Pillai Manoj M, Iwata Mineo, Awaya Norihiro, Graf Lynn, Torok-Storb Beverly
Fred Hutchinson Cancer Research Center, 1100 Fairview Ave N, D1-100, PO Box 19024, Seattle, WA 98109-1024, USA.
Blood. 2006 May 1;107(9):3520-6. doi: 10.1182/blood-2005-10-4285. Epub 2006 Jan 3.
The marrow microenvironment consists of several different interacting cell types, including hematopoietic-derived monocyte/macrophages and nonhematopoietic-derived stromal cells. Gene-expression profiles of stromal cells and monocytes cultured together differ from those of each population alone. Here, we report that CXCL7 gene expression, previously described as limited to the megakaryocyte lineage, is expressed by monocytes cocultured with stromal cells. CXCL7 gene expression was confirmed by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), and secretion of protein was detected by enzyme-linked immunosorbent assay (ELISA) and Western blot. At least 2 stromal-derived activities, one yet to be identified, were required for optimal expression of CXCL7 by monocytes. NAP-2, the shortest form of CXCL7 detected in the coculture media, was confirmed to decrease the size and number of CFU-Meg colonies. The propeptide LDGF, previously reported to be mitogenic for fibroblasts, was not secreted by stimulated monocytes. The recombinant form of LDGF produced in a prokaryotic expression system did not have biologic activity in our hands. The monocytic source of CXCL7 was also detected by immunohistochemistry in normal bone marrow biopsies, indicating an in vivo function. We conclude that stromal-stimulated monocytes can serve as an additional source for CXCL7 peptides in the microenvironment and may contribute to the local regulation of megakaryocytopoiesis.
骨髓微环境由几种不同的相互作用细胞类型组成,包括造血来源的单核细胞/巨噬细胞和非造血来源的基质细胞。共同培养的基质细胞和单核细胞的基因表达谱与单独培养的每个细胞群体的基因表达谱不同。在这里,我们报告说,以前描述为仅限于巨核细胞系的CXCL7基因表达,在与基质细胞共培养的单核细胞中表达。通过定量逆转录聚合酶链反应(RT-PCR)确认CXCL7基因表达,并通过酶联免疫吸附测定(ELISA)和蛋白质印迹检测蛋白质分泌。单核细胞最佳表达CXCL7需要至少2种基质衍生活性,其中一种尚未确定。在共培养培养基中检测到的最短形式的CXCL7即NAP-2,被证实可减少CFU-Meg集落的大小和数量。以前报道对成纤维细胞有促有丝分裂作用的前肽LDGF,未被刺激的单核细胞分泌。在原核表达系统中产生的重组形式的LDGF在我们手中没有生物学活性。在正常骨髓活检中通过免疫组织化学也检测到CXCL7的单核细胞来源,表明其在体内的功能。我们得出结论,基质刺激的单核细胞可作为微环境中CXCL7肽的额外来源,并可能有助于巨核细胞生成的局部调节。