Biology subjects

Obino, D.

Publications and source records attributed to Obino, D..

5 recordsLinked to original sources

bioRxiv2024

Infection-on-Chip: an in vitro human vessel to study Neisseria meningitidis colonization and vascular damages

Systemic infections leading to sepsis are life-threatening conditions that remain difficult to treat, and the limitations of current experimental models hamper the development of innovative therapies. Animal models are constrained by species-specific differences, while 2D cell culture systems fail to capture the complex pathophysiology of infection. To overcome these limitations, we developed a laser photoablation-generated, three-dimensional microfluidic model of meningococcal vascular colonization, a human-specific bacterium that causes sepsis and meningitis. Laser photoablation-generated hydrogel engineering allows the reproduction of vascular networks that are major infection target sites, and this model provides the relevant microenvironment reproducing the physiological endothelial integrity and permeability in vitro. By comparing with a human-skin xenograft mouse model, we show that the model system not only replicates in vivo key features of the infection, but also enables quantitative assessment with a higher spatiotemporal resolution of bacterial microcolony growth, endothelial cytoskeleton rearrangement, vascular E-selectin expression, and neutrophil response upon infection. Our device thus provides a robust solution bridging the gap between animal and 2D cellular models, paving the way for a better understanding of disease progression and developing innovative therapeutics.

synthetic biology↗

bioRxiv2022

Inflammation drives age-induced loss of tissue resident macrophages

Low-grade chronic systemic inflammation, or inflammageing, is a hallmark of ageing and a risk factor for both morbidity and mortality in elderly people. Resident macrophages are tissue homeostasis sentinels that are embedded in their tissue of residence since embryonic development, thus been exposed to cumulative tissue insults throughout life. Therefore, resident macrophages, among other immune cells, emerge as potential key contributors to age-associated tissue dysfunction. Contrary to what is currently postulated, we demonstrate here that the pool of embryo-derived resident macrophages exhibits an age-dependent depletion in liver, and other solid organs and that they are not replaced by Hematopoietic Stem Cell (HSCs)-derived monocytes throughout life. Further, we demonstrate that gradual, cumulative inflammation during ageing induces this specific loss of tissue resident macrophages. Preserving a "youthful" density of resident macrophages attenuates classical hallmarks of liver age-associated dysfunction. SummaryThe pool of embryo-derived resident macrophages dwindles with age in most tissues, without compensation from Hematopoietic Stem Cell (HSC)-derived cells. This loss is not due to impaired self-renewal in old tissues but rather to increased cell death, which is driven by sustained inflammation. Attenuating inflammation sensing during ageing prevents age-induce macrophage loss and improves hallmarks of liver ageing.

immunology↗

bioRxiv2022

Anti-thrombotic treatment enhances antibiotic efficiency in a humanized model of meningococcemia

Meningococcal infections remain particularly difficult to treat. Despite antibiotic therapy, the state of the patients often rapidly deteriorates. Early clinical studies suggest that meningococci acquire a form of resistance to antibiotic treatments during infections. Taking advantage of a humanized animal model of infection, we confirm that adherent bacteria become highly resistant to antibiotic treatments as early as 3-6 hours post infection, although fully sensitive in vitro. Within this time frame, meningococci adhere to the endothelium via their type IV pili, proliferate and eventually fill the vessel lumen. Using intravital imaging, we show that rapidly upon infection blood flow is dramatically decreased, thus limiting antibiotic access to infected vessels. Concomitantly, fibrin is deposited inside infected vessels in proximity to bacterial aggregates. Pharmacologically impairing thrombin generation by inhibiting Factor X activity not only improves blood flow in infected vessels, but also enhances the efficacy of the antibiotic treatment. Our results indicate that the combined administration of anticoagulants together with antibiotics might represent a therapeutic approach to treat meningococcal sepsis more efficiently.

pathology↗

bioRxiv2021

Colonization of dermal arterioles by Neisseria meningitidis provides a safe haven from neutrophils

Neisseria meningitidis, a human-specific bacterium, is responsible for meningitis and fatal fulminant systemic disease. Bacteria colonize blood vessels, rapidly causing devastating vascular damage despite a neutrophil-rich inflammatory infiltrate. How this pathogen escapes the neutrophil response is unknown. Using a humanized mouse model, we show that vascular colonization leads to the recruitment of neutrophils, partially reducing bacterial burden and vascular damage. This partial effect is due to the ability of bacteria to indiscriminately colonize capillaries, venules and arterioles, as observed in human samples. In venules, potent neutrophil recruitment allows efficient bacterial phagocytosis. In contrast, in infected capillaries and arterioles adhesion molecules such as E-Selectin are not expressed on the endothelium and intravascular neutrophil recruitment is minimal. These results show that colonization of capillaries and arterioles by N. meningitidis create an intravascular niche that preclude the action of neutrophils, resulting in immune escape and subsequent fulminant progression of the infection.

microbiology↗

bioRxiv2018

Actin filaments regulate microtubule growth at the centrosome.

The centrosome is the main microtubule-organizing centre. It also organizes a local network of actin filaments. However, the precise function of the actin network at the centrosome is not well understood. Here we show that increasing densities of actin filaments at the centrosome of lymphocytes were correlated with reduced amounts of microtubules. Furthermore, lymphocyte activation resulted in centrosomal-actin disassembly and an increase in microtubule number. To further investigate the direct crosstalk between actin and microtubules at the centrosome, we performed in vitro reconstitution assays based on (i) purified centrosomes and (ii) on the co-micropatterning of microtubule seeds and actin filaments. The two assays demonstrated that actin filaments perturb microtubule growth by steric hindrance. Finally, we showed that cell adhesion and spreading leads to lower densities of centrosomal actin thus resulting in higher microtubule growth. Hence we propose a novel mechanism by which the number of centrosomal microtubules is regulated by cell adhesion and actin-network architecture.

cell biology↗