Fosfomycin suppresses chemokine induction in airway epithelial cells infected with respiratory syncytial virus

Development of rapid nucleic acid testing techniques for common respiratory infectious diseases in the Chinese population

Background: Most respiratory viruses can cause serious lower respiratory diseases at any age. Therefore, timely and accurate identification of respiratory viruses has become even more important. This study focused on the development of rapid nucleic acid testing techniques for common respiratory infectious diseases in the Chinese population. Methods: Multiplex fluorescent quantitative polymerase chain reaction (PCR) assays were developed and validated for the detection of respiratory pathogens including the novel coronavirus (SARS-CoV-2), influenza A virus (FluA), parainfluenza virus (PIV), and respiratory syncytial virus (RSV). Results: The assays demonstrated high specificity and sensitivity, allowing for the simultaneous detection of multiple pathogens in a single reaction. These techniques offer a rapid and reliable method for screening, diagnosis, and monitoring of respiratory pathogens. Conclusion: The implementation of these techniques might contribute to effective control and prevention measures, leading to improved patient care and public health outcomes in China. Further research and validation are needed to optimize and expand the application of these techniques to a wider range of respiratory pathogens and to enhance their utility in clinical and public health settings.

Fosfomycin modifies the replication kinetics of bovine alphaherpesvirus-1 and reduces the timing of its protein expression on bovine (MDBK) and human (SH-SY5Y) cell lines

Bovine alphaherpesvirus 1 (BoAHV-1) predisposes cattle to respiratory secondary bacterial infections, which can be treated with the broad-spectrum antibiotic fosfomycin. This drug also suppresses NF-kB activity and pro-inflammatory responses. Therefore, cattle may be exposed to an interaction between the virus and the antibiotic which may have effects on it. The aim of this study was to determine the effect of calcium fosfomycin (580 µg/mL) on BoAHV-1 (moi = 0.1) replication. Two cell lines (MDBK and SH-SY5Y) were used in this study. Our results show that fosfomycin has novel properties. By MTT assay we have shown that it is non-cytotoxic for any of the cell lines. Extracellular and intracellular viral titers demonstrated that fosfomycin has a cell-type and time-dependent effect on BoAHV-1 replication. By direct immunofluorescence it was shown that it reduces the timing of BoAHV-1 protein expression, and by qPCR, we found that its effect on NF-kB mRNA expression depends on the cell type.

Effect of Fosfomycin on Cyclosporine Nephrotoxicity

Fosfomycin (Fos) has emerged as a potential treatment against multidrug-resistant organisms, however, there has been little work done on its influence on calcineurin inhibitor nephrotoxicity (CIN). This study was designed to evaluate the effect of Fos in combination with cyclosporine (CsA) on CIN. Two sets of experiments were undertaken. In the first, Wistar rats received different doses of Fos: 0, 62.5, 125, 250, and 500 mg/kg. In the second, rats were divided into four groups: control, CsA 15 mg/kg s.c., CsA + fosfomycin 62.5 mg/kg (CsA + LF), and CsA + Fos 500 mg/kg (CsA + HF). CsA was administrated daily for 14 days, whereas Fos administration started on the ninth day followed by two more doses, delivered 48 h apart. The administration of different Fos doses did not alter renal function. In contrast, CsA induced arteriolopathy, hypoperfusion, a reduction in the glomerular filtration rate, and downregulation of eNOS, angiotensinogen, and AT1R mRNA levels. Lower doses of Fos did not modify CIN. Instead, the CsA + HF group exhibited greater hypoperfusion, arteriolopathy, and oxidative stress, and increased mRNA levels of pro-inflammatory cytokines. This study shows that Fos administered by itself at different doses did not cause renal injury, but when it was given repeatedly at high dosages (500 mg/kg) in combination with CsA, it increased CIN through the promotion of greater oxidative stress and renal inflammation.

Clarithromycin prevents human respiratory syncytial virus-induced airway epithelial responses by modulating activation of interferon regulatory factor-3

Macrolide antibiotics exert immunomodulatory activity by reducing pro-inflammatory cytokine production by airway epithelial cells, fibroblasts, vascular endothelial cells, and immune cells. However, the underlying mechanism of action remains unclear. Here, we examined the effect of clarithromycin (CAM) on pro-inflammatory cytokine production, including interferons (IFNs), by primary human nasal epithelial cells and lung epithelial cell lines (A549 and BEAS-2B cells) after stimulation by Toll-like receptor (TLR) and RIG-I-like receptor (RLR) agonists and after infection by human respiratory syncytial virus (RSV). CAM treatment led to a significant reduction in poly I:C- and RSV-mediated IL-8, CCL5, IFN-β and -λ production. Furthermore, IFN-β promoter activity (activated by poly I:C and RSV infection) was significantly reduced after treatment with CAM. CAM also inhibited IRF-3 dimerization and subsequent translocation to the nucleus. We conclude that CAM acts a crucial modulator of the innate immune response, particularly IFN production, by modulating IRF-3 dimerization and subsequent translocation to the nucleus of airway epithelial cells. This newly identified immunomodulatory action of CAM will facilitate the discovery of new macrolides with an anti-inflammatory role.

Viral Specific Factors Contribute to Clinical Respiratory Syncytial Virus Disease Severity Differences in Infants

Background

There is a wide range of severity of respiratory syncytial viral (RSV) disease in previously healthy infants. Host factors have been well demonstrated to contribute to disease severity differences. However the possibility of disease severity differences being produced by factors intrinsic to the virus itself has rarely been studied.

Methods

Low-passage isolates of RSV collected prospectively from infants with different degrees of RSV disease severity were evaluated in vitro, holding host factors constant, so as to assess whether isolates induced phenotypically different cytokine/chemokine concentrations in a human lung epithelial cell line. Sixty-seven RSV isolates from previously healthy infants (38 hospitalized for acute RSV infection (severe disease) and 29 never requiring hospitalization (mild disease)) were inoculated into A549, lung epithelial cells at precisely controlled, low multiplicity of infection to mimic natural infection. Cultures were evaluated at 48 hours, 60 hours, and 72 hours to evaluate area under the curve (AUC) cytokine/chemokine induction.

Results

Cells infected with isolates from severely ill infants produced higher mean concentrations of all cytokine/chemokines tested (IL-1α, IL-6, IL-8 and RANTES) at all-time points tested. RSV isolates collected from infants with severe disease induced significantly higher AUCIL-8 and AUCRANTES secretion in infected cultures than mild disease isolates (p=0.028 and p=0.019 respectively). IL-8 and RANTES concentrations were 4 times higher at 48 hours for these severely ill infant isolates. Additionally, 38 isolates were evaluated at all-time points for quantity of virus. RSV concentration significantly correlated with both IL-8 and RANTES at all-time points. Neither cytokine/chemokine concentrations nor RSV concentrations were associated with RSV subgroup.

Discussion

Infants’ RSV disease severity differences may be due in part to intrinsic viral strain-specific characteristics.

Humulone suppresses replication of respiratory syncytial virus and release of IL-8 and RANTES in normal human nasal epithelial cells

Respiratory syncytial virus (RSV) is the major infectious agent causing serious respiratory tract inflammation in infants and young children. However, an effective vaccine and anti-viral therapy for RSV infection have not yet been developed. Hop-derived bitter acids have potent pharmacological effects on inflammation. Therefore, we investigated the effects of humulone, which is the main constituent of hop bitter acids, on the replication of RSV and release of the proinflammatory cytokine IL-8 and chemokine RANTES in RSV-infected human nasal epithelial cells (HNECs). We found that humulone prevented the expression of RSV/G-protein, formation of virus filaments and release of IL-8 and RANTES in a dose-dependent manner in RSV-infected HNECs. These findings suggest that humulone has protective effects against the replication of RSV, the virus assembly and the inflammatory responses in HNECs and that it is a useful biological product for the prevention and therapy for RSV infection.

Clarithromycin suppresses human respiratory syncytial virus infection-induced Streptococcus pneumoniae adhesion and cytokine production in a pulmonary epithelial cell line

Human respiratory syncytial virus (RSV) sometimes causes acute and severe lower respiratory tract illness in infants and young children. RSV strongly upregulates proinflammatory cytokines and the platelet-activating factor (PAF) receptor, which is a receptor for Streptococcus pneumoniae, in the pulmonary epithelial cell line A549. Clarithromycin (CAM), which is an antimicrobial agent and is also known as an immunomodulator, significantly suppressed RSV-induced production of interleukin-6, interleukin-8, and regulated on activation, normal T-cell expressed and secreted (RANTES). CAM also suppressed RSV-induced PAF receptor expression and adhesion of fluorescein-labeled S. pneumoniae cells to A549 cells. The RSV-induced S. pneumoniae adhesion was thought to be mediated by the host cell's PAF receptor. CAM, which exhibits antimicrobial and immunomodulatory activities, was found in this study to suppress the RSV-induced adhesion of respiratory disease-causing bacteria, S. pneumoniae, to host cells. Thus, CAM might suppress immunological disorders and prevent secondary bacterial infections during RSV infection.

The role of SPINK5 in asthma related physiological events in the airway epithelium

BACKGROUND

Genetic studies have shown that variants in SPINK5 may be associated with atopic diseases and asthma. However, the functional role of SPINK5 protein in asthma has not been elucidated.

OBJECTIVES

To determine the effects of SPINK5 on asthma related physiological events such as apoptosis, mucus and cytokine production by epithelial cells.

METHODS

A549 cells were transfected with SPINK5 expression vector and stimulated with increasing doses of hydrogen peroxide and neutrophil elastase (NE) for measurement of cell viability or apoptosis and analysis of mucus production. Cell viability was measured by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5- diphenyl-tetrazolium bromide) assay and apoptosis by Annexin V/PI staining. Levels of IL-4, IL-6, IL-8, IL-12, IL-13, IFNγ, IL-1β and RANTES were determined by ELISA in cell culture supernatants. Mucus production was determined by RT-PCR of the MUC5AC gene and PAS staining in NE treated cells.

RESULTS

Epithelial cells transfected with SPINK5 expression vector produced more IL-6, IL-8 and RANTES compared to non-transfected cells (p < 0.001, p = 0.003, p < 0.001, respectively). Even though cells transfected with SPINK5 vector displayed significantly higher cell death, we have not observed any clear effect of SPINK5 on apoptosis. PAS staining showed that SPINK5 slightly decreased the mucin production induced by neutrophil elastase in A549 cells. However, SPINK5 had no effect on MUC5AC transcription.

CONCLUSION

SPINK5 is an important molecule in asthma. Its role extends beyond its well known protease inhibitor properties.

Fosfomycin suppresses RS-virus-induced Streptococcus pneumoniae and Haemophilus influenzae adhesion to respiratory epithelial cells via the platelet-activating factor receptor

Human respiratory syncytial virus (RSV) sometimes causes acute and severe lower respiratory tract illness in infants and young children. The platelet-activating factor (PAF) receptor, which is a receptor for Streptococcus pneumoniae and Haemophilus influenzae, is upregulated by RSV infection in the pulmonary epithelial cell line A549. Fosfomycin, an antimicrobial agent, significantly suppressed PAF receptor induction by RSV infection at the mRNA and cell surface expression levels. Fosfomycin also suppressed RSV-induced adhesion of fluorescence-labeled S. pneumoniae and H. influenzae cells, as determined by flow cytometry and fluorescence microscopy. The RSV-induced bacterial adhesion was suggested to be host-PAF-receptor and bacterial-phosphocholine mediated. Fosfomycin, which has been shown to exhibit antimicrobial and immunomodulatory activities, was found here to suppress adhesion by disease-causing bacteria. Thus, fosfomycin might prevent secondary bacterial infection during RSV infection.

Pharmacologic advances in the treatment and prevention of respiratory syncytial virus

Currently, only 2 drugs have been approved for the treatment of respiratory syncytial virus (RSV). Palivizumab is a monoclonal antibody for the prevention of RSV in high-risk children. Ribavirin is approved for treatment of severe RSV disease; however, its effectiveness in improving outcomes is questionable. During the past 40 years, many obstacles have delayed the development of safe and effective vaccines and treatment regimens. This article reviews these obstacles and presents the novel development strategies used to overcome many of them. Also discussed are promising new antiviral treatment candidates and their associated mechanism of action, the significant advances made in vaccine development, and exciting, new studies directed at improving outcomes through pharmacologic manipulation of the host response to RSV disease.