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.

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.

Extragenital cutaneous lesions of schistosomiasis mansoni: report of two cases.

Two cases of extragenital cutaneous lesions caused by eggs of Schistosoma mansoni are described. In one case the cutaneous involvement occurred during the acute phase of schistosomiasis; in the other the lesion appeared several years after specific treatment for schistosomiasis had been given.

Experimental production of EVI antibodies.

The production of an antibody which reacts with endocardium, blood vessels, and cardiac interstitial tissue (EVI factor) was experimentally obtained in rabbits immunized either with heterologous heart crude antigen, Trypanosoma cruzi antigen, a mixture of heart and T. cruzi antigens, kidney antigen or lung antigen, and complete Freund's adjuvant. Immunization lasted 2 months, with multiple subcutaneous and foot pad injections being made every 15th day. Preimmunization serum from each animal was used as normal control serum. Rabbit sera were tested by indirect immunofluorescence against mouse heart and skeletal muscle unfixed cryostat sections and revealed by fluoresceinated anti-rabbit globulin diluted 1:80. The highest titers appeared with anti-heart sera (1:192) and with anti-heart/T. cruzi sera (1:96). Incorporation of T. cruzi antigen in heart extract did not increase EVI antibody titers. It is suggested that the EVI factor is an antibody to many antigenic determinants, the majority of which are present in the heart and some of which cross-react with T. cruzi.

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.

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.

Comparative distribution of eosinophils in bone marrow, blood and peritoneal cavity in murine schistosomiasis.

Eosinophilia in murine schistosomiasis is very intense and extensive, involving distinct compartments such as bone marrow, blood, peritoneal cavity and tissues. Comparison of the shapes of eosinophil concentration or distribution curves showed a synchronization of the tendencies around 50% between blood and bone marrow, 33 to 64% between blood and peritoneal cavity, and 33 to 43% between peritoneal cavity and bone marrow. The hepatic eosinophil granulocytopoiesis or metaplasia follows the same pattern as observed in bone marrow. Schistosoma infection can be divided into three distinct phases based on the eosinophilic response: 1) non- or low-productive phase (before 35-40 days of infection), 2) acute productive phase (from 35-40 to 70-90 days), and 3) chronic productive phase (after 70-90 days of infection).

Eosinophils favor the passage of eggs to the intestinal lumen in schistosomiasis.

The release of Schistosoma mansoni eggs to the intestinal lumen of Swiss Webster albino mice is dependent on the peri-ovular inflammatory cells, especially eosinophils. The cells corrode the epithelial basal membrane and provide an easily penetrated environment for the eggs, allowing them to be passively expelled by intestinal peristalsis.

Intrinsic vascularization of granuloma in experimental paracoccidioidomycosis.

Rats infected with Paracoccidioides brasiliensis exhibited vascularized granulomas during the granulomatous stage, with more intensity on the 49th day after infection. These data change the classical belief that the granuloma is always an avascular structure. The authors suggest that the granuloma is under the balanced influence of angiogenic or angiostatic factors, with the usual predominance of the latter, with the consequent advantage of limited antigen diffusion to the vascular system.

Participation of endothelial cells in murine schistosomiasis.

The endothelial cells participate in the morphological events occurring during murine schistosomiasis, taking part in the development of hepatic periovular granuloma. The cells also show an increase in the expression of Factor VIII-related antigen in the portal vessels and hepatic sinusoids during the infection. Endothelial cells are suggested to play an important role in the pathogenesis of the disease and in the balance of the coagulant-anticoagulant mechanisms which favor the intravascular survival of the parasites.

Pancreatic involvement in murine schistosomiasis.

Pancreatic involvement during murine schistosomiasis is frequent (30 to 80%), heterogeneous, usually mild, but can occasionally be severe, characterized by granulomatous pancreatitis. After infection, pancreatic granulomas appear from day 50 on, with the most severe pancreatitis being demonstrable between days 90 and 100. Mice thus appear to be a useful model for study of the pathogenesis of Schistosoma mansoni-induced pancreatitis.

Fibrosis patterns of lesions developed by athymic and euthymic mice infected with Paracoccidioides brasiliensis.

Athymic and euthymic mice with BALB/c background were used to study the patterns of fibrosis during ip infection with a virulent isolate of Paracoccidioides brasiliensis. Specimens from various organs were collected from the animals at 1, 4 and 7 weeks after infection and observed under light microscopy using various histologic staining methods. Lesions from the first week of infection, in both animal groups, presented a predominance of collagen III over I, carboxylated proteoglycans, and a tendency to encapsulation. From 4 weeks onward, the lesions of nu/+ mice tended to involute to macrophage-pseudoxanthomatous aggregates or to encapsulation with an increase of collagen I and sulfated proteoglycans. On the contrary, with the evolution of the infection, the nu/nu mice displayed permanently active lesions, rich in reticular fibers and carboxylated proteoglycans, with varied amounts of collagens III and I, without or with minimal encapsulation. However, independent of the type of mice, or of the type of lesions, the minimal P. brasiliensis-ECM unit was formed by a fibrillar cocoon of reticular fibers that encloses an individual yeast or a "family" composed of a mother cell plus one or various peripheral daughter cells, alone or engulfed by macrophages or giant cells. The overall difference of the lesions of nude and normal mice was not in isolated aspects of their components, but in the general architecture of the lesions. Those of nu/+ mice were either of involutive or of encapsulated type (slightly active), and those of nu/nu mice were of the sustained-expansive type (very active), without or with minimal encapsulation.

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.

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.

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.

Clinical and epidemiological aspects of abdominal angiostrongyliasis in southern Brazil.

Most of the cases of abdominal angiostrongyliasis in Brazil were reported from the southern States of São Paulo, Paraná, Santa Catarina and Rio Grande do Sul (RS). A study in 27 cases from RS revealed a distinct local epidemiology. Peasants were usually affected, either adults or children, from the mountainous areas in the north of the State. There was a seasonal increase in the number of cases, from late spring to autumn, that does not coincide with the rainy season. Besides the most common clinical features of abdominal pain, fever and eosinophilia in the leukogram, painful relapsing episodes were detected in some patients. The abdominal pain could be either localized or diffuse during the rapid evolution to a surgical abdominal condition, with a lethality of 7.4%. The use of a serological test and the greater awareness of physicians working in endemic areas is expected to improve the recognition of uncomplicated and benign courses of the disease. This study confirms the known clinical manifestations of abdominal angiostrongyliasis and demonstrates the diversity of its epidemiology.

Evaluation of the resistance to Schistosoma mansoni infection in Nectomys squamipes (Rodentia: Cricetidae), a natural host of infection in Brazil.

The development of resistance in three stages throughout an active infection (pre-ovular, acute and initial chronic stages) was studied, comparing the total number of adult worms recovered from the reinfected group and the control groups. It was shown that Nectomys squamipes was unable to develop resistance in the tested conditions and, on the other hand, reinfection in the pre-ovular period of the parasite led the rodent to present the phenomenonacilitation, with reduction of natural resistance and an increase in the parasite load. These results suggest the existence of other forms of immunity diverse from the concomitant immunity in the host-parasite relationship, according to the employed model.

[Sarasinula marginata (Semper, 1885) (Mollusca, Soleolifera) from Belo Horizonte (MG, Brasil) as a potential intermediate host of Angiostrongylus costaricensis Morera, Cespedes, 1971]. / Sarasinula marginata (Semper, 1885) (Mollusca, Soleolifera) de Belo Horizonte (MG, Brasil) como hospedeira intermediária potencial do Angiostrongylus costaricencis Morera & Céspedes, 1971.

Specimens of Sarasinula marginata were collected in kitchen and house gardens of Belo Horizonte, Minas Gerais. The susceptibility of these molluscs for Angiostrongylus costaricensis was tested by infecting 15 laboratory--reared slugs (F1). The positivity demonstrated was of 80.0%.

[The susceptibility of Planorbidae from the metropolitan area of Belo Horizonte, MG (Brazil) to Angiostrongylus costaricensis (Nematoda, Angiostrongylidae)]. / Suscetibilidade de planorbídeos da região metropolitana de Belo Horizonte, MG (Brasil) ao Angiostrongylus costaricensis (Nematoda, Angiostrongylidae).

Biomphalaria glabrata (control), B. tenagophila and B. straminea from our laboratory colonies iniciated with molluscs collected in the municipality of Belo Horizonte, MG (Brasil), were experimentally infected with first-stage larvae of Angiostrongylus costaricensis. The number of molluscs of each species exposed was 139, 77 and 149. About 25 days later, surviving molluscs were individually examined by artificial digestion. Of 87 B. glabrata examined, 62 (71.3%) were positive and between one and 61 third-stage larvae were found; of 42 B. tenagophila, 21 (50.0%) contained between one five third-stage larvae; and of 89 B. straminea, 69 (77.5%) presented between one and 72 third-stage larvae. The three molluscan species are susceptible to A. costaricensis infection, but B. glabrata and B. straminea are most suitable for maintaining the nematode cycle in laboratory.

[Identification of wild rodents as hosts of Angiostrongylus costaricencis in southern Brazil]. / Identificação de roedores silvestres como hospedeiros do Angiostrongylus costaricensis no sul do Brasil.

Increasing number of human cases of abdominal angiostrongyliasis has been diagnosed in the south of Brazil. The main definitive host of Angiostrongylus costaricensis in Central America is the cotton rat (Sigmodon hispidus) that does not occur in South America, except in the north of Colombia, Peru and Venezuela. Rodents were captured in the endemic area in Rio Grande do Sul (RS) and definitive hosts were identified for the first time in Brazil: Oryzomys nigripes and Oryzomys ratticeps. O. nigripes is a small wild rodent and it appears to be the main definitive host of A. costaricensis in the highlands of RS, Brazil's southernmost State.