Leandra Naira Zambelli Ramalho

Functional Characterization of an Aspergillus fumigatus Calcium Transporter (PmcA) that Is Essential for Fungal Infection

Aspergillus fumigatus is a primary and opportunistic pathogen, as well as a major allergen, of mammals. The Ca+2-calcineurin pathway affects virulence, morphogenesis and antifungal drug action in A. fumigatus. Here, we investigated three components of the A. fumigatus Ca+2-calcineurin pathway, pmcA,-B, and -C, which encode calcium transporters. We demonstrated that CrzA can directly control the mRNA accumulation of the pmcA-C genes by binding to their promoter regions. CrzA-binding experiments suggested that the 5′-CACAGCCAC-3′ and 5′-CCCTGCCCC-3′ sequences upstream of pmcA and pmcC genes, respectively, are possible calcineurin-dependent response elements (CDREs)-like consensus motifs. Null mutants were constructed for pmcA and -B and a conditional mutant for pmcC demonstrating pmcC is an essential gene. The ΔpmcA and ΔpmcB mutants were more sensitive to calcium and resistant to manganese and cyclosporin was able to modulate the sensitivity or resistance of these mutants to these salts, supporting the interaction between calcineurin and the function of these transporters. The pmcA-C genes have decreased mRNA abundance into the alveoli in the ΔcalA and ΔcrzA mutant strains. However, only the A. fumigatus ΔpmcA was avirulent in the murine model of invasive pulmonary aspergillosis.

The Relationship Between p63 and p53 Expression in Normal and Neoplastic Breast Tissue

CONTEXT p63 is a recently described p53 homologue. Despite structural homology, they have different activities. OBJECTIVES To obtain new insights into the role of p63 in normal and neoplastic breast tissue and to verify the possible association between p63 and p53 in breast carcinomas. DESIGN Immunohistochemistry in 85 breast carcinomas using p63, smooth muscle actin (1A4), p53, estrogen receptor, and progesterone receptor. The p63-positive cases were submitted to a double-immunolabeling study using p63 with 1A4, cytokeratin 7, and 34betaE12. Clinical data were retrieved from medical files. RESULTS p63, like 1A4, stained a single and continuous layer surrounding normal breast ductal and alveolar epithelium. In carcinomas, p53 was expressed in 21.17% of carcinomas, whereas p63 was expressed only in poorly differentiated ductal carcinomas (11.76% of cases). p63-positive cells coexpressed 1A4 and 34betaE12, but not cytokeratin 7. Expression of p63 correlated with pathologic staging, tumor size, histologic grading, nodal metastasis, and estrogen receptor negativity. CONCLUSIONS p63 is a specific myoepithelial cell marker in normal breast tissue and is expressed in a minority of breast carcinomas, being seen only in grade III ductal carcinomas. In ductal carcinomas, malignant p63-positive cells have an immunophenotype similar to that of myoepithelial cells, suggesting that these cells originate from a primary progenitor cell that underwent divergent differentiation to ductal and myoepithelial cells during clonal expansion. Our study argues against a direct role in mammary tumorigenesis. However, p53 is rarely coexpressed with p63, suggesting that p63 could act indirectly as an oncogene by inhibiting p53. This hypothesis could also explain why p63 correlated with several other indicators of poor prognosis.

Are Haemochromatosis Mutations Related to the Severity of Liver Disease in Hepatitis C Virus Infection

It has been proposed that iron overload may adversely affect liver disease outcome. The recent identification of 2 mutations in the HFE gene related to hereditary haemochromatosis (Cys282Tyr and His63Asp) provided an opportunity to test whether they are associated with hepatic iron accumulation and the activity and severity of liver disease in hepatitis C virus (HCV) infection. We investigated the prevalence of HFE mutations in 135 male patients with chronic HCV hepatitis, and correlated genotype distribution with different parameters of iron status and the activity and severity of liver disease. Of these 135 patients, 6 (4.4%) carried Cys282Tyr and 32 (23.7%) carried His63Asp, frequencies which were similar to those observed in healthy controls. Serum iron levels and transferrin saturation (but not ferritin levels or liver iron content) were significantly higher in carriers than in non-carriers of HFE mutations. No difference was observed in serum ALT, AST and GGT levels between carriers and non-carriers. Finally, scores for necroinflammatory activity and fibrosis in the liver were significantly higher in HFE carriers than in non-carriers. Patients with chronic HCV infection carrying HFE mutations tend to present more evident body iron accumulation and a higher degree of necroinflammatory activity and fibrosis in the liver. HFE gene mutations might be an additional factor to be considered among those implicated in the determination of a worse prognosis of the liver disease in chronic HCV infection.

Nonalcoholic Steatohepatitis: A Search for Factual Animal Models

Nonalcoholic fatty liver disease (NAFLD) is characterized by hepatic steatosis, which occurs in the absence of alcohol abuse. NAFLD can evolve into progressive liver injury and fibrosis in the form of nonalcoholic steatohepatitis (NASH). Several animal models have been developed to attempt to represent the morphological, biochemical, and clinical features of human NASH. The actual review presents a critical analysis of the most commonly used experimental models of NAFLD/NASH development. These models can be classified into genetic, nutritional, and a combination of genetic and nutritional factors. The main genetic models are ob/ob and db/db mutant mice and Zucker rats. The principal nutritional models employ methionine- and choline-deficient, high-fat, high-cholesterol and high-cholate, cafeteria, and high-fructose diets. Currently, associations between high-fructose and various compositions of high-fat diets have been widely studied. Previous studies have encountered significant difficulties in developing animal models capable of reproducing human NASH. Some models produce consistent morphological findings, but the induction method differs significantly compared with the pathophysiology of human NASH. Other models precisely represent the clinical and etiological contexts of this disease but fail to provide accurate histopathological representations mainly in the progression from steatosis to liver fibrosis.

Biochemical analysis of human breast tissues using Fourier-transform Raman spectroscopy

We employ Fourier-transform Raman spectroscopy to study normal and tumoral human breast tissues, including several subtypes of cancers. We analyzed 194 Raman spectra from breast tissues that were separated into 9 groups according to their corresponding histopathological diagnosis. The assignment of the relevant Raman bands enabled us to connect the several kinds of breast tissues (normal and pathological) to their corresponding biochemical moieties alterations and distinguish among 7 groups: normal breast, fibrocystic condition, duct carcinoma in situ, duct carcinoma in situ with necrosis, infiltrating duct carcinoma not otherwise specified, colloid infiltrating duct carcinoma, and invasive lobular carcinomas. We were able to establish the biochemical basis for each spectrum, relating the observed peaks to specific biomolecules that play a special role in the carcinogenesis process. This work is very useful for the premature optical diagnosis of a broad range of breast pathologies. We noticed that we were not able to differentiate inflammatory and medullary duct carcinomas from infiltrating duct carcinoma not otherwise specified.

Hepatic stellate cells in hepatitis C patients: Relationship with liver iron deposits and severity of liver disease

Background and Aim:  To determine the relationship between hepatic stellate cell (HSC) populations and severity of liver disease and liver iron deposits in patients with chronic hepatitis C virus (HCV). We also studied the relationship between iron cellular distribution and HSC population and the role of HFE mutations in the determination of iron deposits.

Porphyria cutanea tarda in Brazilian patients: association with hemochromatosis C282Y mutation and hepatitis C virus infection

OBJECTIVE:Porphyria cutanea tarda (PCT) is commonly associated with iron overload and hepatitis C virus (HCV) infection. Association between hemochromatosis C282Y or H63D mutations and PCT has been observed, although not uniformly, and iron overload is also commonly found in chronic HCV hepatitis. The aim of the present study was to investigate the frequency of C282Y and H63D mutations and HCV infection in Brazilian patients with PCT and their relationship with iron overload.METHODS:Twenty-three patients (19 men) aged 39.6 ± 11.1 yr were studied. All had dermatological lesions of PCT and high levels of urinary uroporphyrin. HCV infection and iron overload were investigated. DNA samples were analyzed for the presence of HFE mutations.RESULTS:The frequency of C282Y was significantly higher in PCT patients than in 278 healthy individuals (17.4% vs 4%, odds ratio = 5.1, 95% confidence interval 1.5–17.6, p= 0.02), whereas no difference was observed regarding the H63D mutation (30.4% vs 31%, odds ratio = 1, 95% confidence interval 0.4–2.4, p= 1). Biochemical tests in PCT patients showed iron overload with transferrin saturation = 47.3 ± 20.7% and ferritin = 566.8 ± 425 ng/ml. Fifteen of 23 (65.2%) patients had HCV infection and alcohol ingestion was observed in 17 of 23 (73.9%).CONCLUSIONS:PCT patients exhibited evidence of iron overload, a high frequency of HCV, and an association with C282Y mutation. These data further support the notion that both acquired and inherited factors contribute to the occurrence of PCT, and indicate that screening for C282Y may be justified in PCT patients.

Dynamic changes of the Th17/Tc17 and regulatory T cell populations interfere in the experimental autoimmune diabetes pathogenesis.

A balance between proinflammatory (Th17 and Tc17) and anti-inflammatory (regulatory T cells) subsets of T cells is essential to maintain immunological tolerance and prevent the onset of several autoimmune diseases, including type 1 diabetes. However, the kinetics of these subsets and disease severity during the streptozotocin (STZ)-induced diabetes course has not been determined. Thus, susceptible C57BL/6 mice were administrated with multiple low doses of STZ and we evaluated the frequency/absolute number of these T cell subsets in the pancreatic lymph nodes (PLNs) and spleen and Th1, Th17, Treg cytokine production in the pancreatic tissue. At different time points of the disease progression (6, 11, 18 and 25 days after the last STZ administration), the histopathological alterations were also evaluated by H&E and immunohistochemistry staining. During the initial phase of diabetes development (day 6), we noted increased numbers of CD4(+) and CD8(+) T cells in spleen and PLNs. At the same time, the frequencies of Th17 and Tc17 cells in PLNs were also enhanced. In addition, the early augment of interferon gamma (IFN-γ), tumoral necrosis factor (TNF-α), IL-6 and IL-17 levels in pancreatic tissue correlated with pancreatic islet inflammation and mild β-cell damage. Notably, the absolute number of Treg cells increased in PLNs during over time when compared to control group. Interestingly, increased IL-10 levels were associated with control of the inflammatory process during the late phase of the type 1 diabetes (day 25). In agreement, mice lacking the expression of IL-17 receptor (Il17r) showed impairment in STZ-induced diabetes progression, reduced peri-insulitis and beta cells preservation when compared with wild-type mice. Our findings suggest that dynamic changes of pathogenic Th17/Tc17 and regulatory T cell subsets numbers is associated with early strong inflammation in the pancreatic islets followed by late regulatory profile during the experimental STZ-induced diabetes course.

Molecular Characterization of the Putative Transcription Factor SebA Involved in Virulence in Aspergillus fumigatus

ABSTRACT Aspergillus fumigatus is a major opportunistic pathogen and allergen of mammals. Nutrient sensing and acquisition mechanisms, as well as the capability to cope with different stressing conditions, are essential for A. fumigatus virulence and survival in the mammalian host. This study characterized the A. fumigatus SebA transcription factor, which is the putative homologue of the factor encoded by Trichoderma atroviride seb1. The ΔsebA mutant demonstrated reduced growth in the presence of paraquat, hydrogen peroxide, CaCl2, and poor nutritional conditions, while viability associated with sebA was also affected by heat shock exposure. Accordingly, SebA::GFP (SebA::green fluorescent protein) was shown to accumulate in the nucleus upon exposure to oxidative stress and heat shock conditions. In addition, genes involved in either the oxidative stress or heat shock response had reduced transcription in the ΔsebA mutant. The A. fumigatus ΔsebA strain was attenuated in virulence in a murine model of invasive pulmonary aspergillosis. Furthermore, killing of the ΔsebA mutant by murine alveolar macrophages was increased compared to killing of the wild-type strain. A. fumigatus SebA plays a complex role, contributing to several stress tolerance pathways and growth under poor nutritional conditions, and seems to be integrated into different stress responses.

Wnt/β-Catenin Pathway Deregulation in Childhood Adrenocortical Tumors

CONTEXT CTNNB1/β-catenin mutations and activation of Wnt/β-catenin pathway are frequent in adult adrenocortical tumors (ACT), but data on childhood ACT are lacking. OBJECTIVE The aim of the study was to investigate the presence of Wnt/β-catenin pathway abnormalities in childhood ACT. PATIENTS AND METHODS Clinicopathological findings and outcome of 62 childhood ACT patients were analyzed regarding CTNNB1 mutations and the expression of Wnt-related genes (CTNNB1; WNT4, a Wnt ligand; SFRP1, DKK3, and AXIN1, Wnt inhibitors; TCF7, a transcription factor; and MYC and WISP2, target genes) by quantitative PCR and immunohistochemistry. RESULTS CTNNB1-activating mutations were found in only four of 62 ACT (6%), all of them harboring TP53 mutation. There was association between the presence of CTNNB1 mutations and death (P = 0.02). Diffuse β-catenin accumulation was found in 71% of ACT, even in ACT without CTNNB1 mutations. Compared to normal adrenals, ACT presented increased expression of CTNNB1 (P = 0.008) and underexpression of Wnt inhibitor genes: DKK3 (P < 0.0001), SFRP1 (P = 0.05), and AXIN1 (P = 0.04). With regard to Wnt/β-catenin target genes, ACT presented increased expression of WISP2 but lower expression of MYC. Higher overall survival was associated with underexpression of SFRP1 (P = 0.01), WNT4 (P = 0.004), and TCF7 (P < 0.01). CONCLUSIONS CTNNB1 mutations are not common in childhood ACT but appear to associate with poor prognosis. Nevertheless, most ACT exhibit increased expression of β-catenin and WISP2 and reduced expression of Wnt inhibitor genes (DKK3, SFRP1, and AXIN1). Thus, in addition to CTNNB1 mutations, other genetic events affecting the Wnt/β-catenin pathway may be involved in childhood adrenocortical tumorigenesis.