Plasma concentration of Propionibacterium acnes antibodies and prostate cancer risk: results from an Australian population-based case-control study

Integrative Metatranscriptomic Analysis Reveals Disease-specific Microbiome-host Interactions in Oral Squamous Cell Carcinoma

Studies on the microbiome of oral squamous cell carcinoma (OSCC) have been limited to 16S rRNA gene sequencing. Here, laser microdissection coupled with brute-force, deep metatranscriptome sequencing was employed to simultaneously characterize the microbiome and host transcriptomes and predict their interaction in OSCC. The analysis involved 20 HPV16/18-negative OSCC tumor/adjacent normal tissue pairs (TT and ANT) along with deep tongue scrapings from 20 matched healthy controls (HC). Standard bioinformatic tools coupled with in-house algorithms were used to map, analyze, and integrate microbial and host data. Host transcriptome analysis identified enrichment of known cancer-related gene sets, not only in TT versus ANT and HC, but also in the ANT versus HC contrast, consistent with field cancerization. Microbial analysis identified a low abundance yet transcriptionally active, unique multi-kingdom microbiome in OSCC tissues predominated by bacteria and bacteriophages. HC showed a different taxonomic profile yet shared major microbial enzyme classes and pathways with TT/ANT, consistent with functional redundancy. Key taxa enriched in TT/ANT compared with HC were Cutibacterium acnes, Malassezia restricta, Human Herpes Virus 6B, and bacteriophage Yuavirus. Functionally, hyaluronate lyase was overexpressed by C. acnes in TT/ANT. Microbiome-host data integration revealed that OSCC-enriched taxa were associated with upregulation of proliferation-related pathways. In a preliminary in vitro validation experiment, infection of SCC25 oral cancer cells with C. acnes resulted in upregulation of MYC expression. The study provides a new insight into potential mechanisms by which the microbiome can contribute to oral carcinogenesis, which can be validated in future experimental studies.

Significance

Studies have shown that a distinct microbiome is associated with OSCC, but how the microbiome functions within the tumor interacts with the host cells remains unclear. By simultaneously characterizing the microbial and host transcriptomes in OSCC and control tissues, the study provides novel insights into microbiome-host interactions in OSCC which can be validated in future mechanistic studies.

Cutaneous melanoma, prostate-specific antigen testing and the subsequent risk of prostate cancer diagnosis: a prospective analysis of the 45 and Up Study

BACKGROUND

The association between cutaneous melanoma and subsequent risk of prostate cancer (PC) was examined in a large population-based cohort study.

METHODS

Male participants in the Sax Institute's 45 and Up Study (Australia) were recruited between 2006 and 2009. Questionnaire data and linked administrative health data from the Centre for Health Record Linkage and Services Australia identified melanomas diagnosed between 1/1/1994 and 12 months before Study recruitment (i.e., between 2005 and 2008), incident PCs, primary healthcare utilisation and prostate-specific antigen (PSA) tests. Men were excluded from the current analyses if they had a recorded PC or other cancer diagnosis other than melanoma and non-melanoma skin cancer prior to recruitment. Multivariable Cox regression was used to estimate hazard ratios (HRs) adjusting for PSA-testing frequency before PC diagnosis.

RESULTS

Of 96,548 eligible men, 1899 were diagnosed with melanoma during the melanoma diagnosis period and 3677 incident PC diagnosed during follow-up (latest date 31/12/2013). Men with melanoma diagnosis had increased risk of a subsequent PC diagnoses (vs. no melanoma; fully adjusted HR = 1.32; 95% CI: 1.09-1.60). There was weak evidence of higher risks of a subsequent PC diagnosis for men diagnosed with more than one melanoma compared to men diagnosed with only one melanoma (p = 0.077), and if first melanoma diagnosis was 10 to 15 years before Study recruitment (fully adjusted HR = 2.05; 95% CI [1.35, 3.12]).

CONCLUSION

Melanoma diagnosis was associated with increased risk of subsequent PC diagnosis, after adjusting for PSA testing and primary healthcare utilisation. While our ability to adjust for PC screening reduced risk of detection bias, we acknowledge that residual confounding from increased medical surveillance after melanoma diagnoses cannot be entirely ruled out.

Multiple pathogens and prostate cancer

BACKGROUND

The aim of this review is to consider whether multiple pathogens have roles in prostate cancer.

METHODS

We have reviewed case control studies in which infectious pathogens in prostate cancer were compared to normal and benign prostate tissues. We also reviewed additional evidence from relevant published articles.

RESULTS

We confirmed that high risk human papilloma viruses are a probable cause of prostate cancer. We judged Escherichia coli, Cutibacterium acnes, Neisseria gonorrhoea, Herpes simplex, Epstein Barr virus and Mycoplasmas as each having possible but unproven roles in chronic prostatic inflammation and prostate cancer. We judged Cytomegalovirus, Chlamydia trachomatis, Trichomonas vaginalis and the Polyoma viruses as possible but unlikely to have a role in prostate cancer.

CONCLUSIONS AND ACTIONS

The most influential cause of prostate cancer appears to be infection induced chronic inflammation. Given the high prevalence of prostate cancer it is important for action to can be taken without waiting for additional conclusive evidence. These include: 1. Encouragement of all boys (as well as girls) to have HPV vaccines 2. The vigorous use of antibiotics to treat all bacterial pathogens identified in the urogenital tract 3. The use of antiviral medications to control herpes infections 4. Education about safe sexual practices.

Bacteria-Mediated Oncogenesis and the Underlying Molecular Intricacies: What We Know So Far

Cancers are known to have multifactorial etiology. Certain bacteria and viruses are proven carcinogens. Lately, there has been in-depth research investigating carcinogenic capabilities of some bacteria. Reports indicate that chronic inflammation and harmful bacterial metabolites to be strong promoters of neoplasticity. Helicobacter pylori-induced gastric adenocarcinoma is the best illustration of the chronic inflammation paradigm of oncogenesis. Chronic inflammation, which produces excessive reactive oxygen species (ROS) is hypothesized to cause cancerous cell proliferation. Other possible bacteria-dependent mechanisms and virulence factors have also been suspected of playing a vital role in the bacteria-induced-cancer(s). Numerous attempts have been made to explore and establish the possible relationship between the two. With the growing concerns on anti-microbial resistance and over-dependence of mankind on antibiotics to treat bacterial infections, it must be deemed critical to understand and identify carcinogenic bacteria, to establish their role in causing cancer.

A review of microscopy-based evidence for the association of Propionibacterium acnes biofilms in degenerative disc disease and other diseased human tissue

PURPOSE

Recent research shows an increasing recognition that organisms not traditionally considered infectious in nature contribute to disease processes. Propionibacterium acnes (P. acnes) is a gram-positive, aerotolerant anaerobe prevalent in the sebaceous gland-rich areas of the human skin. A ubiquitous slow-growing organism with the capacity to form biofilm, P. acnes, recognized for its role in acne vulgaris and medical device-related infections, is now also linked to a number of other human diseases. While bacterial culture and molecular techniques are used to investigate the involvement of P. acnes in such diseases, definitive demonstration of P. acnes infection requires a technique (or techniques) sensitive to the presence of biofilms and insensitive to the presence of potential contamination. Fortunately, there are imaging techniques meeting these criteria, in particular, fluorescence in situ hybridization and immunofluorescence coupled with confocal laser scanning microscopy, as well as immunohistochemistry.

METHODS

Our literature review considers a range of microscopy-based studies that provides definitive evidence of P. acnes colonization within tissue from a number of human diseases (acne vulgaris, degenerative disc and prostate disease and atherosclerosis), some of which are currently not considered to have an infectious etiology.

RESULTS/CONCLUSION

We conclude that P. acnes is an opportunistic pathogen with a likely underestimated role in the development of various human diseases associated with significant morbidity and, in some cases, mortality. As such, these findings offer the potential for new studies aimed at understanding the pathological mechanisms driving the observed disease associations, as well as novel diagnostic strategies and treatment strategies, particularly for degenerative disc disease. These slides can be retrieved under Electronic Supplementary Material.

A case-control study of lower urinary-tract infections, associated antibiotics and the risk of developing prostate cancer using PCBaSe 3.0

Objectives

To investigate the association between lower urinary-tract infections, their associated antibiotics and the subsequent risk of developing PCa.

Subjects/Patients (or materials) and methods

Using data from the Swedish PCBaSe 3.0, we performed a matched case-control study (8762 cases and 43806 controls). Conditional logistic regression analysis was used to assess the association between lower urinary-tract infections, related antibiotics and PCa, whilst adjusting for civil status, education, Charlson Comorbidity Index and time between lower urinary-tract infection and PCa diagnosis.

Results

It was found that lower urinary-tract infections did not affect PCa risk, however, having a lower urinary-tract infection or a first antibiotic prescription 6–12 months before PCa were both associated with an increased risk of PCa (OR: 1.50, 95% CI: 1.23–1.82 and 1.96, 1.71–2.25, respectively), as compared to men without lower urinary-tract infections. Compared to men with no prescriptions for antibiotics, men who were prescribed ≥10 antibiotics, were 15% less likely to develop PCa (OR: 0.85, 95% CI: 0.78–0.91).

Conclusion

PCa was not found to be associated with diagnosis of a urinary-tract infection or frequency, but was positively associated with short time since diagnoses of lower urinary-tract infection or receiving prescriptions for antibiotics. These observations can likely be explained by detection bias, which highlights the importance of data on the diagnostic work-up when studying potential risk factors for PCa.

Platelet activation and aggregation by the opportunistic pathogen Cutibacterium (Propionibacterium) acnes

Cutibacterium (Propionibacterium) acnes, considered a part of the skin microbiota, is one of the most commonly isolated anaerobic bacteria from medical implants in contact with plasma. However, the precise interaction of C. acnes with blood cells and plasma proteins has not been fully elucidated. Herein, we have investigated the molecular interaction of C. acnes with platelets and plasma proteins. We report that the ability of C. acnes to aggregate platelets is dependent on phylotype, with a significantly lower ability amongst type IB isolates, and the interaction of specific donor-dependent plasma proteins (or concentrations thereof) with C. acnes. Pretreatment of C. acnes with plasma reduces the lag time before aggregation demonstrating that pre-deposition of plasma proteins on C. acnes is an important step in platelet aggregation. Using mass spectrometry we identified several plasma proteins deposited on C. acnes, including IgG, fibrinogen and complement factors. Inhibition of IgG, fibrinogen or complement decreased C. acnes-mediated platelet aggregation, demonstrating the importance of these plasma proteins for aggregation. The interaction of C. acnes and platelets was visualized using fluorescence microscopy, verifying the presence of IgG and fibrinogen as components of the aggregates, and co-localization of C. acnes and platelets in the aggregates. Here, we have demonstrated the ability of C. acnes to activate and aggregate platelets in a bacterium and donor-specific fashion, as well as added mechanistic insights into this interaction.

Acne in late adolescence and risk of prostate cancer

Accumulating evidence suggest that Propionibacterium acnes may play a role in prostate carcinogenesis, but data are so far limited and inconclusive. The aim of this population-based cohort study was therefore to test whether presence of acne vulgaris during late adolescence is associated with an increased risk of prostate cancer later in life. We identified a large cohort of young men born in Sweden between 1952 and 1956, who underwent mandatory assessment for military conscription around the age of 18 (n = 243,187). Test information along with health data including medical diagnoses at time of conscription was available through the Swedish Military Conscription Register and the National Patient Register. The cohort was followed through linkages to the Swedish Cancer Register to identify the occurrence of prostate cancer until December 31, 2009. We used Cox regression to calculate adjusted hazard ratios (HR) and 95% confidence intervals (95% CI) for the association between acne in adolescence and prostate cancer risk. A total of 1,633 men were diagnosed with prostate cancer during a median follow-up of 36.7 years. A diagnosis of acne was associated with a statistically significant increased risk for prostate cancer (adjusted HR: 1.43 95%; CI: 1.06-1.92), particularly for advanced stage disease (HR: 2.37 95%; CI 1.19-4.73). A diagnosis of acne classified as severe conferred a sixfold increased risk of prostate cancer (HR: 5.70 95% CI 1.42-22.85). Data from this large prospective population-based cohort add new evidence supporting a role of P. acnes infection in prostate cancer.

Self-reported acne is not associated with prostate cancer

OBJECTIVE

Some studies have suggested an inverse association between acne vulgaris and the acne-related bacterium Propionibacterium acnes and prostate cancer (PCa). Self-reported acne might be an easily obtainable marker to identify men at relatively low risk of PCa and might be incorporated into PCa risk calculators. This study aimed to evaluate the association between self-reported acne and PCa in a large case-referent study.

METHODS AND MATERIALS

The case group comprised 942 patients with PCa recruited from a population-based cancer registry in 2003 to 2006, 647 of whom met the criteria for aggressive PCa. The referents (n = 2,062) were a random sample of the male general population. All subjects completed a questionnaire on risk factors for cancer, including questions about acne. Odds ratios (ORs) and 95% confidence interval (CI) were calculated using multivariable logistic regression for PCa and aggressive PCa as separate end points, while adjusting for age and family history of PCa.

RESULTS

A history of acne was reported by 320 cases (33.9%) and 739 referents (35.8%). Self-reported acne was significantly associated neither with PCa (adjusted OR = 0.95, 95% CI: 0.80-1.12) nor with aggressive PCa (adjusted OR = 0.97, 95% CI: 0.80-1.18).

CONCLUSION

Self-reported acne is not suitable as a marker to identify men at low risk of aggressive PCa.

Infections and inflammation in prostate cancer

The frequent observation of both acute and chronic inflammation of unknown stimulus in the adult prostate has motivated a large body of research aimed at identifying potential infectious agents that may elicit prostatic inflammation. The overarching hypothesis is that infection-induced inflammation may be associated with prostate cancer development or progression, as inflammation is known to serve as an "enabling characteristic" of cancer. With recent advances in molecular techniques for microorganism identification, a panoply of microorganisms has been scrutinized in prostate tissues and in relation to prostate carcinogenesis. The aim of this review is to summarize the current literature on the evidence for infectious agents as a contributing factor to prostatic inflammation and prostate cancer, and to highlight recent literature suggesting an infectious etiology to the biogenesis of prostatic corpora amylacea and on the development of mouse models of prostatic infections.

A mouse model of chronic prostatic inflammation using a human prostate cancer-derived isolate of Propionibacterium acnes

BACKGROUND

Prostatic inflammation has been linked to a number of prostatic diseases such as benign prostatic hyperplasia (BPH), prostatitis syndromes, and prostate cancer. Major unanswered questions include what pathogenic mechanisms, such as bacterial infections, may drive the accumulation of inflammatory infiltrates in the human prostate, and how inflammation might contribute to disease. To study this potential link in an in vivo system, we developed a mouse model of long-term bacteria-induced chronic inflammation of the prostate using a human prostatectomy-derived strain of Propionibacterium acnes.

METHODS

C57BL/6J mice were inoculated, via urethral catheterization, with vehicle control or a prostatectomy-derived strain of P. acnes (PA2). Animals were assessed at 2 days, 1, 2, or 8 weeks post-inoculation via histology and immunohistochemistry (IHC).

RESULTS

PA2 inoculation resulted in severe acute and chronic inflammation confined to the dorsal lobe of the prostate. Chronic inflammation persisted for at least 8 weeks post-inoculation. Inflammatory lesions were associated with an increase in the Ki-67 proliferative index, and diminished Nkx3.1 and androgen receptor (AR) production. Interestingly, the observed response required live bacteria and both IHC and in situ hybridization assays for P. acnes indicated a potential intracellular presence of P. acnes in prostate epithelial cells.

CONCLUSIONS

To our knowledge, this is the first mouse model of long-term prostatic inflammation induced by P. acnes, and more generally, any prostatectomy-derived bacterial isolate. This model may serve as a valuable preclinical model of chronic prostatic inflammation that can be used to mechanistically study the link between inflammation and prostatic disease.

Multilocus sequence typing (MLST) analysis of Propionibacterium acnes isolates from radical prostatectomy specimens

BACKGROUND

Inflammation is commonly observed in radical prostatectomy specimens, and evidence suggests that inflammation may contribute to prostate carcinogenesis. Multiple microorganisms have been implicated in serving as a stimulus for prostatic inflammation. The pro-inflammatory anaerobe, Propionibacterium acnes, is ubiquitously found on human skin and is associated with the skin disease acne vulgaris. Recent studies have shown that P. acnes can be detected in prostatectomy specimens by bacterial culture or by culture-independent molecular techniques.

METHODS

Radical prostatectomy tissue samples were obtained from 30 prostate cancer patients and subject to both aerobic and anaerobic culture. Cultured species were identified by 16S rDNA gene sequencing. Propionibacterium acnes isolates were typed using multilocus sequence typing (MLST).

RESULTS

Our study confirmed that P. acnes can be readily cultured from prostatectomy tissues (7 of 30 cases, 23%). In some cases, multiple isolates of P. acnes were cultured as well as other Propionibacterium species, such as P. granulosum and P. avidum. Overall, 9 of 30 cases (30%) were positive for Propionibacterium spp. MLST analyses identified eight different sequence types (STs) among prostate-derived P. acnes isolates. These STs belong to two clonal complexes, namely CC36 (type I-2) and CC53/60 (type II), or are CC53/60-related singletons.

CONCLUSIONS

MLST typing results indicated that prostate-derived P. acnes isolates do not fall within the typical skin/acne STs, but rather are characteristic of STs associated with opportunistic infections and/or urethral flora. The MLST typing results argue against the likelihood that prostatectomy-derived P. acnes isolates represent contamination from skin flora.

Prostate cancer and inflammation: the evidence

Chronic inflammation is now known to contribute to several forms of human cancer, with an estimated 20% of adult cancers attributable to chronic inflammatory conditions caused by infectious agents, chronic non-infectious inflammatory diseases and/or other environmental factors. Indeed, chronic inflammation is now regarded as an 'enabling characteristic' of human cancer. The aim of this review is to summarize the current literature on the evidence for a role for chronic inflammation in prostate cancer aetiology, with a specific focus on recent advances regarding the following: (i) potential stimuli for prostatic inflammation; (ii) prostate cancer immunobiology; (iii) inflammatory pathways and cytokines in prostate cancer risk and development; (iv) proliferative inflammatory atrophy (PIA) as a risk factor lesion to prostate cancer development; and (v) the role of nutritional or other anti-inflammatory compounds in reducing prostate cancer risk.

Thirty years of research on infection and prostate cancer: no conclusive evidence for a link. A systematic review

BACKGROUND

The potential role of genitourinary infection in the etiology of prostate cancer (CaP) has been extensively investigated for 30 years. Two basic approaches have been used: tissue-based methods (polymerase chain reaction, immunohistochemistry, and in situ hybridization) and serologic assays (enzyme-linked immunosorbent assay, immunofluorescence, etc.). The objective of this review was to answer the question of whether infection of the male genitourinary tract may have a role in the etiology of CaP.

MATERIALS AND METHODS

We have carried out a systematic review of the evidence that was published in the MEDLINE/PubMed database until December 2011. The search terms included "prostate cancer," "infection," and the explicit names of the various infectious agents. Additional studies were identified using a reference search. A total of 74 papers were included in the review, which cover the following infectious agents: human papillomavirus, cytomegalovirus, herpes simplex virus, Epstein-Barr virus, human herpesvirus, BK virus, JC virus, chlamydia, mycoplasma, ureaplasma, trichomonas, neisseria, treponema, Propionibacterium acnes, xenotropic murine leukemia virus-related virus and Candida albicans.

RESULTS

Despite the variable study designs and methodological approaches that were used, most of the pathogens that were studied were unlikely to be directly involved in prostate carcinogenesis.

CONCLUSIONS

The role of infection in the etiology of CaP has yet to be determined despite 30 years of research efforts. A discovery of an infectious agent that is associated with CaP would be of great medical importance; however, such a link would have to be firmly established before impacting on patient care.