Biology subjects

Descamps, D.

Publications and source records attributed to Descamps, D..

9 recordsLinked to original sources

bioRxiv2025

Early-Life Commensal Lung Bacteria Shape Immune Responses and RSV Susceptibility in Neonatal Mice

The lung mucosa during the neonatal period and early infancy is especially susceptible to respiratory syncytial virus (RSV) infection. Respiratory disease severity is strongly influenced by the age at first exposure, which may also affect the trajectory of airway function. Early life represents a critical window for lung development and initial microbiota colonization, both of which shape mucosal immune responses to RSV. The contribution of early lung-colonizing bacterial strains to the establishment of the lung microbiota and susceptibility to RSV infection in neonatal mice remains poorly characterized. In the present study, we showed that early-life primo-colonizing bacterial strains in the mouse lung differentially induce innate immune responses and influence RSV susceptibility in ex vivo models using lung explants and alveolar macrophages (AMs). We identified a specific bacterial strain (strain 17) whose prior exposure enhances type I interferon (IFN-I) responses in AMs upon RSV infection and reduces viral replication both ex vivo and in vivo in lung tissues. Intranasal administration of this strain during early life prevented the development of immunopathological responses upon RSV reinfection in adult mice. Finally, using a translational human airway epithelium model, we demonstrated that pre-exposure to strain 17 restricts RSV spread without cytotoxicity, likely via enhanced {beta}-defensin 2 production. These findings highlight the potential of early-life microbiota modulation as a promising intervention for preventing RSV disease and its long-term respiratory consequences. Author summaryRespiratory syncytial virus (RSV) is a major cause of severe respiratory infections in newborns and infants, a period during which the lungs and immune system are still maturing. Simultaneously, the respiratory tract undergoes its first microbial colonization by so-called primo-colonizing bacteria -- the first bacterial species to establish themselves on neonatal lower respiratory mucosal surfaces. These early microbial pioneers may play an unsuspected role in shaping how the immature immune system responds to viral threats. In this study, we investigated whether these early lung-colonizing strains influence RSV susceptibility. Using neonatal mouse models, lung explants, and alveolar macrophages, we found that distinct bacterial strains trigger markedly different innate immune responses. Prior exposure to one strain in particular, strain 17, was associated with enhanced type I interferon responses, reduced viral replication, and protection against harmful inflammation upon RSV reinfection later in life. In a human airway epithelium model, pre-exposure to strain 17 also restricted RSV spread without tissue damage, potentially through increased {beta}-defensin 2 production. These findings provide proof-of-concept that the bacterial strains establishing in the neonatal lung can influence future immune reactivity and antiviral responses, and suggest that early-life respiratory microbiota modulation could represent a promising strategy to prevent severe RSV disease.

immunology↗

bioRxiv2025

A dual interaction between RSV NS1 and MED25 ACID domain reshapes antiviral responses

Respiratory syncytial virus (RSV), the most common cause of bronchiolitis and pneumonia in infants, elicits a remarkably weak innate immune response. This is partly due to the type I interferon (IFN-I) antagonism of the non-structural RSV NS1 protein. It was recently suggested that NS1 could modulate host transcription via an interaction with the MED25 subunit of the Mediator complex. Previous work emphasized the role of the NS1 C-terminal helix 3 for recruitment of the MED25 ACID domain, a target of transcription factors (TFs). Here we show that the NS1 /{beta} core domain binds to MED25 ACID, and acts cooperatively with NS1 3 to achieve nanomolar affinity. This strong interaction is rationalized by the dual NS1 binding site on MED25 ACID predicted by AlphaFold3, which overlaps with the two canonical binding interfaces of TF transactivation domains (TADs), H1 and H2. By NMR, we confirmed that the NS1 /{beta} core domain targets the H2 interface. Several single amino acid NS1 /{beta} core domain mutations displayed reduced affinity for MED25 ACID, both in vitro and in cellula, at a comparable extent to the deletion of NS1 3. These mutations resulted in attenuated replication of recombinant RSV (rRSV) and increased expression of several antiviral interferon-stimulated genes (ISG) in interferon-competent cells. In MED25 knockdown cells, rRSV-mCherry replication was further attenuated, in line with the upregulation of IFT1 and ISG15 ISGs. The difference between WT and NS1 mutant rRSV-mCherry was partially lost, suggesting that RSV uses MED25 to control antiviral responses, by a mechanism involving the NS1-MED25 ACID complex. The strong interaction and the extended binding surface of NS1 on MED25 ACID provide evidence for a mechanism, where NS1 blocks access of transcription factors to MED25 ACID, and thereby MED25 mediated transcription activation. Author SummaryRespiratory syncytial virus (RSV) is a major pathogen for acute lower respiratory infections in infants and in the elderly. RSV elicits a remarkably weak immune response. It has developed a unique strategy to counteract the immune system, by encoding two small multifunctional proteins, RSV NS1 and NS2. NS1 is involved in interferon antagonism in the cytosol. Recently NS1 was shown to modulate host transcription in the nucleus. However, the mechanisms underpinning this function are not fully clear. Here we focus on the interplay between NS1 and the cellular MED25 coactivator protein, which can contribute to the antiviral response by activating several innate immune response genes. The MED25 C-terminal ACtivator Interacting Domain (ACID), a target of cellular transcription factors (TF), is a key feature for this function. To investigate the impact of MED25 hijacking by NS1, we combined in vitro biophysical experiments and cellular assays to probe the relationship between the stability of the NS1-MED25 ACID complex and RSV replication as well as antiviral responses. Our results suggest that this interaction is correlated with antiviral response antagonism, probably by hindering TFs to interact with MED25-ACID. This knowledge might pave the way for antiviral strategies aimed at stimulating appropriate immune responses.

pathology↗

bioRxiv2021

Depletion of TAX1BP1 amplifies innate immune responses during respiratory syncytial virus infection

Respiratory syncytial virus (RSV) is the main cause of acute respiratory infections in young children, and also has a major impact in the elderly and immunocompromised people. In the absence of vaccine or efficient treatment, a better understanding of RSV interactions with the host antiviral response during infection is needed. Previous studies revealed that cytoplasmic inclusion bodies (IBs) where viral replication and transcription occur could play a major role in the control of innate immunity during infection by recruiting cellular proteins involved in the host antiviral response. We recently showed that the morphogenesis of IBs relies on a liquid-liquid phase separation mechanism depending on the interaction between viral nucleoprotein (N) and phosphoprotein (P). These scaffold proteins are expected to play a central role in the recruitment of cellular proteins to IBs. Here, we performed a yeast two-hybrid screen using RSV N protein as a bait, and identified the cellular protein TAX1BP1 as a potential partner of N. This interaction was validated by pulldown and immunoprecipitation assays. We showed that TAX1BP1 suppression has only a limited impact on RSV infection in cell cultures. On the contrary, in vivo experiments showed that RSV replication is decreased in TAX1BP1KO mice, whereas the production of inflammatory and antiviral cytokines is enhanced. In vitro infection of either wild-type or TAX1BP1KO alveolar macrophages confirmed that the innate immune response to RSV infection is enhanced in the absence of TAX1BP1. Altogether, our results suggest that RSV could hijack TAX1BP1 to restrain the host immune response during infection. ImportanceRespiratory syncytial virus (RSV), which is the leading cause of lower respiratory tract illness in infants, still remains a medical problem in the absence of vaccine or efficient treatment. This virus is also recognized as a main pathogen in the elderly and immunocompromised people, and the occurrence of co-infections (with other respiratory viruses and bacteria) amplifies the risks of developing respiratory distress. In this context, a better understanding of the pathogenesis associated to viral respiratory infections, which depends on both viral replication and the host immune response, is needed. The present study reveals that the cellular protein TAX1BP1, which interacts with the RSV nucleoprotein N, participates in the control of the innate immune response during RSV infection, suggesting that N-TAX1BP1 interaction represents a new target for the development of antivirals.

microbiology↗

bioRxiv2021

Mycobacterial infection of precision cut lung slices reveals that the type 1 interferon pathway is locally induced by Mycobacterium bovis but not M. tuberculosis in different cattle breeds

Tuberculosis exacts a terrible toll on human and animal health. While Mycobacterium tuberculosis (Mtb) is restricted to humans, Mycobacterium bovis (Mb) is present in a large range of mammalian hosts. In cattle, bovine TB (bTB) is a notifiable disease responsible for important economic losses in developed countries and underestimated zoonosis in the developing world. Early interactions that take place between mycobacteria and the lung tissue early after aerosol infection govern the outcome of the disease. In cattle, these early steps remain poorly characterized. The precision-cut lung slice (PCLS) model preserves the structure and cell diversity of the lung. We developed this model in cattle in order to study the early lung response to mycobacterial infection. In situ imaging of PCLS infected with fluorescent Mb revealed bacilli in the alveolar compartment, adjacent or inside alveolar macrophages (AMPs) and in close contact with pneumocytes. We analyzed the global transcriptional lung inflammation signature following infection of PCLS with Mb and Mtb in two French beef breeds: Blonde dAquitaine and Charolaise. Whereas lungs from the Blonde dAquitaine produced high levels of mediators of neutrophil and monocyte recruitment in response to infection, such signatures were not observed in the Charolaise in our study. In the Blonde dAquitaine lung, whereas the inflammatory response was highly induced by two Mb strains, AF2122 isolated from cattle in the UK and Mb3601 circulating in France, the response against two Mtb strains, H37Rv the reference laboratory strain and BTB1558 isolated from zebu in Ethiopia, was very low. Strikingly, the type I interferon pathway was only induced by Mb but not Mtb strains indicating that this pathway may be involved in mycobacterial virulence and host tropism. Hence, the PCLS model in cattle is a valuable tool to deepen our understanding of early interactions between lung host cells and mycobacteria. It revealed striking differences between cattle breeds and mycobacterial strains. This model could help deciphering biomarkers of resistance versus susceptibility to bTB in cattle as such information is still critically needed for bovine genetic selection programs and would greatly help the global effort to eradicate bTB.

immunology↗

bioRxiv2020

New look at RSV infection : tissue clearing and 3D imaging of the entire mouse lung at cellular resolution.

BackgroundRespiratory Syncytial Virus (RSV) is the major cause of severe acute respiratory tract illness in young children worldwide and a main pathogen for the elderly and immune-compromised people. In the absence of vaccines or effective treatments, a better characterization of the pathogenesis of RSV infection is required. To date, the pathophysiology of the disease and its diagnosis mostly relied on chest x-ray and genome detection in nasopharyngeal swabs. The development of new imaging approaches is instrumental to further the description of RSV spread, virus-host interactions and related acute respiratory disease, at the level of the entire lung. MethodsBy combining tissue clearing, 3D microscopy and image processing, we developed a novel visualization tool of RSV infection in undissected mouse lungs. ResultsWhole tissue analysis allowed the identification of infected cell subtypes, based on both morphological traits and position within the cellular network. Furthermore, 3D imaging was also valuable to detect the cytoplasmic viral factories, also called inclusion bodies, a hallmark of RSV infection. ConclusionsWhole lung clearing and 3D deep-imaging represents an unprecedented visualization method of infected lungs to allow insight into RSV pathophysiology and improve the 2D histology analyses.

pathology↗

bioRxiv2020

The microbiota plays a critical role in the reactivity of lung immune components to innate ligands

The microbiota contributes to shaping efficient and safe immune defenses in the gut. However, little is known about the role of the microbiota in the education of pulmonary innate immune responses. Here, we tested whether the endogenous microbiota can modulate reactivity of pulmonary tissue to pathogen stimuli by comparing the response of specific pathogen-free (SPF) and germ-free (GF) mice. Using SPF and GF mice intranasally exposed to lipopolysaccharide (LPS), a component of Gram-negative bacteria, we observed earlier and greater inflammation in the pulmonary compartment of GF mice than that of SPF mice. Toll-like receptor 4 (TLR4) was more abundantly expressed in the lungs of GF mice than those of SPF mice at steady state, which could predispose the innate immunity of GF mice to strongly react to environmental stimuli. Lung explants were stimulated with different TLR agonists or infected with the human airways pathogen, respiratory syncytial virus (RSV), resulting in greater inflammation under almost all conditions for the GF explants. Finally, alveolar macrophages (AM) from GF mice presented a higher innate immune response upon RSV infection than those of SPF mice. Overall, these data suggest that the presence of microbiota in SPF mice induced a process of innate immune tolerance in the lungs by a mechanism which remains to be elucidated. Our study represents a step forward to establishing the link between the microbiota and the immune reactivity of the lungs. Plain Language summaryMicrobiota represents an important partner of immunologic system at the interface between immune cells and epithelium. It is well known, notably in the gut, that the microbiota contributes in shaping efficient and safe defenses. However, little is known about the role of the microbiota in the education of pulmonary innate immune responses. In this study, we postulate that endogenous microbiota could dampen an excessive reactivity of pulmonary tissue to external stimuli. Thus, we sought to study the innate immune reaction switched on by viral or bacterial ligands in respiratory tract cells coming from mice with or without microbiota (germ-free condition, GF). Altogether, our results show a higher inflammatory reaction in GF condition. This study represents a step forward to better establish the link between the microbiota and the reactivity of the lung tissue. Not only these data demonstrate that the microbiota educates the pulmonary innate immune system, but also contributes the emerging concept of using respiratory commensal bacteria as potential next-generation probiotics to prevent susceptibility to respiratory diseases.

immunology↗

bioRxiv2020

Multicenter comparison of the Cobas 6800 system with the RealStar RT-PCR kit for the detection of SARS-CoV-2

BackgroundRT-PCR testing is crucial in the diagnostic of SARS-CoV-2 infection. The use of reliable and comparable PCR assays is a cornerstone to allow use of different PCR assays depending on the local equipment. In this work, we provide a comparison of the Cobas(R) (Roche) and the RealStar(R) assay (Altona). MethodsAssessment of the two assays was performed prospectively in three reference Parisians hospitals, using 170 clinical samples. They were tested with the Cobas(R) assay, selected to obtain a distribution of cycle threshold (Ct) as large as possible, and tested with the RealStar assay with three largely available extraction platforms: QIAsymphony (Qiagen), MagNAPure (Roche) and NucliSENS-easyMag (BioMerieux). ResultsOverall, the agreement (positive for at least one gene) was 76%. This rate differed considerably depending on the Cobas Ct values for gene E: below 35 (n = 91), the concordance was 99%. Regarding the positive Ct values, linear regression analysis showed a determination correlation (R2) of 0.88 and the Deming regression line revealed a strong correlation with a slope of 1.023 and an intercept of -3.9. Bland-Altman analysis showed that the mean difference (Cobas(R) minus RealStar(R)) was + 3.3 Ct, with a SD of + 2.3 Ct. ConclusionsIn this comparison, both RealStar(R) and Cobas(R) assays provided comparable qualitative results and a high correlation when both tests were positive. Discrepancies exist after 35 Ct and varied depending on the extraction system used for the RealStar(R) assay, probably due to a low viral load close to the detection limit of both assays.

microbiology↗

bioRxiv2019

Trivalent cocktail of de novo designed immunogens enables the robust induction and focusing of functional antibodies in vivo

De novo protein design has been successful in expanding the natural protein repertoire. However, most de novo proteins lack biological function, presenting a major methodological challenge. In vaccinology, the induction of precise antibody responses remains a cornerstone for next-generation vaccines. Here, we present a novel protein design algorithm, termed TopoBuilder, with which we engineered epitope-focused immunogens displaying complex structural motifs. Both in mice and non-human primates, cocktails of three de novo designed immunogens induced robust neutralizing responses against the respiratory syncytial virus. Furthermore, the immunogens refocused pre-existing antibody responses towards defined neutralization epitopes. Overall, our de novo design approach opens the possibility of targeting specific epitopes for vaccine and therapeutic antibody development, and more generally will be applicable to design de novo proteins displaying complex functional motifs.

bioengineering↗

bioRxiv2018

Boosting subdominant neutralizing antibody responses with a computationally designed epitope-focused immunogen

Throughout the last decades, vaccination has been key to prevent and eradicate infectious diseases. However, many pathogens (e.g. respiratory syncytial virus (RSV), influenza, dengue and others) have resisted vaccine development efforts, largely due to the failure to induce potent antibody responses targeting conserved epitopes. Deep profiling of human B-cells often reveals potent neutralizing antibodies that emerge from natural infection, but these specificities are generally subdominant (i.e., are present in low titers). A major challenge for next-generation vaccines is to overcome established immunodominance hierarchies and focus antibody responses on crucial neutralization epitopes. Here, we show that a computationally designed epitope-focused immunogen presenting a single RSV neutralization epitope elicits superior epitope-specific responses compared to the viral fusion protein. In addition, the epitope-focused immunogen efficiently boosts antibodies targeting the Palivizumab epitope, resulting in enhanced neutralization. Overall, we show that epitope-focused immunogens can boost subdominant neutralizing antibody responses in vivo and reshape established antibody hierarchies.

immunology↗