Pathological aspects of bovine focal fibrogranulomatous proliferative panniculitis (Lechiguana)

Lechiguana is a disease of cattle caused by an interaction between Dermatobia hominis warble and the bacteria Manheimia granulomatis. It is characterized by subcutaneous swellings that grow rapidly and result in death after 3 to 8 months. The objective of this paper was to investigate some vascular and fibrogenic changes of the disease at different lesion stages by histochemical and immunohistochemical techniques. A peculiar histopathological aspect observed during a proliferative phase (before treatment) was the intense vasculitis, described as degenerative and fibro-proliferative, expressed by the oncogene p53, possibly caused by the presence of bacteria in close contact with enthotelial cells, along with dense accumulations of lymphoid cells around venules. The synthesis of collagen fibers during the development of Lechiguana lesions assume a structural aspect of star arrangement with fiber radiation centers that gradually interconnect to design the Extracellular Matrix (ECM) framework, seen by Confocal Laser Scanning Microscopy (CSLM). Angiogenesis was the most characteristic finding in both proliferative and regressive stages as seen by the immunohistochemical expression of cytoskeleton proteins and von Willebrand (Factor VIII-Related Antigen). Additionally, in all tissues samples, active ECM elements like Metalloproteinases (MMPs), Tissue Inhibitors Metalloproteinases (TIMP) and Fibronectin (FN) were mainly associated to vessels structures. The extraordinary regression of exuberant granulation tissue after treatment is undoubtedly associated to the maintenance of the vascular components observed during the regressive phase.

Comprehensive proteomic profiling of adult Angiostrongylus costaricensis, a human parasitic nematode

Angiostrongylus costaricensis is a nematode helminth that causes an intestinal acute inflammatory process known as abdominal angiostrongyliasis, which is a poorly understood human disease occurring in Latin America. Our aim was to study the proteomic profiles of adult parasites focusing on immunogenic proteins. Total cellular extracts from both genders showed similar 2-DE profiles, with 60% of all protein spots focused between pH 5-7 and presenting molecular masses from 20.1 to 66 kDa. A total of 53 different dominant proteins were identified in our dataset and were mainly associated with the following over-represented Gene Ontology Biological Process terms: "macromolecule metabolic process", "developmental process", "response to stress", and "biological regulation". Female and male immunoblots showed similar patterns of reactive proteins. Immunoreactive spots identified by MALDI-PSD were found to represent heat shock proteins, a putative abnormal DAuer Formation family member, and galectins. To date, very few biochemical analyses have focused on the nematode Angiostrongylus costaricensis. As such, our results contribute to a better understanding of its biology and the mechanisms underlying the host-parasite relationship associated with this species. Moreover, our findings represent a first step in the search for candidate proteins for diagnostic assays and the treatment of this parasitic infection.

Schistosomal‐derived lysophosphatidylcholine are involved in eosinophil activation and recruitment through Toll‐like receptor-2-dependent mechanisms

Parasite‐derived lipids may play important roles in host‐pathogen interactions and escape mechanisms. Herein, we evaluated the role of schistosomal‐derived lipids in Toll‐like receptor (TLR)-2 and eosinophil activation in Schistosoma mansoni infection. Mice lacking TLR2 exhibited reduced liver eosinophilic granuloma, compared with that of wild‐type animals, following S. mansoni infection. Decreased eosinophil accumulation and eosinophil lipid body (lipid droplet) formation, at least partially due to reduced production of eotaxin, interleukin (IL)‐5, and IL‐13 in S. mansoni-infected TLR2-/- mice, compared with the corresponding production in wild‐type mice, was noted. Although no differences were observed in survival rates during the acute schistosomal infection (up to 50 days), increased survival of TLR2-/- mice, compared with survival of wild‐type mice, was observed during the chronic phase of infection. Schistosomal lipid extract– and schistosomal‐derived lysophosphatidylcholine (lyso‐PC)-stimulated macrophages in vitro induced TLR2‐dependent NF‐kB activation and cytokine production. Furthermore, in vivo schistosomal lyso‐PC administration induced eosinophil recruitment and cytokine production, in a mechanism largely dependent on TLR2. Taken together, our results suggest that schistosomal‐derived lyso‐PC may participate in cytokine production and eosinophil activation through a TLR2‐dependent pathway in S. mansoni infection. Moreover, our results suggest that TLR2‐dependent inflammatory reaction, cytokine production, and eosinophil recruitment and activation may contribute to the pathogenesis and lethality in the chronic phase of infection.

The embryonic development of Schistosoma mansoni eggs: proposal for a new staging system

Schistosomiasis is a water-borne parasitic illness caused by neoophoran trematodes of the genus Schistosoma. Using classical histological techniques and whole-mount preparations, the present work describes the embryonic development of Schistosoma mansoni eggs in the murine host and compares it with eggs maintained under in vitro conditions. Two pre-embryonic stages occur inside the female worm: the prezygotic stage is characterized by the release of mature oocytes from the female ovary until its fertilization. The zygotic stage encompasses the migration of the zygote through the ootype, where the eggshell is formed, to the uterus. Fully formed eggs are laid still undeveloped, without having suffered any cleavage. In the outside environment, eight embryonic stages can be defined: stage 1 refers to early cleavages and the beginning of yolk fusion. Stage 2 represents late cleavage, with the formation of a stereoblastula and the onset of outer envelope differentiation. Stage 3 is defined by the elongation of the embryonic primordium and the onset of inner envelope formation. At stage 4, the first organ primordia arise. During stages 5 to 7, tissue and organ differentiation occurs (neural mass, epidermis, terebratorium, musculature, and miracidial glands). Stage 7 is characterized by the nuclear condensation of neurons of the central neural mass. Stage 8 refers to the fully formed larva, presenting muscular contraction, cilia, and flame-cell beating. This staging system was compared to a previous classification and could underlie further studies on egg histoproteomics (morphological localizome). The differentiation of embryonic structures and their probable roles in granulomatogenesis are discussed herein.

First record of molluscs naturally infected with Angiostrongylus cantonensis (Chen, 1935) (Nematoda: Metastrongylidae) in Brazil

Seeking the identification of Angiostrongylus cantonensis as a potential etiological agent of three clinical cases of eosinophilic meningitis, mollusc specimens were collected in the state of Espírito Santo, Brazil. The snails were identified as Sarasinula marginata (45 specimens), Subulina octona (157), Achatina fulica (45) and Bradybaena similaris (23). Larvae obtained were submitted to polymerase chain reaction and restriction fragment length polymorphism diagnosis. Their genetic profile were corresponded to A. cantonensis. Rattus norvegicus experimentally infected with third-stage larvae, developed menigoencephalitis, and parasites became sexually mature in the lungs. Additionally, larvae obtained from A. fulica snails, from São Vicente, state of São Paulo, also showed genetic profiles of this nematode. This is the first record of Brazilian molluscs infected with this nematode species.

Development of Angiostrongylus costaricensis Morera and Céspedes 1971 (Nematoda: Angiostrongylidae) larvae in the intermediate host Sarasinula marginata (Semper 1885) (Mollusca: Soleolifera)

In life cycle of Angiostrongylus costaricensis, veronicellidae mollusks participate as the invertebrate host while rodents as the main vertebrate host. The current work shows a sequential larval development of A. costaricensis in Sarasinula marginata, individually killed and digested from day 1 to 43, post infection. Some larvae, recovered from sedimentation, were submitted to selective staining after paraffin embedded or inclusion in JB-4 to study inner structures. As control, four slugs were used, two killed at the beginning of infection and the others at the end of the experiment. At day 2 post infection, larvae were motionless and thick, presenting initial retention of granules. At day 4, L2 were detected, persisting until 43 days post infection. Larvae L2 displayed a large amount of granules rich in lipids and carbohydrates through its overall body, with more accumulation at the medial third corresponding to the esophagus-intestine transition site. Lipid granules, the main energetic source, were located at the basal and apical regions of intestinal cells. Both L1 and L3 presented bilateral alae, which is also common in other nematodes. Transition forms between L2 to L3 molts were also observed.

A new miracidia hatching device for diagnosing schistosomiasis

It is still imperative to develop a parasitological technique highly sensitive for diagnosing schistosomiasis in epidemiological and individual surveys. A simple and cheap hatching device with a collecting container was manufactured and tested under experimental conditions. Twelve Kato-Katz slides were performed as golden standard for comparison. Quantitative results can be carried out by counting miracidia in a plate and parasite load can be calculated (miracidia/gram of feces). Statistically significant values were higher in the hatching test. More sensitive results, with statistical significance, were achieved using 1.5 g of feces (which corresponds to 36 Kato-Katz slides) than by using the Kato-Katz method. Advantages of this technique and its limitations are presented.

Improved protein identification efficiency by mass spectrometry using N-terminal chemical derivatization of peptides from Angiostrongylus costaricensis, a nematode with unknown genome

Matrix-assisted laser desorption ionization (MALDI), Peptide Mass Fingerprinting (PMF) and MALDI-MS/MS ion search (using MASCOT) have become the preferred methods for high-throughput identification of proteins. Unfortunately, PMF can be ambiguous, mainly when the genome of the organism under investigation is unknown and the quality of spectra generated is poor and does not allow confident identification. The post-source decay (PSD) fragmentation of singly charged tryptic peptide ions generated by MALDI-TOF/TOF typically results in low fragmentation efficiency and/or complex spectra, including backbone fragmentation ions (series b and y), internal fragmentation etc. Interpreting these data either manually and/or using de novo sequencing software can frequently be a challenge. To overcome this limitation when studying the proteome of adult Angiostrongylus costaricensis, a nematode with unknown genome, we have used chemical N-terminal derivatization of the tryptic peptides with 4-sulfophenyl isothiocyanate (SPITC) prior to MALDI-TOF/TOF MS. This methodology has recently been reported to enhance the quality of MALDI-TOF/TOF-PSD data, allowing the obtainment of complete sequence of most of the peptides and thus facilitating de novo peptide sequencing. Our approach, consisting of SPITC derivatization along with manual spectra interpretation and Blast analysis, was able to positively identify 76% of analyzed samples, whereas MASCOT analysis of derivatized samples, MASCOT analysis of nonderivatized samples and PMF of nonderivatized samples yielded only 35, 41 and 12% positive identifications, respectively. Moreover, de novo sequencing of SPITC modified peptides resulted in protein sequences not available in NCBInr database paving the way to the discovery of new protein molecules.

Improved protein identification efficiency by mass spectrometry using N-terminal chemical derivatization of peptides from Angiostrongylus costaricensis, a nematode with unknown genome

Matrix-assisted laser desorption ionization (MALDI), Peptide Mass Fingerprinting (PMF) and MALDI-MS/MS ion search (using MASCOT) have become the preferred methods for high-throughput identification of proteins. Unfortunately, PMF can be ambiguous, mainly when the genome of the organism under investigation is unknown and the quality of spectra generated is poor and does not allow confident identification. The post-source decay (PSD) fragmentation of singly charged tryptic peptide ions generated by MALDI-TOF/TOF typically results in low fragmentation efficiency and/or complex spectra, including backbone fragmentation ions (series b and y), internal fragmentation etc. Interpreting these data either manually and/or using de novo sequencing software can frequently be a challenge. To overcome this limitation when studying the proteome of adult Angiostrongylus costaricensis, a nematode with unknown genome, we have used chemical N-terminal derivatization of the tryptic peptides with 4-sulfophenyl isothiocyanate (SPITC) prior to MALDI-TOF/TOF MS. This methodology has recently been reported to enhance the quality of MALDI-TOF/TOF-PSD data, allowing the obtainment of complete sequence of most of the peptides and thus facilitating de novo peptide sequencing. Our approach, consisting of SPITC derivatization along with manual spectra interpretation and Blast analysis, was able to positively identify 76% of analyzed samples, whereas MASCOT analysis of derivatized samples, MASCOT analysis of nonderivatized samples and PMF of nonderivatized samples yielded only 35, 41 and 12% positive identifications, respectively. Moreover, de novo sequencing of SPITC modified peptides resulted in protein sequences not available in NCBInr database paving the way to the discovery of new protein molecules.

Freshwater sponge spicules: a new agent of ocular pathology

In a recent outbreak of human ocular injuries that occurred in the town of Araguatins, at the right bank of Araguaia river, state of Tocantins, Brazil, along the low water period of 2005, two patients (8 and 12-year-old boys) presented inferior adherent leukoma in the left eye (OS), and peripherical uveites, with snowbanking in the inferior pars plana. The third one (13-year-old girl) showed posterior uveites in OS, also with snowbanking. Histopathological analysis of lensectomy material from the three patients and vitrectomy from the last one revealed several silicious spicules (gemmoscleres) of the freshwater sponges Drulia uruguayensis and D. ctenosclera. This work brings material evidences, for the first time in the literature, that freshwater sponge spicules may be a surprising new etiological agent of ocular pathology.

Germinal center architecture disturbance during Plasmodium berghei ANKA infection in CBA mice

Background

Immune responses to malaria blood stage infection are in general defective, with the need for long-term exposure to the parasite to achieve immunity, and with the development of immunopathology states such as cerebral malaria in many cases. One of the potential reasons for the difficulty in developing protective immunity is the poor development of memory responses. In this paper, the potential association of cellular reactivity in lymphoid organs (spleen, lymph nodes and Peyer's patches) with immunity and pathology was evaluated during Plasmodium berghei ANKA infection in CBA mice.

Methods

CBA mice were infected with 1 × 10⁶ P. berghei ANKA-parasitized erythrocytes and killed on days 3, 6–8 and 10 of infection. The spleen, lymph nodes and Peyer's patches were collected, fixed in Carson's formalin, cut in 5 μm sections, mounted in glass slides, stained with Lennert's Giemsa and haematoxylin-eosin and analysed with bright-field microscopy.

Results

Early (day 3) strong activation of T cells in secondary lymphoid organs was observed and, on days 6–8 of infection, there was overwhelming activation of B cells, with loss of conventional germinal center architecture, intense centroblast activation, proliferation and apoptosis but little differentiation to centrocytes. In the spleen, the marginal zone disappeared and the limits between the disorganized germinal center and the red pulp were blurred. Intense plasmacytogenesis was observed in the T cell zone.

Conclusion

The observed alterations, especially the germinal center architecture disturbance (GCAD) with poor centrocyte differentiation, suggest that B cell responses during P. berghei ANKA infection in mice are defective, with potential impact on B cell memory responses.

Plasmodium berghei ANKA infection induces thymocyte apoptosis and thymocyte depletion in CBA mice

Immune responses to malaria infections are characterized by strong T and B cell activation, which, in addition of potentially causing immunopathology, are of poor efficacy against the infection. It is possible that the thymus is involved in the origin of immunopathological reactions and a target during malaria infections. This work was developed in an attempt to further clarify these points. We studied the sequential changes in the thymus of CBA mice infected with Plasmodium berghei ANKA, a model in which 60-90% of the infected animals develop cerebral malaria. During the acute phase of infection, different degrees of thymocyte apoptosis were recorded. (1) starry-sky pattern of diffuse apoptosis with maintenance of cortical-medullary structure; (2) intense apoptosis with cortical atrophy, with absence of large cells; (3) severe cortical thymocyte depletion, resulting in cortical-medullary inversion. In the latter, only residual clusters of small thymocytes were observed within the framework of epithelial cells. The intensity of thymus alterations could not be associated with the degree of parasitemia, the expression of clinical signs of cerebral malaria or intensity of brain lesions. The implications of these events for malaria immunity and pathology are discussed.

Cross-immunoreactivity between anti-potato apyrase antibodies and mammalian ATP diphosphohydrolases: potential use of the vegetal protein in experimental schistosomiasis

We have previously showed that Schistosoma mansoni ATP-diphosphohydrolase and Solanum tuberosum potato apyrase share epitopes and the vegetable protein has immunostimulatory properties. Here, it was verified the in situ cross-immunoreactivity between mice NTPDases and anti-potato apyrase antibodies produced in rabbits, using confocal microscopy. Liver samples were taken from Swiss Webster mouse 8 weeks after infection with S. mansoni cercariae, and anti-potato apyrase and TRITC-conjugated anti-rabbit IgG antibody were tested on cryostat sections. The results showed that S. mansoni egg ATP diphosphohydrolase isoforms, developed by anti-potato apyrase, are expressed in miracidial and egg structures, and not in granulomatous cells and hepatic structures (hepatocytes, bile ducts, and blood vessels). Therefore, purified potato apyrase when inoculated in rabbit generates polyclonal sera containing anti-apyrase antibodies that are capable of recognizing specifically S. mansoni ATP diphosphohydrolase epitopes, but not proteins from mammalian tissues, suggesting that autoantibodies are not induced during potato apyrase immunization. A phylogenetic tree obtained for the NTPDase family showed that potato apyrase had lower homology with mammalian NTPDases 1-4, 7, and 8. Further analysis of potato apyrase epitopes could implement their potential use in schistosomiasis experimental models.

Four whole-istic aspects of schistosome granuloma biology: fractal arrangement, internal regulation, autopoietic component and closure

This paper centers on some whole-istic organizational and functional aspects of hepatic Schistosoma mansoni granuloma, which is an extremely complex system. First, it structurally develops a collagenic topology, originated bidirectionally from an inward and outward assembly of growth units. Inward growth appears to be originated from myofibroblasts derived from small portal vessel around intravascular entrapped eggs, while outward growth arises from hepatic stellate cells. The auto-assembly of the growth units defines the three-dimensional scaffold of the schistosome granulomas. The granuloma surface irregularity and its border presented fractal dimension equal to 1.58. Second, it is internally regulated by intricate networks of immuneneuroendocrine stimuli orchestrated by leptin and leptin receptors, substance P and Vasoactive intestinal peptide. Third, it can reach the population of +/- 40,000 cells and presents an autopoietic component evidenced by internal proliferation (Ki-67+ Cells), and by expression of c-Kit+ Cells, leptin and leptin receptor (Ob-R), granulocyte-colony stimulating factor (G-CSF-R), and erythropoietin (Epo-R) receptors. Fourth, the granulomas cells are intimately connected by pan-cadherins, occludin and connexin-43, building a state of closing (granuloma closure). In conclusion, the granuloma is characterized by transitory stages in such a way that its organized structure emerges as a global property which is greater than the sum of actions of its individual cells and extracellular matrix components.

Expression of adhesion molecules in lungs of mice infected with Paracoccidioides brasiliensis conidia

In infected tissues, leukocyte recruitment is mediated by interactions between adhesion molecules, expressed on activated vascular endothelial cells, and ligands present on circulating cells. We evaluated the inflammatory response and the expression of cellular adhesion molecules (ICAM-1, VCAM-1, CD18, LFA-1 and Mac-1) in lungs of BALB/c mice infected with Paracoccidioides brasiliensis conidia. When compared with uninfected animals, infected mice had a significant increase in the inflammatory response during the first 4 days, peaking 2-3 days post-challenge, 40.3% vs. 0.0% and 41.8% vs. 0.7%, respectively. This inflammatory infiltrate was composed mainly of neutrophils and macrophages with a few eosinophils and lymphocytes. An increase in the intensity of immunofluorescence (IF) for ICAM-1 was also observed during days 1-4. ICAM-1 was present in bronchiolar epithelium, type II pneumocytes, and macrophages, as well as on vascular endothelium. The control animals presented ICAM-1 constitutively. In infected mice, VCAM-1 was only observed on vascular endothelium during the first 2 days, with some macrophages expressing this molecule throughout the study periods. CD18 and Mac-1 but not LFA-1 were expressed with a high intensity on neutrophils and macrophages present in the inflammatory infiltrate. In addition, we observed a significant decrease in Colony forming units (CFUs) after the first 2 days post-challenge. These findings suggest that during these early stages, up-regulation of ICAM-1, VCAM-1, CD18 and Mac-1 expression occurs, participating in the inflammatory process and as such, in the pathogenesis of paracoccidioidomycosis (PCM).

Effect of S-nitrosoglutathione (GSNO) added to the University of Wisconsin solution (UW): II) Functional response to cold preservation/reperfusion of rat liver

Livers cold preserved in University of Wisconsin (UW) solution followed by reperfusion suffer ischemia/reperfusion injuries. Microcirculation is the primary target of damage, characterized by sinusoidal perfusion failure due, mainly, to morphological changes of sinusoidal endothelial cells. Here, we demonstrated that the addition of S-nitrosoglutathione (GSNO) to the UW solution before cold storage, as a nitric oxide (NO) donor, attenuated hepatic injuries.Wistar adult rat livers were stored in UW solution (0 degrees C-48 hs) and then reperfused during 60 minutes using the Isolated Perfused Rat Model (IPRL). We assayed four GSNO concentration (50, 100, 250 and 500 mM). NO concentration was estimated calculating the amount of nitrite (NO2-) generated in the UW solution. Injuries during cold preservation were established measuring lactate dehydrogenase (LDH) released to the UW solution. Meanwhile, intrahepatic resistance (IR), LDH released to the perfusate, the effluent/perfusate ratio for K+, bile flow, liver glycogen content and sinusoidal endothelial cell morphology were studied after 1 hour of reperfusion in the IPRL system. In cold preserved livers without GSNO, glycogen content was dramatically reduced, IR increased markedly, LDH released was high, bile flow diminished and sinusoidal endothelial cells appeared rounded and detached from perisinusoidal matrix after reperfusion. The presence of 100 mM GSNO prevented the IR rise and LDH release, improved bile production and partially reduced endothelial cells damages. In conclusion, the addition of 100 mM GSNO to UW solution improved hemodynamic and function capacity of cold preserved/reperfused livers.

ATP diphosphohydrolase fromSchistosoma mansoniegg: characterization and immunocytochemical localization of a new antigen

The fact that theSchistosoma mansoniegg has two ATP diphosphohydrolase (EC 3.6.1.5) isoforms with different net charges and an identical molecular weight of 63000, identified by non-denaturing polyacrylamide gel electrophoresis and immunological cross-reactivity with potato apyrase antibodies, is shown. In soluble egg antigen (SEA), only the isoform with the lower net negative charge was detected and seemed to be the predominant species in this preparation. By confocal fluorescence microscopy, using anti-potato apyrase antibodies, theS. mansoniegg ATP diphosphohydrolase was detected on the external surface of miracidium and in von Lichtenberg's envelope. Intense fluorescence was also seen in the outer side of the egg-shell, entrapped by the surface microspines, suggesting that a soluble isoform is secreted. ATP diphosphohydrolase antigenicity was tested using the vegetable protein as antigen. The purified potato apyrase was recognized in Western blots by antibodies present in sera from experimentallyS. mansoni-infected mice. In addition, high levels of IgG anti-ATP diphosphohydrolase antibodies were detected by ELISA in the same sera. This work represents the first demonstration of antigenic properties ofS. mansoniATP diphosphohydrolase and immunological cross-reactivity between potato apyrase and sera from infected individuals.

The equine thymus microenvironment: a morphological and immunohistochemical analysis

We characterized herein the microarchitecture of the equine thymus along with post-natal development (6 months-->18 years). Thymuses showed an involutional process, beginning before the puberty and defined by five histological grades, which consider the progressive cortical thymocyte depletion, shrinkage and rearrangement of the epithelial network and increase in extracellular matrix (ECM). A second feature of the equine thymus was the presence of eosinopoiesis, erythropoiesis, mastocytopoiesis and plasmacytogenesis. Additionally, lymphatic vessels, full of lymphocytes, were particularly prominent. Distribution of ECM proteins was heterogeneous, being denser in the medulla, as well as basement membranes of capsule, septa and perivascular spaces, thus similar to the patterns seen in other mammals. In vitro, horse thymic nurse cells produce ECM proteins, which are relevant in thymocyte/epithelial cell interactions. In conclusion, the equine thymus presents morphological and involutional characteristics similar to other mammals, exhibiting particular features, as prominent non-lymphoid hematopoiesis and lymphatic vessels.

Molecular differentiation of Angiostrongylus costaricensis, A. cantonensis, and A. vasorum by polymerase chain reaction- restriction fragment length polymorphism

Angiostrongylus cantonensis, A. costaricensis, and A. vasorum are etiologic agents of human parasitic diseases. Their identification, at present, is only possible by examining the adult worm after a 40-day period following infection of vertebrate hosts with the third-stage larvae. In order to obtain a diagnostic tool to differentiate larvae and adult worm from the three referred species, polymerase chain reaction-restriction fragment length polymorphism was carried out. The rDNA second internal transcribed spacer (ITS2) and mtDNA cytochrome oxidase I regions were amplified, followed by digestion of fragments with the restriction enzymes RsaI, HapII, AluI, HaeIII, DdeI and ClaI. The enzymes RsaI and ClaI exhibited the most discriminating profiles for the differentiation of the regions COI of mtDNA and ITS2 of rDNA respectively. The methodology using such regions proved to be efficient for the specific differentiation of the three species of Angiostrongylus under study.

Kinetics of eosinophil and IgE-mast cell changes following infection with Angiostrongylus costaricensis in Wistar rats

Human abdominal angiostrongyliasis is a severe eosinophilic disease caused by Angiostrongylus costaricensis. Previous studies have demonstrated that wild rodents are critically involved as definitive hosts to this nematode in nature. In this study, we have evaluated the susceptibility of Wistar rats (Rattus norvegicus) to A. costaricensis infection. Kinetics of parasitological and pathological changes, including the number of adult worms recovered from mesenteric arteries, and of IgE, mast cell and eosinophil levels in several compartments have been assessed. The oral inoculation of third-stage larvae (L3) into adult Wistar rats led to a marked accumulation of worms in the branches of the mesenteric arteries 25 and 50 days post-inoculation. Intense bone marrow eosinophilia ranging from 7 to 50 days was accompanied by marked accumulation of eosinophils in the blood, peritoneal and bronchoalveolar spaces. Eosinophilic periarteritis, oedema and granuloma in the intestinal and lung tissues were also histologically evident. Total serum IgE and specific anti-parasite IgE peaked at 25 days post-infection, as measured by ELISA and by the passive cutaneous anaphylaxis test, respectively. At that time point, there was a drastic reduction in the number of intact mast cells in the peritoneal effluent. These findings indicate that Wistar rats are permissive to A. costaricensis infection. IgE-mast cell activation and massive tissue eosinophil infiltration are marked features in the process and are likely to play a crucial role in the immune-response evoked by this parasite.

Intestinal fibrovascular nodules caused by Schistosoma mansoni infection in Calomys callosus Rengger, 1830 (Rodentia: Cricetidae): a model of concomitant fibrosis and angiogenesis

Human schistosomiasis develops extensive and dense fibrosis in portal space, together with congested new blood vessels. This study demonstrates that Calomys callosus infected with Schistosoma mansoni also develops fibrovascular lesions, which are found in intestinal subserosa. Animals were percutaneously infected with 70 cercariae and necropsied at 42, 45, 55, 80, 90 and 160 days after infection. Intestinal sections were stained for brightfield, polarization microscopy, confocal laser scanning, transmission and scanning electron microscopies. Immunohistological analysis was also performed and some nodules were aseptically collected for cell culture. Numerous intestinal nodules, appearing from 55 up to 160 days after infection, were localized at the interface between external muscular layer and intestinal serosa, consisting of fibrovascular tissue forming a shell about central granuloma(s). Intranodular new vessels were derived from the vasculature of the external vascular layer and were positive for laminin, chondroitin-sulfate, smooth muscle alpha-actin and FVIII-RA. Fibroblastic cells and extracellular matrix components (collagens I, III and VI, fibronectin and tenascin) comprised the stroma. Intermixed with the fibroblasts and vessels there were variable number of eosinophils, macrophages and haemorrhagic foci. In conclusion, the nodules constitute an excellent and accessible model to study fibrogenesis and angiogenesis, dependent on S. mansoni eggs. The fibrogenic activity is fibroblastic and not myofibroblastic-dependent. The angiogenesis is so prominent that causes haemorrhagic ascites.

Cellular mechanisms involved in the increased contraction of portal veins from Schistosoma mansoni-infected mice

We previously reported that portal veins from mice infected with male Schistosoma mansoni exhibited an increased reactivity to 5-hydroxytryptamine (5-HT). Here, we extended our observations to mice infected by both male and female worms and we further investigated another constrictor agent and the mechanism(s) responsible for the enhanced maximal contraction ( E(max)). Bisexual infection increased the E(max) of 5-HT (from 0.66+/-0.06 mN.s to 1.56+/-0.38 mN.s), in a similar way to the unisexual (male) infection. Infection with male worms increased portal vein reactivity to acetylcholine, as revealed by a higher E(max) (1.03+/-0.2 mN.s) in relation to non-infected control animals ( E(max)= 0.54+/-0.08 mN.s). Sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase (SERCA) inhibition with 100 nM thapsigargin reduced the E(max) of 5-HT by 35% in both tissues, discharging a deficiency of SERCA pump in infected animals. In contrast, the number of voltage-dependent Ca(2+) channels (L-type) was higher in portal veins from infected than non-infected control mice. Inhibition of Ca(2+)-activated chloride channels (Cl(Ca)) with 10 micro M niflumic acid reduced the E(max) of 5-HT in portal veins more from infected than non-infected animals (remaining tension = 60.9+/-2.2% and 70.4+/-2.3%, respectively). Histopathological analysis revealed an increased content of collagen and elastin in portal veins from male S. mansoni-infected mice, compatible with an increased intraluminal pressure. In conclusion, male S. mansoni altered portal vein physiology, increasing the E(max) of two vasoconstrictors, possibly by increasing membrane depolarisation through a more effective opening of Cl(Ca) channels, with calcium entering through L-type Ca(2+) channels.

Experimental models of Schistosoma mansoni infection

Experimental models of Schistosoma mansoni infections in mammals have contributed greatly to our understanding of the pathology and pathogenesis of infection. We consider here hepatic and extrahepatic disease in models of acute and chronic infection. Experimental schistosome infections have also contributed more broadly to our understanding of granulomatous inflammation and our understanding of Th1 versus Th2 related inflammation and particularly to Th2-mediated fibrosis of the liver.

Indirect effects of oral tolerance to ovalbumin interfere with the immune responses triggered by Schistosoma mansoni eggs

The objective of the present study was to investigate whether the injection of a tolerated protein (indirect effects) affects the formation of granulomas around Schistosoma mansoni eggs trapped in the lungs after intravenous (iv) injection into normal (noninfected) C57BL/6 mice (6 animals per group). To induce oral tolerance to chicken egg ovalbumin a 1/5 dilution of egg white in water was offered ad libitum in a drinking bottle for 3 days. Control mice received water. After 7 days, control and experimental animals were injected iv with 2,000 S. mansoni eggs through a tail vein. In some mice of both groups the iv injection of eggs was immediately followed by intraperitoneal (ip) immunization with 10 micro g of dinitrophenylated conjugates of ovalbumin (DNP-Ova) emulsified in complete Freund's adjuvant (CFA) or only CFA; 18 days later, mice were bled and killed by ether inhalation. The lungs were fixed in formalin and embedded in paraffin. Serial sections of 5 m were stained with Giemsa, Gomori's silver reticulin and Sirius red (pH 10.2). Granuloma diameters were measured in histological sections previously stained with Gomori's reticulin. Anti-DNP and anti-soluble egg antigen (SEA) antibodies were analyzed by ELISA. In mice orally tolerant to ovalbumin the concomitant ip injection of DNP-Ova resulted in significantly lower anti-SEA antibodies (ELISA*: 1395 +/- 352 in non-tolerant and 462 +/- 146 in tolerant mice) and affected granuloma formation around eggs, significantly decreasing granuloma size (area: 22,260 +/- 2478 to 12,993 +/- 3242 m ). Active mechanisms triggered by injection of tolerated antigen (ovalbumin) reduce granuloma formation.

Quantitative and qualitative interferences of pentoxifillyne on hepatic Schistosoma mansoni granulomas: effects on extracellular matrix and eosinophil population

Mast cells and eosinophils actively participate in tissue repair and are prominent components of Schistosoma mansoni granulomas. Since pentoxifillyne (PTX) is an immunomodulatory and antifibrotic substance, we aimed to characterize, by morphological techniques, the effect of this drug on fibrosis developed inside murine hepatic schistosomal granulomatous reaction, beyond the quantification of eosinophil and mast cell populations. The drug (1 mg/100 g animal weight) was administrated from 35 to 90 days post-infection, when the animals were killed. The intragranulomatous interstitial collagen network was analyzed by confocal laser scanning microscopy, the number of eosinophils and mast cells was quantified and the results were validated by t-student test. Treatment did not interfere on the granuloma evolution but caused a significant decrease in the total and involutive number of hepatic granulomas (p = 0.01 and 0.001, respectively), and in the intragranulomatous accumulation of eosinophils (p = 0.0001). Otherwise, the number of mast cells was not significantly altered (p = 0.9); however, it was positively correlated with the number of granulomatous structures (r = 0.955). In conclusion, PTX does not affect development and collagen deposition in S. mansoni murine granuloma, but decreases the intragranulomatous eosinophil accumulation possibly due to its immunomodulatory capability, interfering in cellular recruitment and/or differentiation.

Morphological aspects of Schistosoma mansoni adult worms isolated from nourished and undernourished mice: a comparative analysis by confocal laser scanning microscopy

Malnutrition hampers the course of schistosomiasis mansoni infection just as normal growth of adult worms. A comparative morphometric study on adult specimens (male and female) recovered from undernourished (fed with a low protein diet - regional basic diet) and nourished (rodent commercial laboratory food, NUVILAB) white mice was performed. Tomographic images and morphometric analysis of the oral and ventral suckers, reproductive system and tegument were obtained by means of confocal laser scanning microscopy. Undernourished male specimens presented smaller morphometric values (length and width) of the reproductive system (first, third and last testicular lobes) and thickness of the tegument than controls. Besides that, it was demonstrated that the dorsal surface of the male worms bears large tubercles unevenly distributed, but kept grouped and flat. At the subtegumental region, vacuolated areas were detected. It was concluded that the inadequate nutritional status of the vertebrate host has a negative influence mainly in the reproductive system and topographical somatic development of male adult Schistosoma mansoni, inducing some alterations on the structure of the parasite.

Pathogenesis II: fungal responses to host responses: interaction of host cells with fungi

Most of our knowledge concerning the virulence determinants of pathogenic fungi comes from the infected host, mainly from animal models and more recently from in vitro studies with cell cultures. The fungi usually present intra- and/or extracellular host-parasite interfaces, with the parasitism phenomenon dependent on complementary surface molecules. Among living organisms, this has been characterized as a cohabitation event, where the fungus is able to recognize specific host tissues acting as an attractant, creating stable conditions for its survival. Several fungi pathogenic for humans and animals have evolved special strategies to deliver elements to their cellular targets that may be relevant to their pathogenicity. Most of these pathogens express surface factors that mediate binding to host cells either directly or indirectly, in the latter case binding to host adhesion components such as extracellular matrix (ECM) proteins, which act as 'interlinking' molecules. The entry of the pathogen into the host cell is initiated by fungal adherence to the cell surface, which generates an uptake signal that may induce its cytoplasmic internalization. Once this is accomplished, some fungi are able to alter the host cytoskeletal architecture, as manifested by a rearrangement of microtubule and microfilament proteins, and this can also induce epithelial host cells to become apoptotic. It is possible that fungal pathogens induce modulation of different host cell pathways in order to evade host defences and to foster their own proliferation. For a number of pathogens, the ability to bind ECM glycoproteins, the capability of internalization and the induction of apoptosis are considered important factors in virulence. Furthermore, specific recognition between fungal parasites and their host cell targets may be mediated by the interaction of carbohydrate-binding proteins, e.g., lectins on the surface of one type of cell, probably a parasite, that combine with complementary sugars on the surface of host-cell. These interactions supply precise models to study putative adhesins and receptor-containing molecules in the context of the fungus-host interface. The recognition of the host molecules by fungi such as Aspergillus fumigatus, Paracoccidioides brasiliensis and Histoplasma capsulatum, and their molecular mechanisms of adhesion and invasion, are reviewed in this paper.

Trypanosoma cruzi in the scent glands of Didelphis marsupialis: the kinetics of colonization

This study examined the dynamics of colonization of Trypanosoma cruzi in the scent glands of the opossum Didelphis marsupialis following direct inoculation with 10(5) epimastigotes of isolate G-49 (an opossum-derived strain). One, three, and five days, 1 month, and 1 year after inoculation, scent glands were fixed for analysis using brightfield and electron microscopies. One day after inoculation the parasites, mainly as epimastigotes, were randomly distributed into the lumen. From the third day on, the parasites still in the form of epimastigotes tended to concentrate closer to the epithelium. The flagellates reached the definitive distribution pattern on the fifth day, when they formed huge clusters deep into the foveae. In samples collected 1 month and 1 year after inoculation, the ratio of epimastigotes:trypomastigotes was 1:1, with epimastigotes predominating near the epithelium and trypomastigotes far from it. Our observations suggest that T. cruzi grows continuously in the scent glands and does not depend on adhesion to promote metacyclogenesis. Metacyclogenesis far from the epithelium seems to be an important selective advantage to both host and parasite, since it assures the elimination of the infective forms of the parasite when the host expels the glands' contents, which occurs in frightening situations or at times of stress. The morphological characteristics of infected and noninfected scent glands using transmission and scanning electron microscopies were also described.

Distinct patterns of microvasculature in the cutaneous lesions of leprosy

This work is an investigation on the microvasculature of the cutaneous infiltrates of leprosy with the immunohistochemical staining of endothelial cells in cutaneous biopsies. Anti-Factor VIII-related antigen antibody (anti-FVIII-ra) and Ulex Europaeus-1 lectin (UEA-1) binding were utilized as endothelial cell markers. Thirty-nine patients grouped according to the Ridley-Jopling classification (14 borderline tuberculoid, 18 borderline lepromatous, 6 lepromatous, and 1 indeterminate leprosy) were selected for this study. Two microvascular architectural patterns could be clearly distinguished: lepromatous lesions presented a dense and tortuous mesh of microvessels among the Mycobacterium leprae-glutted macrophages; whereas the microvessels in the tuberculoid lesions were restricted to the periphery of the granulomas and were not seen among the central epithelioid cells. We were able to distinguish three basic morphological kinds of infiltrate distribution related to the microvessels: micronodules, cords and macronodules. Intensifications of the FVIII-ra immunoreactivity and UEA-1 binding capacity were observed in the endothelial cells of microvessels involved by the inflammatory infiltrate. A distinct cytokine expression profile at the leprosy poles and the role of mast cells in angiogenesis were speculated as factors contributing to these distinct patterns. Growth of the lesion and systemic dissemination of M. leprae in the bipolar spectrum of leprosy may hypothetically be influenced by the vascular-infiltrate relationship. The detection of angiogenesis in the cutaneous lesions of leprosy may bring about alternate and/or additional strategies for leprosy treatment.

Plasmodium berghei: cerebral malaria in CBA mice is not clearly related to plasma TNF levels or intensity of histopathological changes

Plasmodium berghei ANKA infection in CBA/J mice leads to the development of cerebral malaria (CM) that kills 80-90% of the animals in 6-9 days. This model has been used to study the pathogenesis of CM, which is a major cause of morbidity and mortality in Plasmodium falciparum-infected individuals. The role of cytokines in the induction of CM in the murine model has been well documented, but most studies have been restricted to the peak of neurological manifestations. Here we used a sequential approach to compare mice that developed CM with those that developed no cerebral pathology. Animals were examined for systemic histopathological changes and plasma Tumor Necrosis Factor-alpha (TNF) levels. The objectives were (a) to further determine the importance of factors commonly associated with murine CM-such as elevated levels of TNF and the presence of hemorrhage and vascular plugging-by comparing mice at different stages of infection and/or with different outcomes following infection and (b) to examine the importance of systemic changes-course of parasitemia and histopathological alterations in brain, liver, and lungs-in the development of CM. The data suggest that (a) the clinical manifestation of CM appears to be associated with a wave of merozoite release on days 6-7, (b) murine CM does not present reliable histopathological indicators, (c) there is no topographic association between the occurrence of intravascular plugging and the hemorrhagic foci, (d) monocyte-monocyte and monocyte-endothelial cell adherence were the most expressive histopathological events and were not restricted to brain vessels, (e) blood levels of TNF are not indicative of the local tissue reaction, (f) adhesiveness of monocyte/endothelial cells fluctuate during infection and is dissociated from the lymphocyte homing to the liver, and (g) pulmonary megakaryocytosis (megakaryopoiesis?) is a late event in the lungs.

Cyclooxygenase-2-derived prostaglandin E2 and lipoxin A4 accelerate resolution of allergic edema in Angiostrongylus costaricensis-infected rats: relationship with concurrent eosinophilia

In noninfected rats, challenge with allergen following local IgE sensitization induced a pleurisy marked by intense protein exudation that plateaued from 30 min to 4 h after challenge, reducing thereafter. Infection of rats with Angiostrongylus costaricensis induced a 5-fold increase in blood eosinophil numbers by 25 days postinfection, whereas the numbers of eosinophils in the pleural cavity ranged from normal to a weak increase. In infected rats, identically sensitized, challenge with Ag induced a much shorter duration of pleural edema with complete resolution by 4 h, but no change in the early edema response. In parallel, infection increased the number of eosinophils recovered from the pleural cavity at 4 h, but not at 30 min, following allergen challenge. Pretreatment with IL-5 (100 IU/kg, i.v.) also increased eosinophil numbers in blood and, after allergen challenge, shortened the duration of the pleural edema and increased pleural eosinophil numbers. There were increases in the levels of both PGE2 and lipoxin A4 (LXA4) in pleural exudate. Selective cyclooxygenase (COX)-2 inhibitors, NS-398, meloxicam, and SC-236, did not alter pleural eosinophilia, but reversed the curtailment of the edema in either infected or IL-5-pretreated rats. Pretreatment of noninfected animals with the PGE analogue, misoprostol, or two stable LXA4 analogues did not alter the magnitude of pleural exudation response, but clearly shortened its duration. These results indicate that the early resolution of allergic pleural edema observed during A. costaricensis infection coincided with a selective local eosinophilia and seemed to be mediated by COX-2-derived PGE2 and LXA4.

Influence of the genetic background on the pattern of lesions developed by resistant and susceptible mice infected with Paracoccidioides brasiliensis

To compare the sequential evolution of lesions developed by resistant (A/Sn) and susceptible (B10.A) mice to Paracoccidioides brasiliensis infection we inoculated a virulent isolate of the fungus and collected the pancreas/peripancreatic omentum monthly (from 1 to 6 months) post infection. After fixation, tissue sections were stained by conventional methods for light microscopy to investigate the cellular composition, the extracellular matrix (ECM) patterns and the morphology of the yeasts in the lesions. In both strains, the fungal lesions were localized mostly in the omentum; a few lesions in the pancreatic parenchyma were observed, mostly in B10.A mice. In both strains, macrophages and plasmocytes were the predominant cells in all lesions, followed by neutrophils (PMN) and macrophages transformed into giant and epithelioid cells. Remarkable differences were observed between resistant and susceptible mice, specially related to the ECM structure of the granulomatous lesions. In A/Sn mice, from the 1st month on, the coexistence of two types of lesions was observed: one type showed a well-defined encapsulated nodule, constituted mainly of type I collagen. Neutrophils were abundant in areas of massive fungal destruction and few viable yeasts were observed. The other type showed residual characteristics, with sparse collagen deposits and presence of xantomatous-like macrophages, containing degenerated fungi. Such residual lesions predominated after the 2nd month and were the only type observed from the 4th month on, indicating the control of the infection. In B10.A mice, on the contrary, only one type of lesion was observed, showing less tendency to encapsulation and the formation of multiple small granulomatous foci, individualized by reticular type III collagen fibers. There were many plasmocytes in the periphery and large numbers of budding yeasts, with no evidence of fungal destruction. In the course of the infection the lesions progressively increased in number and size. Altogether, the comparative histopathological analysis demonstrates the influence of the genetic pattern of the host on the lesions developed by resistant and susceptible mice to P. brasiliensis infection.

Penetration sites and migratory routes of Angiostrongylus costaricensis in the experimental intermediate host (Sarasinula marginata)

The intermediate hosts of Angiostrongylus costaricensis are terrestrian molluscs, mostly of the family Veronicellidae. The present work aimed at clarifying more accurately the sites of penetration and the migratory routes of A. costaricensis in the tissue slugs and at verifying the pattern of the perilarval reaction at different times of infection. Slugs were individually infected with 5,000 L1, and killed from 30 min to 30 days after infection. From 30 min up to 2 hr after infection, L1 were found within the lumen of different segments of the digestive tube having their number diminished in more advanced times after exposition until complete disappearance. After 30 min of exposition, percutaneous infection occurred, simultaneously to oral infection. Perilarval reaction was observed from 2 hr of infection around larvae in fibromuscular layer, appearing later (after 6 hr) around larvae located in the viscera. A pre-granulomatous reaction was characterized by gradative concentration of amebocytes around larvae, evolving two well-organized granulomas. In this work we confirmed the simultaneous occurrence of oral and percutaneous infections. Perilarval reaction, when very well developed, defined typical granulomatous structure, including epithelioid cell transformation. The infection also caused a systemic mobilization of amebocytes and provoked amebocyte-endothelium interactions.

Collagen arrangement in hepatic granuloma in mice infected with Schistosoma mansoni: dependence on fiber radiation centers

The collagen structure of isolated and in situ liver granuloma from Swiss Webster mice infected with Schistosoma mansoni was sequentially and three-dimensionally analyzed during different times of infection (early acute, acute, transitional acute-chronic, and chronic phases) by laser scanning confocal microscopy and electron scanning variable vacuum microscopy. The initial granuloma structure is characterized by vascular collagen residues and by anchorage points (or fiber radiation centers), from where collagenous fibers are angularly shed and self-assembled. During the exudative-productive stage, the self-assembly of these fibers minimizes energy and mass through continuous tension and focal compression. The curvature or angles between collagen fibers probably depends on the fibroblastic or myofibroblastic organization of stress fibers. Gradually, the loose unstable lattice of the exudative-productive stage transforms into a highly packed and stable architecture as a result of progressive compactness. The three-dimensional architecture of granulomas provides increased tissue integrity, efficient distribution of soluble compounds and a haptotactic background to the cells.

Effects of schistosomal mansoni infection on Calomys callosus coelom-associated lymphomyeloid tissue (milky spots)

Calomys callosus Rengger, 1830 (Rodentia: Cricetidae) is a mouse-like South American wild rodent, which is permissive to Schistosoma mansoni infection. In this paper we studied the effect of schistosomal infection in C. callosus mesenteric and omental milky spots (MS), subsidiary foci of coelom-associated lymphomyeloid tissue (CALT), during the acute, transitional (acute to chronic), and chronic phases of the infection. MS were morphologically analyzed by histological methods, using brightfield and confocal laser scanning microscopies. The MS of infected animals were mainly of lymphomyelocytic (42 to 90 days) and lymphoplasmacytic (160 days of infection) types and showed frequent presence of lymphoid follicles with germinal centers, plasmacytogenesis and plasmacytosis, mastocytosis, megakaryopoiesis, erythropoiesis and less pronounced eosinopoiesis. These results indicate that MS are a preferential site of germinal-center-dependent and independent plasmacytogenesis, and a bone marrow-like organ, committed with various cellular lineages. The consequence of C. callosus MS reactivity for schistosomal infection is still unknown and is under investigation.

Morphological study of adult male worms of Schistosoma mansoni Sambon, 1907 by confocal laser scanning microscopy

Aiming to detail data obtained through brightfield microscopy (BM) on reproductive, excretory and digestive system, specimens of Schistosoma mansoni eight weeks old, were recovered from SW mice, stained with Langeron's carmine and analyzed under a confocal laser scanning microscope CLSM 410 (Carl Zeiss). The reproductive system presented a single and lobate testis, with intercommunications between the lobes without efferent duct. Supernumerary testicular lobe was amorphous and isolated from the normal ones. Collecting tubules (excretory ducts), followed by the excretory bladder, opening to the external media through the excretory pore, were observed at the posterior extremity of the body. In the digestive tract, a cecal swelling was noted at the junction that originates the single cecum. It was concluded that through confocal laser scanning microscopy, new interpretations of morphological structures of S. mansoni worms could be achieved, modifying adopted and current descriptions. The gonad consists of a single lobed testis, similar to that observed in some trematode species. Moreover, the same specimens can be observed either by BM or CLSM, considering that the latter causes only focal and limited damage in tissue structures.

Histoarchitecture of schistosomal granuloma development and involution: morphogenetic and biomechanical approaches

The authors present morphogenetic and biomechanical approaches on the concept of the Schistosoma mansoni granulomas, considering them as organoid structures that depend on cellular adhesion and sorting, forming rearrangement into hierarchical concentric layers, creating tension-dependent structures, aiming to acquire round form, since this is the minimal energy form, in which opposing forces pull in equally from all directions and are in balance. From the morphogenetic point of view, the granulomas function as little organs, presenting maturative and involutional stages in their development with final disappearance (pre-granulomatous stages, subdivided in: weakly and/or initial reactive and exudative; granulomatous stages: exudative-productive, productive and involutional). A model for the development of granulomas was suggested, according to the following stages: encapsulating, focal histolysis, fiber production, orientation and compacting and involution and disintegration. The authors concluded that schistosomal granuloma is not a tangled web of individual cells and fibers, but an organized structure composed by host and parasite components, which is not formed to attack the miracidia, but functions as an hybrid interface between two different phylogenetic beings.

Trypanosoma cruzi: compromise of reproductive system in acute murine infection

Infection of isolated organs of the reproductive system by Trypanosoma cruzi has been described since Chagas' disease was first studied. A detailed histopathological analysis of mice acutely infected with T. cruzi CL strain showed colonization of male (preputial glands and skin, penis, testicular albuginea, epididymis, vas deferens, seminal vesicles, prostate, coagulative, bulbo urethral and urethral glands) and female (vagina, uterus, oviduct, ovary, mesovary, clitoris and mammary glands) structures of the reproductive system. The results presented herein demonstrated invasion of epithelial cells, pronounced colonization of the epididymis and male genital adnexa, but absence of parasitism in penile corpora cavernosa.

Immunological system and Schistosoma mansoni: co-evolutionary immunobiology. What is the eosinophil role in parasite-host relationship?

Schistosomes, ancestors and recent species, have pervaded many hosts and several phylogenetic levels of immunity, causing an evolutionary pressure to eosinophil lineage expression and response. Schistosoma mansoni adult worms have capitalized on the apparent adversity of living within the mesenteric veins, using the dispersion of eggs and antigens to other tissues besides intestines to set a systemic activation of several haematopoietic lineages, specially eosinophils and monocytes/macrophages. This activation occurs in bone marrow, spleen, liver, lymph nodes, omental and mesenteric milky spots (activation of the old or primordial and recent or new lymphomyeloid tissue), increasing and making easy the migration of eosinophils, monocytes and other cells to the intestinal periovular granulomas. The exudative perigranulomatous stage of the periovular reaction, which present hystolitic characteristics, is then exploited by the parasites, to release the eggs into the intestinal lumen. The authors hypothesize here that eosinophils, which have a long phylogenic story, could participate in the parasite-host co-evolution, specially with S. mansoni, operating together with monocytes/macrophages, upon parasite transmission.

Systemic modulation of peripheral eosinophilia (air pouch model) in Schistosoma mansoni infection

Schistosoma mansoni infection induces in their hosts a marked and sustained eosinophilia, which is influenced or modulated by complex mechanisms, that vary according to the phase of infection. To address this phenomenon, we used the air pouch (AP) model in control and infected Swiss webster mice, analyzing the cellular, tissue response and local expression of adhesion molecules [CD18 (beta(2)-chain), CD44, ICAm-1 (CD54), L-selectin (CD62L), CD49d (alpha(4)-chain), LFA1 (CD11 alpha)]. Infected animals were studied at 3 (pre-oviposition phase), 7 (acute phase), and 14 (chronic phase) weeks after infection (5-6 mice/period of infection). Normal mice were age-matched. Results showed that after egg stimulation, compared with matched controls, the infected mice, at each point of infection, showed a lower eosinophil response in the acute (7 weeks) and chronic phase (14 weeks) of infection. However, when the infected mice were in pre-oviposition phase (3 weeks) their eosinophil response surpassed the control ones. In the AP wall of infected mice, a significant decrease in the expression of ICAM-1 and CD44 in fibroblastic-like cells and a reduction in the number of CD18 and CD11 alpha in migratory cells were observed. The other adhesion molecules were negative or weakly expressed. The results indicated that in the air pouch model, in S. mansoni-infected mice: (1) eosinophil response is strikingly down-regulated, during the acute ovular phase; (2) in the pre-oviposition phase, in contrast, it occurs an up-regulatory modulation of eosinophil response, in which the mechanisms are completely unknown; (3) in the chronic phase of the infection, the down modulation of eosinophil response is less pronounced; 4) Down-regulation of adhesion molecules, specially of ICAM-1 appear to be associated with the lower eosinophil response.

Increased reactivity to 5-hydroxytryptamine of portal veins from mice infected with Schistosoma mansoni

In chronic severe infection with Schistosoma mansoni, portal hypertension accompanied by anatomical changes of the portal vasculature can develop as a consequence of granulomatous response to eggs. Mice infected unisexually with male worms were used in the present study in order to investigate a direct effect of worms on the reactivity of their host portal vein. A higher reactivity in the presence of 5-hydroxytryptamine (5-HT), but not in the presence of KCl 100 mM solution, was observed in portal vein from infected mice compared to healthy mice. It was characterized by an increase in the maximal contraction and sensitivity to 5-HT. Blockade of NO-synthase with N omega-nitro-L-arginine methyl ester (L-NAME) induced a small increase in 5-HT potency in the portal vein from non-infected mice, but did not change the amplitude of the contractions. In portal veins from infected mice, preincubation with L-NAME did not affect the reactivity to 5-HT. Histological analysis indicated endothelial damage, subendothelial fibrous plaques, and focal areas of inflammatory infiltrates in the adventitial layer. As a conclusion, these results show that unisexual infection of mice with male S. mansoni increased the reactivity of the portal vein to 5-HT which seems to be only partially related to an alteration in the endothelial production of nitric oxide.

Trypanosoma cruzi: paninfectivity of CL strain during murine acute infection

A systematic study of the distribution of intracellular parasites in the organs and tissues of mice acutely infected (15 days) with the CL strain of Trypanosoma cruzi was performed. Almost all tissues and organs were parasitized with different intensities, including several epithelial cell types. In addition to striated, cardiac, and smooth muscles a very high parasitism of fat cells, pancreas, and genital adnexa was observed. A smaller number of parasites was found in all other structures studied except in highly vascularized structures such as in the penile corpora cavernosa, pulmonary and renal parenchyma, islets of Langerhans, hepatic sinusoids, and in atrial endothelium. This paper also shows, for the first time in the literature, the parasitism of milky spots, cornea epithelium, cornea stroma, retroorbital fibroblasts, seminal vesicles, and coagulative, Cowper's, urethral, preputial, sebaceous anal, and clitoris glands. The results indicated that CL strain is highly invasive, being able to infect cells derived from the three embryonic layers (ectoderm, mesoderm, and endoderm), suggesting that the paninfectivity may influence the outcome of immunological and pathological events.

Histopathological study of experimental and natural infections by Trypanosoma cruzi in Didelphis marsupialis

Didelphis marsupialis, the most important sylvatic reservoir of Trypanosoma cruzi, can also maintain in their anal scent glands the multiplicative forms only described in the intestinal tract of triatomine bugs. A study of 21 experimentally and 10 naturally infected opossums with T. cruzi was undertaken in order to establish the histopathological pattern under different conditions. Our results showed that the inflammation was predominantly lymphomacrophagic and more severe in the naturally infected animals but never as intense as those described in Chagas' disease or in other animal models. The parasitism in both groups was always mild with very scarce amastigote nests in the tissues. In the experimentally infected animals, the inflammation was directly related to the presence of amastigotes nests. Four 24 days-old animals, still in embryonic stage, showed multiple amastigotes nests and moderate inflammatory reactions, but even so they survived longer and presented less severe lesions than experimentally infected adult mice. Parasites were found in smooth, cardiac and/or predominantly striated muscles, as well as in nerve cells. Differing from the experimentally infected opossums parasitism in the naturally infected animals predominated in the heart, esophagus and stomach. Parasitism of the scent glands did not affect the histopathological pattern observed in extraglandular tissues.

Histopathology of paracoccidioidomycotic infection in athymic and euthymic mice: a sequential study

We report the comparative and sequential histologic analysis of lesions developed by Paracoccidioides brasiliensis-infected athymic and euthymic BALB/c mice, using conventional and specific stain to characterize the morphology of fungi and inflammatory cells as well as the extracellular matrix patterns. In both groups, neutrophils and macrophages were the predominant cells; macrophage transition to giant and epithelioid cells was observed. Degenerated fungi and fungal dust were associated with local neutropil infiltration and the presence of pseudoxantomatous macrophages. Paracoccidioides brasiliensis are always found within an extracellular matrix microenvironment. The main differences between lesions developed by nu/+ and nude (nu/nu) mice resided in the more pronounced encapsulating tendency in the former ones. In both groups of animals, lesions in several organs were associated with extensive hemopoiesis. At the first week of infection, there was evidence of fungal destruction and control of its proliferation in both mouse groups. At the fourth and seventh weeks, nu/+ mice maintained the control of the infection, as shown by the scarce numbers of budding yeast cells, while experimental nu/nu mice showed a tumor-like progression of the disease with a striking increase in fungal load in many organs (e.g., omental and mesenteric milky spots, lymph nodes, spleen), some of which present their structure replaced by granulomatous lesions.

Spectrum of morphologic changes of lymph nodes in HIV infection

Cervical lymph nodes biopsies from 31 HIV positive patients (with or without AIDS) were studied by histologic methods and immunohistochemistry (StreptABC staining of paraffin sections) to identify cellular and extracellular matrix components. The results were the following: (1) the biopsies were included in the stages of follicular hyperplasia without fragmentation FH-FF (4 cases); follicular hyperplasia with follicular fragmentation FH + FF (16 cases); follicular involution FI (6 cases) and diffuse pattern DP (5 cases); (2) the most important alteration was the germinal centers disruption due to follicle lysis, which began in the light zone; (3) there was coincidence between intrafollicular hemorrhages and segmental hyaline mycroangiopathy; (4) during the progression of the disease occurred; (a) an increase in the number of mast cells, CD68+ and Mac 387+ macrophages; (b) a diffuse augment of collagen III, elastic fibers, laminin, fibronectin and proteoglycans; (c) maintenance of Factor VIII-related antigens in the vascular endothelial cells, with decrease in the expression of Ulex-Europeus I lectin. Follicular hyperplasia (FH - FF or FH + FF) was the most common histologic pattern recognized in the lymph nodes of patients without AIDS and follicular involution and difuse pattern were seen in those who had AIDS. The results indicate that the lymph node biopsies may provide important information about the evolutive stage of the disease and its prognosis.

Acute and chronic human adenovirus pneumonia: cellular and extracellular matrix components

We present a comparative histopathological study of both acute and chronic human adenovirus pneumonia, with reference to the cellular and extracellular matrix components. Seventeen lungs from autopsied patients whose ages ranged from 2 to 60 months were studied. Adenovirus types 1, 2, 3, 5, and 7 were isolated from 15 patients with acute lung disease, and types 2 and 7 were isolated from the other two patients with chronic pulmonary illness. The results indicated the occurrence of two basic patterns of adenovirus interstitial pneumonia (1) classic pattern (acute), characterized by necrosis and degeneration and many type II pneumocytes with intranuclear inclusion bodies, which were positive for adenovirus DNA by in situ hybridization, and (2) proliferative or proliferative-productive pattern (chronic), which presented with diffuse pulmonary fibrosis and the interstitial proliferation of fibroblast-like cells, compatible with myofibroblasts (positive for vimentin and alpha smooth muscle actin), and increase in collagen types I and III, elastic fibers, and proteoglycans. Alveolar collapse appears to be an important pathogenetic mechanism in the development of this pattern.

Neutrophil oxidative metabolism and killing of P. brasiliensis after air pouch infection of susceptible and resistant mice

The oxidative burst of polymorphonuclear neutrophils (PMN) and their ability to inhibit Paracoccidioides brasiliensis growth was studied in susceptible (B10.A) and resistant (A/J) mice. The cells were obtained after subcutaneous inoculation in air pouches, yielding highly pure PMN preparations; the number of cells was similar for both strains at 24 h and five times higher in the resistant strain at 15 days. The oxidative metabolism of these PMN was evaluated by the luminol and lucigen-enhanced chemiluminescence upon stimulation with PMA or killed P. brasiliensis (Pb). At 24 h of infection PMN from both strains showed similar responses. However, at 15 days a great enhancement of the Pb-stimulated luminol-enhanced chemiluminescence was observed only in PMN from resistant mice. Such increase was markedly inhibited by the addition of catalase. Independent of the mouse strain or time of infection of lucigen-enhanced chemiluminescence showed the same intensity. The lucigen-enhanced chemiluminescence of PMN without stimuli from resistant mice did not change with the time of infection, however, after 15 days of infection a significantly lower chemiluminescence was detected with PMN from susceptible mice. At 15 days of infection the PMN from B10.A were unable to kill P. brasiliensis yeast cells in vitro. Because the lucigenin- and luminol-enhanced chemiluminescence detects, respectively, the O2- production and the myeloperoxidase/hydrogen peroxide halide system, the present data show parallels between deficiency in the production of oxygen-reactive species by PMN and lower fungicidal activity.

Coelom-associated lymphomyeloid tissue (milky spots): site of lymphoid and myelomonocytic cell generation

Pleural and peritoneal milky spots (MS) are small morphofunctional structures representing subsidiary foci of coelom-associated lymphomyeloid tissue (CALT). In this paper we studied the cellular composition of CALT in normal and Schistosoma mansoni-infected mice. In the healthy mouse, CALT is mainly composed of IgM (+) B cells and presents lower numbers of CD23 and CD45R (B220) B2 lymphocytes. When activated by the infection, it may show pronounced lymphocytosis, plasmocytogenesis (IgM > IgG > IgA > IgG2a > IgG1) and myelomonocytosis. The lymphocytes were mainly of the B1 type (double positive CD5/IgM), with smaller number of T cells (TCR alpha beta (+), TCR gamma delta (+), CD3 (+) and CD5 (+)) and conventional B2 cells (B220 (+), CD23 (+)). The myeloid compartment was composed of immature and mature cells of monocyte/macrophage, eosinophil, neutrophil and megakaryocytic lineages, especially in the omental milky spots. CALT is also a favorable microenvironment for LFA-1 (+) mast cells. Thus, CALT appears to be a mixed lymphoid organ, with secondary and/or primary lymphoid organ functions, being an important site of B1 cell generation, plasma cell maturation and extramedullar hematopoiesis. CALT operates as an interface between blood and lymphatic circulation and coelomic cavities, because locally or externally produced cells have easy and ready access to the pleural and peritoneal cavities. Furthermore, MS cells can escape into blood and lymphatic vessels, providing lymphocytes to other lymphoid organs and to the mucosa-associated lymphoid tissue.