B cells support the repair of injured tissues by adopting MyD88-dependent regulatory functions and phenotype.

Exogenously applied mature naïve B220+ /CD19+ /IgM+ /IgD+ B cells are strongly protective in the context of tissue injury. However, the mechanisms by which B cells detect tissue injury and aid repair remain elusive. Here, we show in distinct models of skin and brain injury that MyD88-dependent toll-like receptor (TLR) signaling through TLR2/6 and TLR4 is essential for the protective benefit of B cells in vivo, while B cell-specific deletion of MyD88 abrogated this effect. The B cell response to injury was multi-modal with simultaneous production of both regulatory cytokines, such as IL-10, IL-35, and transforming growth factor beta (TGFß), and inflammatory cytokines, such as tumor necrosis factor alpha (TNFα), IL-6, and interferon gamma. Cytometry analysis showed that this response was time and environment-dependent in vivo, with 20%-30% of applied B cells adopting an immune modulatory phenotype with high co-expression of anti- and pro-inflammatory cytokines after 18-48 h at the injury site. B cell treatment reduced the expression of TNFα and increased IL-10 and TGFß in infiltrating immune cells and fibroblasts at the injury site. Proteomic analysis further showed that B cells have a complex time-dependent homeostatic effect on the injured microenvironment, reducing the expression of inflammation-associated proteins, and increasing proteins associated with proliferation, tissue remodeling, and protection from oxidative stress. These findings chart and validate a first mechanistic understanding of the effects of B cells as an immunomodulatory cell therapy in the context of tissue injury.

GapmeR cellular internalization by macropinocytosis induces sequence-specific gene silencing in human primary T-cells.

Post-transcriptional gene silencing holds great promise in discovery research for addressing intricate biological questions and as therapeutics. While various gene silencing approaches, such as siRNA and CRISPR-Cas9 techniques, are available, these cannot be effectively applied to "hard-to-transfect" primary T-lymphocytes. The locked nucleic acid-conjugated chimeric antisense oligonucleotide, called "GapmeR", is an emerging new class of gene silencing molecule. Here, we show that GapmeR internalizes into human primary T-cells through macropinocytosis. Internalized GapmeR molecules can associate with SNX5-positive macropinosomes in T-cells, as detected by super-resolution microscopy. Utilizing the intrinsic self-internalizing capability of GapmeR, we demonstrate significant and specific depletion (>70%) of the expression of 5 different endogenous proteins with varying molecular weights (18 kDa Stathmin, 80 kDa PKCε, 180 kDa CD11a, 220 kDa Talin1 and 450 kDa CG-NAP/AKAP450) in human primary and cultured T-cells. Further functional analysis confirms CG-NAP and Stathmin as regulators of T-cell motility. Thus, in addition to screening, identifying or verifying critical roles of various proteins in T-cell functioning, this study provides novel opportunities to silence individual or multiple genes in a subset of purified human primary T-cells that would be exploited as future therapeutics.