Lumbreras, M. | Search bioRxiv

bioRxiv2025

Protective efficacy of mutant strains of Borrelia burgdorferi as potential reservoir host-targeted biologics against Lyme disease

Lyme disease (LD), caused by Borrelia burgdorferi (Bb), is the most common vector-borne disease in the United States. Novel strategies to control transmission of Bb to humans via ticks are critical for prevention of LD. One such strategy is to leverage non-infectious mutant strains of Bb for pathogen-derived biologics to block Bb transmission during the natural infectious cycle. Deletion of Borrelia host-adaptation Regulator ({Delta}badR) and replacement of 8 conserved residues with alanines in Carbon Storage Regulator A of Bb (8S) resulted in mutants, with upregulation of RpoS and several immunogenic lipoproteins, that were incapable of colonization in C3H/HeN mice. Intradermal vaccination of mice with the live mutant strains resulted in significant anti-borrelial antibody responses and a reduction in Bb acquisition by naive Ixodes scapularis larvae following needle challenge with Bb B31-A3. While vaccination with {Delta}badR mutant conferred significant reduction in the percentage of infected mice, ML23 and 8S mutants conferred variable levels of protection. Comparative proteomic analysis of Purified Borrelial Lipoproteins (PBLs) from parental and mutant strains revealed similar and unique antigenic components. Infection derived mouse serum and serum from Lyme disease patients exhibited reactivity to lysates and PBLs from these mutants. Immunization with PBLs from B31-A3 and 8S strains conferred significant protection against challenge with Bb infected nymphs, underscoring the utility of PBLs as protective formulations. Overall, non-infectious mutant strains, or their lipoproteins, can be exploited as biologics to block the acquisition of Bb by naive larvae from reservoir hosts, disrupting the enzootic transmission cycle of the agent of Lyme disease.

microbiology↗

bioRxiv2023

A new tractable method for generating Human Alveolar Macrophage Like cells in vitro to study lung inflammatory processes and diseases

Alveolar macrophages (AMs) are unique lung resident cells that contact airborne pathogens and environmental particulates. The contribution of human AMs (HAM) to pulmonary diseases remains poorly understood due to difficulty in accessing them from human donors and their rapid phenotypic change during in vitro culture. Thus, there remains an unmet need for cost-effective methods for generating and/or differentiating primary cells into a HAM phenotype, particularly important for translational and clinical studies. We developed cell culture conditions that mimic the lung alveolar environment in humans using lung lipids, i.e., Infasurf (calfactant, natural bovine surfactant) and lung-associated cytokines (GM-CSF, TGF-{beta}, and IL-10) that facilitate the conversion of blood-obtained monocytes to an AM-Like (AML) phenotype and function in tissue culture. Similar to HAM, AML cells are particularly susceptible to both Mycobacterium tuberculosis and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. This study reveals the importance of alveolar space components in the development and maintenance of HAM phenotype and function, and provides a readily accessible model to study HAM in infectious and inflammatory disease processes, as well as therapies and vaccines. IMPORTANCEMillions die annually from respiratory disorders. Lower respiratory track gas-exchanging alveoli maintain a precarious balance between fighting invaders and minimizing tissue damage. Key players herein are resident AMs. However, there are no easily accessible in vitro models of HAMs, presenting a huge scientific challenge. Here we present a novel model for generating AML cells based on differentiating blood monocytes in a defined lung component cocktail. This model is non-invasive, significantly less costly than performing a bronchoalveolar lavage, yields more AML cells than HAMs per donor and retains their phenotype in culture. We have applied this model to early studies of M. tuberculosis and SARS-CoV-2. This model will significantly advance respiratory biology research.

immunology↗