Response In Microenvironment Research Articles

Systematic Screening of Chemokines to Identify Candidates to Model and Create Ectopic Lymph Node Structures for Cancer Immunotherapy

The induction of ectopic lymph node structures (ELNs) holds great promise to augment immunotherapy against multiple cancers including metastatic melanoma, in which ELN formation has been associated with a unique immune-related gene expression signature composed of distinct chemokines. To investigate the therapeutic potential of ELNs induction, preclinical models of ELNs are needed for interrogation of these chemokines. Computational models provide a non-invasive, cost-effective method to investigate leukocyte trafficking in the tumor microenvironment, but parameterizing such models is difficult due to differing assay conditions and contexts among the literature. To better achieve this, we systematically performed microchemotaxis assays on purified immune subsets including human pan-T cells, CD4+ T cells, CD8+ T cells, B cells, and NK cells, with 49 recombinant chemokines using a singular technique, and standardized conditions resulting in a dataset representing 238 assays. We then outline a groundwork computational model that can simulate cellular migration in the tumor microenvironment in response to a chemoattractant gradient created from stromal, lymphoid, or antigen presenting cell interactions. The resulting model can then be parameterized with standardized data, such as the dataset presented here, and demonstrates how a computational approach can help elucidate developing ELNs and their impact on tumor progression.

The inhibitory checkpoint, PD-L2, is a target for effector T cells: Novel possibilities for immune therapy

ABSTRACTCell surface molecules of the B7/CD28 family play an important role in T-cell activation and tolerance. The relevance of the PD-1/PD-L1 pathway in cancer has been extensively studied whereas PD-L2 has received less attention. However, recently the expression of PD-L2 was described to be independently associated with clinical response in anti-PD1-treated cancer patients. Here, we investigated whether PD-L2 might represent a natural target that induces specific T cells. We identified spontaneous specific T-cell reactivity against two epitopes located in the signal peptide of PD-L2 from samples from patients with cancer as well as healthy individuals ex vivo. We characterized both CD8+ and CD4+ PD-L2-specific T cells. Interestingly, the epitope in PD-L2 that elicited the strongest response was equivalent to a potent HLA-A2-restricted epitope in PD-L1. Importantly, PD-L1-specific and PD-L2-specific T cells did not cross-react; therefore, they represent different T-cell antigens. Moreover, PD-L2-specific T cells reacted to autologous target cells depending on PD-L2 expression. These results suggested that activating PD-L2 specific T cells (e.g., by vaccination) might be an attractive strategy for anti-cancer immunotherapy. Accordingly, PD-L2 specific T cells can directly support anti-cancer immunity by killing of target cells, as well as, indirectly, by releasing pro-inflammatory cytokines at the microenvironment in response to PD-L2-expressing immune supressive cells.

Tumor-educated mesenchymal stem cells promote pro-metastatic phenotype.

Multipotent mesenchymal stem cells (MSCs) are recruited into tumor microenvironment in response to multiple signals produced by cancer cells. Molecules involved in their homing to tumors are the same inflammatory mediators produced by injured tissues: chemokines, cytokines and growth factors. When MSCs arrive into the tumor microenvironment these are “educated” to have pro-metastatic behaviour. Firstly, they promote cancer immunosuppression modulating both innate and adaptive immune systems. Moreover, tumor associated-MSCs trans-differentiating into cancer-associated fibroblasts can induce epithelial-mesenchymal-transition program in tumor cells. This process determinates a more aggressive phenotype of cancer cells by increasing their motility and invasiveness and favoring their dissemination to distant sites. In addition, MSCs are involved in the formation and modelling of pre-metastatic niches creating a supportive environment for colonization of circulating tumor cells.The development of novel therapeutic approaches targeting the different functions of MSCs in promoting tumor progression as well as the mechanisms underlying their activities could enhance the efficacy of conventional and immune anti-cancer therapies.Furthermore, many studies report the use of MSCs engineered to express different genes or as vehicle to specifically deliver novel drugs to tumors exploiting their strong tropism. Importantly, this approach can enhance local therapeutic efficacy and reduce the risk of systemic side effects.

Abstract 3617: A paradigm shift for insulin-like growth factor 1 receptor function in triple negative breast cancers

Abstract Signaling through the insulin-like growth factor type 1 receptor (IGF-1R) is complex in breast cancers. Early studies reported that expression of the IGF-1R correlated with estrogen receptor (ER) expression and predicted a favorable phenotype. Moreover, loss of IGF-1R has been associated with breast tumor progression into a more undifferentiated phenotype. We have generated and characterized a mouse line containing both MMTV-Wnt1 and MMTV-dnIGF-1R (kinase dead-IGF-1R) transgenes (referred to subsequently as bigenic mice) that leads to increased mammary tumor initiation and metastasis. These data support the hypothesis that the IGF-1R functions in suppressing metastasis in certain contexts and subtypes of triple negative breast cancers (TNBCs). Recent analyses of TCGA human datasets support the relevance of our model in human TNBCs that have reduced IGF-1R expression and increased expression of Wnt1 and the Frizzled co-receptor Lrp6. We have identified alterations in a number of target genes that potentially regulate metastasis in the bigenic primary tumors including increases in interleukin-6 (IL-6), Slug, Vimentin, Zeb 1/2 and decreases in E-cadherin expression as assessed by Qiagen specific qPCR and single gene qPCR. Furthermore, a subset of anti-inflammatory chemokines and cytokines were assessed by a targeted qPCR array revealing increases in interleukin-4, interleukin-10, and C-C motif chemokine ligand-2 and decreases in tumor necrosis factor-alpha in the bigenic tumors indicating a tumor associated macrophage phenotype. By flow cytometry analysis, the ratio of CD4+ T cells to CD8+ T cells is increased in the bigenic tumors suggesting a tumor promoting immune microenvironment. However, increased expression of IL-6 in the bigenic tumors is specific to the luminal tumor cells, and inhibition of IGF-1R in the MCF7 human breast cancer cell line results in increases in IL-6, Slug, and Zeb 1/2 expression suggesting the tumor cells activate EMT and a pro-tumorigenic microenvironment in response to decreased IGF-1R. Moreover, inhibition of IGF-1R in human breast cancer cells and MMTV-Wnt1 mouse tumor cells results in increased cell motility and invasion as assessed by the xCELLigence motility assay. Taken together, our data support the hypothesis that IGF-1R acts as a negative regulator of mediators that promote migration, invasion, and metastasis in TNBCs. Citation Format: Alison Obr, Sushil Kumar, Raymond Birge, Teresa Wood. A paradigm shift for insulin-like growth factor 1 receptor function in triple negative breast cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3617. doi:10.1158/1538-7445.AM2017-3617

Anaphylatoxins Activate Ca2+, Akt/PI3-Kinase, and FOXO1/FoxP3 in the Retinal Pigment Epithelium.

The retinal pigment epithelium (RPE) is a main target for complement activation in age-related macular degeneration (AMD). The anaphylatoxins C3a and C5a have been thought to mostly play a role as chemoattractants for macrophages and immune cells; here, we explore whether they trigger RPE alterations. Specifically, we investigated the RPE as a potential immunoregulatory gate, allowing for active changes in the RPE microenvironment in response to complement. In vitro and in vivo analysis of signaling pathways. Individual activities of and interaction between the two anaphylatoxin receptors were tested in cultured RPE cells by fluorescence microscopy, western blot, and immunohistochemistry. Intracellular free calcium, protein phosphorylation, immunostaining of tissues/cells, and multiplex secretion assay. Similar to immune cells, anaphylatoxin exposure resulted in increases in free cytosolic Ca2+, PI3-kinase/Akt activation, FoxP3 and FOXO1 phosphorylation, and cytokine/chemokine secretion. Differential responses were elicited depending on whether C3a and C5a were co-administered or applied consecutively, and response amplitudes in co-administration experiments ranged from additive to driven by C5a (C3a + C5a = C5a) or being smaller than those elicited by C3a alone (C3a + C5a < C3a). We suggest that this combination of integrative signaling between C3aR and C5aR helps the RPE to precisely adopt its immune regulatory function. These data further contribute to our understanding of AMD pathophysiology.

Osteocytes Acidify Their Microenvironment in Response to PTHrP In Vitro and in Lactating Mice In Vivo.

Osteocytes appear to mobilize calcium within minutes in response to PTH injections; we have previously shown that osteocytes remove their perilacunar matrix during lactation through activation of the PTH type 1 receptor. Mechanisms utilized by osteocytes to mobilize calcium are unknown but we hypothesized that the molecular components may be similar to those used by osteoclasts. Here we show, using IDG-SW3 cells that ATP6V0D2, an essential component of vacuolar ATPase in osteoclasts, and other genes associated with osteoclastic bone resorption, increase with osteoblast to osteocyte differentiation. Furthermore, PTHrP increases ATP6V0D2 expression and induces proton generation by primary osteocytes, which is blocked by bafilomycin, a vacuolar ATPase inhibitor. These in vitro proton measurements raised the question of osteocyte viability in an acidic environment. Interestingly, osteocytes, showed enhanced viability at pH as low as 5 compared to osteoblasts and fibroblasts in vitro. To study in vivo acidification by osteocytes, virgin and lactating CD1 mice on a low calcium diet were injected with the pH indicator dye, acridine orange, and their osteocyte lacuno-canalicular system imaged by confocal microscopy. Lower pH was observed in lactating compared to virgin animals. In addition, a novel transgenic mouse line with a topaz variant of green fluorescent protein (GFPtpz)-tagged collagen α2(I) chain was used. Instead of the expected reduction in GFP-fluorescence only in the perilacunar matrix, reduced fluorescence was observed in the entire bone matrix of lactating mice. Based on our experiments showing quenching of GFP in vitro, we propose that the observed reduction in GFP fluorescence in lactating mice is due to quenching of GFP by the acidic pH generated by osteocytes. Together these findings provide novel mechanistic insight into how osteocytes remove calcium from their perilacunar/pericanalicular matrices through active acidification of their microenvironment and show that osteocytes, like osteoclasts, are resistant to the negative effects of acid on viability. © 2017 American Society for Bone and Mineral Research.

Resident Memory T cells in the liver Receive the Local Survival factors from the Specialized microenvironments in Response to Acute Viral Infection

Abstract Memory T (TM) cells provide long-term protection against the same infectious agents by maintaining their cell number and responding vigorously upon rechallenge. However, it remains to be investigated which type of TM cells are formed in the liver and how they maintain their homeostasis in response to systemic acute infections. Here, we show that virus-specific TM precursors were clustered in specialized anatomic microenvironments, called lymphoid aggregates. These cells did not circulate in the steady state, suggesting that they are resident in the lymphoid aggregates. We confirmed that TM cells in the liver did not migrate into the secondary lymphoid organs during recall responses. We further characterized the phenotypes of cells found in the lymphoid aggregates using immunofluorescent microscope. TM cells localized in these microenvironments are CXCR3+ and surrounding macrophages (Mø) showed the expression of CX3CR1. These Mø were purified based on the intensity of CX3CR1 expression and examined for expression of potential factors important for the homeostasis of TM cells. Compared to CX3CR1lo cells, CX3CR1hi or CX3CR1int Mø expressed inhibitory receptors, programmed death (PD) protein 1 and PD-ligand 1, and higher mRNA levels of chemokines, CXCL9 and CXCL10, which can induce the recruitment of CXCR3+ cells. These Mø also transcribed high level of interleukin (IL)-15 which is well-defined survival factors for TM cells, and the size of lymphoid aggregates decreased in IL-15-deficient mice. Therefore, we propose that CXCR3+ resident TM cells develop in the liver during acute viral infection, and the specialized Mø in the lymphoid aggregates provide important factors for the homeostasis of these TM cells.

Abstract P4-04-01: A paradigm shift for insulin-like growth factor-1 receptor function in triple negative breast cancers

Abstract Loss of insulin growth factor (IGF) signaling in the mammary gland at puberty leads to delayed elongation and defects in terminal end bud (TEB) proliferation. Moreover, IGF signaling is essential for epithelial mesenchymal interactions in mammary bud morphogenesis. We have generated and characterized a mouse line containing both MMTV-Wnt1 and MMTV-dnIGF-1R (kinase dead-IGF-1R) transgenes (referred to subsequently as bigenic mice) that leads to increased mammary tumor initiation and metastasis1. Recent analyses of TCGA human datasets support the relevance of our model in human triple negative breast cancers (TNBCs) that have reduced IGF-1R expression and increased expression of Wnt1 and the Frizzled co-receptor Lrp6. We have identified alterations in a number of target genes that potentially regulate metastasis in the bigenic primary tumors including increases in interleukin-6 (IL-6), Nanog, Slug, and decreases in E-cadherin expression as assessed by Qiagen specific qPCR and single gene qPCR. Furthermore, a subset of anti-inflammatory chemokines and cytokines were assessed by a targeted qPCR array revealing increases in interleukin-4, interleukin-10, and C-C motif chemokine ligand-2 and decreases in tumor necrosis factor-alpha and interleukin-1 in the bigenic tumors suggesting a tumor associated macrophage phenotype. By flow cytometry analysis, the ratio of CD4+ T cells to CD8+ T cells is increased in the bigenic tumors suggesting a tumor promoting immune microenvironment. However, increased expression of IL-6 in the bigenic tumors is specific to the luminal tumor cells, and inhibition of IGF-1R in the MCF7 human breast cancer cell line results in increases in both IL-6 and Slug expression suggesting the tumor cells activate EMT and a pro-tumorigenic microenvironment in response to decreased IGF-1R. Taken together, our data suggest IGF-1R acts as a negative regulator of mediators that promote invasion and metastasis in TNBCs.

Rejection versus escape: the tumor MHC dilemma.

Most tumor cells derive from MHC-I-positive normal counterparts and remain positive at early stages of tumor development. T lymphocytes can infiltrate tumor tissue, recognize and destroy MHC class I (MHC-I)-positive cancer cells ("permissive" phase I). Later, MHC-I-negative tumor cell variants resistant to T-cell killing emerge. During this process, tumors first acquire a heterogeneous MHC-I expression pattern and finally become uniformly MHC-I-negative. This stage (phase II) represents a "non-permissive" encapsulated structure with tumor nodes surrounded by fibrous tissue containing different elements including leukocytes, macrophages, fibroblasts, etc. Molecular mechanisms responsible for total or partial MHC-I downregulation play a crucial role in determining and predicting the antigen-presenting capacity of cancer cells. MHC-I downregulation caused by reversible ("soft") lesions can be upregulated by TH1-type cytokines released into the tumor microenvironment in response to different types of immunotherapy. In contrast, when the molecular mechanism of the tumor MHC-I loss is irreversible ("hard") due to a genetic defect in the gene/s coding for MHC-I heavy chains (chromosome 6) or beta-2-microglobulin (B2M) (chromosome 15), malignant cells are unable to upregulate MHC-I, remain undetectable by cytotoxic T-cells, and continue to grow and metastasize. Based on the tumor MHC-I molecular analysis, it might be possible to define MHC-I phenotypes present in cancer patients in order to distinguish between non-responders, partial/short-term responders, and likely durable responders. This highlights the need for designing strategies to enhance tumor MHC-I expression that would allow CTL-mediated tumor rejection.

Multi-scale mathematical modelling of tumour growth and microenvironments in anti-angiogenic therapy.

BackgroundAngiogenesis, a process of generation of new blood vessels from the pre-existing vasculature, has been demonstrated to be a basic prerequisite for sustainable growth and proliferation of tumour. Anti-angiogenic treatments show normalization of tumour vasculature and microenvironment at least transiently in both preclinical and clinical settings.MethodsIn this study, we proposed a multi-scale mathematical model to simulate the dynamic changes of tumour microvasculature and microenvironment in response to anti-angiogenic drug endostatin (ES). We incorporated tumour growth, angiogenesis and vessel remodelling at tissue level, by coupling tumour cell phenotypes and endothelial cell behaviour in response to local chemical and haemodynamical microenvironment.ResultsComputational simulation results showed the tumour morphology and growth curves in general tumour progression and following different anti-angiogenic drug strategies. Furthermore, different anti-angiogenic drug strategies were designed to test the influence of ES on tumour growth and morphology. The largest reduction of tumour size was found when ES is injected at simulation time 100, which was concomitant with the emergence of angiogenesis phase.ConclusionThe proposed model not only can predict detailed information of chemicals distribution and vessel remodelling, but also has the potential to specific anti-angiogenic drugs by modifying certain functional modules.

Microenvironments created by liquid-liquid phase transition control the dynamic distribution of bacterial division FtsZ protein.

The influence of membrane-free microcompartments resulting from crowding-induced liquid/liquid phase separation (LLPS) on the dynamic spatial organization of FtsZ, the main component of the bacterial division machinery, has been studied using several LLPS systems. The GTP-dependent assembly cycle of FtsZ is thought to be crucial for the formation of the septal ring, which is highly regulated in time and space. We found that FtsZ accumulates in one of the phases and/or at the interface, depending on the system composition and on the oligomerization state of the protein. These results were observed both in bulk LLPS and in lipid-stabilized, phase-separated aqueous microdroplets. The visualization of the droplets revealed that both the location and structural arrangement of FtsZ filaments is determined by the nature of the LLPS. Relocation upon depolymerization of the dynamic filaments suggests the protein may shift among microenvironments in response to changes in its association state. The existence of these dynamic compartments driven by phase transitions can alter the local composition and reactivity of FtsZ during its life cycle acting as a nonspecific modulating factor of cell function.

Stromal ETS2 Regulates Chemokine Production and Immune Cell Recruitment during Acinar-to-Ductal Metaplasia

Preclinical studies have suggested that the pancreatic tumor microenvironment both inhibits and promotes tumor development and growth. Here we establish the role of stromal fibroblasts during acinar-to-ductal metaplasia (ADM), an initiating event in pancreatic cancer formation. The transcription factor V-Ets avian erythroblastosis virus E26 oncogene homolog 2 (ETS2) was elevated in smooth muscle actin–positive fibroblasts in the stroma of pancreatic ductal adenocarcinoma (PDAC) patient tissue samples relative to normal pancreatic controls. LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx-1-Cre (KPC) mice showed that ETS2 expression initially increased in fibroblasts during ADM and remained elevated through progression to PDAC. Conditional ablation of Ets-2 in pancreatic fibroblasts in a KrasG12D-driven mouse ADM model decreased the amount of ADM events. ADMs from fibroblast Ets-2–deleted animals had reduced epithelial cell proliferation and increased apoptosis. Surprisingly, fibroblast Ets-2 deletion significantly altered immune cell infiltration into the stroma, with an increased CD8+ T-cell population, and decreased presence of regulatory T cells (Tregs), myeloid-derived suppressor cells, and mature macrophages. The mechanism involved ETS2-dependent chemokine ligand production in fibroblasts. ETS2 directly bound to regulatory sequences for Ccl3, Ccl4, Cxcl4, Cxcl5, and Cxcl10, a group of chemokines that act as potent mediators of immune cell recruitment. These results suggest an unappreciated role for ETS2 in fibroblasts in establishing an immune-suppressive microenvironment in response to oncogenic KrasG12D signaling during the initial stages of tumor development.

Abstract 5128: Characterization of tumor immune microenvironment in response to PD-L1 therapy initiated at different time points post inoculation in syngeneic mouse models

Abstract The tumor microenvironment is an important aspect of cancer biology that contributes to tumor initiation, progression and responses to therapy. Cells and molecules of the immune system are fundamental components of the tumor microenvironment which have been known to vary widely and are important in determining the anti-tumor immune response. The approval of immune checkpoint inhibitors like PD-1 and CTLA-4 antibodies has resulted in a lot of research activity in immune-oncology. Syngeneic mouse models have been utilized to understand the preclinical immune response as a surrogate to the clinical response. The timing of immune checkpoint inhibitor dosing is supposed to play an important role on the tumor growth in mouse models. In order to understand the correlation of tumor regression, survival and immune response in a preclinical mouse model, we evaluated the effect of different times of treatment initiation with Program Death Ligand-1 (PD-L1) on tumor volume, survival and tumor infiltrating leukocytes (TIL’s). Various dosing regimens evaluated included initiation of PD-L1 therapy on the day of inoculation, 6 and 12 days post inoculation. Tumors were collected from three different syngeneic mouse models (CT26, RENCA and B16F10) and profiled for the presence of tumor infiltrating leukocytes (TIL’s) using flow cytometry. Major sub-population of TIL's examined included T-regulatory cells (Treg’s), Tumor Associated Macrophages (TAM’s) and Myeloid Derived Suppressor Cells (MDSC’s). Finally, an attempt was made to identify any correlation or lack thereof between tumor growth and tumor immune microenvironment. Citation Format: Geeta Sharma, Susan Wu, Robert Mihalek, Ann Fiore, Matthew Gale, Christa Dias, Wendy Grant, Nidia Hernandez. Characterization of tumor immune microenvironment in response to PD-L1 therapy initiated at different time points post inoculation in syngeneic mouse models. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5128.

Ocular diseases: immunological and molecular mechanisms.

Many factors, such as environmental, microbial and endogenous stress, antigen localization, can trigger the immunological events that affect the ending of the diverse spectrum of ocular disorders. Significant advances in understanding of immunological and molecular mechanisms have been researched to improve the diagnosis and therapy for patients with ocular inflammatory diseases. Some kinds of ocular diseases are inadequately responsive to current medications; therefore, immunotherapy may be a potential choice as an alternative or adjunctive treatment, even in the prophylactic setting. This article first provides an overview of the immunological and molecular mechanisms concerning several typical and common ocular diseases; second, the functions of immunological roles in some of systemic autoimmunity will be discussed; third, we will provide a summary of the mechanisms that dictate immune cell trafficking to ocular local microenvironment in response to inflammation.

Vaccinia vaccine-based immunotherapy arrests and reverses established pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a fatal disease without any cure. Both human disease and animal models demonstrate dysregulated wound healing and unregulated fibrogenesis in a background of low-grade chronic T lymphocyte infiltration. Tissue-resident memory T cells (Trm) are emerging as important regulators of the immune microenvironment in response to pathogens, and we hypothesized that they might play a role in regulating the unremitting inflammation that promotes lung fibrosis. Herein, we demonstrate that lung-directed immunotherapy, in the form of i.n. vaccination, induces an antifibrotic T cell response capable of arresting and reversing lung fibrosis. In mice with established lung fibrosis, lung-specific T cell responses were able to reverse established pathology - as measured by decreased lung collagen, fibrocytes, and histologic injury - and improve physiologic function. Mechanistically, we demonstrate that this effect is mediated by vaccine-induced lung Trm. These data not only have implications for the development of immunotherapeutic regimens to treat IPF, but also suggest a role for targeting tissue-resident memory T cells to treat other tissue-specific inflammatory/autoimmune disorders.

BRAF Inhibition Generates a Host–Tumor Niche that Mediates Therapeutic Escape

The current study defines a fibroblast-derived niche that facilitates the therapeutic escape of melanoma cells from BRAF inhibition. Vemurafenib treatment led to the release of TGF-β from the melanoma cells that increased the differentiation state of the fibroblasts; an affect associated with fibronectin deposition, increase in α-smooth muscle actin (α–SMA) expression and the release of neuregulin (NRG). At the same time, vemurafenib directly activated the fibroblasts through paradoxical stimulation of the MAPK pathway, causing them to secrete hepatocyte growth factor (HGF). Treatment with the BRAF/MEK inhibitor combination reversed the release of HGF. Adhesion of melanoma cells to fibronectin was critical in amplifying the fibroblast-derived NRG and HGF-mediated PI3K/AKT survival signaling in the melanoma cells following BRAF inhibition. In co-culture studies, combination treatment with inhibitors of BRAF/MET/HER kinase was ineffective at reversing the fibroblast-mediated therapeutic escape from BRAF inhibition. Instead, it was noted that combined BRAF/PI3K inhibition overcame fibroblast-mediated drug resistance in vitro and was associated with enhanced anti-tumor effects in an in vivo xenograft model. Thus, we show melanoma cells and fibroblasts remodel their microenvironment in response to BRAF inhibition and that these adaptations allow tumor cells to evade therapy through increased PI3K/AKT survival signaling.

Hematopoietic and nonhematopoietic cells promote Type I interferon- and TLR7-dependent monocytosis during low-dose LCMV infection.

Release of inflammatory monocytes from the bone marrow (BM) into the blood is an important physiological response to infection, but the mechanisms regulating this phenomenon during viral infection are not completely defined. Here, we show that low-dose infection with lymphocytic choriomeningitis virus (LCMV) caused rapid, transient inflammatory monocytosis that required type I interferon (IFN) and Toll-like receptor (TLR) 7 signaling. Type I IFN and TLR7 signals were critical for induction of IFN-stimulated gene expression and CCR2 ligand upregulation in the BM microenvironment in response to LCMV infection. Experiments utilizing BM chimeric mice demonstrated that type I IFN and TLR7 signaling on either hematopoietic or nonhematopoietic cells was sufficient to initiate monocytosis in response to LCMV infection. BM plasmacytoid dendritic cells (pDCs) generated type I IFN directly ex vivo, suggesting that pDCs are a hematopoietic contributor of type I IFN in the BM early during LCMV infection. Overall, we describe novel roles for type I IFN and TLR7 signaling in nonhematopoietic cells and BM pDCs in directing IFN-stimulated gene and CCR2 ligand expression in the BM to initiate an increase in blood inflammatory monocytes during viral infection.

Resistance to Antiangiogenic: Focus on Mechanisms

Angiogenesis is a physiological process involved in the maturation and the development of the tissues, allowing a supply of oxygen and nutrients [1]. This process is stimulated in certain pathological conditions, including carcinogenesis. Angiogenesis has long been regarded as an important target in the treatment of cancer. Much progress has been made in identifying factors involved in angiogenesis, as well as treatment options for many cancers, thanks to antiangiogenic therapies [2, 3]. So it appears that angiogenesis has significant mechanistic complexity, resistance and therapeutic exhaust now are practical limits to the development of drugs [4]. Recent studies in several experimental models suggest that both tumor and non-tumor (stromal) cell types may be involved in the reduced responsiveness to the treatments. The current review focuses on mechanisms, which result in dynamic changes occur in the tumor microenvironment in response to antiangiogenic therapy, resulting in drug resistance. These mechanisms include direct selection of clonal cell populations with the ability to rapidly upregulate other proangiogenic channels, an increased capacity for invasion and an intrinsic resistance to hypoxia [5]. Keywords: Angiogenesis, resistance mecanisms, targeted therapies.

Altered CNS microenvironment in response to systemic infections: A role for microglia?

Bacterial infections are a common cause for morbidity and mortality in the elderly, and in particular in individuals with a neurodegenerative disease. Experimental models of neurodegeneration have shown that LPS-induced systemic inflammation increases neuronal damage, a process that is believed to be mediated by activation of ‘primed’ microglia. The effects of a real systemic bacterial infection on the innate immune cells in the brain are less well described, and therefore, in this study we investigated the alterations in microglia and cerebral endothelial cell phenotype in response to a low grade systemic bacterial infection.

A new inflammatory role for p53 in human macrophages

A new inflammatory role for p53 in human macrophages