Research Institute for Medicines

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Investigation of the genotoxicity of digested titanium dioxide nanomaterials in human intestinal cells

Publication . Vieira, Adriana; Rolo, Dora; Vital, Nádia; Martins, Carla; Assunção, Ricardo; Alvito, Paula; Gonçalves, Lídia; Bettencourt, Ana F.; Silva, Maria João; Louro, Henriqueta

About Investigation of the genotoxicity of digested titanium dioxide nanomaterials in human intestinal cells

2022-03-22Conference object

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Titanium Dioxide Nanoparticles molecular effects: Internalization in the Human Intestinal Epithelium

Publication . Rolo, Dora; Pereira, Joana FS; Matos, Paulo; Gonçalves, Lídia; Bettencourt, Ana Francisca; Jordan, Peter; Silva, Maria João; Louro, Henriqueta

The use of titanium dioxide nanoparticles (TiO2-NPs) as food additive and in food packaging demands a thorough assessment of their potential risk for human health, specifically with regard to gastrointestinal tract. Using intestinal cells, we analyzed the mechanisms by which digested TiO2-NPs (NM-102, NM-103 and NM-105, JRC repository) translocate through the intestinal epithelium layer, as compared to non-digested particles. Human digestion of TiO2-NPs was simulated using the INFOGEST in vitro harmonized digestion method. Caco-2 cells were grown as polarized cell monolayer for exposure and differentiation was evaluated by TEER. The translocation of TiO2-NPs, tagged with alizarin red, through the cell barrier was analysed by confocal microscopy, using colocalization with antibodies against specific endosomal compartments. The internalization of the TiO2-NPs was confirmed for the three TiO2-NPs tested, both before and after digestion simulation. The smallest TiO2-NPs were internalized into EEA1-positive early- endosomes and accumulated in late endosomes (Rab7), with only a small fraction following the degradative pathway to the lysosome (LAMP1). The data suggested that at least part of the TiO2-NPs could be redirected to the secretory pathway. Consistently, fluorescence passing from the apical to the basolateral chamber was observed, without disruption of the intestinal barrier function. The changes in cell function or signal transduction pathways are being studied and possible consequences to human gastrointestinal tract arediscussed. We thank the support from P. Alvito, C. Martins and R. Assunção (INSA,Lisbon, Portugal).

2021-09-23Conference object

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The 2-hydroxy-nevirapine metabolite as a candidate for boosting apolipoprotein A1 and for modulating anti-HDL antibodies

Publication . Marinho, Aline T.; Batuca, Joana R.; Miranda, Joana P.; Caixas, Umbelina; Dias, Clara G.; Branco, Teresa; Soto, Karina; Pinheiro, Pedro; Bourbon, Mafalda; Marques, M. Matilde; Antunes, Alexandra M.; Monteiro, Emília C.; Pereira, Sofia A.

The antiretroviral nevirapine (NVP) is associated to a reduction of atherosclerotic lesions and increases in high-density lipoprotein (HDL)-cholesterol. Despite being a hepatotoxic drug, which forbids its re-purposing to other therapeutic areas, not all NVP metabolites have the same potential to induce toxicity. Our aim was to investigate the effects of NVP and its metabolites in an exploratory study, towards the identification of a candidate to boost HDL. A pilot prospective (n = 11) and a cross-sectional (n = 332) clinical study were performed with the following endpoints: HDL-cholesterol and apolipoprotein A1 (ApoA1) levels, anti-HDL and anti-ApoA1 antibodies titers, paraoxonase, arylesterase and lactonase activities of paraoxonase-1, and NVP's metabolite profile. NVP treatment increased HDL-cholesterol, ApoA1 and paraoxonase-1 activities, and lowered anti-HDL and anti-ApoA1 titers. In the prospective study, the temporal modulation induced by NVP was different for each HDL-related endpoint. The first observation was a decrease in the anti-HDL antibodies titers. In the cross-sectional study, the lower titers of anti-HDL antibodies were associated to the proportion of 2-hydroxy-NVP (p = 0.03). In vitro models of hepatocytes were employed to clarify the individual contribution of NVP's metabolites for ApoA1 modulation. Long-term incubations of NVP and 2-hydroxy-NVP in the metabolically competent 3D model caused an increase in ApoA1 reaching 43 % (p < 0.05) and 86 % (p < 0.001), respectively. These results support the contribution of drug biotransformation for NVP-induced HDL modulation, highlighting the role of 2-hydroxy-NVP as ApoA1 booster and its association to lower anti-HDL titers. This biotransformation-guided approach allowed us to identify a non-toxic NVP metabolite as a candidate for targeting HDL.

2021-03-16Journal article

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Using genomics to understand the origin and dispersion of multidrug and extensively drug resistant tuberculosis in Portugal

Publication . Perdigão, João; Gomes, Pedro; Miranda, Anabela; Maltez, Fernando; Machado, Diana; Silva, Carla; Phelan, Jody E.; Brum, Laura; Campino, Susana; Couto, Isabel; Viveiros, Miguel; Clark, Taane G.; Portugal, Isabel

Portugal is a low incidence country for tuberculosis (TB) disease. Now figuring among TB low incidence countries, it has since the 1990s reported multidrug resistant and extensively drug resistant (XDR) TB cases, driven predominantly by two strain-types: Lisboa3 and Q1. This study describes the largest characterization of the evolutionary trajectory of M/XDR-TB strains in Portugal, spanning a time-period of two decades. By combining whole-genome sequencing and phenotypic susceptibility data for 207 isolates, we report the geospatial patterns of drug resistant TB, particularly the dispersion of Lisboa3 and Q1 clades, which underly 64.2% and 94.0% of all MDR-TB and XDR-TB isolates, respectively. Genomic-based similarity and a phylogenetic analysis revealed multiple clusters (n = 16) reflecting ongoing and uncontrolled recent transmission of M/XDR-TB, predominantly associated with the Lisboa3 and Q1 clades. These clades are now thought to be evolving in a polycentric mode across multiple geographical districts. The inferred evolutionary history is compatible with MDR- and XDR-TB originating in Portugal in the 70's and 80's, respectively, but with subsequent multiple emergence events of MDR and XDR-TB particularly involving the Lisboa3 clade. A SNP barcode was defined for Lisboa3 and Q1 and comparison with a phylogeny of global strain-types (n = 28 385) revealed the presence of Lisboa3 and Q1 strains in Europe, South America and Africa. In summary, Portugal displays an unusual and unique epidemiological setting shaped by >40 years of uncontrolled circulation of two main phylogenetic clades, leading to a sympatric evolutionary trajectory towards XDR-TB with the potential for global reach.

2020-02-13Journal article

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