CXCR4 blocking peptide

As cell function is influenced by niche-specific factors in the cellular microenvironment, methods to dissect cell localization and migration can provide further insight on cell function. B-1 a cells are a unique B cell subset in mice that produce protective natural IgM antibodies against oxidation-specific epitopes that arise during health and disease. B-1 a cell IgM production differs depending on B-1 a cell location, and therefore it becomes useful from a therapeutic standpoint to target B-1 a localization to niches supportive of high antibody production. Here we describe a method to target B-la cell migration to the bone marrow by retroviral-mediated overexpression of the C-X-C motif chemokine receptor 4 (CXCR4). Gene induction in primary murine B cells can be challenging and typically yields low transfection efficiencies of 10-20% depending on technique. Here we demonstrate that retroviral transduction of primary murine B-1 a cells results in 30-40% transduction efficiency. This method utilizes adoptive cell transfer of transduced B-1 a cells into B cell-deficient recipient mice so that donor B-1 a cell migration and localization can be visualized. This protocol can be modified for other retroviral constructs and can be used in diverse functional assays post-adoptive transfer, including analysis of donor cell or host cell phenotype and function, or analysis of soluble factors secreted post B-1 a cell transfer. The use of distinct donor and recipient mice differentiated by CD45.1 and CD45.2 allotype and the presence of a GFP reporter within the retroviral plasmid could also enable detection of donor cells in other, immune-sufficient mouse models containing endogenous B cell populations.

In recent study published on Nature Medicine, Bockorny et al.1 performed a single-arm phase IIa trial (COMBAT study, NCT02826486) to evaluate safety, efficacy, immunobiological changes, and potential biomarkers for the CXCR4 inhibitor BL-8040, combined with a PD-1 antagonist (pembrolizumab) as a second-line or third-line treatment for patients with metastatic PDAC. This evidence translates the theory of reprogramming tumor immunosuppressive microenvironment into clinical practice and supports that targeting chemokines/chemokine receptors facilitates the immunotherapy of pancreatic ductal adenocarcinoma (Fig. 1).