Progranulin aggravates lethal Candida albicans sepsis by regulating inflammatory response and antifungal immunity.

Candida albicans is the most frequent pathogen of fungal sepsis associated with substantial mortality in critically ill patients and those who are immunocompromised. Identification of novel immune-based therapeutic targets from a better understanding of its molecular pathogenesis is required. Here, we reported that the production of progranulin (PGRN) levels was significantly increased in mice after invasive C.albicans infection. Mice that lacked PGRN exhibited attenuated kidney injury and increased survival upon a lethal systemic infection with C. albicans. In mice, PGRN deficiency protected against systemic candidiasis by decreasing aberrant inflammatory reactions that led to renal immune cell apoptosis and kidney injury, and by enhancing antifungal capacity of macrophages and neutrophils that limited fungal burden in the kidneys. PGRN in hematopoietic cell compartment was important for this effect. Moreover, anti-PGRN antibody treatment limited renal inflammation and fungal burden and prolonged survival after invasive C. albicans infection. In vitro, PGRN loss increased phagocytosis, phagosome formation, reactive oxygen species production, neutrophil extracellular traps release, and killing activity in macrophages or neutrophils. Mechanistic studies demonstrated that PGRN loss up-regulated Dectin-2 expression, and enhanced spleen tyrosine kinase phosphorylation and extracellular signal-regulated kinase activation in macrophages and neutrophils. In summary, we identified PGRN as a critical factor that contributes to the immunopathology of invasive C.albicans infection, suggesting that targeting PGRN might serve as a novel treatment for fungal infection.

The preprogrammed anti-inflammatory phenotypes of CD11chigh macrophages by Streptococcus pneumoniae aminopeptidase N safeguard from allergic asthma.

BACKGROUND: Early microbial exposure is associate with protective allergic asthma. We have previously demonstrated that Streptococcus pneumoniae aminopeptidase N (PepN), one of the pneumococcal components, inhibits ovalbumin (OVA) -induced airway inflammation in murine models of allergic asthma, but the underlying mechanism was incompletely determined. METHODS: BALB/c mice were pretreated with the PepN protein and exposed intranasally to HDM allergen. The anti-inflammatory mechanisms were investigated using depletion and adoptive transfer experiments as well as transcriptome analysis and isolated lung CD11chigh macrophages. RESULTS: We found pretreatment of mice with PepN promoted the proliferation of lung-resident F4/80+CD11chigh macrophages in situ but also mobilized bone marrow monocytes to infiltrate lung tissue that were then transformed into CD11high macrophages. PepN pre-programmed the macrophages during maturation to an anti-inflammatory phenotype by shaping the metabolic preference for oxidative phosphorylation (OXPHOS) and also inhibited the inflammatory response of macrophages by activating AMP-activated protein kinase. Furthermore, PepN treated macrophages also exhibited high-level costimulatory signaling molecules which directed the differentiation into Treg. CONCLUSION: Our results demonstrated that the expansion of CD11chigh macrophages in lungs and the OXPHOS metabolic bias of macrophages are associated with reduced allergic airway inflammation after PepN exposure, which paves the way for its application in preventing allergic asthma.

Identification of cis-acting elements upstream of regR gene in streptococcus pneumoniae.

The identification and characterization of functional cis-acting elements is of fundamental importance for comprehending the regulatory mechanisms of gene transcription and bacterial pathogenesis. The transcription factor RegR has been demonstrated to control both competence and virulence in Streptococcus pneumoniae. Despite the clear contribution of RegR to these pathways, the mechanisms underlying its transcriptional regulation remain poorly understood. In this study, we conducted mutational analysis, gene dissection and luciferase activity assays to characterize the cis-elements situated upstream of the regR gene. Our findings revealed that a 311 bp 3'-terminal DNA sequence of the spd0300 gene represents a central region of the upstream cis-acting element of regR. Further investigations identified two structurally similar enhancer-like sequences within this region which feature prominently in the regulation of regR transcription. Furthermore, employing DNA pull-down assays allowed us to enrich the trans-acting factors with the potential to interact with these cis-acting elements. Notably, we found that the competence regulator ComE was implicated in the regulation of regR transcription, a finding which was corroborated by electrophoretic mobility shift assays (EMSA) and quantitative real-time PCR analyses (qRT-PCR). Taken together, our data thus provide fresh insight into the transcriptional regulation of regR.

Glucose levels affect MgaSpn regulation on the virulence and adaptability of Streptococcus pneumoniae.

Streptococcus pneumoniae can regulate virulence gene expression by sensing environmental changes, which is key to its pathogenicity. The global transcription regulator MgaSpn of Streptococcus pneumoniae regulates virulence genes expression by directly binding to the promoter regions, but its role in response to different environments remains unclear. In this study, we found that glucose levels could affect phosphocholine content, which was mediated by MgaSpn. MgaSpn can also alter its anti-phagocytosis ability, depending on the availability of glucose. In addition, transcriptome analysis of wild-type D39s in low and high glucose concentrations revealed that MgaSpn was also involved in the regulation of carbon metabolism inhibition (carbon catabolite repression; CCR) and translation processes, which made S. pneumoniae highly competitive in fluctuating environments. In conclusion, MgaSpn is closely related to the virulence and environmental adaptability of Streptococcus pneumoniae.

CCL3 aggravates intestinal damage in NEC by promoting macrophage chemotaxis and M1 macrophage polarization.

BACKGROUND: NEC is a life-threatening gastrointestinal disease in neonates, the pathogenesis of which remains poorly understood. METHODS: CCL3 levels in intestinal tissue of mice were measured and analyzed. HE staining was used to assess pathological changes in intestinal tissue. FCM was used to detect the proportion and phenotype of macrophages. RNA-seq and RT-PCR were used to evaluate the effect of CCL3 on macrophages. RESULTS: CCL3 was highly expressed in the intestinal tissues of mice with NEC and induced macrophage infiltration. Transcriptome data showed that CCL3 strongly induced a transition in the phenotype of macrophages into a proinflammatory one. Mechanistically, in vivo experiments confirmed that CCL3 induced M1 macrophage polarization in NEC intestinal tissue, thereby aggravating inflammatory injury of intestinal tissue, which was alleviated by anti-CCL3 treatment. In addition, in vitro experiments showed that CCL3 significantly enhances the expression of M1-related genes in both PMφ and BMDM while inhibiting the expression of M2-related genes, which was also alleviated by anti-CCl3 treatment. CONCLUSIONS: Our data elucidated the involvement of CCL3 in the pathogenesis of NEC, in which upregulated CCL3 expression exacerbated inflammatory intestinal damage by regulating macrophage chemotaxis and M1 phenotype polarization, suggesting that blocking CCL3 may be a potential strategy for effective intervention in NEC. IMPACT: Our study represents an important conceptual advancement that CCL3 may be one of the key culprits of intestinal tissue damage in patients with NEC. CCL3 aggravates inflammatory intestinal injury and intestinal mucosal barrier imbalance by regulating the chemotaxis, polarization, and function of macrophages. Blocking CCL3 significantly reduced NEC-mediated intestinal injury, suggesting a new potential therapeutic strategy.

CD5L attenuates allergic airway inflammation by expanding CD11chigh alveolar macrophages and inhibiting NLRP3 inflammasome activation via HDAC2.

Allergic asthma is an airway inflammatory disease dominated by type 2 immune responses and there is currently no curative therapy for asthma. CD5-like antigen (CD5L) has been known to be involved in a variety of inflammatory diseases. However, the role of CD5L in allergic asthma remains unclear. In the present study, mice were treated with recombinant CD5L (rCD5L) during house dust mite (HDM) and ovalbumin (OVA) challenge to determine the role of CD5L in allergic asthma, and the underlying mechanism was further explored. Compared with PBS group, serum CD5L levels of asthmatic mice were significantly decreased, and the levels of CD5L in lung tissues and bronchoalveolar lavage fluid (BALF) were significantly increased. CD5L reduced airway inflammation and Th2 immune responses in asthmatic mice. CD5L exerted its anti-inflammatory function by increasing CD11chigh alveolar macrophages (CD11chigh AMs), and the anti-inflammatory role of CD11chigh AMs in allergic asthma was confirmed by CD11chigh AMs depletion and transfer assays. In addition, CD5L increased the CD5L+ macrophages and inhibited NLRP3 inflammasome activation by increasing HDAC2 expression in lung tissues of asthmatic mice. Hence, our study implicates that CD5L has potential usefulness for asthma treatment.

Identifying Prokineticin2 as a Novel Immunomodulatory Factor in Diagnosis and Treatment of Sepsis.

OBJECTIVES: Sepsis remains a highly lethal disease, whereas the precise reasons for death remain poorly understood. Prokineticin2 is a secreted protein that regulates diverse biological processes. Whether prokineticin2 is beneficial or deleterious to sepsis and the underlying mechanisms remain unknown. DESIGN: Prospective randomized animal investigation and in vitro studies. SETTING: Research laboratory at a medical university hospital. SUBJECTS: Prokineticin2 deficiency and wild-type C57BL/6 mice were used for in vivo studies; sepsis patients by Sepsis-3 definitions, patient controls, and healthy controls were used to obtain blood for in vitro studies. INTERVENTIONS: Prokineticin2 concentrations were measured and analyzed in human septic patients, patient controls, and healthy individuals. The effects of prokineticin2 on sepsis-related survival, bacterial burden, organ injury, and inflammation were assessed in an animal model of cecal ligation and puncture-induced polymicrobial sepsis. In vitro cell models were also used to study the role of prokineticin2 on antibacterial response of macrophages. MEASUREMENTS AND MAIN RESULTS: Prokineticin2 concentration is dramatically decreased in the patients with sepsis and septic shock compared with those of patient controls and healthy controls. Furthermore, the prokineticin2 concentration in these patients died of sepsis or septic shock is significantly lower than those survival patients with sepsis or septic shock, indicating the potential value of prokineticin2 in the diagnosis of sepsis and septic shock, as well as the potential value in predicting mortality in adult patients with sepsis and septic shock. In animal model, recombinant prokineticin2 administration protected against sepsis-related deaths in both heterozygous prokineticin2 deficient mice and wild-type mice and alleviated sepsis-induced multiple organ damage. In in vitro cell models, prokineticin2 enhanced the phagocytic and bactericidal functions of macrophage through signal transducers and activators of transcription 3 pathway which could be abolished by signal transducers and activators of transcription 3 inhibitors S3I-201. Depletion of macrophages reversed prokineticin2-mediated protection against polymicrobial sepsis. CONCLUSIONS: This study elucidated a previously unrecognized role of prokineticin2 in clinical diagnosis and treatment of sepsis. The proof-of-concept study determined a central role of prokineticin2 in alleviating sepsis-induced death by regulation of macrophage function, which presents a new strategy for sepsis immunotherapy.

Interleukin-4 protects mice against lethal influenza and Streptococcus pneumoniae co-infected pneumonia.

Streptococcus pneumoniae co-infection post-influenza is a major cause of mortality characterized by uncontrolled bacteria burden and excessive immune response during influenza pandemics. Interleukin (IL)-4 is a canonical type II immune cytokine known for its wide range of biological activities on different cell types. It displays protective roles in numerous infectious diseases and immune-related diseases, but its role in influenza and S. pneumoniae (influenza/S. pneumoniae) co-infected pneumonia has not been reported. In our study, we used C57BL/6 wild-type (WT) and IL-4-deficient (IL-4-/- ) mice to establish co-infection model with S. pneumoniae after influenza virus infection. Co-infected IL-4-/- mice showed increased mortality and weight loss compared with WT mice. IL-4 deficiency led to increased bacterial loads in lungs without altering influenza virus replication, suggesting a role of IL-4 in decreasing post-influenza susceptibility to S. pneumoniae co-infection. Loss of IL-4 also resulted in aggravated lung damage together with massive proinflammatory cytokine production and immune cell infiltration during co-infection. Administration of recombinant IL-4 rescued the survival and weight loss of IL-4-/- mice in lethal co-infection. Additionally, IL-4 deficiency led to more immune cell death in co-infection. Gasdermin D (GSDMD) during co-infection was induced in IL-4-/- mice that subsequently activated cell pyroptosis. Treatment of recombinant IL-4 or inhibition of GSDMD activity by disulfiram decreased immune cell death and bacterial loads in lungs of IL-4-/- co-infected mice. These results suggest that IL-4 decreases post-influenza susceptibility to S. pneumoniae co-infection via suppressing GSDMD-induced pyroptosis. Collectively, this study demonstrates the protective role of IL-4 in influenza/S. pneumoniae co-infected pneumonia.

TLR4 regulates ROS and autophagy to control neutrophil extracellular traps formation against Streptococcus pneumoniae in acute otitis media.

BACKGROUND: Otitis media (OM), a prevalent pediatric infectious disease, is mainly caused by Streptococcus pneumoniae (S.pn). Neutrophil extracellular traps (NETs), a novel antimicrobial strategy, were reported in 2004. We found that NETs formed in the middle ear with acute otitis media (AOM) induced by S.pn. However, the mechanisms of NETs formation are not entirely clear. METHODS: We stimulated neutrophils isolated from mouse bone marrow with S.pn clinical stain 19F in vitro, and established mouse model of AOM via transbullar injection with S.pn. NETs formation, reactive oxygen species (ROS) production, autophagy activation and bacterial load were analyzed in TLR4-/- and wild-type neutrophils stimulated in vitro with S.pn and in vivo during AOM. RESULTS: We found that autophagy and ROS were required for S.pn-induced NETs formation. Moreover, TLR4 partly mediated NETs formation in response to S.pn in vitro and in vivo during AOM. We also showed that attenuated NETs formation in TLR4-/- neutrophils correlated with an impaired ROS production and autophagy activation in vitro and in vivo. In addition, both the in vivo and in vitro-produced NETs were able to engulf and kill S.pn. CONCLUSIONS: TLR4 regulates ROS and autophagy to control NETs formation against S.pn in the course of AOM. IMPACT: S.pn can induce NETs formation in vitro and in vivo; TLR4 regulates NETs formation by ROS and autophagy; NETs contribute to the clearance of bacteria in acute otitis media. In this study, we firstly found that autophagy and ROS were required for S.pn-induced NETs formation in the model of acute otitis media (AOM). And to some extent, TLR4 mediated NETs formation during AOM. Our research might provide a potential strategy for the treatment of otitis media.

Progranulin Decreases Susceptibility to Streptococcus pneumoniae in Influenza and Protects against Lethal Coinfection.

Streptococcus pneumoniae coinfection is a major cause of mortality in influenza pandemics. Growing evidence shows that uncontrolled immune response results in severe tissue damage and thereby promotes death in coinfection. Progranulin (PGRN) is widely expressed in immune and epithelial cells and exerts anti-inflammatory role in many diseases. We found that PGRN levels were significantly elevated in clinical influenza/S. pneumoniae-coinfected patients. C57BL/6 wild-type (WT) and PGRN-deficient (PGRN-/-) mice were infected with influenza virus PR8 and then superchallenged with S. pneumoniae serotype 19F. Coinfected PGRN-/- mice showed increased mortality and weight loss compared with WT mice. PGRN deficiency led to increased bacterial loads in lungs without altering influenza virus replication, suggesting a role of PGRN in decreasing postinfluenza susceptibility to S. pneumoniae coinfection. Administration of recombinant PGRN improved survival of WT and PGRN-/- mice in lethal coinfection. Additionally, loss of PGRN resulted in aggravated lung damage along with massive proinflammatory cytokine production and immune cell infiltration during coinfection. Endoplasmic reticulum stress (ERS) during influenza, and coinfection was strongly induced in PGRN-/- mice that subsequently activated apoptosis signaling pathways. Treatment of recombinant PGRN or inhibition of ERS by 4-phenylbutyrate decreased apoptosis and bacterial loads in lungs of coinfected mice. These results suggest that PGRN decreases postinfluenza susceptibility to S. pneumoniae coinfection via suppressing ERS-mediated apoptosis. Impaired bacterial clearance and increased lung inflammation are associated with the lethal outcome of coinfected PGRN-/- mice. Our study provides therapeutic implication of PGRN to reduce morbidity and mortality in influenza/S. pneumoniae coinfection.

IL-27 Negatively Controls Antifungal Activity in a Model of Invasive Pulmonary Aspergillosis.

Invasive pulmonary aspergillosis is a life-threatening disease, particularly in immunocompromised patients, despite currently available therapy. IL-27 is an important regulatory cytokine in infection and immunity. However, its role in the pathogenesis of invasive pulmonary aspergillosis remains unknown. Here we found that Aspergillus fumigatus pulmonary infection induced an elevated production of IL-27 in the lung. As compared with wild-type (WT) mice, IL-27R (IL-27 receptor)-deficient mice developed less severe infection when challenged with A. fumigatus conidia, as evidenced by the decreased fungal colonization and pathology of lungs and the increased survival. IL-27R deficiency led to significantly higher production of IFN-γ in the lung after A. fumigatus infection, and the increased resistance to invasive pulmonary A. fumigatus infection in IL-27R-deficient mice was ablated by neutralizing IFN-γ. Importantly, neutralization of IL-27 could protect WT mice against invasive pulmonary A. fumigatus infection. Our data therefore suggest an important role of IL-27 in impairing anti-A. fumigatus host immunity, which may have translational implications in treating clinical cases of invasive pulmonary aspergillosis.

Progranulin as a novel biomarker in diagnosis of early-onset neonatal sepsis.

BACKGROUND: Infections are leading causes of morbidity and mortality in neonates and may also have severe long-term consequences. As early diagnosis of neonatal sepsis improves prognosis, identification of new or complementary biomarkers is of great importance. In this study, we have evaluated the diagnostic value of progranulin (PGRN) in early-onset neonatal sepsis (EOS) and compare its effectiveness with other commonly used biomarkers, such as procalcitonin (PCT) and C-reactive protein (CRP). METHODS: A total of 121 infants with gestational age of >34 weeks admitted with suspected EOS were included in this study. Before initiating therapy, blood samples for whole blood count, CRP, PCT and PGRN were obtained from all neonates. Receiver-operating characteristic (ROC) curve and multivariate logistic regression analyses were performed. RESULTS: Serum PGRN level of infected group was significantly higher than uninfected group (median 47.72 vs. 37.86 ng/ml, respectively; Mann-Whitney p < 0.0001). The ROC area under the curve (AUC) was 0.786 [95% confidence interval (CI) 0.706-0.867; p < 0.0001] for PGRN, 0.699 (95% CI 0.601-0.797; p = 0.0001) for age adjusted PCT, and 0.673 (95% CI 0.573-0.773; p = 0.0007) for CRP. With a cut-off value of 37.89 ng/ml, the diagnostic sensitivity and negative predictive value of PGRN were 94.34% and 91.7%, respectively. PGRN could significantly predict EOS independently of PCT (p < 0.0001), and the combined use of PGRN and PCT could significantly improve diagnostic performance for EOS (0.806; 95% CI 0.73-0.88; p < 0.0001), with a specificity of 89.06% and a positive predictive value of 81.10%. CONCLUSIONS: PGRN may be used as a promising biomarker for the diagnosis of EOS, and the combined use of PGRN and PCT could improve the diagnosis of sepsis.

Cytosolic mtDNA released from pneumolysin-damaged mitochondria triggers IFN-ß production in epithelial cells.

Pneumolysin (Ply) is a major virulence factor of Streptococcus pneumoniae. Ply-induced interferon-ß (IFN-ß) expression in host macrophages has been shown to be due to the accumulation of mitochondrial deoxyribonucleic acid (mtDNA) in the cytoplasm during S. pneumoniae infection. Our findings extend this work to show human bronchial epithelial cells that reside at the interface of inflammatory injury, BEAS-2B, adapt to local cues by altering mitochondrial states and releasing excess mtDNA. The results in this research showed that purified Ply induced the expression of IFN-ß in human epithelial cells, which was accompanied by mitochondrial damage both in vivo and in vitro. The observations also were supported by the increased mtDNA concentrations in the bronchial lavage fluid of mice infected with S. pneumoniae. In summary, our study demonstrated that Ply triggered the production of IFN-ß in epithelial cells, and this response was mediated by mtDNA released from Ply-damaged mitochondria. It displayed an impressive modulation of IFN-ß response to S. pneumoniae in epithelial cells.

Detection of B-type natriuretic peptide by establishing a low-cost and replicable fluorescence resonance energy transfer platform.

Aiming at the establishment of a sensitive and specific diagnostic method for early heart failure (HF), we developed a cost-effective fluorescence resonance energy transfer (FRET) platform for the detection of B-type natriuretic peptide (BNP), a characteristic biomarker of HF. Graphene oxide (GO) was selected as the FRET receptor in view of its advantages including commercial availability, low-cost and chemical stability, and dye-modified aptamer was used as the energy donor of FRET as well as in charge of the specific recognition of BNP. Based on the ON (strong emission) and OFF (quenching) states of FRET in the presence and absence of BNP, respectively, specific detection of BNP was achieved in the range 0.074-0.56 pg/mL with a limit of detection as low as 45 fg/mL (3σ). This FRET platform was applied to detect BNP in 45 blood samples to demonstrate its practicability in clinical diagnosis. Compared to the commonly used Siemens method (chemiluminescence immunoassay, CLIA) in hospital, our approach is more accurate and specific for HF diagnosis with areas under the receiver operating characteristic curves of 0.869 (95% CI 0.733-1.00, P < 0.05) vs 0.850 (95% CI 0.703-0.997, P < 0.05) and specificity of 68.8% vs 65.6%. This platform is promising in early diagnosis of HF through ultrasensitive and specific detection of BNP. Graphical abstract To solve the clinical diagnostic problem for early heart failure (HF) which lacks sensitivity and specificity, we established a cost-effective and rapid fluorescence analysis method based on fluorescence resonance energy transfer (FRET) platform for the detection of B-type natriuretic peptide (BNP), a characteristic biomarker of HF.

Nontypeable Haemophilus influenzae DNA stimulates type I interferon expression via STING signaling pathway.

Nontypeable Haemophilus influenzae (NTHI) is one of the leading causes of acute exacerbations of COPD (AECOPD). Although the immunoregulation function of NTHI outer member protein and endotoxin were confirmed, the role of NTHI DNA in activating immune responses remains to be elucidated. In this study, we found expression of IFN-ß and IFN stimulated gene CXCL10 in host cells was forcefully elevated after treating with NTHI and NTHI DNA. Interestingly, we tested increased level of STING in NTHI infected mice lung. Meanwhile, STING expression in lung of mimic COPD murine model was higher than healthy mice after NTHI infection. Importantly, knockout of STING or overexpression of STING, TBK1 and IRF3 respectively impaired or enhanced IFN-ß and CXCL10 expression during treating with NTHI and NTHI DNA. NTHI and NTHI DNA-induced I-IFN response appeared to be mediated by cGAS. Collectively, we suggested that NTHI DNA as a PAMP triggered I-IFN response, which was STING/TBK1/IRF3 dependent. SUMMARY: NTHI is the leading cause of acute exacerbations of COPD (AECOPD). Since AECOPD is an immune event, it is meaningful to elucidate the mechanism under NTHI induced immune response. It has been revealed that lipooligosaccharides and protein of NTHI could induce host immune response, but the function of NTHI nuclide acid during infection is unclear. In this research, we demonstrate NTHI DNA is a trigger for I-IFN expression, and the STING/TBK1/IRF3 pathway plays an integral role in sensing NTHI DNA to induce I-IFN expression. Moreover, by long-term intrabronchial infection of LPS, we constructed a mimic COPD murine model, in which the STING expression in lung tissues were higher than healthy mice after NTHI infection, which led us to surmise that NTHI cause AECOPD by inducing I-IFN production via STING signal pathway.

Therapeutic Targeting of Apoptosis Inhibitor of Macrophage/CD5L in Sepsis.

The factors involved in disturbing host homeostasis during sepsis are largely unknown. We sought to determine the immunopathological role of apoptosis inhibitor of macrophage (AIM)/CD5L in sepsis. Here, we show that blockade of AIM led to significantly increased survival after experimental sepsis, and it decreased local and systemic inflammation, reduced tissue injury, and inhibited bacterial dissemination in the blood, in particular at later time points. Supplementation of recombinant AIM in sepsis resulted in increased tissue injury, amplified inflammation, increased bacteremia, and worsened mortality. Interestingly, the most important difference in the production of cytokines and chemokines after in vivo AIM blockade or AIM administration during sepsis was IL-10. In vitro, AIM enhanced IL-10 production from macrophages, neutrophils, or lymphocytes. In vivo, the beneficial effects of AIM blockade and the detrimental effects of AIM addition on experimental sepsis were ablated by treatment with recombinant IL-10 and neutralizing anti-IL-10 antibodies, respectively. This study is the first to identify AIM as an important mediator in disturbing host homeostasis in sepsis.

Interleukin 28 is a potential therapeutic target for sepsis.

Identification of new therapeutic targets for the treatment of sepsis is imperative. We report here that cytokine IL-28 (IFN-λ) levels were elevated in clinical and experimental sepsis. Neutralization of IL-28 protected mice from lethal sepsis induced by cecal ligation and puncture (CLP), which was associated with improved bacterial clearance and enhanced neutrophil infiltration. Conversely, administration of recombinant IL-28 aggravated mortality, facilitated bacterial dissimilation and limited neutrophil recruitment, in the model of sepsis induced by CLP. This study defines IL-28 as a detrimental mediator during sepsis and identifies a potential therapeutic target for the immune therapy in sepsis.

Progranulin aggravates pulmonary immunopathology during influenza virus infection.

Progranulin (PGRN) exerts multiple functions in various inflammatory diseases. However, the role of PGRN in the pathogenesis of virus infection is unknown. Here, we demonstrated that PGRN production was up-regulated in clinical and experimental influenza, which contributed to the deleterious inflammatory response after influenza virus infection in mice. PGRN-deficient mice were protected from influenza virus-induced lung injury and mortality. Decreased mortality was associated with significantly reduced influx of neutrophils and monocytes/macrophages, release of cytokines and chemokines, and permeability of the alveolar-epithelial barrier without affecting viral clearance. Our findings suggest that PGRN exacerbates pulmonary immunopathology during influenza virus infection.

miR-29b Reverses T helper 1 cells/T helper 2 cells Imbalance and Alleviates Airway Eosinophils Recruitment in OVA-Induced Murine Asthma by Targeting Inducible Co-Stimulator.

Asthma is a complex chronic disease and the pathogenesis is still not entirely clear. In this study, we aimed to clarify the role and mechanism of miR-29b in the development of asthma. We observed that miR-29b levels were decreased in the lung and spleen of OVA-induced asthmatic mice. Reverse transcription-quantitative polymerase chain reaction and flow cytometry demonstrated that the inducible co-stimulator (ICOS) expression at mRNA and protein levels was elevated in the lung of asthmatic mice, and miR-29b expression in the lung of asthmatic mice was negatively associated with ICOS mRNA levels by Pearson Correlation analysis. Additional, flow cytometry showed that the percentage of CD4+ICOS+ T cells in the lung and spleen was regulated by miR-29b, and dual luciferase reporter assay confirmed ICOS was a target gene of miR-29b. Furthermore, miR-29b overexpression in asthmatic mice was induced with miR-29b agomir by intranasal administration; miR-29b alleviated total inflammatory cell infiltration and CCL24 levels, decreased IL-5 levels in bronchoalveolar lavage fluid and serum, and upregulated IFN-γ expression in serum. This study demonstrates that miR-29b targets ICOS, thereby reverses the imbalance of T helper 1 cells (Th1)/Th2 responses and decreases eosinophils recruitment in the airway, which are key features of allergic airway inflammation. Therefore, miR-29b might be an attractive candidate target for asthma treatment.

Chromatin remodeling: demethylating H3K4me3 of type I IFNs gene by Rbp2 through interacting with Piasy for transcriptional attenuation.

Type I IFNs (IFNIs) are involved in the course of antiviral and antimicrobial activities; however, robust inductions of these can lead to host immunopathology. We have reported that the Pias (protein inhibitor of activated signal transducer and activator of transcription) family member, Piasy, possesses the ability to suppress IFNI transcriptions in mouse embryonic fibroblasts (MEFs), yet the specific molecular mechanism by which it acts remains elusive. Here, we identify that the H3K4me3 levels, one activation mark of genes, in MEFs that were stimulated by poly(I:C) were impaired by Piasy in the IFN-ß gene. Piasy bound to the promoter region of the IFN-ß gene in MEFs. Meanwhile, retinoblastoma binding protein 2 (Rbp2) was proven to be the only known and novel H3K4me3 demethylase that interacted with Piasy. Overexpression of Rbp2, but not its enzymatically inactive mutant Rbp2H483G/E485Q, retarded the transcription activities of IFNI, whereas small interfering RNA-mediated or short hairpin RNA-mediated knockdown of Rbp2 enhanced IFNI promoter responses. Above all, coexpression of Piasy and Rbp2 led to statistically less IFNI induction than overexpression of either Piasy or Rbp2 alone. Mechanistically, Piasy bound to the Jmjc domain (451-503 aa) of Rbp2 via its PINIT domain (101-218 aa), which is consistent with the domain required for their attenuation of transcription and H3K4me3 levels of IFNI genes. Our study demonstrates that Piasy may prevent exaggerated transcription of IFNI by Rbp2-mediated demethylation of H3K4me3 of IFNI, avoiding excessive immune responses.-Yu, X., Chen, H., Zuo, C., Jin, X., Yin, Y., Wang, H., Jin, M., Ozato, K., Xu, S. Chromatin remodeling: demethylating H3K4me3 of type I IFNs gene by Rbp2 through interacting with Piasy for transcriptional attenuation.