Biology subjects

Lacerda Mariano, L.

Publications and source records attributed to Lacerda Mariano, L..

5 recordsLinked to original sources

bioRxiv2024

The Arp2/3 complex maintains genome integrity and survival of epidermal Langerhans cells

Myeloid cells use intracellular actin networks for key cellular processes, including cell migration and chemotaxis, phagocytosis or macropinocytosis, as well as immune synapse formation. However, whether actin networks play any role in the development and/or survival of myeloid cells in tissues remains open. Here, we found that the Arp2/3 complex, which is responsible for the nucleation of branched actin networks, is needed for in vivo maintenance of epidermal Langerhans cells (LCs) throughout life. Mice harboring a genetic deletion of the Arpc4 subunit of the complex in myeloid cells form LC networks at birth, but these cells decline in numbers following a process reminiscent of premature cellular aging. By combining in vivo analyses of LCs with in vitro experiments on bone-marrow-derived dendritic cells, we found that Arpc4-deficient cells manage to progress through the cell cycle but accumulate DNA damage associated with aberrant nuclear shapes, lamina reduction and events of nuclear envelope rupture. These results provide the first evidence for a physiological role of Arp2/3 in maintenance of genome integrity and survival of immune cells in tissues.

cell biology↗

bioRxiv2024

A simple ex vivo bladder infection model permits study of host-pathogen interactions in UTI

Urinary tract infections (UTI) are one of the most common infections, worldwide. To understand mechanisms of UTI pathogenesis and find new treatments, researchers often use animal models, such as mice or rats. However, studying certain phenotypes in animals can be difficult. Additionally, using animals in research comes with significant administrative and ethical challenges. To address these challenges, we developed a simple, reproducible, and cost-effective model to study UTI using donated mouse bladder tissue that would otherwise be discarded. This model allows researchers of all experience levels to study interactions between the host and pathogen in a controlled environment. We tested uropathogenic E. coli colonization and invasion of isolated urothelial sheets from 30 minutes to 24 hours, finding that bacterial burden in our ex vivo model was comparable to in vivo UTI mouse models. To optimize reproducibility, we tested multiple variables, including technical parameters, such as incubator conditions, and biological factors, such as biological sex or prior pregnancy in the donor mouse. This method offers several advantages, including assessment of early host-pathogen interactions, immune cell uptake of bacteria, the impact of age and sex of donor animals in infection, and diverse bacterial strains, mutants, or treatments. In addition, in some countries, sharing material recovered from animals sacrificed for other reasons does not require additional ethical approval by the receiving laboratory, providing a resource for labs without access to animals and reducing administrative burden. Given the breadth of the model with respect to sex, age, mouse and bacterial strain, and the ability to test any parameter that can be included in a 96-well plate, we believe this model will be useful to UTI researchers, with potential application beyond infection or even beyond the bladder to other tissues.

immunology↗

bioRxiv2021

Bladder tissue-resident memory T cells are necessary and sufficient to mediate immunity to recurrent UTI

Urinary tract infection (UTI) is one of the most prevalent human bacterial infections. New therapeutic approaches, including vaccination and immunotherapy, are urgently needed to combat the rapid global dissemination of multidrug-resistant uropathogens. Development of therapies is impeded by an incomplete understanding of memory development during UTI. Here, we found that reducing bacterial load early in infection, by reducing the inoculum or with antibiotics after infection, completely abrogated the protective memory response. We observed a mixed T helper cell polarization, comprised of Th1, Th2, and Th17 T cells, among T cells infiltrating the bladder during primary infection. Thus, we hypothesized that reducing antigen load altered T helper cell polarization leading to poor memory. Surprisingly, however, T helper cell polarization was unchanged in these scenarios. Instead, we uncovered a population of tissue resident memory (TRM) T cells that was significantly reduced in the absence of sufficient antigen. Demonstrating that TRM cells are necessary for immune memory, transfer of lymph node or spleen-derived infection-experienced T cells to naive animals did not confer protection against infection. Supporting that TRM cells are sufficient to protect against recurrent UTI, animals depleted of systemic T cells, or treated with FTY720 to block memory lymphocyte migration from lymph nodes to infected tissue, were equally protected compared to unmanipulated mice against a second UTI. Thus, we uncovered an unappreciated key role for TRM cells in the memory response to bacterial infection in this mucosa, providing a target for non-antibiotic-based immunotherapy and/or new vaccine strategies to prevent recurrent UTI. One Sentence SummaryTRM are necessary and sufficient for memory to recurrent UTI

immunology↗

bioRxiv2020

Functionally distinct resident macrophage subsets differentially shape responses to infection in the bladder

Resident macrophages are abundant in the bladder, playing key roles in immunity to uropathogens. Yet, whether they are heterogeneous, where they come from, and how they respond to infection remain largely unknown. We identified two macrophage subsets in mouse bladders, MacM in the muscle and MacL in the lamina propria, with distinct protein expression and transcriptomes. Using a urinary tract infection model, we validated our transcriptomic analyses, finding that MacM macrophages phagocytosed more bacteria and polarized to a more anti-inflammatory profile, whereas the MacL subset died rapidly during infection. During resolution, monocyte-derived cells contributed to tissue-resident macrophage pools and both subsets acquired transcriptional profiles distinct from naive macrophages. Depletion of these altered macrophages resulted in the induction of a type 1 biased immune response to a second urinary tract infection, improving bacterial clearance. Our study uncovers the biology of resident macrophages and their response to an exceedingly common infection in a largely overlooked organ, the bladder.

immunology↗

bioRxiv2018

Sex differences in IL-17 determine chronicity in male versus female urinary tract infection

Sex-based differences influence incidence and outcome of infectious disease. Women have a significantly greater incidence of urinary tract infection (UTI) than men, yet, conversely, male UTI is more persistent with greater associated morbidity. Mechanisms underlying these sex-based differences are unknown, in part due to a lack of experimental models. We optimized a model to transurethrally infect male mice and directly compared UTI in both sexes. Although both sexes were initially equally colonized by uropathogenic E. coli, only male and testosterone-treated female mice remained chronically infected for up to 4 weeks. Female mice had more robust innate responses, including higher IL-17 expression, and increased {gamma}{delta} T and LTi-like cells in the bladder following infection. Accordingly, neutralizing IL-17 abolished resolution in female mice, identifying the cytokine pathway necessary for bacterial clearance. Our findings support the concept that sex-based responses to UTI contribute to impaired innate immunity in males and provide a rationale for non-antibiotic-based immune targeting to improve the response to UTI.\n\nOne Sentence SummaryWe investigated mechanisms underlying the clinical observation that while urinary tract infection is more prevalent in women, it is more severe in men, observing that in contrast to robust immune responses characterized by IL-17 in female animals, male mice develop chronic infection, following a failure to initiate innate immunity.

immunology↗