Macrophages of multiple hematopoietic origins reside in the developing prostate

Tissue-resident macrophages contribute to the organogenesis of many tissues. Growth of the prostate is regulated by androgens during puberty, yet androgens are considered immune suppressive. In this study, we characterized the localization, androgen receptor expression and hematopoietic origin of prostate macrophages, and transiently ablated macrophages during postnatal prostate organogenesis in the mouse. We show that myeloid cells were abundant in the prostate during puberty. However, nuclear androgen receptor expression was not detected in most macrophages. We found Cx3cr1, a marker for macrophages, monocytes and dendritic cells, expressed in interstitial macrophages surrounding the prostate and associated with nerve fibers. Furthermore, we provide evidence for the co-existence of embryonic origin, self-renewing, tissue-resident macrophages and recruited macrophages of bone-marrow monocyte origin in the prostate during puberty. Our findings suggest that prostate macrophages promote neural patterning and may shed further light on our understanding of the role of the innate immune system in prostate pathology in response to inflammation and in cancer.