ABSTRACT
Camelid single-domain antibody fragments (nanobodies) are an emerging force in therapeutic biopharmaceuticals and clinical diagnostic reagents in recent years. Nearly all nanobodies available to date have been obtained by animal immunization, a bottleneck restricting the large-scale application of nanobodies. In this study, we developed three kinds of gene designated-region pan-editing (GDP) technologies to introduce multiple mutations in complementarity-determining regions (CDRs) of nanobodies in vitro. Including the integration of G-quadruplex fragments in CDRs, which induces the spontaneous multiple mutations in CDRs; however, these mutant sequences are highly similar, resulting in a lack of sequences diversity in the CDRs. We also used CDR-targeting traditional gRNA-guided base-editors, which effectively diversify the CDRs. And most importantly, we developed the self-assembling gRNAs, which are generated by reprogrammed tracrRNA hijacking of endogenous mRNAs as crRNAs. Using base-editors guided by self-assembling gRNAs, we can realize the iteratively diversify the CDRs. And we believe the last GDP technology is highly promising in immunization-free nanobody library construction, and the full development of this novel nanobody discovery platform can realize the synthetic evolution of nanobodies in vitro.
ABSTRACT
Preliminary results and emerging data have shown that lipid droplet high (LDhi ) immunosuppressive cells accumulate in tumour tissues. By tracking and phenotypic profiling of LDhi cells, we find that LDhi CD19+ , LDhi CD11b+ , and LDhi Ly6G+ immune cell populations appear in the spleen, thymus, and tumour tissues in a syngeneic tumour model. Using a contact-dependent reporter system, we discover a LDhi CCR7hi immunosuppressive cell population that migrates from tumour tissues to the spleen and thymus. Hence, we engineered a family of chimeric antigen receptor-modified macrophages (CAR-Ms) that direct macrophages to CCR7-positive cells and show that the cytosolic domain from Mer receptor tyrosine kinase (MerTK) triggers tumour cell cytotoxicity by the CAR-Ms. In vivo, CCR7-targeted CAR-Ms suppressed tumour growth and prolonged survival by preventing metastasis and by inducing systemic anti-tumour immunity through retarding the migration of LDhi CCR7hi immunosuppressive cells from tumour tissues to distal immune organs, indicating an important role for CCR7 in tumour cell-induced immune tolerance. © 2020 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
