Ihedioha, O. | Search bioRxiv

bioRxiv2025

Platelet DKK1 promotes tolerogenic dendritic cells and non-healing responses in cutaneous leishmaniasis

Dickkopf-1(DKK1) is a classical Wnt antagonist, which is released at the initiation of Leishmania major infection through platelet TLR1/2 activation. Using BALB/c mice deficient in platelet MyD88 (MyD88PKO) or platelet DKK1 (DKK1PKO), we assessed whether the transmission of activation signals through MyD88 and subsequent release of DKK1 are critical in regulating the immune response to L. major. At the site of infection, the levels of neutrophil platelet aggregates and activated neutrophils of MyD88(PKO) and DKK1(PKO) mice were reduced. Further, these mice mounted anti-leishmanial Th1-responses and failed to develop progressive lesions. In contrast, WT BALB/c-infected mice developed progressive disease associated with elevated IL-10-producing Th1 and Th2 T cells. Further, elevated CD206+ M2 macrophages and tolerogenic DC-10 cells, which favor parasite proliferation, were observed. In vitro, DKK1 promoted DC IL-10 production and blocked TNF-induction of IL-12. Overall, these results indicate that platelet-DKK1 promotes disease progression through the induction of tolerogenic DCs and subsequent pathological Th2 and IL-10-Th1 T cell-responses. Summary statementPlatelet DKK1 produced in response to TLR1/2 signaling by Leishmania parasites drives development of non-healing responses. In vivo/ in vitro analyses indicate that the mechanism underlying this process is the promotion of tolerogenic dendritic cells, driving Th2 and Th1-IL-10 T cell responses. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=132 SRC="FIGDIR/small/656395v1_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@5b7049org.highwire.dtl.DTLVardef@128e273org.highwire.dtl.DTLVardef@12af4d2org.highwire.dtl.DTLVardef@12f10d2_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2024

Renal cancer cells acquire immune surface protein through trogocytosis and horizontal gene transfer

Trogocytosis is an underappreciated phenomenon that shapes the immune microenvironment surrounding many types of solid tumors. The consequences of membrane-bound proteins being deposited from a donor immune cell to a recipient cancer cell via trogocytosis are still unclear. Here, we report that human clear cell renal carcinoma tumors stably express the lymphoid markers CD45, CD56, CD14, and CD16. Flow cytometry performed on fresh kidney tumors revealed consistent CD45 expression on tumor cells, as well as varying levels of the other markers mentioned previously. These results were consistent with our immunofluorescent analysis, which also revealed colocalization of lymphoid markers with carbonic anhydrase 9 (CAIX), a standard kidney tumor marker. RNA analysis showed a significant upregulation of genes typically associated with immune cells in tumor cells following trogocytosis. Finally, we show evidence of chromosomal DNA being transferred from immune cells to tumor cells during trogocytosis. This horizontal gene transfer has transcriptional consequences in the recipient tumor cell, resulting in a fusion phenotype that expressed both immune and cancer specific proteins. This work demonstrates a novel mechanism by which tumor cell protein expression is altered through the acquisition of surface membrane fragments and genomic DNA from infiltrating lymphocytes. These results alter the way in which we understand tumor-immune cell interactions and may reveal new insights into the mechanisms by which tumors develop. Additionally, further studies into trogocytosis will help push the field towards the next generation of immunotherapies and biomarkers for treating renal cell carcinoma and other types of cancers. SIGNIFICANCE STATEMENTWe have identified trogocytosis as a mechanism by which human clear cell renal carcinoma tumors acquire lymphocyte surface protein expression from tumor infiltrating immune cells. In addition to the transfer of membrane fragments, we have provided evidence to show that genomic DNA is transferred from a normal immune cell to a tumor cell during trogocytosis. This process alters the transcriptome of cancer cells such that they express significantly more mRNA for immune proteins such as the lymphocyte marker CD45 compared to tumor cells that have not undergone trogocytosis. This study provides an in-depth analysis of the interactions between cancer cells and tumor infiltrating lymphocytes, and how these interactions alter the development of human tumors.

cancer biology↗