Biology subjects

da Silva, P.

Publications and source records attributed to da Silva, P..

9 recordsLinked to original sources

bioRxiv2026

Brain-resident myeloid cells promote rapid leukocyte adhesion in leptomeningeal vessels after anti-Aβ immunotherapy

Anti-amyloid {beta} (A{beta}) immunotherapy improves cognitive outcomes in Alzheimer's disease (AD) but is associated with amyloid-related imaging abnormalities (ARIA), through poorly understood mechanisms. To define how anti-A{beta} antibodies acutely engage brain immune and vascular compartments, we developed a longitudinal in vivo two-photon imaging platform to track microglial dynamics, peripheral immune cell recruitment, and vascular responses in APP/PS1 mice. Anti-A{beta} antibodies, including aducanumab and lecanemab, rapidly initiated microglial activation and spatial reorganization within 24 hours of dosing, with recruitment to plaque-associated regions, stabilizing plaque growth. Aducanumab and lecanemab also triggered a rapid and transient cerebrovascular immune response characterized by rolling and adhesion of peripheral immune cells along leptomeningeal vessels, accompanied by endothelial activation. Immune cell characterization revealed recruitment of innate immune cells (Iba1Ki67 monocytes and Ly6G neutrophils) and proliferative CD3 T cells into the vascular compartment following treatment. Prophylactic treatment with high-dose dexamethasone reduced the number of adherent cells without affecting microglial activation. Depletion of brain-resident immune cells similarly reduced peripheral immune cell recruitment, supporting their contribution to leukocyte recruitment. Postmortem brain tissue from an AD patient treated with lecanemab showed higher proliferation-associated monocyte signature scores, suggesting translational relevance to the proliferative myeloid response observed in our mouse models. These findings demonstrate that anti-A{beta} immunotherapy rapidly initiates a coordinated central and peripheral immune response at the leptomeningeal interface. These early immune-vascular interactions represent a plausible initiating mechanism for ARIA and provide a mechanistic framework to guide strategies for mitigating ARIA risk

neuroscience↗

bioRxiv2026

Neuronal DNA repair mediates systemic mitochondrial maintenance through acetylcholine signaling

DNA repair defects such as Nucleotide Excision Repair (NER) mutations can lead to progeroid syndromes characterized by growth retardation and accelerated aging with distinct tissue type specific pathologies. DNA damage induced dysfunction of specific cell types can impair the organisms overall function. It is unknown whether, in reverse, DNA repair in specific tissues can have non-cell-autonomous consequences on other tissues carrying DNA damage. To explore the organismal consequences of cell type specific DNA repair, we restricted NER activity to specific tissues and monitored consequences on organismal health in C. elegans. Unexpectedly, we observed that tissue specific DNA repair is sufficient to improve overall DNA damage resistance. Strikingly, the sole NER activity in neurons is sufficient to provide similar overall DNA damage resistance as whole body NER. We show that this systemic DNA damage resilience is mediated by neuronal Acetylcholine signaling that promotes the maintenance of mitochondrial activity throughout the organism.

genetics↗

bioRxiv2026

Single-cell RNA sequencing of CTLA-4 and PD-1 blockade in pulmonary paracoccidioidomycosis highlights a protective transcriptional program mediated by activated Th17 cells, neutrophils and macrophages

Pulmonary paracoccidioidomycosis (PCM) relies on a finely balanced lung-immune network in which Th17, Treg, neutrophils, and macrophages orchestrate fungal control and tissue integrity. Furthermore, within the context of single-cell sequencing, little is known about how immune checkpoint inhibition modulates this balance during systemic mycosis. In a previous study we verified that the blockade of checkpoint molecules (CTLA-4 and PD-1) restores protective immunity that reduces fungal loads, tissue pathology and mortality of infected mice. Here, we have further studied this model by single-cell RNA sequencing on lung leukocytes from mice infected with Paracoccidioides brasiliensis and treated with anti-CTLA-4 or anti-PD-1 antibodies to define the cellular and molecular consequences of checkpoint blockade in vivo. We generated a high-resolution atlas covering T cells, neutrophils, macrophages/monocytes, B cells, NK cells, and epithelial subsets. Checkpoint inhibition consistently remodeled the CD4 T cell compartment toward a Th17-enriched program, with reduced interleukin-10 expressing Treg frequencies and a prominent interleukin-17A (IL-17), C-C chemokine receptor type 2, CXC chemokine (CXC) receptor type 6, CD44 (Il17aCcr2Cxcr6Cd44) signature. This shift was accompanied by the expansion and activation of neutrophils and macrophages expressing tumor necrosis factor and chemokines (including CXC motif chemokine ligand (Cxcl1, Cxcl2 and Ccl4), microbicidal-associated genes (S100 calcium-binding protein A8 and A9), and regulatory mediators such as secretory leukocyte protease inhibitor and interleukin-15. Ligand-receptor and trajectory analyses revealed a reinforced Th17-myeloid communication axis, particularly under CTLA-4 blockade, converging on IL17-centered inflammatory circuits while attenuating canonical Treg checkpoints (cytotoxic T-lymphocyte-associated protein 4, programmed cell death protein 1, interleukin-10). Together, these data demonstrate that anti-CTLA-4 and anti-PD-1 immunotherapies profoundly rewire the lung-immune microenvironment during PCM, amplifying effector Th17-neutrophil-macrophage networks that benefits protective antifungal activity Our work provides a mechanistic framework for evaluating immune checkpoint inhibitors in chronic fungal infections.

immunology↗

bioRxiv2024

Th17 cells require the DNA repair sensor XPC to control oxidative DNA damage

Th17 cells are critical for mucosal immunity, producing IL-17A, IL-17F, and IL-22, but dysregulated Th17 responses are implicated in autoimmune diseases. Despite their susceptibility to oxidative stress in certain conditions, Th17 cells exhibit reduced oxidative DNA damage and cell death compared to other T helper subsets. However, the mechanisms that protect Th17 cells from oxidative stress are poorly understood. Here, we identify Xeroderma Pigmentosum Complementation Group C (XPC) as a key regulator of DNA repair and genomic stability in Th17 cells. In XPC-deficient mice, we demonstrate that the absence of XPC impairs Th17 differentiation, as evidenced by reduced expression of key differentiation markers, including Rorc and Il17a, along with decreased IL-17A production. This deficiency leads to increased oxidative stress, DNA damage, and a metabolic shift from glycolysis to oxidative phosphorylation. Moreover, the transcription factor BATF directly regulates XPC expression, linking the BATF-XPC axis to the maintenance of Th17 cell function. Importantly, we find that restoring antioxidant capacity with N-Acetylcysteine (NAC) rescues IL-17A production and reduces DNA damage in XPC-deficient Th17 cells. Mechanistically, we find that XPC interacts with OGG1, a DNA glycosylase involved in the repair of oxidative DNA damage, highlighting XPCs role in maintaining genomic integrity during Th17 cell differentiation. Our findings reveal a previously unrecognized role for XPC in protecting Th17 cells from oxidative stress, ensuring their proper differentiation and function, with potential implications for targeting DNA repair pathways in autoimmune and inflammatory diseases.

immunology↗

bioRxiv2021

The aphid BCR4 structure and activity uncover a new defensin peptide superfamily

Aphids (Hemiptera: Aphidoidea) are among the most injuring insects for agricultural plants and their management is a great challenge in agronomical research. A new class of proteins, called Bacteriocyte-specific Cysteine-Rich (BCR), provides an alternative to chemical insecticides for pest control. BCRs have been initially identified in the pea aphid Acyrthosiphon pisum. They are small disulfide bond-rich proteins expressed exclusively in aphid bacteriocytes, the insect derived cells that host intracellular symbiotic bacteria. Here, we show that one out of the A. pisum BCRs, BCR4, displays an outstanding insecticidal activity against the pea aphid, impairing insect survival and nymphal growth, providing evidence for its potential use as a new biopesticides. Our comparative genomics and phylogenetic analysis indicate that BCRs seem restricted to the aphid lineage. The 3D structure of the BCR4 reveals that this peptide belongs to a yet unknown structural class of peptides and defines a new superfamily of defensins.

biochemistry↗

bioRxiv2021

Zika Virus Infection of Murine and Human Neutrophils and their Function as Trojan Horses to the Placenta

ZIKV is a 11Kb positive stranded flavivirus transmitted by infected Aedes aegypti and by sexual intercourse. After a short period of viremia of 5-7 days, the virus is cleared, and infection resolved in 80% of individuals. However, around 27% of the fetuses from pregnant infected mothers may develop several fetal brain and ocular pathology. Here we show that murine and peripheral blood human neutrophils support ZIKV infection and replication both in vitro and in vivo, which may correlate to the facilitation of vertical transmission. ZIKV did not interfere with cell viability, neither induced ROS production nor the release of NETs by infected neutrophils. Also, ZIKV infection of neutrophils did not trigger a pro-inflammatory profile, as evidenced by qPCR and proteomic analysis. Interestingly, ZIKV-infected neutrophils were isolated from the placenta were highly infected. The transference of in vitro ZIKV-infected neutrophils to pregnant female mice favored the transference of viral particles to the fetus. Conversely, neutrophil depletion with monoclonal antibodies reduced fetal viral loads whereas the treatment with recombinant G-CSF has the opposite effect. In summary, although it has already been shown that circulating monocytes harbor ZIKV, to our knowledge, this is the first report demonstrating the role of neutrophils during ZIKV infection, and most important, that it may act as a trojan horse to placental tissue directly impacting the pathogenesis of congenital syndrome.

immunology↗

bioRxiv2020

Metabolic cooperation among commensal bacteria supports Drosophila juvenile growth under nutritional stress

The gut microbiota shapes animal growth trajectory in stressful nutritional environments, but the molecular mechanisms behind such physiological benefits remain poorly understood. The gut microbiota is mostly composed of bacteria, which construct metabolic networks among themselves and with the host. Until now, how the metabolic activities of the microbiota contribute to host juvenile growth remains unknown. Here, using Drosophila as a host model, we report that two of its major bacterial partners, Lactobacillus plantarum and Acetobacter pomorum engage in a beneficial metabolic dialogue that boosts host juvenile growth despite nutritional stress. We pinpoint that lactate, produced by L. plantarum, is utilized by A. pomorum as an additional carbon source, and A. pomorum provides essential amino-acids and vitamins to L. plantarum. Such bacterial cross-feeding provisions a set of anabolic metabolites to the host, which may foster host systemic growth despite poor nutrition. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=165 SRC="FIGDIR/small/119370v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@1923739org.highwire.dtl.DTLVardef@679795org.highwire.dtl.DTLVardef@110cbecorg.highwire.dtl.DTLVardef@1bc0804_HPS_FORMAT_FIGEXP M_FIG C_FIG HIGHLIGHTSO_LIL. plantarum feeds lactate to A. pomorum C_LIO_LIA. pomorum supplies essential amino acids and vitamins to L. plantarum C_LIO_LIMicrobiota metabolic dialogue boosts Drosophilas larval growth C_LIO_LILactate utilization by Acetobacter releases anabolic metabolites to larvae C_LI

microbiology↗

bioRxiv2019

Commensal bacteria differentially shape the nutritional requirements of Drosophila during juvenile growth

The interplay between nutrition and the microbial communities colonizing the gastro-intestinal tract (i.e. gut microbiota) determines juvenile growth trajectory. Nutritional deficiencies trigger developmental delays, and an immature gut microbiota is a hallmark of pathologies related to childhood undernutrition. However, how commensal bacteria modulate the impact of nutrition on juvenile growth remains elusive. Here, using gnotobiotic Drosophila melanogaster larvae independently associated with two model commensal bacterial strains, Acetobacter pomorumWJL (ApWJL) and Lactobacillus plantarumNC8 (LpNC8), we performed a large-scale, systematic nutritional screen based on larval growth in 40 different and precisely controlled nutritional environments. We combined these results with genome-based metabolic network reconstruction to define the biosynthetic capacities of Drosophila germ-free (GF) larvae and its two commensal bacteria. We first established that ApWJL and LpNC8 differentially fulfills the nutritional requirements of the ex-GF larvae and parsed such difference down to individual amino acids, vitamins, other micronutrients and trace metals. We found that Drosophila commensal bacteria not only fortify the hosts diet with essential nutrients but, in specific instances, functionally compensate for host auxotrophies, by either providing a metabolic intermediate or nutrient derivative to the host or by uptaking, concentrating and sparing contaminant traces of micronutrients. Our systematic work reveals that, beyond the molecular dialogue engaged between the host and its commensal partners, Drosophila and its facultative bacterial partners establish an integrated nutritional network relying on nutrients sparing and utilization.

physiology↗

bioRxiv2018

A novel role of VisP and Wzz system during O-antigen assembly in Salmonella Typhimurium pathogenesis

Salmonella enterica serovars are associated with diarrhea and gastroenteritis and are a helpful model for understanding host-pathogen mechanisms. Salmonella Typhimurium regulates the distribution of O-antigen (OAg) and presents a trimodal distribution based on Wzy polymerase, WzzST (long chain length OAg, L-OAg) and WzzfepE (very long chain length OAg, VL-OAg) co-polymerases; however, several mechanisms regulating this process remain unclear. Here, we report that LPS modifications modulate the infectious process and that OAg chain length determination plays an essential role during infection. An increase in VL-OAg is dependent on Wzy polymerase, which is promoted by a growth condition resembling the environment of Salmonella-containing vacuoles (SCVs). The virulence and stress-related periplasmic protein (VisP) participates in OAg synthesis, as {Delta}visP presents a semirough OAg phenotype. The {Delta}visP mutant has greatly decreased motility and J774 macrophage survival in a colitis model of infection. Interestingly, the phenotype is restored after mutation of the wzzST or wzzfepE gene in a {Delta}visP background. Loss of both the visP and wzzST genes promotes an imbalance in flagellin secretion. L-OAg may function as a shield against host immune systems in the beginning of an infectious process, and VL-OAg protects bacteria during SCV maturation and facilitates intramacrophage replication. Taken together, these data highlight the roles of OAg length in generating phenotypes during S. Typhimurium pathogenesis and show the periplasmic protein VisP as a novel protein in the OAg biosynthesis pathway.\n\nAuthor summarySalmonella modifies its LPS, specifically the O-antigen length, to adapt itself to distinct intestinal environments. These LPS modifications may provide a way for this bacterium to avoid complement activation in the intestinal lumen, improving Salmonella pathogenesis. This process is essential for a successful infection, and our investigation into these specific details regarding LPS in this foodborne pathogen will elucidate different aspects of the host-pathogen association.

microbiology↗