Project Summary/Abstract
Prostate organogenesis starts prior to birth, with extensive tissue growth occurring during puberty in response
to androgens after the immune system is fully functional. Androgens are generally considered immune-
suppressive, so this suggests contradictory roles for immune cells in the prostate, where an immune suppressive
microenvironment is needed as new prostate-specific proteins are generated, yet immune cell functions are
required to promote morphogenesis and tissue growth during puberty. Our recent single-cell RNA sequencing
analyses of normal mouse and human prostates revealed previously unknown heterogeneity in prostate
epithelial cell types. These studies form the foundation for a new direction in which I propose to shift my focus
from prostate epithelial cells to investigate the function, developmental origins, and androgen-dependence of
immune cells in the prostate. The long-term goal of this research is to investigate immune cell regulation of
prostate organogenesis so that we can better understand the underpinnings of benign prostate disease. This
application specifically seeks to elucidate the function of macrophages during prostate organogenesis and their
potential contribution to BPH progression. Our central hypothesis is that heterogeneous populations of prostate
macrophages with distinct cellular origins and tissue-specific properties regulate the organogenesis and function
of the prostate, and their dysregulation contributes to BPH. To test our hypothesis, Specific Aim 1 will identify
the function and heterogeneity of macrophages in the developing prostate. Specific Aim 2 will determine the
cellular origins of macrophages in the developing prostate and in BPH. Specific Aim 3 will identify the androgen
signaling requirements of macrophage populations in the developing prostate and in BPH. Under Aim 1, we will
conduct immunofluorescence analysis of macrophages in prostate tissues, incorporating high-resolution 3D
imaging, live imaging, and data from single-cell RNA sequencing. For Aim 2, we will conduct genetic-lineage
tracing studies of macrophages of yolk sac, fetal liver, and bone marrow origin. For Aim 3, we will test the role
of AR in prostate macrophages by deleting AR in macrophages during prostate organogenesis and in a mouse
model of BPH. This proposal is innovative due to the novel investigation into how immune cells contribute to
promoting prostate organogenesis both prior to and during puberty in this androgen-regulated organ; the novel
investigation into how AR functions in prostate immune cells to regulate organ morphogenesis and immune
suppression during puberty; and the use of innovative technology. The proposed research is significant because
successful completion of this proposal will elucidate the in vivo function of macrophages during prostate
organogenesis; demonstrate the cellular origin of prostate macrophages across the various stages of prostate
organogenesis; and clarify the in vivo role of cell-autonomous AR in macrophages during prostate
organogenesis. Importantly, this project will further investigate the role of macrophages in the development of
BPH, which has the potential to inform the development of improved treatment strategies for BPH.