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Modulators of arginine metabolism support cancer immunosurveillance.

Capuano G, Rigamonti N, Grioni M, Freschi M, Bellone M - BMC Immunol. (2009)

Bottom Line: Tumor-associated accrual of myeloid derived suppressor cells (MDSC) in the blood, lymphoid organs and tumor tissues may lead to perturbation of the arginine metabolism and impairment of the endogenous antitumor immunity.Treatment of tumor-bearing mice with either the phosphodiesterase-5 inhibitor sildenafil or the nitric-oxide synthase (NOS) inhibitor L-NAME significantly restrained tumor growth and expanded the tumor-specific immune response.Our data emphasize the role of MDSC in modulating the endogenous tumor-specific immune response and underline the anti-neoplastic therapeutic potential of arginine metabolism modulators.

View Article: PubMed Central - HTML - PubMed

Affiliation: Cancer Immunotherapy and Gene Therapy Program, Istituto Scientifico San Raffaele, Via Olgettina 58, 20132, Milan, Italy. giusy_capuano@hotmail.com

ABSTRACT

Background: Tumor-associated accrual of myeloid derived suppressor cells (MDSC) in the blood, lymphoid organs and tumor tissues may lead to perturbation of the arginine metabolism and impairment of the endogenous antitumor immunity. The objective of this study was to evaluate whether accumulation of MDSC occurred in Th2 prone BALB/c and Th1 biased C57BL/6 mice bearing the C26GM colon carcinoma and RMA T lymphoma, respectively, and to investigate whether N(G) nitro-L-arginine methyl ester (L-NAME) and sildenafil, both modulators of the arginine metabolism, restored antitumor immunity.

Results: We report here that MDSC accumulate in the spleen and blood of mice irrespective of the mouse and tumor model used. Treatment of tumor-bearing mice with either the phosphodiesterase-5 inhibitor sildenafil or the nitric-oxide synthase (NOS) inhibitor L-NAME significantly restrained tumor growth and expanded the tumor-specific immune response.

Conclusion: Our data emphasize the role of MDSC in modulating the endogenous tumor-specific immune response and underline the anti-neoplastic therapeutic potential of arginine metabolism modulators.

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Treatments with L-NAME improves IFN-γ release. C57BL/6 mice were challenged with RMA cells and treated with L-NAME (E, F) or vehicle (V; panels C and D). After 15 days, animals were killed and their splenocytes were specifically restimulated in vitro. Blasts were tested for IFN-γ production (upon challenge with RMA or EL4G-) and analyzed by FACScalibur® after co-staining with mAb against CD8, CD44 and IFN-γ. Panel A and B report representative dot plot analyses of blasts from cultures of naïve splenocytes that were challenged with RMA (A) or EL4G- targets (B). The percentage of CD8+IFN-γ+ cells is reported in each panel as average ± SD of at least five animals for experimental group. The same data is reported in histogram G together with the statistical analysis. Student's T test: **0.001 < p < 0.05.
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Figure 7: Treatments with L-NAME improves IFN-γ release. C57BL/6 mice were challenged with RMA cells and treated with L-NAME (E, F) or vehicle (V; panels C and D). After 15 days, animals were killed and their splenocytes were specifically restimulated in vitro. Blasts were tested for IFN-γ production (upon challenge with RMA or EL4G-) and analyzed by FACScalibur® after co-staining with mAb against CD8, CD44 and IFN-γ. Panel A and B report representative dot plot analyses of blasts from cultures of naïve splenocytes that were challenged with RMA (A) or EL4G- targets (B). The percentage of CD8+IFN-γ+ cells is reported in each panel as average ± SD of at least five animals for experimental group. The same data is reported in histogram G together with the statistical analysis. Student's T test: **0.001 < p < 0.05.

Mentions: Our final goal was to investigate the effects of L-NAME on the endogenous tumor-specific immune response. RMA is an immunogenic tumor (i.e. upon in vivo growth it spontaneously induces an endogenous tumor-specific immune response [37]), whose immunogenicity is strongly biased by the expression of dominant viral antigens [38]. Hence, splenocytes recovered from L-NAME and vehicle-treated C57BL/6 mice bearing RMA tumors, were specifically restimulated in vitro and tested for their ability to recognize different targets. Flow cytometry analyses showed that cultures from L-NAME-treated mice contained a frequency of CD8+ T cells producing IFN-γ upon RMA challenge (Fig. 7E) higher than the one found in cultures from vehicle-treated mice (Fig. 7C). IFN-γ release was specific because the percentage of cells challenged with the irrelevant target EL4G- was at background level in both cultures (Fig. 7F and 7D). RMA-specific response was not due to a in vitro priming, because cells from naïve animals did not produce IFN-γ above background level when challenged with the targets (Fig. 7A and 7B).


Modulators of arginine metabolism support cancer immunosurveillance.

Capuano G, Rigamonti N, Grioni M, Freschi M, Bellone M - BMC Immunol. (2009)

Treatments with L-NAME improves IFN-γ release. C57BL/6 mice were challenged with RMA cells and treated with L-NAME (E, F) or vehicle (V; panels C and D). After 15 days, animals were killed and their splenocytes were specifically restimulated in vitro. Blasts were tested for IFN-γ production (upon challenge with RMA or EL4G-) and analyzed by FACScalibur® after co-staining with mAb against CD8, CD44 and IFN-γ. Panel A and B report representative dot plot analyses of blasts from cultures of naïve splenocytes that were challenged with RMA (A) or EL4G- targets (B). The percentage of CD8+IFN-γ+ cells is reported in each panel as average ± SD of at least five animals for experimental group. The same data is reported in histogram G together with the statistical analysis. Student's T test: **0.001 < p < 0.05.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2648942&req=5

Figure 7: Treatments with L-NAME improves IFN-γ release. C57BL/6 mice were challenged with RMA cells and treated with L-NAME (E, F) or vehicle (V; panels C and D). After 15 days, animals were killed and their splenocytes were specifically restimulated in vitro. Blasts were tested for IFN-γ production (upon challenge with RMA or EL4G-) and analyzed by FACScalibur® after co-staining with mAb against CD8, CD44 and IFN-γ. Panel A and B report representative dot plot analyses of blasts from cultures of naïve splenocytes that were challenged with RMA (A) or EL4G- targets (B). The percentage of CD8+IFN-γ+ cells is reported in each panel as average ± SD of at least five animals for experimental group. The same data is reported in histogram G together with the statistical analysis. Student's T test: **0.001 < p < 0.05.
Mentions: Our final goal was to investigate the effects of L-NAME on the endogenous tumor-specific immune response. RMA is an immunogenic tumor (i.e. upon in vivo growth it spontaneously induces an endogenous tumor-specific immune response [37]), whose immunogenicity is strongly biased by the expression of dominant viral antigens [38]. Hence, splenocytes recovered from L-NAME and vehicle-treated C57BL/6 mice bearing RMA tumors, were specifically restimulated in vitro and tested for their ability to recognize different targets. Flow cytometry analyses showed that cultures from L-NAME-treated mice contained a frequency of CD8+ T cells producing IFN-γ upon RMA challenge (Fig. 7E) higher than the one found in cultures from vehicle-treated mice (Fig. 7C). IFN-γ release was specific because the percentage of cells challenged with the irrelevant target EL4G- was at background level in both cultures (Fig. 7F and 7D). RMA-specific response was not due to a in vitro priming, because cells from naïve animals did not produce IFN-γ above background level when challenged with the targets (Fig. 7A and 7B).

Bottom Line: Tumor-associated accrual of myeloid derived suppressor cells (MDSC) in the blood, lymphoid organs and tumor tissues may lead to perturbation of the arginine metabolism and impairment of the endogenous antitumor immunity.Treatment of tumor-bearing mice with either the phosphodiesterase-5 inhibitor sildenafil or the nitric-oxide synthase (NOS) inhibitor L-NAME significantly restrained tumor growth and expanded the tumor-specific immune response.Our data emphasize the role of MDSC in modulating the endogenous tumor-specific immune response and underline the anti-neoplastic therapeutic potential of arginine metabolism modulators.

View Article: PubMed Central - HTML - PubMed

Affiliation: Cancer Immunotherapy and Gene Therapy Program, Istituto Scientifico San Raffaele, Via Olgettina 58, 20132, Milan, Italy. giusy_capuano@hotmail.com

ABSTRACT

Background: Tumor-associated accrual of myeloid derived suppressor cells (MDSC) in the blood, lymphoid organs and tumor tissues may lead to perturbation of the arginine metabolism and impairment of the endogenous antitumor immunity. The objective of this study was to evaluate whether accumulation of MDSC occurred in Th2 prone BALB/c and Th1 biased C57BL/6 mice bearing the C26GM colon carcinoma and RMA T lymphoma, respectively, and to investigate whether N(G) nitro-L-arginine methyl ester (L-NAME) and sildenafil, both modulators of the arginine metabolism, restored antitumor immunity.

Results: We report here that MDSC accumulate in the spleen and blood of mice irrespective of the mouse and tumor model used. Treatment of tumor-bearing mice with either the phosphodiesterase-5 inhibitor sildenafil or the nitric-oxide synthase (NOS) inhibitor L-NAME significantly restrained tumor growth and expanded the tumor-specific immune response.

Conclusion: Our data emphasize the role of MDSC in modulating the endogenous tumor-specific immune response and underline the anti-neoplastic therapeutic potential of arginine metabolism modulators.

Show MeSH
Related in: MedlinePlus