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Aim: Protein vaccines have been the focus of research for vaccine development due to their safety record and facile production. Improving the stability of proteins is of great significance to the application of protein vaccines. Materials & methods: Based on the proteins pneumolysin and DnaJ of Streptococcus pneumoniae, biomineralization was carried out to prepare protein nanoparticles, and their thermal stability was tested both in vivo and in vitro. Results: Mineralized nanoparticles were formed successfully and these calcium phosphate-encapsulated proteins were resistant to proteinase K degradation and were thermally stable at high temperatures. The mineralized proteins retained the immunoreactivity of the original proteins. Conclusion: Mineralization technology is an effective means to stabilize protein vaccines, presenting a safe and economical method for vaccine administration.

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.

Pneumolysin (Ply) is a major virulence factor of Streptococcus pneumoniae. Ply-induced interferon-β (IFN-β) 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-β 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-β in epithelial cells, and this response was mediated by mtDNA released from Ply-damaged mitochondria. It displayed an impressive modulation of IFN-β response to S. pneumoniae in epithelial cells.

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 CD11c

Pneumolysin (Ply), a major virulence factor of Streptococcus pneumoniae (S. pn), affects the immunity of host cells during infection. It has been reported that Ply is involved in S. pn standard strain D39-induced interferon-β (IFN-β) expression; however, other findings suggest that recombinant Ply protein is incapable of triggering IFN-β expression. Here, we demonstrated that purified Ply was capable of initiating oxidative damage to mitochondria, resulting in the subsequent release of mitochondrial deoxyribonucleic acid (mtDNA), which mediated IFN-β expression in macrophages. Importantly, we determined that IFN-β expression was regulated by stimulator of interferon genes (STING) signaling in response to Ply. In conclusion, our study identified that IFN-β production was triggered by Ply in macrophages and mtDNA released from Ply-damaged mitochondria mediated this process, through the STING pathway. This is a novel mechanism by which S. pn modulates type I IFN response in macrophages.

Xu Chen,1,2,* Jing Yang,3,* Hailan Shen,4 Xuemei Zhang,1 Hong Wang,1 Guangying Wu,1 Yuhong Qi,1 Ling Wang,1 Wenchun Xu1 1Key Laboratory of Laboratory Medical Diagnostics Designated by the Ministry of Education, School of Laboratory Medicine, Chongqing Medical University, Chongqing, People’s Republic of China; 2Department of Clinical Laboratory, First People’s Hospital of Liangshan Yi Autonomous Prefecture, Xichang, Sichuan, People’s Republic of China; 3Department of Clinical Laboratory, Chengdu Women’s and Children’s Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, 611731, People’s Republic of China; 4Department of Laboratory Medicine, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People’s Republic of China*These authors contributed equally to this workCorrespondence: Wenchun XuKey Laboratory of Laboratory Medical Diagnostics Designated by the Ministry of Education, School of Laboratory Medicine, Chongqing Medical University, Chongqing, People’s Republic of ChinaTel +86-2368485239Email xuwen@cqmu.edu.cnIntroduction: LncRNAs play important roles in multiple diseases including asthma, while there are a few reports on the role of lncRNA H19 about asthma. This study aimed to investigate the roles and mechanisms of lncRNA H19 in asthma.Methods: We detected lncRNA H19 and Muc5ac mRNA by establishing a murine asthma model and an in vitro inflammation model. Regulatory roles of lncRNA H19 in asthma were explored by lncRNA H19 overexpression or knockdown in vitro. To study its mechanisms, we detect p-NF-κB and p-Akt expression, and treated 16-HBE cells with inhibitors of PI3K. To study regulatory effects of miR-675-3p on Muc5ac, miR-675-3p mimics and inhibitors were respectively transfected into 16-HBE cells.Results: Firstly, we established a murine asthma model and an in vitro inflammation model. We found that lncRNA H19 expression was decreased, while Muc5ac mRNA was increased in lung tissues of murine asthma model and in the in vitro inflammation model. lncRNA H19 overexpression increased Muc5ac mRNA expression and lncRNA H19 knockdown decreased Muc5ac mRNA expression in 16-HBE cells. Moreover, lncRNA H19 overexpression further increased Muc5ac expression in TNFα-induced in vitro inflammation model. lncRNA H19 knockdown decreased p-Akt and p-NF-κB expression. Inhibitors of PI3K abolished Muc5ac induced by lncRNA H19 overexpression. Although miR-675-3p was increased by lncRNA H19 overexpression, it had no regulatory effects on Muc5ac expression.Discussion: These results demonstrated that lncRNA H19 positively regulates Muc5ac expression through PI3K/Akt /NF-κB pathway in the in vitro inflammation model. Therefore, this study indicated that decreased lncRNA H19 in asthma might play a protective role relieving mucus overproduction, and lncRNA H19 might be a potential target for asthma treatment.Keywords: asthma, lncRNA H19, Muc5ac, NF-κB, Akt

The fusion protein DnaJ-ΔA146Ply is protective against pneumococcal infections in mice. However, we found that immunized IL-4

The cytochrome c oxidase subunit III (COX III) gene is a powerful biomarker for the early diagnosis of acute kidney injury. However, current methods for COX III gene detection are usually laborious and time-consuming, with limited sensitivity. Herein, we report a novel self-electrochemiluminescence (ECL) biosensor for highly sensitive detection of the COX III gene based on CRISPR/Cas12a and nanoemitters of luminol-loaded multicomponent metal-metalloid PdCuBP alloy mesoporous nanoclusters. The nanoemitter with excellent self-ECL in neutral media exhibited a high specific surface area for binding luminol and outstanding oxidase-like catalytic activity toward dissolved O

BACKGROUND AND PURPOSE: Epidemiological and experimental studies suggest that microbial exposure in early childhood is linked with reduced risk to suffer asthma. Thus microbial components with immunoregulatory capabilities might serve as a preventive strategy for allergic asthma. Recently, it was identified that Streptococcus pneumoniae aminopeptidase N (PepN) could suppress T cell effector function. We sought to investigate the effect of PepN on murine allergic asthma and elucidate the underlying mechanism. EXPERIMENTAL APPROACH: The effects of intranasal administration of PepN during or before sensitization were examined in ovalbumin (OVA)‐induced murine allergic asthma. The roles of CD11b(+) dendritic cells in PepN treated OVA‐induced allergic asthma were evaluated by flow cytometry, cytokines detection and adoptive transfer. Moreover, the numbers of lung type 2 innate lymphoid cells (ILC2s) were also detected. KEY RESULTS: Administration of PepN during or before sensitization attenuated type‐2 airway inflammation (eosinophilia, mucus hypersecretion, Th2 cytokines production and IgE production) in allergic asthma mice. PepN reduced lung accumulation of CD11b(+) dendritic cells, which was accompanied by diminished dendritic cell‐attracting chemokine CCL20 production as well as CCL17 and CCL22, which are Th2‐cell chemokines predominantly produced by CD11b(+) dendritic cells. Adoptive transfer of BM‐derived CD11b(+) dendritic cells abolished the inhibitory effect of PepN on OVA‐induced type‐2 airway inflammation. The numbers of lung ILC2s were decreased in asthmatic mice receiving PepN. CONCLUSION AND IMPLICATIONS: PepN alleviated type‐2 inflammation in OVA‐induced allergic asthma mice, which was mediated by regulation of lung CD11b(+) dendritic cells. Our study provides a novel strategy for the prevention of allergic asthma.

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.

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-β 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-β 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.

Vaccine design ushered in the era of nanotechnology, as the vaccine is being developed toward particulate formulation. We have previously shown that the attenuated pneumolysin mutant (ΔA146PLY) was a safe and effective pneumococcal vaccine candidate. Here, to further optimize the formulation, we fused calcium phosphate (CaP) binding domains with ΔA146PLY so that the biocompatible CaP can mineralize with the protein automatically, allowing simple production of nanoparticle antigen during preparation. We fabricated four different nanoparticles, and then we compared the characteristics of different CaP-ΔA146PLY nanoparticles and demonstrated the influence of CaP binding domains on the size, shape and surface calcium content of the nanoparticles. It was found that these self-biomineralized CaP-ΔA146PLY nanoparticles varied in their capacity to induce BMDCs and splenocytes production of cytokines. We further demonstrated that, compared to free proteins, nanoparticle antigens induced more efficient humoral and cellular immune responses which was strong enough to protect mice from both pneumonia and sepsis infection. Also, the integration of CaP to protein has no significant impairment on body weight of animals, and subcutaneous injection of ΔA146PLY-peptides@CaP nanoparticles did not lead to permanent formation of nodules in the skin relative to Alum adjuvant formulated antigens. Together, our data sufficiently suggest that soluble ΔA146PLY vaccine candidate could be processed into nanoparticles by self-biomineralization of CaP, the immunogenicity of which could be efficiently improved by the CaP binding domains and biomineralization.

Streptococcus pneumoniae is a leading cause of infectious diseases in children under 5-year-old. Vaccine has been used as an indispensable strategy to prevent S. pneumoniae infection for more than 30 years. Our previous studies confirmed that mucosal immunization with live attenuated strain SPY1 can protect mice against nasopharyngeal colonization of S. pneumoniae and lethal pneumococcal infection, and the protective effects are comparable with those induced by commercially available 23-valent polysaccharide vaccine. However, live attenuated vaccine SPY1 needs four inoculations to get satisfactory protective effect, which may increase the risk of virulence recovery. It is reported that heterologous primeboost approach is more effective than homologous primeboost approach. In the present study, to decrease the doses of live SPY1 and improve the safety of SPY1 vaccine, we immunized mice with SPY1 and DnaJ protein alternately. Our results showed that heterologous prime-boost immunization with SPY1 and DnaJ protein could significantly reduce the colonization of S. pneumoniae in the respiratory tract of mice, and induce stronger Th1 and Th17 cellular immune responses than SPY1 alone. These results indicate heterologous prime-boost immunization method not only elicits better protective effect than SPY1 alone, but also reduces the doses of live SPY1 and decreases the risk of SPY1 vaccine. This work is the first time to study the protective efficiency with two different forms of S. pneumoniae candidate vaccine, and provides a new strategy for the development of S. pneumoniae vaccine.

Herein, a novel enzyme-free electrochemical immunosensor based on quaternary metallic/nonmetallic PdPtBP alloy mesoporous nanoparticles (MNPs)/MXenes and CuCl2 nanowires (NWs) is reported for detection of kidney injury molecule-1 (KIM-1). PdPtBP MNPs/MXene nanocomposites, the novel signal amplification labels, were successfully synthesized using MXenes with the large surface area and the quaternary PdPtBP MNPs nanozymes with outstanding peroxidase-like catalytic activity. Meanwhile, the combination of high conductive CuCl2 NWs with superior biocompatible gold nanoparticles (AuNPs) is introduced as the substrate to modify the glassy carbon electrode (GCE). Benefiting from the excellent electrochemical performances of PdPtBP MNPs/MXene and CuCl2 NWs, the sandwich-type electrochemical immunosensor showed outstanding analytical performance in the presence of hydrogen peroxide (H2O2). Under the optimized conditions, the electrochemical immunosensor exhibited a good linear response from 0.5 ng/mL to 100 ng/mL with a detection limit of 86 pg/mL. Additionally, the established immunosensing method was successfully applied for the specific detection of KIM-1 in the urine. Thus, the enzyme-free electrochemical immunosensor provides a promising prospect for the detection of KIM-1 in the field of clinical diagnostics.

The surface localized Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) of Streptococcus pneumoniae is best known as housekeeping protein. Currently, GAPDH has been recognized as moonlighting protein and virulent factor. Therefore, we investigate whether GAPDH can act as a suitable vaccine candidate protein to prevent pneumococcal infection. In this study, mice received subcutaneous vaccination with recombinant GAPDH followed by challenge with D39 and 19F showing higher survival rate and lower bacterial loads in nasal washes and lung homogenates than control. Meanwhile, high titers of rGAPDH specific antibody and elevated titers of IgG subtype indicated that rGAPDH could elicit immune response in mice. Then, we investigated the mechanism that immunization with rGAPDH conferred protection against Streptococcus pneumoniae in host. In vitro experiments, rGAPDH induced phenotypic and functional maturation of BMDCs, because the high expression of CD40, CD86 and MHC II and the production of IL-12p70, IL-6 and TNF-α were observed after treatment with rGAPDH. However, the costimulatory molecules and cytokines declined significantly in TLR2-/- and TLR4-/- mice, indicating rGAPDH can be a potential ligand for both TLR2 and TLR4. Subsequent investigations suggested that rGAPDH could also activate the phosphorylation of MAPKs, PI3K-Akt and NF-κB. Meantime, upregulation of mir-146a and downregulation of mir-27a in BMDCs were observed. Taken together, our findings confirm that rGAPDH, a housekeeping protein, is also qualified as a vaccine candidate protein and rGAPDH activates BMDCs in a TLR2 and TLR4 dependent manner.

As a heat shock protein, DnaJ plays an important role in the pathogenesis of pneumococcal infection. However, how the virulence factor-DnaJ elicits host natural immunity still remains unclear. In this study, we investigated the effects of dnaJ deficiency in Streptococcus pneumoniae (S. pneumoniae) on bacterial virulence, and further explored the related molecular mechanisms in vivo and in vitro. By generating dnaJ deficient mutant (ΔdnaJ), the virulence and colonization were detected in murine pneumonia and sepsis models in vivo. Compared with wild-type parent strain, the abilities of rapid colonization and induction of inflammatory responses of ΔdnaJ in mouse lungs were significantly impaired. Simultaneously, recombinant DnaJ purified from E. coli expression system (rDnaJ) induced macrophage strain RAW264.7 to secrete IL-6 by activation of PI3K and JNK signal pathways, which were confirmed by the specific signaling inhibitors. In conclusion, DnaJ, a novel virulence protein, was essential for the virulence and colonization of S. pneumoniae and induced pro-inflammatory cytokine production in macrophages through PI3K/JNK.

Pneumococcal DnaJ was recently shown to be a potential protein vaccine antigen that induces strong Th1 and Th17 immune response against streptococcus pneumoniae infection in mice. However, how DnaJ mediates T cell immune response against S. pneumoniae infection has not been addressed. Here, we investigate whether DnaJ contributes to the development of T cell immunity through the activation of bone marrow-derived dendritic cells (BMDCs). We found that endotoxin-free recombinant DnaJ (rDnaJ) induced activation and maturation of BMDCs via recognition of Toll-like receptor 4 (TLR4) and activation of MAPKs, NF-κB and PI3K-Akt pathways. rDnaJ-treated BMDCs effectively stimulated naive CD4+ T cells to secrete IFN-γ and IL-17A. Splenocytes from mice that were adoptively transferred with rDnaJ-pulsed BMDCs secreted higher levels of IFN-γ and IL-17A compared with those that received PBS-activated BMDCs. Splenocytes from TLR4-/- mice immunized with rDnaJ produced lower levels of IFN-γ and IL-17A compared with those from wild type mice. Our findings indicate that DnaJ can induce Th1 and Th17 immune responses against S. pneumoniae through activation of BMDCs in a TLR4-dependent manner.

Tuberculosis (TB) remains a significant challenge to public health, especially in developing countries. Failure in early diagnosis and lack of rapid and accurate diagnostic methods lead to ongoing prevalence and transmission of TB. Recently, the recombinase polymerase amplification (RPA) technique has made it possible to rapidly amplify and detect nucleic acids without specialized devices. We developed a RPA-based method for identifying Mycobacterium tuberculosis (MTB) by detecting mts90, a more specific target identified in our previous research. Different screening methods were employed for selecting a preferred primer pair of amplification, and probes were confirmed as very fast and reliable tools in the screening of potential primer candidates. The results showed that the mts90 RPA assay was very sensitive and capable of detecting 6 copies of recombinant plasmid containing mts90 sequence per reaction. The assay was specific for detecting MTB, as it did not identify the genomic DNA from other mycobacteria and pathogens. When applied to analyze clinical samples, including sputum, bronchoalveolar lavage fluid (BALF) and tissues, the mts90 RPA assay had a coincidence rate of 96.43% (27/28) compared to the Biochip test, which has been used in clinics for diagnosing TB. The mts90 RPA assay can be completed within 20 minutes at 39 °C without thermal cycling; its simple operation and rapid detection suggest RPA-based MTB assays could be further developed for TB diagnosis in resource-poor settings.

The natural course of otitis media (OM) in most children is acute and self-limiting; however, approximately 10–20% of children can experience persistent or recurrent OM. Determining the host factors that influence outcome of OM will help us design better therapies. This study focused on the role of Toll-like receptor 2 (TLR2) in a pneumococcal OM mouse model. The middle ears (MEs) of wild-type (WT) and TLR2-/- mice were inoculated with Streptococcus pneumoniae (Spn) serotype 19F via transbullar injection. ME TLR2 expression in WT mice was determined by qRT-PCR and immunofluorescence. ME pathological manifestations, inflammatory response, and pneumococcal clearance between WT and TLR2-/- mice were compared after Spn inoculation. TLR2 expression in ME mucosa was markedly enhanced following infection with Spn in WT mice. In contrast to WT mice, TLR2-/- mice exhibited unaffected early ME inflammatory response. During late stage of ME infection, however, the absence of TLR2 can lead to reduced macrophage recruitment, impaired Spn clearance, and prolonged ME inflammation. Our results demonstrate that TLR2 signaling is critical for bacterial clearance and timely resolution of inflammation in OM induced by Spn.

Type I interferon (IFN) is indispensable for antiviral immunity, but its role in bacterial infections is controversial and not fully described. Nontypeable Haemophilus influenzae (NTHi) is one of the most common bacterial pathogens in patients with chronic obstructive pulmonary disease (COPD). NTHi-DNA activates type I IFN production in macrophages, but the function of type I IFN in host-pathogen interactions, in the context of NTHi infection, is still unclear. Here, we showed that type I IFN, induced by NTHi-DNA, restrained bacterial killing in vitro and promoted COPD development in vivo in response to NTHi. Mice deficient for type I IFN receptor (IFNAR) exhibited improved resistance to NTHi infection. Moreover, similar to exogenous IFN-β, NTHi-DNA-induced type I IFN increased the production of IL-6, IL-1β, IL-12 and CXCL10 via p38 MAPK activation. Our findings demonstrated that NTHi-DNA-induced type I IFN signaling played a negative role in host defense against NTHi infection and identified potential targets for future therapeutic management of COPD.

Background: Mast cells participate in immune responses by releasing potent immune system modifiers via degranulation. Due to currently reported controversial roles of mast cells in Streptococcus pneumoniae infections, this study aimed to determine the role and mechanism of mast cells in clearing S. pneumoniae in mice. Methods: In vivo mouse model of mast cell degranulation established by administration of C48/80 was evaluated for the influences of mast cell degranulation on bacterial colonization and inflammation. In vitro model was established to observe the influences of mast cell degranulation on phagocytic and bactericidal functions of neutrophils and macrophages. IL-6 null and TNF-α null mice on the C57BL/6 background were used to investigate the effects of inflammatory factors released by mast cell degranulation on bacterial clearance. Results: Mast cell degranulation increased IL-6 and TNF-α levels and immune cell numbers in nasal lavage fluid, and inhibited the bactericidal function of macrophages and neutrophils in vitro. It decreased the number of neutrophils and macrophages recruited to respiratory tract after S. pneumoniae challenge and inhibited the clearance of S. pneumoniae in mice. After pretreatment with C48/80, S. pneumoniae loads were significantly lower in IL-6 null mice than in wild type mice, while no differences were observed between TNF-α null and wild type mice. Conclusions: Mast cell degranulation can cause inflammation and impair immune cell recruitment to respiratory tract after S. pneumoniae challenge. Products of mast cell degranulation including IL-6 decreased the bactericidal function of neutrophils and macrophages. Through these mechanisms, mast cell degranulation inhibited clearance of S. pneumoniae in mice. Keywords: Degranulation, Inflammatory response, Mast cell, Streptococcus pneumoniae

Objectives: To investigate the molecular epidemiology of pneumococcal isolates in Chongqing, China. Methods: In this cross-sectional study, 51 invasive Streptococcus pneumoniae ( S. pneumoniae ) strains were from children with invasive pneumococcal disease (IPD) and 32 carriage strains from healthy children from January 2010 to December 2013 at the Children’s Hospital of Chongqing Medical University, Chongqing, China. Multilocus sequence typing was used to identify the sequence types (STs). Capsular serotypes were determined by multiplex polymerase chain reaction. Drug susceptibility and resistance was determined by minimum inhibitory concentrations. Results: In this study, 11 serotypes were identified among the 83 S. pneumoniae clinical isolates tested. Prevalent serotypes were 19A (20.4%), 6A/B (20.4%), 19F (15.7%), 14 (14.5%), and 23F (10.8%). Serotype 19F was the most frequent carriage strain, and serotype 19A was the most frequent invasive strain. The ST983 was the most prevalent ST for carriage strains, and ST320 was the most prevalent ST for invasive strains. For gene analysis, psaA (99.5%) and piaA (98.6%) were present and much conserved in all pneumococci tested. The cps2A and pcsB genes were more frequent in invasive isolates than carriage strains. Antimicrobial resistance rates of invasive pneumococcal isolates to erythromycin, penicillin, meropenem, cefotaxime, and clindamycin were higher than the carriage isolates from children. Conclusion: Our epidemiological evidence shows that 19A, 6A/B, 19F, 14, and 23F remain the most prevalent serotypes, which can be targeted by PCV13. Genotypes and drug resistance varied between carriage and invasive strains. The PsaA and PiaA may be good protein vaccine candidates. Saudi Med J 2016; Vol. 37 (4): 403-413 doi: 10.15537/smj.2016.4.14507 How to cite this article: Kang LH, Liu MJ, Xu WC, Cui JJ, Zhang XM, Wu KF, et al. Molecular epidemiology of pneumococcal isolates from children in China. Saudi Med J 2016; 37: 403-413.

spd1672, a novel Streptococcus pneumoniae (hereinafter S. pn) gene induced in vivo, has been identified to contribute to the virulence of S. pn; however, the role of spd1672 during host innate immune reaction against S. pn infection is unknown. In the present study, mice were infected with wild-type D39 and mutant D39Δspd1672 strains. Compared with the D39-infected mice, reduced bacterial load and attenuated inflammatory response were observed in the D39Δspd1672-treated mice. The levels of proinflammatory cytokines, including IFN-γ, TNF-α, and IL-1β, in the blood of D39Δspd1672-infected mice were lower than that in the D39-infected group. Additionally, attenuated activation of STAT3 and AKT was observed in the D39Δspd1672-infected mice. In conclusion, our data indicated that spd1672 expression modulates the release of proinflammatory cytokines, and AKT–STAT3 signaling appears to participate in the process. In conclusion, the present study extends our understanding of the role of an in vivo-induced gene in S. pn–host interaction.

Streptococcus pneumoniae is a major pathogen leading to substantial morbidity and mortality in children under 5 years of age. Vaccination is an effective strategy to prevent S. pneumoniae infection. SPY1 is a pneumococcal vaccine candicate strain obtained in our previous study. To improve its stability and immunogencity, in this study, we constructed the SPY1△lytA strain which lacks autolysin activity and was coated with an artificial exterior surface calcium phosphate shell by in situ mineralization. The resulting strain SPY1△lytACaPi displayed enhanced thermal stability enabling storage at 37oC for one week. Furthermore, mucosal and subcutaneous immunization with the SPY1△lytACaPi strain induced better protective effects than SPY1△lytA in anti-colonization after challenging with 19F and anti-invasion by D39 in mice. Subcutaneous immunization with SPY1△lytACaPi elicited higher IgG level while mucosal immunization primarily elicited an immune response which is supposed to be related to Th17 cells. Taken together, the mineralized strain may be a promising candidate for an attenuated S. pneumoniae vaccine.

Streptococcus pneumoniae, a major respiratory pathogen, is a leading cause of death among children worldwide. Mucosal vaccination is a recommended method to prevent respiratory infection. However, development of mucosal vaccination is usually hindered due to the lack of safe and effective mucosal adjuvants. Mast cell activator compound 48/80 (C48/80) has been used as a mucosal adjuvant in immunization of adult mice, but its adjuvanticity is not clear in the immunization of young mice. In this study, the adjuvanticity of C48/80 was evaluated when intranasally co-administrated with a pneumococcal vaccine candidate strain SPY1 in a young mice model in comparison with a classical mucosal adjuvant cholera toxin (CT) and a relatively safe mucosal adjuvant Pam2CSK4. All three adjuvants enhanced antibody responses, whereas serum IgG titers were maintained at a stable level during the 3 months after the last immunization only in the SPY1+C48/80 and SPY1+CT groups. Furthermore, both the SPY1+CT group and the SPY1+C48/80 group induced strong Th17 immune response. Notably, C48/80 showed the exceptional ability to promote the clearance of nasal pneumococcal colonization which CT and Pam2CSK4 did not show. We found that C48/80's ability to induce protection against nasal pneumococcal colonization depended on B cells and IL-17A. Additionally, C48/80, as a mucosal adjuvant, showed a greater ability to protect young mice against lethal pneumococcal infection than CT. In comparison with CT, C48/80 also showed a favorable safety. These results reveal a promising perspective for using C48/80 as a mucosal adjuvant to improve protection against pneumococcal diseases early in life.

Summary Airway inflammatory diseases such as chronic obstructive pulmonary disease (COPD) and asthma are associated with elevated expression of interleukin-32 (IL-32), a recently described cytokine that appears to play a critical role in inflammation. However, so far, the regulation of pulmonary IL-32 production has not been fully established. We examined the expression of IL-32 by tumour necrosis factor-α (TNF-α) in primary human lung fibroblasts. Human lung fibroblasts were cultured in the presence or absence of TNF-α and/or other cytokines/Toll-like receptor (TLR) ligands or various signalling molecule inhibitors to analyse the expression of IL-32 by quantitative RT-PCR and ELISA. Next, activation of Akt and c-Jun N-terminal kinase (JNK) signalling pathways was investigated by Western blot. Interleukin-32 mRNA of four spliced isoforms (α, β, γ and δ) was up-regulated upon TNF-α stimulation, which was associated with a significant IL-32 protein release from TNF-α-activated human lung fibroblasts. The combination of interferon-γ and TNF-α induced enhanced IL-32 release in human lung fibroblasts, whereas IL-4, IL-17A, IL-27 and TLR ligands did not alter IL-32 release in human lung fibroblasts either alone, or in combination with TNF-α. Furthermore, the activation of Akt and JNK pathways regulated TNF-α-induced IL-32 expression in human lung fibroblasts, and inhibition of the Akt and JNK pathways was able to suppress the increased release of IL-32 to nearly the basal level. These data suggest that TNF-α may be involved in airway inflammation via the induction of IL-32 by activating Akt and JNK signalling pathways. Therefore, the TNF-α/IL-32 axis may be a potential therapeutic target for airway inflammatory diseases.

Mucosal immunization with attenuated vaccine can protect against pneumococcal invasion infection, but the mechanism was unknown. Our study found that mucosal delivery with the live attenuated SPY1 vaccine strain can confer T cell- and B cell-dependent protection against pneumococcal colonization and invasive infection; yet it is still unclear which cell subsets contribute to the protection, and their roles in pneumococcal colonization and invasion remain elusive. Adoptive transfer of anti-SPY1 antibody conferred protection to naive μMT mice, and immune T cells were indispensable to protection examined in nude mice. A critical role of interleukin 17A (IL-17A) in colonization was demonstrated in mice lacking IL-17A, and a vaccine-specific Th2 immune subset was necessary for systemic protection. Of note, we found that SPY1 could stimulate an immunoregulatory response and that SPY1-elicited regulatory T cells participated in protection against colonization and lethal infection. The data presented here aid our understanding of how live attenuated strains are able to function as effective vaccines and may contribute to a more comprehensive evaluation of live vaccines and other mucosal vaccines.

Acute otitis media (AOM) is one of the most common bacterial infectious diseases in children aged 2 to 7 years worldwide. We previously demonstrated that interleukin-17A (IL-17A) promotes an acute inflammatory response characterized by the influx of neutrophils into the middle ear cavity during Streptococcus pneumoniae -induced AOM. In general, the inflammatory response is viewed as an effector that frequently causes local tissue damage. However, little is known about the pathogenic effects of IL-17A in AOM. Here, we investigated the pathogenic effects of IL-17A by using wild-type (WT) and IL-17A knockout (KO) mouse models. The results showed that the pathogenic effects of AOM, including weight loss, histopathological changes, and proinflammatory cytokine production, were more severe in WT mice than in IL-17A KO mice, suggesting that IL-17A aggravates tissue damage in AOM. Furthermore, these pathogenic effects were found to be dependent on p38 mitogen-activated protein kinase (MAPK) and could be reversed in the presence of a p38 MAPK-specific inhibitor. It was also demonstrated that IL-17A promoted the production of neutrophil myeloperoxidase (MPO) through the p38 MAPK signaling pathway, which was responsible for the middle ear tissue injury. These data support the conclusion that IL-17A contributes to middle ear injury through the p38 MAPK signaling pathway.

Background Interleukin 4 (IL-4) is an important cytokine that may modulate development of secondary bacterial pneumonia during sepsis-induced immunosuppression. Methods We established an experimental model of cecal ligation and puncture (CLP)-induced sublethal polymicrobial sepsis followed by secondary Pseudomonas aeruginosa pulmonary infection, Results IL-4-deficient mice that underwent CLP were resistant to secondary pulmonary P. aeruginosa infection. As compared to wild-type mice, IL-4 knockout (KO) mice displayed improved survival and better bacterial clearance. Furthermore, IL-4 KO mice exhibited enhanced lung inflammation, neutrophil recruitment to airspaces, and elevated pulmonary cytokine production, with significantly increased tumor necrosis factor α (TNF-α) production. Neutralization of TNF-α could reverse the enhanced protection against secondary P. aeruginosa pneumonia in septic IL-4 KO mice, indicating that the resistance of septic IL-4 KO mice to secondary bacterial pneumonia was partially mediated by TNF-α. In addition, IL-4 priming displayed marked impairment of the ability of alveolar macrophages to phagocytose and kill P. aeruginosa in vitro, and this defect was associated with decreased activation of Akt, JNK, p38MAPK, and ERK intracellular signaling pathways by IL-4. Finally, neutralization of IL-4 in septic mice could improve survival and clearance of bacteria from the lungs of septic mice infected with P. aeruginosa. Conclusions Our findings provide new insight for immunopathologic mechanisms of sepsis-induced secondary bacterial pneumonia.

IL-27 is involved in inflammatory reactions. CXCL10 is an important chemokine contributing to airway inflammatory disease. In this study, we investigated whether IL-27 modulated the synthesis of CXCL10 in primary human lung fibroblasts (HLFs). HLFs were activated by IL-27 alone, or in combination with other cytokines. CXCL10 synthesis was measured by real-time PCR and ELISA. An examination of transcriptional regulation was performed via the transient transfection of promoter constructs, whereas mRNA stability was assessed by actinomycin D chase and real-time PCR. The underlying signaling pathways were studied by Western blotting and intracellular staining, using flow cytometry. Our results demonstrated that IL-27 induced and synergized with TNF-α to up-regulate CXCL10 mRNA and protein concentrations in a steroid-insensitive manner. This synergistic CXCL10 production was dependent on the transcriptional regulation of CXCL10 gene promoter activity and the enhanced stability of CXCL10 mRNA because of IL-27 a...

To obtain recombinant cystatin C (CysC) protein, which can be used in immunological diagnostic kits, we focused on the preparation of tag-free CysC. The 6 × His-TF-CysC fusion protein was found to overexpress in soluble form in cells of BL21-Gold (DE3)/pCold TF-CysC, which had been induced with isopropyl-D-1-thiogalactopyranoside. Subsequently, we established a protein purification method for tag-free CysC using immobilized metal-affinity chromatography and size-exclusion chromatography. In this method, glutathione-S-transferase-human rhinovirus 3C proteases were used to remove the protein tags. High homogeneity of the purified CysC was determined by SDS-PAGE, while the purity of the tag-free CysC was ascertained to be above 95%. With a yield of 25 mg/L from bacterial culture, the biological activity of the tag-free CysC was evaluated as inhibitors like natural CysC. The performance of this purification method was successfully evaluated in the preparation of other low molecular weight heterologous proteins in Escherichia coli.

Increasing pressure in antibiotic resistance and the requirement for the design of new vaccines are the objectives of clarifying the putative virulence factors in pneumococcal infection. In this study, the putative threonine dehydratase sp0454 was inactivated by erythromycin-resistance cassette replacement in Streptococcus pneumoniae CMCC 31203 strain. The sp0454 mutant was tested for cell growth, adherence, colonization, and virulence in a murine model. The Δsp0454 mutant showed decreased ability for colonization and impaired ability to adhere to A549 cells. However, the SP0454 polypeptide or its antiserum did not affect pneumococcal CMCC 31203 adhesion to A549 cells. The sp0454 deletion mutant was less virulent in a murine intranasal infection model. Real-time RT-PCR analysis revealed significant decrease of the pneumococcal surface antigen A expression in the sp0454 mutant. These results suggest that SP0454 contributes to virulence and colonization, which could be explained in part by modulating the expression of other virulence factors, such as psaA in pneumococcal infection.

Previous reports suggest that ClpP proteolytic activity is important not only for cell physiology but also for regulation of virulence properties of Streptococcus pneumoniae (S. pneumoniae). In order to get a more comprehensive picture of the role of ClpP protease on protein expression in S. pneumoniae D39 and how it relates to physiology and virulence, a clpP mutant strain was constructed in S. pneumoniae D39, and global proteome expression was studied by 2-dimensional electrophoresis and matrix-assisted laser desorption-ionization-time of flight mass spectrometry. We report here that clpP deletion affects the expression of proteins which are involved in the general stress response, nucleotide metabolism, energy metabolism, and proteins metabolism. These provide clues for understanding the role of ClpP in the physiology and pathogenesis of pneumococcus.

Interaction between virulence factors of streptococcus pneumoniae and innate immune receptors elicits host responses through specific signaling pathways during infection. Insights into the signaling events may provide a better knowledge of the starting events for host-pathogen interaction. Here we demonstrated a significant induction of innate immune response elicited by recombinant streptococcus pneumoniae endopeptidase O (rPepO), a newer pneumococcal virulence protein, both in vivo and in vitro. Intratracheal instillation of rPepO protein resulted in significant increase of cytokines production and neutrophils infiltration in mouse lungs. TLR2 or TLR4 deficient mice subjected to rPepO treatment showed decreased cytokines production, reduced neutrophils infiltration and intensified tissue injury as compared with WT mice. Upon stimulation, cytokines TNF-α, IL-6, CXCL1 and CXCL10 were produced by peritoneal exudate macrophages (PEMs) in a TLR2 and TLR4 dependent manner. rPepO- induced cytokines production was markedly decreased in TLR2 or TLR4 deficient PEMs. Further study revealed that cytokines induction relied on the rapid phosphorylation of p38, Akt and p65, not the activation of ERK or JNK. While in TLR2 or TLR4 deficient PEMs the activation of p65 was undetectable. Taken together, these results indicate for the first time that the newer pneumococcal virulence protein PepO activates host innate immune response partially through TLR2 and TLR4 signaling pathways.