In a murine model of lupus, TLR9 suppresses the production of TLR7-dependent RNA-associated autoantibodies, demonstrating that TLR9 regulates and TLR7 enhances disease manifestation.
In a murine lupus model, TLR9 suppresses TLR7-dependent autoantibody production, revealing cross-regulation between TLR pathways in autoimmune disease.
Abstract Systemic lupus erythematosus is characterized by the production of autoantibodies against nucleic acid-associated Ags. We previously found that Tlr7 was required for anti-Sm and Tlr9 for anti-chromatin autoantibodies. Yet, although Tlr7 deficiency ameliorated disease, Tlr9 deficiency exacerbated it. Despite the mechanistic and clinical implications of this finding, it has yet to be elucidated. In this study, we characterize MRL/lpr lupus-prone mice genetically deficient in Tlr7, Tlr9, both Tlr7 and Tlr9, or Myd88 to test whether Tlr7 and Tlr9 function independently or instead regulate each other. We find that disease that is regulated by Tlr9 (and hence is worse in its absence) depends on Tlr7 for its manifestation. In addition, although Tlr7 and Tlr9 act in parallel pathways on different subsets of autoantibodies, Tlr9 also suppresses the production of Tlr7-dependent RNA-associated autoantibodies, suggesting previously unrecognized cross-regulation of autoantibody production as well. By comparing disease in mice deficient for Tlr7 and/or Tlr9 to those lacking Myd88, we also identify aspects of disease that have Tlr- and Myd88-independent components. These results suggest new models for how Tlr9 regulates and Tlr7 enhances disease and provide insight into aspects of autoimmune disease that are, and are not, influenced by TLR signals.
Nickerson et al. (Wed,) conducted a other in Systemic lupus erythematosus. Genetic deficiency in Tlr7, Tlr9, both, or Myd88 vs. Mice with different genetic deficiencies was evaluated on Autoantibody production and disease manifestation. In a murine model of lupus, TLR9 suppresses the production of TLR7-dependent RNA-associated autoantibodies, demonstrating that TLR9 regulates and TLR7 enhances disease manifestation.