CD45- erythroid progenitor cells promote lymph node metastasis in gastric cancer by inducing a hybrid epithelial/mesenchymal state in lymphatic endothelial cells.

BACKGROUND AND AIMS: Specific mechanisms of lymph node (LN) metastasis in early-stage gastric cancer (GC) have not been elucidated. The role of anemia, a vital clinical feature of GC, in LN metastasis is also unclear. Since the number of erythroid progenitor cells (EPCs) is increased in chronic anemia, we investigated its association with LN metastasis in GC. METHODS: Flow cytometry and immunofluorescence analyses were performed to sort and study EPCs from the circulation and tumors of patients with stage I-III GC. The effect of these EPCs on the activation of T and B cells and on the functions of lymphatic endothelial cells (LECs) was determined, and their ability to promote LN metastasis was evaluated using a footpad-popliteal LN metastasis model based on two human adenocarcinoma GC cell lines in nude mice. The prognostic value of EPCs was also analyzed. RESULTS: The proportion of CD45- EPCs was higher in the mononuclear cells in the circulation, tumors, and LNs of GC patients with LN metastasis (N+) than in those of GC patients without LN metastasis (N0). In N+ patients, CD45- EPCs were more abundant in metastatic LNs than in non-metastatic LNs. Lymphatic vessel endothelial hyaluronan receptor 1 immunoreactivity in tumors revealed that CD45- EPCs were positively associated with nodal stages and lymph vessel density. Furthermore, CD45- EPCs increased LEC proliferation and migration through their S100A8/A9 heterodimer-induced hybrid epithelial/mesenchymal (E/M) state; however, they did not influence the invasion and tubulogenesis of LECs or T and B cell proliferation. CD45- EPCs promoted LN metastasis in vivo; the S100A8/A9 heterodimer mimicked this phenomenon. Finally, CD45- EPCs predicted the overall and disease-free survival of stage I-III GC patients after radical resection. CONCLUSIONS: The CD45- EPCs accumulated in GC tissues and metastatic LNs and promoted LN metastasis via the S100A8/9-induced hybrid E/M state of LECs, which was the specific mechanism of LN metastasis in the early stages of GC.

Erythroid-transdifferentiated myeloid cells promote portal vein tumor thrombus in hepatocellular carcinoma.

Rationale: Hepatocellular carcinoma (HCC) is primarily characterized by a high incidence of vascular invasion. However, the specific mechanism underlying portal vein tumor thrombus (PVTT) in HCC remains unclear. As a consequence of myeloid cell developmental arrest, CD71+ erythroid progenitor cells (EPCs) and myeloid-derived suppressor cells play important roles in HCC; however, their roles in PVTT remain unclear. Methods: The role of CD71+ EPCs in the HCC tumor microenvironment (TME) was evaluated via morphological, RNA-sequencing, enzyme-linked immunosorbent assay, and flow cytometric analyses. Co-culture techniques were employed to assess the CD45+ EPCs and their vascular compromising effect. Additionally, the PVTT-promoting function of CD45+ EPCs was explored in vivo in a murine model. Results: The CD45+EPCs in HCC tissues exhibited increased myeloid cell features, including morphology, surface markers, transforming growth factor (TGF)-ß generation, and gene expression, compared with those in circulation. Hence, a large proportion of CD45+EPCs, particularly those in TMEs, comprise erythroid-transdifferentiated myeloid cells (EDMCs). Additionally, the expression of C-C chemokine receptor type 2 (CCR2) mRNA was upregulated in CD45+EPCs within the TME. Tumor macrophages from HCC tissues induced substantial migration of CD45+EPCs in a dose-dependent manner. Meanwhile, results from immunofluorescence analyses revealed that these two cell types are positively associated in the TME and circulation. That is, EDMCs are chemoattracted by HCC macrophages mainly via CCR2 from CD45+ EPCs in the circulation. Additionally, the expressions of FX, FVII, FGB, C4b, CFB, and CFH were elevated in CD45+EPCs within the TME compared with those in the spleen. The CD45+EPCs from the HCC TME promoted vessel endothelial cell migration and compromised tube formation through TGF-ß and FGB, respectively. Additionally, CD45+EPCs from the TME induced HCC cell migration. HCC macrophage-induced CD45+EPCs to exhibit higher levels of FX, FVII, FGB, and TGF-ß. Meanwhile, upregulation of CCAAT/enhancer binding protein beta expression induced FGB and TGF-ß generation in CD45+EPCs in the TME. WTAP, a major RNA m6A writer, stabilized FX and FVII mRNA and enhanced their nuclear export in CD45+EPCs from the TME. CD45+EPCs from the TME were positively associated with PVTT and poor prognosis. Splenectomy reduced the level of CD45+EPCs in the circulation and TME, as well as the incidence of microvascular invasion. The incidence of microvascular invasion increased following the transfer of HCC tissue CD45+EPCs to splenectomized HCC-bearing mice. Conclusions: The CD45+EPCs enriched in the HCC microenvironment are EDMCs, which are induced by HCC macrophages to migrate from the circulation to the TME. Subsequently, EDMCs promote PVTT by compromising the blood vessel endothelium, aggravating coagulation, and promoting HCC cell migration.

LAG3+ erythroid progenitor cells inhibit HBsAg seroclearance during finite pegylated interferon treatment through LAG3 and TGF-ß.

HBsAg seroclearance, the ideal aim of anti-hepatitis B virus (HBV) treatment, cannot be achieved easily. Anemia is another common issue for chronic hepatitis B (CHB) patients, which leads to elevation of erythroid progenitor cells (EPCs) and immune suppression in cancer. This study investigated the role of EPCs in HBsAg seroclearance following pegylated interferon-α (PEG-IFN) treatment. CD45+EPC accumulation in CHB patients and an AAV/HBV mice model was found in the circulation and liver by flow cytometry and immunofluorescence tests. Wright-Giemsa staining showed that these pathological CD45+EPCs presented elevated erythroid cells with relative immature morphologies and atypical cells compared with the control cells. CD45+EPCs were associated with immune tolerance and decreased HBsAg seroclearance during finite PEG-IFN treatment. CD45+EPCs suppressed antigen non-specific T cell activation and HBV-specific CD8+T cells, partially through transforming growth factor ß (TGF-ß). RNA-seq revealed that CD45+EPCs in patients with CHB presented a distinct gene expression profile compared with CD45-EPCs and CD45+EPCs from cord blood. Notably, CD45+EPCs from patients with CHB expressed high level of Lymphocyte-activation gene 3 (LAG3), an immune checkpoint molecule, and were then defined as LAG3+EPCs. LAG3+EPCs diminished the function of antigen presenting cells through LAG3, which was another mechanism by which LAG3+EPCs' suppressed HBV-specific CD8+T cells. Anti-LAG3 and anti-TGF-ß combination treatment decreased serum HBeAg, HBV DNA levels and HBsAg level, as well as HBsAg-expression in hepatocytes during PEG-IFN treatment in the AAV/HBV mice model. Conclusions: LAG3+EPCs inhibited the efficacy of PEG-IFN treatment on HBsAg seroclearance induced by LAG3 and TGF-ß. Anti-LAG3, anti-TGF-ß and PEG-IFN combination treatment might facilitate HBV clearance.