Judith Trujillo

Brain Granulomas in Neurocysticercosis Patients Are Associated with a Th1 and Th2 Profile

ABSTRACT Neurocysticercosis (NCC) is a common central nervous system (CNS) infection caused by Taenia solium metacestodes. Despite the well-documented importance of the granulomatous response in the pathogenesis of this infection, there is limited information about the types of cells and cytokines involved. In fact, there has been limited characterization of human brain granulomas with any infectious agent. In the present study a detailed histological and immunohistochemical analysis of the immune response was performed on eight craniotomy specimens where a granuloma surrounded each T. soliummetacestode. The results indicated that in all the specimens there was a dying parasite surrounded by a mature granuloma with associated fibrosis, angiogenesis, and an inflammatory infiltrate. The most abundant cell types were plasma cells, B and T lymphocytes, macrophages, and mast cells. Th1 cytokines were prevalent and included gamma interferon, interleukin-18 (IL-18), and the immunosuppressive, fibrosis-promoting cytokine transforming growth factor β. The Th2 cytokines IL-4, IL-13, and IL-10 were also present. These observations indicate that a chronic immune response is elicited in the CNS environment with multiple cell types that together secrete inflammatory and anti-inflammatory cytokines. In addition, both collagen type I and type III deposits were evident and could contribute to irreversible nervous tissue damage in NCC patients.

In vivo binding of the Cry11Bb toxin of Bacillus thuringiensis subsp. medellin to the midgut of mosquito larvae (Diptera: Culicidae)

Bacillus thuringiensis subsp. medellin produces numerous proteins among which 94 kDa known as Cry11Bb, has mosquitocidal activity. The mode of action of the Cry11 proteins has been described as similar to those of the Cry1 toxins, nevertheless, the mechanism of action is still not clear. In this study we investigated the in vivo binding of the Cry11Bb toxin to the midgut of the insect species Anopheles albimanus, Aedes aegypti, and Culex quinquefasciatus by immunohistochemical analysis. Spodoptera frugiperda was included as negative control. The Cry11Bb protein was detected on the apical microvilli of the midgut epithelial cells, mostly on the posterior midgut and gastric caeca of the three mosquito species. Additionally, the toxin was detected in the Malpighian tubules of An. albimanus, Ae. aegypti, Cx. quinquefasciatus, and in the basal membrane of the epithelial cells of Ae. aegypti midgut. No toxin accumulation was observed in the peritrophic membrane of any of the mosquito species studied. These results confirm that the primary site of action of the Cry11 toxins is the apical membrane of the midgut epithelial cells of mosquito larvae.

The human nervous tissue in proximity to granulomatous lesions induced by Taenia solium metacestodes displays an active response

In neurocysticercosis, the nervous tissue surrounding the brain lesion is affected as a consequence of the local immune response induced by a Taenia solium metacestode. In this study, a histological and immunohistochemical analysis of five brain specimens from patients with neurocysticercosis revealed a proinflammatory activity reflected by an apparently altered blood-brain barrier permeability, secretion of pro-inflammatory cytokines, and up-regulation of molecules associated with antigen presentation. There were also anti-inflammatory cytokines, as well as an active wound-healing process reflected by angiogenesis, collagen deposition and glial scar formation. This immune response displayed by the nervous tissue adjacent to chronic neurocysticercosis lesions appeared to be contributing to the local tissue damage, and hence, may be fundamental in the pathology of NCC.

Fibrotic sequelae in pulmonary paracoccidioidomycosis: histopathological aspects in BALB/c mice infected with viable and non-viable Paracoccidioides brasiliensis propagules

Patients with paracoccidioidomycosis often present pulmonary fibrosis and exhibit important respiratory limitations. Based on an already established animal model, the contribution of viable and non-viable P. brasiliensis propagules to the development of fibrosis was investigated. BALB/c male mice, 4-6 weeks old were inoculated intranasally either with 4x10(6) viable conidia (Group I), or 6. 5x10(6) fragmented yeast cells (Group II). Control animals received PBS. Six mice per period were sacrificed at 24, 48, 72h (initial) and 1, 2, 4, 8, 12 and 16 weeks post-challenge (late). Paraffin embedded lungs were sectioned and stained with H&E, trichromic (Masson), reticulin and Grocot&tacute;s. During the initial period PMNs influx was important in both groups and acute inflammation involving 34% to 45% of the lungs was noticed. Later on, mononuclear cells predominated. In group I, the inflammation progressed and granulomas were formed and by the 12th week they fussed and became loose. Thick collagen I fibers were observed in 66.6% and 83.3% of the animals at 8 and 12 weeks, respectively. Collagen III, thick fibers became apparent in some animals at 4 weeks and by 12 weeks, 83% of them exhibited alterations in the organization and thickness of these elements. In group II mice, this pattern was different with stepwise decrease in the number of inflammatory foci and lack of granulomas. Although initially most animals in this group had minor alterations in thin collagen I fibers, they disappeared by the 4th week. Results indicate that tissue response to fragmented yeast cells was transitory while viable conidia evoked a progressive inflammatory reaction leading to granuloma formation and to excess production and/or disarrangement of collagens I and III; the latter led to fibrosis.

Development of pulmonary fibrosis in mice during infection with Paracoccidioides brasiliensis conidia

Pulmonary fibrosis is a feared sequelae of paracoccidioidomycosis. We sought to determine if mice exposed to Paracoccidioides brasiliensis conidia would develop pulmonary fibrosis. BALB/c mice were infected intranasally with P. brasiliensis conidia and sacrificed at regular intervals. One lung was sectioned for histopathology and sections were stained with haematoxylin and eosin, trichromic and argentic stains; the other lung was homogenized and cultured to determine the viability of the fungus. One week post-challenge, only small peribronchial foci were apparent. After 4 weeks, reticular fibres appeared disorganized and disrupted. Six to 8 weeks later peribronchial infiltrates were larger and appeared surrounded by reticular fibres; thick collagen I fibres were noticed in the infiltrated areas at this time. On weeks 10-12, infiltrates were confluent and reticular fibres were concentrated around the inflammatory foci; collagenization was apparent. Observations up to 16 weeks revealed diffuse involvement of the lung parenchyma with extensive collagenization. Lung cultures were always positive. We suggest that inhalation of P. brasiliensis conidia induces adverse lung responses leading to changes in the proportion of collagen fibres I and III.

The inflammatory cell infiltrates in porcine cysticercosis: immunohistochemical analysis during various stages of infection.

Taenia solium metacestodes cause cysticercosis in both humans and pigs. In the former host species, the central nervous system involvement (neurocysticercosis (NCC)) may range from asymptomatic to life-threatening, but little is known about the corresponding variation in tissue response due to the difficulty in obtaining parasite-infected brain biopsies. The use of pigs as animal models for cysticercosis is ideal because the histological description of the animals response around the parasites resembles the one recorded in human specimens. In this study the histological features of the immune response in swine were complemented by immunohistochemical analysis to determine the phenotype of the inflammatory cells. The presence of mononuclear cells and eosinophils, and the co-localization of MHC-II with B lymphocytes and monocytes/macrophages within the granulomas surrounding the parasites, were features that closely resembled the descriptions made in prior studies with human specimens. In addition, there were novel findings such as the upregulation of the adhesin CD44 in cells resembling monocytes/macrophages, eosinophils and in astrocytes from the central nervous system. The upregulation of CD44 may be important for the recruitment of inflammatory cells to the site of the lesion. Finally, the presence of null-gamma delta-T cells since stage I of the immune response was similar to the early detection of these cells in mouse models for cysticercosis.

IN SITU DETECTION OF ANTIGENIC GLYCOPROTEINS IN TAENIA SOLIUM METACESTODES

Taenia solium has a complex life cycle. Its cysticercus can lodge in the brain, causing neurocysticercosis (NCC), and the adult tapeworms survival in the intestine results in taeniasis. In this study, the in situ detection of previously described glycoprotein antigens used for serological diagnosis of NCC and the detection of other glycoconjugates was explored in cysticerci and the surrounding porcine tissue to understand their potential role in pathogenesis. Immunohistochemistry with an antiserum specific for glycoprotein antigens rich in N-linked carbohydrates and in situ histochemistry with a battery of lectins that have affinity to a variety of glycoconjugates were performed. The glycoconjugates rich in N-linked carbohydrates were detected in the vesicular fluid and tegument of the vesicular membrane and scolex, where the parasite has direct contact with the host tissues during cysticercosis and taeniasis, respectively. Additionally, as the inflammatory response progressed, the parasites antigenic glycoproteins were also detected in the cytoplasm of inflammatory cells in the surrounding granuloma. In contrast, the spiral canal tegument, which will be exposed to intestinal enzymes in taeniasis, had N-acetyl-galactosamine–rich mucins. Thus, the differential saccharidic composition in T. solium metacestode structures may be important for the survival of the parasite in different host sites.