Arginine is a disease modifier for polyQ disease models that stabilizes polyQ protein conformation.

The polyglutamine (polyQ) diseases are a group of inherited neurodegenerative diseases that include Huntington's disease, various spinocerebellar ataxias, spinal and bulbar muscular atrophy, and dentatorubral pallidoluysian atrophy. They are caused by the abnormal expansion of a CAG repeat coding for the polyQ stretch in the causative gene of each disease. The expanded polyQ stretches trigger abnormal ß-sheet conformational transition and oligomerization followed by aggregation of the polyQ proteins in the affected neurons, leading to neuronal toxicity and neurodegeneration. Disease-modifying therapies that attenuate both symptoms and molecular pathogenesis of polyQ diseases remain an unmet clinical need. Here we identified arginine, a chemical chaperone that facilitates proper protein folding, as a novel compound that targets the upstream processes of polyQ protein aggregation by stabilizing the polyQ protein conformation. We first screened representative chemical chaperones using an in vitro polyQ aggregation assay, and identified arginine as a potent polyQ aggregation inhibitor. Our in vitro and cellular assays revealed that arginine exerts its anti-aggregation property by inhibiting the toxic ß-sheet conformational transition and oligomerization of polyQ proteins before the formation of insoluble aggregates. Arginine exhibited therapeutic effects on neurological symptoms and protein aggregation pathology in Caenorhabditis elegans, Drosophila, and two different mouse models of polyQ diseases. Arginine was also effective in a polyQ mouse model when administered after symptom onset. As arginine has been safely used for urea cycle defects and for mitochondrial myopathy, encephalopathy, lactic acid and stroke syndrome patients, and efficiently crosses the blood-brain barrier, a drug-repositioning approach for arginine would enable prompt clinical application as a promising disease-modifier drug for the polyQ diseases.

Mutations in the fifth immunoglobulin-like domain of kit are common and potentially sensitive to imatinib mesylate in feline mast cell tumours.

The purpose of the current study was to investigate the mutation status of KIT in feline mast cell tumours (MCTs) and to examine the effects of tyrosine kinase inhibition on the phosphorylation of mutant kit in vitro and in clinical cases of cats. Sequence analysis of KIT identified mutations in 42/62 MCTs (67.7%). The vast majority of the mutations were distributed in exons 8 and 9, both of which encode the fifth immunoglobulin-like domain (IgD) of kit. All five types of kit with a mutation in the fifth IgD were then expressed in 293 cells and examined for phosphorylation status. The mutant kit proteins showed ligand-independent phosphorylation. The tyrosine kinase inhibitor imatinib mesylate suppressed the phosphorylation of these mutant kit proteins in transfectant cells. In a clinical study of 10 cats with MCTs, beneficial response to imatinib mesylate was observed in 7/8 cats that had a mutation in the fifth IgD of kit in tumour cells. Mutations in the fifth IgD of kit thus appear to be common and potentially sensitive to imatinib mesylate in feline MCTs. These data provide an in vivo model for paediatric mastocytosis where mutations in the fifth IgD of kit also occur.

Immunophenotyping and gene rearrangement analysis in dogs with lymphoproliferative disorders characterized by small-cell lymphocytosis.

Lymphocytosis caused by neoplastic proliferation of small lymphocytes is occasionally difficult to distinguish by morphological examination from nonneoplastic lymphocytosis. To examine the clinical utility of gene rearrangement analysis for demonstrating neoplastic proliferation of small lymphocytes, gene rearrangement analysis was performed in comparison with immunophenotyping using peripheral lymphocytes in dogs with small lymphocytosis. Thirty-one dogs with small-cell lymphocytosis (8,100-884,300/microl) were enrolled. By immunophenotyping, lymphocytosis of all dogs was suggested to be neoplastic in nature based on the detection of marked expansion of phenotypically homogeneous lymphocytes or the presence of an aberrant antigen-expressing population of lymphocytes. In contrast, gene rearrangement analysis represented clonality in 27 dogs (detection rate of 87%). From the present study, gene rearrangement analysis was considered to be worthwhile to strengthen the evidence of neoplastic proliferation of small lymphocytes when coupled with immunophenotyping and to be a suitable diagnostic substitute if immunophenotyping is not available in clinical practice.

Expression of canine Kdap in normal, hyperplastic and neoplastic epidermis.

Keratinocyte differentiation-associated protein, Kdap, is a recently identified small secretory protein that may act as a soluble regulator for the cornification and/or desquamation of keratinocytes. To clarify the role of Kdap in the terminal differentiation of keratinocytes, detailed in situ localisation of Kdap was studied using canine skin with normal, hyperplastic and neoplastic epidermis. In normal canine trunk skin, Kdap was expressed by granular keratinocytes, with polarity to the apical side of the cells, suggesting that canine Kdap is present in lamellar granules, as in humans. Expression of Kdap was widespread in the spinous layers in hyperplastic epidermis, but was undetectable in squamous cell carcinomas. These findings suggest that Kdap is closely related to the delay of terminal differentiation and/or release of cells in hyperplastic epidermis.

Induction of dendritic cell-mediated immune responses against canine malignant melanoma cells.

To establish the basis for the use of dendritic cells (DC) in the treatment of canine melanoma, dogs were vaccinated using autologous DC pulsed with canine melanoma CMM2 cell lysate in the presence of keyhole limpet haemocyanin (KLH) in vitro (CMM2-KLH-DC), and the induction of immune responses against CMM2 cells in vivo was examined using the delayed-type hypersensitivity (DTH) skin test. The DTH responses against CMM2 cells and KLH were observed in dogs vaccinated with CMM2-KLH-DC, while the responses against KLH but not CMM2 cells were detected with DC pulsed with KLH alone (KLH-DC). Recruitment of CD8 and CD4 T cells was detected in the positively responding sites, suggested that vaccination with CMM2-KLH-DC efficiently elicits T cell-mediated immunity against CMM-2 cells in vivo. These findings demonstrate the potential utility of DC-based tumour vaccination in the treatment of canine malignant melanoma.

Generation of monoclonal antibody against canine neural-cell adhesion molecule.

A monoclonal antibody, K9BYU, was generated using Escherichia coli recombinant extracellular domain of canine neural-cell adhesion molecule (N-CAM) as an antigen. Immunoreactivity of K9BYU to insect cell recombinant canine N-CAM was demonstrated by Western blotting using Sf9 insect cells transfected with the canine N-CAM gene. In Western blotting against canine brain tissue, K9BYU detected three isoforms of N-CAM that correspond to three major isoforms of human and mouse N-CAM (N-CAM-120, -140, and -180). From these results, K9BYU was considered to be a useful tool for research of canine N-CAM.

Genomic organization of the T-cell receptor gamma gene and PCR detection of its clonal rearrangement in canine T-cell lymphoma/leukemia.

Because the T-cell receptor gamma (TCRgamma) gene is rearranged at an early stage of T-cell development in both TCRalphabeta and TCRgammadelta lineages, it has been preferentially targeted to detect T-cell clonality in human lymphoma/leukemia. We isolated 22 independent cDNA clones encoding canine TCRgamma and the following analysis of nucleotide sequences using the dog genome database revealed that the canine TCRgamma locus contains at least four repertories of variable genes that can be organized into two distinct subgroups and six repertories of joining genes belonging to two distinct subgroups according to the nucleotide sequence similarity. The findings allowed us to design PCR primers that were directed to the conserved or specific nucleotide sequences for each subgroup of variable and joining genes. By using four different combinations of primers, a PCR-based analysis was performed on cell samples collected from T-cell lymphoma/leukemia and B-cell lymphoma cases and hyperplastic and normal lymph nodes. All cell samples from 11 T-cell malignancy cases exhibited clonal amplification by two out of four primer combinations. This finding was considered to be valuable in PCR-based analysis for detecting T-cell clonality in canine lymphoma/leukemia.

Light-chain multiple myeloma in a cat.

A diagnosis of light-chain multiple myeloma was made in an 11-year-old male American Shorthair cat. The cat showed atypical plasma cell infiltration in the bone marrow, biclonal gammopathy caused by polymerization of myeloma protein (M-protein), and Bence-Jones proteinuria. The M-protein in the serum of the cat was analyzed by using 12% sodium dodeyl sulfate (SDS) polyacrylamide gel electrophoresis with Coomassie brilliant blue staining. An intense band with a size of 27 kDa, the size of the immunoglobulin light chain, was clearly observed, whereas the band corresponding to the immunoglobulin heavy chain (59 kDa) was undetectable. The 27-kDa band was confirmed to be an immunoglobulin light chain by Western blotting by using antibodies for feline immunoglobulin. These data suggested that the neoplastic plasma cells produce light chain only, leading to the diagnosis of light-chain multiple myeloma in the cat.

Blastic natural killer cell leukaemia in a dog--a case report.

A case of canine non-T, non-B lymphoid leukaemia was determined to be of natural killer (NK) cell lineage by detecting specific expression of canine CD56 mRNA by reverse transcriptase polymerase chain reaction analysis. Although NK cells are usually considered to be morphologically large granular lymphocytes, the malignant NK cells in this case were agranular and blast-like, resembling human blastic NK cell leukaemia. The prognosis of human NK cell leukaemia is usually poor. In this case, the dog died 10 days after initial presentation, despite chemotherapy.

Comparison of dendritic cell-mediated immune responses among canine malignant cells.

Dendritic cell (DC) vaccination is one of the most attractive immunotherapies for malignancies in dogs. To examine the differences in DC-mediated immune responses from different types of malignancies in dogs, we vaccinated dogs using autologous DCs pulsed with keyhole limpet hemocyanin (KLH) and cell lysate prepared from squamous cell carcinoma SCC2/88 (SCC-KLH-DC), histiocytic sarcoma CHS-5 (CHS-KLH-DC), or B cell leukemia GL-1 (GL-KLH-DC) in vitro. In vivo inductions of immune responses against these tumor cells were compared by the delayed-type hypersensitivity (DTH) skin test. The DTH response against SCC2/88 cells were observed in dogs vaccinated with autologous SCC-KLH-DC, while the response was undetectable against CHS-5 and GL-1 cells in dogs vaccinated with autologous CHS-KLH-DC and GL-KLH-DC. Skin biopsies taken from DTH challenge sites were then examined for immunohistochemistry, and recruitment of CD8 and CD4 T cells was detected at the site where SCC2/88 cells were inoculated in dogs vaccinated with SCC-KLH-DC. By contrast, neither CD8 nor CD4 T cell infiltration was found at the DTH challenge site in the dogs vaccinated with CHS-KLH-DC or GL-KLH-DC. These findings may reflect that the efficacy of immune induction by DC vaccination varies among tumor types and that immune responses could be inducible in squamous cell carcinoma. Our results encouraged further investigation of therapeutic vaccination for dogs with advanced squamous cell carcinoma in clinical trials.

Chronic sleep fragmentation exacerbates amyloid ß deposition in Alzheimer's disease model mice.

Sleep fragmentation due to intermittent nocturnal arousal resulting in a reduction of total sleep time and sleep efficiency is a common symptom among people with Alzheimer's disease (AD) and elderly people with normal cognitive function. Although epidemiological studies have indicated an association between sleep fragmentation and elevated risk of AD, a relevant disease model to elucidate the underlying mechanisms was lacking owing to technical limitations. Here we successfully induced chronic sleep fragmentation in AD model mice using a recently developed running-wheel-based device and demonstrate that chronic sleep fragmentation increases amyloid ß deposition. Notably, the severity of amyloid ß deposition exhibited a significant positive correlation with the extent of sleep fragmentation. These findings provide a useful contribution to the development of novel treatments that decelerate the disease course of AD in the patients, or decrease the risk of developing AD in healthy elderly people through the improvement of sleep quality.

Neuronal expression of keratinocyte-associated transmembrane protein-4, KCT-4, in mouse brain and its up-regulation by neurite outgrowth of Neuro-2a cells.

One group of proteins that regulates neurite outgrowth and maintains neuronal networks is the immunoglobulin superfamily (IgSF). We previously identified a new member of the IgSF, keratinocyte-associated transmembrane protein-4 (KCT-4), by the signal sequence-trap method from primary cultured human keratinocytes. The KCT-4 mRNA has been found to be highly expressed in the adult human brain, although it is also distributed in various tissues. In the present study, to gain insight into the role of KCT-4 in the nervous system, we examined the expression profile and localization of KCT-4 mRNA in mouse brain. We also evaluated changes in KCT-4 mRNA expression in the differentiation of the neuroblastoma cell line Neuro-2a as the in vitro model of neurite outgrowth. KCT-4 mRNA was detected broadly in various regions of the adult mouse brain by RT-PCR. In situ hybridization revealed that it was expressed highly selectively by neurons but not by glial cells. Moreover, expression of KCT-4 mRNA was induced by neurite outgrowth of Neuro-2a. These data suggest that KCT-4 participates in the regulation of neurite outgrowth and maintenance of the neural network in the adult brain.

Identification of a c-kit exon 8 internal tandem duplication in a feline mast cell tumor case and its favorable response to the tyrosine kinase inhibitor imatinib mesylate.

The gain-of-function mutations within c-kit, a protooncogene encoding KIT, induce constitutive ligand-independent kinase activation and are important for the pathogenesis of mast cell proliferative disease in humans as well as in dogs. Despite the clinical importance of feline mast cell tumors, no mutation has been shown within the c-kit gene in cats. In the present report, we analyzed the c-kit nucleotide sequence in the case of a cat that showed systemic mastocytosis and mastocytemia. Within the c-kit cDNA prepared from the malignant mast cells, we identified an 12-bp internal tandem duplication at the region corresponding to exon 8, resulting in a four amino acid insertion between residues Thr418 and His419 within the fifth immunoglobulin-like domain of KIT. The cat underwent therapy with the kinase inhibitor imatinib mesylate (Gleevec) at a dose of 10mg/kg. The tumor masses greatly responded and were undetectable after 5 weeks of treatment. Correspondingly, the number of mast cells in the peripheral blood was markedly reduced. It is, therefore, considered that the internal tandem duplication within the domain contributes to the neoplastic transformation of mast cells in the cat by increasing KIT phosphorylation.

Efficient generation of canine bone marrow-derived dendritic cells.

Because of their unsurpassed potency in presenting antigens to naive T cells, dendritic cells are considered to be an important candidate in the development of immunotherapeutic strategies. Despite the high potential of dendritic cell-based immunotherapy, as a so-called dendritic cell vaccination, few clinical approaches using dendritic cell vaccination have been performed in the dog because of very limited information regarding the generation of canine dendritic cells and their functional properties. We therefore established a protocol for the efficient generation of dendritic cells from canine bone marrow cells using recombinant feline granulocyte-macrophage colony-stimulating factor and canine interleukin-4. Dendritic cells were generated efficiently: a yield of 1-9 x 10(6) cells per approximately 0.5 ml of canine bone marrow aspiration was achieved. These dendritic cells showed features shared with mouse and human dendritic cells: dendrite morphology, expression of surface markers MHC class II and CD11c, and up-regulation of molecules related to antigen presentation (MHC class II, B7-1, and B7-2) by activation with lipopolysaccharide. Moreover, the dendritic cells demonstrated phagocytic activity, processing activity of pinocytosed proteins, and activation of allogeneic T cells far more potent than that by macrophages. Our findings suggest that the bone marrow-derived dendritic cells are functional for the capturing and processing of antigens and the initiation of T cell responses.

Ultraviolet-B radiation upregulates expression of dectin-2 on epidermal Langerhans cells by activating the gene promoter.

Epidermal Langerhans cells (LC) belong to the antigen-presenting cell (APC) family of dendritic cells that can initiate antigen-specific immunogenic or tolerogenic responses. In mice, we have shown ultraviolet-B (UV-B) irradiation to induce long-lasting suppression (tolerance) of contact hypersensitivity responses by converting LC from immunogenic to tolerogenic APC. The C-type lectin receptor, dectin-2, expressed preferentially by LC and dendritic cells, has also been shown to be involved in inducing this form of UV-B-induced immunosuppression. These observations led us to question whether UV-B can modulate dectin-2 expression by LC. In ICR mice engineered to express the dectin-2 gene promoter linked to a luciferase reporter gene, we found broadband UV-B treatment in vivo to activate the promoter in LC. In wild-type C3H/HeN mice, we found such treatment in vivo to yield LC with increased dectin-2 expression at both mRNA and protein levels. Broadband UV-B treatment in vitro of bone marrow-derived dendritic cells from these mice also showed upregulated expression of dectin-2 mRNA. These findings lead us to conclude that broadband UV-B upregulates dectin-2 expression in LC by activating the dectin-2 gene promoter. Such amplification suggests that UV-B-induced immunosuppression may be due (at least in part) to augmented dectin-2 expression in LC.

Transcriptional regulation of dectin-2 promoter in transgenic mouse.

Despite a preeminent role of epidermal Langerhans cells (LC) in inducing primary immunity, application of gene-based modification to LC function is limited by lack of well-defined transcription regulatory units that can direct LC-specific gene expression. Previously we reported that the promoter activity of a 5'-flanking region of the dectin-2 gene (Dec2FR) is highly targeted to epidermal LC of transgenic mice bearing a Dec2FR-driven Luc gene. Using the mice, in which transcription activity of Dec2FR is measured by Luc assays, presently we characterized regulation of Dec2FR activity in leukocyte subpopulations under resting and activation status. Luc activity was highly variable in LC isolated from different skin areas and detected in other DC subset (dermal DC) but the levels were much lower than in resting LC. Activation of leukocytes markedly up-regulated Luc activity in all four subpopulations (CD11c+ splenic DC, Mac-1high peritoneal macrophages, splenic B220+ B cells, and CD3+ T cells). However, these levels remained lower than those in the resting and activated LC. These findings indicate that dectin-2 promoter activity remains targeted to epidermal LC even after activation of leukocytes, suggesting a high potential of Dec2FR to engineer LC-targeted gene expression to heighten efficacy of genetic vaccination and to manipulate phenotypes of preexisting immunity (Th1 vs. Th2).

Reconstruction of stratum corneum in organotypically cultured canine keratinocyte-derived CPEK cells.

The stratum corneum of epidermis is an essential barrier against the external environment and water loss. This study aimed to develop an organotypic culture model that targets the reconstruction of the stratum corneum using canine keratinocyte-derived CPEK cells. The CPEK cells cultured at the air-liquid interface became stratified and formed a stratum corneum-like layer on stratum spinosum- and stratum granulosum-like layers. The CPEK cells in the stratum granulosum-like layer expressed the cornified cell envelope (CCE)-related proteins loricrin and keratinocyte differentiation-associated protein. Organotypically cultured CPEK cells were considered to form a CCE at the stratum granulosum-like layer, allowing the formation of a stratum corneum-like layer. The organotypic culture of CPEK cells could be useful for studying the barrier function of canine stratum corneum.