Biology subjects

Torres, A. G.

Publications and source records attributed to Torres, A. G..

6 recordsLinked to original sources

bioRxiv2025

Endogenous antimicrobial peptides in human colostrum: a peptidomics study by liquid-chromatography high-resolution mass-spectrometry (LC-HRMS) and bioinformatics

Human colostrum is recognized as a source of bioactive compounds that impact on neonatal development, such as antimicrobial peptides. Antimicrobial peptides (AMPs) present some common characteristics, as they are relatively small (<10 kDa), most of them are positively charged and possess -helical regions. These molecules can protect the newborn against infectious agents such as bacteria, fungi, and viruses. Using an MS- based proteomic approach combined with the application of bioinformatic tools, 29 peptide sequences from human colostrum were annotated in human colostrum. These peptides are potentially antifungal and were enriched in glutamic acid (E), phenylalanine (F), lysine (K) and tryptophan (W) residues. Among the precursor proteins, two have a known 3D structure and their fragments are located in the protein core. In addition, in silico analyses revealed that AMPs containing regions of -helix and random structures, and high aliphatic index (mean of 85.29) tend to be thermostable. In this work with human colostrum, previously unreported peptides with potential antimicrobial activity were annotated and structurally characterized via bioinformatic tools.

biochemistry↗

bioRxiv2024

Metabolic imprint of an intracellular pathogen drives histone hypermethylation and tunes the host transcriptional response to infection

Chlamydia trachomatis, an intracellular bacterium, highjacks metabolites from the host cell for its own proliferation. We provide evidence of global hypermethylation of the host proteome, including histones, during the late stages of infection. Single cell analyses revealed co-occurrence of several methylated residues on histones. Histone hypermethylation correlated with bacterial load and was prevented by antibiotic treatment. Mapping of trimethylation of histone 3 at residues K4 and K9 revealed a broad distribution throughout the chromatin. Nuclear fractions of infected cells exhibited a four-fold decrease of demethylase activity towards H3K4me3 and a two-fold increase in succinate concentration, a competitive inhibitor for the demethylase co-factor -ketoglutarate. Supplementation of the culture medium with dimethyl-ketoglutarate (DMKG) or with iron, a second co-factor of histone lysine demethylases, reduced histone hypermethylation. DMKG supplementation modified the transcription of about one third of the infection-responsive genes, indicating that histone hypermethylation contributes to modulating the transcriptional response of the host to infection. Finally, chemical inhibition of histone demethylases in a mouse model of infection showed a moderate benefit regarding the outcome of infection. Overall, our data show that the metabolic pressure exerted by a pathogen with an intracellular lifestyle drives epigenetic changes in infected cells.

cell biology↗

bioRxiv2024

Contribution of the Type 6 Secretion System to Apoptosis and Macrophage Polarization During Burkholderia pseudomallei Infection

Burkholderia pseudomallei (Bpm) is the causative agent of the disease melioidosis. As a facultative intracellular pathogen, Bpm has a complex lifestyle that culminates in cell-to-cell fusion and multinucleated giant cells (MNGCs) formation. The virulence factor responsible for MNGC formation is the type 6 secretion system (T6SS), a contractile nanomachine. MNGC formation is a cell-to-cell spread strategy that allows the bacteria to avoid the extracellular immune system and our previous data highlighted cell death, apoptosis, and inflammation as pathways significantly impacted by T6SS activity. Thusly, we investigated how the T6SS influences these phenotypes within the macrophage and pulmonary models of infection. Here we report that the T6SS is responsible for exacerbating apoptotic cell death during infection in both macrophages and the lungs of infected mice. We also demonstrate that although the T6SS does not influence differential macrophage polarization, the M2 polarization observed is potentially beneficial for Bpm pathogenesis and replication. Finally, we show that the T6SS contributes to the severity of inflammatory nodule formation in the lungs, which might be potentially connected to the amount of apoptosis that is triggered by the bacteria.

microbiology↗

bioRxiv2024

Decoration of Burkholderia Hcp1 protein to virus-like particles as a vaccine delivery platform.

Virus-like particles (VLPs) are protein-based nanoparticles frequently used as carrier in conjugate vaccine platforms. VLPs have been used to display foreign antigens for vaccination and to deliver immunotherapeutic against diseases. Hemolysin-coregulated proteins 1 (Hcp1) is a protein component of the Burkholderia type 6 secretion system which participates in intracellular invasion and dissemination. This protein has been reported as a protective antigen and is used in multiple vaccine candidates with various platforms against melioidosis, a severe infectious disease caused by the intracellular pathogen B. pseudomallei. In this study, we used P22 VLPs as a surface platform for decoration with Hcp1 using chemical conjugation. C57BL/6 mice were intranasally immunized with three doses of either PBS, VLPs or conjugated Hcp1-VLPs. Immunization with Hcp1-VLPs formulation induced Hcp1-specific-IgG, IgG1, IgG2c and IgA antibody responses. Furthermore, the serum from Hcp1-VLPs immunized mice enhanced the bacterial uptake and opsonophagocytosis by macrophages in the presence of complement. This study demonstrated an alternative strategy to develop a VLPs-based vaccine platform against Burkholderia species.

microbiology↗

bioRxiv2023

Burkholderia pseudomallei BicA protein promotes pathogenicity in macrophages by regulating Invasion, Intracellular Survival, and Virulence.

Burkholderia pseudomallei (Bpm) is the causative agent of melioidosis disease. Bpm is a facultative intracellular pathogen with a complex lifecycle inside host cells. Pathogenic success depends on a variety of virulence factors with one of the most critical being the type 6 secretion system (T6SS). Bpm uses the T6SS to move into neighboring cells, resulting in multinucleated giant cells (MNGCs) formation, a strategy used to disseminate from cell-to-cell. Our prior study using a dual RNA-seq analysis to dissect T6SS-mediated virulence on intestinal epithelial cells identified BicA as a factor upregulated in a T6SS mutant (1). BicA regulates both type 3 secretion system (T3SS) and T6SSs; however, the extent of its involvement during disease progression is unclear. To fully dissect the role of BicA during systemic infection, we used two macrophage cell lines paired with a pulmonary in vivo challenge murine model. We found that {Delta}bicA has a distinct intracellular replication defect in both immortalized and primary macrophages that begins as early as 1 h post-infection. This intracellular defect is linked with the lack of cell-to-cell dissemination and MNGC formation, as well as a defect on T3SS expression. The in vitro phenotype translated in vivo as {Delta}bicA was attenuated in a pulmonary model of infection; demonstrating a distinct macrophage activation profile and lack of pathological features present in the wild type. Overall, these results highlight the role of BicA in regulating intracellular virulence and demonstrate that specific regulation of secretion systems has a significant effect on host response and Bpm pathogenesis. ImportanceMelioidosis is an understudied tropical disease that still results in [~]50% fatalities from those infected patients. It is caused by the Gram-negative bacillus Burkholderia pseudomallei (Bpm). Bpm is an intracellular pathogen that disseminates from the infected cell to target organs, causing disseminated disease. Regulation of secretion systems involved in entry and cell-to-cell spread is poorly understood. In this work, we characterize the role of BicA as a regulator of secretion systems during infection of macrophages in vitro and in vivo. Understanding how these virulence factors are controlled will help us determine their influence on the host cells and define the macrophage responses associated with bacterial clearance.

microbiology↗

bioRxiv2022

Dual RNA-seq reveals a type 6 secretion system-dependent blockage of TNF-α signaling and BicA as a Burkholderia pseudomallei virulence factor important during gastrointestinal infection

Melioidosis is a disease caused by the Gram-negative bacillus Burkholderia pseudomallei (Bpm), commonly found in soil and water of endemic areas. Naturally acquired human melioidosis infections can result from either exposure through percutaneous inoculation, inhalation, or ingestion of soil-contaminated food or water. Our prior studies recognized Bpm as an effective enteric pathogen, capable of establishing acute or chronic gastrointestinal infections following oral inoculation. However, the specific mechanisms and virulence factors involved in the pathogenesis of Bpm during intestinal infection are unknown. In our current study, we standardized an in vitro intestinal infection model using primary intestinal epithelial cells (IECs) and demonstrated that Bpm requires a functional T6SS for full virulence. Further, we performed dual RNA-seq analysis on Bpm-infected IECs to evaluate differentially expressed host and bacterial genes in the presence or absence of a T6SS. Our results showed a dysregulation in the TNF- signaling via NF-{kappa}B pathway in the absence of the T6SS, with some of the genes involved in inflammatory processes and cell death also affected. Analysis of the bacterial transcriptome identified virulence factors and regulatory proteins playing a role during infection, with association to the T6SS. By using a Bpm transposon mutant library and isogenic mutants, we showed that deletion of the bicA gene, encoding a putative T3SS/T6SS regulator, ablated intracellular survival and plaque formation by Bpm and impacted survival and virulence when using murine models of acute and chronic gastrointestinal infection. Overall, these results highlight the importance of the type 6 secretion system in the gastrointestinal pathogenesis of Bpm.

microbiology↗