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 belong to the Toll-like receptors family, it is mainly expressed on immune cells where it senses pathogen-associated molecular patterns and initiates innate immune response. TLR3 agonist ...poly(I:C) was developed to mimic pathogens infection and boost immune system activation to promote anti-cancer therapy. Accordingly, TLR agonists were included in the National Cancer Institute list of immunotherapeutic agents with the highest potential to cure cancer. Besides well known effects on immune cells, poly(I:C) was also shown, in experimental models, to directly induce apoptosis in cancer cells expressing TLR3.
This review presents the current knowledge on the mechanism of poly(I:C)-induced apoptosis in cancer cells. Experimental evidences on positive or negative regulators of TLR3-mediated apoptosis induced by poly(I:C) are reported and strategies are proposed to successfully promote this event in cancer cells.
Cancer cells apoptosis is an additional arm offered by poly(I:C), besides activation of immune system, for the treatment of various type of cancer. A further dissection of TLR3 signaling would contribute to greater resolution of the critical steps that impede full exploitation of the poly(I:C)-induced apoptosis. Experimental evidences about negative regulator of poly(I:C)-induced apoptotic program should be considered in combinations with TLR3 agonists in clinical trials.
Hyperprogression (HP), a paradoxical boost in tumor growth, was described in a subset of patients treated with immune checkpoint inhibitors (ICI). Neither clinicopathologic features nor biological ...mechanisms associated with HP have been identified.
Among 187 patients with non-small cell lung cancer (NSCLC) treated with ICI at our institute, cases with HP were identified according to clinical and radiologic criteria. Baseline histologic samples from patients treated with ICI were evaluated by IHC for myeloid and lymphoid markers. T-cell-deficient mice, injected with human lung cancer cells and patient-derived xenografts (PDX) belonging to specific mutational subsets, were assessed for tumor growth after treatment with antibodies against mouse and human programmed death receptor-1 (PD-1). The immune microenvironment was evaluated by flow cytometry and IHC.
Among 187 patients, 152 were evaluable for clinical response. We identified four categories: 32 cases were defined as responders (21%), 42 patients with stable disease (27.7%), 39 cases were defined as progressors (25.7%), and 39 patients with HP (25.7%). Pretreatment tissue samples from all patients with HP showed tumor infiltration by M2-like CD163
CD33
PD-L1
clustered epithelioid macrophages. Enrichment by tumor-associated macrophages (TAM) was observed, even in tumor nodules from immunodeficient mice injected with human lung cancer cells and with PDXs. In these models, tumor growth was enhanced by treatment with anti-PD-1 but not anti-PD-1 F(ab)
fragments.
These results suggest a crucial role of TAM reprogramming, upon Fc receptor engagement by ICI, eventually inducing HP and provide clues on a distinctive immunophenotype potentially able to predict HP.
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Pulmonary immunological tolerance to inhaled particulates might create a permissive milieu for lung metastasis. Lung microbiota contribute to pulmonary tolerance; here, we explored whether its ...manipulation via antibiotic or probiotic aerosolization favors immune response against melanoma metastasis. In lungs of vancomycin/neomycin-aerosolized mice, a decrease in bacterial load was associated with reduced regulatory T cells and enhanced T cell and NK cell activation that paralleled a significant reduction of melanoma B16 lung metastases. Reduction of metastases also occurred in lungs transplanted with bacterial isolates from antibiotic-treated lungs. Aerosolized Lactobacillus rhamnosus strongly promoted immunity against B16 lung metastases as well. Furthermore, probiotics or antibiotics improved chemotherapy activity against advanced B16 metastases. Thus, we identify a role for lung microbiota in metastasis and show that its targeting via aerosolization is a therapy that can prevent metastases and enhance responses to chemotherapy.
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•Aerosolized antibiotic reduces lung microbiota and a tolerogenic microenvironment•Aerosol delivery of an antibiotic or probiotic decreases tumor seeding in the lung•Antibiotic or probiotic aerosol improves chemotherapy against experimental metastases
Le Noci et al. reveal that modulation of pulmonary microbiota by antibiotic or probiotic aerosolization decreases tumor growth in the lung. Antibiotic treatment induces a reduction of immunosuppressive cells in the lung, while probiotic administration promotes maturation of resident antigen-presenting cells.
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.
It is amply demonstrated that cigarette smoke (CS) has a high impact on lung tumor progression worsening lung cancer patient prognosis and response to therapies. Alteration of immune cell types and ...functions in smokers' lungs have been strictly related with smoke detrimental effects. However, the role of CS in dictating an inflammatory or immunosuppressive lung microenvironment still needs to be elucidated. Here, we investigated the effect of in vitro exposure to cigarette smoke extract (CSE) focusing on macrophages.
Immortalized murine macrophages RAW 264.7 cells were cultured in the presence of CS extract and their polarization has been assessed by Real-time PCR and cytofluorimetric analysis, viability has been assessed by SRB assay and 3D-cultures and activation by exposure to Poly(I:C). Moreover, interaction with Lewis lung carcinoma (LLC1) murine cell models in the presence of CS extract were analyzed by confocal microscopy.
Obtained results indicate that CS induces macrophages polarization towards the M2 phenotype and M2-phenotype macrophages are resistant to the CS toxic activity. Moreover, CS impairs TLR3-mediated M2-M1 phenotype shift thus contributing to the M2 enrichment in lung smokers.
These findings indicate that, in lung cancer microenvironment of smokers, CS can contribute to the M2-phenotype macrophages prevalence by different mechanisms, ultimately, driving an anti-inflammatory, likely immunosuppressive, microenvironment in lung cancer smokers.
Immune checkpoint inhibitors (ICIs) have made a breakthrough in the treatment of different types of tumors, leading to improvement in survival, even in patients with advanced cancers. Despite the ...good clinical results, a certain percentage of patients do not respond to this kind of immunotherapy. In addition, in a fraction of nonresponder patients, which can vary from 4 to 29% according to different studies, a paradoxical boost in tumor growth after ICI administration was observed: a completely unpredictable novel pattern of cancer progression defined as hyperprogressive disease. Since this clinical phenomenon has only been recently described, a universally accepted clinical definition is lacking, and major efforts have been made to uncover the biological bases underlying hyperprogressive disease. The lines of research pursued so far have focused their attention on the study of the immune tumor microenvironment or on the analysis of intrinsic genomic characteristics of cancer cells producing data that allowed us to formulate several hypotheses to explain this detrimental effect related to ICI therapy. The aim of this review is to summarize the most important works that, to date, provide important insights that are useful in understanding the mechanistic causes of hyperprogressive disease. Keywords: Hyperprogressive disease, Immune checkpoint inhibitors, Immunotherapy, Immune-mediated mechanisms
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.
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.
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.
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.
Through whole-transcriptome profiling of HER2+ breast carcinomas (BCs), we previously showed that those sensitive to trastuzumab are addicted to this oncoprotein and are enriched in immune pathways, ...raising the hypothesis that HER2 itself regulates immune cell recruitment. In the present study we investigated the relationship between HER2 activity and the pro-trastuzumab tumor immune milieu. Gene expression profiling and immunohistochemistry analysis of 53 HER2+ BCs showed that trastuzumab-sensitive tumors expressed significantly higher levels of chemokines involved in immune cell recruitment, with higher infiltration of T cells and monocytes, and higher levels of PD-1 ligands than tumors that do not benefit from trastuzumab. In vitro analysis in HER2+ BC cells revealed that CCL2 production was induced by HER2 stimulation with EGF/HRG via the PI3K-NF-kB axis, and down-modulated by HER2 inhibition with trastuzumab. CCL2 expression was higher in HER2+/ER− than HER2+/ER+ BC cell lines, and degradation of ER by fulvestrant induced an enhancement in NF-κB transcriptional activity and consequent CCL2 expression. Trastuzumab efficacy relied on CCL2 levels and monocytes present in the tumor microenvironment in FVB mice bearing HER2+ mammary carcinoma cells. HER2 signals were also found to sustain the expression of PD-1 ligands in tumor cells via the MEK pathway.
Overall, our results support the concept that the activated HER2 oncogene regulates recruitment and activation of tumor infiltrating immune cells and trastuzumab activity by inducing CCL2 and PD-1 ligands and that ER activity negatively controls the HER2-driven pro-trastuzumab tumor microenvironment.
The microbiota is emerging as a key player in cancer due to its involvement in several host physiological functions, including digestion, development of the immune system, and modulation of endocrine ...function. Moreover, its participation in the efficacy of anticancer treatments has been well described. For instance, the involvement of the breast microbiota in breast cancer (BC) development and progression has gained ground in the past several years. In this review, we report and discuss new findings on the impact of the gut and breast microbiota on BC, focusing on the HER2+ BC subtype, and the possibility of defining microbial signatures that are associated with disease aggressiveness, treatment response, and therapy toxicity. We also discuss novel insights into the mechanisms through which microorganism-host interactions occur and the possibility of microbiota editing in the prevention and treatment optimization of BC.
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