IL-1α Signaling Is Critical for Leukocyte Recruitment after Pulmonary Aspergillus fumigatus Challenge

Aspergillus fumigatus is a mold that causes severe pulmonary infections. Our knowledge of how A. fumigatus growth is controlled in the respiratory tract is developing, but still limited. Alveolar macrophages, lung resident macrophages, and airway epithelial cells constitute the first lines of defense against inhaled A. fumigatus conidia. Subsequently, neutrophils and inflammatory CCR2+ monocytes are recruited to the respiratory tract to prevent fungal growth. However, the mechanism of neutrophil and macrophage recruitment to the respiratory tract after A. fumigatus exposure remains an area of ongoing investigation. Here we show that A. fumigatus pulmonary challenge induces expression of the inflammasome-dependent cytokines IL-1β and IL-18 within the first 12 hours, while IL-1α expression continually increases over at least the first 48 hours. Strikingly, Il1r1-deficient mice are highly susceptible to pulmonary A. fumigatus challenge exemplified by robust fungal proliferation in the lung parenchyma. Enhanced susceptibility of Il1r1-deficient mice correlated with defects in leukocyte recruitment and anti-fungal activity. Importantly, IL-1α rather than IL-1β was crucial for optimal leukocyte recruitment. IL-1α signaling enhanced the production of CXCL1. Moreover, CCR2+ monocytes are required for optimal early IL-1α and CXCL1 expression in the lungs, as selective depletion of these cells resulted in their diminished expression, which in turn regulated the early accumulation of neutrophils in the lung after A. fumigatus challenge. Enhancement of pulmonary neutrophil recruitment and anti-fungal activity by CXCL1 treatment could limit fungal growth in the absence of IL-1α signaling. In contrast to the role of IL-1α in neutrophil recruitment, the inflammasome and IL-1β were only essential for optimal activation of anti-fungal activity of macrophages. As such, Pycard-deficient mice are mildly susceptible to A. fumigatus infection. Taken together, our data reveal central, non-redundant roles for IL-1α and IL-1β in controlling A. fumigatus infection in the murine lung

Genre, Methodology and Feminist Practice

The rainy season is not quite over although it has nearly spent itself. I drive leisurely along five miles of roller coaster highway, down and up, up and down again as I drink in the grandeur of the sunset. I come to the 'big hill', around and over which the road twines narrowly. From its summit I see at my left a deep purple canyon, green at the bottom with irrigated fields. At my right the sun is setting across a wide valley, the shadows replaced by roseate gold interrupted by the white resplendence of chalk cliffs. As if this were not sufficient, a light female rain like that which falls constantly over the home of the Corn gods, drops between me and the sun. I gasp in my inability to comprehend the sight fully as I turn my head forty-five degrees to behold a complete rainbow and behind it the thinnest slice of a new moon. (Gladys Reichard, 1934:122)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68113/2/10.1177_0308275X9301300405.pd

IL-1α Signaling Is Critical for Leukocyte Recruitment after Pulmonary Aspergillus fumigatus Challenge

Aspergillus fumigatus is a mold that causes severe pulmonary infections. Our knowledge of how A. fumigatus growth is controlled in the respiratory tract is developing, but still limited. Alveolar macrophages, lung resident macrophages, and airway epithelial cells constitute the first lines of defense against inhaled A. fumigatus conidia. Subsequently, neutrophils and inflammatory CCR2+ monocytes are recruited to the respiratory tract to prevent fungal growth. However, the mechanism of neutrophil and macrophage recruitment to the respiratory tract after A. fumigatus exposure remains an area of ongoing investigation. Here we show that A. fumigatus pulmonary challenge induces expression of the inflammasome-dependent cytokines IL-1β and IL-18 within the first 12 hours, while IL-1α expression continually increases over at least the first 48 hours. Strikingly, Il1r1-deficient mice are highly susceptible to pulmonary A. fumigatus challenge exemplified by robust fungal proliferation in the lung parenchyma. Enhanced susceptibility of Il1r1-deficient mice correlated with defects in leukocyte recruitment and anti-fungal activity. Importantly, IL-1α rather than IL-1β was crucial for optimal leukocyte recruitment. IL-1α signaling enhanced the production of CXCL1. Moreover, CCR2+ monocytes are required for optimal early IL-1α and CXCL1 expression in the lungs, as selective depletion of these cells resulted in their diminished expression, which in turn regulated the early accumulation of neutrophils in the lung after A. fumigatus challenge. Enhancement of pulmonary neutrophil recruitment and anti-fungal activity by CXCL1 treatment could limit fungal growth in the absence of IL-1α signaling. In contrast to the role of IL-1α in neutrophil recruitment, the inflammasome and IL-1β were only essential for optimal activation of anti-fungal activity of macrophages. As such, Pycard-deficient mice are mildly susceptible to A. fumigatus infection. Taken together, our data reveal central, non-redundant roles for IL-1α and IL-1β in controlling A. fumigatus infection in the murine lung

The pathway to health in all policies through intersectoral collaboration on the health workforce: a scoping review

The health workforce (HWF) is a critical component of the health sector. Intersectoral/multisectoral collaboration and action is foundational to strengthening the HWF, enabling responsiveness to dynamic population health demands, and supporting broader goals around social and economic development—such development underpins the need for health in all policies (HiAP). To identify what can be learned from intersectoral/multisectoral activity for HWF strengthening to advance HiAP, we carried out a scoping review. Our review included both peer-reviewed and grey literature. Search terms encompassed terminology for the HWF, intersectoral/multisectoral activities, and governance or management. We carried out a framework analysis, extracting data around different aspects of HiAP implementation. With the aim of supporting action to advance HiAP, our analysis identified core recommendations for intersectoral/multisectoral collaboration for the HWF, organized as a “pathway to HiAP”. We identified 93 documents—67 (72%) were journal articles and 26 (28%) were grey literature. Documents reflected a wide range of country and regional settings. The majority (80, 86%) were published within the past 10 years, reflecting a growing trend in publications on the topic of intersectoral/multisectoral activity for the HWF. From our review and analysis, we identified five areas in the “pathway to HiAP”: ensure robust coordination and leadership; strengthen governance and policymaking and implementation capacities; develop intersectoral/multisectoral strategies; build intersectoral/multisectoral information systems; and identify transparent, resources financing and investment opportunities. Each has key practical and policy implications. Although we introduce a “pathway”, the relationship between the areas is not linear, rather, they both influence and are influenced by one another, reflecting their shared importance. Underscoring this “pathway” is the shared recognition of the importance of intersectoral/multisectoral activity, shared vision, and political will. Advancing health for all policies—generating evidence about best practice to identify and maximize co-benefits across sectors—is a next milestone

Haplotype-specific expression of exon 10 at the human MAPT locus

Neurofibrillary tangles composed of exon 10+ microtubule associated protein tau (MAPT) deposits are the characteristic feature of the neurodegenerative diseases progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD). PSP, CBD and more recently Alzheimer's disease and Parkinson's disease, are associated with the MAPT H1 haplotype, but the relationship between genotype and disease remains unclear. Here, we investigate the hypothesis that H1 expresses more exon 10+ MAPT mRNA compared to the other haplotype, H2, leading to a greater susceptibility to neurodegeneration in H1 carriers. We performed allele-specific gene expression on two H1/H2 heterozygous human neuronal cell lines, and 14 H1/H2 heterozygous control individual post-mortem brain tissue from two brain regions. In both tissue culture and post-mortem brain tissue, we show that the MAPT H1 haplotype expresses significantly more exon 10+ MAPT mRNA than H2. In post-mortem brain tissue, we show that the total level of MAPT expression from H1 and H2 is not significantly different, but that the H1 chromosome expresses up to 1.43-fold more exon 10+ MAPT mRNA than H2 in the globus pallidus, a brain region highly affected by tauopathy (maximum exon 10+ MAPT H1:H2 transcript ratio = 1.425, SD = 0.205, P &lt; 0.0001), and up to 1.29-fold more exon 10+ MAPT mRNA than H2 in the frontal cortex (maximum exon 10+ MAPT H1:H2 transcript ratio = 1.291, SD = 0.315, P = 0.006). These data may explain the increased susceptibility of H1 carriers to neurodegeneration and suggest a potential mechanism between MAPT genetic variability and the pathogenesis of neurodegenerative disease.</p

<i>Il1r1</i>-deficient mice are highly susceptible to <i>Aspergillus fumigatus</i> infection.

<p>Age-matched C57BL/6 or <i>Il1r1</i>-deficient mice were infected i.t. with 5×10⁷ CEA10 conidia and at indicated time-points, mice were euthanized, BALF collected, and lungs saved for histological analysis. <b>(A)</b> Formalin-fixed lungs were paraffin embedded, sectioned, and stained with H&E (top) or GMS (bottom) for analysis by microscopy. Representative lung sections from C57BL/6 and <i>Il1r1</i>-deficient mice infected with CEA10 for 48 h are shown using either the 4× (left) or 20× (right) objectives. <b>(B)</b><i>A. fumigatus</i> germination rates were assessed over the first 72 h of infection by microscopically counting both the number of conidia and number of germlings in GMS-stained section. <b>(C)</b> Survival of C57BL/6, <i>Pycard</i>^−/−, and <i>Il1r1^−/−</i> mice challenged i.t. with 1.5×10⁷<i>A. fumigatus</i> (CEA10) conidia was then monitored for survival over the first 96 h (Mantel-Cox log-rank test, p = 0.0002). Data are representative of 2 independent experiments at each time point consisting of at least 5 mice per group. <b>(D)</b> Total macrophage (left panel) and neutrophil (right panel) recruitment in the BALF was measured at 12, 24, and 48 h post-infection. Data are representative of at least 2 independent experiments at each time point consisting of 3–5 mice per group. Bar graphs show the group mean ± one SEM. Statistically significant differences were determined using Student’s t-test (*p < 0.05; **p < 0.01).</p

CCR2⁺ monocyte regulate early IL-1α and CXCL1 expression.

<p>C57BL/6 or CCR2-depleter mice were treated i.p. with 250 ng of DT 24 h prior to challenge with 5×10⁷ Af293 conidia. <b>(A)</b> Naïve C57BL/6 or CCR2-depleter mice or C57BL/6 or CCR2-depleter mice challenged eight hours prior were euthanized and the BALF and lung tissue collected for flow cytometric analysis to assess depletion of target cells by DT. Plots are gated on CD45⁺ CD11b⁺ cells and show Ly6c and Ly6g staining, which identify the CCR2⁺ monocytes and neutrophils, respectively. <b>(B)</b> IL-1α and <b>(C)</b> CXCL1 protein levels in the lung parenchyma at 8 h post-challenge with 5×10⁷ conidia of <i>A. fumigatus</i> strain Af293 were measured using ELISA assays. Bar graphs show the group means ± one SEM. <b>(D)</b> Eight hours post-challenge with 5×10⁷ conidia of <i>A. fumigatus</i> strain Af293, neutrophils in the BALF were enumerated. Data are representative <b>(B-C)</b> or pooled <b>(D)</b> from two independent experiments consisting of 4 mice per group. Each symbol represents an individual mouse and the line represents the group mean. Statistically significant differences were determined using a one-way ANOVA with Bonferroni’s post-test compared C57BL/6 mice (*p < 0.05, **p < 0.01).</p

Treatment of <i>Il1r1</i>-deficient mice with CXCL1 partially increases resistance to <i>Aspergillus fumigatus</i> infection.

<p>C57BL/6 mice and <i>Il1r1</i>-deficient mice were challenged i.t. with 5×10⁷ CEA10 conidia. Three hours post-challenge mice were given 0.5 μg CXCL1 i.t. or PBS alone. Twenty-four hours post-infection, mice were euthanized, BALF collected, and lungs saved for histological analysis. <b>(A)</b> Formalin-fixed lungs were paraffin embedded, sectioned and stained with H&E (top) or GMS (bottom) for analysis by microscopy. Representative lung sections from <i>Il1r1</i>-deficient mice challenged with CEA10 for 48 h and treated with either PBS or CXCL1 are shown using either the 4× (left) or 20× (right) objectives. <b>(B)</b><i>A. fumigatus</i> germination rates were assessed at 48 h of infection by microscopically counting both the number of conidia and number of germlings in GMS-stained section. Number of conidia and number of germlings were counted for each GMS-stained section to quantify the percent germination. <b>(C)</b> Macrophage and neutrophil recruitment in <i>Il1r1</i>-deficient mice 24 h post-challenge infected with <i>A. fumigatus</i> treated with PBS or CXCL1 given i.t. was determined via cytospins.<b>(D)</b> Bone marrow neutrophils from C57BL/6 and <i>Il1r1</i>-deficient mice were incubated with CEA10 germlings <i>in vitro</i> at a 10:1 ratio in normoxia for 2 h. The XTT assay was used to determine percent fungal damage. <b>(E)</b> Lung damage and <b>(F)</b> leakage were assessed by measuring LDH and albumin, respectively. Data is representative of at least two independent experiments consisting of three to five mice per group, except for the bone marrow neutrophil anti-hyphal XTT assay which is a single experiment which consisted of pooled bone marrow neutrophils from three mice done in triplicate. Each symbol represents an individual mouse or replicate and the line represents the group mean. Statistically significant differences were determined using a one-way ANOVA with Bonferroni’s post-test (*p < 0.05, **p < 0.01, ***p < 0.001, ns = not significant).</p