Expressing IL-15/IL-18 and CXCR2 improve infiltration and survival of EGFRvIII-targeting CAR-T cells in breast cancer.

Previously, we have generated EGFRvIII-targeting CAR-T cells and brought hope for treating advanced breast cancer. However, EGFRvIII-targeting CAR-T cells were defined limited anti-tumor efficacy, which might be due to reduced accumulation, persistence of therapeutic T cells in tumor site of breast cancer. CXCLs were highly expressed in tumor environment of breast cancer and CXCR2 is the main receptor for CXCLs. Here, CXCR2 could significantly improve the trafficking and tumor specific accumulation of CAR-T cells both in vivo and in vitro. However, the anti-tumor effect of CXCR2 CAR-T cells were weaken which might be results of the apoptosis of T cells. Cytokines could stimulate Tcell proliferation, such as interleukin (IL)-15 and IL-18. Then, we generated CXCR2 CAR with synthetic IL-15 or IL-18 production. Co-expressing IL-15 or IL-18 could significantly suppress the exhaustion and apoptosis of T cells and enhanced the anti-tumor activity of CXCR2 CAR-T cells in vivo. Further, coexpression IL-15 or IL-18 in CXCR2 CAR-T cells did not cause toxicity. These findings provide a potential therapy strategy of co-expression IL-15 or IL-18 in CXCR2 CAR-T cells for the treatment of advancing breast cancer in the future.

LRRC25 plays a key role in all-trans retinoic acid-induced granulocytic differentiation as a novel potential leukocyte differentiation antigen

Leukocyte differentiation antigens (LDAs) play important roles in the immune system, by serving as surface markers and participating in multiple biological activities, such as recognizing pathogens, mediating membrane signals, interacting with other cells or systems, and regulating cell differentiation and activation. Data mining is a powerful tool used to identify novel LDAs from whole genome. LRRC25 (leucine rich repeat-containing 25) was predicted to have a role in the function of myeloid cells by a large-scale "omics" data analysis. Further experimental validation showed that LRRC25 is highly expressed in primary myeloid cells, such as granulocytes and monocytes, and lowly/intermediately expressed in B cells, but not in T cells and almost all NK cells. It was down-regulated in multiple acute myeloid leukemia (AML) cell lines and bone marrow cells of AML patients and up-regulated after all-trans retinoic acid (ATRA)-mediated granulocytic differentiation in AML cell lines and acute promyelocytic leukemia (APL; AML-M3, FAB classification) cells. Localization analysis showed that LRRC25 is a type I transmembrane molecule. Although ectopic LRRC25 did not promote spontaneous differentiation of NB4 cells, knockdown of LRRC25 by siRNA or shRNA and knockout of LRRC25 by the CRISPR-Cas9 system attenuated ATRA-induced terminal granulocytic differentiation, and restoration of LRRC25 in knockout cells could rescue ATRA-induced granulocytic differentiation. Therefore, LRRC25, a potential leukocyte differentiation antigen, is a key regulator of ATRA-induced granulocytic differentiation.