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Mesothelioma tumor cells modulate dendritic cell lipid content, phenotype and function.

Gardner JK, Mamotte CD, Patel P, Yeoh TL, Jackaman C, Nelson DJ - PLoS ONE (2015)

Bottom Line: Lipid accumulation was associated with reduced antigen processing ability (measured using a DQ OVA assay), upregulation of the co-stimulatory molecule, CD86, and production of the tolerogenic cytokine, IL-10.Moreover, increasing tumor burden was associated with reduced proliferation of tumor-antigen-specific CD8+ T cells in tumor-draining lymph nodes.This study shows that mesothelioma promotes DC lipid acquisition, which is associated with altered activation status and reduced capacity to process and present antigens, which may impair the ability of DCs to generate effective anti mesothelioma T cell responses.

View Article: PubMed Central - PubMed

Affiliation: Immunology and Cancer Group, School of Biomedical Sciences, Curtin University, Perth, Western Australia, Australia; CHIRI Biosciences Research Precinct, Curtin University, Perth, Western Australia, Australia.

ABSTRACT
Dendritic cells (DCs) play an important role in the generation of anti-cancer immune responses, however there is evidence that DCs in cancer patients are dysfunctional. Lipid accumulation driven by tumor-derived factors has recently been shown to contribute to DC dysfunction in several human cancers, but has not yet been examined in mesothelioma. This study investigated if mesothelioma tumor cells and/or their secreted factors promote increases in DC lipid content and modulate DC function. Human monocyte-derived DCs (MoDCs) were exposed to human mesothelioma tumor cells and tumor-derived factors in the presence or absence of lipoproteins. The data showed that immature MoDCs exposed to mesothelioma cells or factors contained increased lipid levels relative to control DCs. Lipid accumulation was associated with reduced antigen processing ability (measured using a DQ OVA assay), upregulation of the co-stimulatory molecule, CD86, and production of the tolerogenic cytokine, IL-10. Increases in DC lipid content were further enhanced by co-exposure to mesothelioma-derived factors and triglyceride-rich lipoproteins, but not low-density lipoproteins. In vivo studies using a murine mesothelioma model showed that the lipid content of tumor-infiltrating CD4+ CD8α- DCs, CD4- CD8α- DCs DCs and plasmacytoid DCs increased with tumor progression. Moreover, increasing tumor burden was associated with reduced proliferation of tumor-antigen-specific CD8+ T cells in tumor-draining lymph nodes. This study shows that mesothelioma promotes DC lipid acquisition, which is associated with altered activation status and reduced capacity to process and present antigens, which may impair the ability of DCs to generate effective anti mesothelioma T cell responses.

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Mesothelioma tumor cells modulate human MoDC lipid content and function.Human blood monocytes cultured with GM-CSF and IL-4 were exposed to varying ratios of JU77 mesothelioma tumor cells (A). At day 7, iMoDCs stained for CD11c expression and lipid levels using BODIPY were analysed by flow cytometry. Large cells were first gated (B) and CD11c+ DCs identified (unfilled line), relative to the isotype control (shaded area; C). The BODIPY mean fluorescence intensity (MFI) of CD11c+ DCs is proportional to intracellular lipid content (D). Pooled data shows lipid levels of iMoDCs co-cultured with varying ratios of JU77 tumor cells (E). During differentiation, DCs were also exposed to Met5A cells (at a ratio of 1DC: 10Met5A cells), and DC lipid content measured as BODIPY MFI (F). The DQ-OVA assay was used to measure the antigen processing ability of iMoDCs exposed to JU77 tumor cells (G). Data in (E) and (G) is from 6 individuals and data in (F) is from 2 individuals; all data shown as mean ± SEM. * = p < 0.05; ** = p < 0.005; *** = p < 0.0005.
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pone.0123563.g001: Mesothelioma tumor cells modulate human MoDC lipid content and function.Human blood monocytes cultured with GM-CSF and IL-4 were exposed to varying ratios of JU77 mesothelioma tumor cells (A). At day 7, iMoDCs stained for CD11c expression and lipid levels using BODIPY were analysed by flow cytometry. Large cells were first gated (B) and CD11c+ DCs identified (unfilled line), relative to the isotype control (shaded area; C). The BODIPY mean fluorescence intensity (MFI) of CD11c+ DCs is proportional to intracellular lipid content (D). Pooled data shows lipid levels of iMoDCs co-cultured with varying ratios of JU77 tumor cells (E). During differentiation, DCs were also exposed to Met5A cells (at a ratio of 1DC: 10Met5A cells), and DC lipid content measured as BODIPY MFI (F). The DQ-OVA assay was used to measure the antigen processing ability of iMoDCs exposed to JU77 tumor cells (G). Data in (E) and (G) is from 6 individuals and data in (F) is from 2 individuals; all data shown as mean ± SEM. * = p < 0.05; ** = p < 0.005; *** = p < 0.0005.

Mentions: A recent study showed that factors derived from several human and murine tumors promoted increased intracellular lipid levels in DCs, and that these lipid-laden DCs were functionally impaired [12]. Until now, no similar studies had been performed in mesothelioma. The first series of experiments examined the effect of human JU77 mesothelioma cells on the process of blood monocytes differentiating into immature human MoDCs (iMoDCs) using co-culture studies (Fig 1A). As a normal control, iMoDCs were also co-cultured with non-malignant Met5A cells, a human pleural mesothelial cell line. Following co-culture, the lipophilic fluorescent dye BODIPY 493/503 was used to measure iMoDC (Fig 1B–1D) and JU77 tumor cell lipid content (S1A and S1B Fig). Immature MoDCs exposed to JU77 tumor cells had significantly increased lipid content relative to DCs only; shown as mean fluorescence intensity (MFI; Fig 1E). Exposure to JU77 cells also promoted a greater increase in iMoDC lipid content compared to Met5A cells (Fig 1F). The lipid content of JU77 tumor cells co-cultured with iMoDCs did not change significantly relative to the JU77 only control (S1 C Fig).


Mesothelioma tumor cells modulate dendritic cell lipid content, phenotype and function.

Gardner JK, Mamotte CD, Patel P, Yeoh TL, Jackaman C, Nelson DJ - PLoS ONE (2015)

Mesothelioma tumor cells modulate human MoDC lipid content and function.Human blood monocytes cultured with GM-CSF and IL-4 were exposed to varying ratios of JU77 mesothelioma tumor cells (A). At day 7, iMoDCs stained for CD11c expression and lipid levels using BODIPY were analysed by flow cytometry. Large cells were first gated (B) and CD11c+ DCs identified (unfilled line), relative to the isotype control (shaded area; C). The BODIPY mean fluorescence intensity (MFI) of CD11c+ DCs is proportional to intracellular lipid content (D). Pooled data shows lipid levels of iMoDCs co-cultured with varying ratios of JU77 tumor cells (E). During differentiation, DCs were also exposed to Met5A cells (at a ratio of 1DC: 10Met5A cells), and DC lipid content measured as BODIPY MFI (F). The DQ-OVA assay was used to measure the antigen processing ability of iMoDCs exposed to JU77 tumor cells (G). Data in (E) and (G) is from 6 individuals and data in (F) is from 2 individuals; all data shown as mean ± SEM. * = p < 0.05; ** = p < 0.005; *** = p < 0.0005.
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pone.0123563.g001: Mesothelioma tumor cells modulate human MoDC lipid content and function.Human blood monocytes cultured with GM-CSF and IL-4 were exposed to varying ratios of JU77 mesothelioma tumor cells (A). At day 7, iMoDCs stained for CD11c expression and lipid levels using BODIPY were analysed by flow cytometry. Large cells were first gated (B) and CD11c+ DCs identified (unfilled line), relative to the isotype control (shaded area; C). The BODIPY mean fluorescence intensity (MFI) of CD11c+ DCs is proportional to intracellular lipid content (D). Pooled data shows lipid levels of iMoDCs co-cultured with varying ratios of JU77 tumor cells (E). During differentiation, DCs were also exposed to Met5A cells (at a ratio of 1DC: 10Met5A cells), and DC lipid content measured as BODIPY MFI (F). The DQ-OVA assay was used to measure the antigen processing ability of iMoDCs exposed to JU77 tumor cells (G). Data in (E) and (G) is from 6 individuals and data in (F) is from 2 individuals; all data shown as mean ± SEM. * = p < 0.05; ** = p < 0.005; *** = p < 0.0005.
Mentions: A recent study showed that factors derived from several human and murine tumors promoted increased intracellular lipid levels in DCs, and that these lipid-laden DCs were functionally impaired [12]. Until now, no similar studies had been performed in mesothelioma. The first series of experiments examined the effect of human JU77 mesothelioma cells on the process of blood monocytes differentiating into immature human MoDCs (iMoDCs) using co-culture studies (Fig 1A). As a normal control, iMoDCs were also co-cultured with non-malignant Met5A cells, a human pleural mesothelial cell line. Following co-culture, the lipophilic fluorescent dye BODIPY 493/503 was used to measure iMoDC (Fig 1B–1D) and JU77 tumor cell lipid content (S1A and S1B Fig). Immature MoDCs exposed to JU77 tumor cells had significantly increased lipid content relative to DCs only; shown as mean fluorescence intensity (MFI; Fig 1E). Exposure to JU77 cells also promoted a greater increase in iMoDC lipid content compared to Met5A cells (Fig 1F). The lipid content of JU77 tumor cells co-cultured with iMoDCs did not change significantly relative to the JU77 only control (S1 C Fig).

Bottom Line: Lipid accumulation was associated with reduced antigen processing ability (measured using a DQ OVA assay), upregulation of the co-stimulatory molecule, CD86, and production of the tolerogenic cytokine, IL-10.Moreover, increasing tumor burden was associated with reduced proliferation of tumor-antigen-specific CD8+ T cells in tumor-draining lymph nodes.This study shows that mesothelioma promotes DC lipid acquisition, which is associated with altered activation status and reduced capacity to process and present antigens, which may impair the ability of DCs to generate effective anti mesothelioma T cell responses.

View Article: PubMed Central - PubMed

Affiliation: Immunology and Cancer Group, School of Biomedical Sciences, Curtin University, Perth, Western Australia, Australia; CHIRI Biosciences Research Precinct, Curtin University, Perth, Western Australia, Australia.

ABSTRACT
Dendritic cells (DCs) play an important role in the generation of anti-cancer immune responses, however there is evidence that DCs in cancer patients are dysfunctional. Lipid accumulation driven by tumor-derived factors has recently been shown to contribute to DC dysfunction in several human cancers, but has not yet been examined in mesothelioma. This study investigated if mesothelioma tumor cells and/or their secreted factors promote increases in DC lipid content and modulate DC function. Human monocyte-derived DCs (MoDCs) were exposed to human mesothelioma tumor cells and tumor-derived factors in the presence or absence of lipoproteins. The data showed that immature MoDCs exposed to mesothelioma cells or factors contained increased lipid levels relative to control DCs. Lipid accumulation was associated with reduced antigen processing ability (measured using a DQ OVA assay), upregulation of the co-stimulatory molecule, CD86, and production of the tolerogenic cytokine, IL-10. Increases in DC lipid content were further enhanced by co-exposure to mesothelioma-derived factors and triglyceride-rich lipoproteins, but not low-density lipoproteins. In vivo studies using a murine mesothelioma model showed that the lipid content of tumor-infiltrating CD4+ CD8α- DCs, CD4- CD8α- DCs DCs and plasmacytoid DCs increased with tumor progression. Moreover, increasing tumor burden was associated with reduced proliferation of tumor-antigen-specific CD8+ T cells in tumor-draining lymph nodes. This study shows that mesothelioma promotes DC lipid acquisition, which is associated with altered activation status and reduced capacity to process and present antigens, which may impair the ability of DCs to generate effective anti mesothelioma T cell responses.

Show MeSH
Related in: MedlinePlus