Identification of HLA-DRB1*1501–Restricted T-cell Epitopes from Prostate-Specific Antigen

Mechanism of Androgen-Independent Stromal Proliferation in Benign Prostatic Hyperplasia

Benign prostatic hyperplasia (BPH) is a chronic proliferative disease showing stromal-dominant proliferation. However, the detailed proliferation mechanism has remained unclear. Although aging and androgen have been reported as definitive risk factors for BPH, recent studies have focused on the involvement of androgen-independent factors. Androgen-independent factors include ischemia, oxidative stress, metabolic syndrome, infection, autoimmune reactions, and inflammation, with inflammation in BPH tissues playing a central role in the BPH proliferative process. Inflammation in BPH tissues by various factors finally leads to tissue remodeling and stromal proliferation through the wound healing process of the prostate. To elucidate the proliferative mechanism of BPH, a study using whole-genome gene expression analysis in a stromal-dominant BPH rat model was performed and showed that immune response-related pathways and complement classical pathways are activated. Furthermore, expression analysis using this BPH rat model showed that the autoimmune reaction triggered complement pathway activation in the proliferative process of BPH. BPH is a multifactorial disease, and understanding the role of androgen-independent factors including immune responses contributes to elucidating the pathogenesis of BPH. Androgen-independent factors may lead to new therapeutic targets for BPH, and further development of this research is expected.

Anti-tumor effect of the alphavirus-based virus-like particle vector expressing prostate-specific antigen in a HLA-DR transgenic mouse model of prostate cancer

The goal of this study was to determine if an alphavirus-based vaccine encoding human Prostate-Specific Antigen (PSA) could generate an effective anti-tumor immune response in a stringent mouse model of prostate cancer. DR2bxPSA F1 male mice expressing human PSA and HLA-DRB1(*)1501 transgenes were vaccinated with virus-like particle vector encoding PSA (VLPV-PSA) followed by the challenge with Transgenic Adenocarcinoma of Mouse Prostate cells engineered to express PSA (TRAMP-PSA). PSA-specific cellular and humoral immune responses were measured before and after tumor challenge. PSA and CD8 reactivity in the tumors was detected by immunohistochemistry. Tumor growth was compared in vaccinated and control groups. We found that VLPV-PSA could infect mouse dendritic cells in vitro and induce a robust PSA-specific immune response in vivo. A substantial proportion of splenic CD8 T cells (19.6 ± 7.4%) produced IFNγ in response to the immunodominant peptide PSA(65-73). In the blood of vaccinated mice, 18.4 ± 4.1% of CD8 T cells were PSA-specific as determined by the staining with H-2D(b)/PSA(65-73) dextramers. VLPV-PSA vaccination also strongly stimulated production of IgG2a/b anti-PSA antibodies. Tumors in vaccinated mice showed low levels of PSA expression and significant CD8+ T cell infiltration. Tumor growth in VLPV-PSA vaccinated mice was significantly delayed at early time points (p=0.002, Gehan-Breslow test). Our data suggest that TC-83-based VLPV-PSA vaccine can efficiently overcome immune tolerance to PSA, mediate rapid clearance of PSA-expressing tumor cells and delay tumor growth. The VLPV-PSA vaccine will undergo further testing for the immunotherapy of prostate cancer.

Immunostimulatory early phenotype of tumor-associated macrophages does not predict tumor growth outcome in an HLA-DR mouse model of prostate cancer

Tumor-associated macrophages (TAM) were shown to support the progression of many solid tumors. However, anti-tumor properties of TAM were also reported in several types of cancer. Here, we investigated the phenotype and functions of TAM in two transgenic mouse models of prostate cancer that display striking differences in tumor growth outcome. Mice expressing prostate-specific antigen (PSA) as a self-antigen specifically in prostate (PSAtg mice) rejected PSA-expressing transgenic adenocarcinoma of mouse prostate (TRAMP) tumors. However, the introduction of HLA-DRB1*1501 (DR2b) transgene presenting PSA-derived peptides in a MHC class II-restricted manner exacerbated the growth of TRAMP-PSA tumors in DR2bxPSA F 1 mice. Despite the difference in tumor growth outcome, tumors in both strains were equally and intensively infiltrated by macrophages on the first week after tumor challenge. TAM exhibited mixed M1/M2 polarization and simultaneously produced pro-inflammatory (TNFα, IL1β) and anti-inflammatory (IL10) cytokines. TAM from both mouse strains demonstrated antigen-presenting potential and pronounced immunostimulatory activity. Moreover, they equally induced apoptosis of tumor cells. In vivo depletion of macrophages in DR2bxPSA F 1 but not PSAtg mice aggravated tumor growth suggesting that macrophages more strongly contribute to anti-tumor immunity when specific presentation of PSA to CD4+ T cells is possible. In summary, we conclude that in the early stages of tumor progression, the phenotype and functional properties of TAM did not predict tumor growth outcome in two transgenic prostate cancer models. Furthermore, we demonstrated that during the initial stage of prostate cancer development, TAM have the potential to activate T cell immunity and mediate anti-tumor effects.

High-throughput monitoring of human tumor-specific T-cell responses with large peptide pools

In immune intervention trials, the comprehensive investigation of immunogenicity or T-cell epitope-mapping is challenging especially when a large set of epitopes needs to be screened and limited sample material is available. To this end, T-cell responses are often monitored using peptide pools. Here, we assessed the magnitude and sensitivity of detection of antigen-specific CD8⁺ and CD4⁺ T cells using a single peptide alone or mixed into large pools. Interestingly the magnitude of ex vivo anti-viral and anti-tumor T-cell responses was identical irrespective of the presence and number of irrelevant peptides, in different functional assays with PBMCs from healthy donors and cancer patients. Moreover, the presence of up to 300 irrelevant peptides did not affect the threshold of responsiveness of antigen-specific CD8⁺ T cells to single cognate peptides. These data demonstrate the relevance of using very large peptide pools for the sensitive and specific immune-monitoring of epitope-specific T cells in natural or immune-modulated context.

Novel prostate acid phosphatase-based peptide vaccination strategy induces antigen-specific T-cell responses and limits tumour growth in mice

Treatment options for patients with advanced prostate cancer remain limited and rarely curative. Prostatic acid phosphatase (PAP) is a prostate-specific protein overexpressed in 95% of prostate tumours. An FDA-approved vaccine for the treatment of advanced prostate disease, PROVENGE® (sipuleucel-T), has been shown to prolong survival, however the precise sequence of the PAP protein responsible for the outcome is unknown. As the PAP antigen is one of the very few prostate-specific antigens for which there is a rodent equivalent with high homology, preclinical studies using PAP have the potential to be directly relevant to clinical setting. Here, we show three PAP epitopes naturally processed and presented in the context of HHDII/DR1 (114-128, 299-313, and 230-244). The PAP-114-128 epitope elicits CD4(+) and CD8(+) T-cell-specific responses in C57BL/6 mice. Furthermore, when immunised in a DNA vector format (ImmunoBody®), PAP-114-128 prevents and reduces the growth of transgenic adenocarcinoma of mouse prostate-C1 prostate cancer cell-derived tumours in both prophylactic and therapeutic settings. This anti-tumour effect is associated with infiltration of CD8(+) tumour-infiltrating lymphocytes and the generation of high avidity T cells secreting elevated levels of IFN-γ. PAP-114-128 therefore appears to be a highly relevant peptide on which to base vaccines for the treatment of prostate cancer.

Serum Antibody Repertoire Profiling Using In Silico Antigen Screen

Serum antibodies are valuable source of information on the health state of an organism. The profiles of serum antibody reactivity can be generated by using a high throughput sequencing of peptide-coding DNA from combinatorial random peptide phage display libraries selected for binding to serum antibodies. Here we demonstrate that the targets of immune response, which are recognized by serum antibodies directed against sequential epitopes, can be identified using the serum antibody repertoire profiles generated by high throughput sequencing. We developed an algorithm to filter the results of the protein database BLAST search for selected peptides to distinguish real antigens recognized by serum antibodies from irrelevant proteins retrieved randomly. When we used this algorithm to analyze serum antibodies from mice immunized with human protein, we were able to identify the protein used for immunizations among the top candidate antigens. When we analyzed human serum sample from the metastatic melanoma patient, the recombinant protein, corresponding to the top candidate from the list generated using the algorithm, was recognized by antibodies from metastatic melanoma serum on the western blot, thus confirming that the method can identify autoantigens recognized by serum antibodies. We demonstrated also that our unbiased method of looking at the repertoire of serum antibodies reveals quantitative information on the epitope composition of the targets of immune response. A method for deciphering information contained in the serum antibody repertoire profiles may help to identify autoantibodies that can be used for diagnosing and monitoring autoimmune diseases or malignancies.

A cytomegalovirus-based vaccine expressing a single tumor-specific CD8+ T-cell epitope delays tumor growth in a murine model of prostate cancer

Cytomegalovirus (CMV) is a highly immunogenic virus that results in a persistent, life-long infection in the host typically with no ill effects. Certain unique features of CMV, including its capacity to actively replicate in the presence of strong host CMV-specific immunity, may give CMV an advantage compared with other virus-based vaccine delivery platforms. In the present study, we tested the utility of mouse CMV (mCMV)-based vaccines expressing human prostate-specific antigen (PSA) for prostate cancer immunotherapy in double-transgenic mice expressing PSA and HLA-DRB1*1501 (DR2bxPSA F1 mice). We assessed the capacity of 2 mCMV-based vectors to induce PSA-specific CD8 T-cell responses and affect the growth of PSA-expressing Transgenic Adenocarcinoma of the Mouse Prostate tumors (TRAMP-PSA). In the absence of tumor challenge, immunization with mCMV vectors expressing either a H2-D(b)-restricted epitope PSA(65-73) (mCMV/PSA(65-73)) or the full-length gene for PSA (mCMV/PSA(FL)) induced comparable levels of CD8 T-cell responses that increased (inflated) with time. Upon challenge with TRAMP-PSA tumor cells, animals immunized with mCMV/PSA(65-73) had delay of tumor growth and increased PSA-specific CD8 T-cell responses, whereas animals immunized with mCMV/PSA(FL) showed progressive tumor growth and no increase in number of splenic PSA(65-73)-specific T cells. The data show that a prototype CMV-based prostate cancer vaccine can induce an effective antitumor immune response in a "humanized" double-transgenic mouse model. The observation that mCMV/PSA(FL) is not effective against TRAMP-PSA is consistent with our previous findings that HLA-DRB1*1501-restricted immune responses to PSA are associated with suppression of effective CD8 T-cell responses to TRAMP-PSA tumors.

Tumor-associated antigens for specific immunotherapy of prostate cancer

Prostate cancer (PCa) is the most common noncutaneous cancer diagnosis and the second leading cause of cancer-related deaths among men in the United States. Effective treatment modalities for advanced metastatic PCa are limited. Immunotherapeutic strategies based on T cells and antibodies represent interesting approaches to prevent progression from localized to advanced PCa and to improve survival outcomes for patients with advanced disease. CD8⁺ cytotoxic T lymphocytes (CTLs) efficiently recognize and destroy tumor cells. CD4⁺ T cells augment the antigen-presenting capacity of dendritic cells and promote the expansion of tumor-reactive CTLs. Antibodies mediate their antitumor effects via antibody-dependent cellular cytotoxicity, activation of the complement system, improving the uptake of coated tumor cells by phagocytes, and the functional interference of biological pathways essential for tumor growth. Consequently, several tumor-associated antigens (TAAs) have been identified that represent promising targets for T cell- or antibody-based immunotherapy. These TAAs comprise proteins preferentially expressed in normal and malignant prostate tissues and molecules which are not predominantly restricted to the prostate, but are overexpressed in various tumor entities including PCa. Clinical trials provide evidence that specific immunotherapeutic strategies using such TAAs represent safe and feasible concepts for the induction of immunological and clinical responses in PCa patients. However, further improvement of the current approaches is required which may be achieved by combining T cell- and/or antibody-based strategies with radio-, hormone-, chemo- or antiangiogenic therapy.

CD4 T-Cell-mediated immune response to prostatic proteins in HLA-DRB1*1503 transgenic mice and identification of a novel HLA-DRB1*1503-restricted T-cell epitope from human prostatic acid phosphatase

BACKGROUND

Transgenic mice engineered to express human leukocyte antigen (HLA) alleles are widely used for identification of immunogenic and naturally processed epitopes. Using HLA-DRB1*1501 (DR2b) transgenic mice, we have previously identified epitopes from two prostatic antigens, prostate-specific antigen (PSA) and prostatic acid phosphatase (PAP). These antigens are implicated in the development of autoimmunity in the prostate and also are considered promising targets for prostate cancer immunotherapy. HLA-DRB1*1501 is the most common DR15 allele in Caucasians, while HLA-DRB1*1503 is the most common in African Americans. Hence characterization of peptide immunogenicity for these alleles is important for the development of prostate cancer immunotherapy in white and black patients.

METHODS

HLA-DRB1*1501 or HLA-DRB1*1503 transgenic mice were immunized with human PSA or PAP. Libraries of overlapping 20-mer peptides spanning the entire sequences of these proteins were screened by IFN-γ ELISPOT assay.

RESULTS

PSA and PAP peptides that were previously identified in HLA-DRB1*1501 tg mice were immunogenic in HLA-DR1503 tg mice and induced CD4 T-cell response against whole processed PSA or PAP respectively. However, the hierarchy of the immunodominance among the peptides differed significantly between strains. Using HLA-DRB1*1503 tg mice, a novel immunogenic and naturally processed 20-mer peptide, PAP (233-252) has been identified that showed no reactivity in HLA-DRB1*1501 tg mice.

CONCLUSIONS

Our data demonstrate a disparity in CD4 T-cell immune reactivity to PSA and PAP between HLA-DRB1*1501 and -DRB1*1503 alleles in HLA transgenic mouse models. It is possible that such immunological differences could contribute to racial disparity in prostate cancer outcome.

T-cell recognition of prostatic peptides in men with chronic prostatitis/chronic pelvic pain syndrome

PURPOSE

A potential etiology of chronic prostatitis/chronic pelvic pain syndrome is autoimmunity. We determined whether T cells from men with chronic prostatitis/chronic pelvic pain syndrome would recognize peptides derived from the normal self-prostatic proteins prostate specific antigen and prostatic acid phosphatase.

MATERIALS AND METHODS

CD4 T cells purified from peripheral blood of 31 patients with chronic prostatitis/chronic pelvic pain syndrome and from the buffy coat preparation of 27 normal male blood donors were stimulated in vitro with a panel of immunogenic peptides from prostate specific antigen and prostatic acid phosphatase, and assayed for reactivity with the peptides by interferon-gamma enzyme-linked immunosorbent spot assay. Intermediate resolution HLA typing was done by polymerase chain reaction. Peptides were also tested by binding assay against different class II alleles.

RESULTS

Peptide PAP(173-192) was recognized more frequently by CD4 T cells from patients with chronic prostatitis/chronic pelvic pain syndrome than from healthy donors. The recognition of prostate specific antigen peptides was not statistically different when comparing cases to normal male blood donors individually. Peptide reactivity was more common in patients than in normal male blood donors for any prostate specific antigen peptide or any tested peptide. All peptides showed high promiscuity on binding assays. There was no association of cases with any specific HLA class II phenotype at intermediate resolution.

CONCLUSIONS

CD4 T cells from patients with chronic prostatitis/chronic pelvic pain syndrome have a higher rate of recognizing the self-prostatic proteins prostatic acid phosphatase and prostate specific antigen compared to those from normal male blood donors. Data provide further evidence to support the role of autoimmunity in some men with chronic prostatitis/chronic pelvic pain syndrome.

Chronic inflammation in the pathogenesis of benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is a common disorder affecting 50-80% of the aged male population. Androgens and age have been traditionally considered the main determinants of prostate enlargement, but in the last years a potentially important role of chronic inflammation in BPH pathogenesis has emerged. Bacterial and non-infectious chronic prostatitis could represent inciting factors leading to tissue hyperproliferation, possibly via the recently demonstrated antigen-presenting capacity of prostatic stromal cells, enabling them to induce and sustain intraglandular immune responses. The prostate growth-promoting chemokine IL-8 could represent a direct link between chronic prostate inflammation and autocrine/paracrine stromal cell proliferation, in agreement with its marked secretion induced in BPH stromal cells by a combination of Th1 and Th17 cell-derived inflammatory cytokines. BPH stromal cells express the vitamin D receptor (VDR), which is up-regulated by exposure to inflammatory stimuli. The non-hypercalcaemic VDR agonist elocalcitol, shown to arrest BPH development by decreasing the intra-prostatic androgen signalling without directly interfering with systemic androgen action, exerts immunoregulatory and anti-inflammatory properties in different prostatic pathology characterized by growth and inflammation. The mechanism of action of VDR agonists supports an important role of chronic inflammation in BPH pathogenesis and strengthens the concept of these agents as a therapeutic option for pharmacological treatment of BPH.

Cutting edge: permissive MHC class II allele changes the pattern of antitumor immune response resulting in failure of tumor rejection

We studied the growth of transgenic adenocarcinoma of mouse prostate (TRAMP)-C1 tumor cells expressing human prostate-specific Ag (PSA) in HLA-DRB1*1501 (DR2b) transgenic mice. TRAMP-PSA tumors were frequently rejected by HLA-DR2b(-) mice but had increased incidence in HLA-DR2b(+) littermates. The levels of PSA-specific CD8 T cell responses were significantly higher in the HLA-DR2b(-) mice that rejected TRAMP-PSA tumors compared with HLA-DR2b(+) tumor-bearing littermates. In contrast, Ab responses to PSA were strong in HLA-DR2b(+) mice bearing TRAMP-PSA tumors and were virtually undetectable in HLA-DR2b(-) littermates. The analysis of CD4 T cell responses to PSA revealed the presence of several CD4 T cell epitopes in HLA-DR2b(+) mice but failed to identify strong I-A(b)-restricted epitopes in HLA-DR2b(-) mice. Our data demonstrate that the expression of a permissive HLA class II allele can change the pattern of the immune response to a tumor Ag, resulting in the failure of tumor rejection.

HLA class II antigen presentation by prostate cancer cells

Prostate cancer is the second most commonly diagnosed cancer in men. Recent evidence suggests that reduced expression of target protein antigens and human leukocyte antigen (HLA) molecules is the predominant immune escape mechanism of malignant prostate tumor cells. The purpose of this study was to investigate the prospect of antigen specific immunotherapy against prostate cancer via the HLA class II pathway of immune recognition. Here, we show for the first time that prostate cancer cells express HLA class II proteins that are recognized by CD4+ T cells. Prostate tumor cells transduced with class II molecules efficiently presented tumor-associated antigens/peptides to CD4+ T cells. This data suggests that malignant prostate tumors can be targeted via the HLA class II pathway, and that class II-positive tumors could be employed for direct antigen presentation, and CD4+ T-cell mediated tumor immunotherapy.Prostate Cancer and Prostatic Diseases (2008) 11, 334-341; doi:10.1038/sj.pcan.4501021; published online 16 October 2007.

Spontaneous and Prostatic Steroid Binding Protein Peptide-Induced Autoimmune Prostatitis in the Nonobese Diabetic Mouse

Chronic nonbacterial prostatitis is a poorly defined syndrome of putative autoimmune origin. To further understand its pathogenesis, we have analyzed autoimmune prostatitis in the NOD mouse, a strain genetically prone to develop different organ-specific autoimmune diseases. Spontaneous development of autoimmune prostatitis in the NOD male, defined by lymphomonuclear cell infiltration in the prostate gland, is well-established by approximately 20 wk of age and is stably maintained afterward. Disease development is indistinguishable in NOD and NOR mice, but is markedly delayed in IFN-gamma-deficient NOD mice. A T cell response to the prostate-specific autoantigen prostatic steroid-binding protein (PSBP) can be detected in NOD males before development of prostate infiltration, indicating lack of tolerance to this self Ag. The intraprostatic inflammatory infiltrate is characterized by Th1-type CD4(+) T cells, which are able to transfer autoimmune prostatitis into NOD.SCID recipients. We characterize here experimental autoimmune prostatitis, detected by intraprostatic infiltrate and PSBP-specific T cell responses, induced in 6- to 8-wk-old NOD males by immunization with synthetic peptides corresponding to the C1 subunit of PSBP. Three PSBP peptides induce in NOD mice vigorous T and B cell responses, paralleled by a marked lymphomononuclear cell infiltration in the prostate. Two of these peptides, PSBP(21-40) and PSBP(61-80), correspond to immunodominant self epitopes naturally processed in NOD mice after immunization with PSBP, whereas peptide PSBP(91-111) represents a cryptic epitope. These model systems address pathogenetic mechanisms in autoimmune prostatitis and will facilitate testing and mechanistic analysis of therapeutic approaches in this condition.

Identification of HLA-DRB1*1501-restricted T-cell epitopes from human prostatic acid phosphatase

BACKGROUND

The crucial role of CD4 T-cells in anti-tumor immune response is widely recognized, yet the identification of HLA class II-restricted epitopes derived from tumor antigens has lagged behind compared to class I epitopes. This is particularly true for prostate cancer. Based on the hypothesis that successful cancer immunotherapy will likely resemble autoimmunity, we searched for the CD4 T-cell epitopes derived from prostatic proteins that are restricted by human leukocyte antigen (HLA)-DRB1*1501, an allele associated with granulomatous prostatitis (GP), a disease that may have an autoimmune etiology. One of the antigens implicated in the development of autoimmunity in the prostate is prostatic acid phosphatase (PAP), which is also considered a promising target for prostate cancer immunotherapy.

METHODS

We immunized transgenic (tg) mice engineered to express HLA-DRB1*1501 with human PAP. A library of overlapping 20-mer peptides spanning the entire human PAP sequence was screened in vitro for T-cell recognition by proliferative and interferon (IFN)-gamma enzyme-linked immunosorbent spot (ELISPOT) assays.

RESULTS

We identified two 20-mer peptides, PAP (133-152), and PAP (173-192), that were immunogenic and naturally processed from whole PAP in HLA-DRB1*1501 tg mice. These peptides were also capable of stimulating CD4 T lymphocytes from HLA-DRB1*1501-positive patients with GP and normal donors.

CONCLUSIONS

These peptides can be used for the design of a new generation of peptide-based vaccines against prostate cancer. The study can also be helpful in understanding the role of autoimmunity in the development of some forms of chronic prostatitis.

Vaccination therapy in prostate cancer

Radical prostatectomy and radiation therapy provide excellent localized prostate cancer (PC) control. Although the majority of prostate carcinoma is nowadays diagnosed at early stages with favourable risk features, in patients up to 30-40% it recurs within 10 years. Furthermore, the lack of effective therapies, once prostate carcinoma becomes refractory to androgen deprivation, mandates the development of alternative therapeutic options. There is a growing interest in harnessing the potency and specificity of anti-tumour immunity through the generation of fully competent dendritic cells and tumour reactive effector lymphocytes. Several strategies to treat or prevent the development of metastatic PC have been explored in clinical trials and are summarized in this review, considering also the feasibility and safety of these approaches. In some cases clinical responses were achieved showing that vaccine-primed T cells induced anti-tumour activity in vivo. The present findings and perspectives of the immunologic interventions in PC patients will be discussed.

Experimental rodent models of prostatitis: limitations and potential

Prostatitis is a polyetiological inflammation of the prostate gland in men characterized by pelvic pain, irritative voiding symptoms, and sexual dysfunction. Histologically prostatitis is characterized by poly- and mononuclear cell infiltrates (neutrophils, lymphocytes, macrophages and plasma cells) in the stromal connective tissue around the acini or ducts. Prostatitis is an important worldwide health problem in men. The pathogenesis and diagnostic criteria for the condition are obscure, with the result that the development of management programs for this condition has been hindered. Animal model(s) might be useful in elucidating mechanisms involved in the molecular pathogenesis of chronic nonbacterial prostatitis and chronic pelvic pain syndrome. Given that prostatitis might have a multifactorial etiology, several animal models with unique features may prove helpful. This review examines a number of experimental rodent models of prostatitis and evaluates their advantages and limitations.

Is benign prostatic hyperplasia (BPH) an immune inflammatory disease?

OBJECTIVES

Chronic inflammation has been documented for years in benign prostatic hyperplasia (BPH), but only now has it become evident as a major factor in disease progression. This review highlights the immunologic key features of chronic inflammation in BPH and the present interpretation of these changes in the development and progression of BPH.

RESULTS

Almost all BPH specimens show inflammatory infiltrates at histologic examination, but correlation to bacterial or other foreign antigens has not been established. Recognition of prostate secretion products by autoreactive T cells and animal models on experimental prostatitis demonstrate an autoimmune component to chronic inflammation. The infiltrate consists predominantly of chronically activated CD4(+) T lymphocytes, which are permanently recruited to prostate tissue via elevated expression of interleukin 15 (IL-15) and interferon gamma (IFN-gamma), proinflammatory cytokines produced by smooth muscle and T cells, respectively. With the appearance of infiltrates, T cell-derived cytokine production of IFN-gamma, IL-2, and transforming growth factor beta increases, the former two ultimately reaching 10-fold and the latter 2-fold higher levels in fully developed BPH than in normal prostates. As "mature" BPH nodules develop, IL-4 and IL-13 expression increases >2-fold, corresponding to a T-helper (Th)0/Th2 cytokine pattern. Dysregulation of the immune response in BPH may occur via elevated expression of proinflammatory IL-17, which stimulates a multifold production of IL-6 and IL-8, key executors of stromal growth in BPH.

CONCLUSIONS

These data strongly suggest that BPH is an immune inflammatory disease. Unravelling the specific nature of immune dysregulation may help design novel drugs with these specific targets in mind.