The "Swiss roll": a simple technique for histological studies of the rodent intestine

The effect of soy isoflavones on the development of intestinal neoplasia in ApcMin mouse

Data from epidemiological studies suggest that isoflavones in soy may have a protective effect on the development of colon cancer in humans. Therefore, we have investigated whether soy isoflavones will inhibit intestinal tumour development in Apc(Min) mice. The mice were fed a Western-type high risk diet (high fat, low fibre and calcium) containing two different isolates of soy protein as a protein source. For the control and test groups this resulted in the administration of about 16 and 475 mg of total isoflavones per kg diet, respectively. As a positive control. a third group of mice was administered a low isoflavone diet supplemented with 300 ppm sulindac. No significant differences in the incidence, multiplicity, size and distribution of intestinal tumours were observed between Min mice fed low and high isoflavone-containing diets. However, a clear reduction in the number of small intestinal tumours was observed for the sulindac diet. Thus, in contrast to epidemiological studies, our results demonstrate that high amounts of soy isoflavones present in a Western-type high risk diet do not protect against intestinal tumour development in a relevant animal model such as the Min mice.

Differential susceptibility of inbred mouse strains to dextran sulfate sodium-induced colitis

Dextran sulfate sodium (DSS)-induced murine colitis represents an experimental model for human inflammatory bowel disease. The aim of this study was to screen various inbred strains of mice for genetically determined differences in susceptibility to DSS-induced colitis. Mice of strains C3H/HeJ, C3H/HeJBir, C57BL/6J, DBA/2J, NOD/LtJ, NOD/LtSz-Prkdc(scid)/Prkdc(scid), 129/SvPas, NON/LtJ, and NON.NOD-H2g7 were fed 3.5% DSS in drinking water for 5 days and necropsied 16 days later. Ceca and colons were scored for histological lesions based on severity, ulceration, hyperplasia, and area involved. Image analysis was used to quantitate the proportion of cecum ulcerated. Histological examination revealed significant differences among inbred strains for all parameters scored. In both cecum and colon, C3H/HeJ and a recently selected substrain, C3H/HeJBir, were highly DSS susceptible. NOD/LtJ, an autoimmune-prone strain, and NOD/LtSz-Prkdc(scid)/Prkdc(scid), a stock with multiple defects in innate and adoptive immunity, were also highly DSS susceptible. NON/LtJ, a strain closely related to NOD, was quite DSS resistant. The major histocompatibility (MHC) haplotype of NOD mice (H2g7), a major component of the NOD autoimmune susceptibility, was not crucial in determining DSS susceptibility, since NON mice congenic for this MHC haplotype retained resistance. C57BL/6J, 129/SvPas, and DBA/2J mice showed various degrees of susceptibility, depending upon the anatomical site. A greater male susceptibility to DSS-induced colonic but not cecal lesions was observed. In summary, this study demonstrates major differences in genetic susceptibility to DSS-induced colitis among inbred strains of mice. Knowledge of these strain differences in genetic responsiveness to acute inflammatory stress in the large intestine will permit design of genetic crosses to elucidate the genes involved.

Inflammatory bowel disease: an immunity-mediated condition triggered by bacterial infection with Helicobacter hepaticus

Inflammatory bowel disease (IBD) is thought to result from either an abnormal immunological response to enteric flora or a normal immunological response to a specific pathogen. No study to date has combined both factors. The present studies were carried out with an immunologically manipulated mouse model of IBD. Mice homozygous for the severe combined immunodeficiency (scid) mutation develop IBD with adoptive transfer of CD4+ T cells expressing high levels of CD45RB (CD45RB(high) CD4+ T cells). These mice do not develop IBD in germfree conditions, implicating undefined intestinal flora in the pathogenesis of lesions. In controlled duplicate studies, the influence of a single murine pathogen, Helicobacter hepaticus, in combination with the abnormal immunological response on the development of IBD was assessed. The combination of H. hepaticus infection and CD45RB(high) CD4+ T-cell reconstitution resulted in severe disease expression similar to that observed in human IBD. This study demonstrates that IBD develops in mice as a consequence of an abnormal immune response in the presence of a single murine pathogen, H. hepaticus. The interaction of host immunity and a single pathogen in this murine system provides a novel model of human IBD, an immunity-mediated condition triggered by bacterial infection.

Quercetin prevents UV-induced local immunosuppression, but does not affect UV-induced tumor growth in SKH-1 hairless mice

Ultraviolet is thought to induce skin tumors by its dual activity as a mutagenic agent and a suppressor of cell-mediated immunity. In the present study the effects of quercetin, a flavonoid-containing compound, on carcinogenesis and immunosuppression were studied in SKH hairless mice exposed to suberythemal doses of UV for up to 17 weeks. It was found that quercetin did not affect the onset or growth of non-melanoma skin tumors resulting from UV exposure. In contrast, it prevented the suppression in contact hypersensitivity (CHS) to picryl chloride induced by UV. The mechanism of this prevention might be explained by the observation that the decreased number of epidermal Langerhans' cells is partly prevented by the quercetin. Quercetin did not alter the effects of UV in increasing numbers of spleen and lymph node cells, only partly in decreasing the CD8-positive cells in spleen cell populations and decreasing the lymphoproliferative response of spleen cells to the mitogens concanavalin A and phytohemagglutinin. Thus oral quercetin did not prevent UV-induced carcinogenesis although it restored the skin-associated CHS response probably by protecting the antigen-presenting cells in the skin.

Subacute toxicity of ergometrine maleate in rats

Ergot alkaloids, produced by the fungus Claviceps purpurea, are found in small amounts in foodstuffs. The human disease ergotism, caused by high intake of ergot alkaloids, is well known; however, little is known about the toxicity of these compounds. The subacute toxicity of an ergot alkaloid, ergometrine maleate, was therefore studied. Sprague-Dawley rats were treated with 0, 2, 10, 50 and 250 mg ergometrine maleate/kg diet for 4 wk. Plasma glucose levels were decreased in females at 50 and 250 mg/kg. Thyroxin levels were decreased at 50 (males only) and 250 mg/kg. At the high dose level, organ weights of heart, liver, ovaries and kidneys were increased. In male rats a slight dose-related increase in the incidence of enlarged mediastinal lymph nodes and, to some extent, of enlarged parathymal lymph nodes, was seen. Histopathological examination revealed evidence of increased glycogen storage in the liver of animals treated with 250 mg/kg. The no-observed-effect level in this study was 10 mg/kg.

Cadmium and atherosclerosis in the rabbit: reduced atherogenesis by superseding of iron?

This study evaluated the effect of dietary cadmium (Cd) on atherosclerosis in the rabbit. Cholesterol was added to the diet to initiate and/or accelerate atherogenesis. Cd was added to the diet at two dose levels. Uptake of Cd was 55 micro gram/kg body weight (BW)/day at the low dose level and 1350 micrograms/ kg BW/day at the high dose level. Five groups of rabbits were fed five different diets for 9 months: (1) basal diet without additional constituents; (2) background diet, which was basal diet to which cholesterol had been added; (3) the low-dose level Cd diet, which was background diet to which 2 mg Cd/kg had been added; (4) high-dose level Cd diet, which was background diet to which 50 mg Cd/kg had been added; and (5) basal diet to which 50 mg Cd/kg had been added. Dietary cholesterol increased blood total leucocyte count, serum and liver total cholesterol concentrations, serum total bilirubin concentration, low-density lipoprotein vitamin E concentration and induction of atherosclerotic plaques in the aorta and coronary arteries. Cd in the diet increased liver and kidney Cd concentrations in a dose-dependent way, decreased prothrombin time and temporarily increased urea and creatinine clearances. Slight kidney damage was induced by Cd only in animals fed the high-dose level Cd diet (with or without cholesterol). Dietary Cd partly counteracted the dietary cholesterol-induced increases of serum and liver total cholesterol concentrations, and tended to reduce plaque formation in the aorta. Dietary Cd in rabbits fed cholesterol-containing diets influenced cholesterol metabolism and tended to decrease atherosclerosis in a dose-related fashion. This is in contrast with limited epidemiological human data. Dietary Cd also decreased serum ferritin concentration and increased serum transferrin concentration. Free iron concentration is associated with myocardial infarction in man and augments the development of atherosclerosis in rabbits. It is concluded that the observed reduction in atherogenesis is related to dietary Cd-induced changes in cholesterol metabolism, increased rheology of blood and/or, most likely, reduced free iron concentration.

Spontaneous, heritable colitis in a new substrain of C3H/HeJ mice

BACKGROUND/AIMS

C3H/HeJ mice at the Jackson Laboratory have periodically been culled because of the occurrence of soft feces, perianal ulceration, and right-sided colitis. No pathogens have been isolated. The goal of the current study was to establish a substrain with a high incidence of this disease.

METHODS

Affected male and female C3H/HeJ mice were bred. The clinical, pathological, microbiological, and genetic features of 216 mice of the resulting pedigree were characterized.

RESULTS

A severely affected female crossed with a normal male resulted in a new substrain, denoted C3H/HeJBir, with a high incidence of right-sided colitis. Histologically, lesions occurred primarily in the cecum and proximal colon, characterized by acute and chronic inflammation, crypt abscesses, ulcerations, regenerative hyperplasia, and submucosal scarring. Such colitis peaked at 3-6 weeks; however, similar disease was found sporadically in animals more than 1 year of age. Small lesions at the anorectal junction were common throughout life. An extensive search for pathogens was negative. Genetic analysis of C3H/HeJBir mice suggested that the disease was inherited as a quantitative trait.

CONCLUSIONS

C3H/HeJBir mice develop a spontaneous, heritable form of idiopathic inflammatory bowel disease and will be a valuable resource for genetic and immunologic studies of this disease.

Histopathology of the immune system as a tool to assess immunotoxicity

Immunotoxicology studies the undesired effects of interactions between xenobiotics and the immune system, mainly in toxicity experiments in rodents. The histopathology of the lymphoid organs is a cornerstone in such studies. In this review we describe practical aspects of sampling lymphoid organs and subsequent tissue processing and application of conventional and advanced histologic techniques. Thereafter, some aspects of proper reading and interpretation of histopathology is discussed, in relation to modifying factors such as age, sex, strain of animals, housing conditions, and nutritional status. These factors can substantially confound the outcome and interpretation of experiments, due to the highly dynamic characteristics of the immune system. Immunotoxicity tests are normally performed in a tiered approach. We describe the screening tier in the rat species that has been developed in the National Institute of Public Health and Environmental Protection, Bilthoven, The Netherlands, and illustrate the value of histopathology by an example of immunotoxicity testing of pesticides. Subsequently, the tiered approach in the mouse species followed by the National Toxicology Program in the USA, is described. In the evaluation of chemicals with suspected immunotoxic potential using this approach, histopathology proved to be less sensitive in 'flagging' immunotoxicity. This may be related to the lower doses that are applied in this toxicity design, because at higher doses histopathology is a sensitive indicator of toxicity. A global description of pathologic alterations after toxic insult is given, followed by representative examples taken from immunosuppressive drugs--the cytostatic agent 5-fluorouracil, and drugs interfering with cytokine expression, namely, Cyclosporin A, FK-506, and Rapamycin.

Phenotype of intraepithelial lymphocytes in euthymic and athymic mice: implications for differentiation of cells bearing a CD3-associated gamma delta T cell receptor

This study was carried out to determine the exact phenotype of intraepithelial lymphocytes (IEL) in euthymic and athymic nude mice. The phenotype of IEL in euthymic and athymic mice is mainly CD3+CD8+. However, based on Thy-1- and CD3-associated receptor expression we can subdivide the CD3CD8 population into different subpopulations in euthymic and athymic mice. In euthymic and athymic mice several CD3CD8 populations can be defined. One population expressing Thy-1 and the T cell receptor (TcR) alpha beta is absent in athymic mice. Two other CD3+CD8+ populations can be detected in euthymic and athymic mice. Based on Northern blot and flow cytometric analysis we have to conclude that these populations express the CD3-associated TcR gamma delta. One of the TcR gamma delta-expressing populations also expresses Thy-1 at low surface density. This is in contrast to the CD3CD8 population expressing the TcR alpha beta, which expresses Thy-1 at high surface density. There are also, however, especially in athymic nude mice, significant numbers of CD3-CD8+ cells present with the same localization as IEL. The function of these cells is yet unknown. Using a probe for the delta chain we have shown that IEL preferentially express 2-kb mRNA, while nearly no delta chain 1.7-kb mRNA is expressed by these cells. This is in contrast to delta mRNA in thymocytes. Equal quantities of the 1.7- and 2.0-kb delta chain mRNA species were found in RNA isolated from thymocytes. The results imply that CD3+CD8+ intestinal IEL expressing the CD3-associated TcR gamma delta can differentiate in absence of the thymus and represent a thymus-independent lineage of cells bearing this receptor.

T-cell development during ageing in congenitally athymic (nude) rats

We studied the thymus-dependent immune system in congenitally athymic (nude) rats of the WAG (RT-1u) strain, at the ages of 2, 3, 5, 9, and 17 months. This included the histology of spleen, lymph nodes, and Peyer's patches, immunohistochemistry on tissue sections, and immunocytology on cell suspensions using a panel of monoclonal antibodies to T-lymphocyte subpopulations, in vitro mitogen responsiveness, and in vivo responsiveness to ovalbumin immunization. The results were compared with those in euthymic immunocompetent littermates of the same age. The cell marker analysis, especially in nude animals, was hampered by the staining of non-T cells by some of the antibodies (staining of putative macrophages, natural killer cells, cells of B-lymphocyte lineage, and of myeloid lineage). Despite this, with age an increase in cells with these markers was observed; for instance, in spleen suspensions, cells labelled by the pan-T reagent MRC OX-19 increased from 5% at 2 months to 19% at 17 months (value in euthymic animals 34%). In the other assays too a gradual increase of T-cell reactivity with age was observed, from almost absent in 2- and 3-month-old nude rats to values in 17-month-old animals of about half the level found in euthymic rats. However, none of the nude animals responded to ovalbumin immunization. These results indicate that in nude animals processes occur which compensate for the absent intrathymic T-cell generation. This applies in particular to changes in T-cell phenotype and mitogen responsiveness, but not to antigen responsiveness.

Effects of feeding stannous chloride on different parts of the gastrointestinal tract of the rat

The effects of feeding inorganic tin on the gastrointestinal tract were examined in rats. Three groups of male weanling Wistar rats were fed a diet to which 0, 250, or 500 ppm Sn2+ had been added as SnCl2. A fourth group was subjected to feed restriction by pair feeding with the 500-ppm group. Comparison of the data from the tin-fed groups with both the control and the reduced diet groups allowed discrimination between effects of reduced feed intake and Sn2+ effects. Independent of the reduced feed intake, Sn2+ affected hemoglobin concentration in the blood and several small intestine parameters. Total length of the small intestine, as well as absolute and relative weights, was increased. An increase was also observed in the migration of epithelial cells along the villus, as revealed by [3H]thymidine incorporation and autoradiography in rats fed 900 ppm Sn2+ for 4 weeks. Stereo-light microscopy and scanning electron microscopy revealed the formation of ridge-like villi due to Sn2+ feeding and a decreased number of villi per unit surface. These data suggest that an increase in cell turnover in the small intestine, due to Sn2+, was responsible for these changes.

In vivo biological effect of allogeneic cultured thymic epithelium on thymus-dependent immunity in athymic nude rats

We have extended our previous study of induction of T-lymphocyte immunocompetence in athymic nude rats by cultured epithelium (CTE) of syngeneic origin to that by CTE of allogeneic origin. Immune responsiveness (IgG-class antibody and delayed-type hypersensitivity) after ovalbumin immunization is detectable by 4-6 weeks after transplantation. However, the antibody appears at a slower rate when compared with heterozygous immunocompetent littermates. Seven weeks after transplantation phytohaemagglutinin responsiveness of spleen cells is detectable, and in T-dependent areas of lymphoid organs lymphocytes with helper and non-helper T-cell phenotype are present, but at lower levels than those in heterozygous immunocompetent littermates. Levels comparable to that of immunocompetent rats are reached about 20 weeks after transplantation. Since CTE contains thymocytes, control experiments consisted of transplantation with high numbers of allogeneic freshly isolated thymocytes in athymic nude rats. These animals showed IgG-class antibody formation after ovalbumin immunization, but at lower levels than CTE-treated rats, and were almost negative in T-cell immunocompetence assessed in the other assays. We conclude that CTE of allogeneic origin induces T-cell immunocompetence in athymic nude rats to the level of heterozygous immunocompetent littermates. This study adds to the rationale of CTE transplantation applied in treatment of thymic dysfunction.

Toxicity of bis(tri-n-butyltin)oxide in the rat. I. Short-term effects on general parameters and on the endocrine and lymphoid systems

Male and female Wistar rats were fed bis(tri-n-butyltin)oxide (TBTO) at 0, 5, 20, 80, or 320 mg/kg diet for 4 weeks. Clinical signs and decreases in feed and water consumption were observed in the 80 and 320 mg/kg groups. The serum transferase activities (alanine amino transferase and aspartate amino transferase were increased at 20 (males only), 80, and 320 mg/kg. The serum glucose and liver glycogen concentrations were lowered in the 320 mg/kg group. At 80 and 320 mg/kg the serum IgG level was reduced and IgM level was increased. Compared to controls the mean relative weight of the thymus was decreased at 20 (males), 80, and 320 mg/kg. In the groups receiving 80 or 320 mg/kg microcytic anemia was found. The white blood cell counts were decreased, due to the reduction in the number of lymphocytes in the 80 (males) and 320 mg/kg groups. The concentration of neutrophilic granulocytes was increased in the highest dose group. Histopathologic effects included a dose-related lymphocyte depletion of thymic cortex and of T lymphocytes in spleen and mesenteric lymph nodes. In the spleen also depletion of iron stores was found, and in the medullary sinuses of mesenteric lymph nodes, rosettes of erythrocytes were found around mononuclear cells; the occurrence of rosettes increased with dose from 5 to 80 mg/kg, and appeared to be the most sensitive parameter. A low incidence of areas of liver necrosis with inflammatory reaction and bile duct hyperplasia was found in the 320 mg/kg group. A viral or bacterial etiology could be demonstrated for these liver lesions, but they appeared associated with TBTO-induced ulcerative inflammation of the common bile duct as shown in an additional study. In 6-week studies exposure of male weanlings to the 0, 20, and 80 mg/kg diets, the serum insulin concentration in the treated groups was decreased, although the response to glucose challenge was unaffected. The serum thyroxin and thyrotropin (TSH) concentrations were reduced, whereas the luteinizing hormone (LH) concentration was increased in the 80 mg/kg group. The concentrations of follicle-stimulating hormone (FSH) and corticosterone were not changed. The release of LH and FSH was enhanced in the 80 mg/kg group and a tendency toward reduced release was found for TSH. Using immunocytochemistry a dose-related reduction was found in the number and staining intensity of TSH-producing cells in the pituitary, correlating with histopathologically decreased activity of the thyroid.(ABSTRACT TRUNCATED AT 400 WORDS)

The athymic nude rat. IV. Immunocytochemical study to detect T-cells, and immunological and histopathological reactions against Trichinella spiralis

The anti-parasite response was investigated after oral infection of athymic nude (rnu/rnu) rats and heterozygous (+/rnu) littermates with 1000 muscle larvae of Trichinella spiralis. No IgM, IgG and IgE antibodies were detected in serum of rnu/rnu rats. Expulsion of adult worms from the small intestine was prolonged (worms were nearly all expelled at days 14 and 91 in +/rnu and rnu/rnu rats respectively). The yield of muscle larvae in the carcasses of nude rats at day 91 was 33 times higher than in +/rnu rats. In contrast to the strong inflammatory reaction in the parasitized tongue of +/rnu rats, no infiltration was observed in rnu/rnu rats. Using an immunoperoxide method with monoclonal anti-rat T-cell antibody, no T cells were identified in spleen, mesenteric lymph node and Peyer's patches. These data support earlier studies that the nude rat lacks functional T cells. As the counts of connective tissue mast cells (CTMC), intestinal mast cells (IMC) and globule leucocytes (GL) in small intestine of uninfected rnu/rnu rats were equal or higher than in +/rnu rats, it is concluded that the origin of these cells is thymus-independent. In contrast to +/rnu rats, infection of rnu/rnu rats induced no increase of CTMC, IMC or GL. Thus, these cells depend on T cells to undergo proliferation. Finally, results of this study were inconclusive whether IMC are precursors for GL, or that they represent independent cell populations.