Lymphocyte Populations in the Adventitial Layer of Hydatid Cysts in Cattle: Relationship With Cyst Fertility Status and Fasciola Hepatica Co-Infection.

Cystic echinococcosis is a worldwide zoonosis caused by the cestode Echinococcus granulosus. Two types of hydatid cysts occur in intermediate hosts: fertile cysts that generate protoscoleces from the germinal layer of the cyst, and infertile cysts that do not produce protoscoleces and are unable to continue the life cycle of the parasite. The adventitial layer, a host-derived fibrous capsule surrounding the hydatid cyst, is suggested to play an important role in local immune regulation during infection and in fertility of the cysts. Fasciola hepatica, another important parasite of cattle, induces a characteristic Th2-like immune response that could modulate the immune response against E. granulosus. Natural co-infection of both parasites is common in cattle, but no reports describe the local immune response against E. granulosus with F. hepatica infection in the same host. This study analyzed the number and distribution of T and B cells in the adventitial layer of liver and lung cysts and the relationship with cyst fertility and F. hepatica co-infection. T lymphocytes were the predominant cell type in the adventitial layer of infertile hydatid cysts and were more numerous in infertile hydatid cysts. B lymphocyte numbers were not associated with hydatid cyst fertility. Mast cells were infrequent in the adventitial layer. The number of T and B cells was not associated with F. hepatica co-infection. The present study contributes to the understanding of local immune responses in bovine cystic echinococcosis.

Therapeutic implications of NK cell regulation of allogeneic CD8 T cell-mediated immune responses stimulated through the direct pathway of antigen presentation in transplantation.

Natural killer (NK) cells are a population of innate type I lymphoid cells essential for early anti-viral responses and are known to modulate the course of humoral and cellular-mediated T cell responses. We assessed the role of NK cells in allogeneic CD8 T cell-mediated responses in an immunocompetent mouse model across an MHC class I histocompatibility barrier to determine its impact in therapeutic clinical interventions with polyclonal or monoclonal antibodies (mAbs) targeting lymphoid cells in transplantation. The administration of an NK cell depleting antibody to either CD8 T cell replete or CD8 T cell-depleted naïve C57BL/6 immunocompetent mice accelerated graft rejection. This accelerated rejection response was associated with an in vivo increased cytotoxic activity of CD8 T cells against bm1 allogeneic hematopoietic cells and bm1 skin allografts. These findings show that NK cells were implicated in the control host anti-donor cytotoxic responses, likely by competing for common cell growth factors in both CD8 T cell replete and CD8 T cell-depleted mice, the latter reconstituting in response to lymphopenia. Our data calls for precaution in solid organ transplantation under tolerogenic protocols involving extensive depletion of lymphocytes. These pharmacological biologics with depleting properties over NK cells may accelerate graft rejection and promote aggressive CD8 T cell cytotoxic alloresponses refractory to current immunosuppression.

Macrophage Subsets Within Granulomatous Intestinal Lesions in Bovine Paratuberculosis.

Animals infected with Mycobacterium avium subspecies paratuberculosis show a variety of granulomatous lesions that range from focal forms, seen in the subclinical stages, to diffuse lesions associated with clinical signs. The aim of this study was to phenotypically characterize the macrophages present in the different lesion types using immunohistochemical methods. Lesions from a total of 23 animals with bovine paratuberculosis, natural and experimental, were examined by immunohistochemistry. Antibodies against inducible nitric oxide synthase (iNOS), tumor necrosis factor α (TNF-α), CD163, interleukin 10 (IL-10), transforming growth factor ß (TGF-ß), major histocompatibility complex (MHC) class II, natural resistance-associated macrophage protein 1 (Nramp-1), calprotectin, Ki-67, CD68, lysozyme, and ionized calcium-binding adaptor molecule 1 (Iba-1) molecules were employed. Samples were scored semiquantitatively using a complete histological score (H-score), reflecting the staining intensity and the percentage of immunolabeled macrophages. Differences in the H-score were seen depending on the lesion type. In focal lesions, with none or few acid-fast bacilli (AFB), macrophages were polarized toward M1 phenotype, with high H-scores for iNOS and TNF-α. Diffuse multibacillary lesions showed M2 differentiation, with high expression of CD163, IL-10, and TGF-ß as well as Nramp-1 and MHC class II antigens. Macrophages in diffuse paucibacillary forms showed high H-scores for iNOS but low ones for TNF-α. Diffuse lesions, either multibacillary or paucibacillary, showed high calprotectin and low Ki-67 expression, suggesting a progressive character, while focal forms, with low H-scores for these antigens, would be consistent with latency. Lysozyme and CD68 expression were related to the amount of AFB. H-score for Iba-1 antibody was similar among all types. The findings of this study provide insights into the polarization status of macrophages and lesion development in bovine paratuberculosis.

Coexistence of granulomatous enteric inflammation and neoplasia in an adult sheep.

A 7-year-old dairy sheep suffering from chronic loss of weight without diarrhea or anorexia was euthanized after failing to respond to any treatment (antibiotic and antiparasitic). The main findings at the necropsy of this animal were multifocal miliary nodules in several organs, mainly in the Peyer's patches of the small intestine, and a segmental thickening of the jejunal wall. Histologic examination of the samples taken at the necropsy showed a multifocal chronic granulomatous inflammation, with mineralization and caseous necrosis at the core of the larger granulomas and scarce intrahistiocytic acid-fast bacilli consistent with a disseminated digestive tuberculosis. Polymerase chain reaction and bacteriological culture from these samples confirmed Mycobacterium avium subsp avium to be the etiologic agent of this infection. Histologically, the cause of the segmental thickening of the jejunal wall was found to be a small intestine adenocarcinoma, which in some areas coexisted with the granulomatous lesion.

Pathological findings in young and adult sheep following experimental infection with 2 different doses of Mycobacterium avium subspecies paratuberculosis.

Mycobacterium avium subsp paratuberculosis (Map) is assumed to infect young ruminants; however, little is known concerning the possibility of adult animals becoming infected. An experimental infection was conducted to establish the effect of age and doses of Map on susceptibility to paratuberculosis in sheep. Sixteen of twenty-four 1.5-month-old Churra lambs and 23 of 30 adult ewes (from 2-11 years old) were orally challenged with an ovine field strain of Map. Thirteen ewes and 8 lambs were infected with a high dose (HD) and 10 adult sheep and 8 lambs with a low dose (LD) of Map. The remaining animals were unchallenged controls. Animals were euthanized at 110 to 120 and 210 to 220 days postinfection. Histological, bacteriological, and nested polymerase chain reaction (PCR) studies were conducted in samples of intestine and related lymphoid tissue (Peyer patches, lymph nodes). Animals were classified according to their lesions. The number of granulomas was counted in 3 tissue sections from each sample. Only the HD groups showed lesions associated with paratuberculosis (92.3% of ewes and 100% of lambs). Adults had lesions characterized by few small demarcated focal granulomas restricted to the lymphoid tissue, whereas granulomas were more numerous and larger, appearing in the lamina propria unrelated to lymphoid tissue, in the lambs. Only HD-infected lambs were positive to culture, whereas nested PCR also detected positive HD ewes and some LD animals. These results suggest that adult sheep can become infected by Map, as seen by the development of lesions, but they are focal and restricted to the lymphoid tissue.

Patterns of lesion and local host cellular immune response in natural cases of ovine maedi-visna.

This study investigates the nervous form of ovine maedi-visna by histological and immunohistochemical techniques. The aim was to study the lesion types and the local cellular immune response related to each lesion type, and the possible relationship between these parameters. Thirty-four Assaf ewes were studied, 29 of which had shown nervous signs. Microscopical lesion patterns were described according to location, extent and predominance of inflammatory cell type. Immunohistochemical labelling of T cells (CD3(+), CD4(+), CD8(+) and cells expressing the γδ form of the T-cell receptor), B cells and macrophages revealed clear differences between the lesion patterns. Two main lesion types were described. Lymphocytic lesions had areas of mild-moderate injury characterized by a predominance of infiltrating T cells. Histiocytic lesions were more severe and had extensive areas of malacia and dominant infiltration by macrophages and B cells. Each animal had a unique lesion pattern and these differences could be due to individual resistance to the progression of infection. The lymphocytic lesions appear to represent initial or latent phases of slow progression, in which the animal presents some natural resistance to the infection. The histiocytic pattern may reflect a poor immune response or a greater virulence of the viral strain.

Maedi-visna: the meningoencephalitis in naturally occurring cases.

Lesions were examined at different levels of the central nervous system (CNS) in 64 sheep with natural maedi-visna (MV) meningoencephalitis. All animals showed lesions in more than one of the CNS locations examined; the lesions in the cranial regions were periventricular, while those in the spinal cord affected the white matter funicles. Lesions were found particularly in the cerebellar peduncles (non-suppurative meningoencephalitis), followed by the corpus callosum, hippocampus and thoracic spinal cord. Vascular, infiltrative and malacic histopathological patterns were recognized. One pattern predominated in each section examined, although mixed forms occurred. Vascular lesions occurred with similar frequency at all CNS levels, but infiltrative and malacic lesions predominated at rostral and caudal levels, respectively. Cells consistent with macrophages and shown immunohistochemically to be associated with MV virus were seen in malacic and infiltrative lesions, at the periphery of damaged areas.

Pathological features in marine birds affected by the prestige's oil spill in the north of Spain.

A total of 2,465 seabirds, mainly common murres (Uria aalge), razorbills (Alca torda), and puffins (Fratercula arctica) that beached in the northwestern part of Spain after the "Prestige" oil spill on 19 November 2002 were examined by pathological methods. Birds were divided into three groups: dead birds with the body covered (group 1) or uncovered (group 2) by oil and birds recovered alive but which died after being treated at a rescue center (group 3). The main gross lesions were severe dehydration and emaciation. Microscopically, hemosiderin deposits, related to cachexia and/or hemolytic anemia, were observed in those birds harboring oil in the intestine. Severe aspergillosis and ulcers in the ventriculus were found only in group 3 birds, probably because of stress associated with attempted rehabilitation at the rescue center. The mild character of the pathological changes suggests that petroleum oil toxicosis causes multiple sublethal changes that have an effect on the ability of the birds to survive at sea, especially weak and young, inexperienced animals. Dehydration and exhaustion seem to be the most likely cause of death.

Histopathological classification of lesions associated with natural paratuberculosis infection in cattle.

Paratuberculosis-associated lesions in 116 naturally infected adult cows, with or without clinical signs, were classified histopathologically. Tissue samples obtained focused on gut-associated lymphoid tissue. Lesions were divided into five categories. Focal lesions (n=68 cases), consisted of small granulomas in the ileal and jejunal lymph nodes or the ileocaecal lymphoid tissue. In the multifocal type (n=13 cases), small granulomas or scattered giant cells appeared in some intestinal villi, as well as in the lymph nodes. Diffuse multibacillary lesions (n=15 cases), associated with severe granulomatous enteritis affecting different intestinal locations and lymph nodes, were formed by macrophages containing large numbers of acid-fast bacilli. In diffuse lymphocytic lesions (n=3 cases), lymphocytes were the main inflammatory cells, with some macrophages or giant cells containing few if any mycobacteria. In diffuse intermediate forms (n=17 cases), the infiltrate was formed by abundant lymphocytes and macrophages, and mycobacteria were present to varying degrees related to the number of macrophages. Clinical signs and gross lesions were mainly associated with diffuse forms. Thickening of the intestinal wall, which was the most common macroscopical finding, was related to the degree of submucosal change. Mycobacterium avium subsp. paratuberculosis was identified by culture or PCR in all cows with diffuse lesions, and in 55.5 and 37% of those with multifocal or focal forms, respectively. The importance of sampling the ileal and caudal jejunal lymph nodes to find histological lesions of paratuberculosis in cattle is emphasized.

Orbital meningioma with a granular cell component in a dog, with extracranial metastasis.

A meningioma with a significant component of granular cells is described in the left ocular orbit of a 5-year-old male Golden retriever dog that presented with exophthalmos. The neoplastic mass surrounded the optic nerve. Microscopically, the tumour was characterized by nests of large, round to polygonal cells, variable in size, with eccentric nuclei and abundant eosinophilic cytoplasm, containing PAS-positive granules. In focal areas, cells were smaller and occasionally formed whorl-like structures. Immunohistochemical analysis revealed that neoplastic cells reacted positively for vimentin and, with less intensity, for neuron specific enolase and S-100, whereas they were negative for glial fibrillary acidic protein and cytokeratins. Metastatic growths, formed by similar cells, were seen in the lung and heart.

Giant cell tumour of bone in a cat with extraskeletal metastases: pathological and immunohistochemical study.

A case of giant cell tumour of bone (GCTb) in the lung and in a subcutaneous mass located in the right flank, with a probable primary origin in the mid-diaphysis of the right tibia, was described in a 8-year-old female cat. Numerous multinucleated giant cells were homogeneously distributed among a population of ovoid or spindle-shaped mononuclear cells. All of them were positive for vimentin suggesting a mesenchymal origin. Spindle-shaped tumour cells resemble fibroblastic cells, showing collagen fibres in their vicinity. Ovoid mononuclear cells are similar to macrophages, with a cytoplasm rich in electron-dense lysosomes. Multinucleated giant cells appear morphologically similar to osteoclasts. These findings are supported for the positive reaction to tartrate-resistant acid phosphatase (TRAP) and lysozyme, encountered only in ovoid and multinucleated giant cells. No immunoreactivity against human oestrogen receptors was observed in the nuclei of any neoplastic cells.

Osteoma in the skull of a sheep.

An osteoma located in the frontal bone and nasal cavity is described in a 4-year-old dairy sheep with respiratory difficulty and progressive emaciation. The mass was hard, formed by bone, and caused compression of the ethmoidal labyrinth. Microscopically, the tumour was characterized by trabeculae of woven bone, frequently coexisting with lamellar bone composed of fine fibres, lined by osteoblasts and surrounded by a fibrous stroma. A severe chronic inflammation was seen in the nasal mucosa. Differential diagnosis is discussed, particularly in relation to ossifying fibroma.

Expression of cytokeratins and vimentin in normal and neoplastic tissue from the bovine female reproductive tract.

The distribution of cytokeratins (CKs) and vimentin in the normal genital tract of calves and cows at different stages of the oestrous cycle and in epithelial tumours of the tract was studied immunohistochemically. Few differences in CK and vimentin immunolabelling were detected in relation to age or stage of the oestrous cycle. Coexpression of CKs in simple epithelia and in basal cells of stratified epithelia was detected in the oviduct and endocervix; this coexpression was different from that previously described in women. The demonstration of CKs but not vimentin in the neoplastic cells of a serous superficial ovarian papilloma suggested an origin from the ovarian surface epithelium, while the coexpression of CKs and vimentin in serous papillary and mucinous cystadenomas pointed to a possible origin from the rete ovarii. Studies on three uterine adenocarcinomas and the ovarian metastases from two of these showed an endometrial-CK phenotype. The intermediate filament profile of normal endometrium, conserved in uterine adenocarcinomas and their ovarian metastases, may be useful in discriminating between ovarian metastases from endometrial carcinomas and those originating from primary carcinomas in other organs.

Proximal aortic dissection (dissecting aortic aneurysm) in a mature ostrich.

The gross and histopathologic lesions observed in a case of spontaneous proximal aortic dissection (dissecting aortic aneurysm) in a mature ostrich are reported. At necropsy, a dissecting intramural hematoma was seen in the proximal aorta, extended about 12 cm distally from the aortic valves. Histopathologic changes in aortic dissection included fragmentation and disruption of elastic laminae, presence of cystic extracellular spaces, and pooling of ground substance in the tunica media. Hepatic copper levels were measured, and the low concentration found suggested that a copper deficiency together with other risk factors such as the elevation of blood pressure may have been implicated in the development of the aortic dissection seen in this ostrich.

Histopathological and immunohistochemical study of lambs experimentally infected with Fasciola hepatica and Schistosoma bovis.

The aim of this study was to investigate the cross-resistance between Fasciola hepatica and Schistosoma bovis in lambs assessing parasitologic, gross pathologic, histopathologic and immunohistochemical changes in liver and small intestine. Thirty Castellana breed lambs were divided into five comparable groups and exposed to F. hepatical S. bovis (group F/S), S. bovis/F. hepatica (group S/F), S. bovis (group S) or F. hepatica (group F) and six unexposed lambs were used as non-infected controls (group C). Primary patent infection with F. hepatica induced a lower number of schistosome eggs and a higher number of lymphocytes in intestinal and liver schistosome egg-induced granulomas in group F/S than in the groups S/F and S, liver damage being mainly attributed to F. hepatica. S. bovis infection followed by challenge with F. hepatica particularly increased the severity of the most significant liver alterations (cholangiohepatitis by F. hepatica and mesoendophlebitis by S. bovis) and F. hepatica seemed not to have an influence on established S. bovis infection. In addition, immunohistochemical results suggested that the predominant local immune response in both double-infected groups was different, being mainly a cell-mediated immune response in group F/S and a mucosal response in group S/F.