Sex steroid modulation of macrophages within the prostate tumor microenvironment

BACKGROUND

The role of androgens and other sex steroids is known to influence the prognosis and progression of prostate cancer through different disease states. While androgens are generally regarded as immunosuppressive and estrogens as inflammatory, the specific influence of sex steroids on the immune microenvironment of prostate tumors remains incompletely understood.

MATERIAL AND METHODS

In this study, we evaluate the link between sex steroids and prostate cancer immune cells, particularly macrophages. Using in vitro and in vivo models, as well as ex vivo culture of patient prostate tissue, we evaluated the influence of androgen, estrogen, and progesterone on immune cells of the prostate microenvironment.

RESULTS

In vitro, we observed sex steroids induced indirect changes on prostate cancer cell proliferation via THP-1 derived macrophages, but no clear changes were induced using human monocyte derived macrophages. Comparing immunohistochemistry for immunosuppressive macrophage marker CD163 with concomitant circulating sex steroids from the same patients, we observed a correlation with higher dehydroepiandrosterone (DHEA)-sulfate and estrone-sulfate levels associated with higher prostate CD163 expression. Similar relationships between DHEA and CD163 levels were observed in ex vivo cultured prostate biopsies. Finally, in a murine prostate cancer model of long-term sex steroids we observed significant differences in tumor growth in mice implanted with estrogen and DHEA diffusion tubes.

CONCLUSIONS

Our results highlight the complex influence of sex steroids on the immune cell composition of prostate tumors. Understanding this biology may help to further personalized therapy and improve patient outcomes.

Subversion of infiltrating prostate macrophages to a mixed immunosuppressive tumor-associated macrophage phenotype

Tumor-associated macrophages (TAMs) support tumor progression within the tumor microenvironment (TME). Many questions remain as to the origin, development, and function of TAMs within the prostate TME. Evaluation of TAMs in prostate cancer (PCa) patients identified the immunosuppressive TAM marker CD163 in adjacent normal epithelium as an independent predictor of metastases or PCa death. Flow cytometry analyses identified prostate TAMs as frequently expressing both proinflammatory M1 (CCR7+) and immunosuppressive M2 (CD163+) markers. In vitro, we demonstrate PCa cells similarly subvert human M1 macrophages toward a mixed M1/M2 macrophage phenotype favoring tumor growth. Further the cytokine milieu-induced transition between immunosuppressive M2 to proinflammatory M1 (M2→M1) macrophages is abrogated by the presence of PCa cells. RNA sequencing suggests alterations in chemokine expression in prostate TAMs due to the presence of PCa cells. Together, our results suggest that prostate TAMs originate from inflammatory infiltrating macrophages, which are then reprogrammed mainly by PCa cells, but also the cytokine milieu. A better understanding of this subversion of macrophages within the prostate may lead to novel treatment strategies.

Efficiency of human monocyte-derived suppressor cell-based treatment in graft-versus-host disease prevention while preserving graft-versus-leukemia effect

Background

Immunosuppressive cell-based therapy is a recent strategy for controlling Graft-versus-Host Disease (GvHD). Such cells ought to maintain their suppressive function in inflammatory conditions and in the presence of immunosuppressive agents currently used in allogeneic hematopoietic cell transplantation (allo-HCT). Moreover, these therapies should not diminish the benefits of allo-HCT, the Graft-versus-Leukemia (GvL) effect. We have previously reported on a novel subset of human monocyte-derived suppressor cells (HuMoSC) as a prospective approach for controlling GvHD.Objective

The objective of this study was to explore the therapeutic relevance of the HuMoSC in clinical conditions.

Methods

Immune regulatory functions of HuMoSC were assessed in inflammatory conditions and in the presence of immunosuppressants. The therapeutic efficiency of the association of HuMoSC with immunosuppressants was evaluated in an experimental model of GvHD induced by human PBMC in NOD/SCID/IL2-Rγ_c^−/− (NSG) mice.

Interestingly, the inhibitory functions of HuMoSC against T lymphocytes and their ability to polarize Treg are preserved, in vitro, in inflammatory environments and are not affected by immunosuppressive agents. In vivo, the association of HuMoSC-based treatment with an immunosuppressive drug showed a synergistic effect for controlling GvHD. Furthermore, HuMoSC control GvHD while preserving GvL effect in a xeno-GvHD conditioned mouse model with cell neoplasm (CAL-1). HuMoSC are generated according to good manufacturing practices (GMP) and we demonstrated that these cells tolerate long-term preservation with unaltered phenotype and function.Conclusion

HuMoSC-based therapy represents a promising approach for controlling GvHD and could be quickly implemented in clinical practice.

Sex steroids in the tumor microenvironment and prostate cancer progression

Prostate cancer is uniquely dependent on androgens. Despite years of research on the relationship between androgens and prostate cancer, many questions remain as to the biological effects of androgens and other sex steroids during prostate cancer progression. This article reviews the clinical and basic research on the influence of sex steroids such as androgens, estrogens and progesterone within the prostate tumor microenvironment on the progression of prostate cancer. We review clinical studies to date evaluating serum sex steroids as prognostic biomarkers and discuss their respective biological effects within the prostate tumor microenvironment. We also review the link between genomic alterations and sex steroid levels within prostate tumors. Finally, we highlight the links between sex steroid levels and the function of the immune system within the tumor microenvironment. As the context of treatment of lethal prostate cancer evolves over time, an understanding of this underlying biology remains central to developing optimal treatment approaches.