Though most behavioral traits are moderately to highly heritable, the genes that influence them are elusive: many published genetic associations fail to replicate. With physical traits like eye color and skin pigmentation, in contrast, several genes with large effects have been discovered and replicated. We draw on R.A. Fisher’s geometric model of adaptation to explain why traits of interest to behavioral scientists may have a genetic architecture featuring hundreds or thousands of alleles with tiny individual effects, rather than a few with large effects, and why such an architecture makes it difficult to find robust associations between traits and genes. In the absence of strong directional selection on a trait, alleles with large effect sizes will probably remain rare, and such a lack of strong directional selection is likely to characterize most traits currently of interest in social science. We evaluate these predictions via a genome-wide association study (GWAS) that carefully measured over 100 physical and behavioral traits with a sample size typical of candidate gene studies. While we replicated several known genetic associations with physical traits, we found only two associations with behavioral traits that met the nominal genome-wide significance threshold. We use the theory and findings to discuss (1) the challenges for social science genomics, particularly the likelihood that genes are connected to behavioral variation by lengthy, nonlinear, interactive causal chains; (2) the prospects for dealing with these challenges; and (3) the inherent tradeoff between two ways of meeting these challenges: increasing sample size and improving phenotype measurement.
Background & Aims
SAMP1/Yit mice develop spontaneous, segmental, transmural ileitis recapitulating many features of Crohn’s disease (CD). The ileitic phenotype may have arisen during crosses of SAMP1 mice selected for the presence of skin lesions. We hereby describe that the original SAMP1 strain similarly develops ileitis. Our aim was to characterize the histopathological and immunological features of this model and assess its responsiveness to standard IBD therapy.
The time course of histopathological features of ileitis was assessed. Immune compartments were characterized by flow cytometry. Ileal cytokine profiles and transcription factors were determined by real-time RT-PCR. Finally, response to corticosteroid therapy and its effect on immune compartments and cellularity was evaluated.
Histological features and time course of disease were conserved, compared to those reported in SAMP1/Yit strains, with similar expansion of CD19+, CD4+ and CD8+ effector (CD44highCD62Llow), and central memory lymphocytes (CD44highCD62Lhigh). However, different from SAMP1/YitFc mice, analysis of ileal cytokine profiles revealed initial TH1 polarization followed by TH2-polarized profile accompanied by prominent eosinophilia during late disease. Lastly, corticosteroids attenuated ileitis resulting in decreased lymphocyte subsets and cellularity of compartments.
Here we report that the ileitic phenotype of SAMP1-related strains was already present in the original SAMP1 strain. By contrast the cytokine profile within terminal ilea of SAMP1 is distinct from the mixed TH1/TH2 profile of SAMP1/YitFc mice during late disease, as it shows predominant TH2 polarization. Dissemination of these strains may advance our understanding of CD pathogenesis, which in 60% of patients involves the terminal ileum.
In order to formulate the Fundamental Theorem of Natural Selection, Fisher defined the average excess and average effect of a gene substitution. Finding these notions to be somewhat opaque, some authors have recommended reformulating Fisher’s ideas in terms of covariance and regression, which are classical concepts of statistics. We argue that Fisher intended his two averages to express a distinction between correlation and causation. On this view, the average effect is a specific weighted average of the actual phenotypic changes that result from physically changing the allelic states of homologous genes. We show that the statistical and causal conceptions of the average effect, perceived as inconsistent by Falconer, can be reconciled if certain relationships between the genotype frequencies and non-additive residuals are conserved. There are certain theory-internal considerations favouring Fisher’s original formulation in terms of causality; for example, the frequency-weighted mean of the average effects equaling zero at each locus becomes a derivable consequence rather than an arbitrary constraint. More broadly, Fisher’s distinction between correlation and causation is of critical importance to gene-trait mapping studies and the foundations of evolutionary biology.
A clear contradiction exists between cytotoxic in-vitro studies demonstrating effectiveness of Gemcitabine to curtail pancreatic cancer and in-vivo studies failing to show Gemcitabine as an effective treatment. The outcome of chemotherapy in metastatic stages, where surgery is no longer viable, shows a 5-year survival <5%. It is apparent that in-vitro experiments, no matter how well designed, may fail to adequately represent the complex in-vivo microenvironmental and phenotypic characteristics of the cancer, including cell proliferation and apoptosis. We evaluate in-vitro cytotoxic data as an indicator of in-vivo treatment success using a mathematical model of tumor growth based on a dimensionless formulation describing tumor biology. Inputs to the model are obtained under optimal drug exposure conditions in-vitro. The model incorporates heterogeneous cell proliferation and death caused by spatial diffusion gradients of oxygen/nutrients due to inefficient vascularization and abundant stroma, and thus is able to simulate the effect of the microenvironment as a barrier to effective nutrient and drug delivery. Analysis of the mathematical model indicates the pancreatic tumors to be mostly resistant to Gemcitabine treatment in-vivo. The model results are confirmed with experiments in live mice, which indicate uninhibited tumor proliferation and metastasis with Gemcitabine treatment. By extracting mathematical model parameter values for proliferation and death from monolayer in-vitro cytotoxicity experiments with pancreatic cancer cells, and simulating the effects of spatial diffusion, we use the model to predict the drug response in-vivo, beyond what would have been expected from sole consideration of the cancer intrinsic resistance. We conclude that this integrated experimental/computational approach may enhance understanding of pancreatic cancer behavior and its response to various chemotherapies, and, further, that such an approach could predict resistance based on pharmacokinetic measurements with the goal to maximize effective treatment strategies.
There are few treatment options for advanced pancreatic cancer. The chemotherapeutic drug Gemcitabine is routinely used, yet 95% of patients die within 5 years of diagnosis. Surprisingly, Gemcitabine experiments with pancreatic tumor cells in the laboratory dish show that most cells will be killed by this drug. It is obvious that the dish does not adequately represent the more complex condition in real tumors. We apply mathematical modeling to simulate tumor growth to try to understand how results from the laboratory could be used to predict the treatment response in real tumors. The model simulates flow of substances such as oxygen within tumors and how this flow affects the response of cells to drug treatment. We set the inputs for the model with values obtained from the laboratory experiments. The model predicts the treatment to mostly fail in real tumors regardless of the characteristics of individual cells. We confirm these results by treating real tumors in mice, showing that our integrated experimental/computational approach may improve the understanding of pancreatic cancer behavior and response to chemotherapy, and also help to optimize treatment strategies.
Eosinophils are blood cells that are often found in high numbers in the tissues of allergic conditions and helminthic parasite infections. The pathophysiological roles that eosinophils may serve in other human ‘eosinophil-associated’ diseases remain obscure.
NIH Institutes and the Office of Disease Prevention assembled an international taskforce of clinical and basic scientists with the charge to propose and prioritize unmet research needs in eosinophil-associated diseases.
The taskforce used an organ system approach to dissect out the different and common themes of eosinophil cell involvement in these diseases. In early 2012, a draft document was circulated for review. The document was amended and the prioritizations were set at a NIH-organized workshop in June 2012.
The taskforce identified significant research needs. These needs cross disease entities but some are disease-specific. There are substantial shortcomings to the various preclinical animal models, as well as significant gaps in our epidemiologic, pathophysiologic, diagnostic, prognostic and therapeutic knowledge. The taskforce recognized that recent efforts by patient advocacy groups have played instrumental roles in improving the identification and characterization of these disorders. However, communication amongst the eosinophil interested communities, e.g., governmental funding and regulatory agencies, and industry and clinician scientists need to be more comprehensive.
Significant efforts are required to address our knowledge gaps in order to improve the outcomes of eosinophil-associated diseases. NIH Institutes, other federal agencies, lay organizations and the pharmaceutical industry should consider the taskforce’s recommendations in their future research activities.
eosinophil; apoptosis; therapeutics; research; discovery; fusion oncoproteins; hypereosinophilic syndromes; Churg-Strauss syndrome; coagulopathy
The respective life histories of humans and mice are well defined and describe a unique story of evolutionary conservation extending from sequence identity within the genome to the underpinnings of biochemical, cellular, and physiological pathways. As a consequence, the hematopoietic lineages of both species are invariantly maintained, each with identifiable eosinophils. This canonical presence nonetheless does not preclude disparities between human and mouse eosinophils and/or their effector functions. Indeed, many books and reviews dogmatically highlight differences, providing a rationale to discount the use of mouse models of human eosinophilic diseases. We suggest that this perspective is parochial and ignores the wealth of available studies and the consensus of the literature that overwhelming similarities (and not differences) exist between human and mouse eosinophils. The goal of this review is to summarize this literature and in some cases provide the experimental details, comparing and contrasting eosinophils and eosinophil effector functions in humans vs. mice. In particular, our review will provide a summation and an easy to use reference guide to important studies demonstrating that while differences exist, more often than not their consequences are unknown and do not necessarily reflect inherent disparities in eosinophil function, but instead, species-specific variations. The conclusion from this overview is that despite nominal differences, the vast similarities between human and mouse eosinophils provide important insights as to their roles in health and disease and, in turn, demonstrate the unique utility of mouse-based studies with an expectation of valid extrapolation to the understanding and treatment of patients.
eosinophils; mouse; human; rodent; primate; hematology
The genetic and physiological similarities between mice and humans have focused considerable attention on rodents as potential models of human health and disease. Together with the wealth of resources, knowledge, and technologies surrounding the mouse as a model system, these similarities have propelled this species to the forefront of biomedical research. The advent of genomic manipulation has quickly led to the creation and use of genetically engineered mice as powerful tools for cutting edge studies of human disease research, including the discovery, refinement, and utility of many currently available therapeutic regimes. In particular, the creation of genetically modified mice as models of human disease has remarkably changed our ability to understand the molecular mechanisms and cellular pathways underlying disease states. Moreover, the mouse models resulting from gene transfer technologies have been important components correlating an individual’s gene expression profile to the development of disease pathologies. The objective of this review is to provide physician-scientists with an expansive historical and logistical overview of the creation of mouse models of human disease through gene transfer technologies. Our expectation is that this will facilitate on-going disease research studies and may initiate new areas of translational research leading to enhanced patient care.
Animal Model; Biomedical Research; Genetic Engineering; Murine; Rodent
Rationale: The immune response in sepsis is characterized by overt immune dysfunction. Studies indicate immunostimulation represents a viable therapy for patients. One study suggests a potentially protective role for interleukin 5 (IL-5) in sepsis; however, the loss of eosinophils in this disease presents a paradox.
Objectives: To assess the protective and eosinophil-independent effects of IL-5 in sepsis.
Methods: We assessed the effects of IL-5 administration on survival, bacterial burden, and cytokine production after polymicrobial sepsis. In addition, we examined the effects on macrophage phagocytosis and survival using fluorescence microscopy and flow cytometry.
Measurements and Main Results: Loss of IL-5 increased mortality and tissue damage in the lung, IL-6 and IL-10 production, and bacterial burden during sepsis. Therapeutic administration of IL-5 improved mortality in sepsis. Interestingly, IL-5 administration resulted in neutrophil recruitment in vivo. IL-5 overexpression in the absence of eosinophils resulted in decreased mortality from sepsis and increased circulating neutrophils and monocytes, suggesting their importance in the protective effects of IL-5. Furthermore, novel data demonstrate IL-5 receptor expression on neutrophils and monocytes in sepsis. IL-5 augmented cytokine secretion, activation, phagocytosis, and survival of macrophages. Importantly, macrophage depletion before the onset of sepsis eliminated IL-5–mediated protection. The protective effects of IL-5 were confirmed in humans, where IL-5 levels were elevated in patients with sepsis. Moreover, neutrophils and monocytes from patients expressed the IL-5 receptor.
Conclusions: Taken together, these data support a novel role for IL-5 on noneosinophilic myeloid populations, and suggest treatment with IL-5 may be a viable therapy for sepsis.
macrophages; neutrophils; innate immunity; immunotherapy
Reports have recently suggested that eosinophils have the potential to modulate allergen-dependent pulmonary immune responses. The studies presented expand these reports demonstrating in the mouse that eosinophils are required for the allergen dependent Th2 pulmonary immune responses mediated by dendritic cells (DC) and T lymphocytes. Specifically, the recruitment of peripheral eosinophils to the pulmonary lymphatic compartment(s) was required for the accumulation of myeloid DCs in draining lymph nodes and, in turn, antigen-specific T effector cell production. These effects on DCs and antigen-specific T cells did not require MHC II expression on eosinophils, suggesting that these granulocytes have an accessory role as opposed to direct T cell stimulation. The data also showed that eosinophils uniquely suppress the DC-mediated production of Th17, and to smaller degree Th1 responses. The cumulative effect of these eosinophil-dependent immune mechanisms is to promote the Th2 polarization characteristic of the pulmonary microenvironment following allergen challenge.
Mouse models of eosinophilic disorders are often part of preclinical studies investigating the underlying biological mechanisms of disease pathology. The presence of extracellular eosinophil granule proteins in affected tissues is a well established and specific marker of eosinophil activation in both patients and mouse models of human disease. Unfortunately, assessments of granule proteins in the mouse have been limited by the availability of specific antibodies and a reliance on assays of released enzymatic activities that are often neither sensitive nor eosinophil specific. The ability to immunologically detect and quantify the presence of a mouse eosinophil granule protein in biological fluids and/or tissue extracts was achieved by the generation of monoclonal antibodies specific for eosinophil peroxidase (EPX). This strategy identified unique pairs of antibodies with high avidity to the target protein and led to the development of a unique sandwich ELISA for the detection of EPX. Full factorial design was used to develop this ELISA, generating an assay that is eosinophil-specific and nearly 10 times more sensitive than traditional OPD-based detection methods of peroxidase activity. The added sensitivity afforded by this novel assay was used to detect and quantify eosinophil degranulation in several setting, including bronchoalveolar fluid from OVA sensitized/challenged mice (an animal model of asthma), serum samples derived from peripheral blood recovered from the tail vasculature, and from purified mouse eosinophils stimulated ex vivo with platelet activating factor (PAF) and PAF + ionomycin. This ability to assess mouse eosinophil degranulation represents a specific, sensitive, and reproducible assay that fulfills a critical need in studies of eosinophil-associated pathologies in mice.
EPX; eosinophilia; granule proteins; allergic inflammation
Eosinophils play important roles in regulation of cellular responses under conditions of homeostasis or infection. Intestinal infection with the parasitic nematode, Trichinella spiralis induces a pronounced eosinophilia that coincides with establishment of larval stages in skeletal muscle. We have shown previously that in mouse strains in which the eosinophil lineage is ablated, large numbers of T. spiralis larvae are killed by nitric oxide, implicating the eosinophil as an immune regulator. In this report, we show that parasite death in eosinophil-ablated mice correlates with reduced recruitment of IL-4+ T cells and enhanced recruitment of iNOS producing neutrophilsto infected muscle, as well as increased iNOS in local F4/80+CD11b+Ly6C+ macrophages. Actively growing T. spiralis larvae were susceptible to killing by NO in vitro, while mature larvae were highly resistant. Growth of larvae was impaired in eosinophil-ablated mice, potentially extending the period of susceptibility to the effects of NO and enhancing parasite clearance. Transfer of eosinophils into eosinophil-ablated ΔdblGATA mice restored larval growth and survival. Regulation of immunity was not dependent upon eosinophil peroxidase (EPO) or major basic protein 1 (MBP) and did not correlate with activity of the indoleamine 2,3-dioxygenase (IDO) pathway. Our results suggest that eosinophils support parasite growth and survival by promoting accumulation of Th2 cells and preventing induction of iNOS in macrophages and neutrophils. These findings begin to define the cellular interactions that occur at an extra-intestinal site of nematode infection in which the eosinophil functions as a pivotal regulator of immunity.
Eosinophils; monocytes/macrophages; Parasitic-Helminth; Trichinella; nitric oxide
Tumor-associated eosinophilia has been observed in numerous human cancers and several tumor models in animals, however, the details surrounding this eosinophilia remain largely undefined and anecdotal. We used a B16-F10 melanoma cell injection model to demonstrate that eosinophil infiltration of tumors occurred from the earliest palpable stages with significant accumulations only in the necrotic and capsule regions. Furthermore, the presence of diffuse extracellular matrix staining for eosinophil major basic protein was restricted to the necrotic areas of tumors indicating that eosinophil degranulation was limited to this region. Antibody-mediated depletion of CD4+ T cells and adoptive transfer of eosinophils suggested, respectively, that the accumulation of eosinophils is not associated with Th2-dependent immune responses and that recruitment is a dynamic ongoing process, occurring throughout tumor growth. Ex vivo migration studies have identified what appears to be a novel chemotactic factor(s) released by stressed/dying melanoma cells, suggesting that the accumulation of eosinophils in tumors occurs, in part, through a unique mechanism dependent on a signal(s) released from areas of necrosis. Collectively, these studies demonstrate that the infiltration of tumors by eosinophils is an early and persistent response that is spatial restricted. More importantly, these data also show that the mechanism(s) that elicits this host response occurs independent of immune surveillance, suggesting that eosinophils are part of an early inflammatory reaction at the site of tumorigenesis.
Eosinophils; Tumor Immunology; Cancer; Mice; B16 Melanoma Cells
Eosinophils and neutrophils contribute to larval killing during the primary immune response, and neutrophils are effector cells in the secondary response to Strongyloides stercoralis in mice. The objective of this study was to determine the molecular mechanisms used by eosinophils and neutrophils to control infections with S. stercoralis. Using mice deficient in the eosinophil granule products major basic protein (MBP) and eosinophil peroxidase (EPO), it was determined that eosinophils kill the larvae through an MBP-dependent mechanism in the primary immune response if other effector cells are absent. Infecting PHIL mice, which are eosinophil deficient, with S. stercoralis resulted in development of primary and secondary immune responses that were similar to those of wild-type mice, suggesting that eosinophils are not an absolute requirement for larval killing or development of secondary immunity. Treating PHIL mice with a neutrophil-depleting antibody resulted in a significant impairment in larval killing. Naïve and immunized mice with neutrophils deficient in myeloperoxidase (MPO) infected with S. stercoralis had significantly decreased larval killing. It was concluded that there is redundancy in the primary immune response, with eosinophils killing the larvae through an MBP-dependent mechanism and neutrophils killing the worms through an MPO-dependent mechanism. Eosinophils are not required for the development or function of secondary immunity, but MPO from neutrophils is required for protective secondary immunity.
Mammalian tooth enamel is often chipped, providing clear evidence for localized contacts with large hard food objects. Here, we apply a simple fracture equation to estimate peak bite forces directly from chip size. Many fossil hominins exhibit antemortem chips on their posterior teeth, indicating their use of high bite forces. The inference that these species must have consumed large hard foods such as seeds is supported by the occurrence of similar chips among known modern-day seed predators such as orangutans and peccaries. The existence of tooth chip signatures also provides a way of identifying the consumption of rarely eaten foods that dental microwear and isotopic analysis are unlikely to detect.
dietary reconstruction; hominid; dentition; fracture
The current paradigm surrounding allergen-mediated T helper type 2 (Th2) immune responses in the lung suggests an almost hegemonic role for T cells. Our studies propose an alternative hypothesis implicating eosinophils in the regulation of pulmonary T cell responses. In particular, ovalbumin (OVA)-sensitized/challenged mice devoid of eosinophils (the transgenic line PHIL) have reduced airway levels of Th2 cytokines relative to the OVA-treated wild type that correlated with a reduced ability to recruit effector T cells to the lung. Adoptive transfer of Th2-polarized OVA-specific transgenic T cells (OT-II) alone into OVA-challenged PHIL recipient mice failed to restore Th2 cytokines, airway histopathologies, and, most importantly, the recruitment of pulmonary effector T cells. In contrast, the combined transfer of OT-II cells and eosinophils into PHIL mice resulted in the accumulation of effector T cells and a concomitant increase in both airway Th2 immune responses and histopathologies. Moreover, we show that eosinophils elicit the expression of the Th2 chemokines thymus- and activation-regulated chemokine/CCL17 and macrophage-derived chemokine/CCL22 in the lung after allergen challenge, and blockade of these chemokines inhibited the recruitment of effector T cells. In summary, the data suggest that pulmonary eosinophils are required for the localized recruitment of effector T cells.
The objective of the present study was to explore the ability of eosinophils to present Strongyloides stercoralis antigen in naive and immunized mice. Antigen-pulsed eosinophils were injected intraperitoneally into naive or immunized mice, and then mice were examined for antigen-specific immune responses. A single inoculation of antigen-pulsed eosinophils was sufficient to prime naive mice and to boost immunized mice for antigen-specific T helper cell type 2 (Th2) immune responses with increased interleukin (IL)– 4 and IL-5 production. Mice inoculated 3 times with live eosinophils pulsed with antigen showed significant increases in parasite antigen–specific immunoglobulin (Ig) M and IgG levels in their serum. Antigen-pulsed eosinophils deficient in major histocompatibility complex class II molecules or antigen-pulsed dead eosinophils failed to induce immune responses, thereby demonstrating the requirement for direct interaction between eosinophils and T cells. These experiments demonstrate that eosinophils function as antigen-presenting cells for the induction of the primary and the expansion of the secondary Th2 immune responses to S. stercoralis in mice.
Hypoxia-inducible factors (HIFs), in particular HIF-1α, have been implicated in tumor biology. However, HIF target genes in the esophageal tumor microenvironment remain elusive. Gene expression profiling was performed upon hypoxia-exposed non-transformed immortalized human esophageal epithelial cells, EPC2-hTERT, and comparing with a gene signature of esophageal squamous cell carcinoma (ESCC). In addition to known HIF-1α target genes such as carbonic anhydrase 9, insulin-like growth factor binding protein-3 (IGFBP3) and cyclooxygenase (COX)-2, prostaglandin E synthase (PTGES) was identified as a novel target gene among the commonly upregulated genes in ESCC as well as the cells exposed to hypoxia. The PTGES induction was augmented upon stabilization of HIF-1α by hypoxia or cobalt chloride under normoxic conditions and suppressed by dominant-negative HIF-1α. Whereas PTGES messenger RNA (mRNA) was negatively regulated by normoxia, PTGES protein remained stable upon reoxygenation. Prostaglandin E2 (PGE2) biosynthesis was documented in transformed human esophageal cells by ectopic expression of PTGES as well as RNA interference directed against PTGES. Moreover, hypoxia stimulated PGE2 production in a HIF-1α-dependent manner. In ESCC, PTGES was overexpressed frequently at the mRNA and protein levels. Finally, COX-2 and PTGES were colocalized in primary tumors along with HIF-1α and IGFBP3. Activation of the COX-2–PTGES axis in primary tumors was further corroborated by concomitant upregulation of interleukin-1β and downregulation of hydroxylprostaglandin dehydrogenase. Thus, PTGES is a novel HIF-1α target gene, involved in prostaglandin E biosynthesis in the esophageal tumor hypoxic microenvironment, and this has implications in diverse tumors types, especially of squamous origin.
This case reports the unique association of eosinophilic gastrointestinal disease with eosinophilic bronchitis, asthma and chronic rhinosinusitis and some features of lymphocytic hypereosinophilic syndrome, describes a diagnostic protocol for patients with asthma and persistent eosinophilic bronchitis, and suggests that the use of a novel EPX-mAb provides a reliable method to identify eosinophilic inflammation.
Eosinophils play important roles in asthma and lung infections. Murine models are widely used for assessing the functional significance and mechanistic basis for eosinophil involvements in these diseases. However, little is known about tissue eosinophils in homeostasis. In addition, little data on eosinophil chemokine production during allergic airway inflammation are available. In this study, the properties and functions of homeostatic and activated eosinophils were compared. Eosinophils from normal tissues expressed costimulation and adhesion molecules B7-1, B7-2 and ICAM-1 for Ag presentation but little major histocompatibility complex (MHC) class II, and were found to be poor stimulators of T-cell proliferation. However, these eosinophils expressed high levels of chemokine mRNA including C10, macrophage inflammatory protein (MIP)-1α, MIP-1γ, MIP-2, eotaxin and monocyte chemoattractant protein-5 (MCP-5), and produced chemokine proteins. Eosinophil intracellular chemokines decreased rapidly with concomitant surface marker downregulation upon in vitro culturing consistent with piecemeal degranulation. Lung eosinophils from mice with induced allergic airway inflammation exhibited increased chemokines mRNA expression and chemokines protein production and upregulated MHC class II and CD11c expression. They were also found to be the predominant producers of the CCR1 ligands CCL6/C10 and CCL9/MIP-1γ in inflamed lungs. Eosinophil production of C10 and MIP-1γ correlated with the marked influx of CD11bhigh lung dendritic cells during allergic airway inflammation and the high of CCR1 on these dendritic cells (DCs). The study provided baseline information on tissue eosinophils, documented the upregulation of activation markers and chemokine production in activated eosinophils, and indicated that eosinophils were a key chemokine-producing cell type in allergic lung inflammation.
allergy; chemokines; eosinophils; lung; mouse
Insulin-like growth factor binding protein (IGFBP)-3 exerts either proapoptotic or growth stimulatory effects depending upon the cellular context. IGFBP-3 is overexpressed frequently in esophageal cancer. Yet, the role of IGFBP-3 in esophageal tumor biology remains elusive. To delineate the functional consequences of IGFBP-3 overexpression, we stably transduced Ha-RasV12-transformed human esophageal cells with either wild-type or mutant IGFBP-3, the latter incapable of binding Insulin-like growth factor (IGFs) as a result of substitution of amino-terminal Ile56, Leu80, and Leu81 residues with Glycine residues. Wild-type, but not mutant, IGFBP-3 prevented IGF-I from activating the IGF-1 receptor and AKT, and suppressed anchorage-independent cell growth. When xenografted in nude mice, in vivo bioluminescence imaging demonstrated that wild-type, but not mutant IGFBP-3, abrogated tumor formation by the Ras-transformed cells with concurrent induction of apoptosis, implying a prosurvival effect of IGF in cancer cell adaptation to the microenvironment. Moreover, there was more aggressive tumor growth by mutant IGFBP-3 overexpressing cells than control cell tumors, without detectable caspase-3 cleavage in tumor tissues, indicating an IGF-independent growth stimulatory effect of mutant IGFBP-3. In aggregate, these data suggest that IGFBP-3 contributes to esophageal tumor development and progression through IGF-dependent and independent mechanisms.
IGFBP-3; IGF; Ras; esophageal cancer; in vivo bioluminescence
Amyloid-β (Aβ) accumulation in the brain extracellular space is a hallmark of Alzheimer’s disease (AD). The factors regulating this process are only partly understood. Aβ aggregation is a concentration-dependent process that is likely to be dependent on changes in brain interstitial fluid (ISF) levels of Aβ. Using in vivo microdialysis, we found that ISF Aβ levels correlated with wakefulness. ISF Aβ levels also significantly increased during acute sleep deprivation and during orexin infusion, whereas they decreased with infusion of a dual orexin receptor antagonist. Importantly, chronic sleep restriction significantly increased and a dual orexin receptor antagonist decreased Aβ plaque formation in amyloid precursor protein transgenic mice. Thus, the sleep-wake cycle and orexin may play a role in the pathogenesis of AD.
Allergen-induced respiratory inflammation facilitates and/or elicits the extravasation of proinflammatory leukocytes by well understood mechanisms that mediate the movement of multiple cell types. The non-specific character of these pathways led us to hypothesize that circulating cancer cells use similar mechanisms, promoting secondary tumor formation at distal sites. To test this hypothesis, the frequency of metastasis to the lung as a function of allergic pulmonary inflammation was assessed following the intravenous injection of B16-F10 melanoma cells in mice. These studies demonstrated that allergen-induced pulmonary inflammation resulted in a >3-fold increase in lung metastases. This increase was dependent on CD4+ T cell activities; however, it occurred independent of the induced eosinophilia associated with allergen provocation. Interventional strategies showed that existing therapeutic modalities for asthma, such as inhaled corticosteroids, were sufficient to block the enhanced pulmonary recruitment of cancer cells from circulation. Additional mechanistic studies further suggested that the ability of circulating cancer cells to extravasate to surrounding lung tissues was linked to the activation of the vascular endothelium via one or more Gαi-coupled receptors. Interestingly, a survey of a clinical breast cancer surgical database showed that the incidence of asthma was higher among patients with lung metastases. Thus, our data demonstrate that allergic respiratory inflammation may represent a risk factor for the development of lung metastases and suggests that amelioration of the pulmonary inflammation associated with asthma will have a direct and immediate benefit to the 7–8% of breast cancer patients with this lung disease.
Metastasis; Asthma; Endothelial Cell; Diapedesis; Breast Cancer
Discussions of eosinophils are often descriptions of end-stage effector cells with destructive capabilities mediated predominantly by released cytotoxic cationic granule proteins. Moreover, eosinophils in the medical literature are invariably associated with the pathologies linked with helminth infections or allergic diseases such as asthma. This has led to an almost fatalist view of eosinophil effector functions and associated therapeutic strategies targeting these cells that would make even William of Ockham proud - eosinophil effector functions have physiological consequences that increase patient morbidity/mortality and “the only good eosinophils are dead eosinophils”. Unfortunately, the strengths of dogmas are also their greatest weaknesses. Namely, while the repetitive proclamation of dogmatic concepts by authoritative sources (i.e., reviews, meeting proceedings, textbooks, etc.) builds consensus within the medical community and lower the entropies surrounding difficult issues, they often ignore not easily explained details and place diminished importance on alternative hypotheses. The goal of this perspective is two fold: (i) We will review recent observations regarding eosinophils and their activities as well as reinterpret earlier data as part of the synthesis of a new paradigm. In this paradigm, we hypothesize that eosinophils accumulate at unique sites in response to cell turnover or in response to local stem cell activity(ies). We further suggest that this accumulation is part of one or more mechanisms regulating tissue homeostasis. Specifically, instead of immune cells exclusively mediating innate host defense, we suggest that accumulating tissue eosinophils are actually regulators of Local Immunity And/or Remodeling/Repair in both health and disease - The LIAR Hypothesis; (ii) We want to be inflammatory (pun intended!) and challenge the currently common perspective of eosinophils as destructive end-stage effector cells. Our hope is to create more questions than we answer and provoke everyone to spend countless hours simply to prove us wrong!
Remodeling/Repair; Immune Regulation; Tissue Homeostasis; Stem Cells; Effector Function
Protective innate immunity to the nematode Strongyloides stercoralis requires eosinophils in the parasite killing process. Experiments were performed to determine if an extract of S. stercoralis would trigger eosinophil chemotaxis, and to then compare the chemotactic migration response, including second messenger signals and receptors, to those mechanisms triggered by host chemoattractants. Eosinophils undergo both chemotaxis and chemokinesis to soluble parasite extract in transwell plates. Pretreatment of eosinophils with pertussis toxin, a G protein-coupled receptor inhibitor, inhibited migration of the eosinophils to the parasite extract. Likewise, blocking PI3K, tyrosine kinase, p38 and p44/42 inhibited eosinophil chemotaxis to parasite extract. Furthermore, CCR3, CXCR4 or CXCR2 antagonists significantly inhibited eosinophil chemotaxis to the parasite extract. Molecular weight fractionation of parasite extract revealed that molecules attracting eosinophils were present in several fractions, with molecules greater than 30 kDa being the most potent. Treating the extract with proteinase K or chitinase significantly inhibited its ability to induce chemotaxis, thereby demonstrating that the chemoattractants were both protein and chitin. Therefore, chemoattractants derived from parasites and host species stimulate similar receptors and second messenger signals to induce eosinophil chemotaxis. Parasite extract stimulates multiple receptors on the eosinophil surface, which ensures a robust innate immune response to the parasite.
Eosinophil; Chemotaxis; Strongyloides stercoralis; CCR3; CXCR4; CXCR2
Mechanisms underlying esophageal remodeling with subepithelial fibrosis in eosinophilic esophagitis (EoE) have not been delineated.
To explore a role for Epithelial Mesenchymal Transition (EMT) in EoE, and whether EMT resolves with treatment.
Esophageal biopsies from 60 children were immunostained for epithelial (cytokeratin) and mesenchymal (vimentin) EMT biomarkers, and EMT quantified. Subjects studied had EoE (n=17), EoE-indeterminate (n=15), GERD (n=7) or normal esophagus (n=21). EMT was analyzed for relationships to diagnosis, eosinophils, and indices of subepithelial fibrosis, eosinophil peroxidase (EPX) and TGF-β immunostaining. EMT was assessed in pre- and post-treatment biopsies from 18 EoE subjects treated with elemental diet, six-food elimination diet, or topical corticosteroids (n=6/group).
TGF-β1 treatment of esophageal epithelial cells in vitro for 24hrs induced upregulation of mesenchymal genes characteristic of EMT including N-cadherin (3.3-fold), vimentin (2.1-fold) and fibronectin (7.5-fold). EMT in esophageal biopsies was associated with EoE (or indeterminate EoE), but not GERD or normal esophagus, and was correlated to eosinophils (r=0.691), EPX (r=0.738) and TGF-β (r=0.520) immunostaining, and fibrosis (r=0.644) indices. EMT resolved with EoE treatments that induced clinicopathologic remission with reduced eosinophils. EMT decreased significantly post-treatment by 74.1% overall in the 18 treated EoE subjects; pre- vs. post-treatment EMT scores–3.17±0.82 vs. 0.82±0.39 (p<0.001), with similar decreases within treatment groups. Pre-/post-treatment EMT was strongly correlated with eosinophils for combined (r=0.804, p< 0.001) and individual treatment groups.
EMT likely contributes to subepithelial fibrosis in EoE, resolves with treatments that decrease esophageal inflammation, and its resolution correlates with decreased numbers of esophageal eosinophils.
eosinophil; esophagitis; epithelium; remodeling; fibrosis; mesenchymal; vimentin; cytokeratin