In vitro antifungal susceptibility of candida albicans isolates from patients with chronic periodontitis and diabetes

Alterations that lead to deficiency of the immune system, such as diabetes mellitus, may promote proliferation of Candida albicans and selection of strains which have greater ability to adhere and to penetrate the host tissues. Recent studies indicate an increase of the antifungal resistance of C. albicans isolates in periodontal pockets, suggesting that the oral cavity could be a reservoir of resistant yeast to antifungal agents. Moreover, oral cavity can act as a reservoir of certain pathogens that may cause systemic infections. The periodontal pocket is an ecological niche suitable to host microorganisms that could act as opportunistic pathogens. The aim of this study is to contribute to the understanding of resistance to conventional antifungal against C. albicans isolates from patients with periodontitis and diabetes. The determination of the minimal inhibitory concentrations (MIC) was evaluated according to M27S3 of the CLSI (2008), with modifications. The results showed that 48.8% of the studied strains were resistant to one or more antifungals and 6.6% were resistant to fluconazole and voriconazole. These results suggest an increasing resistance to conventional antifungal agents among Candida species, suggesting that the oral cavity could host pathogen fungi.

Atividade da fração enriquecida em fenólicos de Buchenavia tomentosa e de algumas substâncias isoladas antes e após encapsulação com beta-ciclodextrina em Candida albicans

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo de genes de Candida albicans com função desconhecida quanto à formação de biofilme, características biológicas e interação patógeno- hospedeiro

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influência de Lactobacillus rhamnosus na patogenicidade e na expressão de genes de virulência de Candida albicans: estudo in vitro e in vivo

Pós-graduação em Biopatologia Bucal - ICT

Síntese e atividade anti-HCV, anti-candida e antibacteriana de nitrochalconas

Pós-graduação em Química - IBILCE

Efeito da infecção com Candida albicans no desenvolvimento da Encefalomielite Autoimune Experimental

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Interação Candida albicans COM Acinetobacter baumannii E Klebsiella pneumoniae em biofilmes multiespécies

Pós-graduação em Biopatologia Bucal - ICT

Desinfecção fotoeletrocatalítica de águas contaminadas com Candida Parapsilosis utilizando eletrodos de W/WO3 em tratamento fotoeletrocatalítico

Pós-graduação em Química - IQ

Terpinen-4-ol: estudo do efeito sinérgico/aditivo, adesão em co-cultura e alteração dos fatores de virulência sobre Candida spp

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeito do farnesol sobre fatores de virulência de Candida albicans e Streptococcus mutans

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Physiological Studies on Candida albicans

Candida albicans is a common opportunistic, dimorphic human fungal pathogen. One of its virulence factors is the morphological switch between yeasts and hyphal or pseudohyphal forms, which can invade tissues and cause damage. Our studies focus on factors regulating pseudohyphae and epigenetic modifications of C. albicans. Regulating factors of pseudohyphae are aromatic alcohols and high phosphate. At low concentrations, exogenous aromatic alcohols induced pseudohyphae, as did high phosphate. For addressing the pathways involved in inducing pseudohyphae by aromatic alcohols or high phosphate, we used mutants defective in cAMP dependent PKA pathway (efg1/efg1), MAP kinase pathway (cph1/cph1), or both (cph1/cph1/efg1/efg1). These mutants failed to produce either hyphae or pseudohyphae in the presence of aromatic alcohols; but high phosphate still stimulated pseudohyphae. Gcn4, a transcription activator of more than 500 amino acid related genes, is turned-on in response to amino acid starvation. The accumulation of aromatic alcohols sends nitrogen starvation signals, which inhibit eIF2B, which in turn derepresses Gcn4p. High phosphate also induces pseudohyphae by derepressing Gcn4p, although the pathways involved are still unknown. In sum, aromatic alcohols and high phosphate induce pseudohyphae by derepressing Gcn4. In this study we found a novel posttranslational histone modification in C. albicans, which is biotinylation. Western blot and Mass spectrometry techniques were used to find that Histones H2B and H4 were biotinylated at every condition tested such as yeast vs. hyphae, aerobic growth vs. anaerobic growth, rich medium vs. defined medium. In C. albicans lysines K8, K11 in histone H4 and lysines K17, K18, K31 in histone H2B are biotin attachment sites as found using mass spectrometry. Biotin was also found to enhance the germ tube formation of C. albicans. Germ tube formation assays with biotin-starved cells as inoculum showed low percent of germ tubes (1-5%). Addition of biotin to the media showed 100% germ tubes. Biotinylation of histones were not detected from biotin-starved cells. Appendix-A details work related to Farnesol quantification assays in several strains of C.albicans and Ceratocystis ulmi, and growth studies of class E VPS strains of Saccharomyces Cerevisiae. Adviser: Kenneth W. Nickerson

Efeito do farnesol sobre fatores de virulência de Candida albicans e Streptococcus mutans

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Dendritic cells from X-linked hyper-IgM patients present impaired responses to Candida albicans and Paracoccidioides brasiliensis

Background: Patients with X-linked hyper-IgM syndrome (X-HIGM) due to CD40 ligand (CD40L) mutations are susceptible to fungal pathogens; however, the underlying susceptibility mechanisms remain poorly understood. Objective: To determine whether monocyte-derived dendritic cells (DCs) from patients with X-HIGM exhibit normal responses to fungal pathogens. Methods: DCs from patients and controls were evaluated for the expression of costimulatory (CD80 and CD86) and MHC class II molecules and for their ability to produce IL-12 and IL-10 in response to Candida albicans and Paracoccidioides brasiliensis. We also evaluated the ability of C albicans- and P brasiliensis-pulsed mature DCs to induce autologous T-cell proliferation, generation of T helper (T-H) 17 cells, and production of IFN-gamma, TGF-beta, IL-4, IL-5, and IL-17. Results: Immature DCs from patients with X-HIGM showed reduced expression of CD80, CD86, and HLA-DR, which could be reversed by exogenous trimeric soluble CD40L. Most important, mature DCs from patients with X-HIGM differentiated by coculturing DCs with fungi secreted minimal amounts of IL-12 but substantial amounts of IL-10 compared with mature DCs from normal individuals. Coculture of mature DCs from X-HIGM patients with autologous T cells led to low IFN-g production, whereas IL-4 and IL-5 production was increased. T-cell proliferation and IL-17 secretion were normal. Finally, in vitro incubation with soluble CD40L reversed the decreased IL-12 production and the skewed T-H(2) pattern response. Conclusion: Absence of CD40L during monocyte/DC differentiation leads to functional DC abnormalities, which may contribute to the susceptibility to fungal infections in patients with X-HIGM. (J Allergy Clin Immunol 2012; 129: 778-86.)

The pattern recognition receptors expressed on neutrophils and the associated cytokine profile from different aged patients with Candida-related denture stomatitis

This study evaluated the expression of pattern recognition receptors (PRRs) and activation factors associated with salivary and blood neutrophils from different aged patients diagnosed with Candida-related denture stomatitis (DS). Expression of neutrophil PRRs was determined by flow cytometry and immunofluorescence, and the levels of selected cytokines that influence immune activation were determined by ELISA. The salivary (but not the serum derived) neutrophils of individuals with DS were found to have an increased expression of CD69 regardless of the age of the patient compared to patients without DS. However, these salivary neutrophils had a lower expression of CD66b and CD64. Expression of TLR2 was lower on the salivary-and serum-derived neutrophils from elderly individuals compared to the neutrophils of younger subjects, regardless of whether the individual had DS. Salivary interleukin (IL)-4 was elevated in both of the elderly subject groups (with or without DS). Only elderly DS patients were observed to have increased serum IL-4 levels and reduced salivary IL-12 levels. Younger DS patients showed an increase in salivary IL-10 levels, and both the saliva and the serum levels of IFN-gamma were increased in all of the younger subjects. Our data demonstrated that changes in both the oral immune cells and the protein components could be associated with DS. Furthermore, changes in the blood-derived factors were more associated with age than DS status. (C) 2012 Elsevier Inc. All rights reserved.

Virulence attributes and genetic variability of oral Candida albicans and Candida tropicalis isolates

The wide spectrum of candidiasis and its clinical importance encourage the research with the purpose of clarifying the mechanisms of pathogenicity and identification of virulence factors of Candida sp. Therefore, the aim of this study was to verify the adhesion capacity, protease activity and genotypic diversity of oral C. albicans and C. tropicalis isolates. The adhesion ability to the extracellular matrix glycoproteins laminin and fibronectin was evaluated using the ELISA technique. The research of proteases was carried out in agar plate containing bovine albumin and through a quantitative method in buffer solution containing haemoglobin. Intra and interspecies polymorphisms was verified through random amplified polymorphic DNA (RAPD) technique. All C. albicans and C. tropicalis isolates binded to immobilised laminin and fibronectin. Ca33 and Ct13 isolates had relative adhesion index significantly higher than the other isolates for both glycoproteins (P < 0.001). Protease activity was observed in all isolates of C. albicans using either the semi-quantitative or quantitative assay. The protease activity of C. tropicalis was better detected through the quantitative assay. The genotypic diversity by RAPD revealed a heterogeneous population in both species. Nevertheless, C. tropicalis presented higher genetic variability than C. albicans strains.