Biology subjects

Leitao, R.

Publications and source records attributed to Leitao, R..

5 recordsLinked to original sources

bioRxiv2026

A Direct DNA Extraction Workflow for Metabarcoding Fungal Bioaerosols from Adhesive Samplers

Monitoring fungal bioaerosols is essential for understanding their impacts on human health and crop productivity. However, current monitoring approaches rely on culture-dependent techniques, which underestimate the diversity of fungal exposures. Adhesive-coated films can effectively capture airborne particles but have been regarded as unsuitable for DNA downstream analysis, owing to the lack of standardised DNA extraction methods for the adhesive capture surface. Here, we present an optimised DNA extraction protocol for adhesive film, which we developed and validated to enable direct and culture-independent ITS2-based metabarcoding of fungal bioaerosols collected on a 96 well plate sealing film ( Sticky sampler). This validated approach was applied to field samples collected from four agricultural farms and from a domestic garden to evaluate seasonal and spatial changes in fungal bioaerosols. Our analysis uncovered pronounced site-specific contrasts linked to geography and land management, as well as clear seasonal shifts in garden fungal communities. This study demonstrates that adhesive samplers, combined with optimised DNA extraction, provide a practical and inexpensive tool for fungal bioaerosol research by resolving ecologically meaningful spatiotemporal dynamics of airborne fungi. This protocol opens new opportunities for highly scalable surveillance of environmental bioaerosols.

microbiology↗

bioRxiv2024

Genomic epidemiology of emerging terbinafine-resistant Trichophyton indotineae

Dermatophyte skin infections affect around a quarter of the worlds population and are a growing public health concern due to increasing incidence of novel species causing severe infections that are resistant to antifungal treatments. Trichophyton species cause the greatest burden of dermatophytosis worldwide, with the T. mentagrophytes species complex being particularly associated with the emergence of new aggressive infections. One emerging species, T. indotineae (originally T. mentagrophytes genotype VIII) is notable for the extensive nature of the often inflammatory infection, its clinical resistance to terbinafine antifungal treatment, and its rapid global spread. To better understand the epidemiology of this disease, we sourced isolates from severe cases of dermatophytosis in the United Kingdom, Ireland, France, Canada and India for the period 2018-2023, including the type strain from Japan. We used whole-genome sequencing to confirm 90 isolates were T. indotineae, and antifungal susceptibility testing indicated that over half of these (62%) were resistant to terbinafine (MIC [≥]1 mg/L). Pairwise genetic distances showed very high identity with only 147 (1-414) SNPs separating isolates that were nested within a monophyletic phylogeny, supporting a single evolutionary origin of T. indotineae. That no clear geographic clustering of isolates was observed confirms the rapid transcontinental spread of T. indotineae from its likely centre of diversity in Asia. Genome-wide analyses identified multiple non-synonymous SNPs in SQLE (ERG1), the squalene epoxidase target of terbinafine, that were associated with terbinafine in vitro resistance [≥]1 mg/L. However, five isolates exhibited high MIC values without SQLE mutations, suggesting the presence of alternative resistance mechanisms. Our findings highlight the importance of better genomic surveillance to understand and manage this severe and rapidly emerging terbinafine-resistant dermatophyte.

genomics↗

bioRxiv2024

Deciphering the impact of cancer cells secretome and its derived-peptide VGF on breast cancer brain metastasis

Brain metastases (BM) are one of the most serious clinical problems in breast cancer (BC) progression, associated with lower survival rates and a lack of effective therapies. Thus, to dissect the early stages of the brain metastatic process, we have searched for a brain-tropic metastatic signature on BC cells secretome, as a promising source for the discovery of new biomarkers involved in brain metastatic progression. Therefore, six specifically deregulated peptides were found to be enriched in the secretome of brain organotropic BC cells. Importantly, these secretomes caused significant blood-brain barrier (BBB) disruption, as well as microglial activation, in vitro and in vivo. We identified the VGF nerve growth factor inducible as a brain-specific peptide, promoting BBB dysfunction similar to the secretome of brain organotropic BC cells. Concerning microglial activation, a slight increase was also observed upon VGF treatment. In a series of human breast tumors, VGF was found to be expressed in both cancer cells and in the adjacent stroma. VGF-positive tumors showed a significant worse prognosis and were associated with HER2 overexpression and triple-negative molecular signatures. Finally, in a cohort including primary breast tumors and their corresponding metastatic locations to the lung, bone, and brain, we found that VGF significantly correlates with the brain metastatic site. In conclusion, we found a specific BC brain metastatic signature, where VGF was identified as a key mediator in this process. Importantly, its expression was associated with poor prognosis for BC patients, probably due to its associated increased risk of developing BM.

cancer biology↗

bioRxiv2023

Determining the microbial species content in tissue from Alzheimer's and Parkinson's Disease patients

The aetiology of Alzheimers disease (AD) and Parkinsons Disease (PD) are unknown and tend to manifest at a later stage in life; even though these diseases have different pathogenic mechanisms, they are both characterized by neuroinflammation in the brain. Links between bacterial and viral infection and AD/PD has been suggested in several studies, however, few have attempted to establish a link between fungal infection and AD/PD. In this study we develop and describe a nanopore-based sequencing approach to characterise the presence or absence of fungi in both human brain tissue and cerebrospinal fluid (CSF). This approach detects fungal DNA in human brain and CSF samples even at low levels, whereas our quantitative polymerase chain reaction (qPCR) assay (FungiQuant) was unable to detect fungal DNA in the same samples. Comparison against kit-controls showed ubiquitous low-level fungal contamination that we observed in healthy human brains and CSF as well AD/PD brains and CSF. We use this technique to demonstrate the presence of fungal DNA in healthy human brains as well as AD/PD brains, with Alternaria spp., Colletotrichum graminicola, and Filobasidium floriforme as the most prominent species. In addition, antibiotic resistant Pseudomonas spp. was identified within the brain of an AD patient. Our method will be broadly applicable to investigating potential links between microbial infection and AD/PD.

microbiology↗

bioRxiv2022

Loss of the intracellular enzyme QPCTL limits chemokine function and reshapes myeloid infiltration to augment tumor immunity

Tumor-associated macrophages are composed of distinct populations arising from monocytes or tissue macrophages, with a poorly understood link to disease pathogenesis. Here, we demonstrate that mouse monocyte migration was supported by glutaminyl-peptide cyclotransferase-like (QPCTL), an enzyme that mediates N-terminal modification of several subtrates, including the monocyte-chemoattractants CCL2 and CCL7, protecting them from proteolytic inactivation. Knockout of Qpctl disrupted monocyte homeostasis, attenuated tumor growth and reshaped myeloid cell infiltration, with loss of monocyte-derived populations with immunosuppressive and pro-angiogenic profiles. Antibody blockade of the receptor CSF1R, which more broadly eliminates tissue macrophages, reversed tumor growth inhibition in Qpctl-/- mice, and prevented lymphocyte infiltration. Modulation of QPCTL synergized with anti-PD-L1 to expand CD8+ T cells and limit tumor growth. QPCTL inhibition constitutes an effective approach for myeloid cell-targeted cancer immunotherapy.

immunology↗