Masahiro Morimoto

Less sensitivity for late airway inflammation in males than females in BALB/c mice

Several studies have investigated allergic airway inflammation, a T helper 2 (Th2)‐type immune response, using a mouse model of asthma. At present, however, no reports have described sex differences in the sensitivity of late airway inflammation (LAI). The LAI induced by ovalbumin in adult BALB/c mice was compared in males and females or sham‐operated males and castrated males. The males showed less severe bronchial‐bronchiolar inflammation with infiltration of eosinophils and lymphocytes and lower content of such cells in bronchoalveolar fluid than the females. Moreover, interleukin‐4 (IL‐4) mRNA expression levels in splenic cells were lower in the males than in the females. Castrated males performed like the females. Moreover, when compared with the sham‐operated males, the castrated males showed lower testosterone levels in the blood. The present results suggest that less sensitivity for LAI in the males may be because of the decreased Th2 cell responses compared with the females. Moreover the testosterone, at least in part, may be responsible for the decreased Th2 cell responses in males in vivo.

Possible Involvement of IL‐12 in Reovirus Type‐2‐Induced Diabetes in Newborn DBA/1 Mice

This study extends our previous observations that the reovirus type‐2(Reo‐2) can induce autoimmune insulitis, which may be mediated by T‐helper(Th)1‐dependent mechanisms, resulting in diabetes in newborn DBA/1 mice. In this study mRNA expression for Th1‐related cytokines including Th1 and Th2 cytokines in splenic cells was examined by reverse transcriptase polymerase chain reaction (RT–PCR) in relation to the development of insulitis. Furthermore, the effect of monoclonal antibody (MoAb) against interleukin (IL)‐12(p40) on the development of insulitis and the mRNA expression in the splenic cells was examined. The mRNA expression for IL‐12(p40), IL‐18, and interferon (IFN)‐γ, but not IL‐5, increased in the spleen in parallel with the development of insulitis. The treatment with MoAb to IL‐12(p40) reduced the insulitis with diabetes which was associated with a decrease in the mRNA expression for IL‐12(p40), IL‐18 and IFN‐γ, and an increase of IL‐4 mRNA expression in the spleen. The present study suggested that Th1‐dominant systemic immune responses, being responsible for the development of autoimmune insulitis, might be induced by IL‐12‐induced and IL‐18‐activated mechanisms.

Superficial necrolytic dermatitis associated with extrapancreatic glucagonoma in a dog.

An 11-year-old Shih Tzu presented with crusting and erythema, mainly on the abdomen and the root of the tail. Based on histopathological findings, blood examinations and necropsy findings, the condition was diagnosed as superficial necrolytic dermatitis associated with a glucagon-secreting extrapancreatic neuroendocrine tumour. Gross necropsy revealed tumour invasion into the spleen, liver, adrenal glands and mesenteric lymph nodes. Immunohistochemical analysis of the neoplastic cells revealed that the tumour was a glucagonoma, consistent with earlier findings of persistent glucagonaemia and hypoaminoacidaemia.

Nematode Infection in Alymphoplasia (aly) Mice: Worm Species-Dependent Differential Effect of Defects of the Gut-Associated Lymphatic Tissue System

Mice homologous for the alymphoplasia mutation (aly) show the systemic absence of secondary lymphoid tissues, with disorganized splenic architecture, including the absence of the germinal centre and follicular dendritic cells. In this study, we examined the influence of defects of gut‐associated lymphoid tissue (GALT), such as Peyers patches and the mesenteric lymph nodes, on the host response to helminth infection in aly/aly mice. The present study showed that most of the worms were expelled by day 7 after Nippostrongylus brasiliensis infection in both control aly/+ and aly/aly mice. In aly/aly mice, the number of peripheral blood eosinophils, intestinal goblet cells and mucosal mast cells were increased by N. brasiliensis infection in aly/aly mice to the same level as in the controls. Conversely, aly/aly mice developed more severe Heligmosomoides polygyrus infections than control aly/+ mice, as demonstrated by increased faecal egg counts, with reduced immune responses such as the numbers of intestinal goblet cells and mucosal mast cells. These results suggested that the dependency of GALT in activation of Th2 responses against gastrointestinal nematodes was different depending on the species of nematode.

Detection of centrosome amplification as a surrogate marker of dysfunction in the p53 pathway -p53 gene mutation or MDM2 overexpression.

Abstract In human and canine cancers, the inactivation of p53 protein as well as p53 gene mutation and MDM2 overexpression result in centrosome amplification that in turn contributes to chromosomal instability. To explore the usefulness of the detection of centrosome amplification as a surrogate marker of dysfunction in the p53 pathway, we systematically analysed centrosome amplification, p53 overexpression, p53 gene mutation and MDM2 overexpression in canine tumours. Centrosome amplification was detected in 16 of 51 (31%) naturally developing tumours in dogs. All the tumour specimens with aberrations in the p53 pathway, including p53 overexpression, p53 gene mutation or MDM2 overexpression, showed centrosome amplification, suggesting that the detection of centrosome amplification could serve as a preliminary surrogate marker of dysfunction in the p53 pathway.

Calreticulin expression in neoplastic versus normal dog mammary glands: a cDNA subtraction-based study.

This is the first report describing the expression of canine calreticulin (cCRT) in canine mammary gland tumour (MGT). Using cDNA subtraction method, it is found that mRNAs of CRT, cathepsin A, ovostatin, and lactotransferrin were differentially expressed in mammary adenocarcinoma as compared to hyperplasia, both of which were obtained from the dog. Furthermore, the mRNA expression levels of CRT and cathepsin A were significantly higher in canine MGT samples than in nontumour samples. In contrast, immunohistochemical studies have indicated that the expression of cCRT protein found to be detected in most of mammary gland tissues and was not correlated to the types of canine MGTs. Furthermore, cCRT was molecularly cloned, and the amino acid sequence of cCRT was found to be very similar to those of other species. Further studies are required to elucidate additional roles of cCRT in canine MGT.

Lactic Dehydrogenase Virus Infection Inhibits Allergic Eosinophil Reaction and IL–5 Gene Expression in vivo

The effects of lactic dehydrogenase virus (LDV) infection on allergic eosinophil reaction and IL–5 gene expression were studied. LDV infection suppressed antigen–induced eosinophil recruitment into the peritoneal cavity in sensitized mice. The elevation of IL–5 gene expression in the spleen and mesenteric lymph nodes 6 h after ovalbumin challenge was significantly suppressed in LDV–infected mice compared with uninfected (control) mice. The expression of the interferon–γ and IL–2 genes in the spleen, but not in mesenteric lymph nodes, was significantly suppressed in LDV–infected mice compared with control mice. The present results suggest, that suppression of IL–5 gene expression by LDV infection may not be mediated by a mutual inhibitory mechanism between Th1 and Th2 cells.

Expression of Stem Cell Factor in Feline Mast Cell Tumour

Stem cell factor (SCF) is a ligand of the molecule Kit, which is expressed in mast cells and is important for mast cell proliferation, migration and survival. Mast cell tumours (MCTs) are associated with mutations of c-kit, a proto-oncogene encoding the Kit protein. In this study, we examined SCF expression in 23 samples of feline MCTs. SCF expression was detected in 10 cutaneous MCTs and a case of splenic mastocytosis. In the cutaneous MCTs, SCF-positive tumour cells were located at the margins. Kit was expressed in eight of the 10 cutaneous cases of SCF-expressing MCTs. In these cases, Kit-positive cells were located near to SCF-positive cells, and SCF/Kit double-positive tumour cells were found. Ki67-positive tumour cells were not found near to SCF-positive cells. These results suggest that SCF autocrine/paracrine mechanisms are involved in the expansion of cutaneous MCTs, but not in tumour proliferation.