil NGAL plays a pathogenic role in ANCA-induced NCGN.

Results

Patients with active ANCA disease demonstrated strongly increased NGAL serum levels by western blot analysis (47.3±13.1 optical density, OD) compared to patients in remission (19.4±8.1OD) and healthy controls (2.1±0.4OD). By ELISA, both PR3-ANCA and MPO-ANCA stimulated NGAL release from human neutrophils (887±72 and 961±70 ng/ml, respectively), whereas control IgG induced much lower levels (105±21ng/ml). In addition, mice with anti-MPO-induced NCGN demonstrated upregulated NGAL serum levels. To assess the role of neutrophil NGAL in vivo, we used a murine model of anti-MPO induced NCGN, where mMPO-immunized MPO-deficient mice were transplanted with either WT- or NGAL-deficient BM. NCGN was significantly aggravated in mice that received NGAL-deficient BM (34.8±6.1% crescents in NGAL-KO versus 13.4±2.8% in WT mice). With respect to intrinsic neutrophil function, migration, ROS generation, degranulation and apoptosis were similar in NGAL-KO and WT neutrophils. In addition, humoral immunity to MPO did not differ between both groups. In contrast, flow cytometry demonstrated significantly increased renal T-cells in NGAL-deficient mice: TH17 cells were 21.7±7.6% of renal CD4 cells versus 5.7±1.0%. Splenocytes from NGAL-deficient mice demonstrated a higher proliferation rate than splenocytes from WT mice. Finally, to assess the specific role of TH17 immunity in anti-MPO-induced NCGN, immunized MPO-KO and MPO-/IL17A-double-KO mice were transplanted with either WT or IL17A-KO BM, respectively. NCGN was significantly attenuated in IL17A-KO mice compared to WT mice as assessed by urine pathology and renal histology (2.5±1.3% crescents in MPO-/IL17A-double-KO versus 29.6±7.2% in MPO-KO mice).

Conclusion

Our findings indicate that neutrophil NGAL down-regulates inflammation in ANCA-induced NCGN by inhibiting TH17 immunity and TH17 cells are clearly necessary for induction of ANCA-mediated NCGN.

Funding

  • Government Support - Non-U.S.