Pedro Rodrigues

Institute for Molecular and Cell Biology, Oporto, Porto, Portugal

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Publications (30)94.26 Total impact

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    ABSTRACT: Mycobacterium avium causes respiratory disease in susceptible individuals, as well as disseminated infections in immunocompromised hosts, being an important cause of morbidity and mortality among these populations. Current therapies consist of a combination of antibiotics taken for at least six months, with no more than 60% overall clinical success. Furthermore, mycobacterial antibiotic resistance is increasing worldwide, urging the need to develop novel classes of antimicrobial drugs. One potential and interesting alternative strategy is the use of antimicrobial peptides (AMP). These are present in almost all living organisms as part of their immune system, acting as a first barrier against invading pathogens. In this context, we investigated the effect of several lactoferrin-derived AMP against M. avium. Short peptide sequences from both human and bovine lactoferricins, namely hLFcin1-11 and LFcin17-30, as well as variants obtained by specific amino acid substitutions, were evaluated. All tested peptides significantly inhibited the axenic growth of M. avium, the bovine peptides being more active than the human. Arginine residues were found to be crucial for the display of antimycobacterial activity, whereas the all-D amino acid analogue of the bovine sequence displayed the highest mycobactericidal activity. These findings reveal the promising potential of lactoferricins against mycobacteria, thus opening the way for further research on their development and use as a new weapon against mycobacterial infections.
    Antimicrobial Agents and Chemotherapy 04/2014; · 4.57 Impact Factor
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    ABSTRACT: The locomotory appendages of vertebrates have undergone significant changes during evolution, which likely promoted a wide range of adaptive strategies. These appendages first evolved as unpaired finfolds in the dorsal midline of early chordates, more than 500 million years ago. Later on, during vertebrates' radiation, two sets of locomotory appendages emerged, developing from both sides of the latero-ventral body wall. The morphology of these paired fins in fishes at different phylogenetic positions suggests an evolutionary tendency for increasing elaboration of the endoskeleton and concomitant reduction of the distal dermoskeleton. This evolutionary process culminated with the origin of limbs in the lineages leading to tetrapods. The developmental programs responsible for the evolution of vertebrate appendages have been a major topic for evolutionary developmental biology recently. Gene expression comparisons performed in chordates explored how these mechanisms were transferred from a midline to latero-ventral position. On another front, gene function assays have begun to test classical hypotheses concerning the transition from fish fins to tetrapod limbs. In this review, we highlight these recent findings on the evolution of vertebrate fin development. First, we discuss new perspectives on the transition from midline to paired appendages focus on (i) origin and molecular regionalization of the lateral plate mesoderm and (ii) novel ectodermic competency zones for fin induction. Next, we review recent work exploring how tetrapod limbs evolved from fish fins, considering (i) molecular and structural changes in the distal ectoderm of fins and (ii) modulation of 5'HoxD transcription during fin endoskeleton development. J. Exp. Zool. (Mol. Dev. Evol.) 9999B: XX-XX, 2014. © 2014 Wiley Periodicals, Inc.
    Journal of Experimental Zoology Part B Molecular and Developmental Evolution 02/2014; · 2.12 Impact Factor
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    ABSTRACT: Important for both host and pathogen survivals, iron is a key factor in determining the outcome of an infectious process. Iron with-holding, including sequestration inside tissue macrophages, is considered an important strategy to fight infection. However, for intra-macrophagic pathogens, such as Mycobacterium avium, host defence may depend on intracellular iron sequestration mechanisms. Ferritin, the major intracellular iron storage protein, plays a critical role in this process. In the current study, we studied ferritin expression in mouse bone marrow-derived macrophages upon infection with M. avium. We found that H-ferritin is selectively increased in infected macrophages, through an up-regulation of gene transcription. This increase was mediated by the engagement of Toll like receptor-2, and was independent of TNF-alpha or nitric oxide production. The formation of H-rich ferritin proteins and the consequent iron sequestration may be an important part of the panoply of antimicrobial mechanisms of macrophages.
    PLoS ONE 12/2013; 8(12):e82874. · 3.53 Impact Factor
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    ABSTRACT: The liver, being the major site of iron storage, is particularly exposed to the toxic effects of iron. Transcription factor NRF2 is critical for protecting the liver against disease by activating the transcription of genes encoding detoxification/antioxidant enzymes. We aimed to determine if the NRF2 pathway plays a significant role in the protection against hepatic iron overload. Wild-type and Nrf2(-/-) mouse primary hepatocytes were incubated with ferric ammonium citrate. Wild-type and Nrf2(-/-) mice were fed standard rodent chow or iron-rich diet for 2 weeks, with or without daily injection of the antioxidant mito-TEMPOL. In mouse hepatocytes, iron induced the nuclear translocation of NRF2 and the expression of cytoprotective genes in an NRF2-dependent manner. Moreover, Nrf2(-/-) hepatocytes were highly susceptible to iron-induced cell death. Wild-type and Nrf2(-/-) mice fed iron-rich diet accumulated similar amounts of iron in the liver and were equally able to increase the expression of hepatic hepcidin and ferritin. Nevertheless, in Nrf2-null mice the iron loading resulted in progressive liver injury, ranging from mild confluent necrosis to severe necroinflammatory lesions. Hepatocytic cell death was associated with gross ultrastructural damage to the mitochondria. Notably, liver injury was prevented in iron-fed animals that received mito-TEMPOL. NRF2 protects the mouse liver against the toxicity of dietary iron overload by preventing hepatocytic cell death. We identify NRF2 as a potential modifier of liver disease in iron overload pathology and show the beneficial effect of the antioxidant mito-TEMPOL in a mouse model of dietary iron-induced liver injury.
    Journal of Hepatology 09/2013; · 9.86 Impact Factor
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    ABSTRACT: Iron plays a central role in host-parasite interactions, since both intervenients need iron for survival and growth, but are sensitive to iron-mediated toxicity. The host's iron overload is often associated with susceptibility to infection. However, it has been previously reported that iron overload prevented the growth of , an agent of cutaneous leishmaniasis, in BALB/c mice. In order to further clarify the impact of iron modulation on the growth of , we studied the effects of iron supplementation or deprivation on the growth of , the causative agent of Mediterranean visceral leishmaniasis, in the mouse model. We found that dietary iron deficiency did not affect the protozoan growth, whereas iron overload decreased its replication in the liver and spleen of a susceptible mouse strain. The fact that the iron-induced inhibitory effect could not be seen in mice deficient in NADPH dependent oxidase or nitric oxide synthase 2 suggests that iron eliminates through the interaction with reactive oxygen and nitrogen species. Iron overload did not significantly alter the mouse adaptive immune response against . Furthermore, the inhibitory action of iron towards was also observed, in a dose dependent manner, in axenic cultures of promastigotes and amastigotes. Importantly, high iron concentrations were needed to achieve such effects. In conclusion, externally added iron synergizes with the host's oxidative mechanisms of defense in eliminating from mouse tissues. Additionally, the direct toxicity of iron against suggests a potential use of this metal as a therapeutic tool or the further exploration of iron anti-parasitic mechanisms for the design of new drugs.
    PLoS Neglected Tropical Diseases 02/2013; 7(2):e2061. · 4.57 Impact Factor
  • Fish Pathology 01/2012; 47(2):80-82. · 0.76 Impact Factor
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    ABSTRACT: Anaemia is a frequent complication of chronic infectious diseases but the exact mechanisms by which it develops remain to be clarified. In the present work, we used a mouse model of mycobacterial infection to study molecular alterations of iron metabolism induced by infection. We show that four weeks after infection with Mycobacterium avium BALB/c mice exhibited a moderate anaemia, which was not accompanied by an increase on hepatic hepcidin mRNA expression. Instead, infected mice presented increased mRNA expression of ferroportin (Slc40a1), ceruloplasmin (Cp), hemopexin (Hpx), heme-oxygenase-1 (Hmox1) and lipocalin-2 (Lcn2). Both the anaemia and the mRNA expression changes of iron-related genes were largely absent in C.D2 mice which bear a functional allele of the Nramp1 gene. Data presented in this work suggest that anaemia due to a chronic mycobacterial infection may develop in the absence of elevated hepcidin expression, is influenced by Nramp1 and may involve lipocalin-2.
    Immunobiology 04/2011; 216(10):1127-34. · 2.81 Impact Factor
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    ABSTRACT: Hereditary hemochromatosis (HH), a widespread hereditary iron metabolism disorder, is characterized by an excessive absorption of dietary iron, resulting in increased body iron stores. Some studies indicate a sex difference in disease expression, with women showing a slower disease progression and a less severe clinical profile. This is usually attributed to iron loss during menstruation and pregnancy. However, this link has not been clearly demonstrated. The Hfe-/- mouse model recapitulates key aspects of HH, including an iron overload phenotype similar to that observed in human patients. In this study, we use it to test the impact of multiple pregnancies in the iron stores. One-year-old nulliparous and pluriparous (averaging 29 weaned pups per female) C57BL/6 (B6) and Hfe-/- mice were euthanized, and blood and tissues were collected. Several serological and erythroid parameters were evaluated, as well as tissue nonheme iron content and serum ferritin. Hepcidin 1, hepcidin 2, and bone morphogenetic protein 6 (BMP6) expressions in the liver were determined by real-time PCR. No significant differences were observed for many serological and erythroid parameters although differences occurred in transferrin saturation and mean corpuscular volume in Hfe-/- mice and total iron-binding capacity in B6 mice. Hepatic iron concentration was similar for nulliparous and pluriparous mice of both genotypes, but total iron per organ (liver, spleen, heart, and pancreas) was higher overall in pluriparous females than nulliparous. Hepcidin 1 and 2 and BMP6 expressions were significantly decreased in pluriparous females, when compared with nulliparous, in both genotypes. In conclusion, multiple pregnancies do not reduce body iron stores in Hfe-/- mice.
    AJP Gastrointestinal and Liver Physiology 04/2010; 298(4):G525-9. · 3.65 Impact Factor
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    ABSTRACT: Background / Purpose: Recent evidence suggests the involvement of lymphocytes in the severity of iron overload disorders, but no mechanisms have been suggested to explain these observations.We show that hepcidin is expressed in PBLs and is up-regulated in response to holotransferrin and ferric citrate. This ability to increase hepcidin expression in response to ferric citrate distinguishes lymphocytes from hepatocytes and places PBLs as a first line of response to increases in transferrin saturation and presence of nontransferrin-bound iron, characteristic of iron overload disorders. Main conclusion: The results further show a role for hepcidin expression in the control of T lymphocyte proliferation, via regulation of ferroportin-mediated iron export. Our results put forward a molecular mechanism for the described modifier role of lymphocytes in protection from iron toxicity.
    51st American Society of Hematology Annual Meeting 2009; 03/2010
  • J.V. Neves, I.A.S. Olsson, G. Porto, P.N. Rodrigues
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    ABSTRACT: Export Date: 18 November 2011, Source: Scopus
    American Journal of Physiology - Gastrointestinal and Liver Physiology. 01/2010; 298:G525-G529.
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    ABSTRACT: Mice expressing a vav-bcl-2 transgene were tested for their resistance to an experimental infection with Mycobacterium avium. When compared with control littermates, transgenic mice exhibited an increase in the resistance to infection which was independent of B or T lymphocytes and did not require the production of gamma interferon. Macrophages from both control and transgenic mice showed equal permissiveness to M. avium growth in vitro. Finally, transgenic mice expressed diminished circulating iron levels which correlated with the increased resistance to infection.
    Clinical & Experimental Immunology 02/2009; 156(1):61-8. · 3.41 Impact Factor
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    ABSTRACT: Mycobacterium avium is an opportunistic infectious agent in immunocompromised patients, living inside macrophage phagosomes. As for other mycobacterial species, iron availability is a critical factor for M. avium survival and multiplication. Indeed, an association between host secondary iron overload and increased susceptibility to these mycobacteria is generally acknowledged. However, studies on the impact of primary iron overload on M. avium infection have not been performed. In this work, we used animal models of primary iron overload that mimic the human disease hereditary hemochromatosis. This pathology is characterized by increased serum transferrin saturation with iron deposition in parenchymal cells, mainly in the liver, and is most often associated with mutations in the gene encoding the molecule HFE. In this paper, we demonstrate that mice of two genetically determined primary iron overload phenotypes, Hfe(-/-) and beta2m(-/-), show an increased susceptibility to experimental infection with M. avium and that during infection these animals accumulate iron inside granuloma macrophages. beta2m(-/-) mice were found to be more susceptible than Hfe(-/-) mice, but depleting Hfe(-/-) mice of CD8(+) cells had no effect on resistance to infection. Overall, our results suggest that serum iron, rather than total liver iron, levels have a considerable impact on susceptibility to M. avium infection.
    Infection and immunity 09/2008; 76(10):4713-9. · 4.21 Impact Factor
  • International Journal of Antimicrobial Agents 03/2007; 29. · 4.42 Impact Factor
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    ABSTRACT: Hepatic iron overload in hemochomatosis patients can be highly variable but in general it develops in older patients. The purpose of this study was to compare development of iron load in of beta2m-/- and Hfe-/- mice paying special attention to liver pathology in older age groups. Liver iron content of beta2m-/-, Hfe-/- and control B6 mice of different ages (varying from 3 weeks to 18 months) was examined. Additional parameters (haematology indices, histopathology, lipid content and ferritin expression) were also studied in 18-month-old mice. The beta2m-/- strain presents higher hepatic iron content, hepatocyte nuclear iron inclusions, mitochondria abnormalities. In addition, hepatic steatosis was a common observation in this strain. In the liver of Hfe-/- mice, large mononuclear infiltrates positive for ferritin staining were commonly observed. The steatosis commonly observed the beta2m-/- mice may be a reflection of its higher hepatic iron content. The large hepatic mononuclear cell infiltrates seen in Hfe-/- stained for ferritin, may point to the iron sequestration capacity of lymphocytes and contribute to the clarification of the differences found in the progression of hepatic iron overload and steatosis in older animals from the two strains.
    International Journal of Experimental Pathology 09/2006; 87(4):317-24. · 2.04 Impact Factor
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    ABSTRACT: Background: Despite heavy alcohol consumption, only a low percentage of heavy drinkers develop liver disease. Imbalances in T-cell subsets and iron metabolism parameters are common findings in heavy drinkers, yet the possible role played by discrete T-lymphocyte subsets under heavy alcohol consumption remains unclear.Methods: To gain new insights into the possible role played by T lymphocytes during alcohol consumption, characterization of CD28 expression and TcR repertoire in peripheral blood CD4+ and CD8+ T cells by two and three-color flow cytometry was performed. A group of heavy alcohol drinkers (AHD, n= 71) and a group of age-matched controls (n= 81), both HLA-phenotyped and HFE-genotyped, constituted the groups under study.Results: Marked expansions of CD28− T cells within the CD8+ but not the CD4+ T-cell pool were observed in AHD compared with controls. These CD8+CD28− expansions were paralleled by expansions of CD8+ T cells bearing specific TcR Vα/β chains, namely Vβ5.2. Moreover, AHD, but not controls, carrying the H63D mutation in the HFE gene showed significantly higher percentages of CD28− T cells within the CD8+ T-cell pool than AHD carrying the normal HFE gene. Finally, high numbers of CD8+CD28− T cells in AHD were associated with lower levels of the liver-related enzymes ALT and GGT.Conclusions: This study showed that under active ethanol consumption, expansions of discrete CD8+ T-cell subsets occur within the CD8+ T-cell pool, that molecules of the MHC-class I locus seem to influence the extent of the expansions, and that high numbers of CD8+CD28− T cells are associated with low levels of liver enzymes in AHD.
    Alcoholism Clinical and Experimental Research 04/2006; 24(4):519 - 527. · 3.42 Impact Factor
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    ABSTRACT: Iron overload in the liver may occur in clinical conditions such as hemochromatosis and nonalcoholic steatohepatitis, and may lead to the deterioration of the normal liver architecture by mechanisms not well understood. Although a relationship between the expression of ICAM-1, and classical major histocompatibility complex (MHC) class I molecules, and iron overload has been reported, no relationship has been identified between iron overload and the expression of unconventional MHC class I molecules. Herein, we report that parameters of iron metabolism were regulated in a coordinated-fashion in a human hepatoma cell line (HepG2 cells) after iron loading, leading to increased cellular oxidative stress and growth retardation. Iron loading of HepG2 cells resulted in increased expression of Nor3.2-reactive CD1d molecules at the plasma membrane. Expression of classical MHC class I and II molecules, ICAM-1 and the epithelial CD8 ligand, gp180 was not significantly affected by iron. Considering that intracellular lipids regulate expression of CD1d at the cell surface, we examined parameters of lipid metabolism in iron-loaded HepG2 cells. Interestingly, increased expression of CD1d molecules by iron-loaded HepG2 cells was associated with increased phosphatidylserine expression in the outer leaflet of the plasma membrane and the presence of many intracellular lipid droplets. These data describe a new relationship between iron loading, lipid accumulation and altered expression of CD1d, an unconventional MHC class I molecule reported to monitor intracellular and plasma membrane lipid metabolism, in the human hepatoma cell line HepG2.
    FEBS Journal 02/2005; 272(1):152-65. · 4.25 Impact Factor
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    ABSTRACT: Beta2-microglobulin knockout (beta2m-/-) mice represent an instructive model of spontaneous iron overload resembling genetic hemochromatosis. The mechanism of iron accumulation in this mouse model may be more complex than involving the MHC class I-like protein HFE. We report that beta2m-deficient mice, like Hfe-/- mice, lack the adaptive hepatic hepcidin mRNA increase to iron overload. The inverse correlation of hepatic iron levels and hepcidin mRNA expression in six beta2m-/- mice underlines the importance of hepcidin in regulating body iron stores. In contrast to Hfe-/- mice, beta2m-deficient mice display increased expression of the duodenal iron transporters DMT1 and ferroportin 1. This result implicates a broader role of beta2m in mammalian iron metabolism, suggesting that (an) additional beta2m-interacting protein(s) could be involved in controlling iron homeostasis, and highlighting the emerging connection of iron metabolism with the immune system.
    Blood Cells Molecules and Diseases 09/2004; 33(2):125-31. · 2.26 Impact Factor
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    ABSTRACT: Host factors that may influence progression of hepatitis C infection to chronic hepatitis include T-cell responses and iron accumulation. We evaluated the hepatic expression of immunological markers relevant for a cytotoxic response in relation to viral and HFE genotype. Frozen liver biopsies were obtained at diagnosis from 28 HFE genotyped patients. Sections stained for CD8, MHC-I, beta(2)m, HFE and CD68 were analyzed blind by morphometry. Response to therapy was available in 12 cases. A negative correlation was found between the number of CD8(+) cells and fibrosis. CD8(+) cells localized as clusters in portal tracts and sinusoids and were seen interacting with MHC-I positive lining cells. MHC-I and beta(2)m were expressed mainly in the endothelial and Kupffer cells. HFE was expressed in most, but not all, round and dendritic CD68(+) cells. Patients with virus genotype 3a had higher hepatic MHC-I and HFE expression, and a better-sustained response to IFN therapy than other patients. In chronic hepatitis C virus infection MHC-I expression in the liver seems to relate to viral-genotype. In addition, the expression of MHC-I molecules by Kupffer cells places them as probable important players in the host response to HCV.
    Journal of Hepatology 09/2004; 41(2):319-26. · 9.86 Impact Factor
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    ABSTRACT: Variability in T-lymphocyte numbers is partially explained by a genetic regulation. From studies in animal models, it is known that the Major Histocompatibility Complex (MHC) is involved in this regulation. In humans, this has not been shown yet. The objective of the present study was to test the hypothesis that genes in the MHC region influence the regulation of T-lymphocyte numbers. Two approaches were used. Association studies between T-cell counts (CD4(+) and CD8(+)) or total lymphocyte counts and HLA class I alleles (A and B) or mutations in the HFE (C282Y and H63D), the hemochromatosis gene, in an unrelated population (n = 264). A second approach was a sibpair correlation analysis of the same T-cell counts in relation to HLA-HFE haplotypes in subjects belonging to 48 hemochromatosis families (n = 456 sibpairs). In the normal population, results showed a strong statistically significant association of the HLA-A*01 with high numbers of CD8(+) T cells and a less powerful association with the HLA-A*24 with low numbers of CD8(+) T cells. Sibpair correlations revealed the most significant correlation for CD8(+) T-cell numbers for sibpairs with HLA-HFE-identical haplotypes. This was not observed for CD4(+) T cells. These results show that the MHC region is involved in the genetic regulation of CD8(+) T-cell numbers in humans. Identification of genes responsible for this control may have important biological and clinical implications.
    Tissue Antigens 08/2004; 64(1):25-34. · 2.93 Impact Factor
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    ABSTRACT: Hereditary hemochromatosis (HH) is classically associated with a Cys282Tyr (C282Y) mutation of the HFE gene. Non-C282Y HH is a heterogeneous group accounting for 15% of HH in Northern Europe. Pathogenic mutations of the transferrin receptor 2 (TfR2) gene have been identified in 4 Italian pedigrees with the latter syndrome. The goal of this study was to perform a mutational analysis of the TfR2 and HFE genes in a cohort of non-C282Y iron overload patients of mixed ethnic backgrounds. Several sequence variants were identified within the TfR2 gene, including a homozygous missense change in exon 17, c2069 A-->C, which changes a glutamine to a proline residue at position 690. This putative mutation was found in a severely affected Portuguese man and 2 family members with the same genotype. In summary, pathologic TfR2 mutations are present outside of Italy, accounting for a small proportion of non-C282Y HH.
    Blood 08/2002; 100(3):1075-7. · 9.78 Impact Factor

Publication Stats

279 Citations
94.26 Total Impact Points

Institutions

  • 2000–2014
    • Institute for Molecular and Cell Biology
      Oporto, Porto, Portugal
  • 2008–2013
    • University of Porto
      • Institute for Molecular and Cell Biology
      Porto, Distrito do Porto, Portugal
    • Polytechnic Institute of Porto
      Oporto, Porto, Portugal
  • 2004
    • Instituto de Ciencias
      Santa Clara de Portugal, Michoacán, Mexico
    • European Molecular Biology Laboratory
      Heidelburg, Baden-Württemberg, Germany