Restricted infection with canine distemper virus leads to down-regulation of myelin gene transcription in cultured oligodendrocytes

Transcriptional changes in canine distemper virus-induced demyelinating leukoencephalitis favor a biphasic mode of demyelination

Canine distemper virus (CDV)-induced demyelinating leukoencephalitis in dogs (Canis familiaris) is suggested to represent a naturally occurring translational model for subacute sclerosing panencephalitis and multiple sclerosis in humans. The aim of this study was a hypothesis-free microarray analysis of the transcriptional changes within cerebellar specimens of five cases of acute, six cases of subacute demyelinating, and three cases of chronic demyelinating and inflammatory CDV leukoencephalitis as compared to twelve non-infected control dogs. Frozen cerebellar specimens were used for analysis of histopathological changes including demyelination, transcriptional changes employing microarrays, and presence of CDV nucleoprotein RNA and protein using microarrays, RT-qPCR and immunohistochemistry. Microarray analysis revealed 780 differentially expressed probe sets. The dominating change was an up-regulation of genes related to the innate and the humoral immune response, and less distinct the cytotoxic T-cell-mediated immune response in all subtypes of CDV leukoencephalitis as compared to controls. Multiple myelin genes including myelin basic protein and proteolipid protein displayed a selective down-regulation in subacute CDV leukoencephalitis, suggestive of an oligodendrocyte dystrophy. In contrast, a marked up-regulation of multiple immunoglobulin-like expressed sequence tags and the delta polypeptide of the CD3 antigen was observed in chronic CDV leukoencephalitis, in agreement with the hypothesis of an immune-mediated demyelination in the late inflammatory phase of the disease. Analysis of pathways intimately linked to demyelination as determined by morphometry employing correlation-based Gene Set Enrichment Analysis highlighted the pathomechanistic importance of up-regulated genes comprised by the gene ontology terms “viral replication” and “humoral immune response” as well as down-regulated genes functionally related to “metabolite and energy generation”.

Involvement of morbilliviruses in the pathogenesis of demyelinating disease

Two members of the morbillivirus genus of the family Paramyxoviridae, canine distemper virus (CDV) and measles virus (MV), are well-known for their ability to cause a chronic demyelinating disease of the CNS in their natural hosts, dogs and humans, respectively. Both viruses have been studied for their potential involvement in the neuropathogenesis of the human demyelinating disease multiple sclerosis (MS). Recently, three new members of the morbillivirus genus, phocine distemper virus (PDV), porpoise morbillivirus (PMV) and dolphin morbillivirus (DMV), have been discovered. These viruses have also been shown to induce multifocal demyelinating disease in infected animals. This review focuses on morbillivirus-induced neuropathologies with emphasis on aetiopathogenesis of CNS demyelination. The possible involvement of a morbillivirus in the pathogenesis of multiple sclerosis is discussed.

Canine distemper virus associated proliferation of canine footpad keratinocytes in vitro

Infection of canine footpads with canine distemper virus (CDV) can result in so-called hard pad disease characterized by footpad epidermal proliferation and hyperkeratosis. Cultured canine footpad keratinocytes (CFK) were inoculated with a virulent canine distemper virus strain (A75/17-CDV) to study the effects of CDV-infection on keratinocyte proliferation. Infection was analyzed by immunohistochemistry and in situ hybridization for CDV nucleoprotein (N-protein) antigen and mRNA. CDV caused a persistent, non-cytocidal infection with spread from single cells to infection of the confluent cell layer 7 days post infection (p.i.). Absolute cell numbers were significantly higher in infected cultures compared to control cultures from day 4 until day 6 p.i. Infected cultures contained significantly more total DNA on day 5 p.i. compared to controls. Immunohistochemical investigation of proliferation markers Ki67 and BrdU demonstrated a nearly two-fold increase in numbers of positive cells on day 5 p.i. compared to controls. These findings demonstrate that canine distemper virus infection of canine footpad keratinocytes in vitro was associated with proliferation.

Canine distemper virus-induced depletion of uninfected lymphocytes is associated with apoptosis

Canine distemper virus (CDV), a negative stranded RNA morbillivirus, causes a multisystemic disease in dogs, which is associated with a severe immune suppression. The aim of the study was to examine the influence of early CDV infection on leukocyte depletion, lymphopenia and virus-induced cell death in dogs infected with a virulent CDV strain. From 10 infected dogs, peripheral blood leukocytes were harvested periodically, phenotyped and analyzed for CDV antigen content and apoptosis using Annexin V-FITC and propidium iodide labeling. CDV infection induced a severe CD3⁺ T cell and CD21⁺ B cell depletion in all animals at 3 days post-infection (d.p.i.). For dogs with severe distemper, developing virus persistence in the lymphoid tissue and central nervous system, this lymphopenia lasted until the end of the experiment. Increased levels of lymphocyte apoptosis were found at 3 d.p.i., and monocyte apoptosis at 6 d.p.i. This was more prominent in the group of animals with severe distemper. At 3 d.p.i. no leukocyte infection was detectable indicating that the early lymphocyte depletion and apoptosis was not a direct consequence of virus infection. Taken together, our results demonstrate that CDV-induced lymphopenia is an early event and that the degree of lymphocyte depletion correlates with the severity of disease and virus persistence in the lymphoid tissue and central nervous system.

Demyelination in canine distemper virus infection: a review

Canine distemper virus (CDV) causes severe immunosuppression and neurological disease in dogs, associated with demyelination, and is a model for multiple sclerosis in man. In the early stage of the infection, demyelination is associated with viral replication in the white matter. In acute demyelinating lesions there is massive down-regulation of myelin transcription and metabolic impairment of the myelin-producing cells, but there is no evidence that these cells are undergoing apoptosis or necrosis. Oligodendroglial change is related to restricted infection of these cells (transcription but no translation) and marked activation of microglial cells in acute lesions. Concomitant with immunological recovery during the further course of the disease, inflammation occurs in the demyelinating plaques with progression of the lesions in some animals. A series of experiments in vitro suggests that chronic inflammatory demyelination is due to a bystander mechanism resulting from interactions between macrophages and antiviral antibodies. Autoimmune reactions are also observed, but do not correlate with the course of the disease. The progressive or relapsing course of the disease is associated with viral persistence in the nervous system. Persistence of CDV in the brain appears to be favored by non-cytolytic selective spread of the virus and restricted infection, in this way escaping immune surveillance in the CNS. The CDV Fusion protein appears to play an important role in CDV persistence. Similarities between canine distemper and rodent models of virus-induced demyelination are discussed.

Experimental Usutu virus infection of suckling mice causes neuronal and glial cell apoptosis and demyelination

Usutu virus (USUV), a mosquito-borne flavivirus of the Japanese encephalitis virus group has been responsible for avian mortality in Austria since 2001. In the present study, the neuropathogenicity and neuroinvasiveness of USUV for 1-week-old suckling mice was investigated. After intraperitoneal inoculation, clinical signs like depression, disorientation, paraplegia, paralysis and coma were observed between 6 and 11 days post infection. Histologically, there was widespread neuronal apoptosis especially in the brain stem. Inflammatory infiltrates were scarce. Apoptosis was also present in white matter of cerebellum, medulla and spinal cord, and was frequently accompanied by primary demyelination. While apoptosis of neurons was clearly associated with presence of viral signals, the cause of apoptosis of white matter cells was more ambiguous. However, focal immunostaining was found in the white matter, especially in the spinal cord. As with all flaviviruses, USUV proved to be neuropathogenic for mice. In contrast to other flaviviruses, neuroinvasion occurred only in animals that were not older than 1 week at the time of inoculation. While neuronal apoptosis is a general aspect of flavivirus pathogenicity, demyelination seems to be a unique feature of USUV infection.

Microglial cell activation in demyelinating canine distemper lesions

Microglia cells are the principal immune effector elements of the brain responding to any pathological event. To elucidate the possible role of microglia in initial non-inflammatory demyelination in canine distemper virus (CDV) infection, microglia from experimentally CDV infected dogs were isolated ex vivo by density gradient centrifugation and characterized immunophenotypically and functionally using flow cytometry. Results from dogs with demyelinating lesions were compared to results from recovered dogs and two healthy controls. CDV antigen could be detected in microglia of dogs with histopathologically confirmed demyelination. Microglia of these dogs showed marked upregulation of the surface molecules CD18, CD11b, CD11c, CD1c, MHC class I and MHC class II and a tendency for increased expression intensity of ICAM-1 (CD54), B7-1 (CD80), B7-2 (CD86), whereas no increased expression was found for CD44 and CD45. Functionally, microglia exhibited distinctly enhanced phagocytosis and generation of reactive oxygen species (ROS). It was concluded that in CDV infection, there is a clear association between microglial activation and demyelination. This strongly suggests that microglia contribute to acute myelin destruction in distemper.

Canine distemper, a re-emerging morbillivirus with complex neuropathogenic mechanisms

Paramyxoviruses are responsible for a wide variety of diseases both in humans and in animals. Common to many paramyxoviruses is the fact that they can cause neurological symptoms in their final host. Newly discovered paramyxoviruses, such as the Hendra and Nipah viruses, show the same pattern of pathogenesis as that of the paramyxoviruses already known. Canine distemper virus (CDV) is a well-studied member of the genus Morbillivirus. Study of the neuropathogenesis of CDV might give insight into disease mechanisms and suggest approaches for the prevention of other recently discovered paramyxovirus infections.

Emergence of Usutu virus, an African mosquito-borne flavivirus of the Japanese encephalitis virus group, central Europe

During late summer 2001 in Austria, a series of deaths in several species of birds occurred, similar to the beginning of the West Nile virus (WNV) epidemic in the United States. We necropsied the dead birds and examined them by various methods; pathologic and immunohistologic investigations suggested a WNV infection. Subsequently, the virus was isolated, identified, partially sequenced, and subjected to phylogenetic analysis. The isolates exhibited 97% identity to Usutu virus (USUV), a mosquito-borne Flavivirus of the Japanese encephalitis virus group; USUV has never previously been observed outside Africa nor associated with fatal disease in animals or humans. If established in central Europe, this virus may have considerable effects on avian populations; whether USUV has the potential to cause severe human disease is unknown.

GM1-gangliosidosis in Alaskan huskies: clinical and pathologic findings

Three Alaskan Huskies, two females and one male, were diagnosed with GM1-gangliosidosis. Clinically, diseased animals exhibited proportional dwarfism and developed progressive neurologic impairment with signs of cerebellar dysfunction at the age of 5-7 months. Skeletal lesions characterized by retarded enchondral ossification of vertebral epiphyses were revealed by radiographs of the male dog at 5.5 months of age. Histologic examination of the central nervous system (CNS) revealed that most neurons were enlarged with a foamy to granular cytoplasm due to tightly packed vacuoles that displaced the Nissl substance. Vacuoles in paraffin-embedded sections stained positively with Luxol fast blue and Grocott's method, and in frozen sections vacuoles were periodic acid-Schiff positive. Foamy vacuolation also occurred within neurons of the autonomic ganglia. Extracerebral cells such as macrophages and peripheral lymphocytes also displayed foamy cytoplasm and vacuolation. In the CNS of diseased animals, a mild demyelination and axonal degeneration was accompanied by a significant astrogliosis (P < 0.05) in the gray matter as compared with age- and sex-matched control dogs. There was also a significant loss (P < 0.05) of oligodendrocytes in the gray and white matter of affected animals as compared with controls. Ultrastructurally, the neuronal storage material consisted of numerous circular to concentric whorls of lamellated membranes or stacks of membranes in parallel arrays. GM1-gangliosidosis in Alaskan Huskies resembles beta-galactosidase deficiency in other canine breeds, and these CNS disorders may be a consequence of neuronal storage and disturbed myelin processing.

Doc-2/hDab2 expression is up-regulated in primary pancreatic cancer but reduced in metastasis

SUMMARY

DOC-2/hDab2 (DOC-2) has tumor suppressive functions in ovarian cancer and choriocarcinoma. In these tumors, it negatively influences mitogenic signal transduction of growth factors and blocks ras activity. Pancreatic cancer exhibits a high frequency of K-ras gene mutations; however, it is not known whether DOC-2 expression is altered in these tumors. Therefore, we investigated DOC-2 expression in 22 pancreatic adenocarcinomas and in 6 pancreatic cancer cell lines. Findings in human tumors were compared with normal controls and correlated with clinicopathological data. Additionally, the influence of K-ras on DOC-2 transcription was investigated. Northern blot and Western blot analyses both demonstrated an increase of DOC-2 mRNA and protein levels in primary pancreatic cancers in comparison with normal controls. In situ hybridization showed DOC-2 mRNA expression in the majority of cancer cells of primary tumors, as well as in chronic pancreatitis-like lesions surrounding the cancer mass. Immunohistochemistry mirrored the in situ hybridization findings. In contrast, levels of expression of DOC-2 in lymph node metastases were markedly decreased in comparison with levels in primary tumors. In addition, in 5 metastatic pancreatic cancer cell lines, DOC-2 mRNA and protein levels were low, whereas quantitative RT-PCR demonstrated relatively higher levels in a nonmetastatic pancreatic cancer cell line. In conclusion, DOC-2 is overexpressed in primary pancreatic adenocarcinoma but down-regulated in metastatic disease, suggesting a tumor suppressor function of DOC-2 in the late steps of pancreatic carcinogenesis.

KAI1 gene is differently expressed in papillary and pancreatic cancer: influence on metastasis

AIM:To compare KAI1 in cancer of papilla of Vater and pancreas to evaluate whether there are differences in biologic behavior which might account for prognosis.METHODS:We compared the expression in 24 papillay and 29 pancreatic cancers using Northern blot analysis, immunochemical assay and in situ hybridization, and investigated whether early diagnosis or molecular differences predict the outcome in these tumor entities.RESULTS:By Northern blot analysis there is no statistical difference of KAI1 levels in normal and cancerous papilla. No association between KAI1 mRNA expression and tumor stage or tumor differentiation was found in the tumors. By immunohistochemical assay, KAI1 staining in cytoplasm of papillary cancer cells was similar to that of normal papillary cells. By in situ hybridization, the results of KAI1 mRNA expression in normal and cancerous papilla were similar to those with immunohistochemical assay. The normal and cancerous pancreas tissues were also analyzed by the methods used in papillary samples.CONCLUSION:Although the biologic roles of KAI1 have not been clarified, our results suggest that KAI1 may restrict the progression of malignant papillary cancer, but its expression might not have any effect on the characteristics of papillary tumor, whereas by the analysis of KAI1 gene, its reduced expression is closely related to the progression and metastases of pancreatic cancer.

Matrix metalloproteinase 9 and vascular endothelial growth factor are essential for osteoclast recruitment into developing long bones

Bone development requires the recruitment of osteoclast precursors from surrounding mesenchyme, thereby allowing the key events of bone growth such as marrow cavity formation, capillary invasion, and matrix remodeling. We demonstrate that mice deficient in gelatinase B/matrix metalloproteinase (MMP)-9 exhibit a delay in osteoclast recruitment. Histological analysis and specialized invasion and bone resorption models show that MMP-9 is specifically required for the invasion of osteoclasts and endothelial cells into the discontinuously mineralized hypertrophic cartilage that fills the core of the diaphysis. However, MMPs other than MMP-9 are required for the passage of the cells through unmineralized type I collagen of the nascent bone collar, and play a role in resorption of mineralized matrix. MMP-9 stimulates the solubilization of unmineralized cartilage by MMP-13, a collagenase highly expressed in hypertrophic cartilage before osteoclast invasion. Hypertrophic cartilage also expresses vascular endothelial growth factor (VEGF), which binds to extracellular matrix and is made bioavailable by MMP-9 (Bergers, G., R. Brekken, G. McMahon, T.H. Vu, T. Itoh, K. Tamaki, K. Tanzawa, P. Thorpe, S. Itohara, Z. Werb, and D. Hanahan. 2000. Nat. Cell Biol. 2:737-744). We show that VEGF is a chemoattractant for osteoclasts. Moreover, invasion of osteoclasts into the hypertrophic cartilage requires VEGF because it is inhibited by blocking VEGF function. These observations identify specific actions of MMP-9 and VEGF that are critical for early bone development.

Expression of the multidrug-resistance 1 (MDR1) gene and prognosis in human pancreatic cancer

Multidrug-resistance 1 (MDR1) encodes a 170 kDa transmembrane glycoprotein (P-glycoprotein), which acts as a drug-efflux pump. In the present study, we analyzed the expression of MDR1/P-glycoprotein in human pancreatic cancer and correlated the results with clinical parameters. Pancreatic cancer tissue samples were obtained from 67 patients (30 female, 37 male) who underwent surgery. Normal pancreatic tissues obtained from 15 previously healthy organ donors (4 female, 11 male) served as controls. MDR1 mRNA levels were analyzed by Northern blotting, and the exact site of MDR1 mRNA expression was determined by in situ hybridization and immunohistochemistry. Northern blot analysis indicated that in comparison with the normal pancreas, MDR1 mRNA levels were only increased 1.4-fold (p = 0.03) in the pancreatic cancer samples. However, there was a 2.9-fold (p < 0.01) increase in MDR1 mRNA levels when only the samples that exhibited increased expression (38%) were analyzed. In situ hybridization and immunohistochemical analysis showed that MDR1 was highly expressed in the cancer cells of these samples. Statistical analysis revealed that patients with high MDR1/P-glycoprotein expression had a shorter postoperative survival time compared with patients with weak to moderate expression of MDR1. On the basis of in situ hybridization, survival in the intense group was 11.6 (n = 12) versus 14.2 months (n = 42) in the mild to moderate group. On the basis of immunohistochemistry, survival in the intense group was 7.5 months (n = 10) versus 14.1 months (n = 40) in the mild to moderate group. Surprisingly, survival of patients with high expression of MDR1/P-glycoprotein was not significantly different from that of patients without detectable MDR1/P-glycoprotein expression. These findings suggest that both strong expression of MDR1/P-glycoprotein and lack of expression seem to influence tumor growth via known and yet unknown mechanisms.

Reduced expression of the metastasis suppressor gene KAI1 in advanced colon cancer and its metastases

BACKGROUND

The expression of the KAI1 gene and its gene product were studied in metastatic and non-metastatic human colorectal cancer to evaluate its role in the metastatic process.

METHODS

KAI1 mRNA and protein expression was examined in 36 primary colorectal carcinomas and 6 liver metastasis using Northern blot and Western blot analyses. Forty-six normal colonic tissue samples served as controls. The exact site of KAI1 expression was analyzed by in situ hybridization and by immunohistochemistry in primary tumors, in the corresponding normal tissues, in lymph node metastases and liver metastases.

RESULTS

Densitometric analysis of Northern blots revealed overexpression of KAI1 mRNA in 87% of colonic cancer tissues in comparison with the corresponding normal colonic tissues. This increase was 9.1-fold in median (P < .001). KAI1 mRNA expression was strongly dependent on tumor stage. Colorectal cancer at stages II and III revealed significantly higher KAI1 mRNA levels than stage IV tumors (P < .03 and P < .015, respectively) or normal controls. In addition, liver metastases showed reduced KAI1 mRNA expression when compared with their corresponding primary tumor. In situ hybridization confirmed the stage-dependent expression results obtained by Northern blots, in which the KAI1 mRNA signal was exhibited almost exclusively in the epithelial cells. Lymph node and liver metastases were largely devoid of KAI1 mRNA. Western blot analysis showed a highly significant increase of KAI1 protein level in stage II cancers in comparison with the normal colon (P < .001) but also in comparison with the more advanced tumor stages III and IV (P < .03) and P < .02, respectively), when metastases were already present. In accordance, KAI1 immunostaining decreased successively with the advance of the tumor stage and was absent in lymph node and liver metastases.

CONCLUSIONS

These data demonstrate that the KAI1 mRNA expression and the KAI1 protein level increase in an earlier tumor stage of colorectal cancer, decrease in advanced stages, and are lost in metastases. The loss of KAI1 might favor the ability of colorectal cancer cells to metastasize.

Connective tissue growth factor is a regulator for fibrosis in human chronic pancreatitis

OBJECTIVE

To evaluate the parameters that mediate fibrogenesis in chronic pancreatitis (CP).

BACKGROUND

Connective tissue growth factor (CTGF), which is regulated by transforming growth factor beta (TGF-beta), has recently been implicated in skin fibrosis and atherosclerosis. In the present study, the authors analyzed the concomitant presence of TGF-beta1 and its signaling receptors-TGF-beta receptor I, subtype ALK5 (TbetaR-I(ALK5)), and TGF-beta receptor II (TbetaR-II)-as well as CTGF and collagen type I in the pancreatic tissue of patients undergoing surgery for chronic pancreatitis.

PATIENTS AND METHODS

CP tissue samples were obtained from 40 patients (8 women, 32 men) undergoing pancreatic resection. Tissue samples of 25 previously healthy organ donors (12 women, 13 men) served as controls. The expression of TGF-beta1, TbetaR-I(ALK5), TbetaR-II, CTGF, and collagen type I was studied by Northern blot analysis. By in situ hybridization and immunohistochemistry, the respective mRNA moieties and proteins were localized in the tissue samples.

RESULTS

Northern blot analysis showed that CP tissue samples exhibited concomitant enhanced mRNA expression of TGF-beta1 (38-fold), TbetaR-II (5-fold), CTGF (25-fold), and collagen type I (24-fold) compared with normal controls. In addition, TbetaR-I(ALK5) mRNA was increased in 50% of CP tissue samples (1.8-fold). By in situ hybridization, TGF-beta1, TbetaR-I(ALK5), and TbetaR-II mRNA were often seen to be colocalized, especially in the ductal cells and in metaplastic areas where atrophic acinar cells appeared to dedifferentiate into ductal structures. In contrast, CTGF was located in degenerating acinar cells and principally in fibroblasts surrounding these areas. Moreover, CTGF mRNA expression levels correlated positively with the degree of fibrosis in CP tissues.

CONCLUSION

The concomitant overexpression of CTGF, collagen type I, TGF-beta1, and its signaling receptors in CP suggests that these proteins contribute to enhanced extracellular matrix synthesis and accumulation, resulting finally in the fibrogenesis observed in CP.

In vivo expression of transcripts encoding the Glvr-1 phosphate transporter/retrovirus receptor during bone development

In vitro observations suggest that inorganic phosphate (Pi) transport plays an important functional role in osteogenic cells and in their matrix vesicles for the initiation of matrix calcification. Recent studies have shown that the type III sodium-dependent Pi transporters, Glvr-1 and Glvr-2, are expressed in human osteoblast-like cells and have suggested a potential role for type III transporters in regulated Pi handling in osteogenic cells. To address the relevance of these findings in the context of bone formation in vivo and, in particular, in relation to matrix calcification, we investigated expression of the Glvr-1 transporter by in situ hybridization in developing embryonic murine metatarsals, using human Glvr-1 cDNA as a probe. In this model of endochondral ossification, expression of transcripts encoding Glvr-1 could be detected from day 17 of embryonic development. A hybridization signal for Glvr-1 was specifically observed in a subset of hypertrophic chondrocytes and could not be detected in osteoblasts. The expression of Glvr-1 mRNA was compared with that of transcripts encoding extracellular matrix proteins. Glvr-1 mRNA expression was confined to a population of early hypertrophic chondrocytes expressing type X collagen and to slightly more mature cells that express transcripts encoding osteopontin but lack type X collagen mRNA. No Glvr-1 transcripts were detected in fully differentiated hypertrophic chondrocytes. This pattern of Glvr-1 mRNA expression was maintained throughout embryonic development until after birth. In conclusion, the Glvr-1 phosphate transporter is selectively expressed in a subset of hypertrophic chondrocytes during endochondral bone formation, in a region where matrix mineralization proceeds. This observation represents the first in vivo evidence consistent with a potential role for this phosphate transporter in matrix calcification.

KAI1, a new metastasis suppressor gene, is reduced in metastatic hepatocellular carcinoma

Down-regulation of KAI1 expression has been shown to be associated with formation of metastases or disease progression in prostate and pancreatic cancer. In the present study we analyzed the expression pattern of KAI1 in metastatic and nonmetastatic hepatocellular carcinomas (HCCs) in comparison with normal livers to evaluate whether alteration of KAI1 also facilitates the metastatic ability in this malignancy. Thirty-nine primary HCCs and 10 normal liver tissue samples were studied for KAI1 messenger RNA (mRNA) expression with use of Northern blot analysis and in situ hybridization. By Northern blot analysis, moderate to strong KAI1 mRNA expression was present in normal liver samples. In contrast, KAI1 mRNA expression in tissue samples of primary HCCs was markedly decreased compared with normal controls. The normal/tumor ratio of KAI1 mRNA expression was 2.6:1 (P <.01). Primary HCCs that gave rise to metastasis showed significantly lower KAI1 mRNA levels than nonmetastasized HCCs (P <. 05). As seen by in situ hybridization, moderate to strong cytoplasmic KAI1 mRNA staining was present in almost all normal hepatocytes. Bile ducts, blood vessels, and connective tissue showed no or only faint KAI1 mRNA expression in the normal liver samples. In nonmetastatic HCCs, the cancer cells exhibited in situ hybridization signals that were similar to the normal controls. In contrast, most of the primary HCC cells in samples with metastases showed only faint or moderate KAI1 mRNA expression predominantly in the perinuclear regions. When KAI1 mRNA expression of primary hepatocellular cancer cells was compared with metastasized cancer cells in lymph nodes, with intrahepatic satellite metastasis, or with peritoneal metastasis in the same patients, significantly lower (P <.01) KAI1 mRNA levels were present in the metastasized HCC cells. Reduced KAI1 mRNA in HCC cells seems to influence their metastatic ability and thereby enhances the malignant potential of HCC.

Cytokine mRNA expression in whole blood samples from dogs with natural canine distemper virus infection

Cytokines are soluble polypeptides with many physiological functions and a special role during infection and inflammation. Little is known about cytokine regulation in naturally occurring viral diseases of animals. Especially the role of cytokines in the development and progression of lesions in canine distemper virus (CDV) infection in dogs is largely unknown. Whole blood samples from 14 dogs with CDV infection and three dogs suffering from non-distemper diseases were examined for mRNA of pro-inflammatory cytokines such as interleukin-1beta (IL-1), interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-12 (IL-12), tumor necrosis factor-alpha (TNF), interferon-gamma (IFN), and the anti-inflammatory transforming growth factor-beta1 (TGF) using reverse transcription polymerase chain reaction (RT-PCR). Blood samples from the three dogs that showed no clinical abnormalities during a pre-vaccination physical examination served as control. CDV infection was confirmed by post-mortem immunohistochemistry for CDV nucleoprotein. The degree of immunoreactivity and the number of virus antigen positive organs were expressed as antigen index. IFN transcripts were not identified in any dog and IL-8 transcripts were present in RNA isolates from all 20 dogs. None of the other cytokines was detected in control animals. IL-1 and IL-6 were each found in one non-distemper dog and TGF transcripts were amplified in two dogs with non-distemper disease. The following transcripts were found in variable numbers in distemper dogs: IL-1 (7/14 dogs), IL-6 (3/14 dogs), IL-12 (3/14 dogs), TNF (8/14 dogs), and TGF (10/14 dogs) with multiple cytokines in ten dogs. No cytokine transcripts were detected in three distemper dogs. There was no obvious correlation between cytokine mRNA expression and respiratory and gastrointestinal tract diseases. In the CNS, demyelination was frequently associated with IL-1, IL-12, TNF and TGF mRNA expression in the blood. IL-6 transcripts were found only in animals with early CNS lesions and TGF was the only detectable cytokine in an animal with chronic demyelination. Lack of detectable cytokine transcripts in whole blood samples was associated with a high antigen index and viremia, indicating that an overwhelming virus infection may suppress cytokine production, possibly due to paralysis of the immune system. Simultaneous occurrence of pro- and anti-inflammatory cytokines in whole blood preparation from most of the dogs with distemper, indicated a complex most likely disease stage dependent orchestrated cytokine expression.

In situ hybridization and immunohistochemistry for prion protein (PrP) in bovine spongiform encephalopathy (BSE)

In about 5% of the cows showing clinical signs of bovine spongiform encephalopathy (BSE) the histopathological examination is not conclusive. In order to rule out BSE in these cases, additional methods are necessary. For that reason, non-radioactive in situ hybridization (ISH) was performed using a riboprobe against the messenger RNA coding for the prion protein (PrP). In addition, a polyclonal antibody for immunohistochemistry (IHC) was generated against a synthetic peptide derived from bovine PrP. ISH and IHC were used to analyse brain sections of cattle suffering from BSE and various neurological diseases including four cows with clinically suspect but histologically unconfirmed BSE. ISH revealed no differences in localization, distribution and neuronal levels of PrP mRNA between BSE positive and negative cattle. However, there was a BSE-specific staining pattern in IHC allowing to exclude BSE the four suspected cases. Additionally, IHC for PrP is an elegant alternative to search for scrapie associated fibrils by electron microscopy.