Tumor-Derived Granulocyte-Macrophage Colony-Stimulating Factor Regulates Myeloid Inflammation and T Cell Immunity in Pancreatic Cancer

“It has become widely appreciated that tumor-associated inflammation is an enabling characteristic of cancer and contributes to tumor escape from immune destruction (Hanahan and Weinberg, 2011).”

“…system by targeting Gr-1 + CD11b + cells or the cytokines that regulate their differentiation. comprised of precursors to macrophages, dendritic cells, and granulocytes at earlier stages of differentiation (Gabrilovich and Nagaraj, 2009; Ostrand-Rosenberg and Sinha, 2009; Peranzoni et al., 2010).”

“Disruption of CD8 immunity by elements of the tumor microenvironment is thought to be a major mechanism of tumor immune escape (Schreiber et al., 2011).”

“This approach led to sensitive (>95% of all pancreatic epithelial cells) and specific labeling of pancreas epithelial-derived cells, with no stromal cells labeled (Rhim et al., 2012).”

“…system by targeting Gr-1 + CD11b + cells or the cytokines that regulate their differentiation. comprised of precursors to macrophages, dendritic cells, and granulocytes at earlier stages of differentiation (Gabrilovich and Nagaraj, 2009; Ostrand-Rosenberg and Sinha, 2009; Peranzoni et al., 2010).”

“…2C) and produced high levels of nitrite upon culture (Figure 2D), suggesting expression of inducible nitric oxide synthase (iNOS); both arginase and iNOS have been previously linked to immunosuppression by Gr-1 + CD11b + cells in tumor-bearing mice (Bronte and Zanovello, 2005; Ma et al., 2011).”

“More likely in PDA, tumor-associated macrophages release IL-6 that directly affects the epithelium and promotes PanIN progression and PDA development in vivo (Beatty et al., 2011; Lesina et al., 2011).”

“To understand if CD8 T cells from GM-CSF knockdown tumors exhibited effector functions, we evaluated tumor-infiltrating CD8 T cells for their capacity to secrete IFN-g and mobilize CD107a, the latter serving as a biomarker of lytic function (Betts et al., 2003).”

“Other potential roles of Gr-1 + CD11b + cells in regulating tumor growth (Yang et al., 2004, 2008, 2011) appear therefore to be secondary or noncontributory to tumor growth, at least in this assay.”

“VEGF and granulocyte colony-stimulating factor (G-CSF) have also been implicated in MDSC development (Gabrilovich et al., 1998; Huang et al., 2007; Roland et al., 2009; Dolcetti et al., 2010).”

“…in patients with the same disease—the role of these cells remains controversial particularly with regard to the in vivo relevance of the T cell suppressive qualities that are typically demonstrated in vitro (Andreu et al., 2010; Clark et al., 2007; Melani et al., 2003; Stairs et al., 2011).”

“Other potential roles of Gr-1+ CD11b+ cells in regulating tumor growth (Yang et al., 2004, 2008, 2011) appear therefore to be secondary or noncontributory to tumor growth, at least in this assay.”

“Numerous studies have reported the expansion of Gr-1+ CD11b+ cells in a variety of implantable tumor models and have demonstrated the ability of these myeloid cells to impair T cell responses in vitro (Bronte et al., 2003; Kusmartsev et al., 2004; Sinha et al., 2005).”

“Indeed, our data are consistent with those of previous studies demonstrating IL-6 production primarily by stromal cells, not the tumor, in mouse models (Lesina et al., 2011) as well as human PDA (Bellone et al., 2006; Lesina et al., 2011).”

“Furthermore, normal pancreatic ductal cells also secreted VEGF (albeit somewhat less so than PDA cells) yet Gr-1 + CD11b + cells did not accumulate around normal ducts in vivo and conditioned media from normal ductal cells failed to support proliferation of c-kit + splenocytes into MDSC.”

“Stomach-specific expression of human IL-1b in transgenic mice leads to spontaneous gastric inflammation, invasive cancer, and mobilization of MDSC (Tu et al., 2008).”

“Importantly, our results are consistent with data described by Pylayeva-Gupta et al. (Pylayeva-Gupta et al., 2012).”

“…system by targeting Gr-1 + CD11b + cells or the cytokines that regulate their differentiation. comprised of precursors to macrophages, dendritic cells, and granulocytes at earlier stages of differentiation (Gabrilovich and Nagaraj, 2009; Ostrand-Rosenberg and Sinha, 2009; Peranzoni et al., 2010).”

“Mice lacking the IL-1 receptor exhibit delayed accumulation of MDSC and slower progression of implanted 4T1 mammary tumors and interestingly, these effects are partially restored by exogenous administration of IL-6, indicating that IL-6 may contribute independently to MDSC expansion (Bunt et al., 2007).”

“In genetically defined mouse models of cancer—which more closely recapitulate the tumor microenvironments observed in patients with the same disease—the role of these cells remains controversial particularly with regard to the in vivo relevance of the T cell suppressive qualities that are typically demonstrated in vit…”

“In studies of implantable tumormodels, GM-CSF has been linked to the generation of Gr-1 CD11b cells with immunosuppressive features (Bronte et al., 1999; Dolcetti et al., 2010; Morales et al., 2010; Serafini et al., 2004).”

“For example, the pro-inflammatory cytokine IL-1b has been implicated in MDSC pathophysiology such that fibrosarcoma or 4T1 mammary carcinoma cell lines engineered to secrete IL-1b grow more rapidly than control tumors upon implantation due to enhanced accumulation of Gr-1 CD11b and concomitant T cell suppression (Bunt…”

“In studies of implantable tumormodels, GM-CSF has been linked to the generation of Gr-1+ CD11b+ cells with immu- nosuppressive features (Bronte et al., 1999; Dolcetti et al., 2010; Morales et al., 2010; Serafini et al., 2004).”

“Recent studies have also linked the chemokine CCL21 to the appearance ofMDSC in the B16-F10 implantablemodel of melanoma (Shields et al., 2010), and other investigators have uncovered that IL-25 elicits a multipotent progenitor cell population in mucosal tissue that can differentiate into cells of various myeloid line…”

“In mice, IL-6 production can be induced in PDA tumor cells, or in pancreas epithelium harboring mutant Kras, but only after an acute inflammatory insult (Fukuda et al., 2011).”

“…a heterogeneous population of myeloid cells including myelocytes, metamyelocytes, band and segmented neutrophils, and monocytoid cells (Figure 1D), consistent with previous observations of cancer-associated Gr-1 + CD11b + cells (Andreu et al., 2010; Bronte et al., 2000; Stairs et al., 2011).”

“Numerous studies have reported the expansion of Gr-1 CD11b cells in a variety of implantable tumor models and have demonstrated the ability of these myeloid cells to impair T cell responses in vitro (Bronte et al., 2003; Kusmartsev et al., 2004; Sinha et al., 2005).”

“Numerous studies have reported the expansion of Gr-1 CD11b cells in a variety of implantable tumor models and have demonstrated the ability of these myeloid cells to impair T cell responses in vitro (Bronte et al., 2003; Kusmartsev et al., 2004; Sinha et al., 2005).”

“In studies of implantable tumormodels, GM-CSF has been linked to the generation of Gr-1 CD11b cells with immunosuppressive features (Bronte et al., 1999; Dolcetti et al., 2010; Morales et al., 2010; Serafini et al., 2004).”

“Various terms have been used in the literature to describe Gr-1 + CD11b + cells, including immature myeloid cells (Kusmartsev and Gabrilovich, 2006) or myeloid derived suppressor cells (MDSC) (Gabrilovich et al., 2007).”

“Furthermore, normal pancreatic ductal cells also secreted VEGF (albeit somewhat less so than PDA cells) yet Gr-1 + CD11b + cells did not accumulate around normal ducts in vivo and conditioned media from normal ductal cells failed to support proliferation of c-kit + splenocytes into MDSC.”

“…implicated in MDSC pathophysi- ology such that fibrosarcoma or 4T1 mammary carcinoma cell lines engineered to secrete IL-1b grow more rapidly than control tumors upon implantation due to enhanced accumulation of Gr-1+ CD11b+ and concomitant T cell suppression (Bunt et al., 2006; Song et al., 2005).”

“VEGF and granulocyte colony-stimulating factor (G-CSF) have also been implicated in MDSC development (Gabrilovich et al., 1998; Huang et al., 2007; Roland et al., 2009; Dolcetti et al., 2010).”

“Other potential roles of Gr-1 + CD11b + cells in regulating tumor growth (Yang et al., 2004, 2008, 2011) appear therefore to be secondary or noncontributory to tumor growth, at least in this assay.”

“In studies of implantable tumormodels, GM-CSF has been linked to the generation of Gr-1 CD11b cells with immunosuppressive features (Bronte et al., 1999; Dolcetti et al., 2010; Morales et al., 2010; Serafini et al., 2004).”

“VEGF and granulocyte colony-stimulating factor (G-CSF) have also been implicated in MDSC development (Gabrilovich et al., 1998; Huang et al., 2007; Roland et al., 2009; Dolcetti et al., 2010).”

“…in patients with the same disease—the role of these cells remains controversial particularly with regard to the in vivo relevance of the T cell suppressive qualities that are typically demonstrated in vitro (Andreu et al., 2010; Clark et al., 2007; Melani et al., 2003; Stairs et al., 2011).”

“…2C) and produced high levels of nitrite upon culture (Figure 2D), suggesting expression of inducible nitric oxide synthase (iNOS); both arginase and iNOS have been previously linked to immunosuppression by Gr-1 + CD11b + cells in tumor-bearing mice (Bronte and Zanovello, 2005; Ma et al., 2011).”

“Leukocytes infiltrating PDA lesions are predominantly derived from the innate immune system and coordinate a network of local immune suppression (Clark et al., 2007, 2009).”

“Indeed, our data are consistent with those of previous studies demonstrating IL-6 production primarily by stromal cells, not the tumor, in mouse models (Lesina et al., 2011) as well as human PDA (Bellone et al., 2006; Lesina et al., 2011).”

“Overexpression of IL-1b in the mouse pancreas results in pancreatitis but interestingly, not PanIN or PDA (Marrache et al., 2008).”

“In mice with combined loss of IFN-g, IL-3, and GM-CSF, lung carcinomas develop at a high frequency and exhibit an infiltrate of Gr-1 + CD11b + leukocytes (Dougan et al., 2011).”

“In addition, IL-6 expression in tumors may be silenced by DNA methylation (Dandrea et al., 2009).”

“In summary, our study, together with other ongoing efforts to elucidate pancreatic tumor immunity and immunotherapy (Bayne et al., 2012; Clark et al., 2007; Hiraoka et al., 2006; Roberts et al., 2013; Vonderheide et al., 2013), will likely offer insights into potential efficacy of combination…”