The lung microbiota: role in maintaining pulmonary immune homeostasis and its implications in cancer development and therapy.

Like other body districts, lungs present a complex bacteria community. An emerging function of lung microbiota is to promote and maintain a state of immune tolerance, to prevent uncontrolled and not desirable inflammatory response caused by inhalation of harmless environmental stimuli. This effect is mediated by a continuous dialog between commensal bacteria and immune cells resident in lungs, which express a repertoire of sensors able to detect microorganisms. The same receptors are also involved in the recognition of pathogens and in mounting a proper immune response. Due to its important role in preserving lung homeostasis, the lung microbiota can be also considered a mirror of lung health status. Indeed, several studies indicate that lung bacterial composition drastically changes during the occurrence of pulmonary pathologies, such as lung cancer, and the available data suggest that the modifications of lung microbiota can be part of the etiology of tumors in lungs and can influence their progression and response to therapy. These results provide the scientific rationale to analyze lung microbiota composition as biomarker for lung cancer and to consider lung microbiota a new potential target for therapeutic intervention to reprogram the antitumor immune microenvironment. In the present review, we discussed about the role of lung microbiota in lung physiology and summarized the most relevant data about the relationship between lung microbiota and cancer.

TLR3 Expression Induces Apoptosis in Human Non-Small-Cell Lung Cancer.

The prognostic value of Toll-like receptor 3 (TLR3) is debated in cancer, differing between tumor types, methods, and cell types. We recently showed for the first time that TLR3 expression on early stage non-small-cell lung cancer (NSCLC) results associated with a good prognosis. Here, we provide experimental evidences explaining the molecular reason behind TLR3's favorable prognostic role. We demonstrated that TLR3 activation in vitro induces apoptosis in lung cancer cell lines and, accordingly, that TLR3 expression is associated with caspase-3 activation in adenocarcinoma NSCLC specimens, both evaluated by immunohistochemistry. Moreover, we showed that TLR3 expression on cancer cells contributes to activate the CD103+ lung dendritic cell subset, that is specifically associated with processing of antigens derived from apoptotic cells and their presentation to CD8+ T lymphocytes. These findings point to the relevant role of TLR3 expression on lung cancer cells and support the use of TLR3 agonists in NSCLC patients to re-activate local innate immune response.

Activation of NK cell cytotoxicity by aerosolized CpG-ODN/poly(I:C) against lung melanoma metastases is mediated by alveolar macrophages.

Controversies remain about NK cells direct responsiveness to Toll-like receptor (TLR) agonists or dependence on macrophages. In a melanoma lung metastasis model, aerosolized TLR9 and TLR3 agonists have been reported to induce antitumor immunity through NK cells activation. In the current study, we demonstrated that in vitro TLR9/TLR3 stimulation induced IFN-γ secretion by NK cells, but an increase in their cytotoxicity was detected only after NK cells co-culture with in vitro TLR9/TLR3 agonists pretreated alveolar macrophages. Alveolar macrophages from melanoma lung metastases-bearing mice, treated with aerosolized TLR agonists, also promoted NK cell cytotoxicity. Activated NK cells from lungs of melanoma metastases-bearing mice that were given aerosolized TLR9/TLR3 agonists were able to polarize naive alveolar macrophages toward a M1-like phenotype. Our results demonstrate that activation of NK cells in the lung after TLR engagement is mediated by alveolar macrophages and that activated NK cells shape macrophage behavior.

CpG-oligodeoxynucleotides exert remarkable antitumor activity against diffuse malignant peritoneal mesothelioma orthotopic xenografts.

BACKGROUND: Diffuse malignant peritoneal mesothelioma (DMPM) is a rare and locally aggressive disease. DMPM prognosis is dismal, mainly due to the lack of effective treatment options and the development of new therapeutic strategies is urgently needed. In this context, novel immunotherapy approaches can be explored in an attempt to improve DMPM patients' survival. METHODS: We tested the efficacy of CpG-oligodeoxynucleotides (CpG-ODN), synthetic DNA sequences recognized by Toll-like receptor 9 and able to induce innate/adaptive immune response, in two DMPM orthotopic xenografts (MesoII and STO), which properly recapitulate the dissemination pattern of the disease in the peritoneal cavity. Severe combined immunodeficiency mice carrying DMPM xenografts were treated at different stages of tumor development with i.p. delivered CpG-ODN1826 for 4 weeks. CpG-ODN1826-induced modulation in the composition of peritoneal immune infiltrate was assessed by flow cytometry. RESULTS: When administered to early-stage tumors (i.e., 4 days after i.p. DMPM cell injection in mice), the agent exhibited impressive efficacy against MesoII by completely inhibiting tumor take and ascites development (no evidence of tumor masses and ascites in 6/6 mice at necropsy), and also impaired STO tumor take and growth (4/6 tumor-free mice; i.p. tumor masses reduced by 94 % in the 2 remaining mice, P = 0.00005). Interestingly, when tested against late-stage STO tumors (i.e., 11 days after i.p. DMPM cell injection in mice), CpG-ODN1826 was still able to reduce the growth of i.p. tumor masses by 66 % (P = 0.0009). Peritoneal washings of tumor-bearing mice revealed a strong increase of macrophage infiltration together with a decrease in the presence of B-1 cells and a reduced IgM concentration after CpG-ODN1826 treatment. CONCLUSIONS: Our results indicate that locally administered CpG-ODN1826 is able to markedly affect the growth of both early- and late-stage DMPM orthotopic xenografts in the absence of severe side effects, and suggest a possible clinical role for the agent in the therapy of DMPM.

Sodium glucose cotransporter 1 ligand BLF501 as a novel tool for management of gastrointestinal mucositis.

BACKGROUND: Recent studies demonstrated that engagement of sodium glucose transporter 1 (SGLT-1) by orally administered D-glucose protects the intestinal mucosa from lipopolysaccharide (LPS)-induced injury. We tested whether SGLT-1 engagement might protect the intestinal mucosa from doxorubicin (DXR)- and 5-fluorouracil (5-FU)-induced injury in animal models mimicking acute or chronic mucositis. METHODS: Mice were treated intraperitoneally with DXR, alone or in combination with 5-FU, and orally with BLF501, a glucose-derived synthetic compound with high affinity for SGLT-1. Intestinal mucosal epithelium integrity was assessed by histological analysis, cellular proliferation assays, real-time PCR gene expression assays and Western blot assays. Student's t-test (paired two-tailed) and χ2 analyses were used for comparisons between groups. Differences were considered significant at p < 0.05. RESULTS: BLF501 administration in mice treated with DXR and/or 5-FU decreased the injuries to the mucosa in terms of epithelial integrity and cellular proliferative ability. Co-treatment with BLF501 led to a normal expression and distribution of both zonula occludens-1 (ZO-1) and beta-catenin, which were underexpressed after treatment with either chemotherapeutic agent alone. BLF501 administration also restored normal expression of caspase-3 and ezrin/radixin/moesin (ERM), which were overexpressed after treatment with DXR and 5-FU. In SGLT1-/- mice, BLF501 had no detectable effects. BLF501 administration in wild-type mice with growing A431 tumors did not modify antitumor activity of DXR. CONCLUSIONS: BLF501-induced protection of the intestinal mucosa is a promising novel therapeutic approach to reducing the severity of chemotherapy-induced mucositis.

Maspin influences response to doxorubicin by changing the tumor microenvironment organization.

Altered degradation and deposition of extracellular matrix are hallmarks of tumor progression and response to therapy. From a microarray supervised analysis on a dataset of chemotherapy-treated breast carcinoma patients, maspin, a member of the serpin protease inhibitor family, has been the foremost variable identified in non-responsive versus responsive tumors. Accordingly, in a series of 52 human breast carcinomas, we detected high maspin expression in tumors that progressed under doxorubicin (DXR)-based chemotherapy. Our analysis of the role of maspin in response to chemotherapy in human MCF7 and MDAMB231 breast and SKOV3 ovarian carcinoma cells transfected to overexpress maspin and injected into mice showed that maspin overexpression led to DXR resistance through the maspin-induced collagen-enriched microenvironment and that an anti-maspin neutralizing monoclonal antibody reversed the collagen-dependent DXR resistance. Impaired diffusion and decreased DXR activity were also found in tumors derived from Matrigel-embedded cells, where abundant collagen fibers characterize the tumor matrix. Conversely, liposome-based DXR reached maspin-overexpressing tumor cells despite the abundant extracellular matrix and was more efficient in reducing tumor growth. Our results identify maspin-induced accumulation of collagen fibers as a cause of disease progression under DXR chemotherapy for breast cancer. Use of a more hydrophilic DXR formulation or of a maspin inhibitor in combination with chemotherapy holds the promise of more consistent responses to maspin-overexpressing tumors and dense-matrix tumors in general.

FOXP3 expression in tumor cells and implications for cancer progression.

FOXP3 is a member of the forkhead/winged-helix family of transcriptional regulators. Defects in the FOXP3 gene cause an X-linked autoimmune/immunodeficiency syndrome in humans and the Scurfy phenotype in mice. FOXP3 acts mainly in regulating the development and function of CD4+CD25+ regulatory T cells. Although initially thought to be specific for these cells, FOXP3 expression has recently been described in non-hematopoietic cells, including epithelial cells of multiple lineages and of different tissue origins. Moreover, FOXP3 expression has been detected in tumor cells of both epithelial and non-epithelial tissues. The role of FOXP3 expression by tumor cells remains controversial, with in vitro studies pointing to an onco-suppressive action, whereas studies conducted on human samples associate FOXP3 expression by tumor cells with metastatic spread. Here, we review evidence for the multi-faceted role of FOXP3 in cancer cells.

Influence of fatty acid-free diet on mammary tumor development and growth rate in HER-2/Neu transgenic mice.

Numerous investigations have found a relationship between higher risk of cancer and increased intake of fats, while results of clinical studies of fat reduction and breast cancer recurrence have been mixed. A diet completely free of fats cannot be easily administered to humans, but experimental studies in mice can be done to determine whether this extreme condition influences tumor development. Here, we examined the effects of a FA-free diet on mammary tumor development and growth rate in female FVB-neu proto-oncogene transgenic mice that develop spontaneous multifocal mammary tumors after a long latency period. Mice were fed a fatty acid-free diet beginning at 112, 35, and 30 days of age. In all these experiments, tumor appearance was delayed, tumor incidence was reduced and the mean number of palpable mammary tumors per mouse was lower, as compared to standard diet-fed mice. By contrast, tumor growth rate was unaffected in mice fed the fatty acid-free diet. Plasma of mice fed the fatty acid-free diet revealed significantly higher contents of oleic, palmitoleic and 20:3ω9 acids and lower contents of linoleic and palmitic acids. In conclusion, these findings indicate that a FA-free diet reduces tumor incidence and latency but not tumor growth rate, suggesting that a reduction in dietary FAs in humans may have a protective effect on tumorigenesis but not on tumors once they appear.

EGFR through STAT3 modulates ΔN63α expression to sustain tumor-initiating cell proliferation in squamous cell carcinomas.

Many squamous cell carcinomas (SCCs) are characterized by high levels of EGFR and by overexpression of the ΔNp63α isoform. Here, we investigated the regulation of ΔNp63α expression upon EGFR activation and the role of the EGFR-ΔNp63α axis in proliferation of SCC tumor-initiating cells (TICs). SCC cell lines A-431, Cal-27, and SCC-25 treated with EGF showed a time-dependent increase in ΔNp63α expression at the protein and mRNA levels, which was blocked by the tyrosine kinase inhibitor (TKI) Lapatinib. RNA interference experiments suggested the role of STAT3 in regulating ΔNp63α expression downstream of EGFR. Inactivation of EGFR by the monoclonal antibody Cetuximab and RNA interference against STAT3 or ΔNp63α impaired the TICs ability to grow under non-differentiating conditions. Radiation treatment, which triggers EGFR activation, induced ΔNp63α accumulation without affecting TICs proliferation, whereas the combination Cetuximab plus radiation significantly reduced TICs growth under non-differentiating conditions. Together, our findings provide evidence that ΔNp63α expression is regulated by EGFR activation through STAT3 and that the EGFR-ΔNp63α axis is crucial for proliferation of TICs present in SCCs.

Anti-tumor activity of CpG-ODN aerosol in mouse lung metastases.

Studies in preclinical models have demonstrated the superior anti-tumor effect of CpG oligodeoxynucleotides (CpG-ODN) when administered at the tumor site rather than systemically. We evaluated the effect of aerosolized CpG-ODN on lung metastases in mice injected with immunogenic N202.1A mammary carcinoma cells or weakly immunogenic B16 melanoma cells. Upon reaching the bronchoalveolar space, aerosolized CpG-ODN activated a local immune response, as indicated by production of IL-12p40, IFN-γ and IL-1ß and by recruitment and maturation of DC cells in bronchoalveolar lavage fluid of mice. Treatment with aerosolized CpG-ODN induced an expansion of CD4+ cells in lung and was more efficacious than systemic i.p. administration against experimental lung metastases of immunogenic N202.1A mammary carcinoma cells, whereas only i.p. delivery of CpG-ODN provided anti-tumor activity, which correlated with NK cell expansion in the lung, against lung metastases of the poorly immunogenic B16 melanoma. The inefficacy of aerosol therapy to induce NK expansion was related to the presence of immunosuppressive macrophages in B16 tumor-bearing lungs, as mice depleted of these cells by clodronate treatment responded to aerosol CpG-ODN through expansion of the NK cell population and significantly reduced numbers of lung metastases. Our results indicate that tumor immunogenicity and the tumor-induced immunosuppressive environment are critical factors to the success of CpG therapy in the lung, and point to the value of routine sampling of the lung immune environment in defining an optimal immunotherapeutic strategy.

High efficacy of CpG-ODN, cetuximab and cisplatin combination for very advanced ovarian xenograft tumors.

BACKGROUND: To mimic clinical treatment situations in advanced human ovarian disease, we tested the efficacy of CpG-oligodeoxynucleotides (CpG-ODN), synthetic DNA sequences recognized by Toll-like receptor 9 and able to induce innate/adaptive immune responses, in combination with other possible therapeutic reagents in ovarian carcinoma ascites-bearing athymic mice. METHODS: Mice injected i.p. with IGROV-1 ovarian cancer cells were treated at different stages of ascites progression for 4 weeks with CpG-ODN, alone or in combination with Bevacizumab, Polyinosinic:Polycytidylic acid (Poly(I):Poly(C)), Gefitinib, Cetuximab and Cisplatin. Median survival time (MST) was calculated for each group. IGROV-1 cells treated or not with Cetuximab were assayed for antibody-dependent cellular cytotoxicity by 51Cr-release assay, and for macrophage antibody-dependent cell-mediated phagocytosis by flow cytometry. RESULTS: In mice treated when ascitic fluid began to accumulate, CpG-ODN combined with Bevacizumab, Poly(I):Poly(C) or Gefitinib did not significantly increase MST as compared with that using CpG-ODN alone, whereas MST in mice treated with CpG-ODN plus Cetuximab was significantly increased (>103 days for combination vs 62 days for CpG alone; P = 0.0008), with 4/8 mice alive at the end of the experiment. In experiments in mice showing increased abdominal volume and body weight (27.9 ± 0.8 g after vs 23 ± 1.1 g before tumor cell injection), treatment with Cisplatin in addition to CpG-ODN/Cetuximab led to significantly increased MST (105.5 days; P = 0.001), with all mice still alive at 85 days, over that using CpG-ODN/Cetuximab (66 days), Cetuximab/Cisplatin (18.5 days), Cisplatin (23 days) or saline (16 days). At a very advanced stage of disease (body weight: 31.4 ± 0.9 g), when more than half of control mice had to be sacrificed 6 days after starting treatments, the triple-combination therapy still increased MST (45 days; P = 0.0089) vs controls. CONCLUSIONS: CpG-ODN combination therapies that enhance the immune response in the tumor microenvironment and concomitantly target tumor cells are highly efficacious even in experimental advanced malignancies. Although differences in the distribution of TLR9 in mice and humans and the enrichment of this receptor on innate immune cells of athymic mice must be considered, our results indicate a promising strategy to treat ovarian cancer patients with bulky ascites.

Induction of Paneth cell degranulation by orally administered Toll-like receptor ligands.

The secretory activity of Paneth cells is related to the bacterial milieu in the small intestine; however, the molecules involved in inducing Paneth cell secretion of enzymes and antimicrobial peptides are not well-defined. Mice treated orally with CpG-oligodeoxynucleotide (ODN), an agonist of Toll-like receptor (TLR) 9, showed rapid and massive Paneth cell degranulation. CpG-ODN-induced degranulation was not observed in TLR9(-/-) mice or in chimeric TLR9(-/-) mice reconstituted with wild-type (WT) bone marrow, but was observed in WT mice reconstituted with TLR9(-/-) bone marrow, indicating a role for TLR9-expressing gastrointestinal cells in CpG recognition. The TLR3 agonist polyinosinic-polycytidylic acid also induced rapid degranulation, whereas the TLR4 and TLR5 agonists LPS and flagellin, respectively, induced late degranulation mediated by TNF-α. Our evidence that TLR9 and TLR3 agonists induce Paneth cell degranulation points to the need for further studies of the mechanisms underlying Paneth cell function as an avenue toward preventing infection and treating inflammatory bowel diseases.

Surveillance of spontaneous breast cancer metastasis by TRAIL-expressing CD34⁺ cells in a xenograft model.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), delivered as a membrane-bound molecule expressed on the surface of adenovirus-transduced CD34(+) cells (CD34-TRAIL(+)), was analyzed for its apoptotic activity in vitro on 12 breast cancer cell lines representing estrogen receptor-positive, HER2(+) and triple-negative (TN) subtypes and for its effect on tumor growth, vascularization, necrosis, and lung metastasis incidence in NOD/SCID mice xenografted with the TN breast cancer line MDA-MB-231. Mesenchymal TN cell lines, which are the richest in putative tumor stem cells among the different breast cancer cell subtypes, were the most susceptible to apoptosis induced by CD34-TRAIL(+) cells. Indeed, tumor cell "stemness", assessed based on the proportion of CD44(+)/CD24(-/low) cells, was significantly correlated with susceptibility to TRAIL. Moreover, in vitro cytotoxicity experiments showed that CD34-TRAIL(+) cells selectively targeted CD44(+)/CD24(-/low) cells. Although in vivo treatment with CD34-TRAIL(+) cells did not lead to tumor growth inhibition, treated mice revealed significantly larger areas of necrosis associated with damage of tumor vasculature than did control mice. Moreover, lungs from MDA-MD-231 tumor-bearing mice were completely free of metastases at 12 days after the last injection of CD34-TRAIL(+) cells, whereas metastases were present in all control mouse lungs. An anti-metastatic effect of CD34-TRAIL(+) cells was also observed in a model of experimental lung metastases. The correlation between in vitro susceptibility to membrane-bound TRAIL and tumor stem cell content, together with CD34-TRAIL(+) cell-induced inhibition of the metastatic process, points to the selective targeting of cancer stem cells by CD34-armed cells and the potential value of such cells in eradicating tumor stem cells before the onset of overt metastases.

Stimulation of TLRs by LMW-HA induces self-defense mechanisms in vaginal epithelium.

The innate immune system is present throughout the female reproductive tract and functions in synchrony with the adaptive immune system to provide protection in a way that enhances the chances for fetal survival, while protecting against potential pathogens. Recent data show that activation of Toll-like receptor (TLR)2 and 4 by low-molecular weight hyaluronic acid (LMW-HA) in the epidermis induces secretion of the antimicrobial peptide ß-defensin 2. In the present work, we show that LMW-HA induces vaginal epithelial cells to release different antimicrobial peptides, via activation of TLR2 and TLR4. Further, we found that LMW-HA favors repair of vaginal epithelial injury, involving TLR2 and TLR4, and independently from its classical receptor CD44. This wound-healing activity of LMW-HA is dependent from an Akt/phosphatidylinositol 3 kinase pathway. Therefore, these findings suggest that the vaginal epithelium is more than a simple physical barrier to protect against invading pathogens: on the contrary, this surface acts as efficient player of innate host defense, which may modulate its antimicrobial properties and injury restitution activity, following LMW-HA stimulation; this activity may furnish an additional protective activity to this body compartment, highly and constantly exposed to microbiota, ameliorating the self-defense of the vaginal epithelium in both basal and pathological conditions.

Increased overall survival independent of RECIST response in metastatic breast cancer patients continuing trastuzumab treatment: evidence from a retrospective study.

Recent studies have reported the potential clinical utility for metastatic breast cancer (MBC) patients of continuing trastuzumab beyond progression. Based on those results, here the authors have examined the benefits of trastuzumab-continuation by specifically evaluating RECIST responses upon first line trastuzumab-treatment as a potential predictive marker for therapeutic effect of trastuzumab-continuation beyond metastatic disease progression. The authors carried out a retrospective analysis of 272 HER2 positive MBC patients under trastuzumab treatment at 22 different oncology Italian centers during the years of 2000 and 2001 who progressed under first line trastuzumab-treatment. The primary end point of the study was the survival from the date of first documented progression upon first line trastuzumab treatment of disease. Data analysis involved the use of matching on propensity score to balance variables between treated and untreated subjects and to reduce bias. Of the 272 HER2-positive MBC patients, 154 (56.6%) continued treatment. 79 (51.3%) of those 154 patients showed responses based on RECIST criteria during first-line trastuzumab-treatment. Of the 118 patients that suspended trastuzumab, RECIST responses had been observed in 44 (37.3%). Cox proportional hazards analysis of progressed patients, matched using propensity score, showed that discontinuation of trastuzumab at metastatic disease progression was a risk factor for significantly reduced overall survival in both responder (HR = 2.23; 95% CI = 1.03-4.82) and non-responder groups (HR = 3.53, 95% CI = 1.73-7.21), with no significant differences in the two estimated HRs (P-value of the likelihood-ratio test = 0.690). Continued trastuzumab treatment after disease progression has clinically and statistically significant effects in both RECIST responder and non-responder MBC patients.

Aerosol 1,25-dihydroxyvitamin D3 supplementation: A strategy to boost anti-tumor innate immune activity.

BACKGROUND: 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] plays a role in calcium homeostasis but can also exert immunomodulatory effects. In lungs, characterized by a particular immunosuppressive environment primarily due to the presence of alveolar macrophages (AM), 1,25(OH)2D3 has been shown to favor the immune response against pathogens. Here, we explored the ability of aerosolized 1,25(OH)2D3 to locally promote an anti-tumor phenotype in alveolar macrophages (AM) in the treatment of lung metastases. METHODS: Cytotoxicity assay has been used to assess the capability of AM, in vitro treated of not with 1,25(OH)2D3, to stimulate NK cells. Sulforhodamine B (SRB) assay has been used to assess the effect of 1,25(OH)2D3 on MC-38 and B16 tumor cells in vitro growth. 1,25(OH)2D3 was aerosolized in immunocompetent mouse models to evaluate the effect of local administration of 1,25(OH)2D3 on in vivo growth of MC-38 and B16 tumor cells within lungs and on infiltrating immune cells. RESULTS: In vitro incubation of naïve AM with 1,25(OH)2D3 improved their ability to stimulate NK cell cytotoxicity. In vivo aerosolized 1,25(OH)2D3 significantly reduced the metastatic growth of MC-38 colon carcinoma, a tumor histotype that frequently metastasizes to lung in human. Immune infiltrate obtained from digested lungs of 1,25(OH)2D3-treated mice bearing MC-38 metastases revealed an increased expression of MHCII and CD80 on AM and an up-modulation of CD69 expression on effector cells that paralleled a strong increased ability of these cells to kill MC-38 tumor in vitro. CONCLUSIONS: Together, these data show that aerosol delivery can represent a feasible and novel approach to supplement 1,25(OH)2D3 directly to the lungs promoting the activation of local immunity against cancer.

Macrophages Impair TLR9 Agonist Antitumor Activity through Interacting with the Anti-PD-1 Antibody Fc Domain.

BACKGROUND: A combination of TLR9 agonists and an anti-PD-1 antibody has been reported to be effective in immunocompetent mice but the role of innate immunity has not yet been completely elucidated. Therefore, we investigated the contribution of the innate immune system to this combinatorial immunotherapeutic regimens using an immunodeficient mouse model in which the effector functions of innate immunity can clearly emerge without any interference from T lymphocytes. METHODS: Athymic mice xenografted with IGROV-1 human ovarian cells, reported to be sensitive to TLR9 agonist therapy, were treated with cytosine-guanine (CpG)-oligodeoxynucleotides (ODNs), an anti-PD-1 antibody or their combination. RESULTS: We found that PD-1 blockade dampened CpG-ODN antitumor activity. In vitro studies indicated that the interaction between the anti-PD-1 antibody fragment crystallizable (Fc) domain and macrophage Fc receptors caused these immune cells to acquire an immunoregulatory phenotype, contributing to a decrease in the efficacy of CpG-ODNs. Accordingly, in vivo macrophage depletion abrogated the detrimental effect exerted by the anti-PD-1 antibody. CONCLUSION: Our data suggest that if TLR signaling is active in macrophages, coadministration of an anti-PD-1 antibody can reprogram these immune cells towards a polarization state able to negatively affect the immune response and eventually promote tumor growth.

Gut Microbiota Condition the Therapeutic Efficacy of Trastuzumab in HER2-Positive Breast Cancer.

Emerging evidence indicates that gut microbiota affect the response to anticancer therapies by modulating the host immune system. In this study, we investigated the impact of gut microbiota on immune-mediated trastuzumab antitumor efficacy in preclinical models of HER2-positive breast cancer and in 24 patients with primary HER2-positive breast cancer undergoing trastuzumab-containing neoadjuvant treatment. In mice, the antitumor activity of trastuzumab was impaired by antibiotic administration or fecal microbiota transplantation from antibiotic-treated donors. Modulation of the intestinal microbiota was reflected in tumors by impaired recruitment of CD4+ T cells and granzyme B-positive cells after trastuzumab treatment. Antibiotics caused reductions in dendritic cell (DC) activation and the release of IL12p70 upon trastuzumab treatment, a mechanism that was necessary for trastuzumab effectiveness in our model. In patients, lower α-diversity and lower abundance of Lachnospiraceae, Turicibacteraceae, Bifidobacteriaceae, and Prevotellaceae characterized nonresponsive patients (NR) compared with those who achieved pathologic complete response (R), similar to antibiotic-treated mice. The transfer of fecal microbiota from R and NR into mice bearing HER2-positive breast cancer recapitulated the response to trastuzumab observed in patients. Fecal microbiota ß-diversity segregated patients according to response and positively correlated with immune signature related to interferon (IFN) and NO2-IL12 as well as activated CD4+ T cells and activated DCs in tumors. Overall, our data reveal the direct involvement of the gut microbiota in trastuzumab efficacy, suggesting that manipulation of the gut microbiota is an optimal future strategy to achieve a therapeutic effect or to exploit its potential as a biomarker for treatment response. SIGNIFICANCE: Evidence of gut microbiota involvement in trastuzumab efficacy represents the foundation for new therapeutic strategies aimed at manipulating commensal bacteria to improve response in trastuzumab-resistant patients.See related commentary by Sharma, p. 1937 GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/8/2195/F1.large.jpg.

Intestinal glucose uptake protects liver from lipopolysaccharide and D-galactosamine, acetaminophen, and alpha-amanitin in mice.

We have recently observed that oral administration of D-glucose saves animals from lipopolysaccharide (LPS)-induced death. This effect is the likely consequence of glucose-induced activation of the sodium-dependent glucose transporter-1. In this study, we investigated possible hepatoprotective effects of glucose-induced, sodium-dependent, glucose transporter-1 activation. We show that oral administration of D-glucose, but not of either D-fructose or sucrose, prevents LPS-induced liver injury, as well as liver injury and death induced by an overdose of acetaminophen. In both of these models, physiological liver morphology is maintained and organ protection is confirmed by unchanged levels of the circulating markers of hepatotoxicity, such as alanine transaminase or lactate dehydrogenase. In addition, D-glucose was found to protect the liver from alpha-amanitin-induced liver injury. In this case, in contrast to the previously described models, a second signal had to be present in addition to glucose to achieve protective efficacy. Toll-like receptor 4 stimulation that was induced by low doses of LPS was identified as such a second signal. Eventually, the protective effect of orally administered glucose on liver injury induced by LPS, overdose of acetaminophen, or alpha-amanitin was shown to be mediated by the anti-inflammatory cytokine interleukin-10. These findings, showing glucose-induced protective effects in several animal models of liver injury, might be relevant in view of possible therapeutic interventions against different forms of acute hepatic injury.

Influence of lignans depletion on murine mammary gland morphology.

Different studies have focused on the effects of phytoestrogens-supplemented diets on mammary gland morphogenesis and breast cancer risk; however, particular dieting behaviors and food choices may result in a reduction of the natural source of phytoestrogens. The evaluation of a reduced phytoestrogens intake effect by depletion without modifying other dietary ingredients is hard. Since lignans, the largest contributors to phytoestrogens intake in Western diets, are metabolized into bioactive compounds by gut bacteria, long-term antibiotic treatments, inducing intestinal microflora disruption, may reduce enterolactone availability. To elucidate the effect of phytoestrogens lack on mammary tissue morphogenesis, female FVB mice were treated with gentamicin or metronidazole/ciprofloxacin from the age of 6 to 7 wk. After 21 wk, enterolactone urine levels were 120.07 +/- 20.5 ng/ml in untreated mice, 30.4 +/- 24.46 ng/ml in metronidazole/ciprofloxacin-treated mice, and 3.29 +/- 4.38 ng/ml in gentamicin-treated mice. Histological analysis revealed no significant alterations of mammary morphology in metronidazole/ciprofloxacin-treated mice, whereas gentamicin-treated mice showed increase of ducts number and duct-tree branching vs. controls. These findings indicate that normal mammary tissue size and shape are maintained even in the presence of low levels of lignans and suggest that only a complete depletion of these compounds induced significant alterations of mammary gland structure.