Prostate immunology: A challenging puzzle

Dissecting the immune suppressive human prostate tumor microenvironment via integrated single-cell and spatial transcriptomic analyses

The treatment of low-risk primary prostate cancer entails active surveillance only, while high-risk disease requires multimodal treatment including surgery, radiation therapy, and hormonal therapy. Recurrence and development of metastatic disease remains a clinical problem, without a clear understanding of what drives immune escape and tumor progression. Here, we comprehensively describe the tumor microenvironment of localized prostate cancer in comparison with adjacent normal samples and healthy controls. Single-cell RNA sequencing and high-resolution spatial transcriptomic analyses reveal tumor context dependent changes in gene expression. Our data indicate that an immune suppressive tumor microenvironment associates with suppressive myeloid populations and exhausted T-cells, in addition to high stromal angiogenic activity. We infer cell-to-cell relationships from high throughput ligand-receptor interaction measurements within undissociated tissue sections. Our work thus provides a highly detailed and comprehensive resource of the prostate tumor microenvironment as well as tumor-stromal cell interactions.

Therapeutic effects of β-caryophyllene on proliferative disorders and inflammation of the gerbil prostate

BACKGROUND

The prostate is susceptible to changes in androgen levels, which can play an important role in the development of Benign Prostatic Hyperplasia (BPH). Natural compounds have beneficial properties for organisms and can be an important therapeutic strategy in the treatment of diseases. β-Caryophyllene (BCP) is a phytocannabinoid present in several medicinal and food plants species and has shown beneficial effects in different organs. However, little is known about its effects on the prostate. The present study seeks to evaluate the effects of exposure to BCP on the morphophysiology of the ventral prostate of adult gerbils supplemented with testosterone.

METHODS

Animals were distributed into four groups (n = 8/group): Intact control (C); β-Caryophyllene (BCP): β-Caryophyllene (50 mg/kg/day); Testosterone (T): animals received subcutaneous injections of Testosterone Cypionate (3 mg/Kg), on alternate days, for one month and were euthanized 30 days supplementation ended; Testosterone and β-Caryophyllene (TBCP): animals were exposed to testosterone cypionate (3 mg/Kg) to induce hyperplastic alterations followed by daily BCP (50 mg/kg). Morphological, biometric, immunohistochemical, and serological analyses were performed.

RESULTS

Proliferative disorders and inflammatory foci were present in the ventral prostate of all experimental groups. An increase in the multiplicity of benign intraepithelial neoplasm and subepithelial inflammatory foci was observed in T group. The incidence of intraluminal inflammatory foci and microinvasive carcinoma was verified only in the T group. Cellular rearrangement and tissue remodeling occurred in the prostate of groups exposed to phytocannabinoids. A reduction was observed in the frequency of PHH3 and Cox2 markers in the prostatic epithelium of TBCP in comparison with T. A decrease in F4/80 and CD163 positive macrophages were also observed in the prostatic stroma of the TBCP group in comparison with T. The results suggest that BCP had favorable effects on BPH, reducing the proliferation and frequency of some inflammatory cells.

CONCLUSION

BCP impacts the tissue remodeling process in the premalignant prostate environment and that the use of this phytocannabinoid can have a promising effect in the handling of BPH.

Pattern recognition receptor-initiated innate immune responses in mouse prostatic epithelial cells‡

Three major pathogenic states of the prostate, including benign prostatic hyperplasia, prostate cancer, and prostatitis, are related to the local inflammation. However, the mechanisms underlying the initiation of prostate inflammation remain largely unknown. Given that the innate immune responses of the tissue-specific cells to microbial infection or autoantigens contribute to local inflammation, this study focused on pattern recognition receptor (PRR)-initiated innate immune responses in mouse prostatic epithelial cells (PECs). Primary mouse PECs abundantly expressed Toll-like receptor 3 (TLR3), TLR4, TLR5, melanoma differentiation-associated protein 5 (MDA5), and IFN-inducible protein 16 (p204 in mouse). These PRRs can be activated by their respective ligands: lipopolysaccharide (LPS) and flagellin of Gram-negative bacteria for TLR4 and TLR5, polyinosinic-polycytidylic acid (poly(I:C)) for TLR3 and MDA5, and herpes simplex virus DNA analog (HSV60) for p204. LPS and flagellin predominantly induced the expression of inflammatory cytokines, including tumor necrosis factor alpha (TNFA), interleukin 6 (IL6), chemokines monocyte chemoattractant protein-1 (MCP1), and C-X-C motif chemokine 10 (CXCL10). Poly(I:C) and HSV60 predominantly induced the expression of type 1 interferons (IFNA and IFNB) and antiviral proteins: Mx GTPase 1, 2',5'-oligoadenylate synthetase 1, and IFN-stimulated gene 15. The replication of mumps virus in PECs was inhibited by type 1 IFN signaling. These findings provide insights into the mechanisms underlying innate immune response in the prostate.

The pathological growth of the prostate gland in atherogenic contexts

The human prostate is an androgen-dependent gland where an imbalance in cell proliferation can lead to benign prostatic hyperplasia (BPH), which results in voiding lower urinary tract symptoms in the elderly. In the last decades, novel evidence has suggested that BPH might represent an element into the wide spectrum of disorders conforming the Metabolic Syndrome (MS). The dyslipidemic state and the other atherogenic factors of the MS have been shown to induce, maintain and/or aggravate the pathological growth of different organs, with data regarding the prostate being still limited. We here review the available epidemiological and experimental studies about the association of BPH with dyslipidemias. In particular, we have focused on Oxidized Low-Density Lipoproteins (OxLDL) as a potential trigger for vascular disease and cellular proliferation in atherogenic contexts, analyzing their putative molecular mechanisms, including the induction of specific extracellular vesicles (EVs)-derived miRNAs. In addition to the epidemiological evidence, OxLDL is proposed to play a fundamental role in the upregulation of prostatic cell proliferation by activating the Rho/Akt/p27^Kip1 pathway in atherogenic contexts. miR-21, miR-141, miR-143, miR-145, miR-155, and miR-221 would be involved in the transcription of genes related to the proliferative process. Although much remains to be investigated regarding the impact of OxLDL, its receptors, and molecular mechanisms on the prostate, it is clear that EVs and miRNAs represent a promising target for proliferative pathologies of the prostate gland.