Table_1_A Preclinical Model for the ATLL Lymphoma Subtype With Insights Into the Role of Microenvironment in HTLV-1-Mediated Lymphomagenesis.PDF

Adult T cell Leukemia/Lymphoma (ATLL) is a mature T cell malignancy associated with Human T cell Leukemia Virus type 1 (HTLV-1) infection. Among its four main clinical subtypes, the prognosis of acute and lymphoma variants remains poor. The long latency (3–6 decades) and low incidence (3–5%) of ATLL imply the involvement of viral and host factors in full-blown malignancy. Despite multiple preclinical and clinical studies, the contribution of the stromal microenvironment in ATLL development is not yet completely unraveled. The aims of this study were to investigate the role of the host microenvironment, and specifically fibroblasts, in ATLL pathogenesis and to propose a murine model for the lymphoma subtype. Here we present evidence that the oncogenic capacity of HTLV-1-immortalized C91/PL cells is enhanced when they are xenotransplanted together with human foreskin fibroblasts (HFF) in immunocompromised BALB/c Rag2-/-γc-/- mice. Moreover, cell lines derived from a developed lymphoma and their subsequent in vivo passages acquired the stable property to induce aggressive T cell lymphomas. In particular, one of these cell lines, C91/III cells, consistently induced aggressive lymphomas also in NOD/SCID/IL2Rγc KO (NSG) mice. To dissect the mechanisms linked to this enhanced tumorigenic ability, we quantified 45 soluble factors released by these cell lines and found that 21 of them, mainly pro-inflammatory cytokines and chemokines, were significantly increased in C91/III cells compared to the parental C91/PL cells. Moreover, many of the increased factors were also released by human fibroblasts and belonged to the known secretory pattern of ATLL cells. C91/PL cells co-cultured with HFF showed features reminiscent of those observed in C91/III cells, including a similar secretory pattern and a more aggressive behavior in vivo. On the whole, our data provide evidence that fibroblasts, one of the major stromal components, might enhance tumorigenesis of HTLV-1-infected and immortalized T cells, thus throwing light on the role of microenvironment contribution in ATLL pathogenesis. We also propose that the lymphoma induced in NSG mice by injection with C91/III cells represents a new murine preclinical ATLL model that could be adopted to test novel therapeutic interventions for the aggressive lymphoma subtype.

成人T细胞白血病/淋巴瘤（Adult T cell Leukemia/Lymphoma, ATLL）是一类与人类T细胞白血病病毒1型（Human T cell Leukemia Virus type 1, HTLV-1）感染相关的成熟T细胞恶性肿瘤。其四种主要临床亚型中，急性型和淋巴瘤型的预后仍较差。ATLL具有长达30~60年的长潜伏期，且发病率仅为3%~5%，提示病毒与宿主因素共同参与了完全恶性表型的形成。尽管已有多项临床前及临床研究，但基质微环境在ATLL发生发展中的作用尚未完全阐明。本研究旨在探讨宿主微环境（尤其是成纤维细胞）在ATLL发病机制中的作用，并为淋巴瘤亚型建立小鼠模型。本研究证实，将HTLV-1永生化的C91/PL细胞与人类包皮成纤维细胞（human foreskin fibroblasts, HFF）共同异种移植至免疫缺陷BALB/c Rag2-/-γc-/-小鼠体内时，其致瘤能力显著增强。此外，从形成的淋巴瘤中分离得到的细胞系及其后续体内传代株，均获得了稳定诱导侵袭性T细胞淋巴瘤的特性。其中一株C91/III细胞，可在NOD/SCID/IL2Rγc敲除（NOD/SCID/IL2Rγc KO, NSG）小鼠体内稳定诱导侵袭性淋巴瘤。为解析该增强致瘤能力的相关机制，我们对这些细胞系分泌的45种可溶性因子进行了定量分析，结果显示，与亲本C91/PL细胞相比，C91/III细胞中有21种因子（主要为促炎细胞因子与趋化因子）的表达水平显著升高。此外，许多上调的因子同时可由人类成纤维细胞分泌，且符合ATLL细胞已知的分泌谱特征。与HFF共培养的C91/PL细胞，也表现出与C91/III细胞相似的特征，包括类似的分泌谱及体内更具侵袭性的表型。综上，本研究数据证实，作为基质主要组成成分之一的成纤维细胞，可增强HTLV-1感染并永生化的T细胞的致瘤能力，从而阐明了微环境在ATLL发病机制中的作用。我们还提出，通过注射C91/III细胞在NSG小鼠体内诱导的淋巴瘤模型，可作为一种新型临床前ATLL模型，用于测试针对侵袭性淋巴瘤亚型的新型治疗干预手段。