Nanoparticle-mediated peptide delivery to liver sinusoidal endothelial cells protects from CD8 T cell-driven cholangitis

Question:

We have previously shown that delivery of MHC II-restricted autoantigen peptides to liver sinusoidal endothelial cells (LSECs) using LSEC-targeting nanoparticles (NPs) provides effective protection from CD4 T cell-driven autoimmunity (Carambia et al. J Hepatol 2015). As LSECs are capable to cross-present exogenous peptides to CD8 T cells, we here investigated whether targeted delivery of MHC I-restricted autoantigen peptide to LSECs might serve antigen-specific treatment of CD8 T cell-driven autoimmunity. As a model, we used OT-I T cell-driven cholangitis in K14-OVAp mice expressing the cognate SIINFEKL peptide as autoantigen in cholangiocytes (Schwinge et al. J Immunol. 2015).

Methods:

LSEC-targeting NPs loaded with SIINFEKL peptide (SIINFEKL-NPs) or control NPs without peptide cargo were administered to K14-OVAp mice one day before transfer of pathogenic OT-I T cells. Five days after OT-I T cell transfer, clinical parameters of liver pathology were assessed and immunophenotyping of hepatic infiltrates, in particular of the transferred autoreactive CD8 T cells, was performed.

Results:

Adoptive transfer of OT-I CD8 T cells to K14-OVAp recipients induced liver inflammation and injury in control mice receiving unloaded NPs, while K14-OVAp mice receiving SIINFEKL-NP were largely protected from any signs of liver damage. Accordingly, upon SIINFEKL-NP treatment, serum transaminases were not elevated, and body condition remained unaffected, as compared to control animals, which showed elevated serum transaminase levels (ALT 33 vs. 140 U/mL; P = 0.0317; AST 159 vs. 617 U/mL) and poor body condition, including significant weight loss (weight change +0.86% vs. -8.95%; P = 0.0149). Moreover, the protective effect of SIINFEKL-NP treatment was associated with significantly reduced liver-infiltration of pathogenic OT-I T cells (42.2% vs. 77.3% of CD8; P = 0.0159). Furthermore, upon SIINFEKL-NP treatment, OT-I cells retrieved from the livers of K14-OVAp mice manifested a tolerized phenotype with significant up-regulation of PD-1 (MFI 8708 vs. 5600, P = 0.0079) and down-regulation of IFN gamma (76.8% vs. 49.8%, P = 0.0012) and granzyme B (71.9% vs. 28.4%, P = 0.0079).

Conclusions:

Our study provides proof-of-concept that LSEC-targeting NPs could function as antigen-specific therapeutic platform providing treatment for CD8 T cell-driven autoimmune responses, in addition to CD4 T cell-driven autoimmune diseases, as previously shown.