Characterization of autoimmune inflammation induced prostate stem cell expansion

Abstract

Background The presence of inflammation in prostate cancer (PCa) and benign prostate hyperplasia (BPH) has been well described but the cellular mechanisms by which inflammation modulates the prostate are currently unclear. Prostate stem cells (PSC) not only maintain prostate homeostasis but also are considered to be the cell of origin of PCa and an important contributor to BPH. However, the impact of inflammation on PSC is not well understood. Therefore, we initiated studies to evaluate the effect of inflammation on PSC. Method Ovalbumin specific CD8+ T cells were intravenously delivered to intact and castrated prostate ovalbumin expressing transgenic-3 (POET-3) mice to induce inflammation. Lin (CD45/CD31)−Sca1+CD49f+ cells (LSC) and progenitor cells within LSC were determined by flow cytometry. Sorted LSC were subjected to a prostate sphere forming assay to evaluate PSC clonal propagation, proliferation, immediate differentiation, and self-renewal ability. Density of individual spheres was measured by a cantilever-based resonator weighing system. Morphology and characterization of prostate spheres was determined by hematoxylin and eosin (H&E) staining and immunohistochemistry (IHC). Finally, immediate PSC differentiation in sphere formation was determined by immunofluorescence for epithelial cytokeratin markers cytokeratin (CK) 5 and CK8. Result Data presented here demonstrate a significant expansion of the proliferative (BrdU+) LSC population, including CK5+, p63+, CK18+ cells, as well as intermediate cells (CK5+/CK8+) in inflamed prostates. Histological images reveal that PSC from inflamed prostates produce significantly larger spheres, indicating that the enhanced proliferation observed in LSC is sustained in vitro in the absence of inflammatory mediators. In addition, cultures from inflamed PSC yielded increased number of tubule-like spheres. These tube-like spheres grown from PSCs isolated from inflamed mice exhibited stratification of a CK8+ luminal-like layer and a CK5+ basal-like layer. Notably, the numbers of spheres formed by inflamed and non-inflamed PSC were equal, suggesting that even though proliferation is enhanced by inflammation, the homeostatic level of PSC is maintained. Conclusion Induction of inflammation promotes PSC expansion and immediate differentiation through highly proliferative progenitor cells while the homeostasis of PSC is maintained.

The common parasite Toxoplasma gondii induces prostatic inflammation and microglandular hyperplasia in a mouse model

“…Importantly, chronic inflammation induced by bacterial models in non‐genetically modified mice are not fully penetrant, do not affect all lobes, and have not yet been fully characterized and quantified. Genetically engineered mice such as the POET‐3 autoimmune mouse model require particular background strains and back‐breeding of protein knockouts onto the genetic strain of inflammation, which is costly and time consuming . Additionally, hormone models yield many off‐target and systemic effects making data interpretation difficult.…”

“…Additionally, hormone models yield many off‐target and systemic effects making data interpretation difficult. Finally, each of the models produce variable responses …”

“…Mouse prostates were processed into single‐cell suspensions and intracellular and extracellular markers of interest were labeled as previously described . Before applying primary antibodies to the cells, non‐specific Fc Receptor binding was blocked using 0.5 μg/million cells of purified functional grade anti‐mouse CD16/CD32 (CAT#: 16‐0161, eBioscience) diluted in 100 μL of PBS, and incubated on ice for 30 min.…”

Distinct expression patterns of SULT2B1b in human prostate epithelium

“…The animal protocols used in this study were approved by Purdue Animal Care and Use Committee. The prostate stem cell population was isolated as previously described . Briefly, minced prostate tissue from 8 to 12 week‐old mice was digested with 1 mg/mL Collagenase‐I (Sigma‐Aldrich) in RPMI 1640 medium with 10% FBS for 2 hours, followed by trypsinization at 37°C.…”

Functional evidence that progenitor cells near sites of inflammation are precursors for aggressive prostate cancer

“…Previous studies in mouse models have demonstrated that acute inflammation promotes an expansion of progenitor-like cells, 8 and an increase in basal-to-luminal differentiation. 9 While we show that PIA-like luminal cells are enriched in regions of inflammation, an inability to study kinetic processes in human tissue prevents us from uncovering the sequence of events that links inflammation and PIA-like luminal progenitor cells.…”