Biology subjects

Bounab, B.

Publications and source records attributed to Bounab, B..

3 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↗