Percorrer por autor "Fernandes, Alexandra R."
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- Assessing in vivo and in vitro biofilm development by Streptococcus dysgalactiae subsp. dysgalactiae using a murine model of catheter-associated biofilm and human keratinocyte cellPublication . Alves-Barroco, Cinthia; Botelho, Ana Maria Nunes; Américo, Marco Antonio; Fracalanzza, Sérgio Eduardo Longo; Matos, António P. Alves de; Guimaraes, Márcia Aparecida; Ferreira-Carvalho, Bernadete Teixeira; Figueiredo, Agnes Marie Sá; Fernandes, Alexandra R.Streptococcus dysgalactiae subsp. dysgalactiae (SDSD) is an important agent of bovine mastitis. This infection causes an inflammatory reaction in udder tissue, being the most important disease-causing significant impact on the dairy industry. Therefore, it leads to an increase in dairy farming to meet commercial demands. As a result, there is a major impact on both the dairy industry and the environment including global warming. Recurrent mastitis is often attributed to the development of bacterial biofilms, which promote survival of sessile cells in hostile environments, and resistance to the immune system defense and antimicrobial therapy. Recently, we described the in vitro biofilm development on abiotic surfaces by bovine SDSD. In that work we integrated microbiology, imaging, and computational methods to evaluate the biofilm production capability of SDSD isolates on abiotic surfaces. Additionally, we reported that bovine SDSD can adhere and internalize human cells, including human epidermal keratinocyte (HEK) cells. We showed that the adherence and internalization rates of bovine SDSD isolates in HEK cells are higher than those of a SDSD DB49998-05 isolated from humans. In vivo, bovine SDSD can cause invasive infections leading to zebrafish morbidity and mortality. In the present work, we investigated for the first time the capability of bovine SDSD to develop biofilm in vivo using a murine animal model and ex-vivo on human HEK cells. Bovine SDSD isolates were selected based on their ability to form weak, moderate, or strong biofilms on glass surfaces. Our results showed that SDSD isolates displayed an increased ability to form biofilms on the surface of catheters implanted in mice when compared to in vitro biofilm formation on abiotic surface. A greater ability to form biofilm in vitro after animal passage was observed for the VSD45 isolate, but not for the other isolates tested. Besides that, in vitro scanning electron microscopy demonstrated that SDSD biofilm development was visible after 4 hours of SDSD adhesion to HEK cells. Cell viability tests showed an important reduction in the number of HEK cells after the formation of SDSD biofilms. In this study, the expression of genes encoding BrpA-like (biofilm regulatory protein), FbpA (fibronectin-binding protein A), HtrA (serine protease), and SagA (streptolysin S precursor) was higher for biofilm grown in vivo than in vitro, suggesting a potential role for these virulence determinants in the biofilm-development, host colonization, and SDSD infections. Taken together, these results demonstrate that SDSD can develop biofilms in vivo and on the surface of HEK cells causing important cellular damages. As SDSD infections are considered zoonotic diseases, our data contribute to a better understanding of the role of biofilm accumulation during SDSD colonization and pathogenesis not only in bovine mastitis, but they also shed some lights on the mechanisms of prosthesis-associated infection and cellulitis caused by SDSD in humans, as well.
- Genetic predisposition for aggressive behaviour related with dopamine and serotonin pathways : an overviewPublication . Paulino, Cathy; Fernandes, Alexandra R.; Baptista, Pedro V.; Soeiro, Cristina; Grosso, Ana Rita; Quintas, Alexandre
- Shared inflammatory genetic susceptibility underlying spontaneous preterm birth and periodontitis : a case–control studyPublication . Couceiro, Joana; Família, Carlos; Brito, José; Mendes, José João; Baptista, Pedro V.; Fernandes, Alexandra R.; Quintas, AlexandreBackground: Preterm birth (PTB) remains the leading cause of neonatal morbidity and mortality worldwide, with approximately two-thirds of cases occurring spontaneously (SPTB), but the etiology is still poorly understood. Chronic inflammatory diseases, such as periodontitis (PD), have been considered SPTB risk factors. However, we hypothesized that SPTB may instead represent a clinical manifestation of a broader genetic predisposition to dysregulated inflammation. Using PD as a model of chronic inflammation, we examined shared genetic susceptibility. Methods: In a case–control study (N = 126 Portuguese postpartum women), we screened 56 SNPs in 36 inflammation-related genes. Four functionally plausible variants (IL1RN rs4251961, TLR1 rs5743618, IL6 rs2069827, and IL6R rs4845617) were selected for detailed regression, adjusting for gestational age, floss usage, and an SPTBxPD interaction term. Results: IL1RN rs4251961 was recessively associated with SPTB risk, consistent with reduced IL-1RA expression linked to this variant. IL6R rs4845617 showed a modest protective effect. TLR1 rs5743618 exhibited the strongest association with the composite “inflammation” phenotype under multiple models, with CC homozygotes showing four-fold increased odds, independent of SPTB/PD co-occurrence. Conclusions: This study provides original evidence that shared genetic variants in inflammatory pathways—particularly TLR1 rs5743618—may underlie susceptibility to SPTB and PD. Our findings suggest a paradigm shift, viewing SPTB as a possible outcome of systemic inflammatory dysregulation rather than merely a consequence of comorbid inflammatory conditions. Future studies should validate this marker in larger cohorts.
- Specific antiproliferative properties of proteinaceous toxin secretions from the marine annelid Eulalia sp. onto ovarian cancer cellsPublication . Rodrigo, Ana P.; Mendes, Vera M.; Manadas, Bruno; Grosso, Ana R.; Matos, António P. Alves de; Baptista, Pedro V.; Costa, Pero M.; Fernandes, Alexandra R.As Yondelis joins the ranks of approved anti-cancer drugs, the benefit from exploring the oceans’ biodiversity becomes clear. From marine toxins, relevant bioproducts can be obtained due to their potential to interfere with specific pathways. We explored the cytotoxicity of toxin-bearing secretions of the polychaete Eulalia onto a battery of normal and cancer human cell lines and discovered that the cocktail of proteins is more toxic towards an ovarian cancer cell line (A2780). The secretions’ main proteins were identified by proteomics and transcriptomics: 14-3-3 protein, Hsp70, Rab3, Arylsulfatase B and serine protease, the latter two being known toxins. This mixture of toxins induces cell-cycle arrest at G2/M phase after 3h exposure in A2780 cells and extrinsic programmed cell death. These findings indicate that partial re-activation of the G2/M checkpoint, which is inactivated in many cancer cells, can be partly reversed by the toxic mixture. Protein–protein interaction networks partake in two cytotoxic effects: cell-cycle arrest with a link to RAB3C and RAF1; and lytic activity of arylsulfatases. The discovery of both mechanisms indicates that venomous mixtures may affect proliferating cells in a specific manner, highlighting the cocktails’ potential in the fine-tuning of anti-cancer therapeutics targeting cell cycle and protein homeostasis.
- The genetic susceptibility linking preterm birth and periodontal disease : a reviewPublication . Couceiro, Joana; Grosso, Ana Rita; Baptista, Pedro V.; Mendes, José João; Fernandes, Alexandra R.; Quintas, Alexandre