Ana Maria Gonçalves da Silva

Antigen distribution and antigen-presenting cells in skin biopsies of human chromoblastomycosis.

Background:  Chromoblastomycosis is a chronic, suppurative, granulomatous mycosis usually confined to skin and subcutaneous tissues. The host defense mechanisms in chromoblastomycosis have not been extensively investigated. The purpose of the present study was to determine the distribution and pathways of the fungal antigen(s) and the possible role of the different immunocompetent cells in antigen processing in skin lesions.

Immunohistochemical and in situ hybridization studies of the liver and kidney in human leptospirosis

An in situ hybridization (ISH) assay for the detection of leptospiral DNA in tissues was described and its diagnostic and pathogenetic usefulness in combination with immunohistochemistry (IHC) was evaluated in formalin-fixed, paraffin-embedded liver and kidney samples from human fatal cases of leptospirosis. IHC assays with anti-E-cadherin antibodies assessed the liver-plate disarray frequently observed in leptospirosis. Immunohistochemistry detected leptospiral antigen (LAg) in macrophages, both in human liver and kidney. In guinea pigs, in addition to these findings, staining on cell membranes of hepatocytes and, occasionally, in apical membrane of kidney tubular cells was demonstrated. Positive ISH signal was observed chiefly in the nuclei of human hepatocytes and in the cytoplasm and nuclei of liver cells of experimentally infected guinea pigs. Loss of E-cadherin membrane expression is associated with liver-plate disarray. These findings were discussed in the contention that, in leptospirosis, cell membrane damage might be important for the pathogenesis of the disease. Finally, it was suggested that both IHC and/or ISH might be used for both diagnostic and research purposes.

Endomyocardial fibrosis : pathological and molecular findings of surgically resected ventricular endomyocardium

Endomyocardial fibrosis (EMF) is a restrictive cardiomyopathy of unknown etiology prevalent in tropical regions affecting the inflow tract and apex of one or both ventricles, which show fibrous thickening of the endocardium and adjacent myocardium. Surgical treatment is recommended for patients in functional classes III or IV (New York Heart Association). The gross and histological features of the heart have been comprehensively studied in autopsies, but studies in surgical samples are still lacking. Histological and immunohistochemical features of EMF in surgical samples collected from 32 patients were described and correlated with clinical data. Polymerase chain reaction (PCR) and reverse transcription-PCR, performed on formalin fixed endomyocardial samples, were used retrospectively to detect genomes of certain cardiotropic viruses and Toxoplasma gondii. Ventricular endocardium was thickened by superficial acellular hyaline collagen fibers type I and III, with predominance of the former type. Besides fibrosis, a chronic inflammatory process and an anomalous lymphatic rich vascular pattern were observed in the deep endocardium, connected to the terminal coronary circulation of the myocardium, which might be an important pathological finding concerning EMF pathogenesis. Molecular analysis of the endomyocardium revealed high incidence of cardiotropic infective agents (6/12, 50%); however, their role in the disease pathogenesis is still controversial.

Intestinal spirochetosis: first cases reported in Brazil and the use of immunohistochemistry as an aid in histopathological diagnosis.

Colonization of the colon and rectum by intestinal spirochetes is detected for the first time in Brazil in 4 of 282 (1.41%) patients who had undergone sigmoidoscopy and/or colonoscopy with a histopathological diagnosis of chronic non specific-colitis. This frequency is probably underestimated, since surgically obtained specimens were not considered in the present study. Histopathological diagnosis was performed using routine stains like hematoxylin-eosin which showed the typical, of 3-microns thick hematoxyphilic fringe on the brush border of the surface epithelium, and by silver stains like the Warthin-Starry stain. Immunohistochemical procedures using two, polyclonal, primary antibodies, one against Treponema pallidum and the other against Leptospira interrogans serovar copenhageni serogroup Icterohaemorrhagiae cross-reacted with spirochetal antigen/s producing a marked contrast of the fringe over the colonic epithelium, preserving the spiral-shaped morphology of the parasite. In one case with marked diarrhea, immunohistochemistry detected spirochetal antigen/s within a cell in an intestinal crypt, thus demonstrating that the infection can be more widely disseminated than suspected using routine stains. Immunohistochemical procedures, thus, greatly facilitate the histological diagnosis of intestinal spirochetosis and may contribute to a better understanding of the pathogenesis of the disease. Transmission and scanning electron microscopy performed in one case showed that the spirochete closely resembled the species designated as Brachyspira aalborgi.

Human Hemorrhagic Pulmonary Leptospirosis: Pathological Findings and Pathophysiological Correlations

Background Leptospirosis is a re-emerging zoonosis with protean clinical manifestations. Recently, the importance of pulmonary hemorrhage as a lethal complication of this disease has been recognized. In the present study, five human necropsies of leptospirosis (Weil‘s syndrome) with extensive pulmonary manifestations were analysed, and the antibodies expressed in blood vessels and cells involved in ion and water transport were used, seeking to better understand the pathophysiology of the lung injury associated with this disease. Principal Findings Prominent vascular damage was present in the lung microcirculation, with decreased CD34 and preserved aquaporin 1 expression. At the periphery and even inside the extensive areas of edema and intraalveolar hemorrhage, enlarged, apparently hypertrophic type I pneumocytes (PI) were detected and interpreted as a non-specific attempt of clearence of the intraalveolar fluid, in which ionic transport, particularly of sodium, plays a predominant role, as suggested by the apparently increased ENaC and aquaporin 5 expression. Connexin 43 was present in most pneumocytes, and in the cytoplasm of the more preserved endothelial cells. The number of type II pneumocytes (PII) was slightly decreased when compared to normal lungs and those of patients with septicemia from other causes, a fact that may contribute to the progressively low PI count, resulting in deficient restoration after damage to the alveolar epithelial integrity and, consequently, a poor outcome of the pulmonary edema and hemorrhage. Conclusions Pathogenesis of lung injury in human leptospirosis was discussed, and the possibility of primary non-inflammatory vascular damage was considered, so far of undefinite etiopathogenesis, as the initial pathological manifestation of the disease.

MicroRNA Transcriptome Profiling in Heart of Trypanosoma cruzi-Infected Mice: Parasitological and Cardiological Outcomes

Chagas disease is caused by the parasite Trypanosoma cruzi, and it begins with a short acute phase characterized by high parasitemia followed by a life-long chronic phase with scarce parasitism. Cardiac involvement is the most prominent manifestation, as 30% of infected subjects will develop abnormal ventricular repolarization with myocarditis, fibrosis and cardiomyocyte hypertrophy by undefined mechanisms. Nevertheless, follow-up studies in chagasic patients, as well as studies with murine models, suggest that the intensity of clinical symptoms and pathophysiological events that occur during the acute phase of disease are associated with the severity of cardiac disease observed during the chronic phase. In the present study we investigated the role of microRNAs (miRNAs) in the disease progression in response to T. cruzi infection, as alterations in miRNA levels are known to be associated with many cardiovascular disorders. We screened 641 rodent miRNAs in heart samples of mice during an acute infection with the Colombiana T.cruzi strain and identified multiple miRNAs significantly altered upon infection. Seventeen miRNAs were found significantly deregulated in all three analyzed time points post infection. Among these, six miRNAs had their expression correlated with clinical parameters relevant to the disease, such as parasitemia and maximal heart rate-corrected QT (QTc) interval. Computational analyses identified that the gene targets for these six miRNAs were involved in networks and signaling pathways related to increased ventricular depolarization and repolarization times, important factors for QTc interval prolongation. The data presented here will guide further studies about the contribution of microRNAs to Chagas heart disease pathogenesis.

Stem cell apoptosis in HIV-1 alopecia.

Background:  Diffuse alopecia occurs in almost 7% of HIV‐1‐infected patients. Telogen effluvium is the main pathogenic mechanism involved. Apoptotic keratinocytes in the outer root sheath at bulge level was described as the most characteristic histopathologic finding of this kind of hair loss.

Schistosoma mansoni associated glomerulopathy

(1)Institute of Tropical Medicine, Sao Paulo, SP, Brasil. (2)Division of Nephrology, “Hospital das Clinicas”, University of S. Paulo, Medical School, S. Paulo, SP, Brasil. (3)Sao Paulo Federal University Medical School, Dept. of Microbiology, Immunology, and Parasitology, S. Paulo, SP, Brazil. Correspondence to: Dr. Thales De Brito, Av. Dr. Eneas de Carvalho Aguiar 470, 05403–000 S. Paulo, SP, Brazil. EMail: thalesbr@usp.br EDITORIAL

Role of p21 and oxidative stress on renal tubular resistance after acute ischaemic injury

BACKGROUND Subsequent ischaemic episodes may induce renal resistance. P21 is a cell cycle inhibitor that may be induced by oxygen-free radicals and may have a protective effect in ischaemic acute kidney injury (AKI). This study aimed at evaluating the role of oxidative stress and p21 on tubular resistance in a model of acquired resistance after renal ischaemia and in isolated renal tubules. METHODS Wistar rats were divided into: Group 1--sham; Group 2--sham operated and after 2 days submitted to 45-min ischaemia; and Group 3--45-min ischaemia followed after 2 days by a second 45-min ischaemia. Plasma urea was evaluated on Days 0, 2 and 4. Serum creatinine, creatinine clearance and oxidants (thiobarbituric acid-reactive substances) were determined 48 h after the second procedure (Day 4). Histology, immunohistochemistry for lymphocytes (CD3), macrophages (ED1), proliferation (PCNA) and apoptosis (TUNEL) were also evaluated. Rat proximal tubules (PTs) were isolated by collagenase digestion and Percoll gradient from control rats and rats previously subjected to 35 min of ischaemia. PTs were submitted to 15-min hypoxia followed by 45-min reoxygenation. Cell injury was assessed by lactate dehydrogenase release and hydroperoxide production (xylenol orange). RESULTS Ischaemia induced AKI in Group 2 and 3 rats. Subsequent ischaemia did not aggravate renal injury, demonstrating renal resistance (Group 3). Renal function recovery was similar in Group 2 and 3. Plasma and urine oxidants were similar among in Group 2 and 3. Histology disclosed acute tubular necrosis in Group 2 and 3. Lymphocyte infiltrates were similar among all groups whereas macrophages infiltrate was greater in Group 3. Cell proliferation was greater in Group 2 compared with Group 3. Apoptosis was similar in groups 2 and 3. The p21 expression was increased only in Group 3 whereas it was similar in groups 1 and 2. PTs from the ischaemia group were sensitive to hypoxia but resistant to reoxygenation injury which was followed by lower hydroperoxide production compared to control PT. CONCLUSION Renal resistance induced by ischaemia was associated with cell mechanism mediators involving oxidative stress and increased p21 expression.

Localization by Immunoelectron Microscopy of Schistosoma mansoni Antigens in the Glomerulus of the Hamster (Mesocricetus auratus) Kidney

Adult worm antigen (AWA) and soluble egg antigen (SEA) were localized ultrastructurally by immunoelectron microscopy using two monoclonal antibodies in the glomeruli of hamsters infected with Schistosoma mansoni cercariae or injected with S. mansoni eggs. AWA was detected in all cercaria-infected groups from the 30th day on and was present mainly in cytoplasm of mesangial cells, mesangial matrix, and glomerular basement membrane, either as isolated gold particles or in small electron-dense deposits of probable immune origin. AWA was encountered also on the inner side of the glomerular basal membrane, close to endothelial cells, and in the foot processes of the glomerular epithelial cells. SEA was detected at similar sites, apparently in lesser amounts, in uninfected hamsters inoculated with S. mansoni eggs into the jugular vein. Schistosomal antigens are apparently processed mainly by mesangial cells which are considered to be critical in the pathogenesis of S. mansoni associated glomerulopathy. Mesangioproliferative glomerulonephritis, immunoglobulin (IgG and IgM), and C3 deposits were observed in hamsters in which AWA and SEA were visualized. During early phases of the infection and in hamsters in which granulomatous pneumonitis was induced by S. mansoni eggs, glomeruli were unchanged or showed a slight mesangial proliferation. Our findings suggests that egg antigens also contribute to the pathogenesis of experimental glomerulopathy in the hamster.