Abstract: TH-PO029

Absence of RORyt+ Foxp3+ biTregs Aggravates Glomerulonephritis

Session Information

Category: Glomerular

  • 1001 Glomerular: Basic/Experimental Immunology and Inflammation

Authors

  • Ramcke, Torben, University Hospital Hamburg Eppendorf, Hamburg, Germany
  • Nosko, Anna, University Hospital Hamburg Eppendorf, Hamburg, Germany
  • Stahl, Rolf A., University Hospital Hamburg Eppendorf, Hamburg, Germany
  • Kluger, Malte A., University Hospital Hamburg Eppendorf, Hamburg, Germany
  • Steinmetz, Oliver M., University Hospital Hamburg Eppendorf, Hamburg, Germany
Background

Recently, cells expressing the unusual combination of the Treg transcription factor Foxp3, together with the Th17 charateristic RORyt were identified (biTregs). In models of glomerulonephritis, we found protection by transfer of exogenous biTregs. However, selective deletion of RORyt in biTregs revealed additional pro-inflammatory effects, including IL-17 secretion and suppression of Th2 immunity. The net effect of complete absence of RORyt+ biTregs, as opposed to sole knockout of RORyt in Tregs, remains unknown to date.

Methods

CD4+ T cells, containing or lacking biTregs, were sorted from RORyt Foxp3 double reporters and transferred into RAG1-/- recipients. Development of transfer colitis and nephrotoxic nephritis (NTN) were assessed at varying time points after cell transfer. Immune responses and renal outcome parameters were studied. Finally, immunosuppressive mechanisms of biTregs were analysed by adoptive transfer and in vitro assays.

Results

BiTregs were readily detectable at all time points after transfer. In contrast, they failed to develop de-novo in mice receiving biTreg depleted T cells. Furthermore, the Treg/Th17 balance was not disturbed, underlining their independent character. Selective absence of biTregs did not cause generalized lymphoproliferation or accelerated transfer colitis. Importantly, however, nephritis was aggravated in mice lacking biTregs with enhanced renal inflammatory mRNA expression, leukocyte infiltration and tissue damage. Interestingly, while selective ablation of RORyt in Tregs resulted in enhanced Th2 immunity, complete absence of biTregs did not. Transfer of exogenous biTregs into immunocompetent mice revealed broad immunosuppressive capacity with no preference for Th2 responses.

Conclusion

We developed a new model, which mimicks knockout of biTregs. Absence of biTregs did not accelerate transfer colitis but significantly aggravated glomerulonephritis. In contrast to isolated deletion of RORyt in Tregs, complete lack of biTregs did not result in selectively enhanced Th2 responses. In summary, we provide further evidence that biTregs are novel and independent regulators of inflammation with broad immunosuppressive capacity.

Funding

  • Government Support - Non-U.S.