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The present study aimed to describe and characterize the cellular components during the evolution of chronic granulomatous inflammation in the teleost fish pacus (P. mesopotamicus) induced by Bacillus Calmette-Guerin (BCG), using S-100, iNOS and cytokeratin antibodies. 50 fish (120±5.0 g) were anesthetized and 45 inoculated with 20 μL (40 mg/mL) (2.0 x 106 CFU/mg) and five inoculated with saline (0,65%) into muscle tissue in the laterodorsal region. To evaluate the inflammatory process, nine fish inoculated with BCG and one control were sampled in five periods: 3rd, 7th, 14th, 21st and 33rd days post-inoculation (DPI). Immunohistochemical examination showed that the marking with anti-S-100 protein and anti-iNOS antibodies was weak, with a diffuse pattern, between the third and seventh DPI. From the 14th to the 33rd day, the marking became stronger and marked the cytoplasm of the macrophages. Positivity for cytokeratin was initially observed in the 14th DPI, and the stronger immunostaining in the 33rd day, period in which the epithelioid cells were more evident and the granuloma was fully formed. Also after the 14th day, a certain degree of cellular organization was observed, due to the arrangement of the macrophages around the inoculated material, with little evidence of edema. The arrangement of the macrophages around the inoculum, the fibroblasts, the lymphocytes and, in most cases, the presence of melanomacrophages formed the granuloma and kept the inoculum isolated in the 33rd DPI. The present study suggested that the granulomatous experimental model using teleost fish P. mesopotamicus presented a similar response to those observed in mammals, confirming its importance for studies of chronic inflammatory reaction.

Summary The study objective was to make histological, histochemical and morphometric evaluations on the splenic Melanomacrophage centers (MMCs) of tilapias, Oreochromis niloticus (Linnaeus, 1758), that were subjected to chronic inflammation stimuli by implantation (IMP) of a glass coverslip in the subcutaneous tissue and through inoculation of the bacillus Calmette‐Guerin (BCG). Randomly distributed in four groups were 150 tilapias: IMP (n = 45); IMP+BCG (n = 45); BCG (n = 45); and control (n = 15). Nine fish per treatment and three control fish were sampled on days 3, 7, 14, 21 and 33. The results demonstrated that increased numbers and areas of these structures were related to the type of stimulus, and that these were greater for the specific response. The principal pigment component identified was hemosiderin. Results suggest that the intensity of the MMC response in O. niloticus depended on the type of inflammatory stimulus used, and that it was greater in fish inoculated with BCG, which induced a granulomatous inflammation when compared to the foreign body inflammatory response induced by the glass coverslips.

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Samples of different organs from intensively-reared Piaractus mesopotamicus were collected and processed using routine histological techniques in order to produce thin sections for staining with hematoxylin-eosin and with the Ziehl-Neelsen method. Through examination under an optical microscope, myxosporidians of the genera Henneguya sp. and Myxobolus sp. were identified, respectivelyin the gills and kidneys of P. mesopotamicus. Plasmodia with immature spores of Henneguya sp. were located along the secondary lamellae, with total length of 30.45±4.84µm and width of 3.52±0.33µm. Spores of Myxobolus sp. were located in the kidneys, with total length of 8.94±0.82µm and width of 5.59±0.39µm. Histopathological analysis of the gills showed plasmodia containing spores of Henneguya sp., at intralamellar and intravascular localities, at different stages of development. Spores of Myxobolus sp. were identified in the kidneys, in the peritubular region and in the interstices and glomerulus, surrounded by melanomacrophages. Focal hemorrhage was recorded in a few cases. Ziehl-Neelsen staining allowed to identify particular features of the spores and facilitated biometry and enabled classification in comparison with hematoxylin-eosin, thus demonstrating its usefulness for histopathological diagnosis of the parasitosis.

ABSTRACT:The aim of this study was to evaluate the effect of parenteral administration of dexamethasone and levamisole on the accumulation of macrophages and formation of giant cells in chronic inflammation by foreign body and blood parameters in pacu (Piaractus mesopotamicus). It was used 50 mg/kg of levamisole and 2.0 mg/kg of dexamethasone and the combination of both drugs. Coverslips were implanted under the skin. After 2, 7, and 15 days postimplantation (DPI), fish were anesthetized for removal of coverslips and the number of macrophages and giant cells were count. It was also collected blood from the caudal vessel to evaluate: red blood cell count, hematocrit, hemoglobin concentration, leukocytes count, thrombocytes count, MCV, and MCHC. We observed that dexamethasone affects negatively the formation of giant cells in the chronic inflammation for foreign body. Levamisole, despite being immunostimulatory in several species, showed limited action. However, it was enough to counteract the effect of dexamethasone; the association of the drugs did not interfere significantly in erythrocyte and leukocyte number in most of the treatments and times studied. In dexamethasone group there was a reduction in the number of erythrocytes and hemoglobin associated with increased mean corpuscular volume, suggesting slight macrocytic anemia. At 15 DPI, most groups showed the recovery of hematologic response. As in mammals, dexamethasone affects negatively the inflammatory response. Levamisole showed little effect by itself. However, in some parameters the association of both drugs causes similar response to control and naïve groups, showing the antagonistic effect of these drugs.

The aim of this study was to evaluate the effect of probiotic Bacillus amyloliquefaciens on the growth performance, blood profile and intestinal morphometry in Nile tilapia (Oreochromis niloticus) reared in cages. 936 Nile tilapias were distributed in 12 cages (1.5 m3). Fish were fed for 90 days on basal diets containing 0 (control); 1×106 CFU g-1; 5×106CFU g-1; and 1×107CFU g-1 of the probiotic. The results showed no significant difference on performance and proximal composition of fish. Blood glucose and hemoglobin were lower in 1×107 CFU g-1 group, suggesting improves of the homeostatic state of the fish. Other hematimetric indices did not differ between groups. It was observed significant increase of villi height and in the number of goblet cells of the intestine in fish supplemented 5×106 CFU g-1 and 1×107 CFU g-1 of food suggesting that fish improved the digestion and absorption of nutrients. However, more studies are needed to determine the efficacy of this probiotic in field conditions in Nile tilapia.

Objetive. This study was conducted to evaluate, by means of lectinhistochemistry (LHC), the expression of carbohydrates in granulomas induced by the bacillus Calmette-Guerin (BCG) in muscle tissue of Piaractus mesopotamicus after 33 days. Material and methods. Histological sections with 3 μm thick were incubated with the following lectins :WGA (Wheat germ agglutinin), DBA (Dolichos biflorus agglutinin) and HPA (Helix pomatia agglutinin), and the results were evaluated by light microscopy. Results. Acid fast bacilli were stained by Ziehl Neelsen (ZN) and strong labeled by WGA in the cytoplasm of macrophages. Labeling with DBA was intense in fibroblasts and weak in macrophages. On the other hand, HPA binding was stronger in macrophages, especially in those that were in close contact with epithelioid cells, without evidence of binding to fibroblasts. The epithelioid cells were not labeled by the used lectins, but they were identified by Hematoxilin-Eosin (HE). The lectins labeled specific type saccharides in glycoproteins, as N-acetylglucosamine present in bacilli and macrophages, as well as N-acetyl-galactosamine in macrophages. The control group showed no inflammation or lectin binding. Conclusions. This technique may be useful in identifying receptors for WGA, DBA and the HPA lectins in epithelioid granuloma induced by BCG in P. mesopotamicus