Laura Nordio

Widespread extrahepatic expression of acute-phase proteins in healthy chicken (Gallus gallus) tissues

Acute phase proteins (APP) are plasma proteins that can modify their expression in response to inflammation caused by tissue injury, infections, immunological disorders or stress. Although APP are produced mainly in liver, extrahepatic production has also been described. As a prerequisite to get insight the expression of APP in chicken during diseases, this study investigated the presence of five APP, including alpha1-acid glycoprotein (AGP), Serum Amyloid A (SAA), PIT54, C-Reactive protein (CRP) and Ovotransferrin (OVT) in twenty tissues collected from healthy chicken (Gallus gallus) by quantitative Real Time PCR and immunohistochemistry. As expected, APP gene abundance was higher in liver compared with other tissues. The mRNA coding for CRP, OVT and SAA was detected in all analyzed tissues with a higher expression in gastrointestinal tract, respiratory and lymphatic samples. SAA expression was particularly high in cecal tonsil, lung, spleen and Meckels diverticulum, whereas OVT in lung, bursa of Fabricius and pancreas. AGP and PIT54 mRNA expression were detected in all tissues but at negligible levels. Immunohistochemical expression of AGP and OVT was variably detected in different organs, being identified in endothelium of every tissue. Positive cells were present in the epithelium of the mucosal layer of gastrointestinal tract and kidney. Lung and central nervous system stained for both proteins. No positive staining was detected in lymphoid tissues and muscle. These results suggest that most tissues can express different amount of APP even in healthy conditions and are therefore capable to mount a local acute phase reaction.

Generation of a new mouse model of glaucoma characterized by reduced expression of the AP-2β and AP-2δ proteins

We generated 6 transgenic lines with insertion of an expression plasmid for the R883/M xanthine dehydrogenase (XDH) mutant protein. Approximately 20% of the animals deriving from one of the transgenic lines show ocular abnormalities and an increase in intra-ocular pressure which are consistent with glaucoma. The observed pathologic phenotype is not due to expression of the transgene, but rather the consequence of the transgene insertion site, which has been defined by genome sequencing. The insertion site maps to chromosome 1qA3 in close proximity to the loci encoding AP-2β and AP-2δ, two proteins expressed in the eye. The insertion leads to a reduction in AP-2β and AP-2δ levels. Down-regulation of AP-2β expression is likely to be responsible for the pathologic phenotype, as conditional deletion of the Tfap2b gene in the neural crest has recently been shown to cause defective development of the eye anterior segment and early-onset glaucoma. In these conditional knock-out and our transgenic mice, the morphological/histological features of the glaucomatous pathology are surprisingly similar. Our transgenic mouse represents a model of angle-closure glaucoma and a useful tool for the study of the pathogenesis and the development of innovative therapeutic strategies.

Fibrosarcoma of the eyelid in two sibling Czech wolfdogs

Most canine tumors of the eyelid are tumors generally encountered in the skin. They are most commonly of epithelial origin and benign. In this report, we describe the cases of two sibling Czech wolfdogs presented, one year apart, with a subcutaneous mass involving the left eyelid. Both lesions were histologically consistent with a diagnosis of subcutaneous fibrosarcoma. Immunohistochemical analyses of the tumors revealed a mild positivity for vimentin and negativity for GFAP, desmin, αSMA, myoglobin, S100, PNL2 and calponin, excluding all differential diagnosis (i.e. peripheral nerve sheath tumor, melanoma, perivascular sarcoma, myofibroblastic sarcoma, rhabdomyosarcoma). To the best of authors’ knowledge, this is the first report of canine eyelid fibrosarcoma. Since this rare tumor has been observed in two full siblings, we could speculate the existence of some genetic predisposition to sarcoma, however the present data did not allow any definite conclusion on the etiopathogenesis or genetic basis of these tumors.

Immunohistochemical Expression of FXR1 in Canine Normal Tissues and Melanomas

Fragile X mental retardation-related protein 1 (FXR1) is a cytoplasmic RNA-binding protein highly conserved among vertebrates. It has been studied for its role in muscle development, inflammation, and tumorigenesis, being related, for example, to metastasizing behavior in human and canine uveal melanoma. Anti-FXR1 antibodies have never been validated in the canine species. To investigate FXR1 expression in canine melanocytic tumors, the present study tested two commercially available polyclonal anti-human FXR1 antibodies, raised in goat and rabbit, respectively. The cross-reactivity of the anti-FXR1 antibodies was assessed by Western blot analysis, and the protein was localized by IHC in a set of normal canine tissues and in canine melanocytic tumors (10 uveal and 10 oral). Western blot results demonstrated that the antibody raised in rabbit specifically recognized the canine FXR1, while the antibody raised in goat did not cross-react with this canine protein. FXR1 protein was immunodetected using rabbit anti-FXR1 antibody, in canine normal tissues with different levels of intensity and distribution. It was also detected in 10/10 uveal and 9/10 oral melanocytic tumors. The present study validated for the first time the use of anti-FXR1 antibody in dogs and highlighted different FXR1 protein expression in canine melanocytic tumors, the significance of which is undergoing further investigations.

Validation of anti-FXR1 antibodies in the canine species and application to an immunohistochemical study of canine oral melanomas

FXR1 (Fragile X mental retardation-related protein 1) is a cytoplasmic RNA binding protein, which genetic expression has been related to metastatic potential in human melanoma. The aims of the present study were: the validation of two commercially available clones of polyclonal anti-human FXR1 antibody in dogs; their application to investigate FXR1 expression in a group of canine oral melanomas. Anti-FXR1 antibody was not previously validated in the canine species. Two different commercially available polyclonal anti-FXR1 antibodies (respectively made in goat and in rabbit) were used. FXR1 protein in canine serum was identified by western blot after SDS-PAGE, using human serum as control. FXR1 immunohistochemical expression was tested in a series of normal tissues, that are expected to express FXR1, and in 31 cases of oral melanomas. The final immunohistochemical protocol used heat-induced unmasking and overnight incubation. FXR1 protein bands in canine serum were detected by tested antibodies, in a more specific way by the rabbit antibody. FXR1 immunohistochemical staining was positive in all tested organs, with different levels of expression. FXR1 was also expressed in 31/31 tested melanomas, with variable intensity and percentage of positive cells (Figure 1). Equal results were achieved with the two antibodies in 8 cases of melanoma, whereas there were variable differences in 22, and one case stained only with goat antibody. The rabbit antibody gave less background staining. This study validated anti-FXR1 antibodies for use in the canine species. This protein was expressed in various normal tissues, as well as in the tested neoplasms. Significance of different level of expression is undergoing evaluation with further studies.

LTA4H expression in canine oral melanomas: methodological set up and preliminary results

Leukotriene A4 hydrolase (LTA4H) is a hydrolytic enzyme which converts leukotriene A4 into leukotriene B4 inside the arachidonic acid cascade. Besides playing a well-known role in inflammation, it has also been investigated for possible implications in different types of tumors, including canine uveal melanoma (Chen et al., 2004; Malho et al., 2013). In the present study, we set up RT-PCR and immunohistochemical protocols to investigate the expression of LTA4H gene and protein, respectively, in formalin fixed paraffin embedded (FFPE) specimens of canine melanomas. 16 samples of canine oral melanomas were histopathologically evaluated and divided in two subgroups based on morphological criteria of malignancy. RT-PCR protocols for the target gene LTA4H were set up on frozen and FFPE samples of the same tumor. Immunohistochemical investigation of LTA4H protein was performed with a mouse monoclonal antibody anti-LTA4H (clone 1E9). Preliminary tests were carried out to define the protocol: with and without bleaching, with different unmaskings, with different serial dilutions of the primary antibody. RT-PCR set up resulted in comparable good efficiency on both frozen and FFPE samples. Final immunohistochemical protocol included: hydrogen peroxide bleaching, water bath unmasking and 1:100 dilution of the primary antibody. Positive immunostaining for LTA4H was present in neoplastic cells of all melanoma samples, with variable localization and intensity. These preliminary results encourage future applications of the studied techniques to quantify differential expression of LTA4H in canine melanomas both at molecular and histological level. Laboratory results will be compared with follow up data, in order to verify if LTA4H can be proposed as a valuable prognostic marker.