Central nervous system mycobacteriosis caused by Mycobacterium genavense in degus (Octodon degus).

Degus (Octodon degus) that were kept at a breeding facility presented with neurological or respiratory symptoms and died. Necropsies were performed on 9 individuals, and no significant gross lesions were found. Histologically, spinal cord necrosis was observed in all 9 cases and granulomatous myelitis in 5 of the 9 cases. Locally extensive necrosis of the brain and encephalitis were observed in 7 of the 9 cases. Acid-fast bacteria were found in the spinal cords, brains, and lungs from all 9 cases. Immunohistochemically, Mycobacterium tuberculosis antigen was observed in the spinal cords, brains, and lungs from all 9 cases. Double-labeling immunofluorescence revealed M. tuberculosis antigen in IBA1- and myeloperoxidase-immunopositive cells. Extracted genomic DNA from 8 of the 9 cases was successfully amplified with the primers for Mycobacterium genavense ITS1 and hypothetical 21 kDa protein genes, and the polymerase chain reaction products were identified as M. genavense by DNA sequencing. This report highlights the susceptibility of degus to M. genavense infection in the central nervous system.

Histopathological features and immunophenotyping of canine transmural gastrointestinal lymphoma using full-thickness biopsy samples.

To elucidate the histopathological characteristics and immunophenotypes of canine transmural "mass-forming" gastrointestinal lymphomas and plasmacytomas, 83 surgically resected biopsy samples were examined. All lymphomas and plasmacytomas were located in the small or large intestine except for 1 plasmacytoma which was in the stomach. According to the World Health Organization (WHO) classification, B-cell neoplasms (17 cases) included lymphoplasmacytic lymphoma (6/17), plasmacytoma (5/17), follicular lymphoma (3/17), and diffuse large B-cell lymphoma (3/17). Based on nuclear sizes, T-cell neoplasms (66 cases) were broadly divided into large cell lymphoma (LCL; 48/66) and small cell lymphoma (SCL; 18/66). According to the WHO classification, T-cell neoplasms included anaplastic large T-cell lymphoma (ALCL; 10/66), angiotropic T-cell lymphoma (3/66), mixed inflammatory type peripheral T-cell lymphoma (mixed inflammatory type PTCL; 33/66), and PTCL-not otherwise specified (PTCL-NOS; 20/66). Mixed inflammatory type PTCLs were further divided into histiocyte- (27/33) and eosinophil- (6/33) dominant types. Immunohistochemically, lymphoplasmacytic lymphomas were positive for Pax5 (6/6) and IgM (5/6), while plasmacytomas were positive for IgG (5/6) and negative for Pax5. LCLs were immunopositive for granzyme B in 31/48 cases (65%) and CD8 in 9/48 cases (19%), while SCLs were immunopositive for granzyme B in 3/18 cases (17%) and CD8 in 3/18 cases (17%). Furthermore, 8/10 cases (80%) of ALCL and 19/27 cases (70%) of histiocyte-dominant PTCL were immunopositive for granzyme B, whereas 6/20 cases (30%) of PTCL-NOS, 1/6 cases (17%) of eosinophil-dominant PTCL, and no cases of angiotropic T-cell lymphomas were immunopositive for granzyme B. The present study describes the immunophenotypes in different histological types of transmural gastrointestinal lymphomas in the dog.

Intraepithelial lymphocytes are associated with epithelial injury in feline intestinal T-cell lymphoma.

Our previous study indicated that cytotoxicity of intraepithelial lymphocytes is a poor prognostic factor in feline intestinal T-cell lymphoma (FITL), but the effect of cytotoxic lymphocytes on mucosal epithelium is still unknown. Thus, we investigated the association between cytotoxic lymphocytes and mucosal epithelium in 71 cases of feline intestinal T-cell lymphoma (FITL): epithelial injury, basement membrane injury, cleaved-caspase-3 positivity of epithelial cells, and the number and Ki67 positivity of intraepithelial lymphocytes in granzyme B (GRB)+ and GRB- FITLs were evaluated. Epithelial injury score and the number of intraepithelial lymphocytes in granzyme B (GRB)+ FITL were significantly higher than those of GRB- FITL (P<0.05, P<0.05), but no significant differences were found in the basement membrane injury score, the percentage of cleaved-caspase-3+ epithelial cells, and the percentage of Ki67+ intraepithelial lymphocytes. There was a significant correlation between the epithelial injury score and the number of intraepithelial lymphocytes (P<0.05), but no significant correlation was observed between the epithelial injury score and Ki67+ percentage of intraepithelial lymphocytes. Because epithelial cell cleaved-caspase-3 positivity was observed in FITL, regardless of GRB expression in lymphocytes, GRB-mediated apoptosis may not contribute to epithelial injury in FITL. The association between increased number of intraepithelial lymphocytes and epithelial injury suggests that intraepithelial lymphocytes infiltration may contribute to epithelial injury in FITL.

Application of automated machine learning for histological evaluation of feline endoscopic samples.

Differentiating intestinal T-cell lymphoma from chronic enteropathy (CE) in endoscopic samples is often challenging. In the present study, automated machine learning systems were developed to distinguish between the two diseases, predict clonality, and detect prognostic factors of intestinal lymphoma in cats. Four models were created for four experimental conditions: experiment 1 to distinguish between intestinal T-cell lymphoma and CE; experiment 2 to distinguish large cell lymphoma, small cell lymphoma, and CE; experiment 3 to distinguish granzyme B+ lymphoma, granzyme B- lymphoma, and CE; and experiment 4 to distinguish between T-cell receptor (TCR) clonal population and TCR polyclonal population. After each experiment, a pathologist reviewed the test images and scored for lymphocytic infiltration, epitheliotropism, and epithelial injury. The models of experiments 1-4 achieved area under the receiver operating characteristic curve scores of 0.943 (precision, 87.59%; recall, 87.59%), 0.962 (precision, 86.30%; recall, 86.30%), 0.904 (precision, 82.86%; recall, 80%), and 0.904 (precision, 81.25%; recall, 81.25%), respectively. The images predicted as intestinal T-cell lymphoma showed significant infiltration of lymphocytes and epitheliotropism than CE. These models can provide evaluation tools to assist pathologists with differentiating between intestinal T-cell lymphoma and CE.

Hepatosplenic T-cell lymphoma with hepatocytotropism in a cat.

CASE SUMMARY: A 14-year 3-month-old spayed female mixed-breed cat presented with jaundice, anaemia and thrombocytopenia. Haemophagocytic syndrome associated with lymphoma was suspected after cytological examination of the spleen. Despite treatment with prednisolone, L-asparaginase and nimustine, the cat died 176 days after the initial presentation. Necropsy revealed splenomegaly and hepatomegaly, without lymphadenopathy. Histopathologically, neoplastic lymphoid cells infiltrated the hepatic sinusoid and splenic sinus. The neoplastic lymphoid cells showed marked hepatocytotropism and contained erythrocytes, which was also confirmed by electron microscopy. Immunohistochemically, neoplastic lymphoid cells were positive for CD3, TIA1 (GMP-17) and granzyme B, and negative for CD8, CD20, CD56, CD57, CD79a and Iba1. Based on these findings, the cat was diagnosed with hepatosplenic T-cell lymphoma (HS-TCL) with hepatocytotropism. RELEVANCE AND NOVEL INFORMATION: This case shows cytotoxic immunophenotype of HS-TCL in a cat, which has not been demonstrated before. Severe hepatocytotropism and haemophagocytosis of the neoplastic cells were likely to be associated with jaundice and anaemia, respectively, and the poor outcome of the present case.

Establishment and Characterization of Monoclonal Antibody Against Canine CD8 Alpha.

Understanding of the microenvironment of cancer plays a crucial role in cancer research. A tool is needed to evaluate the immune cells surrounding the cancer cells. This study establishes and evaluates a novel monoclonal antibody against canine CD8α (cCD8α). The antibody was produced by immunization of rats with cCD8α-expressing cells. After establishment and selection of hybridoma cells, the clone F3-B2 was established. The reactivity of F3-B2 was confirmed using cCD8α-overexpressing murine cells. Flow cytometric analysis also demonstrated that F3-B2 reacts with cCD8α naturally expressed in canine peripheral blood mononuclear cells and a canine T cell lymphoma cell line. The specimens of lymphoid tissue showed immunohistochemical staining for F3-B2. Moreover, we also found that F3-B2 exhibited reactivity against feline CD8. Thus, this antibody provides a good research tool to analyze CD8-positive cytotoxic lymphocytes in canine and feline tumors.

Membrane Dynamics Induced by a Phosphatidylinositol 3,4,5-Trisphosphate Optogenetic Tool.

Membrane dynamic structures such as filopodia, lamellipodia, and ruffles have important cellular functions in phagocytosis and cell motility, and in pathological states, such as cancer metastasis. Phosphatidylinositol 3,4,5-trisphosphate (PIP3) is a crucial lipid that regulates PIP3 dynamics. Investigations of how PIP3 is involved in these functions have mainly relied on pharmacological interventions, and therefore have not generated detailed spatiotemporal information concerning membrane dynamics upon PIP3 production. In the present study, we applied an optogenetic approach using the CRY2-CIBN system. Using this system, we revealed that local PIP3 generation induced directional cell motility and membrane ruffles in COS7 cells. Furthermore, combined with structured illumination microscopy (SIM), membrane dynamics were investigated with high spatial resolution. We observed PIP3-induced apical ruffles and unique actin fiber behavior in that a single actin fiber protruded from the plasma membrane was taken up into the plasma membrane without depolymerization. This system has the potential to investigate other high-level cell motility and dynamic behaviors, such as cancer cell invasion and wound healing with high spatiotemporal resolution, and could provide new insights of biological sciences for membrane dynamics.

Leydig cell tumor in an Amur tiger (Panthera tigris altaica).

A 14-year and 8-month-old intact male Amur tiger presented with an enlarged left testis, measuring 5.7 × 5.5 × 4.5 cm. The cut surface was mottled dark red to reddish brown in color. Microscopically, the enlarged left testis comprised round or polygonal neoplastic cells arranged in a diffuse sheet pattern. These neoplastic cells had a hyperchromatic nucleus and an abundant eosinophilic cytoplasm. Immunohistochemically, these neoplastic cells were positive for vimentin, chromogranin A, synaptophysin, melan-A, inhibin-α, and S100 and negative for desmin and WT-1. Based on these morphological and immunohistochemical findings, the tumor was diagnosed as a Leydig cell tumor.