Group 2 innate lymphoid cells are critical for the initiation of adaptive T helper 2 cell-mediated allergic lung inflammation.

Naive CD4(+) T cell differentiation into distinct subsets of T helper (Th) cells is a pivotal process in the initiation of the adaptive immune response. Allergens predominantly stimulate Th2 cells, causing allergic inflammation. However, why allergens induce Th2 cell differentiation is not well understood. Here we show that group 2 innate lymphoid cells (ILC2s) are required to mount a robust Th2 cell response to the protease-allergen papain. Intranasal administration of papain stimulated ILC2s and Th2 cells, causing allergic lung inflammation and elevated immunoglobulin E titers. This process was severely impaired in ILC2-deficient mice. Whereas interleukin-4 (IL-4) was dispensable for papain-induced Th2 cell differentiation, ILC2-derived IL-13 was critical as it promoted migration of activated lung dendritic cells into the draining lymph node where they primed naive T cells to differentiate into Th2 cells. Papain-induced ILC2 activation and Th2 cell differentiation was IL-33-dependent, suggesting a common pathway in the initiation of Th2 cell responses to allergen.

Retinoic-acid-receptor-related orphan nuclear receptor alpha is required for natural helper cell development and allergic inflammation.

Natural helper (NH) cells are innate lymphoid cells (ILCs) that produce T helper-2 (Th2)-cell-type cytokines in the lung- and gut-associated lymphoid tissues. Currently, the lineage relationship between NH cells in different tissues and between NH cells and interleukin-22 (IL-22)-producing retinoic-acid-receptor-related orphan receptor (ROR)γt-positive ILCs is unclear. Here, we report that NH cells express RORα, but not RORγt. RORα-deficient, but not RORγt-deficient, mice lacked NH cells in all tissues, whereas all other lymphocytes, including RORγt(+) ILCs, were unaffected. NH-cell-deficient mice generated by RORα-deficient bone-marrow transplantation had normal Th2 cell responses but failed to develop acute lung inflammation in response to protease allergen, thus confirming the essential role of NH cells in allergic lung inflammation. We have also identified RORα-dependent NH cell progenitors in the bone marrow. Thus, all NH cells belong to a unique RORα-dependent cell lineage separate from other lymphoid cell lineages.

Loss of Vascular CD34 Results in Increased Sensitivity to Lung Injury.

Survival during lung injury requires a coordinated program of damage limitation and rapid repair. CD34 is a cell surface sialomucin expressed by epithelial, vascular, and stromal cells that promotes cell adhesion, coordinates inflammatory cell recruitment, and drives angiogenesis. To test whether CD34 also orchestrates pulmonary damage and repair, we induced acute lung injury in wild-type (WT) and Cd34-/- mice by bleomycin administration. We found that Cd34-/- mice displayed severe weight loss and early mortality compared with WT controls. Despite equivalent early airway inflammation to WT mice, CD34-deficient animals developed interstitial edema and endothelial delamination, suggesting impaired endothelial function. Chimeric Cd34-/- mice reconstituted with WT hematopoietic cells exhibited early mortality compared with WT mice reconstituted with Cd34-/- cells, supporting an endothelial defect. CD34-deficient mice were also more sensitive to lung damage caused by influenza infection, showing greater weight loss and more extensive pulmonary remodeling. Together, our data suggest that CD34 plays an essential role in maintaining vascular integrity in the lung in response to chemical- and infection-induced tissue damage.

Dendritic-cell expression of Ship1 regulates Th2 immunity to helminth infection in mice.

In mouse models of infection with the gastrointestinal parasite Trichuris muris, appropriate dendritic-cell (DC) Ag sampling, migration, and presentation to T cells are necessary to mount a protective Th2-polarized adaptive immune response, which is needed to clear infection. SH2-containing inositol 5'-phosphatase 1 (SHIP-1) has been shown to be an important regulator of DC function in vitro through the negative regulation of the phosphoinositide 3-kinase (PI3K) pathway, but its role in vivo is relatively unexplored. In the current work, mice with a specific deletion of SHIP-1 in DCs (Ship1(ΔDC) ) were infected with the parasite T. muris. Ship1(ΔDC) mice were susceptible to infection due to ineffective priming of Th2-polarized responses. This is likely due to an increased production of interleukin (IL) 12p40 by SHIP-1-deficient DCs, as in vivo antibody blockade of IL-12p40 was able to facilitate the clearing of infection in Ship1(ΔDC) mice. Our results describe a critical role for SHIP-1 in regulating the ability of DCs to efficiently prime Th2-type responses.

Enhancing Diagnostic Performance of Symptom-Based Criteria for Irritable Bowel Syndrome by Additional History and Limited Diagnostic Evaluation.

OBJECTIVES: Symptom-based criteria to diagnose irritable bowel syndrome (IBS) positively perform only modestly. Our aim was to assess whether including other items from the clinical history and limited diagnostic evaluation improves their performance. METHODS: We collected complete symptom, colonoscopy, and histology data from 318 consecutive, unselected adult patients with lower gastrointestinal (GI) symptoms in secondary care. All participants underwent colonoscopy, with relevant organic findings recorded. The reference standard used to define the presence of true IBS was patient-reported lower abdominal pain or discomfort associated with a change in bowel habit, in the absence of organic GI disease. Sensitivity, specificity, and positive and negative likelihood ratios (LRs), with 95% confidence intervals, were calculated for Rome III criteria, as well as for modifications, incorporating nocturnal stools, results of simple blood tests (hemoglobin and C-reactive protein (CRP)), measures of somatization, and/or affective disorders (hospital anxiety or depression scale (HADS) score). RESULTS: The sensitivity and specificity of the Rome III criteria for identifying IBS was 69.6%, and 82.0%, respectively, with positive and negative LRs of 3.87 and 0.37, respectively. Clinically useful enhancements in positive LRs were provided by combining Rome III criteria with: (a) high level of somatization (7.27); (b) normal hemoglobin and CRP with HADS score of ≥8 (5.04); (c) normal hemoglobin and CRP with a high level of somatization (7.56); or (d) no nocturnal passage of stool with a high level of somatization (17.3). Specificity was ≥95% with each of these modifications. CONCLUSIONS: Incorporating nocturnal stools, somatization, and affective disorders from the clinical history, and hemoglobin and CRP measurements, enhances the positive LR and specificity of symptom-based Rome III criteria for IBS.

Validation and modification of a diagnostic scoring system to predict microscopic colitis.

OBJECTIVE: Many patients with diarrhoea undergo colonoscopy. If this is macroscopically normal, random biopsies are obtained to rule out microscopic colitis (MC), but most patients have functional disease. Accurate predictors of MC could avoid the need to take biopsies in a substantial proportion of patients, saving money for the health service. We validated a previously described diagnostic scoring system for MC, and incorporated further variables to assess whether this improved performance. MATERIAL AND METHODS: Consecutive adults with loose stools undergoing colonoscopy in Leeds, UK were included. Demographic and symptom data were collected prospectively. The diagnostic scoring system described previously was applied. In addition, the incorporation of further variables, including drugs associated with MC, number of stools, nocturnal passage of stools, and duration of loose stools, into the scoring system was assessed. Sensitivities, specificities, and positive and negative predictive values were calculated. RESULTS: Among 242 patients (mean age 51.0 years, 163 (67.4%) female), 26 (10.7%) of whom had MC, a cut off of ≥4 on the original scoring system had a sensitivity of 92.3% and specificity of 35.2%. Nocturnal passage of stools and duration of loose stools <6 months were significant predictors of MC. Incorporating these variables in a new scoring system with a cut off of ≥6 identified MC with 95.7% sensitivity and 46.0% specificity. CONCLUSIONS: Incorporating nocturnal passage of stools and duration of loose stools into the scoring system may improve ability to predict MC, and avoid random colonic biopsies in a greater proportion of patients with loose stools.

Lineage-specific regulation of allergic airway inflammation by the lipid phosphatase Src homology 2 domain-containing inositol 5-phosphatase (SHIP-1).

BACKGROUND: Inpp5d (Src homology 2 domain-containing inositol-5-phosphatase [Ship1])-deficient mice experience spontaneous airway inflammation and have enhanced sensitivity to allergen-induced airway inflammation. OBJECTIVE: We hypothesized that lineage-specific deletion of Ship1 expression in cells known to be crucial for adaptive TH2 responses would uncover distinct roles that could either positively or negatively regulate susceptibility to allergic airway inflammation (AAI). METHODS: Ship1 expression was deleted in B cells, T cells, or dendritic cells (DCs), and the resulting Ship1(ΔB cell), Ship1(ΔT cell), Ship1(ΔDC), or Ship1(F/F) (wild-type) control mice were evaluated in a model of house dust mite (HDM)-induced AAI. RESULTS: Unlike germline panhematopoietic Ship1 deletion, deletion of Ship1 selectively in either the B-cell, T-cell, or DC lineages did not result in spontaneous airway inflammation. Strikingly, although loss of Ship1 in the B-cell lineage did not affect HDM-induced AAI, loss of Ship1 in either of the T-cell or DC lineages protected mice from AAI by skewing the typical TH2 immune response toward a TH1 response. CONCLUSIONS: Although panhematopoietic deletion of Ship1 leads to spontaneous lung inflammation, selective deletion of Ship1 in T cells or DCs impairs the formation of an adaptive TH2 response and protects animals from HDM-induced AAI.

Perinatal antibiotic-induced shifts in gut microbiota have differential effects on inflammatory lung diseases.

BACKGROUND: Resident gut microbiota are now recognized as potent modifiers of host immune responses in various scenarios. Recently, we demonstrated that perinatal exposure to vancomycin, but not streptomycin, profoundly alters gut microbiota and enhances susceptibility to a TH2 model of allergic asthma. OBJECTIVE: Here we sought to further clarify the etiology of these changes by determining whether perinatal antibiotic treatment has a similar effect on the TH1/TH17-mediated lung disease, hypersensitivity pneumonitis. METHODS: Hypersensitivity pneumonitis was induced in C57BL/6 wild-type or recombination-activating gene 1-deficient mice treated perinatally with vancomycin or streptomycin by repeated intranasal administration of Saccharopolyspora rectivirgula antigen. Disease severity was assessed by measuring lung inflammation, pathology, cytokine responses, and serum antibodies. Microbial community analyses were performed on stool samples via 16S ribosomal RNA pyrosequencing and correlations between disease severity and specific bacterial taxa were identified. RESULTS: Surprisingly, in contrast to our findings in an allergic asthma model, we found that the severity of hypersensitivity pneumonitis was unaffected by vancomycin, but increased dramatically after streptomycin treatment. This likely reflects an effect on the adaptive, rather than innate, immune response because the effects of streptomycin were not observed during the early phases of disease and were abrogated in recombination-activating gene 1-deficient mice. Interestingly, Bacteroidetes dominated the intestinal microbiota of streptomycin-treated animals, while vancomycin promoted the expansion of the Firmicutes. CONCLUSIONS: Perinatal antibiotics exert highly selective effects on resident gut flora, which, in turn, lead to very specific alterations in susceptibility to TH2- or TH1/TH17-driven lung inflammatory disease.

The nucleotide-binding domain, leucine-rich repeat protein 3 inflammasome/IL-1 receptor I axis mediates innate, but not adaptive, immune responses after exposure to particulate matter under 10 µm.

Exposure to particulate matter (PM), a major component of air pollution, contributes to increased morbidity and mortality worldwide. Inhaled PM induces innate immune responses by airway epithelial cells that may lead to the exacerbation or de novo development of airway disease. We have previously shown that 10-µm PM (PM10) activates the nucleotide-binding domain, leucine-rich repeat protein (NLRP) 3 inflammasome in human airway epithelial cells. Our objective was to determine the innate and adaptive immune responses mediated by the airway epithelium NLRP3 inflammasome in response to PM10 exposure. Using in vitro cultures of human airway epithelial cells and in vivo studies with wild-type and Nlrp3(-/-) mice, we investigated the downstream consequences of PM10-induced NLPR3 inflammasome activation on cytokine production, cellular inflammation, dendritic cell activation, and PM10-facilitated allergic sensitization. PM10 activates an NLRP3 inflammasome/IL-1 receptor I (IL-1RI) axis in airway epithelial cells, resulting in IL-1ß, CC chemokine ligand-20, and granulocyte/macrophage colony-stimulating factor production, which is associated with dendritic cell activation and lung neutrophilia. Despite these profound innate immune responses in the airway epithelium, the NLRP3 inflammasome/IL-1RI axis is dispensable for PM10-facilitated allergic sensitization. We demonstrate the importance of the lung NLRP3 inflammasome in mediating PM10 exposure-associated innate, but not adaptive, immune responses. Our study highlights a mechanism by which PM10 exposure can contribute to the exacerbation of airway disease, but not PM10-facilitated allergic sensitization.

Pulmonary CD103 expression regulates airway inflammation in asthma.

Although CD103(+) cells recently emerged as key regulatory cells in the gut, the role of CD103 ubiquitous expression in the lung and development of allergic airway disease has never been studied. To answer this important question, we evaluated the response of Cd103(-/-) mice in two separate well-described mouse models of asthma (ovalbumin and house dust mite extract). Pulmonary inflammation was assessed by analysis of bronchoalveolar lavage content, histology, and cytokine response. CD103 expression was analyzed on lung dendritic cells and T cell subsets by flow cytometry. Cd103(-/-) mice exposed to antigens developed exacerbated lung inflammation, characterized by increased eosinophilic infiltration, severe tissue inflammation, and altered cytokine response. In wild-type mice exposed to house dust mite, CD103(+) dendritic cells are increased in the lung and an important subset of CD4(+) T cells, CD8(+) T cells, and T regulatory cells express CD103. Importantly, Cd103(-/-) mice presented a deficiency in the resolution phase of inflammation, which supports an important role for this molecule in the control of inflammation severity. These results suggest an important role for CD103 in the control of airway inflammation in asthma.

Group 2 innate lymphoid cells facilitate sensitization to local, but not systemic, TH2-inducing allergen exposures.

BACKGROUND: Allergic inflammation involves the sensitization of naive CD4(+) T cells to allergens, resulting in a TH2-skewed inflammatory response. Although antigen presentation by dendritic cells to T cells in the lymph node is crucial for TH2 cell development, the innate signals that initiate adaptive type 2 inflammation and the role of group 2 innate lymphoid cells (ILC2s) are poorly understood. OBJECTIVE: We sought to investigate the influence of ILC2s and the route of priming on the development of an adaptive type 2 immune response to lung allergens. METHODS: Wild-type and ILC2-deficient mice were exposed intranasally or systemically to the TH2-inducing antigens house dust mite or ovalbumin in a model of allergic airway inflammation or the TH17-inducing bacterial antigen Saccharopolyspora rectivirgula in a model of hypersensitivity pneumonitis. The formation of an adaptive immune response was evaluated based on serum antibody titers and production of T cell-derived cytokines (IL-4, IL-5, IL-13 and IL-17A). RESULTS: We find that lung ILC2s play a critical role in priming the adaptive type 2 immune response to inhaled allergens, including the recruitment of eosinophils, TH2 cytokine production and serum IgE levels. Surprisingly, systemic priming with ovalbumin, with or without adjuvants, circumvents the requirement for ILC2s in inducing TH2-driven lung inflammation. ILC2s were also found to be dispensable for the sensitization to TH1- or TH17-inducing antigens. CONCLUSION: These data highlight a critical role for ILC2s in the development of adaptive type 2 responses to local, but not systemic, antigen exposure.

Early life antibiotic-driven changes in microbiota enhance susceptibility to allergic asthma.

Allergic asthma rates have increased steadily in developed countries, arguing for an environmental aetiology. To assess the influence of gut microbiota on experimental murine allergic asthma, we treated neonatal mice with clinical doses of two widely used antibiotics--streptomycin and vancomycin--and evaluated resulting shifts in resident flora and subsequent susceptibility to allergic asthma. Streptomycin treatment had little effect on the microbiota and on disease, whereas vancomycin reduced microbial diversity, shifted the composition of the bacterial population and enhanced disease severity. Neither antibiotic had a significant effect when administered to adult mice. Consistent with the 'hygiene hypothesis', our data support a neonatal, microbiota-driven, specific increase in susceptibility to experimental murine allergic asthma.

CD34 is required for dendritic cell trafficking and pathology in murine hypersensitivity pneumonitis.

RATIONALE: Although recent work has shown that CD34 plays an important role in the trafficking of inflammatory cells during Th2-biased inflammatory responses, its role in Th1/Th17-biased disease as well as dendritic cell (DC) trafficking is unknown. OBJECTIVES: We used CD34-deficient mice (Cd34(-/-)) to investigate the role of CD34 in the Th1/Th17-biased lung inflammatory disease, hypersensitivity pneumonitis (HP). METHODS: HP was induced in wild-type (wt) and Cd34(-/-) mice by repeated intranasal administration of Saccharopolyspora rectivirgula antigen. Lung inflammation was assessed by histology and analysis of bronchoalveolar lavage cells. Primary and secondary immune responses were evaluated by cytokine recall responses of pulmonary inflammatory cells as well as draining lymph node cells. MEASUREMENTS AND MAIN RESULTS: Cd34(-/-) mice were highly resistant to the development of HP and exhibited an inflammatory pattern more reflective of a primary response to S. rectivirgula rather than the chronic lymphocytosis that is typical of this disease. Cytokine recall responses from Cd34(-/-) lymph node cells were dampened and consistent with a failure of antigen-loaded Cd34(-/-) DCs to deliver antigen and prime T cells in the draining lymph nodes. In agreement with this interpretation, adoptive transfer of wt DCs into Cd34(-/-) mice was sufficient to restore normal sensitivity to HP. CD34 was found to be expressed by wt DCs, and Cd34(-/-) DCs exhibited an impaired ability to chemotax toward a subset of chemokines in vitro. Finally, expression of human CD34 in Cd34(-/-) mice restored normal susceptibility to HP. CONCLUSIONS: We conclude that CD34 is expressed by mucosal DCs and plays an important role in their trafficking through the lung and to the lymph nodes. Our data also suggest that CD34 may play a selective role in the efficient migration of these cells to a subset of chemokines.

IL-7Rα and L-selectin, but not CD103 or CD34, are required for murine peanut-induced anaphylaxis.

BACKGROUND: Allergy to peanuts results in severe anaphylactic responses in affected individuals, and has dramatic effects on society and public policy. Despite the health impacts of peanut-induced anaphylaxis (PIA), relatively little is known about immune mechanisms underlying the disease. Using a mouse model of PIA, we evaluated mice with deletions in four distinct immune molecules (IL7Rα, L-selectin, CD34, CD103), for perturbed responses. METHODS: PIA was induced by intragastric sensitization with peanut antigen and cholera toxin adjuvant, followed by intraperitoneal challenge with crude peanut extract (CPE). Disease outcome was assessed by monitoring body temperature, clinical symptoms, and serum histamine levels. Resistant mice were evaluated for total and antigen specific serum IgE, as well as susceptibility to passive systemic anaphylaxis. RESULTS: PIA responses were dramatically reduced in IL7Rα-/- and L-selectin-/- mice, despite normal peanut-specific IgE production and susceptibility to passive systemic anaphylaxis. In contrast, CD34-/- and CD103-/- mice exhibited robust PIA responses, indistinguishable from wild type controls. CONCLUSIONS: Loss of L-selectin or IL7Rα function is sufficient to impair PIA, while CD34 or CD103 ablation has no effect on disease severity. More broadly, our findings suggest that future food allergy interventions should focus on disrupting sensitization to food allergens and limiting antigen-specific late-phase responses. Conversely, therapies targeting immune cell migration following antigen challenge are unlikely to have significant benefits, particularly considering the rapid kinetics of PIA.

Overproduction of IFNγ by Cbl-b-Deficient CD8+ T Cells Provides Resistance against Regulatory T Cells and Induces Potent Antitumor Immunity.

Regulatory T cells (Treg) are an integral component of the adaptive immune system that negatively affect antitumor immunity. Here, we investigated the role of the E3 ubiquitin ligase casitas B-lineage lymphoma-b (Cbl-b) in establishing CD8+ T-cell resistance to Treg-mediated suppression to enhance antitumor immunity. Transcriptomic analyses suggested that Cbl-b regulates pathways associated with cytokine signaling and cellular proliferation. We showed that the hypersecretion of IFNγ by Cbl-b-deficient CD8+ T cells selectively attenuated CD8+ T-cell suppression by Tregs. Although IFNγ production by Cbl-b-deficient T cells contributed to phenotypic alterations in Tregs, the cytokine did not attenuate the suppressive function of Tregs. Instead, IFNγ had a profound effect on CD8+ T cells by directly upregulating interferon-stimulated genes and modulating T-cell activation. In murine models of adoptive T-cell therapy, Cbl-b-deficient T cells elicited superior antitumor immune response. Furthermore, Cbl-b-deficient CD8+ T cells were less susceptible to suppression by Tregs in the tumor through the effects of IFNγ. Collectively, this study demonstrates that the hypersecretion of IFNγ serves as a key mechanism by which Cbl-b-deficient CD8+ T cells are rendered resistant to Tregs. See related Spotlight by Wolf and Baier, p. 370.

Mechanical Stiffness Controls Dendritic Cell Metabolism and Function.

Stiffness in the tissue microenvironment changes in most diseases and immunological conditions, but its direct influence on the immune system is poorly understood. Here, we show that static tension impacts immune cell function, maturation, and metabolism. Bone-marrow-derived and/or splenic dendritic cells (DCs) grown in vitro at physiological resting stiffness have reduced proliferation, activation, and cytokine production compared with cells grown under higher stiffness, mimicking fibro-inflammatory disease. Consistently, DCs grown under higher stiffness show increased activation and flux of major glucose metabolic pathways. In DC models of autoimmune diabetes and tumor immunotherapy, tension primes DCs to elicit an adaptive immune response. Mechanistic workup identifies the Hippo-signaling molecule, TAZ, as well as Ca2+-related ion channels, including potentially PIEZO1, as important effectors impacting DC metabolism and function under tension. Tension also directs the phenotypes of monocyte-derived DCs in humans. Thus, mechanical stiffness is a critical environmental cue of DCs and innate immunity.

Coenzyme A fuels T cell anti-tumor immunity.

Metabolic programming is intricately linked to the anti-tumor properties of T cells. To study the metabolic pathways associated with increased anti-tumor T cell function, we utilized a metabolomics approach to characterize three different CD8+ T cell subsets with varying degrees of anti-tumor activity in murine models, of which IL-22-producing Tc22 cells displayed the most robust anti-tumor activity. Tc22s demonstrated upregulation of the pantothenate/coenzyme A (CoA) pathway and a requirement for oxidative phosphorylation (OXPHOS) for differentiation. Exogenous administration of CoA reprogrammed T cells to increase OXPHOS and adopt the CD8+ Tc22 phenotype independent of polarizing conditions via the transcription factors HIF-1α and the aryl hydrocarbon receptor (AhR). In murine tumor models, treatment of mice with the CoA precursor pantothenate enhanced the efficacy of anti-PDL1 antibody therapy. In patients with melanoma, pre-treatment plasma pantothenic acid levels were positively correlated with the response to anti-PD1 therapy. Collectively, our data demonstrate that pantothenate and its metabolite CoA drive T cell polarization, bioenergetics, and anti-tumor immunity.

Hypoxia-inducible factor 1 alpha limits dendritic cell stimulation of CD8 T cell immunity.

Dendritic cells are sentinels of the immune system and represent a key cell in the activation of the adaptive immune response. Hypoxia-inducible factor 1 alpha (HIF-1α)-a crucial oxygen sensor stabilized during hypoxic conditions-has been shown to have both activating and inhibitory effects in immune cells in a context- and cell-dependent manner. Previous studies have demonstrated that in some immune cell types, HIF-1α serves a pro-inflammatory role. Genetic deletion of HIF-1α in macrophages has been reported to reduce their pro-inflammatory function. In contrast, loss of HIF-1α enhanced the pro-inflammatory activity of dendritic cells in a bacterial infection model. In this study, we aimed to further clarify the effects of HIF-1α in dendritic cells. Constitutive expression of HIF-1α resulted in diminished immunostimulatory capacity of dendritic cells in vivo, while conditional deletion of HIF-1α in dendritic cells enhanced their ability to induce a cytotoxic T cell response. HIF-1α-expressing dendritic cells demonstrated increased production of inhibitory mediators including IL-10, iNOS and VEGF, which correlated with their reduced capacity to drive effector CD8+ T cell function. Altogether, these data reveal that HIF-1α can promote the anti-inflammatory functions of dendritic cells and provides insight into dysfunctional immune responses in the context of HIF-1α activation.

Radiation and Heat Improve the Delivery and Efficacy of Nanotherapeutics by Modulating Intratumoral Fluid Dynamics.

Nanomedicine drug delivery systems are capable of transporting significant payloads to solid tumors. However, only a modest increase in antitumor efficacy relative to the standard of care has been observed. In this study, we demonstrate that a single dose of radiation or mild hyperthermia can substantially improve tumor uptake and distribution of nanotherapeutics, resulting in improved treatment efficacy. The delivery of nanomedicine was driven by a reduction in interstitial fluid pressure (IFP) and small perturbation of steady-state fluid flow. The transient effects on fluid dynamics in tumors with high IFP was also shown to dominate over immune cell endocytic capacity, another mechanism suspected of improving drug delivery. Furthermore, we demonstrate the specificity of this mechanism by showing that delivery of nanotherapeutics to low IFP tumors with high leukocyte infiltration does not benefit from pretreatment with radiation or heat. These results demonstrate that focusing on small perturbations to steady-state fluid dynamics, rather than large sustained effects or uncertain immune cell recruitment strategies, can impart a vulnerability to tumors with high IFP and enhance nanotherapeutic drug delivery and treatment efficacy.

Methanosphaera stadtmanae induces a type IV hypersensitivity response in a mouse model of airway inflammation.

Despite improved awareness of work-related diseases and preventive measures, many workers are still at high risk of developing occupational hypersensitivity airway diseases. This stems from a lack of knowledge of bioaerosol composition and their potential effects on human health. Recently, archaea species were identified in bioaerosols, raising the possibility that they play a major role in exposure-related pathology. Specifically, Methanosphaera stadtmanae (MSS) and Methanobrevibacter smithii (MBS) are found in high concentrations in agricultural environments and respiratory exposure to crude extract demonstrates immunomodulatory activity in mice. Nevertheless, our knowledge of the specific impact of methanogens exposure on airway immunity and their potential to induce airway hypersensitivity responses in workers remains scant. Analysis of the lung mucosal response to methanogen crude extracts in mice demonstrated that MSS and MBS predominantly induced TH17 airway inflammation, typical of a type IV hypersensitivity response. Furthermore, the response to MSS was associated with antigen-specific IgG1 and IgG2a production. However, despite the presence of eosinophils after MSS exposure, only a weak TH2 response and no airway hyperresponsiveness were observed. Finally, using eosinophil and mast cell-deficient mice, we confirmed that these cells are dispensable for the TH17 response to MSS, although eosinophils likely contribute to the exacerbation of inflammatory processes induced by MSS crude extract exposure. We conclude that, as MSS induces a clear type IV hypersensitivity lung response, it has the potential to be harmful to workers frequently exposed to this methanogen, and that preventive measures should be taken to avoid chronic hypersensitivity disease development in workers.