Abstract
Toll-like receptor 7 (TLR7) is an endosomal sensor that responds to both pathogen-derived and self-derived single-stranded RNA (ssRNA). Responses of TLR7 to self-derived ssRNA have been implicated in the development of autoimmune diseases, such as systemic lupus erythematosus (SLE). TLR7 antagonists and inhibitory anti-TLR7 monoclonal antibodies (mAbs) can protect lupus-prone NZBWF1 mice from lethal nephritis. However, less is known about TLR7 dependence and activation in human SLE, as both TLR7 and TLR8 respond to ssRNA in humans. Here, we analyzed public databases and found that TLR7 gene signature scores were consistently elevated across datasets, races, and SLEDAI scores compared to TLR8, suggesting a deeper involvement of TLR7 in SLE pathogenesis. To specifically inhibit human TLR7 responses, we developed inhibitory mAbs against human TLR7. Utilizing an inhibitory clone, we generated the humanized mAb, DS-7011a. DS-7011a effectively inhibited TLR7-mediated responses in plasmacytoid dendritic cells (pDCs) and B cells. Furthermore, DS-7011a was internalized in a TLR7-dependent manner and accumulated in B cells, pDCs, conventional dendritic cells (cDCs), and monocytes/macrophages. In this study, we describe the generation and preclinical development of DS-7011a, which has the potential to be a therapeutic option for the treatment of SLE.