CD4+ lymphocytes modulate prostate cancer progression in mice

The role of proinflammatory cytokines and CXC chemokines (CXCL1-CXCL16) in the progression of prostate cancer: insights on their therapeutic management

Reproductive cancers are malignancies that develop in the reproductive organs. One of the leading cancers affecting the male reproductive system on a global scale is prostate cancer (PCa). The negative consequences of PCa metastases endure and are severe, significantly affecting mortality and life quality for those who are affected. The association between inflammation and PCa has captured interest for a while. Inflammatory cells, cytokines, CXC chemokines, signaling pathways, and other elements make up the tumor microenvironment (TME), which is characterized by inflammation. Inflammatory cytokines and CXC chemokines are especially crucial for PCa development and prognosis. Cytokines (interleukins) and CXC chemokines such as IL-1, IL-6, IL-7, IL-17, TGF-β, TNF-α, CXCL1-CXCL6, and CXCL8-CXCL16 are thought to be responsible for the pleiotropic effects of PCa, which include inflammation, progression, angiogenesis, leukocyte infiltration in advanced PCa, and therapeutic resistance. The inflammatory cytokine and CXC chemokines systems are also promising candidates for PCa suppression and immunotherapy. Therefore, the purpose of this work is to provide insight on how the spectra of inflammatory cytokines and CXC chemokines evolve as PCa develops and spreads. We also discussed recent developments in our awareness of the diverse molecular signaling pathways of these circulating cytokines and CXC chemokines, as well as their associated receptors, which may one day serve as PCa-targeted therapies. Moreover, the current status and potential of theranostic PCa therapies based on cytokines, CXC chemokines, and CXC receptors (CXCRs) are examined.

YTE-17 inhibits colonic carcinogenesis by resetting antitumor immune response via Wnt5a/JNK mediated metabolic signaling

The density and composition of lymphocytes infiltrating colon tumors serve as predictive factors for the clinical outcome of colon cancer. Our previous studies highlighted the potent anti-cancer properties of the principal compounds found in Garcinia yunnanensis (YTE-17), attributing these effects to the regulation of multiple signaling pathways. However, knowledge regarding the mechanism and effect of YTE-17 in the prevention of colorectal cancer is limited. In this study, we conducted isobaric tags for relative and absolute quantification (iTRAQ) analysis on intestinal epithelial cells (IECs) exposed YTE-17, both in vitro and invivo, revealing a significant inhibition of the Wnt family member 5a (Wnt5a)/c-Jun N-terminal kinase (JNK) signaling pathway. Subsequently, we elucidated the influence and mechanism of YTE-17 on the tumor microenvironment (TME), specifically focusing on macrophage-mediated T helper 17 (Th17) cell induction in a colitis-associated cancer (CAC) model with Wnt5a deletion. Additionally, we performed the single-cell RNA sequencing (scRNA-seq) on the colonic tissue from the Wnt5a-deleted CAC model to characterize the composition, lineage, and functional status of immune mesenchymal cells during different stages of colorectal cancer (CRC) progression. Remarkably, our findings demonstrate a significant reduction in M2 macrophage polarization and Th17 cell phenotype upon treatment with YTE-17, leading to the restoration of regulatory T (Treg)/Th17 cell balance in azoxymethane (AOM)/dextran sodium sulfate (DSS) model. Furthermore, we also confirmed that YTE-17 effectively inhibited the glycolysis of Th17 cells in both direct and indirect co-culture systems with M2 macrophages. Notably, our study shed light on potential mechanisms linking the non-canonical Wnt5a/JNK signaling pathway and well-established canonical β-catenin oncogenic pathway in vivo. Specifically, we proposed that Wnt5a/JNK signaling activity in IECs promotes the development of cancer stem cells with β-catenin activity within the TME, involving macrophages and T cells. In summary, our study undergoes the potential of YTE-17 as a preventive strategy against CRC development by addressing the imbalance with the immune microenvironment, thereby mitigating the risk of malignancies.

Health inequity drives disease biology to create disparities in prostate cancer outcomes

Prostate cancer exerts a greater toll on African American men than on White men of European descent (hereafter referred to as European American men): the disparity in incidence and mortality is greater than that of any other common cancer. The disproportionate impact of prostate cancer on Black men has been attributed to the genetics of African ancestry, to diet and lifestyle risk factors, and to unequal access to quality health care. In this Review, all of these influences are considered in the context of the evolving understanding that chronic or recurrent inflammatory processes drive prostatic carcinogenesis. Studies of inherited susceptibility highlight the contributions of genes involved in prostate cell and tissue repair (BRCA1/2, ATM) and regeneration (HOXB13 and MYC). Social determinants of health appear to accentuate these genetic influences by fueling prostate inflammation and associated cell and genome damage. Molecular characterization of the prostate cancers that arise in Black versus White men further implicates this inflammatory microenvironment in disease behavior. Yet, when Black and White men with similar grade and stage of prostate cancer are treated equally, they exhibit equivalent outcomes. The central role of prostate inflammation in prostate cancer development and progression augments the impact of the social determinants of health on disease pathogenesis. And, when coupled with poorer access to high-quality treatment, these inequities result in a disparate burden of prostate cancer on African American men.

Immunohistochemical investigation of cytokine expression levels as biomarkers in transrectal ultrasound-guided needle biopsy specimens of prostate adenocarcinoma

Cytokines influence the biological behaviour of prostate cancer (PC) and may influence patient outcome and serve as useful prognostic biomarkers. The aim of the present study was to evaluate cytokine expression levels in prostatic needle biopsy specimens and the association with clinicopathological characteristics of patients with PC. A total of 18 patients with PC who underwent transrectal ultrasound (TRUS) guided prostate biopsy were included in the clinical study. These patients were naïve to radiotherapy (RT) or androgen deprivation therapy prior to TRUS biopsy and clinical follow up data was collected. Cytokine expression levels were analysed by using immunohistochemistry and Spearman's correlation test was used to determine the correlation between cytokine expression and clinicopathological characteristics. Expression levels of pro-inflammatory TNF-α and IL-6 decreased as Gleason score (GS) increased; however, a statistically significant difference was not detected. A statically significant correlation was observed between needle biopsy specimen and pre-RT plasma sample expression levels of pro-inflammatory TNF-α and IL-6 (P=0.01 and P=0.05, respectively) and anti-inflammatory TGF-β1 (P=0.05). However, further studies are needed to confirm these results using a larger sample size to confirm the prognostic value of pro-inflammatory TNF-α and IL-6 and anti-inflammatory TGF-β1 in patients with PC.

Diagnosis of chronic prostatitis by noninvasive methods in elderly patients with benign prostatic hyperplasia in China

Chronic prostatitis is hard to be identified in BPH patients in clinical works. This study aimed to diagnose chronic prostatitis in BPH patients by noninvasive methods. BPH patients who received transurethral resection of prostate from January 2014 to July 2015 were enrolled in current study. Patients were received examinations of PSA, sex hormones, inflammatory cytokines, metabolic panel and transrectal ultrasonography. According to histological results, patients were divided into two group of BPH with/without prostatitis. Logistic regression was used to find risk factors of chronic prostatitis. As a result, 181 men with an average age of 72.15 ± 8.41 years were enrolled in this study, including 116 patients with prostatitis and 65 patients without prostatitis. The storage sub-score, PSA and IL-2R were significantly higher in patients with prostatitis than those without prostatitis. Based on logistic regression analysis, the above three parameters were also the risk factors of BPH with prostatitis. The diagnostic model was calculated as: 0.317 × storage sub-score + 0.092 × PSA + 0.003 × IL-2R - 4.296. The AUC was 0.725. Histological prostatitis in BPH patients can be diagnosed by the combination of serum IL-2R, PSA and storage sub-score. Identification of chronic prostatitis in BPH patients could more efficiently alleviate urinary symptoms and reduce the risk of disease progression.

YYFZBJS ameliorates colorectal cancer progression in ApcMin/+ mice by remodeling gut microbiota and inhibiting regulatory T-cell generation

BACKGROUND

Progression of Colorectal cancer (CRC) is influenced by single or compounded environmental factors. Accumulating evidence shows that microbiota can influence the outcome of cancer immunotherapy. T cell, one of the main populations of effector immune cells in antitumor immunity, has been considered as a double-edged sword during the progression of CRC. Our previous studies indicate that traditional Chinese herbs (TCM) have potential anticancer effects in improving quality of life and therapeutic effect. However, little is known about the mechanism of TCM formula in cancer prevention.

METHODS

Here, we used C57BL/6 J Apc^Min/+ mice, an animal model of human intestinal tumorigenesis, to investigate the gut bacterial diversity and their mechanisms of action in gastrointestinal adenomas, and to evaluate the effects of Yi-Yi-Fu-Zi-Bai-Jiang-San (YYFZBJS) on of colon carcinogenesis in vivo and in vitro. Through human-into-mice fecal microbiota transplantation (FMT) experiments from YYFZBJS volunteers or control donors, we were able to differentially modulate the tumor microbiome and affect tumor growth as well as tumor immune infiltration.

RESULTS

We report herein, YYFZBJS treatment blocked tumor initiation and progression in Apc^Min/+ mice with less change of body weight and increased immune function. Moreover, diversity analysis of fecal samples demonstrated that YYFZBJS regulated animal's natural gut flora, including Bacteroides fragilis, Lachnospiraceae and so on. Intestinal tumors from conventional and germ-free mice fed with stool from YYFZBJS volunteers had been decreased. Some inflammation' expression also have been regulated by the gut microbiota mediated immune cells. Intestinal lymphatic, and mesenteric lymph nodes (MLN), accumulated CD4+ CD25+ Foxp3 positive Treg cells were reduced by YYFZBJS treatment in Apc^Min/+ mice. Although YYFZBJS had no inhibition on CRC cell proliferation by itself, the altered Tregs mediated by YYFZBJS repressed CRC cancer cell growth, along with reduction of the phosphorylation of β-catenin.

CONCLUSIONS

In conclusion, we demonstrated that gut microbiota and Treg were involved in CRC development and progression, and we propose YYFZBJS as a new potential drug option for the treatment of CRC. Video abstract.

Cytokines expression levels from tissue, plasma or serum as promising clinical biomarkers in adenocarcinoma of the prostate: a systematic review of recent findings

Prostate cancer (PC) is a common cancer (excluding non-melanoma skin cancer) in men in many parts of the world, although incidence and mortality rates vary significantly by population. In current medical practice, prognostic markers for PC include the presenting serum prostate-specific antigen (PSA) level, tumour Gleason score (GS) and clinical tumour stage. However, existing pre-treatment factors cannot be used to predict acute radiotherapy (RT)-induced toxicity. Therefore, new protein biomarkers are required in RT oncology to improve decision-making, treatment and therapy monitoring for PC patients. The aim of this systematic review is to the update potential research to address the difference in cytokine expression and their association with RT-induced toxicity and clinical outcomes. Studies were collected after searching three electronic databases: PubMed, Medline, and Google Scholar. An additional search was carried out through cross-check on a bibliography of selected articles. After the selection process made by two of the authors, 19 articles met the inclusion criteria and were included in the systematic review. Results from previous studies identified elevated levels of cytokines have been reported in several types of cancers and have sometimes correlated with disease progression or prognosis. Elevated levels of cytokine were noticed after immediate exposure to RT and their association with RT-induced acute/late toxicity of PC patients. Moreover, above studies also identified overexpression of cytokines on tumour biopsies and correlation with shortening cancer-specific survival and biochemical recurrence. Thus, altered levels of cytokine might be predictive biomarkers for RT-induced and clinical outcomes of PC patients.

Commensal bacteria modulate the tumor microenvironment

It has been recently shown that gut microbes modulate whole host immune and hormonal factors impacting the fate of distant preneoplastic lesions toward malignancy or regression. This raises the possibility that the tumor microenvironment interacts with broader systemic microbial-immune networks. These accumulated findings suggest novel therapeutic opportunities for holobiont engineering in emerging tumor microenvironments.

Gut bacteria require neutrophils to promote mammary tumorigenesis

Recent studies suggest that gastrointestinal tract microbiota modulate cancer development in distant non-intestinal tissues. Here we tested mechanistic hypotheses using a targeted pathogenic gut microbial infection animal model with a predilection to breast cancer. FVB-Tg(C3-1-TAg)cJeg/JegJ female mice were infected by gastric gavage with Helicobacter hepaticus at three-months-of-age putting them at increased risk for mammary tumor development. Tumorigenesis was multifocal and characterized by extensive infiltrates of myeloperoxidase-positive neutrophils otherwise implicated in cancer progression in humans and animal models. To test whether neutrophils were important in etiopathogenesis in this bacteria-triggered model system, we next systemically depleted mice of neutrophils using thrice weekly intraperitoneal injections with anti-Ly-6G antibody. We found that antibody depletion entirely inhibited tumor development in this H. hepaticus-infected model. These data demonstrate that host neutrophil-associated immune responses to intestinal tract microbes significantly impact cancer progression in distal tissues such as mammary glands, and identify gut microbes as novel targets for extra-intestinal cancer therapy.

Bisphenol A Disrupts HNF4α-Regulated Gene Networks Linking to Prostate Preneoplasia and Immune Disruption in Noble Rats

Exposure of humans to bisphenol A (BPA) is widespread and continuous. The effects of protracted exposure to BPA on the adult prostate have not been studied. We subjected Noble rats to 32 weeks of BPA (low or high dose) or 17β-estradiol (E2) in conjunction with T replenishment. T treatment alone or untreated groups were used as controls. Circulating T levels were maintained within the physiological range in all treatment groups, whereas the levels of free BPA were elevated in the groups treated with T+low BPA (1.06 ± 0.05 ng/mL, P < .05) and T+high BPA (10.37 ± 0.43 ng/mL, P < .01) when compared with those in both controls (0.1 ± 0.05 ng/mL). Prostatic hyperplasia, low-grade prostatic intraepithelial neoplasia (PIN), and marked infiltration of CD4+ and CD8+ T cells into the PIN epithelium (P < .05) were observed in the lateral prostates (LPs) of T+low/high BPA-treated rats. In contrast, only hyperplasia and high-grade PIN, but no aberrant immune responses, were found in the T+E2-treated LPs. Genome-wide transcriptome analysis in LPs identified differential changes between T+BPA vs T+E2 treatment. Expression of multiple genes in the regulatory network controlled by hepatocyte nuclear factor 4α was perturbed by the T+BPA but not by the T+E2 exposure. Collectively these findings suggest that the adult rat prostate, under a physiologically relevant T environment, is susceptible to BPA-induced transcriptomic reprogramming, immune disruption, and aberrant growth dysregulation in a manner distinct from those caused by E2. They are more relevant to our recent report of higher urinary levels BPA found in patients with prostate cancer than those with benign disease.

Impact of the immune system and immunotherapy in colorectal cancer

The development of cancer is a multi-step process involving the gradual loss of regulation over the growth and functional capabilities of normal cells. Much research has been focused on the numerous cell intrinsic factors that govern this process; however, recent attention has turned to understanding the cell extrinsic factors in the tumor microenvironment that appear equally critical to the progression and treatment of cancer. One critical component of the tumor microenvironment is the immune system and it has become increasingly evident that the immune system plays an integral role in preventing and promoting the development of cancer. Understanding the immune cell types and pathways involved in this process has enabled the development of novel biomarkers for prognosis and accelerated the development of immune-based therapeutics, both of which have the potential to forever change the treatment paradigms for colorectal cancer (CRC). In this review, we discuss the impact of the immune system on the initiation, progression and treatment of cancer, specifically focusing on CRC.

Cholera-toxin suppresses carcinogenesis in a mouse model of inflammation-driven sporadic colon cancer

Human studies and clues from animal models have provided important links between gastrointestinal (GI) tract bacteria and colon cancer. Gut microbiota antigenic stimuli play an important role in shaping the intestinal immune responses. Therefore, especially in the case of inflammation-associated colon cancer, gut bacteria antigens may affect tumorigenesis. The present study aimed to investigate the effects of the oral administration of a bacterial product with known immunomodulatory properties on inflammation-driven colorectal neoplasmatogenesis. For that, we used cholera-toxin and a well-established mouse model of colon cancer in which neoplasia is initiated by a single dose of the genotoxic agent azoxymethane (AOM) and subsequently promoted by inflammation caused by the colitogenic substance dextran sodium sulfate (DSS). We found that a single, low, non-pathogenic dose of CT, given orally at the beginning of each DSS treatment cycle downregulated neutrophils and upregulated regulatory T-cells and IL-10 in the colonic mucosa. The CT-induced disruption of the tumor-promoting character of DSS-induced inflammation led to the reduction of the AOM-initiated colonic polypoidogenesis. This result adds value to the emerging notion that certain GI tract bacteria or their products affect the immune system and render the microenvironment of preneoplastic lesions less favorable for promoting their evolution to cancer.

'Hygienic' lymphocytes convey increased cancer risk

Risk of developing inflammation-associated cancers has increased in industrialized countries during the past 30 years. One possible explanation is societal hygiene practices with use of antibiotics and Caesarian births that provide too few early life exposures of beneficial microbes. Building upon a 'hygiene hypothesis' model whereby prior microbial exposures lead to beneficial changes in CD4+ lymphocytes, here we use an adoptive cell transfer model and find that too few prior microbe exposures alternatively result in increased inflammation-associated cancer growth in susceptible recipient mice. Specifically, purified CD4+ lymphocytes collected from 'restricted flora' donors increases multiplicity and features of malignancy in intestinal polyps of recipient ApcMin/+ mice, coincident with increased inflammatory cell infiltrates and instability of the intestinal microbiota. We conclude that while a competent immune system serves to maintain intestinal homeostasis and good health, under hygienic rearing conditions CD4+ lymphocytes instead exacerbate inflammation-associated tumorigenesis, subsequently contributing to more frequent cancers in industrialized societies.

Gut microbiota and the paradox of cancer immunotherapy

It is recently shown that beneficial environmental microbes stimulate integrated immune and neuroendocrine factors throughout the body, consequently modulating regulatory T-lymphocyte phenotypes, maintaining systemic immune balance, and determining the fate of preneoplastic lesions toward regression while sustaining whole body good health. Stimulated by a gut microbiota-centric systemic homeostasis hypothesis, we set out to explore the influence of the gut microbiome to explain the paradoxical roles of regulatory T-lymphocytes in cancer development and growth. This paradigm shift places cancer prevention and treatment into a new broader context of holobiont engineering to cultivate a tumor-suppressive macroenvironment.

Urokinase-type plasminogen activator deficiency promotes neoplasmatogenesis in the colon of mice

Urokinase-type plasminogen activator (uPA) participates in cancer-related biologic processes, such as wound healing and inflammation. The present study aimed to investigate the effect of uPA deficiency on the long-term outcome of early life episodes of dextran sodium sulfate (DSS)-induced colitis in mice. Wild-type (WT) and uPA-deficient (uPA(-/-)) BALB/c mice were treated with DSS or remained untreated. Mice were necropsied either 1 week or 7 months after DSS treatment. Colon samples were analyzed by histopathology, immunohistochemistry, ELISA, and real-time polymerase chain reaction. At 7 months, with no colitis evident, half of the uPA(-/-) mice had large colonic polypoid adenomas, whereas WT mice did not. One week after DSS treatment, there were typical DSS-induced colitis lesions in both WT and uPA(-/-) mice. The affected colon of uPA(-/-) mice, however, had features of delayed ulcer re-epithelialization and dysplastic lesions of higher grade developing on the basis of a significantly altered mucosal inflammatory milieu. The later was characterized by more neutrophils and macrophages, less regulatory T cells (Treg), significantly upregulated cytokines, including interleukin-6 (IL-6), IL-17, tumor necrosis factor-α, and IL-10, and lower levels of active transforming growth factor-β1 (TGF-β1) compared to WT mice. Dysfunctional Treg, more robust protumorigenic inflammatory events, and an inherited inability to produce adequate amounts of extracellular active TGF-β1 due to uPA deficiency are interlinked as probable explanations for the inflammatory-induced neoplasmatogenesis in the colon of uPA(-/-) mice.

Pathogenic intestinal bacteria enhance prostate cancer development via systemic activation of immune cells in mice

A role for microbes has been suspected in prostate cancer but difficult to confirm in human patients. We show here that a gastrointestinal (GI) tract bacterial infection is sufficient to enhance prostate intraepithelial neoplasia (PIN) and microinvasive carcinoma in a mouse model. We found that animals with a genetic predilection for dysregulation of wnt signaling, Apc^Min/+ mutant mice, were significantly susceptible to prostate cancer in an inflammation-dependent manner following infection with Helicobacter hepaticus. Further, early neoplasia observed in infected Apc^Min/+ mice was transmissible to uninfected mice by intraperitoneal injection of mesenteric lymph node (MLN) cells alone from H. hepaticus-infected mutant mice. Transmissibility of neoplasia was preventable by prior neutralization of inflammation using anti-TNF-α antibody in infected MLN donor mice. Taken together, these data confirm that systemic inflammation triggered by GI tract bacteria plays a pivotal role in tumorigenesis of the prostate gland.

Animal models relevant to human prostate carcinogenesis underlining the critical implication of prostatic stem/progenitor cells

Recent development of animal models relevant to human prostate cancer (PC) etiopathogenesis has provided important information on the specific functions provided by key gene products altered during disease initiation and progression to locally invasive, metastatic and hormone-refractory stages. Especially, the characterization of transgenic mouse models has indicated that the inactivation of distinct tumor suppressor proteins such as phosphatase tensin homolog deleted on chromosome 10 (PTEN), Nkx3.1, p27(KIP1), p53 and retinoblastoma (pRb) may cooperate for the malignant transformation of prostatic stem/progenitor cells into PC stem/progenitor cells and tumor development and metastases. Moreover, the sustained activation of diverse oncogenic signaling elements, including epidermal growth factor receptor (EGFR), sonic hedgehog, Wnt/β-catenin, c-Myc, Akt and nuclear factor-kappaB (NF-κB) also may contribute to the acquisition of more aggressive and hormone-refractory phenotypes by PC stem/progenitor cells and their progenies during disease progression. Importantly, it has also been shown that an enrichment of PC stem/progenitor cells expressing stem cell-like markers may occur after androgen deprivation therapy and docetaxel treatment in the transgenic mouse models of PC suggesting the critical implication of these immature PC cells in treatment resistance, tumor re-growth and disease recurrence. Of clinical interest, the molecular targeting of distinct gene products altered in PC cells by using different dietary compounds has also been shown to counteract PC initiation and progression in animal models supporting their potential use as chemopreventive or chemotherapeutic agents for eradicating the total tumor cell mass, improving current anti-hormonal and chemotherapies and preventing disease relapse.

Treatment combining RU486 and Ad5IL-12 vector attenuates the growth of experimentally formed prostate tumors and induces changes in the sentinel lymph nodes of mice

BACKGROUND

Tumor immune responses are first generated and metastases often begin in tumor sentinel lymph nodes (TSLN). Therefore, it is important to promote tumor immunity within this microenvironment. Mifepristone (RU486) treatment can interfere with cortisol signaling that can lead to suppression of tumor immunity. Here, we assessed whether treatment with RU486 in conjunction with an intratumor injection of Ad5IL-12 vector (a recombinant adenovirus expressing IL-12) could impact the TSLN microenvironment and prostate cancer progression.

METHODS

The human PC3, LNCaP or murine TRAMP-C1 prostate cancer cell lines were used to generate subcutaneous tumors in NOD.scid and C57BL/6 mice, respectively. Adjuvant effects of RU486 were looked for in combination therapy with intratumor injections (IT) of Ad5IL-12 vector in comparison to PBS, DL70-3 vector, DL70-3 + RU486, RU486 and Ad5IL-12 vector treatment controls. Changes in tumor growth, cell cytotoxic activity and populations of CD4+/FoxP3+ T regulatory cells (Treg) in the TSLN were evaluated.

RESULTS

Treatment of human PC3 prostate xenograft or TRAMP-C1 tumors with combination Ad5IL-12 vector and RU486 produced significantly better therapeutic efficacy in comparison to controls. In addition, we found that combination therapy increased the capacity of TSLN lymphocytes to produce Granzyme B in response to tumor cell targets. Finally, combination therapy tended towards decreases of CD4+/FoxP3+ T regulatory cell populations to be found in the TSLN.

CONCLUSION

Inclusion of RU486 may serve as a useful adjuvant when combined with proinflammatory tumor killing agents by enhancement of the immune response and alteration of the TSLN microenvironment.

Cancer inflammation and regulatory T cells

Chronic inflammation is essential for cancer growth and metastasis. It follows that factors reducing inflammation would abrogate cancer and restore tissue health. However, roles for anti-inflammatory CD4+ regulatory cells (T(REG)) in cancer are enigmatic and controversial. Our recent data reveal that T(REG) may function in cancer similarly to inflammatory bowel disease or multiple sclerosis, whereby T(REG) accumulate but lack potency to restore tissue homeostasis under inflammatory conditions. Interestingly, early life exposures to diverse environmental organisms reinforce a protective T(REG) phenotype that inhibits cancer. In contrast, hygienic individuals with few exposures earlier in life suffer from a dysregulated T(REG) feedback loop. Consequently, hygienic subjects have increased risk of malignancy later in life. This cancer condition is reversible by blocking underlying inflammation. Taken together, these data help explain increased inflammation-associated cancer rates in hygienic societies and identify targets to abrogate cancer and restore overall health.

Unifying roles for regulatory T cells and inflammation in cancer

Activities of CD4(+) regulatory (T(REG)) cells restore immune homeostasis during chronic inflammatory disorders. Roles for T(REG) cells in inflammation-associated cancers, however, are paradoxical. It is widely believed that T(REG) function in cancer mainly to suppress protective anticancer responses. However, we demonstrate here that T(REG) cells also function to reduce cancer risk throughout the body by efficiently downregulating inflammation arising from the gastrointestinal (GI) tract. Building on a "hygiene hypothesis" model in which GI infections lead to changes in T(REG) that reduce immune-mediated diseases, here we show that gut bacteria-triggered T(REG) may function to inhibit cancer even in extraintestinal sites. Ability of bacteria-stimulated T(REG) to suppress cancer depends on interleukin (IL)-10, which serves to maintain immune homeostasis within bowel and support a protective antiinflammatory T(REG) phenotype. However, under proinflammatory conditions, T(REG) may fail to provide antiinflammatory protection and instead contribute to a T helper (Th)-17-driven procarcinogenic process; a cancer state that is reversible by downregulation of inflammation. Consequently, hygienic individuals with a weakened IL-10 and T(REG)-mediated inhibitory loop are highly susceptible to the carcinogenic consequences of elevated IL-6 and IL-17 and show more frequent inflammation-associated cancers. Taken together, these data unify seemingly divergent disease processes such as autoimmunity and cancer and help explain the paradox of T(REG) and inflammation in cancer. Enhancing protective T(REG) functions may promote healthful longevity and significantly reduce risk of cancer.

Roles for inflammation and regulatory T cells in colon cancer

Risk for developing cancer rises substantially as a result of poorly regulated inflammatory responses to pathogenic bacterial infections. Anti-inflammatory CD4(+) regulatory cells (T(REG)) function to restore immune homeostasis during chronic inflammatory disorders. It seems logical that T(REG) cells would function to reduce risk of inflammation-associated cancer in the bowel by down-regulating inflammation. It is widely believed, however, that T(REG) function in cancer mainly to suppress protective anticancer inflammatory responses. Thus roles for inflammation, T(REG) cells, and gut bacteria in cancer are paradoxical and are the subject of controversy. Our accumulated data build upon the "hygiene hypothesis" model in which gastrointestinal (GI) infections lead to changes in T(REG) that reduce inflammation-associated diseases. Ability of T(REG) to inhibit or suppress cancer depends upon gut bacteria and IL-10, which serve to maintain immune balance and a protective anti-inflammatory T(REG) phenotype. However, under poorly regulated pro-inflammatory conditions, T(REG) fail to inhibit and may instead contribute to a T helper (Th)-17-driven procarcinogenic process, a cancer state that is reversible by down-regulation of inflammation and interleukin (IL)-6. Consequently, hygienic individuals with a weakened IL-10- and T(REG)-mediated inhibitory loop are highly susceptible to the carcinogenic consequences of elevated inflammation and show more frequent inflammation-associated cancers. Taken together, these data help explain the paradox of inflammation and T(REG) in cancer and indicate that targeted stimulation of T(REG) may promote health and significantly reduce risk of cancer.

Polyps wrap mast cells and Treg within tumorigenic tentacles

Gounaris and colleagues describe a previously unrecognized cross-talk between mast cells and Treg in colon adenomatous polyposis (Gounaris et al., Cancer Res 2009;69:5490-7). Adoptively transferred Treg suppress the focal mastocytosis that fosters tumor initiation and progression. In contrast, endogenous Treg, which abundantly infiltrate polyps, show proinflammatory activity under unknown microenvironmental cues that promote mast cell differentiation and expansion. Compartmentalized Treg plasticity seems to be a key factor in establishing the optimal milieu for cancer development in the intestines. Treg partnership with mast cells recapitulates the complexity of innate-adaptive networks characterizing gut inflammation and represents a novel target for cancer immunotherapy.