Epigenetic regulation of epithelial dectin-1 through an IL-33-STAT3 axis in allergic disease.

Allergic diseases arise in susceptible individuals in part because of decrements in protective pathways. The mechanism by which these anti-inflammatory molecules become repressed remains unclear. We have previously reported that epithelial dectin-1 prevents aberrant type 2 responses and is downregulated in the epithelium of allergic patients. Here, we report that dectin-1 is constitutively expressed by the respiratory epithelium in humans and that IL-33 specifically acts as a repressor of dectin-1. Mechanistically, this occurs via IL-33-dependent STAT3 activation and the subsequent repression of the dectin-1 gene, CLEC7A. We have identified a novel enhancer region upstream of the proximal promoter of CLEC7A that is only accessible in epithelial cells, but not in hematopoietic cells. Epigenetic repression of CLEC7A through this newly identified locus, downstream of an aberrant IL-33-STAT3 axis, occurs in the epithelium of allergic individuals. Collectively, our data identify a mechanism of epigenetic fine-tuning of dectin-1 expression in epithelial cells that may participate in allergenicity.

Interleukin 13 (IL-13) alters hypoxia-associated genes and upregulates CD73.

BACKGROUND: Interleukin 13 (IL-13) is a pleiotropic cytokine that has been shown to be important in the pathogenesis of chronic rhinosinusitis with nasal polyps (CRSwNP) and other type 2 inflammation-related diseases. Increased IL-13 expression can elicit several pro-inflammatory effects, including eosinophilia, and pathology such as increased mucus secretion. Polypogenesis in chronic rhinosinusitis (CRS) can be caused by hypoxia, which can also lead to hyperpermeability of airway epithelium and epithelium-to-mesenchymal translation through the upregulation of hypoxia-associated genes, such as HIF1. Whether T-helper 2 (Th2) inflammatory cytokines, such as IL-13, can also induce sinonasal epithelial hypoxia-associated genes is currently unknown. METHODS: Human air-liquid interface (ALI) sinonasal epithelial cell cultures treated with recombinant IL-13 were analyzed by real-time polymerase chain reaction (PCR) and flow cytometry to determine the effect on epithelial cells. RESULTS: Whole tissue from CRSwNP subjects showed increased HIF1A gene expression. Treatment of fully differentiated human ALI cultures with IL-13 resulted in a concurrent increase in HIF1A and ARNT messenger RNA (mRNA) expression. However, the level of EPAS1 expression was significantly reduced. IL-13 also had a dose-dependent response on the expression of HIF genes and the time course experiment showed peak expression of HIF1A and ARNT at 5 to 7 days poststimulation. Remarkably, CD73 surface expression also peaked at day 5 poststimulation. CONCLUSION: Our data suggests that IL-13 can induce hypoxia signaling pathway genes leading to surface expression of CD73, which has an anti-inflammatory effect.

Nasal polyp fibroblasts modulate epithelial characteristics via Wnt signaling.

BACKGROUND: While essential to the normal differentiation of ciliated airway epithelial cells, upregulated Wnt signaling in chronic rhinosinusitis with nasal polyps (CRSwNP) has been proposed to result in abnormal epithelial morphology and dysfunctional mucociliary clearance. The mechanism of epithelial Wnt signaling dysregulation in CRSwNP is unknown, and importantly cellular sources of Wnt ligands in CRSwNP have not yet been investigated. METHODS: Human sinonasal epithelial cells (hSNECs) and human sinonasal fibroblasts (hSNFs) were collected from 34 human subjects (25 control and 9 CRSwNP) and differentiated as primary air-liquid interface (ALI) and organoid co-cultures. hSNECs were isolated to the apical compartment of the transwell and hSNFs were isolated to the basolateral compartment. After 21 days of ALI culture, ciliary expression and sinonasal epithelial morphology were examined by immunohistochemistry (IHC) and quantitative real-time polymerase chain reaction (qRT-PCR). An organoid model was used to evaluate proliferation of basal cells in presence of hSNFs. RESULTS: Epithelial cells co-cultured with CRSwNP-hSNFs revealed significantly decreased ciliated cells, altered epithelial cell morphology, and increased colony forming efficiency compared to epithelial cells co-cultured with control-hSNFs. CRSwNP-hSNFs showed significantly higher messenger RNA (mRNA) expression of canonical WNT3A. A Wnt agonist, CHIR99021, replicated CRSwNP-hSNF co-cultures, and treatment with the Wnt inhibitor IWP2 prevented abnormal morphologies. CONCLUSION: These results suggest that abnormal interactions between epithelial cells and fibroblasts may contribute to CRSwNP pathogenesis and supports the concept that dysregulated Wnt signaling contributes impairment to epithelial function in CRSwNP.

Unique pulmonary immunotoxicological effects of urban PM are not recapitulated solely by carbon black, diesel exhaust or coal fly ash.

BACKGROUND: Exposure to particulate matter (PM) is increasing worldwide as a result of increased human activity, the rapid industrialization of developing countries, and effects of climate change. Adverse effects of PM on human health are well documented, and because PM exposure occurs mostly through the airways, PM has especially deleterious impact on the lungs. OBJECTIVE: We investigated whether surrogate PM particles like carbon black (CB), diesel exhaust particle (DEP), coal fly ash (CFA) can recapitulate the allergic airway inflammatory response induced by urban particulate matter. METHODS: We compared the pro-inflammatory potential of urban PM collected from New York (NYC) and Baltimore (Balt) with CB, DEP and CFA surrogate PM particles. Eight to ten weeks old BALB/cJ mice were exposed through the airways to particulate material, and markers of airway inflammation were determined. Specifically, we assessed cellular influx, mucus production, lung function, cytokine levels as well as immune cell profiling of the lungs. RESULTS: Herein, we demonstrate that exposure to equivalent mass of stand-alone surrogate PM particles like CB, DEP and CFA, fails to induce significant airway inflammatory response seen after similar exposure to urban PMs. Specifically, we observe that PM collected from New York (NYC) and Baltimore city (Balt) triggers a mixed Th2/Th17 response accompanied by eosinophilic and neutrophilic influx, mucus production and airway hyperresponsiveness (AHR). Although the immune profile of NYC and Baltimore PMs are similar, they demonstrate considerable differences in their potency. Baltimore PM induced more robust airway inflammation, AHR, and Th2 cytokine production, possibly due to the greater metal content in Baltimore PM. CONCLUSIONS: Urban particulate matter with its unique physiochemical properties and heterogeneous composition elicits a mixed Th2/Th17 allergic airway response that is not seen after similar exposures to surrogate PM particles.

A tetravalent alphavirus-vector based dengue vaccine provides effective immunity in an early life mouse model.

Dengue viruses (DENV1-4) cause 390 million clinical infections every year, several hundred thousand of which progress to severe hemorrhagic and shock syndromes. Preexisting immunity resulting from a previous DENV infection is the major risk factor for severe dengue during secondary heterologous infections. During primary infections in infants, maternal antibodies pose an analogous risk. At the same time, maternal antibodies are likely to prevent induction of endogenous anti-DENV antibodies in response to current live, attenuated virus (LAV) vaccine candidates. Any effective early life dengue vaccine has to overcome maternal antibody interference (leading to ineffective vaccination) and poor induction of antibody responses (increasing the risk of severe dengue disease upon primary infection). In a previous study, we demonstrated that a non-propagating Venezuelan equine encephalitis virus replicon expression vector (VRP), expressing the ectodomain of DENV E protein (E85), overcomes maternal interference in a BALB/c mouse model. We report here that a single immunization with a tetravalent VRP vaccine induced NAb and T-cell responses to each serotype at a level equivalent to the monovalent vaccine components, suggesting that this vaccine modality can overcome serotype interference. Furthermore, neonatal immunization was durable and could be boosted later in life to further increase NAb and T-cell responses. Although the neonatal immune response was lower in magnitude than responses in adult BALB/c mice, we demonstrate that VRP vaccines generated protective immunity from a lethal challenge after a single neonatal immunization. In summary, VRP vaccines expressing DENV antigens were immunogenic and protective in neonates, and hence are promising candidates for safe and effective vaccination in early life.

An alphavirus-based adjuvant enhances serum and mucosal antibodies, T cells, and protective immunity to influenza virus in neonatal mice.

UNLABELLED: Neonatal immune responses to infection and vaccination are biased toward TH2 at the cost of proinflammatory TH1 responses needed to combat intracellular pathogens. However, upon appropriate stimulation, the neonatal immune system can induce adult-like TH1 responses. Here we report that a new class of vaccine adjuvant is especially well suited to enhance early life immunity. The GVI3000 adjuvant is a safe, nonpropagating, truncated derivative of Venezuelan equine encephalitis virus that targets dendritic cells (DCs) in the draining lymph node (DLN) and produces intracellular viral RNA without propagating to other cells. RNA synthesis strongly activates the innate immune response so that in adult animals, codelivery of soluble protein antigens induces robust humoral, cellular, and mucosal responses. The adjuvant properties of GVI3000 were tested in a neonatal BALB/c mouse model using inactivated influenza virus (iFlu). After a single immunization, mice immunized with iFlu with the GVI3000 adjuvant (GVI3000-adjuvanted iFlu) had significantly higher and sustained influenza virus-specific IgG antibodies, mainly IgG2a (TH1), compared to the mice immunized with antigen only. GVI3000 significantly increased antigen-specific CD4(+) and CD8(+) T cells, primed mucosal immune responses, and enhanced protection from lethal challenge. As seen in adult mice, the GVI3000 adjuvant increased the DC population in the DLNs, caused activation and maturation of DCs, and induced proinflammatory cytokines and chemokines in the DLNs soon after immunization, including gamma interferon (IFN-γ), tumor necrosis factor alpha (TNF-α), granulocyte colony-stimulating factor (G-CSF), and interleukin 6 (IL-6). In summary, the GVI3000 adjuvant induced an adult-like adjuvant effect with an influenza vaccine and has the potential to improve the immunogenicity and protective efficacy of new and existing neonatal vaccines. IMPORTANCE: The suboptimal immune responses in early life constitute a significant challenge for vaccine design. Here we report that a new class of adjuvant is safe and effective for early life immunization and demonstrate its ability to significantly improve the protective efficacy of an inactivated influenza virus vaccine in a neonatal mouse model. The GVI3000 adjuvant delivers a truncated, self-replicating viral RNA into dendritic cells in the draining lymph node. Intracellular RNA replication activates a strong innate immune response that significantly enhances adaptive antibody and cellular immune responses to codelivered antigens. A significant increase in protection results from a single immunization. Importantly, this adjuvant also primed a mucosal IgA response, which is likely to be critical for protection during many early life infections.

Measurements of vascular function using strain-gauge plethysmography: technical considerations, standardization, and physiological findings.

The main purpose of the present study was to examine the relationships between measures of fitness [estimated peak oxygen consumption (V(O2) peak) and handgrip strength] and forearm vascular function in 55 young (22.6 +/- 3.5 yr) adults. In addition, the present study considered methodological and technical aspects regarding the examination of the venous system using mercury in-Silastic strain-gauge plethysmography (MSGP). Forearm venous capacitance and outflow were examined using five different [7, 14, 21, 28, and 35 mmHg < diastolic blood pressure (DBP)] venous occlusion pressures and after a 5- and 10-min period of venous occlusion. A pressure of 7 mmHg < DBP and a period of 10 min venous occlusion produced the greatest (P < 0.05) venous capacitance and outflow, without altering arterial indexes. Reproducibility of forearm arterial and venous indexes were evaluated at rest and after 5 min of upper arm arterial occlusion at 240 mmHg on three different occasions within 10 days with the interclass correlation coefficient ranging from 0.70 and 0.94. Estimated V(O2) peak correlated with postocclusion arterial inflow (r = 0.54, P = 0.012) and resting venous outflow (r = 0.56, P = 0.016). Finally, handgrip strength was associated with venous capacitance (r = 0.57, P = 0.007) and outflow (r = 0.67, P = 0.001). These results indicate that the examination of forearm vascular function using MSGP is reproducible. Moreover, the data show the importance of careful consideration of the selection of venous occlusion pressure and period when implementing these measures in longitudinal trials. Finally, the associations between fitness and venous measures suggest a link between venous function and exercise performance.