Crosstalk between keratinocytes and neutrophils shapes skin immunity against S. aureus infection

Introduction

Staphylococcus aureus (S. aureus) infection of the skin leads to a rapid initial innate immune response with keratinocytes in the epidermis as the initial sensors. Polymorphonuclear neutrophils (PMNs) are the first innate immune cells to infiltrate infection sites where they provide an effective first-line of defense. Previous work of our group showed that in inflamed skin a crosstalk between PMNs and keratinocytes results in enhanced S. aureus skin colonization.

Methods

In this work, we used an in vitro co-culture model to studied the crosstalk between primary human keratinocytes (PHKs) and PMNs in a sterile environment and upon S. aureus infection. We investigated the influence of PHKs on PMN activation by analyzing PMN lifespan, expression of degranulation markers and induction of proinflammatory cytokines. Furthermore, we analyzed the influence of PMNs on the inflammatory response of PHKs. Finally, we investigated the influence of the skin microbiome on PMN-mediated skin inflammation.

Results

We show that co-culture of PMNs with PHKs induces activation and degranulation of PMNs and significantly enhances their lifespan compared to PMN cultivation alone by an IL-8 mediated mechanism and, furthermore, primes PMNs for enhanced activity after S. aureus infection. The prolonged incubation with PMNs also induces inflammatory responses in PHKs which are further exacerbated in the presence of S. aureus and induces further PMN recruitment thus fueling skin inflammation. Interestingly, infection of PHKs with the skin commensal S. epidermidis reduces the inflammatory effects of PMNs in the skin and exhibits an anti-inflammatory effect.

Discussion

Our data indicate that skin infiltrating PMNs and PHKs influence each other in such a way to enhance skin inflammation and that commensal bacteria are able to reduce the inflammatory effect.

Infiltration of CD3+ and CD8+ lymphocytes in association with inflammation and survival in pancreatic cancer

BACKGROUND

Pancreatic ductal adenocarcinomas (PDAC) have heterogeneous tumor microenvironments relatively devoid of infiltrating immune cells. We aimed to quantitatively assess infiltrating CD3+ and CD8+ lymphocytes in a treatment-naïve patient cohort and assess associations with overall survival and microenvironment inflammatory proteins.

METHODS

Tissue microarrays were immunohistochemically stained for CD3+ and CD8+ lymphocytes and quantitatively assessed using QuPath. Levels of inflammation-associated proteins were quantified by multiplexed, enzyme-linked immunosorbent assay panels on matching tumor and tissue samples.

RESULTS

Our findings revealed a significant increase in both CD3+ and CD8+ lymphocytes populations in PDAC compared with non-PDAC tissue, except when comparing CD8+ percentages in PDAC versus intraductal papillary mucinous neoplasms (IPMN) (p = 0.5012). Patients with quantitatively assessed CD3+ low tumors (lower 50%) had shorter survival (median 273 days) compared to CD3+ high tumors (upper 50%) with a median overall survival of 642.5 days (p = 0.2184). Patients with quantitatively assessed CD8+ low tumors had significantly shorter survival (median 240 days) compared to CD8+ high tumors with a median overall survival of 1059 days (p = 0.0003). Of 41 proteins assessed in the inflammation assay, higher levels of IL-1B and IL-2 were significantly associated with decreased CD3+ infiltration (r = -0.3704, p = 0.0187, and r = -0.4275, p = 0.0074, respectively). Higher levels of IL-1B were also significantly associated with decreased CD8+ infiltration (r = -0.4299, p = 0.0045), but not IL-2 (r = -0.0078, p = 0.9616). Principal component analysis of the inflammatory analytes showed diverse inflammatory responses in PDAC.

CONCLUSION

In this work, we found a marked heterogeneity in infiltrating CD3+ and CD8+ lymphocytes and individual inflammatory responses in PDAC. Future mechanistic studies should explore personalized therapeutic strategies to target the immune and inflammatory components of the tumor microenvironment.

Cardiovascular manifestations of inflammatory bowel diseases and the underlying pathogenic mechanisms

Inflammatory bowel disease (IBD), consisting of ulcerative colitis and Crohn's disease, mainly affects the gastrointestinal tract but is also known to have extraintestinal manifestations because of long-standing systemic inflammation. Several national cohort studies have found that IBD is an independent risk factor for the development of cardiovascular disorders. However, the molecular mechanisms by which IBD impairs the cardiovascular system are not fully understood. Although the gut-heart axis is attracting more attention in recent years, our knowledge of the organ-to-organ communication between the gut and the heart remains limited. In patients with IBD, upregulated inflammatory factors, altered microRNAs and lipid profiles, as well as dysbiotic gut microbiota, may induce adverse cardiac remodeling. In addition, patients with IBD have a three- to four times higher risk of developing thrombosis than people without IBD, and it is believed that the increased risk of thrombosis is largely due to increased procoagulant factors, platelet count/activity, and fibrinogen concentration, in addition to decreased anticoagulant factors. The predisposing factors for atherosclerosis are present in IBD and the possible mechanisms may involve oxidative stress system, overexpression of matrix metalloproteinases, and changes in vascular smooth muscle phenotype. This review focuses mainly on 1) the prevalence of cardiovascular diseases associated with IBD, 2) the potential pathogenic mechanisms of cardiovascular diseases in patients with IBD, and 3) adverse effects of IBD drugs on the cardiovascular system. Also, we introduce here a new paradigm for the gut-heart axis that includes exosomal microRNA and the gut microbiota as a cause for cardiac remodeling and fibrosis.

Inhibition of Soluble Stem Cell Factor Promotes Intestinal Mucosal Repair

BACKGROUND

Incidences of inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, are escalating worldwide and can be considered a global public health problem. Given that the gold standard approach to IBD therapeutics focuses on reducing the severity of symptoms, there is an urgent unmet need to develop alternative therapies that halt not only inflammatory processes but also promote mucosal repair. Previous studies have identified increased stem cell factor (SCF) expression in inflamed intestinal mucosal tissues. However, the role that SCF plays in mediating intestinal inflammation and repair has not been explored.

METHODS

Changes in the expression of SCF were evaluated in the colonic tissue of healthy mice and during dextran sodium sulfate (DSS)-induced colitis. Furthermore, mucosal wound healing and colitis severity were analyzed in mice subjected to either mechanical biopsy or DSS treatment, respectively, following intestinal epithelial cell-specific deletion of SCF or anti-SCF antibody administration.

RESULTS

We report robust expression of SCF by intestinal epithelial cells during intestinal homeostasis with a switch to immune cell-produced SCF during colitis. Data from mice with intestinal epithelial cell-specific deletion of SCF highlight the importance of immune cell-produced SCF in driving the pathogenesis of colitis. Importantly, antibody-mediated neutralization of total SCF or the specific SCF248 isoform decreased immune cell infiltration and enhanced mucosal wound repair following biopsy-induced colonic injury or DSS-induced colitis.

CONCLUSIONS

These data demonstrate that SCF functions as a pro-inflammatory mediator in mucosal tissues and that specific neutralization of SCF248 could be a viable therapeutic option to reduce intestinal inflammation and promote mucosal wound repair in individuals with IBD.

Polysialylation controls immune function of myeloid cells in murine model of pneumococcal pneumonia

Polysialic acid (polySia) is a post-translational modification of a select group of cell-surface proteins that guides cellular interactions. As the overall impact of changes in expression of this glycan on leukocytes during infection is not known, we evaluate the immune response of polySia-deficient ST8SiaIV-/- mice infected with Streptococcus pneumoniae (Spn). Compared with wild-type (WT) mice, ST8SiaIV-/- mice are less susceptible to infection and clear Spn from airways faster, with alveolar macrophages demonstrating greater viability and phagocytic activity. Leukocyte pulmonary recruitment, paradoxically, is diminished in infected ST8SiaIV-/- mice, corroborated by adoptive cell transfer, microfluidic migration experiments, and intravital microscopy, and possibly explained by dysregulated ERK1/2 signaling. PolySia is progressively lost from neutrophils and monocytes migrating from bone marrow to alveoli in Spn-infected WT mice, consistent with changing cellular functions. These data highlight multidimensional effects of polySia on leukocytes during an immune response and suggest therapeutic interventions for optimizing immunity.

Pathogenesis of Anemia in Canine Babesiosis: Possible Contribution of Pro-Inflammatory Cytokines and Chemokines-A Review

Canine babesiosis is a tick-borne protozoan disease caused by intraerythrocytic parasites of the genus Babesia. The infection may lead to anemia in infected dogs. However, anemia is not directly caused by the pathogen. The parasite's developmental stages only have a marginal role in contributing to a decreased red blood cell (RBC) count. The main cause of anemia in affected dogs is the immune response to the infection. This response includes antibody production, erythrophagocytosis, oxidative damage of RBCs, complement activation, and antibody-dependent cellular cytotoxicity. Moreover, both infected and uninfected erythrocytes are retained in the spleen and sequestered in micro-vessels. All these actions are driven by pro-inflammatory cytokines and chemokines, especially IFN-γ, TNF-α, IL-6, and IL-8. Additionally, imbalance between the actions of pro- and anti-inflammatory cytokines plays a role in patho-mechanisms leading to anemia in canine babesiosis. This article is a review of the studies on the pathogenesis of anemia in canine babesiosis and related diseases, such as bovine or murine babesiosis and human or murine malaria, and the role of pro-inflammatory cytokines and chemokines in the mechanisms leading to anemia in infected dogs.

A novel Pseudorabies virus vaccine developed using HDR-CRISPR/Cas9 induces strong humoral and cellular immune response in mice

Outbreaks of Pseudorabies (PR) by numerous highly virulent and antigenic variant Pseudorabies virus (PRV) strains have been causing severe economic losses to the pig industry in China since 2011. However, current commercial vaccines are often unable to induce thorough protective immunity. In this study, a TK/gI/gE deleted recombinant PRV expressing GM-CSF was developed by using the HDR-CRISPR/Cas9 system. Here, a four-sgRNA along with the Cas9^D10A targeting system was utilized for TK/gI/gE gene deletion and GM-CSF insertion. Our study showed that the four-sgRNA targeting system appeared to have higher knock-in efficiency for PRVs editing. The replication of the recombinant PRVs were slightly lower than that of the parental strain, but they appeared to have similar properties in terms of growth curves and plaque morphology. The mice vaccinated with the recombinant PRV expressing GM-CSF via intramuscular injection showed no obvious clinical symptoms, milder pathological lesions, and were completely protected against wild-type PRV challenge. When compared to the triple gene-deleted PRV, the gB antibodies and neutralizing antibody titers were improved and the immunized mice appeared to have lower viral load and higher mRNA levels of IL-2, IL-4, IL-6, and IFN-γ in spleens. Our study offers a novel approach for recombinant PRV construction, and the triple gene-deleted PRV expressing GM-CSF could serve as a promising vaccine candidate for PR control.

Biological Risk Assessment of Three Dental Composite Materials following Gas Plasma Exposure

Gas plasma is an approved technology that generates a plethora of reactive oxygen species, which are actively applied for chronic wound healing. Its particular antimicrobial action has spurred interest in other medical fields, such as periodontitis in dentistry. Recent work has indicated the possibility of performing gas plasma-mediated biofilm removal on teeth. Teeth frequently contain restoration materials for filling cavities, e.g., resin-based composites. However, it is unknown if such materials are altered upon gas plasma exposure. To this end, we generated a new in-house workflow for three commonly used resin-based composites following gas plasma treatment and incubated the material with human HaCaT keratinocytes in vitro. Cytotoxicity was investigated by metabolic activity analysis, flow cytometry, and quantitative high-content fluorescence imaging. The inflammatory consequences were assessed using quantitative analysis of 13 different chemokines and cytokines in the culture supernatants. Hydrogen peroxide served as the control condition. A modest but significant cytotoxic effect was observed in the metabolic activity and viability after plasma treatment for all three composites. This was only partially treatment time-dependent and the composites alone affected the cells to some extent, as evident by differential secretion profiles of VEGF, for example. Gas plasma composite modification markedly elevated the secretion of IL6, IL8, IL18, and CCL2, with the latter showing the highest correlation with treatment time (Pearson’s r > 0.95). Cell culture media incubated with gas plasma-treated composite chips and added to cells thereafter could not replicate the effects, pointing to the potential that surface modifications elicited the findings. In conclusion, our data suggest that gas plasma treatment modifies composite material surfaces to a certain extent, leading to measurable but overall modest biological effects.

Necrotizing Gingivitis: Microbial Diversity and Quantification of Protein Secretion in Necrotizing Gingivitis

Necrotizing gingivitis (NG) is a necrotizing periodontal disease that differs from chronic gingivitis (CG). To date, both the microbiological causes and the involved host cytokine response of NG still remain unclear. Here, we investigated corresponding interdental plaque and serum samples from two groups of Chinese patients with CG (n = 21) or NG (n = 21). The microbiota were studied by 16S rRNA Illumina MiSeq sequencing of the microbial metagenome and by assessing quantitatively the abundance of the phylum Bacteroidetes, the genus Prevotella and the species T. forsythia, P. endodontalis, and P. gingivalis using fluorescence in situ hybridization (FISH). With respect to the associated host response, the levels of 30 inflammatory mediators were quantified by multiplex immunoassay analysis. Differential microbial abundance analysis of the two disease groups revealed at the phylum level that Proteobacteria accounted for 67% of the differentially abundant organisms, followed by organisms of Firmicutes (21%) and Actinobacteria (9%). At the species level, significant differences in abundance were seen for 75 species of which 58 species were significantly more abundant in CG patients. Notably, the FISH analysis revealed that Bacteroidetes was the most prevalent phylum in NG. The multiplex cytokine assay showed significant quantitative differences between the disease groups for eight analytes (GM–CSF, G–CSF, IFN–α, IL–4, IL–13, TNF–α, MIG, and HGF). The G–CSF was found to be the most significantly increased inflammatory protein marker in NG. The next-generation sequencing (NGS) data supported the understanding of NG as a multi-microbial infection with distinct differences to CG in regard to the microbial composition.

STAT4 is expressed in neutrophils and promotes antimicrobial immunity

Signal transducer and activator of transcription 4 (STAT4) is expressed in hematopoietic cells and plays a key role in the differentiation of T helper 1 cells. Although STAT4 is required for immunity to intracellular pathogens, the T cell-independent protective mechanisms of STAT4 are not clearly defined. In this report, we demonstrate that STAT4-deficient mice were acutely sensitive to methicillin-resistant Staphylococcus aureus (MRSA) infection. We show that STAT4 was expressed in neutrophils and activated by IL-12 via a JAK2-dependent pathway. We demonstrate that STAT4 was required for multiple neutrophil functions, including IL-12-induced ROS production, chemotaxis, and production of the neutrophil extracellular traps. Importantly, myeloid-specific and neutrophil-specific deletion of STAT4 resulted in enhanced susceptibility to MRSA, demonstrating the key role of STAT4 in the in vivo function of these cells. Thus, these studies identify STAT4 as an essential regulator of neutrophil functions and a component of innate immune responses in vivo.

Human macrophages utilize a wide range of pathogen recognition receptors to recognize Legionella pneumophila, including Toll-Like Receptor 4 engaging Legionella lipopolysaccharide and the Toll-like Receptor 3 nucleic-acid sensor

Cytokines made by macrophages play a critical role in determining the course of Legionella pneumophila infection. Prior murine-based modeling indicated that this cytokine response is initiated upon recognition of L. pneumophila by a subset of Toll-like receptors, namely TLR2, TLR5, and TLR9. Through the use of shRNA/siRNA knockdowns and subsequently CRISPR/Cas9 knockouts (KO), we determined that TRIF, an adaptor downstream of endosomal TLR3 and TLR4, is required for full cytokine secretion by human primary and cell-line macrophages. By characterizing a further set of TLR KO's in human U937 cells, we discerned that, contrary to the viewpoint garnered from murine-based studies, TLR3 and TLR4 (along with TLR2 and TLR5) are in fact vital to the macrophage response in the early stages of L. pneumophila infection. This conclusion was bolstered by showing that i) chemical inhibitors of TLR3 and TLR4 dampen the cytokine output of primary human macrophages and ii) transfection of TLR3 and TLR4 into HEK cells conferred an ability to sense L. pneumophila. TLR3- and TLR4-dependent cytokines promoted migration of human HL-60 neutrophils across an epithelial layer, pointing to the biological importance for the newfound signaling pathway. The response of U937 cells to L. pneumophila LPS was dependent upon TLR4, a further contradiction to murine-based studies, which had concluded that TLR2 is the receptor for Legionella LPS. Given the role of TLR3 in sensing nucleic acid (i.e., dsRNA), we utilized newly-made KO U937 cells to document that DNA-sensing by cGAS-STING and DNA-PK are also needed for the response of human macrophages to L. pneumophila. Given the lack of attention given them in the bacterial field, C-type lectin receptors were similarly examined; but, they were not required. Overall, this study arguably represents the most extensive, single-characterization of Legionella-recognition receptors within human macrophages.

Intestinal Infection Is Associated With Impaired Lung Innate Immunity to Secondary Respiratory Infection

Background

Pneumonia and diarrhea are among the leading causes of death worldwide, and epidemiological studies have demonstrated that diarrhea is associated with an increased risk of subsequent pneumonia. Our aim was to determine the impact of intestinal infection on innate immune responses in the lung.

Methods

Using a mouse model of intestinal infection by Salmonella enterica serovar Typhimurium (S. Typhimurium [ST]), we investigated associations between gastrointestinal infections and lung innate immune responses to bacterial (Klebsiella pneumoniae) challenge.

Results

We found alterations in frequencies of innate immune cells in the lungs of intestinally infected mice compared with uninfected mice. On subsequent challenge with K. pneumoniae, we found that mice with prior intestinal infection have higher lung bacterial burden and inflammation, increased neutrophil margination, and neutrophil extracellular traps, but lower overall numbers of neutrophils, compared with mice without prior intestinal infection. Total numbers of dendritic cells, innate-like T cells, and natural killer cells were not different between mice with and without prior intestinal infection.

Conclusions

Together, these results suggest that intestinal infection impacts lung innate immune responses, most notably neutrophil characteristics, potentially resulting in increased susceptibility to secondary pneumonia.

Granulocyte macrophage colony-stimulating factor has come of age: From a vaccine adjuvant to antiviral immunotherapy

GM-CSF acts as a pro-inflammatory cytokine and a key growth factor produced by several immune cells such as macrophages and activated T cells. In this review, we discuss recent studies that point to the crucial role of GM-CSF in the immune response against infections. Upon induction, GM-CSF activates four main signalling networks including the JAK/STAT, PI3K, MAPK, and NFκB pathways. Many of these transduction pathways such as JAK/STAT signal via proteins commonly activated with other antiviral signalling cascades, such as those induced by IFNs. GM-CSF also helps defend against respiratory infections by regulating alveolar macrophage differentiation and enhancing innate immunity in the lungs. Here, we also summarize the numerous clinical trials that have taken advantage of GM-CSF's mechanistic attributes in immunotherapy. Moreover, we discuss how GM-CSF is used as an adjuvant in vaccines and how its activity is interfered with to reduce inflammation such as in the case of COVID-19. This review brings forth the current knowledge on the antiviral actions of GM-CSF, the associated signalling cascades, and its application in immunotherapy.

Onion bulb extract can both reverse and prevent colitis in mice via inhibition of pro-inflammatory signaling molecules and neutrophil activity

Background

Onion is one of the most commonly used plants in the traditional medicine for the treatment of various diseases. We recently demonstrated the anti-inflammatory properties of onion bulb extract (OBE) in reducing colitis severity in mice when administered at the same time of colitis induction. However, whether onion can reverse established colitis or even prevent its development has not been investigated.

Hypothesis

To test 1. whether OBE can reduce colitis severity when given either before (preventative approach) or after (treatment approach) colitis induction and if so, 2. what are the mechanisms by which onion can achieve these effects.

Methods

Colitis was induced by dextran sulfate sodium (DSS) administration using treatment and preventative approaches. The severity of the inflammation was determined by the gross and histological assessments. The colonic level/activity of pro-inflammatory molecules and immune cell markers was assessed by immunofluorescence and western blotting analysis. In vitro neutrophil superoxide release and survival was assessed by chemilumenecense and Annexin-V/7AAD assays respectively.

Results

OBE treatment significantly reduced colitis severity in both approaches, the colonic expression/activity profile of pro-inflammatory molecules, inhibited WKYMVm-induced superoxide release, and increased spontaneous apoptosis of neutrophils in vitro.

Conclusions

OBE can be used as an effective option in the prevention and/or the treatment of established colitis.

GM-CSF in inflammation

GM-CSF is a potential therapeutic target in inflammation and autoimmunity. This study reviews the literature on the biology of GM-CSF, in particular that describing the research leading to clinical trials targeting GM-CSF and its receptor in numerous inflammatory/autoimmune conditions, such as rheumatoid arthritis.

Granulocyte–macrophage colony-stimulating factor (GM-CSF) has many more functions than its original in vitro identification as an inducer of granulocyte and macrophage development from progenitor cells. Key features of GM-CSF biology need to be defined better, such as the responding and producing cell types, its links with other mediators, its prosurvival versus activation/differentiation functions, and when it is relevant in pathology. Significant preclinical data have emerged from GM-CSF deletion/depletion approaches indicating that GM-CSF is a potential target in many inflammatory/autoimmune conditions. Clinical trials targeting GM-CSF or its receptor have shown encouraging efficacy and safety profiles, particularly in rheumatoid arthritis. This review provides an update on the above topics and current issues/questions surrounding GM-CSF biology.

STIM1-mediated calcium influx controls antifungal immunity and the metabolic function of non-pathogenic Th17 cells

Immunity to fungal infections is mediated by cells of the innate and adaptive immune system including Th17 cells. Ca²⁺ influx in immune cells is regulated by stromal interaction molecule 1 (STIM1) and its activation of the Ca²⁺ channel ORAI1. We here identify patients with a novel mutation in STIM1 (p.L374P) that abolished Ca²⁺ influx and resulted in increased susceptibility to fungal and other infections. In mice, deletion of STIM1 in all immune cells enhanced susceptibility to mucosal C. albicans infection, whereas T cell‐specific deletion of STIM1 impaired immunity to systemic C. albicans infection. STIM1 deletion impaired the production of Th17 cytokines essential for antifungal immunity and compromised the expression of genes in several metabolic pathways including Foxo and HIF1α signaling that regulate glycolysis and oxidative phosphorylation (OXPHOS). Our study further revealed distinct roles of STIM1 in regulating transcription and metabolic programs in non‐pathogenic Th17 cells compared to pathogenic, proinflammatory Th17 cells, a finding that may potentially be exploited for the treatment of Th17 cell‐mediated inflammatory diseases.

Thrombin-Induced Decidual Colony-Stimulating Factor-2 Promotes Abruption-Related Preterm Birth by Weakening Fetal Membranes

Preterm premature rupture of membranes (PPROM) and thrombin generation by decidual cell-expressed tissue factor often accompany abruptions. Underlying mechanisms remain unclear. We hypothesized that thrombin-induced colony-stimulating factor-2 (CSF-2) in decidual cells triggers paracrine signaling via its receptor (CSF2R) in trophoblasts, promoting fetal membrane weakening and abruption-associated PPROM. Decidua basalis sections from term (n = 10), idiopathic preterm birth (PTB; n = 8), and abruption-complicated pregnancies (n = 8) were immunostained for CSF-2. Real-time quantitative PCR measured CSF2 and CSF2R mRNA levels. Term decidual cell (TDC) monolayers were treated with 10^-8 mol/L estradiol ± 10^-7 mol/L medroxyprogesterone acetate (MPA) ± 1 IU/mL thrombin pretreatment for 4 hours, washed, and then incubated in control medium with estradiol ± MPA. TDC-derived conditioned media supernatant effects on fetal membrane weakening were analyzed. Immunostaining localized CSF-2 primarily to decidual cell cytoplasm and cytotrophoblast cell membranes. CSF-2 immunoreactivity was higher in abruption-complicated or idiopathic PTB specimens versus normal term specimens (P < 0.001). CSF2 mRNA was higher in TDCs versus cytotrophoblasts (P < 0.05), whereas CSF2R mRNA was 1.3 × 10⁴-fold higher in cytotrophoblasts versus TDCs (P < 0.001). Thrombin enhanced CSF-2 secretion in TDC cultures fourfold (P < 0.05); MPA reduced this effect. Thrombin-pretreated TDC-derived conditioned media supernatant weakened fetal membranes (P < 0.05), which MPA inhibited. TDC-derived CSF-2, acting via trophoblast-expressed CSFR2, contributes to thrombin-induced fetal membrane weakening, eliciting abruption-related PPROM and PTB.

Airway exposure to Staphylococcal enterotoxin type B (SEB) enhances the number and activity of bone marrow neutrophils via the release of multiple cytokines

BACKGROUND

The lung infections by Staphylococcus aureus are strongly associated with its ability to produce enterotoxins. However, little is known about the mechanisms underlying trafficking of bone marrow (BM) neutrophils during airway inflammation induced by Staphylococcal enterotoxin B (SEB). We therefore aimed to investigate the effects of mouse airways SEB exposure on BM neutrophil counts and its adhesive properties as well as on the release of cytokines/chemokines that orchestrate BM neutrophils trafficking to lung tissue.

METHODS

Male BALB/c mice were intranasally exposed to SEB (1 µg), and at 4, 16 and 24 h thereafter, BM, circulating blood, bronchoalveolar lavage (BAL) fluid and lung tissue were collected. BM neutrophils adhesion, MAC-1 and LFA1-α expressions (by flow cytometry) as well as measurement of cytokine and/or chemokines levels were assayed after SEB-airway exposure.

RESULTS

Prior exposure to SEB promoted a marked influx of neutrophils to BAL and lung tissue, which was accompanied by increased counts of BM immature neutrophils and blood neutrophilia. BM neutrophil expressions of LFA1-α and MAC-1 were unchanged by SEB exposure whereas a significant enhancement of adhesion properties to VCAM-1 was observed. The early phase of airway SEB exposure was accompanied by high levels of GM-CSF, G-CSF, IFN-γ, TNF-α and KC/CXCL1, while the latter phase by the equilibrated actions of SDF1-α and MIP-2.

CONCLUSION

Mouse airways exposure to SEB induces BM cytokines/chemokines release and their integrated actions enhance the adhesion of BM neutrophils leading to acute lung injury.

IgA and FcαRI: Pathological Roles and Therapeutic Opportunities

Immunoglobulin A (IgA) is the most abundant antibody class present at mucosal surfaces. The production of IgA exceeds the production of all other antibodies combined, supporting its prominent role in host-pathogen defense. IgA closely interacts with the intestinal microbiota to enhance its diversity, and IgA has a passive protective role via immune exclusion. Additionally, inhibitory ITAMi signaling via the IgA Fc receptor (FcαRI; CD89) by monomeric IgA may play a role in maintaining homeostatic conditions. By contrast, IgA immune complexes (e.g., opsonized pathogens) potently activate immune cells via cross-linking FcαRI, thereby inducing pro-inflammatory responses resulting in elimination of pathogens. The importance of IgA in removal of pathogens is emphasized by the fact that several pathogens developed mechanisms to break down IgA or evade FcαRI-mediated activation of immune cells. Augmented or aberrant presence of IgA immune complexes can result in excessive neutrophil activation, potentially leading to severe tissue damage in multiple inflammatory, or autoimmune diseases. Influencing IgA or FcαRI-mediated functions therefore provides several therapeutic possibilities. On the one hand (passive) IgA vaccination strategies can be developed for protection against infections. Furthermore, IgA monoclonal antibodies that are directed against tumor antigens may be effective as cancer treatment. On the other hand, induction of ITAMi signaling via FcαRI may reduce allergy or inflammation, whereas blocking FcαRI with monoclonal antibodies, or peptides may resolve IgA-induced tissue damage. In this review both (patho)physiological roles as well as therapeutic possibilities of the IgA-FcαRI axis are addressed.

Biomaterials for vaccine-based cancer immunotherapy

The development of therapeutic cancer vaccines as a means to generate immune reactivity against tumors has been explored since the early discovery of tumor-specific antigens by Georg Klein in the 1960s. However, challenges including weak immunogenicity, systemic toxicity, and off-target effects of cancer vaccines remain as barriers to their broad clinical translation. Advances in the design and implementation of biomaterials are now enabling enhanced efficacy and reduced toxicity of cancer vaccines by controlling the presentation and release of vaccine components to immune cells and their microenvironment. Here, we discuss the rational design and clinical status of several classes of cancer vaccines (including DNA, mRNA, peptide/protein, and cell-based vaccines) along with novel biomaterial-based delivery technologies that improve their safety and efficacy. Further, strategies for designing new platforms for personalized cancer vaccines are also considered.

House dust mite-driven neutrophilic airway inflammation in mice with TNFAIP3-deficient myeloid cells is IL-17-independent

BACKGROUND

Asthma is a heterogeneous disease of the airways that involves several types of granulocytic inflammation. Recently, we have shown that the activation status of myeloid cells regulated by TNFAIP3/A20 is a crucial determinant of eosinophilic or neutrophilic airway inflammation. However, whether neutrophilic inflammation observed in this model is dependent on IL-17 remains unknown.

OBJECTIVE

In this study, we investigated whether IL-17RA-signalling is essential for eosinophilic or neutrophilic inflammation in house dust mite (HDM)-driven airway inflammation.

METHODS

Tnfaip3^fl/fl xLyz2^+/cre (Tnfaip3^LysM-KO ) mice were crossed to Il17ra^KO mice, generating Tnfaip3^LysM Il17ra^KO mice and subjected to an HDM-driven airway inflammation model.

RESULTS

Both eosinophilic and neutrophilic inflammation observed in HDM-exposed WT and Tnfaip3^LysM-KO mice respectively were unaltered in the absence of IL-17RA. Production of IL-5, IL-13 and IFN-γ by CD4⁺ T cells was similar between WT, Tnfaip3^LysM-KO and Il17ra^KO mice, whereas mucus-producing cells in Tnfaip3^LysM-KO Il17ra^KO mice were reduced compared to controls. Strikingly, spontaneous accumulation of pulmonary Th1, Th17 and γδ-17 T cells was observed in Tnfaip3^LysM-KO Il17ra^KO mice, but not in the other genotypes. Th17 cell-associated cytokines such as GM-CSF and IL-22 were increased in the lungs of HDM-exposed Tnfaip3^LysM-KO Il17ra^KO mice, compared to IL-17RA-sufficient controls. Moreover, neutrophilic chemo-attractants CXCL1, CXCL2, CXCL12 and Th17-promoting cytokines IL-1β and IL-6 were unaltered between Tnfaip3^LysM-KO and Tnfaip3^LysM-KO Il17ra^KO mice.

CONCLUSION AND CLINICAL RELEVANCE

These findings show that neutrophilic airway inflammation induced by activated TNFAIP3/A20-deficient myeloid cells can develop in the absence of IL-17RA-signalling. Neutrophilic inflammation is likely maintained by similar quantities of pro-inflammatory cytokines IL-1β and IL-6 that can, independently of IL-17-signalling, induce the expression of neutrophil chemo-attractants.

Intranasal administration of cationic liposomes enhanced granulocyte-macrophage colony-stimulating factor expression and this expression is dispensable for mucosal adjuvant activity

Objective

Infectious diseases remain a threat to human life. Vaccination against pathogenic microbes is a primary method of treatment as well as prevention of infectious diseases. Particularly mucosal vaccination is a promising approach to fight against most infectious diseases, because mucosal surfaces are a major point of entry for most pathogens. We recently developed an effective mucosal adjuvant of cationic liposomes composed of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) and 3β-[N-(N′,N′-dimethylaminoethane)-carbamoyl] (DC-chol) (DOTAP/DC-chol liposomes). However, the mechanism(s) underlying the mucosal adjuvant effects exerted by the cationic liposomes have been unclear. In this study, we investigated the role of granulocyte–macrophage colony-stimulating factor (GM-CSF), which was reported to act as a mucosal adjuvant, on the mucosal adjuvant activities of DOTAP/DC-chol liposomes when administered intranasally to mice.

Results

Here, we show that, although intranasal vaccination with cationic liposomes in combination with antigenic protein elicited GM-CSF expression at the site of administration, blocking GM-CSF function by using an anti-GM-CSF neutralizing antibody did not alter antigen-specific antibody production induced by DOTAP/DC-chol liposomes, indicating that GM-CSF may not contribute to the mucosal adjuvant activity of the cationic liposomes when administered intranasally.

Electronic supplementary material

The online version of this article (10.1186/s13104-018-3591-3) contains supplementary material, which is available to authorized users.

The role of granulocyte macrophage colony stimulating factor in hospitalized children with Mycoplasma pneumoniae pneumonia

BACKGROUND

Inappropriate inflammatory response in children with M. pneumoniae infection might be associated with disease severity. The role of Granulocyte macrophage colony stimulating factor (GM-CSF) in hospitalized children with Mycoplasma pneumoniae pneumonia (MPP) has not been fully discussed.

METHODS

Clinical and laboratory data of a total 40 children with MPP were collected. GM-CSF and myeloperoxidase (MPO) were detected by ELISAs. Meanwhile, normal human bronchial epithelium was infected by M. pneumoniae and neutrophils were stimulated by GM-CSF to explore GM-CSF and MPO release in supernatant, respectively.

RESULTS

Compared to control group, a significant increased percentage of neutrophils and decreased percentage of macrophages in bronchoalveolar lavage fluid of children with MPP was observed (P < 0.05). Children with MPP had significantly higher levels of GM-CSF (P = 0.0047) and MPO (P = 0.0002) in BALF compared to the controls. Level of GM-CSF in BALF was associated with duration of fever (r = 0.42, P = 0.007) and strongly correlated with level of MPO (r = 0.075, P = 0.0005). Levels of GM-CSF and MPO significantly decreased (both P < 0.05) after treatment. In vitro, M. pneumoniae induced GM-CSF expression in a time-dependent manner during a 72-h period (P < 0.05) and MPO secretion significantly increased by recombinant human GM-CSF stimulation at 24h (P < 0.05).

CONCLUSION

GM-CSF could be induced by M. pneumoniae infection in vivo and vitro. Childen with high level GM-CSF had longer duration of fever. GM-CSF probably plays a vital role in neutrophil inflammation in M. pneumoniae infection.

GM-CSF improves the immune response to the diphtheria-component in a multivalent vaccine

Multivalent tetanus and diphtheria toxoid containing vaccines belong to the most frequently applied vaccines. However, there is an imbalance in the degree of protection against the two antigens with insufficient long-term protection against diphtheria, particularly in the elderly population. We have previously reported a positive correlation between granulocyte macrophage-colony stimulating factor (GM-CSF) and the production of diphtheria-specific antibodies. Therefore, in the present study we analyzed the effects of in vivo applied recombinant GM-CSF on immunization with multivalent tetanus/diphtheria vaccine in mice of different age. In vivo application of GM-CSF lead to enhanced production of diphtheria-specific antibodies as well as more diphtheria-specific CD4⁺ T cells following vaccination with multivalent tetanus/diphtheria vaccine. In contrast, the humoral and cellular immune response to the tetanus component was unaltered. Furthermore, application of GM-CSF resulted in more splenic CD11b⁺ dendritic cells (DCs) with a higher MHC-II expression. GM-CSF also induced a stronger recruitment of CD11b⁺ DCs to the injected muscle. Most remarkably, GM-CSF was able to boost the diphtheria-specific immune response to the multivalent vaccine in aged mice. This study demonstrates that local administration of GM-CSF is able to improve immune responsiveness to the diphtheria component of multivalent tetanus/diphtheria vaccine in young and old mice. This information could be useful for the future design of vaccines for the elderly.

Neutrophils in traumatic brain injury (TBI): friend or foe?

Our knowledge of the pathophysiology about traumatic brain injury (TBI) is still limited. Neutrophils, as the most abundant leukocytes in circulation and the first-line transmigrated immune cells at the sites of injury, are highly involved in the initiation, development, and recovery of TBI. Nonetheless, our understanding about neutrophils in TBI is obsolete, and mounting evidences from recent studies have challenged the conventional views. This review summarizes what is known about the relationships between neutrophils and pathophysiology of TBI. In addition, discussions are made on the complex roles as well as the controversial views of neutrophils in TBI.

Human resistin protects against endotoxic shock by blocking LPS-TLR4 interaction

Helminths trigger multiple immunomodulatory pathways that can protect from sepsis. Human resistin (hRetn) is an immune cell-derived protein that is highly elevated in helminth infection and sepsis. However, the function of hRetn in sepsis, or whether hRetn influences helminth protection against sepsis, is unknown. Employing hRetn-expressing transgenic mice (hRETNTg⁺) and recombinant hRetn, we identify a therapeutic function for hRetn in lipopolysaccharide (LPS)-induced septic shock. hRetn promoted helminth-induced immunomodulation, with increased survival of Nippostrongylus brasiliensis (Nb)-infected hRETNTg⁺ mice after a fatal LPS dose compared with naive mice or Nb-infected hRETNTg^- mice. Employing immunoprecipitation assays, hRETNTg⁺Tlr4^-/- mice, and human immune cell culture, we demonstrate that hRetn binds the LPS receptor Toll-like receptor 4 (TLR4) through its N terminal and modulates STAT3 and TBK1 signaling, triggering a switch from proinflammatory to anti-inflammatory responses. Further, we generate hRetn N-terminal peptides that are able to block LPS proinflammatory function. Together, our studies identify a critical role for hRetn in blocking LPS function with important clinical significance in helminth-induced immunomodulation and sepsis.

Anti-inflammatory action of angiotensin 1-7 in experimental colitis may be mediated through modulation of serum cytokines/chemokines and immune cell functions

We recently demonstrated Ang 1-7 reduced inflammation in the dextran sulfate sodium (DSS) colitis model. In this study we examined the effect of Ang 1-7 on modulation of plasma levels of selected cytokines and chemokines and immune cell effector functions (apoptosis, chemotaxis and superoxide release) in vitro. The degree of neutrophil recruitment to the colon was assessed by immunofluorescence and myeloperoxidase activity. Daily Ang 1-7 treatment at 0.01 mg/kg dose which previously ameliorated colitis severity, showed a significant reduction in circulating levels of several cytokines and chemokines, and neutrophil recruitment to the colonic tissue. It also significantly enhanced immune cell apoptosis, and reduced neutrophil chemotaxis and superoxide release in vitro. In contrast, daily administration of the Ang 1-7R antagonist A779 which previously worsened colitis severity showed significant up-regulation of specific mediators. Our results demonstrate a novel anti-inflammatory action of Ang 1-7 through modulation of plasma levels of cytokines/chemokines and immune cell activity.

Src-dependent EGFR transactivation regulates lung inflammation via downstream signaling involving ERK1/2, PI3Kδ/Akt and NFκB induction in a murine asthma model

The molecular mechanisms underlying asthma pathogenesis are poorly characterized. In this study, we investigated (1) whether Src mediates epidermal growth factor receptor (EGFR) transactivation; (2) if ERK1/2, PI3Kδ/Akt and NF-κB are signaling effectors downstream of Src/EGFR activation; and (3) if upstream inhibition of Src/EGFR is more effective in downregulating the allergic inflammation than selective inhibition of downstream signaling pathways. Allergic inflammation resulted in increased phosphorylation of EGFR, Akt, ERK1/2 and IκB in the lung tissues from ovalbumin (OVA)-challenged BALB/c mice. Treatment with inhibitors of Src (SU6656) or EGFR (AG1478) reduced EGFR phosphorylation and downstream signaling which resulted in the inhibition of the OVA-induced inflammatory cell influx in bronchoalveolar lavage fluid (BALF), perivascular and peribronchial inflammation, fibrosis, goblet cell hyper/metaplasia and airway hyper-responsiveness. Treatment with pathway-selective inhibitors for ERK1/2 (PD89059) and PI3Kδ/Akt (IC-87114) respectively, or an inhibitor of NF-κB (BAY11-7085) also reduced the OVA-induced asthmatic phenotype but to a lesser extent compared to Src/EGFR inhibition. Thus, Src via EGFR transactivation and subsequent downstream activation of multiple pathways regulates the allergic airway inflammatory response. Furthermore, a broader upstream inhibition of Src/EGFR offers an attractive therapeutic alternative in the treatment of asthma relative to selectively targeting the individual downstream signaling effectors.

Targeting the GM-CSF receptor for the treatment of CNS autoimmunity

In multiple sclerosis (MS), there is a growing interest in inhibiting the pro-inflammatory effects of granulocyte-macrophage colony-stimulating factor (GM-CSF). We sought to evaluate the therapeutic potential and underlying mechanisms of GM-CSF receptor alpha (Rα) blockade in animal models of MS. We show that GM-CSF signaling inhibition at peak of chronic experimental autoimmune encephalomyelitis (EAE) results in amelioration of disease progression. Similarly, GM-CSF Rα blockade in relapsing-remitting (RR)-EAE model prevented disease relapses and inhibited T cell responses specific for both the inducing and spread myelin peptides, while reducing activation of mDCs and inflammatory monocytes. In situ immunostaining of lesions from human secondary progressive MS (SPMS), but not primary progressive MS patients shows extensive recruitment of GM-CSF Rα⁺ myeloid cells. Collectively, this study reveals a pivotal role of GM-CSF in disease relapses and the benefit of GM-CSF Rα blockade as a potential novel therapeutic approach for treatment of RRMS and SPMS.

GM-CSF is not essential for experimental autoimmune encephalomyelitis but promotes brain-targeted disease

Experimental autoimmune encephalomyelitis (EAE) has been used as an animal model of multiple sclerosis to identify pathogenic cytokines that could be therapeutic targets. Granulocyte-macrophage colony-stimulating factor (GM-CSF) is the only cytokine reported to be essential for EAE. We investigated the role of GM-CSF in EAE in C3HeB/FeJ mice that uniquely exhibit extensive brain and spinal cord inflammation. Unexpectedly, GM-CSF-deficient C3HeB/FeJ mice were fully susceptible to EAE because IL-17 activity compensated for the loss of GM-CSF during induction of spinal cord-targeted disease. In contrast, both GM-CSF and IL-17 were needed to fully overcome the inhibitory influence of IFN-γ on the induction of inflammation in the brain. Both GM-CSF and IL-17 independently promoted neutrophil accumulation in the brain, which was essential for brain-targeted disease. These results identify a GM-CSF/IL-17/IFN-γ axis that regulates inflammation in the central nervous system and suggest that a combination of cytokine-neutralizing therapies may be needed to dampen central nervous system autoimmunity.

Anti-Inflammatory Properties of the Enaminone E121 in the Dextran Sulfate Sodium (DSS) Colitis Model

BACKGROUND

Enaminones are synthetic compounds with an established role in the prevention of various forms of seizures. Recent evidence suggests potent anti-tussive, bronchodilation and anti-inflammatory properties. Pre-treatment with particularly E121 compound resulted in a decrease in leukocyte recruitment in the ovalbumin induced-model of asthma, immune cell proliferation and cytokine release in vitro. We hypothesize that E121 might serve as a therapeutic potential in intestinal inflammation through modulating immune cell functions.

METHODS

Colitis was induced by daily dextran sulfate sodium (DSS) administration for 5 days, and its severity was determined by gross and histological assessments. The plasma level of various cytokines was measured using flow cytometry-based assay. The colonic expression/ phosphorylation level of various molecules was determined by immunofluorescence and western blotting. The effects of E121 treatment on in vitro neutrophil chemotaxis (under-agarose assay), superoxide release (luminol oxidation assay) and apoptosis (annexin V/7AAD) were also determined.

RESULTS

DSS-induced colitis in mice was significantly reduced by daily E121 treatment (30-100 mg/kg) at gross and histological levels. This effect was due to modulated plasma levels of interleukin (IL-2) and colonic expression levels of various signaling molecules and proteins involved in apoptosis. In vitro neutrophil survival, chemotaxis, and superoxide release were also reduced by E121 treatment.

CONCLUSION

Our results indicate important anti-inflammatory actions of E121 in the pathogenesis of IBD.

Non-invasive Imaging of Sendai Virus Infection in Pharmacologically Immunocompromised Mice: NK and T Cells, but not Neutrophils, Promote Viral Clearance after Therapy with Cyclophosphamide and Dexamethasone

In immunocompromised patients, parainfluenza virus (PIV) infections have an increased potential to spread to the lower respiratory tract (LRT), resulting in increased morbidity and mortality. Understanding the immunologic defects that facilitate viral spread to the LRT will help in developing better management protocols. In this study, we immunosuppressed mice with dexamethasone and/or cyclophosphamide then monitored the spread of viral infection into the LRT by using a noninvasive bioluminescence imaging system and a reporter Sendai virus (murine PIV type 1). Our results show that immunosuppression led to delayed viral clearance and increased viral loads in the lungs. After cessation of cyclophosphamide treatment, viral clearance occurred before the generation of Sendai-specific antibody responses and coincided with rebounds in neutrophils, T lymphocytes, and natural killer (NK) cells. Neutrophil suppression using anti-Ly6G antibody had no effect on infection clearance, NK-cell suppression using anti-NK antibody delayed clearance, and T-cell suppression using anti-CD3 antibody resulted in no clearance (chronic infection). Therapeutic use of hematopoietic growth factors G-CSF and GM-CSF had no effect on clearance of infection. In contrast, treatment with Sendai virus-specific polysera or a monoclonal antibody limited viral spread into the lungs and accelerated clearance. Overall, noninvasive bioluminescence was shown to be a useful tool to study respiratory viral progression, revealing roles for NK and T cells, but not neutrophils, in Sendai virus clearance after treatment with dexamethasone and cyclophosphamide. Virus-specific antibodies appear to have therapeutic potential.

Modification of the Tumor Microenvironment in KRAS or c-MYC-Induced Ovarian Cancer-Associated Peritonitis

The most common properties of oncogenes are cell proliferation and the prevention of apoptosis in malignant cells, which, as a consequence, induce tumor formation and dissemination. However, the effects of oncogenes on the tumor microenvironment (TME) have not yet been examined in detail. The accumulation of ascites accompanied by chronic inflammation and elevated concentrations of VEGF is a hallmark of the progression of ovarian cancer. We herein demonstrated the mechanisms by which oncogenes contribute to modulating the ovarian cancer microenvironment. c-MYC and KRAS were transduced into the mouse ovarian cancer cell line ID8. ID8, ID8-c-MYC, or ID8-KRAS cells were then injected into the peritoneal cavities of C57/BL6 mice and the production of ascites was assessed. ID8-c-MYC and ID8-KRAS both markedly accelerated ovarian cancer progression in vivo, whereas no significant differences were observed in proliferative activity in vitro. ID8-KRAS in particular induced the production of ascites, which accumulated between approximately two to three weeks after the injection, more rapidly than ID8 and ID8-c-MYC (between nine and ten weeks and between six and seven weeks, respectively). VEGF concentrations in ascites significantly increased in c-MYC-induced ovarian cancer, whereas the concentrations of inflammatory cytokines in ascites were significantly high in KRAS-induced ovarian cancer and were accompanied by an increased number of neutrophils in ascites. A cytokine array revealed that KRAS markedly induced the expression of granulocyte macrophage colony-stimulating factor (GM-CSF) in ID8 cells. These results suggest that oncogenes promote cancer progression by modulating the TME in favor of cancer progression.

GM-CSF as a therapeutic target in autoimmune diseases

Granulocyte-macrophage colony-stimulating factor (GM-CSF) has been known as a hematopoietic growth factor and immune modulator. Recent studies revealed that GM-CSF also had pro-inflammatory functions and contributed to the pathogenicity of Th17 cells in the development of Th17-mediated autoimmune diseases. GM-CSF inhibition in some animal models of autoimmune diseases showed significant beneficial effects. Therefore, several agents targeting GM-CSF are being developed and are expected to be a useful strategy for the treatment of autoimmune diseases. Particularly, in clinical trials for rheumatoid arthritis (RA) patients, GM-CSF inhibition showed rapid and significant efficacy with no serious side effects. This article summarizes recent findings of GM-CSF and information of clinical trials targeting GM-CSF in autoimmune diseases.

Neutrophils drive accelerated tumor progression in the collagen-dense mammary tumor microenvironment

Background

High mammographic density has been correlated with a 4-fold to 6-fold increased risk of developing breast cancer, and is associated with increased stromal deposition of extracellular matrix proteins, including collagen I. The molecular and cellular mechanisms responsible for high breast tissue density are not completely understood.

Methods

We previously described accelerated tumor formation and metastases in a transgenic mouse model of collagen-dense mammary tumors (type I collagen-α1 (Col1α1)^tm1Jae and mouse mammary tumor virus - polyoma virus middle T antigen (MMTV-PyVT)) compared to wild-type mice. Using ELISA cytokine arrays and multi-color flow cytometry analysis, we studied cytokine signals and the non-malignant, immune cells in the collagen-dense tumor microenvironment that may promote accelerated tumor progression and metastasis.

Results

Collagen-dense tumors did not show any alteration in immune cell populations at late stages. The cytokine signals in the mammary tumor microenvironment were clearly different between wild-type and collagen-dense tumors. Cytokines associated with neutrophil signaling, such as granulocyte monocyte-colony stimulated factor (GM-CSF), were increased in collagen-dense tumors. Depleting neutrophils with anti-Ly6G (1A8) significantly reduced the number of tumors, and blocked metastasis in over 80 % of mice with collagen-dense tumors, but did not impact tumor growth or metastasis in wild-type mice.

Conclusion

Our study suggests that tumor progression in a collagen-dense microenvironment is mechanistically different, with pro-tumor neutrophils, compared to a non-dense microenvironment.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-016-0703-7) contains supplementary material, which is available to authorized users.

Regulation of IL-17A expression in mice following subacute ozone exposure

Exposure to subacute ozone (O3) causes pulmonary neutrophil recruitment. In mice, this recruitment requires IL-17A. Ozone also causes expression of IL-23 and IL-1, which can induce IL-17A. The purpose of this study was to examine the hypothesis that IL-23 and IL-1 contribute to IL-17A expression and subsequent neutrophil recruitment after subacute O3 exposure. Wild-type, IL-23(-/-), and Flt3l(-/-) mice were exposed to air or 0.3 ppm O3 for 72 h. Flt3l(-/-) mice lack conventional dendritic cells (cDC) that can express IL-23 and IL-1. Other wild-type mice were pre-treated with saline or the IL-1R1 antagonist anakinra prior to O3 exposure. After exposure, bronchoalveolar lavage (BAL) was performed and lung tissue harvested. The results indicated that pulmonary Il17a mRNA abundance and IL-17A(+) F4/80(+) cells were significantly reduced in O3-exposed IL-23(-/-) vs in wild-type mice. In contrast, anakinra had no effect on Il23a or Il17a pulmonary mRNA abundance or on BAL concentrations of the neutrophil survival factor G-CSF, but anakinra did reduce BAL neutrophil numbers, likely because anakinra also reduced BAL IL-6. Compared to air, O3 caused a significant increase in DC numbers in wild-type, but not in Flt3(-/-) mice. However, there was no significant difference in Il23a or Il17a mRNA abundance or in BAL neutrophil count in O3-exposed Flt3(-/-) vs in wild-type mice. From these results, it was concluded that IL-23 but not IL-1 contributes to the IL-17A expression induced by subacute O3 exposure. Induction of IL-23 by O3 does not appear to require cDC.

Genome-Wide Association Study of Staphylococcus aureus Carriage in a Community-Based Sample of Mexican-Americans in Starr County, Texas

Staphylococcus aureus is the number one cause of hospital-acquired infections. Understanding host pathogen interactions is paramount to the development of more effective treatment and prevention strategies. Therefore, whole exome sequence and chip-based genotype data were used to conduct rare variant and genome-wide association analyses in a Mexican-American cohort from Starr County, Texas to identify genes and variants associated with S. aureus nasal carriage. Unlike most studies of S. aureus that are based on hospitalized populations, this study used a representative community sample. Two nasal swabs were collected from participants (n = 858) 11–17 days apart between October 2009 and December 2013, screened for the presence of S. aureus, and then classified as either persistent, intermittent, or non-carriers. The chip-based and exome sequence-based single variant association analyses identified 1 genome-wide significant region (KAT2B) for intermittent and 11 regions suggestively associated with persistent or intermittent S. aureus carriage. We also report top findings from gene-based burden analyses of rare functional variation. Notably, we observed marked differences between signals associated with persistent and intermittent carriage. In single variant analyses of persistent carriage, 7 of 9 genes in suggestively associated regions and all 5 top gene-based findings are associated with cell growth or tight junction integrity or are structural constituents of the cytoskeleton, suggesting that variation in genes associated with persistent carriage impact cellular integrity and morphology.

Nuclear-enriched abundant transcript 1 as a diagnostic and prognostic biomarker in colorectal cancer

BACKGROUND

High expression of the long non-coding RNA nuclear-enriched abundant transcript 1 (NEAT1) in whole blood has been reported in colorectal cancer patients; however, its' clinical significance and origin are unclear. We evaluated the diagnostic and prognostic value, and origin of whole blood NEAT1 in colorectal cancer.

METHODS

Expression of NEAT1 variants, NEAT1_v1 and NEAT1_v2 were determined using real-time quantitative PCR. The diagnostic value of whole blood NEAT1 expression was evaluated in test (n = 60) and validation (n = 200) cohorts of colorectal cancer patients and normal controls (NCs). To identify the origin of NEAT1, its expression was analyzed in blood, matched primary tumor tissues, para-tumor tissues, metastatic tissues, and also immune cells from patients or NCs. Function of NEAT1 in colorectal cell lines was also assessed. The correlation of NEAT1 expression with clinical outcomes was assessed in 191 patients.

RESULTS

Whole blood NEAT1 expression was significantly higher in colorectal cancer patients than in NCs. NEAT1_v1 and NEAT1_v2 expression were highly accurate in distinguishing colorectal cancer patients from NCs (area under the curve: 0.787 and 0.871, respectively). Knockdown of NEAT1_v1 in vitro could inhibit cell invasion and proliferation, while knockdown of NEAT1_v2 promoted cell growth. However, whole blood expression was not correlated with matched tissues. An elevated expression was seen in neutrophils from CRC patients. Furthermore, high expression of NEAT1_v1 was correlated with worse overall survival. In contrast, high expression of NEAT1_v2 alone was correlated with better overall survival.

CONCLUSION

Whole blood NEAT1 expression is a novel diagnostic and prognostic biomarker of overall survival in colorectal cancer. Elevated NEAT1 may derive from neutrophils.

Preclinical characterisation of the GM-CSF receptor as a therapeutic target in rheumatoid arthritis

OBJECTIVE

Previous work has suggested that the granulocyte macrophage colony stimulating factor (GM-CSF)-GM-CSF receptor α axis (GM-CSFRα) may provide a new therapeutic target for the treatment of rheumatoid arthritis (RA). Therefore, we investigated the cellular expression of GM-CSFRα in RA synovial tissue and investigated the effects of anti-GM-CSFRα antibody treatment in vitro and in vivo in a preclinical model of RA.

METHODS

We compared GM-CSFRα expression on macrophages positive for CD68 or CD163 on synovial biopsy samples from patients with RA or psoriatic arthritis (PsA) to disease controls. In addition, we studied the effects of CAM-3003, an anti-GM-CSFR antibody in a collagen induced arthritis model of RA in DBA/1 mice. The pharmacokinetic profile of CAM-3003 was studied in naïve CD1(ICR) mice (see online supplement) and used to interpret the results of the pharmacodynamic studies in BALB/c mice.

RESULTS

GM-CSFRα was expressed by CD68 positive and CD163 positive macrophages in the synovium, and there was a significant increase in GM-CSFRα positive cells in patients in patients with RA as well as patients with PsA compared with patients with osteoarthritis and healthy controls. In the collagen induced arthritis model there was a dose dependent reduction of clinical arthritis scores and the number of F4/80 positive macrophages in the inflamed synovium after CAM-3003 treatment. In BALB/c mice CAM-3003 inhibited recombinant GM-CSF mediated margination of peripheral blood monocytes and neutrophils.

CONCLUSIONS

The findings support the ongoing development of therapies aimed at interfering with GM-CSF or its receptor in various forms of arthritis, such as RA and PsA.

Effect of AcHERV-GmCSF as an Influenza Virus Vaccine Adjuvant

Introduction

The first identification of swine-originated influenza A/CA/04/2009 (pH1N1) as the cause of an outbreak of human influenza accelerated efforts to develop vaccines to prevent and control influenza viruses. The current norm in many countries is to prepare influenza vaccines using cell-based or egg-based killed vaccines, but it is difficult to elicit a sufficient immune response using this approach. To improve immune responses, researchers have examined the use of cytokines as vaccine adjuvants, and extensively investigated their functions as chemoattractants of immune cells and boosters of vaccine-mediated protection. Here, we evaluated the effect of Granulocyte-macrophage Colony-Stimulating Factor (GmCSF) as an influenza vaccine adjuvant in BALB/c mice.

Method and Results

Female BALB/c mice were immunized with killed vaccine together with a murine GmCSF gene delivered by human endogenous retrovirus (HERV) envelope coated baculovirus (1×10⁷ FFU AcHERV-GmCSF, i.m.) and were compared with mice immunized with the killed vaccine alone. On day 14, immunized mice were challenged with 10 median lethal dose of mouse adapted pH1N1 virus. The vaccination together with GmCSF treatment exerted a strong adjuvant effect on humoral and cellular immune responses. In addition, the vaccinated mice together with GmCSF were fully protected against infection by the lethal influenza pH1N1 virus.

Conclusion

Thus, these results indicate that AcHERV-GmCSF is an effective molecular adjuvant that augments immune responses against influenza virus.

Staphylococcal enterotoxin A regulates bone marrow granulocyte trafficking during pulmonary inflammatory disease in mice

Pulmonary neutrophil infiltration produced by Staphylococcal enterotoxin A (SEA) airway exposure is accompanied by marked granulocyte accumulation in bone marrow (BM). Therefore, the aim of this study was to investigate the mechanisms of BM cell accumulation, and trafficking to circulating blood and lung tissue after SEA airway exposure. Male BALB/C mice were intranasally exposed to SEA (1μg), and at 4, 12 and 24h thereafter, BM, circulating blood, bronchoalveolar lavage (BAL) fluid and lung tissue were collected. Adhesion of BM granulocytes and flow cytometry for MAC-1, LFA1-α and VLA-4 and cytokine and/or chemokine levels were assayed after SEA-airway exposure. Prior exposure to SEA promoted a marked PMN influx to BAL and lung tissue, which was accompanied by increased counts of immature and/or mature neutrophils and eosinophils in BM, along with blood neutrophilia. Airway exposure to SEA enhanced BM neutrophil MAC-1 expression, and adhesion to VCAM-1 and/or ICAM-1-coated plates. Elevated levels of GM-CSF, G-CSF, INF-γ, TNF-α, KC/CXCL-1 and SDF-1α were detected in BM after SEA exposure. SEA exposure increased production of eosinopoietic cytokines (eotaxin and IL-5) and BM eosinophil VLA-4 expression, but it failed to affect eosinophil adhesion to VCAM-1 and ICAM-1. In conclusion, BM neutrophil accumulation after SEA exposure takes place by integrated action of cytokines and/or chemokines, enhancing the adhesive responses of BM neutrophils and its trafficking to lung tissues, leading to acute lung injury. BM eosinophil accumulation in SEA-induced acute lung injury may occur via increased eosinopoietic cytokines and VLA-4 expression.

Influenza induces IL-8 and GM-CSF secretion by human alveolar epithelial cells through HGF/c-Met and TGF-α/EGFR signaling

The most severe complication of influenza is viral pneumonia, which can lead to the acute respiratory distress syndrome. Alveolar epithelial cells (AECs) are the first cells that influenza virus encounters upon entering the alveolus. Infected epithelial cells produce cytokines that attract and activate neutrophils and macrophages, which in turn induce damage to the epithelial-endothelial barrier. Hepatocyte growth factor (HGF)/c-Met and transforming growth factor-α (TGF-α)/epidermal growth factor receptor (EGFR) are well known to regulate repair of damaged alveolar epithelium by stimulating cell migration and proliferation. Recently, TGF-α/EGFR signaling has also been shown to regulate innate immune responses in bronchial epithelial cells. However, little is known about whether HGF/c-Met signaling alters the innate immune responses and whether the innate immune responses in AECs are regulated by HGF/c-Met and TGF-α/EGFR. We hypothesized that HGF/c-Met and TGF-α/EGFR would regulate innate immune responses to influenza A virus infection in human AECs. We found that recombinant human HGF (rhHGF) and rhTGF-α stimulated primary human AECs to secrete IL-8 and granulocyte macrophage colony-stimulating factor (GM-CSF) strongly and IL-6 and monocyte chemotactic protein 1 moderately. Influenza infection stimulated the secretion of IL-8 and GM-CSF by AECs plated on rat-tail collagen through EGFR activation likely by TGF-α released from AECs and through c-Met activated by HGF secreted from lung fibroblasts. HGF secretion by fibroblasts was stimulated by AEC production of prostaglandin E₂ during influenza infection. We conclude that HGF/c-Met and TGF-α/EGFR signaling enhances the innate immune responses by human AECs during influenza infections.

GM-CSF as a target in inflammatory/autoimmune disease: current evidence and future therapeutic potential

Granulocyte-macrophage colony-stimulating factor (GM-CSF) can be viewed as a pro-inflammatory cytokine rather than as a key regulator of steady state and systemic myelopoiesis. Key aspects of GM-CSF biology need to be clarified such as pro-survival vs activation/differentiation function, its cellular sources, its responsive cell populations, its downstream mediators/pathways, and when GM-CSF is relevant. Striking effects of GM-CSF depletion/deletion in some pre-clinical autoimmune/inflammation models have been reported. Systemic effects of administered GM-CSF are not necessarily informative about its local blockade in disease. Recent clinical RA trials, particularly Phase II trials with mavrilimumab (anti-GM-CSFRα Ab), show rapid and impressive efficacy with no significant adverse effects. Larger and longer trials targeting GM-CSF are needed and with careful monitoring of unwanted side effects. This review summarizes the most recent information on these topics.

Chronic ethanol feeding increases the severity of Staphylococcus aureus skin infections by altering local host defenses

Alcoholics are at increased risk of Staphylococcus aureus skin infection and serious sequelae, such as bacteremia and death. Despite the association between alcoholism and severe S. aureus skin infection, the impact of EtOH on anti-S. aureus cutaneous immunity has not been investigated in a model of chronic EtOH exposure. To test the hypothesis that EtOH enhances the severity of S. aureus skin infection, mice were fed EtOH for ≥12 weeks via the Meadows-Cook model of alcoholism and inoculated with S. aureus following epidermal abrasion. Evidence of exacerbated staphylococcal disease in EtOH-fed mice included: skin lesions that were larger and contained more organisms, greater weight loss, and increased bacterial dissemination. Infected EtOH-fed mice demonstrated poor maintenance and induction of PMN responses in skin and draining LNs, respectively. Additionally, altered PMN dynamics in the skin of these mice corresponded with reduced production of IL-23 and IL-1β by CD11b(+) myeloid cells and IL-17 production by γδ T cells, with the latter defect occurring in the draining LNs as well. In addition, IL-17 restoration attenuated S. aureus-induced dermatopathology and improved bacterial clearance defects in EtOH-fed mice. Taken together, the findings show, in a novel model system, that the EtOH-induced increase in S. aureus-related injury/illness corresponds with defects in the IL-23/IL-17 inflammatory axis and poor PMN accumulation at the site of infection and draining LNs. These findings offer new information about the impact of EtOH on cutaneous host-defense pathways and provide a potential mechanism explaining why alcoholics are predisposed to S. aureus skin infection.

Metabolic modeling of muscle metabolism identifies key reactions linked to insulin resistance phenotypes

Objective

Dysregulated muscle metabolism is a cardinal feature of human insulin resistance (IR) and associated diseases, including type 2 diabetes (T2D). However, specific reactions contributing to abnormal energetics and metabolic inflexibility in IR are unknown.

Methods

We utilize flux balance computational modeling to develop the first systems-level analysis of IR metabolism in fasted and fed states, and varying nutrient conditions. We systematically perturb the metabolic network to identify reactions that reproduce key features of IR-linked metabolism.

Results

While reduced glucose uptake is a major hallmark of IR, model-based reductions in either extracellular glucose availability or uptake do not alter metabolic flexibility, and thus are not sufficient to fully recapitulate IR-linked metabolism. Moreover, experimentally-reduced flux through single reactions does not reproduce key features of IR-linked metabolism. However, dual knockdowns of pyruvate dehydrogenase (PDH), in combination with reduced lipid uptake or lipid/amino acid oxidation (ETFDH), does reduce ATP synthesis, TCA cycle flux, and metabolic flexibility. Experimental validation demonstrates robust impact of dual knockdowns in PDH/ETFDH on cellular energetics and TCA cycle flux in cultured myocytes. Parallel analysis of transcriptomic and metabolomics data in humans with IR and T2D demonstrates downregulation of PDH subunits and upregulation of its inhibitory kinase PDK4, both of which would be predicted to decrease PDH flux, concordant with the model.

Conclusions

Our results indicate that complex interactions between multiple biochemical reactions contribute to metabolic perturbations observed in human IR, and that the PDH complex plays a key role in these metabolic phenotypes.

Role of GM-CSF in the inflammatory cytokine network that regulates neutrophil influx into the colonic mucosa during Clostridium difficile infection in mice

Clostridium difficile infection in antibiotic-treated mice results in acute colitis characterized by severe intestinal histopathology, robust neutrophil influx, and increased expression of numerous inflammatory cytokines, including GM-CSF. We utilized a neutralizing monoclonal antibody (mAb) against GM-CSF in a murine model to study the role of GM-CSF during acute C. difficile colitis. Cefoperazone-treated mice were challenged with C. difficile (strain 630) spores. Expression of GM-CSF was significantly increased in animals challenged with C. difficile. Treatment with an anti-GM-CSF mAb did not alter C. difficile colonization levels, weight loss, or expression of IL-22 and RegIIIγ. However, expression of the inflammatory cytokines TNFα and IL-1β, as well as iNOS, was significantly reduced following anti-GM-CSF treatment. Expression of the neutrophil chemokines CXCL1 and CXCL2, but not the chemokines CCL2, CCL4, CXCL9, and CXCL10, was significantly reduced by anti-GM-CSF treatment. Consistent with a decrease in neutrophil-attractant chemokine expression, there were fewer neutrophils in histology sections and a reduction in the expression of secretory leukocyte protease inhibitor (SLPI), a tissue anti-protease that protects against damage by secreted neutrophil elastase. These data indicate that GM-CSF plays a role in the inflammatory signaling network that drives neutrophil recruitment in response to C. difficile infection but does not appear to play a role in clearance of the infection.

Preceding human metapneumovirus infection increases adherence of Streptococcus pneumoniae and severity of murine pneumococcal pneumonia

BACKGROUND

Coinfection with respiratory virus and Streptococcus pneumoniae has been frequently reported in several epidemiologic studies. The aim of this study was to explore the effect of preceding human metapneumovirus (hMPV) inoculation on subsequent pneumococcal infection.

METHODS

Hep-2 and A549 cells were infected with hMPV then inoculated with S. pneumoniae. Bacterial adhesion was measured using colony forming unit and cytometric-fluorescence assays. In vivo bacterial adhesion was examined in hMPV-infected mice after inoculation of fluorescence-conjugated S. pneumoniae. Pulmonary inflammation (bacterial titers, cytokine levels, and histopathology) of hMPV-infected mice was investigated after inoculation with S. pneumoniae.

RESULTS

In vitro results of bacterial infection with S. pneumoniae on A549 and Hep-2 monolayer cells showed that even though cellular adherence was variable among different serotypes, there was significantly enhanced bacterial adherence in A549 cells with preceding hMPV infection. In addition, in vivo study of hMPV-infected mice showed increased adhesion of S. pneumoniae on the bronchial epithelium with delayed bacterial clearance and exacerbated histopathology. Furthermore, mice with preceding hMPV infection showed repressed recruitment of airway neutrophils with decreased expression of neutrophil chemoattractants during pneumococcal infection.

CONCLUSION

These results suggest that hMPV-infected airway cells, especially the lower airway epithelium, express increased adherence with S. pneumoniae. Furthermore, hMPV-infected mice showed impaired recruitment of airway neutrophils, possibly leading to delayed bacterial clearance and exacerbated pulmonary inflammation, after secondary infection with pneumococcal isolates.

Granulocyte macrophage colony-stimulating factor and the intestinal innate immune cell homeostasis in Crohn's disease

Current literature consolidates the view of Crohn's disease (CD) as a form of immunodeficiency highlighting dysregulation of intestinal innate immunity in the pathogenesis of CD. Intestinal macrophages derived from blood monocytes play a key role in sustaining the innate immune homeostasis in the intestine, suggesting that the monocyte/macrophage compartment might be an attractive therapeutic target for the management of CD. Granulocyte macrophage colony-stimulating factor (GM-CSF) is a hematopoietic growth factor that also promotes myeloid cell activation, proliferation, and differentiation. GM-CSF has a protective effect in human CD and mouse models of colitis. However, the role of GM-CSF in immune and inflammatory reactions in the intestine is not well defined. Beneficial effects exerted by GM-CSF during intestinal inflammation could relate to modulation of the mucosal barrier function in the intestine, including epithelial cell proliferation, survival, restitution, and immunomodulatory actions. The aim of this review is to summarize potential mechanistic roles of GM-CSF in intestinal innate immune cell homeostasis and to highlight its central role in maintenance of the intestinal immune barrier in the context of immunodeficiency in CD.