Biology subjects

Carreras, F.

Publications and source records attributed to Carreras, F..

6 recordsLinked to original sources

bioRxiv2026

Functional divergence of regulatory and conventional bovine neutrophils following Mycobacterium bovis infection

Bovine tuberculosis (bTB), due to Mycobacterium bovis (Mb) infection, is a chronic cattle disease and neglected cause of zoonotic tuberculosis. The role of neutrophils in bTB is overlooked. We recently identified a new neutrophil subset in cattle and mice with a similar morphology to conventional inflammatory neutrophils (Nconv). However, unlike Nconv, these regulatory neutrophils (Nreg) express MHC-II at their surface and can suppress lymphocyte proliferation. In this study, we compared the responses of bovine Nconv and Nreg to infection with a virulent Mb strain circulating in France and the attenuated Mb BCG vaccine. Nreg and Nconv had different transcriptional profiles and were differentially activated by Mb infection. Both Nreg and Nconv efficiently killed Mb, but Nreg had higher levels of phagocytosis activity and ROS production. Nreg had higher levels of mitochondrial activity and an ultrastructural organization different from that of Nconv. Our results provide the first insight into the functional characterization of bovine neutrophil subsets during Mb infection and highlight a new layer of complexity in their functional diversity that must be taken into account to improve our understanding of bTB pathophysiology, which is urgently required to improve the management of this costly disease.

immunology↗

bioRxiv2024

From tissue to subcellular level : imaging human precision-cut lung slices (PCLS) to gain insight into pandemic bacterial or viral infections

We describe a method for the generation and deep imaging of human precision-cut lung slices (PCLS). PCLS bridge the gap between in vivo and in vitro studies, providing a robust system for visualizing events from tissue to subcellular levels in the three-dimensional lung environment, with the preservation of all resident cell types and cell-cell interactions. They also constitute a validated model for studying host cell-pathogen interactions. Here, we detail the generation of human PCLS, followed by their infection and imaging by laser scanning confocal microscopy and transmission electron microscopy (TEM). We establish the conditions for ex vivo infection and replication of two pathogens of relevance to human respiratory health: a virus (SARS-CoV-2) and a bacterium (Mycobacterium tuberculosis, Mtb). PCLS can be obtained in a single day, infected the next day, and were successfully cultivated for up to a week in this study. Imaging was performed on fixed samples. The preparation of PCLS took one day for confocal imaging and five days for TEM imaging. All procedures are readily adaptable to explore other pathogens and other species and are easy to implement by users with experience in tissue culture. Some specialist equipment (an Alabama tissue slicer) is required for PCLS generation.

cell biology↗

bioRxiv2023

Neutrophil subsets play dual roles in tuberculosis by producing inflammasome dependent-IL-1β or suppressing T-cells via PD-L1

Neutrophils can be beneficial or deleterious during tuberculosis (TB). Based on the expression of MHC-II and programmed death ligand 1 (PD-L1), we distinguished two functionally and transcriptionally distinct neutrophil subsets in the lungs of mice infected with mycobacteria. Inflammatory [MHC-II-, PD-L1lo] neutrophils produced inflammasome-dependent IL-1{beta} in the lungs in response to virulent mycobacteria and "accelerated" deleterious inflammation, which was highly exacerbated in IFN-{gamma}R-/- mice. Regulatory [MHC-II+, PD-L1hi] neutrophils "brake" inflammation by suppressing T-cell proliferation and IFN-{gamma} production. Such beneficial regulation, which depends on PD-L1, is controlled by IFN-{gamma}R signaling in neutrophils. The hypervirulent HN878 strain from the Beijing genotype curbed PD-L1 expression by regulatory neutrophils, abolishing the braking function and driving deleterious hyper-inflammation in the lungs. These findings add a layer of complexity to the roles played by neutrophils in TB and may explain the reactivation of this disease observed in cancer patients treated with anti-PD-L1. One Sentence SummaryRegulatory and inflammatory neutrophil subsets play inverse roles in tuberculosis.

immunology↗

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

Neutrophils encompass a regulatory subset suppressing T cells in apparently healthy cattle and mice

Neutrophils that reside in the bone marrow are switly recruited from circulating blood to fight infections. For a long time, these first line defenders were considered as microbe killers. However their role is far more complex as cross talk with T cells or dendritic cells have been described for human or mouse neutrophils. In cattle, these new roles are not documented yet. We identified a new subset of regulatory neutrophils that is present in the mouse bone marrow or circulate in cattle blood under steady state conditions. These regulatory neutrophils that display MHC-II on the surface are morphologically indistinguishable from classical MHC-IIneg neutrophils. However MHC-IIpos and MHC-IIneg neutrophils display distinct transcriptomic profiles. While MHC-IIneg and MHC-IIpos neutrophils display similar bacterial phagocytosis or killing activity, MHC-IIpos only are able to suppress T cell proliferation under contact-dependent mechanisms. Regulatory neutrophils are highly enriched in lymphoid organs as compared to their MHC-IIneg counterparts and in the mouse they express PDL-1, an immune checkpoint involved in T-cell blockade. Our results emphasize neutrophils as true partners of the adaptive immune response, including in domestic species. They open the way for discovery of new biomarkers and therapeutic interventions to better control cattle diseases.

immunology↗

bioRxiv2017

Experimental infection of cattle with Mycobacterium tuberculosis isolates shows the attenuation of the human tubercle bacillus for cattle

The Mycobacterium tuberculosis complex (MTBC) is the collective term given to the group of bacteria that cause tuberculosis (TB) in mammals. It has been reported that M. tuberculosis H37Rv, a standard reference MTBC strain, is attenuated in cattle compared to Mycobacterium bovis. However, as M. tuberculosis H37Rv was isolated in the early 1930s, and genetic variants are known to exist, we sought to revisit this question of attenuation of M. tuberculosis for cattle by performing a bovine experimental infection with a recent M. tuberculosis isolate. Here we report infection of cattle using M. bovis AF2122/97, M. tuberculosis H37Rv, and M. tuberculosis BTB1558, the latter isolated in 2008 during a TB surveillance project in Ethiopian cattle. We show that both M. tuberculosis strains caused reduced gross and histopathology in cattle compared to M. bovis. Using M. tuberculosis H37Rv and M. bovis AF2122/97 as the extremes in terms of infection outcome, we used RNA-Seq analysis to explore differences in the peripheral response to infection as a route to identify biomarkers of progressive disease in contrast to a more quiescent, latent infection. Our work shows the attenuation of M. tuberculosis strains for cattle, and emphasizes the potential of the bovine model as a One Health approach to inform human TB biomarker development and post-exposure vaccine development.

immunology↗