Biology subjects

Ren, L.

Publications and source records attributed to Ren, L..

At least 73 records · Page 4Linked to original sources

bioRxiv2021

Spatial and temporal analysis of neutrophil trans-epithelial migration in response to RSV infection

The recruitment of neutrophils to the infected airway occurs early following respiratory syncytial virus (RSV) infection and high numbers of activated neutrophils in airway and blood is associated with the development of severe disease. Here, we investigated whether trans-epithelial migration across primary human airway epithelial cells (AECs) is sufficient and necessary for neutrophil activation during RSV infection. Using flow cytometry, we identified three populations of neutrophils in our in vitro model; those in suspension in basolateral and apical compartments and those that migrated and adhered to AECs. After 1h incubation, the number of adherent neutrophils was significantly greater following RSV infection compared to mock infected. We found that, when migration occurred, neutrophil expression of CD11b, CD62L, CD64, NE and MPO increased in all compartments. However, this did not occur when neutrophils were prevented from migrating. This suggests that the heightened neutrophil activation we detected in the basolateral compartment may be due to reverse migrating neutrophils, as has been suggested by clinical observations. Using live-cell fluorescent microscopy, we then profiled the early temporal and spatial movement and adherence of human neutrophils during migration. Our findings suggest three main phases of early neutrophil recruitment and behaviour in the airways during RSV infection, with neutrophil recruitment, activation and adherence to RSV infected AECs, with clustering, occurring within the first 20 minutes. This work and the model we developed could provide new insight into how neutrophil activation and a dysregulated neutrophil response to RSV mediates disease severity. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=81 SRC="FIGDIR/small/463016v2_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@16639c5org.highwire.dtl.DTLVardef@5aeeacorg.highwire.dtl.DTLVardef@1eb96ceorg.highwire.dtl.DTLVardef@1f9b899_HPS_FORMAT_FIGEXP M_FIG Building on previous work of neutrophil function we propose 3 main phases of early neutrophil recruitment and behaviour in the airways during RSV infection. Phase 1. Initial chemotaxis and adherence: Here unstimulated circulating neutrophils expressing baseline levels of CD11b migrate across infected AECs in response to chemotactic signals in the apical supernatant. Some neutrophils remain adherent to the infected AECs. Phase 2: Activation and reverse migration: once on the apical side of the epithelium, neutrophils increase expression of CD11b and other activation associated markers, and some activated neutrophils undergo reverse migration. Neutrophils with greater expression of CD11b are detected on the basolateral side Phase 3: Amplified chemotaxis and clustering: after 20 minutes, adherent neutrophils begin to rapidly cluster on RSV infected primary airway epithelial cells cultures, mediated by signalling from a dying neutrophil. Drawing created using BioRender.com. C_FIG

immunology↗

bioRxiv2021

An oligosaccharide analog exhibited antifungal activity by misleading cell wall organization via targeting PHR transglucosidases

The fungal cell wall is an ideal target for the design of antifungal drugs. In this study we used an analog of cell wall polymer, a highly deacetylated long-chain chitosan oligosaccharide (HCOS), to test its effect against pathogenic Candida strains. Results showed that HCOS was successfully incorporated into the dynamic cell wall organization process and exhibited an apparent antifungal activity against both plankton and mature fungal biofilm, by impairing the cell wall integrity. Unexpectedly, mechanistic studies suggested that HCOS exerts its activity by interfering with family members of PHR {beta}-(1,3)-glucanosyl transferases and affecting the connection and assembly of cell wall polysaccharides. Furthermore, HCOS showed great synergistic activity with different fungicides against Candida cells, especially those in biofilm. These findings indicated HCOS has a great potential as an antifungal drug or drug synergist and proposed a novel antifungal strategy with structure-specific oligosaccharides mimicking cell wall polysaccharide fragments. IMPORTANCEFungal infections have always been a puzzle in clinical medicine. Only a few antifungal drugs are available for medical usage and the widespread use of antifungal drugs increased the incidence of drug resistance. It is an urgent need for the development of novel treatment strategies against fungal infections. In this study, we proposed a novel strategy targeting to fungal cell wall against C. albicans. To our knowledge, it is the first study to show a cell wall polysaccharide fragment analog integrate into and interfere with the fungal cell wall, indicating a novel antifungal strategy using structure-specific oligosaccharides mimicking cell wall polysaccharide fragments.

microbiology↗

bioRxiv2021

Single-cell transcriptomics for the 99.9% of species without reference genomes

Single-cell RNA-seq (scRNA-seq) is a powerful tool for cell type identification but is not readily applicable to organisms without well-annotated reference genomes. Of the approximately 10 million animal species predicted to exist on Earth, >99.9% do not have any submitted genome assembly. To enable scRNA-seq for the vast majority of animals on the planet, here we introduce the concept of "k-mer homology," combining biochemical synonyms in degenerate protein alphabets with uniform data subsampling via MinHash into a pipeline called Kmermaid. Implementing this pipeline enables direct detection of similar cell types across species from transcriptomic data without the need for a reference genome. Underpinning Kmermaid is the tool Orpheum, a memory-efficient method for extracting high-confidence protein-coding sequences from RNA-seq data. After validating Kmermaid using datasets from human and mouse lung, we applied Kmermaid to the Chinese horseshoe bat (Rhinolophus sinicus), where we propagated cellular compartment labels at high fidelity. Our pipeline provides a high-throughput tool that enables analyses of transcriptomic data across divergent species transcriptomes in a genome- and gene annotation-agnostic manner. Thus, the combination of Kmermaid and Orpheum identifies cell type-specific sequences that may be missing from genome annotations and empowers molecular cellular phenotyping for novel model organisms and species.

bioinformatics↗

bioRxiv2021

Chromatin-interacting transposon RNAs linking to the core trans-inhibition circuitry for embryonic stem cell identity

Transposable DNA sequences constitute more than half of the human and mouse genomes. A large number of non-coding RNAs, named as transposon RNAs, are derived from these transposable elements. The cis-regulatory function of transposable DNA elements, such as LINE-1 and Alu has been largely explored. But the biological roles of transposon RNAs arent well understood. Here, investigations of RNA-chromatin interactions provide us with comprehensive evidence that specific families of transposon RNAs play roles in trans-regulation linking to the core inhibition circuitry for embryonic stem cell identity. Alternative modes of the RNA-DNA hybrid duplex and protein-recruited RNA scaffold are required for the regulatory activities of transposon RNAs. LINE-1 RNAs co-locating with KAP1 form a negative feedback loop stabilizing the transcription of LINE-1 DNA elements via RNA-DNA hybrids. In another way LINE-1 RNAs, together with the reprogramming three factors and Polycomb repressive complexes, participate in the inhibition on dozens of differentiation-relative genes.

genomics↗

bioRxiv2021

Analysis of viral RNA-host protein interactomes enables rapid antiviral drug discovery

RNA viruses including SARS-CoV-2, Ebola virus (EBOV), and Zika virus (ZIKV) constitute a major threat to global public health and society. The interactions between viral genomes and host proteins are essential in the life cycle of RNA viruses and thus provide targets for drug development. However, viral RNA-host protein interactions have remained poorly characterized. Here we applied ChIRP-MS to profile the interactomes of human proteins and the RNA genomes of SARS-CoV-2, EBOV, and ZIKV in infected cells. Integrated interactome analyses revealed interaction patterns that reflect both common and virus-specific host responses, and enabled rapid drug screening to target the vulnerable host factors. We identified Enasidenib as a SARS-CoV-2 specific antiviral agent, and Trifluoperazine and Cepharanthine as broad spectrum antivirals against all three RNA viruses. One Sentence SummaryInteractome analyses of host proteins and the SARS-CoV-2, EBOV, and ZIKV RNA genomes unveil viral biology and drug targets.

microbiology↗

bioRxiv2021

Insulin-like peptide receptor mediated signaling pathways orchestrate regulation of energy homeostasis in the Pacific oyster, Crassostrea gigas

The involvement of insulin/insulin-like growth factor (IIS) signaling pathway in growth regulation of marine invertebrates remains largely unexplored. In this study, we used a fast-growing Pacific oyster (Crassostrea gigas) variety "Haida No.1" as material to unravel the role of IIS system in growth regulation in oysters. Systematic bioinformatics analyses allowed to identify major components of IIS signaling pathway and insulin-like peptide receptor (ILPR) mediated signaling pathways, including PI3K-AKT, RAS-MAPK, and TOR, in C. gigas. Expression levels of the major genes in IIS and its downstream signaling pathways were significantly higher in "Haida No.1" than wild oysters, suggesting their involvement in growth regulation of C. gigas. Expression profiles of IIS and its downstream signaling pathway genes were significantly altered by nutrient abundance and culture temperature. These results suggested that IIS signaling pathway coupled with the ILPR mediated signaling pathways orchestrated energy homeostasis to regulate growth in the Pacific oyster. Research HighlightsO_LIILPR, IRS, IGFBPRP, and IGFALS genes were characterized in the C. gigas. C_LIO_LIMajor genes of IIS signaling pathway were highly expressed in fast-growing C. gigas. C_LIO_LIIIS and downstream pathways participates in energy homeostasis of oysters. C_LIO_LIILPR mediated signaling pathways orchestrate growth regulation in oysters. C_LI

genomics↗

bioRxiv2020

Multiple Mechanisms of HIV-1 resistance to PGT135 in Chinese Subtype B' Slow Progressor

In our study, we describe a slow progressor CBJC515 from whom we constructed pseudoviruses expressing autologous Env. We surprisingly found all the pseudoviruses were resistant to PGT135. By making site-directed mutations and chimeric Env constructs, we found the early 05 strains escaped from PGT135 by losing the N332 glycan site, while the later 06 and 08 strains may escape with the retention of key epitopes through the change of V1/V4/C2 region or by N398/N611 glycan, which was selected as unique N-glycosylation site of CBJC515 compared with CBJC437 whose viruses were also harboring key epitopes but sensitive to PGT135. These findings provide insights into how HIV-1 can escape from N332-directed broadly neutralizing antibody (bNAb) responses without changing the epitope itself, and these ways may be useful to prolong the exposures of bNAb epitopes and contribute to bNAb development. Furthermore, our chimeric experiments also allowed us to explore the co-evolution and retention of functionality among regions. We confirmed that the V1V2 region has a wide range of effectiveness in interfering with the function of envelope protein and the V3 region can promote protein function recovery and buffer the harmful polymorphisms in the other regions contributing to the Env antigenic diversity. These results may provide some clues for the design of vaccines against HIV-1 strains. IMPORTANCEOur findings of mechanisms escaping from PGT135 verified the extensive role of long V1 region in mediating escape from V3-bNAbs. In addition, we also found multiple additional ways suggested that extreme variation may be needed by HIV-1 to escape from PGT135 without changing the epitope itself. Although the V3-glycan bNAb responses are among the most promising vaccine targets, as they are commonly elicited during infection, our findings indicated there may be additional difficulties to be taken into account in immunogen design, such as the consideration of other regions and some glycosylation sites affecting the mask of key epitopes, as well as the selection pressure that may be required by other bNAbs. Our chimeric experiment also highlighted the key role of V3 region in contributing to the maintenance of Env diversity by buffering deleterious polymorphisms, which may be helpful for vaccine design.

immunology↗

bioRxiv2020

Rectal bacteria produce sex pheromones in the male oriental fruit fly

In recent decades, a growing body of literature has indicated that microbial symbionts of insects can modulate their hosts chemical profiles and mate choice decisions. However, there is currently little direct evidence indicate that insect pheromones can be produced by symbionts. Using Bactrocera dorsalis as a model system, we demonstrate that Bacillus sp. in the rectum of male B. dorsalis plays a pivotal role in sex pheromones production. We demonstrate that 2,3,5-trimethylpyrazine (TMP) and 2,3,5,6-tetramethylpyrazine (TTMP) are sex pheromones produced in the male rectums. Mature virgin females can be strongly attracted by TMP and TTMP. TMP and TTMP contents in male rectums can be decreased when rectal bacteria are inhibited with antibiotics. Moreover, Bacillus sp. isolated from male rectum can produce TMP and TTMP when providing with substrates-glucose and threonine, for which the contents are significantly higher in rectums of mature males. These findings highlight the influence of microbial symbionts on insect pheromones and provide an example of direct bacterial production of pheromones in insects.

ecology↗

bioRxiv2020

Identification of potent and safe antiviral therapeutic candidates against SARS-CoV-2

COVID-19 pandemic has infected millions of people with mortality exceeding 300,000. There is an urgent need to find therapeutic agents that can help clear the virus to prevent the severe disease and death. Identifying effective and safer drugs can provide with more options to treat the COVID-19 infections either alone or in combination. Here we performed a high throughput screen of approximately 1700 US FDA approved compounds to identify novel therapeutic agents that can effectively inhibit replication of coronaviruses including SARS-CoV-2. Our two-step screen first used a human coronavirus strain OC43 to identify compounds with anti-coronaviral activities. The effective compounds were then screened for their effectiveness in inhibiting SARS-CoV-2. These screens have identified 24 anti-SARS-CoV-2 drugs including previously reported compounds such as hydroxychloroquine, amlodipine, arbidol hydrochloride, tilorone 2HCl, dronedarone hydrochloride, and merfloquine hydrochloride. Five of the newly identified drugs had a safety index (cytotoxic/effective concentration) of >600, indicating wide therapeutic window compared to hydroxychloroquine which had safety index of 22 in similar experiments. Mechanistically, five of the effective compounds were found to block SARS-CoV-2 S protein-mediated cell fusion. These FDA approved compounds can provide much needed therapeutic options that we urgently need in the midst of the pandemic.Competing Interest StatementThe authors have declared no competing interest.View Full Text

microbiology↗

bioRxiv2020

Comparison of three TaqMan Real-Time Reverse Transcription-PCR assays in detecting SARS-CoV-2

Quick and accurate detection of SARS-CoV-2 is critical for COVID-19 control. Dozens of real-time reverse transcription PCR (qRT-PCR) assays have been developed to meet the urgent need of COVID-19 control. However, methodological comparisons among the developed qRT-PCR assays are limited. In the present study, we evaluated the sensitivity, specificity, amplification efficiency, and linear detection ranges of three qRT-PCR assays, including the assays developed by our group (IPBCAMS), and the assays recommended by WHO and China CDC (CCDC). The three qRT-PCR assays exhibited similar sensitivities, with the limit of detection (LOD) at about 10 copies per reaction (except the ORF 1b gene assay in CCDC assays with a LOD at about 100 copies per reaction). No cross reaction with other respiratory viruses were observed in all of the three qRT-PCR assays. Wide linear detection ranges from 106 to 101 copies per reaction and acceptable reproducibility were obtained. By using 25 clinical specimens, the N gene assay of IPBCAMS assays and CCDC assays performed better (with detection rates of 92% and 100%, respectively) than that of the WHO assays (with a detection rate of 60%), and the ORF 1b gene assay in IPBCAMS assays performed better (with a detection rate of 64%) than those of the WHO assays and the CCDC assays (with detection rates of 48% and 20%, respectively). In conclusion, the N gene assays of CCDC assays and IPBCAMS assays and the ORF 1b gene assay of IPBCAMS assays were recommended for qRT-PCR screening of SARS-CoV-2.Competing Interest StatementThe authors have declared no competing interest.View Full Text

microbiology↗

bioRxiv2020

Single-cell transcriptional atlas of the Chinese horseshoe bat (Rhinolophus sinicus) provides insight into the cellular mechanisms which enable bats to be viral reservoirs

Bats are a major "viral reservoir" in nature and there is a great interest in not only the cell biology of their innate and adaptive immune systems, but also in the expression patterns of receptors used for cellular entry by viruses with potential cross-species transmission. To address this and other questions, we created a single-cell transcriptomic atlas of the Chinese horseshoe bat (Rhinolophus sinicus) which comprises 82,924 cells from 19 organs and tissues. This atlas provides a molecular characterization of numerous cell types from a variety of anatomical sites, and we used it to identify clusters of transcription features that define cell types across all of the surveyed organs. Analysis of viral entry receptor genes for known zoonotic viruses showed cell distribution patterns similar to that of humans, with higher expression levels in bat intestine epithelial cells. In terms of the immune system, CD8+ T cells are in high proportion with tissue-resident memory T cells, and long-lived effector memory nature killer (NK) T-like cells (KLRG1, GZMA and ITGA4 genes) are broadly distributed across the organs. Isolated lung primary bat pulmonary fibroblast (BPF) cells were used to evaluate innate immunity, and they showed a weak response to interferon {beta} and tumor necrosis factor- compared to their human counterparts, consistent with our transcriptional analysis. This compendium of transcriptome data provides a molecular foundation for understanding the cell identities, functions and cellular receptor characteristics for viral reservoirs and zoonotic transmission.

cell biology↗

bioRxiv2020

GuidingNet: revealing transcriptional cofactor and predicting binding for DNA methyltransferase by network regularization

The DNA methyltransferases (DNMTs) (DNMT3A, DNMT3B, and DNMT3L) are primarily responsible for the establishment of genomic locus-specific DNA methylation patterns, which play an important role in gene regulation and animal development. However, this important protein familys binding mechanism, i.e., how and where the DNMTs bind to genome, is still missing in most tissues and cell lines. This motivates us to explore DNMTs and TFs cooperation and develop a network regularized logistic regression model, GuidingNet, to predict DNMTs genome-wide binding by integrating gene expression, chromatin accessibility, sequence, and protein-protein interaction data. GuidingNet accurately predicted methylation experimental data validated DNMTs binding, outperformed single data source based method and sparsity regularized methods, and performed well in within and across tissue prediction for several DNMTs in both human and mouse. Importantly, GuidingNet can reveal transcription co-factors assisting DNMTs for methylation establishment. This provides biological understanding in the DNMTs binding specificity in different tissues and demonstrate the advantage of network regularization. In addition, GuidingNet achieves good performance for chromatin regulators binding other than DNMTs and serves as a useful method for studying chromatin regulator binding and function. The GuidingNet is freely available at https://github.com/AMSSwanglab/GuidingNet. Author summaryDNA methyltransferases (DNMTs) are in charge of the addition of methyl groups to cytosine residues by binding to DNA specific region. However, DNMTs do not have DNA binding domains to recognize specific DNA sequences and an urging question is how DNMTs recognize their binding sites in the genome in different tissues. Here, we propose a network regularized logistic regression model, GuidingNet, for predicting DNMT genome-wide binding by integrating gene expression, chromatin accessibility, sequence, and protein-protein interaction data. The main contribution is to hypothesize that DNMTs interact with transcription factors and are guided by the TF network to bind to DNA, and methylate DNA GuidingNet captures the mechanism of DNMT binding in different tissue contexts and predict DNMTs binding well.

bioinformatics↗

bioRxiv2020

Egg-surface bacteria deter oviposition by the oriental fruit fly Bactrocera dorsalis

Finding a suitable oviposition site is a challenging task for a gravid female fly, since the hatched maggots have limited mobility, making it difficult to find an alternative host. The oriental fruit fly, Bactrocera dorsalis, oviposits on many types of fruits. Maggots hatching in a fruit that is already occupied by conspecific worms will face food competition. Here, we showed that maggot-occupied fruits deter B. dorsalis oviposition and that this deterrence is based on the increased {beta}-caryophyllene concentration in fruits. Using a combination of bacterial identification, volatile content quantification, and behavioural analyses, we demonstrated that the egg-surface bacteria of B. dorsalis, including Providencia sp. and Klebsiella sp., are responsible for this increase in the {beta}-caryophyllene contents of host fruits. Our research shows a type of tritrophic interaction between microorganisms, insects, and insect hosts, which will provide considerable insight into the evolution of insect behavioural responses to volatile compounds.

ecology↗

bioRxiv2020

Cross-reactive neutralization of SARS-CoV-2 by serum antibodies from recovered SARS patients and immunized animals

The current COVID-19 pandemic, caused by a novel coronavirus SARS-CoV-2, poses serious threats to public health and social stability, calling for urgent need for vaccines and therapeutics. SARS-CoV-2 is genetically close to SARS-CoV, thus it is important to define the between antigenic cross-reactivity and neutralization. In this study, we firstly analyzed 20 convalescent serum samples collected from SARS-CoV infected individuals during the 2003 SARS outbreak. All patient sera reacted strongly with the S1 subunit and receptor-binding domain (RBD) of SARS-CoV, cross-reacted with the S ectodomain, S1, RBD, and S2 proteins of SARS-CoV-2, and neutralized both SARS-CoV and SARS-CoV-2 S protein-driven infections. Multiple panels of antisera from mice and rabbits immunized with a full-length S and RBD immunogens of SARS-CoV were also characterized, verifying the cross-reactive neutralization against SARS-CoV-2. Interestingly, we found that a palm civet SARS-CoV-derived RBD elicited more potent cross-neutralizing responses in immunized animals than the RBD from a human SARS-CoV strain, informing a strategy to develop a universe vaccine against emerging CoVs. SummarySerum antibodies from SARS-CoV infected patients and immunized animals cross-neutralize SARS-CoV-2 suggests strategies for universe vaccines against emerging CoVs.

microbiology↗

bioRxiv2020

Humanized Single Domain Antibodies Neutralize SARS-CoV-2 by Targeting Spike Receptor Binding Domain

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread across more than 200 countries and regions, leading to an unprecedented medical burden and live lost. SARS-CoV-2 specific antivirals or prophylactic vaccines are not available. Neutralizing antibodies provide efficient blockade for viral infection and are a promising category of biological therapies. Using SARS-CoV-2 spike RBD as a bait, we have discovered a panel of humanized single domain antibodies (sdAbs). These sdAbs revealed binding kinetics with the equilibrium dissociation constant (KD) of 0.7~33 nM. The monomeric sdAbs showed half maximal inhibitory concentration (IC50) of 0.003~0.3 g/mL in pseudotyped particle neutralization assay, and 0.23~0.50 g/mL in authentic SARS-CoV-2 neutralization assay. Competitive ligand-binding data suggested that the sdAbs either completely blocked or significantly inhibited the association between SARS-CoV-2 RBD and viral entry receptor ACE2. Finally, we showed that fusion of the human IgG1 Fc to sdAbs improved their neutralization activity by tens of times. These results reveal the novel SARS-CoV-2 RBD targeting sdAbs and pave a road for antibody drug development.

microbiology↗

bioRxiv2020

A general model to explain repeated turnovers of sex determination in the Salicaceae

Dioecy, the presence of separate sexes on distinct individuals, has evolved repeatedly in multiple plant lineages. However, the specific mechanisms through which sex systems evolve and their commonalities among plant species remain poorly understood. With both XY and ZW sex systems, the family Salicaceae provides a system to uncover the evolutionary forces driving sex chromosome turnovers. In this study, we performed a genome-wide association study to characterize sex determination in two Populus species, P. euphratica and P. alba. Our results reveal an XY system of sex determination on chromosome 14 of P. euphratica, and a ZW system on chromosome 19 of P. alba. We further assembled the corresponding sex determination regions, and found that their sex chromosome turnovers may be driven by the repeated translocations of a Helitron-like transposon. During the translocation, this factor may have captured partial or intact sequences that are orthologous to a type-A cytokinin response regulator gene. Based on results from this and other recently published studies, we hypothesize that this gene may act as a master regulator of sex determination for the entire family. We propose a general model to explain how the XY and ZW sex systems in this family can be determined by the same RR gene. Our study provides new insights into the diversification of incipient sex chromosome in flowering plants by showing how transposition and rearrangement of a single gene can control sex in both XY and ZW systems.

genomics↗

bioRxiv2020

The Pathogenicity of 2019 Novel Coronavirus in hACE2 Transgenic Mice

Severe acute respiratory syndrome CoV-2 (SARS-CoV-2) caused the Corona Virus Disease 2019 (COVID-19) cases in China has become a public health emergency of international concern (PHEIC). Based on angiotensin converting enzyme 2 (ACE2) as cell entry receptor of SARS-CoV, we used the hACE2 transgenic mice infected with SARS-CoV-2 to study the pathogenicity of the virus. Weight loss and virus replication in lung were observed in hACE2 mice infected with SARS-CoV-2. The typical histopathology was interstitial pneumonia with infiltration of significant lymphocytes and monocytes in alveolar interstitium, and accumulation of macrophages in alveolar cavities. Viral antigens were observed in the bronchial epithelial cells, alveolar macrophages and alveolar epithelia. The phenomenon was not found in wild type mice with SARS-CoV-2 infection. The pathogenicity of SARS-CoV-2 in hACE2 mice was clarified and the Kochs postulates were fulfilled as well, and the mouse model may facilitate the development of therapeutics and vaccines against SARS-CoV-2.

microbiology↗

bioRxiv2019

Neutrophil: Airway Epithelial Interactions Result in Increased Epithelial Damage and Viral Clearance during RSV Infection

Respiratory syncytial virus (RSV) is a major cause of paediatric respiratory disease. Large numbers of neutrophils are recruited into the airways of children with severe RSV disease. It is not clear whether or how neutrophils enhance recovery from disease or contribute to its pathology. Using an in vitro model of the differentiated airway epithelium, we found that addition of physiological concentrations of neutrophils to RSV infected nasal cultures was associated with greater epithelial damage with lower ciliary activity, cilia loss, less tight junction expression (ZO-1) and more detachment of epithelial cells than seen with RSV infection alone. This was also associated with a decrease in infectious virus and fewer RSV positive cells in cultures after neutrophil exposure compared to pre-exposure. Epithelial damage in response to RSV infection was associated with neutrophil activation (within 1h), and neutrophil degranulation with significantly greater cellular expression of CD11b, MPO and higher neutrophil elastase and myeloperoxidase activity in apical surface medias compared to that from mock-infected AECs. We also recovered more apoptotic neutrophils from RSV infected cultures (>40%), compared to <5% in mock infected cultures after 4h. The results of this study could provide important insights into the role of neutrophils in host response in the airway.

immunology↗