Single-cell transcriptome reveals highly complement activated microglia cells in association with pediatric tuberculous meningitis.

Background: Tuberculous meningitis (TBM) is a devastating form of tuberculosis (TB) causing high mortality and disability. TBM arises due to immune dysregulation, but the underlying immune mechanisms are unclear. Methods: We performed single-cell RNA sequencing on peripheral blood mononuclear cells (PBMCs) and cerebrospinal fluid (CSF) cells isolated from children (n=6) with TBM using 10 xGenomics platform. We used unsupervised clustering of cells and cluster visualization based on the gene expression profiles, and validated the protein and cytokines by ELISA analysis. Results: We revealed for the first time 33 monocyte populations across the CSF cells and PBMCs of children with TBM. Within these populations, we saw that CD4_C04 cells with Th17 and Th1 phenotypes and Macro_C01 cells with a microglia phenotype, were enriched in the CSF. Lineage tracking analysis of monocyte populations revealed myeloid cell populations, as well as subsets of CD4 and CD8 T-cell populations with distinct effector functions. Importantly, we discovered that complement-activated microglial Macro_C01 cells are associated with a neuroinflammatory response that leads to persistent meningitis. Consistently, we saw an increase in complement protein (C1Q), inflammatory markers (CRP) and inflammatory factor (TNF-α and IL-6) in CSF cells but not blood. Finally, we inferred that Macro_C01 cells recruit CD4_C04 cells through CXCL16/CXCR6. Discussion: We proposed that the microglial Macro_C01 subset activates complement and interacts with the CD4_C04 cell subset to amplify inflammatory signals, which could potentially contribute to augment inflammatory signals, resulting in hyperinflammation and an immune response elicited by Mtb-infected tissues.

Epidemiological Characteristics of Human Parainfluenza Viruses Infections - China, 2019-2023.

Introduction: A retrospective study based on sentinel surveillance was conducted in 10 provincial-level administrative divisions (PLADs) in China to enhance the understanding of the epidemiological characteristics of human parainfluenza viruses (HPIVs). Methods: From January 2019 to June 2023, respiratory specimens were collected from individuals with acute respiratory infections (ARIs) and screened for four HPIVs serotypes and other common respiratory viruses using multiplex real-time polymerase chain reaction (PCR). This study analyzed the association of HPIVs infections with seasonal patterns, geographical distribution, demographic profiles, clinical features, and co-infection status. Results: During the study period, a total of 12,866 ARIs were included. The overall detection rate of HPIVs was 6.15%, varying from 5.04% in 2022 to 9.70% in 2020. The median age of HPIVs-infected patients was 3 years. HPIV2 was more prevalent among individuals aged 5-17 years (42.57%), while HPIV4 was more common in those over 65 years (12.24%). HPIV3 (54.16%) and HPIV1 (27.18%) were the predominant serotypes, and their prevalence exhibited significant seasonal fluctuations post- coronavirus disease 2019 (COVID-19) pandemic. The peak of HPIV3 shifted three months later in 2020 compared to 2019 and returned to a summer peak thereafter. Two peaks of HPIV1 were observed in 2021 following the peak of HPIV3. Additionally, co-infections were frequent in HPIVs cases (overall rate: 22.12%), with human rhinovirus being the most common co-infecting virus. Conclusions: The prevalence of HPIVs in China was predominantly due to HPIV3 and HPIV1, and their seasonal patterns were altered by pandemic restrictions. Hence, continuous surveillance of HPIVs is essential.

IL-17A plays a critical role in RSV infection in children and mice.

BACKGROUND: IL-17A is a pleiotropic cytokine and intimately associated with asthma, but its role in respiratory syncytial virus (RSV) infection is conflicting in the literature. METHODS: Children hospitalized in the respiratory department with RSV infection during RSV pandemic season of 2018-2020 were included. Nasopharyngeal aspirates were collected for pathogen and cytokines determination. In the murine model, RSV intranasal administrations were performed in wild-type and IL-17A-/- mice. Leukocytes and cytokines in bronchoalveolar lavage fluid (BALF), lung histopathology, and airway hyperresponsiveness (AHR) were measured. RORγt mRNA and IL-23R mRNA were semi-quantified by qPCR. RESULTS: IL-17A increased significantly in RSV-infected children and was positively associated with pneumonia severity. In the murine model, IL-17A significantly increased in BALF of mice with RSV infection. Airway inflammation, lung tissue damage and AHR were significantly alleviated in wild-type mice following IL-17A neutralization and in the IL-17A-/- mice. IL-17A decreased by removing CD4+ T cells but increased by depleting CD8+ T cells. IL-6, IL-21, RORγt mRNA and IL-23R mRNA dramatically increased in parallel with the rise of IL-17A. CONCLUSIONS: IL-17A contributes to the airway dysfunctions induced by RSV in children and murine. CD3+CD4+T cells are its major cellular sources and the IL-6/IL-21-IL-23R-RORγt signaling pathway might participate in its regulation.

Effectiveness of ertapenem for treatment of infections in children: An evidence mapping and meta-analysis.

Objectives: To assess and summarize current evidence on the effectiveness and safety of ertapenem for treatment of childhood infections, in consideration of high infection prevalence in children and wide use of ertapenem. Methods: The following 8 databases were searched on 13th May 2021: Web of Science, Embase via Ovid SP, PubMed, The Cochrane Library (CENTRAL), Chinese BioMedical Literature Database (CBM), China National Knowledge Infrastructure (CNKI), VIP and Wanfang. The primary outcome was treatment success rate. Risk ratios (RRs) and 95% confidence interval (CI) were estimated using random-effect models. Subgroup analysis was conducted where heterogeneity was found. Results: Fifteen studies (8 randomized controlled trials, 1 observational comparative study, and 6 before and after studies) involving 2,528 patients were included in the final review. Ertapenem had similar treatment success rates with ß-lactam antibiotics [relative risk (RR) = 1.08, 95% CI: 0.99-1.19]. In a subgroup analysis, similar efficacy (RR = 1.08, 95% CI: 0.97-1.20) between ertapenem and other carbapenems. Compared with ß-lactam antibiotics, ertapenem did not increase the risk of any adverse events (RR = 1.02, 95%CI: 0.71-1.48), drug-related diarrhea (all non-Asian children, RR = 0.62, 95%CI: 0.31-1.25), or injection site pain (all non-Asian children, RR = 1.66, 95%CI: 0.59-4.68). Subgroup analysis showed no obvious difference between ertapenem group and carbapenems or non-carbapenems group on risk of adverse events. Conclusion: Our findings suggest that ertapenem is effective and safe in treatment for children with infection. Further comparative real-world data is needed to supplement clinical evidence on the overall benefits of ertapenem in this population.

Mycobacterium tuberculosis Utilizes Host Histamine Receptor H1 to Modulate Reactive Oxygen Species Production and Phagosome Maturation via the p38MAPK-NOX2 Axis.

Tuberculosis (TB), which is caused by the single pathogenic bacterium, Mycobacterium tuberculosis, is among the top 10 lethal diseases worldwide. This situation has been exacerbated by the increasing number of cases of multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB). Histamine is an organic nitrogenous compound that mediates a plethora of cell processes via different receptors. The expression of histamine receptor H1 (HRH1), one of the four histamine receptors identified to date was previously reported to be augmented by M. tuberculosis infection, although the underlying mechanism is unclear. In the present study, we applied confocal microscopy, flow cytometry, and Western blotting to show that HRH1 expression was enhanced in macrophages following mycobacterial infection. Furthermore, by combining techniques of gene knockdown, immunoprecipitation, intracellular bacterial burden analysis, fluorescence labeling, and imaging, we found that M. tuberculosis targeted the host HRH1 to suppress NOX2-mediated cROS production and inhibit phagosome maturation and acidification via the GRK2-p38MAPK signaling pathway. Our findings clarified the underlying mechanism of the M. tuberculosis and host HRH1 interaction and may provide useful information for the development of novel antituberculosis treatments. IMPORTANCE Once engulfed in macrophage phagosomes, M. tuberculosis adopts various strategies to take advantage of the host environment for its intracellular survival. Histamine is an organic nitrogen-containing compound that mediates a plethora of cellular processes via different receptors, but the crosstalk mechanism between M. tuberculosis and HRH1 in macrophages is not clear. Our results revealed that M. tuberculosis infection enhanced HRH1 expression, which in turn restrained macrophage bactericidal activity by modulating the GRK2-p38MAPK signaling pathway, inhibiting NOX2-mediated cROS production and phagosome maturation. Clarification of the underlying mechanism by which M. tuberculosis utilizes host HRH1 to favor its intracellular survival may provide useful information for the development of novel antituberculosis treatments.

Corrigendum: Effectiveness of ertapenem for treatment of infections in children: An evidence mapping and meta-analysis.

[This corrects the article DOI: 10.3389/fpsyt.2021.706625.].

Analysis of Factors Influencing Multidrug-Resistant Tuberculosis and Validation of Whole-Genome Sequencing in Children with Drug-Resistant Tuberculosis.

OBJECTIVE: Pediatric tuberculosis (TB) is one of the top ten causes of death in children. Our study was to analyze influencing factors of multidrug-resistant tuberculosis (MDR-TB) and validation of whole-genome sequencing (WGS) used in children with drug-resistant TB (DR-TB). METHODS: All Mycobacterium tuberculosis (Mtb) strains were isolated from patients aged below 18 years old of Children's Hospital of Chongqing Medical University, China. A total of 208 Mtb isolates were tested for eight anti-TB drugs with phenotypic drug susceptibility test (DST) and for genetic prediction of the susceptible profile with WGS. The patients corresponding to each strain were grouped according to drug resistance and genotype. Influencing factors of MDR-TB and DR-TB were analyzed. RESULTS: According to the phenotypic DST and WGS, 82.2% of Mtb strains were susceptible to all eight drugs, and 6.3% were MDR-TB. Using the phenotypic DSTs as the gold standard, the kappa value of WGS to predict isoniazid, rifampin, ethambutol, rifapentine, prothionamide, levofloxacin, moxifloxacin and amikacin was 0.84, 0.89, 0.59, 0.86, 0.89, 0.82, 0.88 and 1.00, respectively. There was significant difference in the distribution of severe TB, diagnosis, treatment and outcome between MDR and drug-susceptible group (P<0.05). The distribution of severe TB and treatment between DR and drug-susceptible group was statistically different (P<0.05). The results of binary logistic regression showed that Calmette-Guérin bacillus (BCG) vaccine is the protective factor for MDR-TB (OR=0.19), and MDR-TB is the risk factor for PTB and EPTB (OR=17.98). CONCLUSION: The BCG vaccine is a protective factor for MDR-TB, and MDR-TB might not be confined to pulmonary infection, spreading to extrapulmonary organs in children. MDR-TB had more severe cases and a lower recovery rate than drug-susceptible TB. WGS could provide an accurate prediction of drug susceptibility test results for anti-TB drugs, which are needed for the diagnosis and precise treatment of TB in children.

Follow-up Study of Long-time Positive RT-PCR in Stool Specimens From Asymptomatic Children Infected With SARS-CoV-2.

In the current study, we report on 4 children with confirmed SARS-CoV-2 infection, of which 3 of them were asymptomatic. These patients had both pharyngeal swabs and anal swabs testing during hospital or after discharge. All the 4 children showed long-time positive viral RNA in the stool specimens after pharyngeal swabs turned negative during the follow-up stage, especially in the asymptomatic children. The positive RNA in stool specimens of asymptomatic children last for more than 54 days after admission or 30 days after discharge.

LPS aggravates lung inflammation induced by RSV by promoting the ERK-MMP-12 signaling pathway in mice.

BACKGROUND: RSV can lead to persistent airway inflammation and airway hyperresponsiveness (AHR), and is intimately associated with childhood recurrent wheezing and asthma, but the underlying mechanisms remain unclear. Lipopolysaccharide (LPS) is also implicated in the onset and exacerbation of asthma. However, whether inhalation of LPS can boost airway inflammation induced by RSV is not clear. In this study, we utilized an LPS- and RSV-superinfected mouse model to explore underlying pathogenesis. METHODS: Mice were infected with RSV on day 0 and inoculated with LPS from day 35 to day 41, samples were collected on day 42. Inflammatory cells, lung histopathology and AHR were measured. Cytokines were detected by ELISA and ERK, JNK, p38 was determined by western blot. MMP408, PD98059, SP600125 and SB203580 were used to inhibit MMP-12, ERK, JNK and p38 respectively. RESULTS: LPS exposure superimposed on RSV-infected lungs could lead to more vigorous cellular influx, lung structures damage, augmented AHR and higher MMP-12 levels. Inhibition of MMP-12 or ERK signaling pathway in vivo both diminished LPS-driven airway inflammation and AHR. CONCLUSIONS: Exposure to LPS in RSV-infected mice is associated with enhanced increases in ERK-MMP-12 expression that translates into increased lung inflammation and AHR. These findings contribute novel information to the field investigating the onset of post-RSV bronchiolitis recurrent wheezing as a result of LPS exposure.

A follow-up study of children infected with SARS-CoV-2 from western China.

BACKGROUND: To clarify the characteristic and the duration of positive nucleic acid in children infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), including asymptomatic children. METHODS: A total of 32 children confirmed with SARS-CoV-2 infection between January 24 and February 12, 2020 from four provinces in western China were enrolled in this study and followed up until discharge and quarantine 14 days later. RESULTS: Eleven children (34%) were asymptomatic, among whom six children had normal computed tomographic (CT) scan images. Age and gender were not associated with clinical symptoms or the results of CT scan in children infected with SARS-CoV-2. The concentrations of white blood cells and neutrophils were higher in children with asymptomatic infection than in children with clinical symptoms or CT abnormalities. Patients who presented with CT abnormalities had lower D-dimer or lower total bilirubin than those who had normal CT scan but clinical symptoms. All children recovered and no one died or was admitted to the pediatric intensive care unit (PICU). The mean duration of positive SARS-CoV-2 nucleic acid was 15.4 (SD =7.2) days and similar for both asymptomatic children and children with symptoms or CT abnormalities. We found a significant negative correlation between the lymphocyte count and the duration of positive nucleic acid test. CONCLUSIONS: Children with asymptomatic infection should be quarantined for the same duration as symptomatic patients infected with SARS-CoV-2. The clinical significance and mechanism behind the negative correlation between the number of lymphocytes and the duration of positive SARS-CoV-2 needs further study.

Club cell 10-kDa protein (CC10) inhibits cPLA2/COX2 pathway to alleviate RSV-induced airway inflammation and AHR.

Respiratory syncytial virus (RSV) is the most common viral pathogen causing acute lower respiratory tract infections (LRTI) in infants. Airway epithelial cells, including Club cells, are primary targets of RSV infection. The "Club cell 10-kDa protein" (CC10), produced mainly by Club cells, possesses anti-inflammatory and immunoregulatory properties that are relevant in infection, injury, and allergic reactions. However, its role in the RSV infection is not fully understood. In the clinic, we found that levels of CC10 in the nasopharyngeal aspirates (NPA) of infants, hospitalized with RSV bronchiolitis, were significantly lower than those without LRTI, and were also negatively correlated with the severity of the disease. In BALB/c mice, the CC10 levels in the bronchoalveolar lavage fluid (BALF) were also decreased at the 5th day after infection. When recombinant CC10 was administrated in the mice, RSV-induced airway inflammation and airway hyperresponsiveness (AHR) were alleviated. Similarly, inhibition of cytosolic phospholipase A2 (cPLA2) or cyclooxygenase 2 (COX2), which is a downstream signaling molecule for cPLA2, both alleviated RSV-induced airway inflammation and AHR. Administration of CC10 reduced the phosphorylation of cPLA2 and protein levels of COX-2 in mouse lungs, resulting from infection, thus providing a molecular mechanism for previous reports that CC10 plays a protective role, partly through inhibiting the activity of cPLA2. We conclude that CC10 inhibits the cPLA2/COX2 pathway to alleviate RSV-induced lung airway inflammation and AHR.

High-mobility group box-1 protein from CC10+ club cells promotes type 2 response in the later stage of respiratory syncytial virus infection.

The type 2 immune response, induced by infection of respiratory syncytial virus (RSV), has been linked to asthma development, but it remains unclear how the response is initiated. Here, we reported that the high-mobility group box-1 (HMGB1) protein promotes the type 2 response in the later stage of RSV infection. In mice, we found that type 2 cytokines were elevated in the later stages, which were strongly diminished after administration of anti-HMGB1 antibodies. Further investigation revealed that HMGB1 expression was localized to CC10+ club cells in the lung. In the clinic, levels of HMGB1 in nasopharyngeal aspirates in hospitalized infants with RSV bronchiolitis [median (interquartile range) 161.20 ng/ml (68.06-221.30)] were significantly higher than those without lower respiratory tract infections [21.94 ng/ml (12.12-59.82); P < 0.001]. Moreover, higher levels of HMGB1 correlated with clinical severity. These results reveal a link between viral infection and the asthma-like type 2 responses that are associated with long-term consequences.

Respiratory Syncytial Virus Nonstructural Protein 1 Blocks Glucocorticoid Receptor Nuclear Translocation by Targeting IPO13 and May Account for Glucocorticoid Insensitivity.

Despite their powerful antiinflammatory effect, glucocorticoids have shown no significant clinical benefit in respiratory syncytial virus (RSV)-induced bronchiolitis, the reason for which remains unclear. Upon glucocorticoid binding, the cytoplasmic glucocorticoid receptor (GR) translocates to the nucleus with the help of importin 13 (IPO13). Here, we report that RSV infection reduced GR nuclear translocation in nasopharyngeal aspirates from RSV-infected infants, lungs of infected mice, and A549 cells, which coincided with decreased IPO13 expression. This led to repression of GR-induced antiinflammatory genes, such that dexamethasone failed to suppress airway inflammation and airway hyperresponsiveness in the infected mice. The anti-GR effect of RSV was mediated by viral nonstructural protein 1 , which likely functioned by competing with IPO13 for GR binding. Our findings provide a mechanism for the ineffectiveness of glucocorticoids in RSV-related disease and highlight the potential to target the IPO13-GR axis as a treatment for multiple glucocorticoid-related diseases.

NK cells contribute to persistent airway inflammation and AHR during the later stage of RSV infection in mice.

RSV can lead to persistent airway inflammation and AHR and is intimately associated with childhood recurrent wheezing and asthma, but the underlying mechanisms remain unclear. There are high numbers of NK cells in the lung, which not only play important roles in the acute stage of RSV infection, but also are pivotal in regulating the pathogenesis of asthma. Therefore, in this study, we assumed that NK cells might contribute to persistent airway disease during the later stage of RSV infection. Mice were killed at serial time points after RSV infection to collect samples. Leukocytes in bronchoalveolar lavage fluid (BALF) were counted, lung histopathology was examined, and airway hyperresponsiveness (AHR) was measured by whole-body plethysmography. Cytokines were detected by ELISA, and NK cells were determined by flow cytometry. Rabbit anti-mouse asialo-GM-1 antibodies and resveratrol were used to deplete or suppress NK cells. Inflammatory cells in BALF, lung tissue damage and AHR were persistent for 60 days post-RSV infection. Type 2 cytokines and NK cells were significantly increased during the later stage of infection. When NK cells were decreased by the antibodies or resveratrol, type 2 cytokines, the persistent airway inflammation and AHR were all markedly reduced. NK cells can contribute to the RSV-associated persistent airway inflammation and AHR at least partially by promoting type 2 cytokines. Therefore, therapeutic targeting of NK cells may provide a novel approach to alleviating the recurrent wheezing subsequent to RSV infection.

[Levels of surfactant proteins A and D in bronchoalveolar lavage fluid of children with pneumonia and their relationships with clinical characteristics].

OBJECTIVE: To observe the levels of pulmonary surfactant proteins A and D (SP-A, SP-D) in bronchoalveolar lavage fluid (BALF) of children with pneumonia, and to explore their relationships with clinical characteristics. METHODS: Thirty-five children with pneumonia were enrolled in this study. Differential cell counts were obtained by Countstar counting board. The levels of SP-A and SP-D in BALF were detected using ELISA. RESULTS: In children with pneumonia, SP-D levels were significantly higher than SP-A levels (P<0.001). SP-D levels were negatively correlated with the neutrophil percentage in BALF (r(s)=-0.5255, P<0.01). SP-D levels in BALF in children with increased blood C-reactive protein levels (>8 mg/L) were significantly lower than in those with a normal level of C-reactive protein (P<0.05). Compared with those in children without wheezing, SP-D levels in children with wheezing were significantly lower (P<0.01). There was no correlation between SP-A levels and clinical characteristics. CONCLUSIONS: SP-D levels in BALF are significantly higher than SP-A levels, and have a certain correlation with clinical characteristics in children with pneumonia. As a protective factor, SP-D plays a more important role than SP-A in regulating the immune and inflammatory responses.

[Airway inflammation induced by Poly(I:C) stimulation in the late stage of respiratory syncytial virus infection in mice and its mechanism].

OBJECTIVE: To investigate the pathogenic mechanisms of airway inflammation and recurrent wheezing induced by recurrent respiratory virus infection after respiratory syncytial virus (RSV) infection. METHODS: Sixty-four female BALB/c mice (aged 6-8 weeks) were randomly divided into four groups: control, RSV, Poly(I:C), and RSV+Poly(I:C) (n=16 each). The bronchoalveolar lavage fluid (BALF) was collected on the 3rd day after Poly(I:C) administration, and the total cell number and differential counts in BALF were determined. Hematoxylin-eosin staining was used to observe pulmonary pathological changes. The airway responsiveness was detected. ELISA was used to measure the levels of interferon-γ (IFN-γ), interleukin-4 (IL-4), interleukin-13 (IL-13), matrix metallopeptidase-9 (MMP-9), and tissue inhibitor of metalloproteinase-1 (TIMP-1) in BALF. RESULTS: Compared with the other three groups, the RSV+Poly(I:C) group had significant increases in the total number of inflammatory infiltrating cells in the airway, airway responsiveness, and MMP-9 level in BALF (P<0.05). The RSV+Poly(I:C) group showed more severe pulmonary tissue injuries compared with the control and RSV groups (P<0.01). Compared with the RSV group, the RSV+Poly(I:C) group showed significant reductions in the levels of IL-4 and TIMP-1 in BALF (P<0.01). CONCLUSIONS: Viral re-infection in the late stage of RSV infection may cause an imbalance of MMP-9/TIMP-1 expression and thus contribute to aggravated airway inflammation.

Resveratrol suppresses persistent airway inflammation and hyperresponsivess might partially via nerve growth factor in respiratory syncytial virus-infected mice.

Respiratory syncytial virus (RSV) infection is involved in persistent and recurrent wheezing. There are no effective and safe drugs for the sequelae of persistent wheezing after early bronchiolitis. In this study, we investigated the effect of resveratrol on persistent airway inflammation and airway hyperresponsiveness (AHR) induced by RSV infection. RSV-infected mice were sacrificed at serial time points after infection to collect samples and measure the number of inflammatory cells and levels of interferon-gamma (IFN-γ), nerve growth factor (NGF), and brain-derived neurotrophic factor (BDNF). Airway inflammation, AHR, and the levels of NGF and BDNF were detected after resveratrol administration. Furthermore, Ab-NGF was used to investigate the role of NGF in RSV-induced prolonged airway inflammation and AHR. We found that RSV RNA remained detectable in the lungs of RSV-infected mice on day 60, accompanying persistent airway inflammation and AHR for 60 days. IFN-γ levels in BALF were increased on day 7 but reduced to normal levels by day 14 post-RSV infection, while NGF and BDNF levels gradually increased from day 14 to 60. Furthermore, after resveratrol treatment, the total number of cells in BALF was reduced; the number of inflammatory cells infiltrating the lungs was also lower. Resveratrol attenuated the airway response to methacholine and significantly decreased NGF levels in BALF without affecting BDNF levels. Moreover, airway inflammation and AHR associated with RSV persistence were attenuated after Ab-NGF administration. In all, resveratrol suppresses persistent airway inflammation and AHR might partially through reducing the levels of NGF after RSV infection.

MMP-12-mediated by SARM-TRIF signaling pathway contributes to IFN-γ-independent airway inflammation and AHR post RSV infection in nude mice.

BACKGROUND: Respiratory syncytial virus (RSV) is one of the most frequently observed pathogens during infancy and childhood. However, the corresponding pathogenesis has not been determined to date. We previously demonstrated that IFN-γ plays an important role in RSV pathogenesis, and SARM-TRIF-signaling pathway could regulate the production of IFN-γ. This study is to investigate whether T cells or innate immune cells are the predominant producers of IFN-γ, and further to explore other culprits in addition to IFN-γ in the condition of RSV infection. METHODS: Normal BALB/c mice and nude mice deficient in T cells were infected intranasally with RSV. Leukocytes in bronchoalveolar lavage fluid were counted, lung histopathology was examined, and airway hyperresponsiveness (AHR) was measured by whole-body plethysmography. IFN-γ and MMP-12 were detected by ELISA. MMP408, a selective MMP-12 inhibitor, was given intragastrically. Resveratrol, IFN-γ neutralizing antibody and recombinant murine IFN-γ were administered intraperitoneally. SARM and TRIF protein were semi-quantified by Western blot. siRNA was used to knock-down SARM expression. RESULTS: RSV induced significant airway inflammation and AHR in both mice; IFN-γ was significantly increased in BALB/c mice but not in nude mice. MMP-12 was dramatically increased in both mice but earlier in nude mice. When MMP-12 was inhibited by MMP408, RSV-induced respiratory symptoms were alleviated. SARM was significantly suppressed while TRIF was significantly enhanced in both mice strains. Following resveratrol administration in nude mice, 1) SARM inhibition was prevented, 2) TRIF and MMP-12 were correspondingly down-regulated and 3) airway disorders were subsequently alleviated. Moreover, when SARM was efficiently knocked down using siRNA, TRIF and MMP-12 were markedly enhanced, and the anti-RSV effects of resveratrol were remarkably abrogated. MMP-12 was significantly increased in the IFN-γ neutralizing antibody-treated BALB/c mice but reduced in the recombinant murine IFN-γ-treated nude mice. CONCLUSIONS: MMP-12 can result in at least part of the airway inflammation and AHR independent of IFN-γ. And SARM-TRIF- signaling pathway is involved in regulating the overproduction of MMP-12. To the best of our knowledge, this study is the first that has examined the effects of SARM on MMP-12 and further highlights the potential to target SARM-TRIF-MMP-12 cascades to treat RSV infection.

The genetic variability of glycoproteins among respiratory syncytial virus subtype A in China between 2009 and 2013.

Human respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory tract infections in infants and children under 5years of age. The novel genotype ON1 has a 72-nucleotide duplication, which is the largest duplicated genome portion of RSV. Whether the ON1 genotype will follow the pattern of the BA genotype, which has a 60-nucleotide duplication, and become the predominant RSV-A strain is a global concern. To obtain information regarding the prevalence of the ON1 genotype in Chongqing in Southwestern China, we examined the circulation pattern of RSV-A identified over four consecutive years (June 2009 to August 2013). In this study, 312 (12%) RSV-A strains were isolated from 2601 nasopharyngeal aspirates, and partial G gene was sequenced successfully in 250 isolates. Of the sequenced Chongqing RSV-A isolates, 237 (94.8%) strains were the NA1 genotype, 4 (1.6%) strains were the NA3 genotype, 4 (1.6%) strains were the NA4 genotype, 1 (0.4%) strain was the GA1 genotype, and 4 (1.6%) strains were identified as the ON1 genotype. Analysis of the distribution, phylogeny, and evolution of the ON1 strains that were collected globally until December 2013 revealed that the ON1 genotype has rapidly disseminated across the world under positive selection pressures. Future studies will determine whether this new genotype will continue to spread and become the dominant strain of RSV-A worldwide. These findings may contribute to the understanding of RSV evolution and to the potential development of a vaccine against RSV.