Protein calorie restriction affects nonhepatic IGF-I production and the lymphoid system: studies using the liver-specific IGF-I gene-deleted mouse model

Nutritional status is a critical factor that modulates the responsiveness of the liver to GH and the resulting production of endocrine (mostly liver-derived) IGF-I. Using a conditional Cre/lox P system, we have established a liver-specific IGF-I-deficient mouse model. Despite the reduction in the circulating IGF-I (75%), the growth parameters are normal, except for the reduced spleen size, providing a unique model to study the effect of protein restriction on the autocrine/paracrine GH/IGF-I axis. To determine the effects of protein calorie malnutrition on the spleen, liver-specific IGF-I-deficient mice were assigned to one of four isocaloric diets, differing in the protein content (20, 12, 4, and 0%), for a period of 10 d. A low protein intake decreased the nonhepatic IGF-I secretion into the circulation, whereas it caused an increase in the level of circulating GH. This supports the view that nonhepatic IGF-I production contributes to circulating IGF-I levels. The lack of dietary protein led to an up-regulation of GH and IGF-I receptors expression in the spleen, whereas the IGF-I mRNA remained unchanged, as was demonstrated by flow cytometry and ribonuclease protection assay. B lymphocytes seem to be responsible for the up-regulated GH/IGF-I receptor expression. Northern blot analysis showed an up-regulation of IGF-binding protein-3 mRNA levels, which suggests that the protein deprivation may lead to an increased sequestration of circulating or locally synthesized IGF-I. These results support the hypothesis that the splenic GH/IGF-I axis responds to the nutritional stress caused by a low protein intake, to maintain the tissue homeostasis.

The immunosuppressive effects of chronic morphine treatment are partially dependent on corticosterone and mediated by the mu-opioid receptor

Wild-type and mu-opioid receptor knockout (MORKO) mice were used to investigate the role of corticosterone (CORT) and the mu-opioid receptor (MOR) in chronic morphine-mediated immunosuppression. We found that although plasma CORT concentrations in CORT infusion (10 mg/kg/day) and morphine-pellet implantation (75 mg) mice were similar (400-450 ng/ml), chronic morphine treatment resulted in a significantly higher (two- to threefold) inhibition of thymic, splenic, and lymph node cellularity; inhibition of thymic-lymphocyte proliferation; inhibition of IL-2 synthesis; and activation of macrophage nitric oxide (NO) production when compared with CORT infusion. In addition, results show that the inhibition of IFN-gamma synthesis and splenic- and lymph node-lymphocyte proliferation and activation of macrophage TNF-alpha and IL-1beta synthesis occurred only with chronic morphine treatment but not with CORT infusion. These morphine effects were abolished in MORKO mice. The role of the sympathetic nervous system on morphine-mediated effects was investigated by using the ganglionic blocker chlorisondamine. Our results show that chlorisondamine was able to only partially reverse morphine's inhibitory effects. The results clearly show that morphine-induced immunosuppression is mediated by the MOR and that although some functions are amplified in the presence of CORT or sympathetic activation, the inhibition of IFN-gamma synthesis and activation of macrophage-cytokine synthesis is CORT-independent and only partially dependent on sympathetic activation.

Endotoxin potentiation of trichothecene-induced lymphocyte apoptosis is mediated by up-regulation of glucocorticoids

Exposure to bacterial endotoxin (lipopolysaccharide, LPS) is quite common and may increase human susceptibility to chemical-induced tissue injury. The purpose of this study was to identify mechanisms by which LPS potentiates lymphoid tissue depletion in B6C3F1 mice exposed to the common food-borne trichothecene mycotoxin, vomitoxin (VT). As demonstrated by DNA fragmentation and flow cytometric analysis, apoptosis in thymus, Peyer's patches, and bone marrow was marked in mice 12 h after administering Escherichia coli LPS (0.1 mg/kg body wt ip) concurrently with VT (12.5 mg/kg body wt po), whereas apoptosis in control mice or mice treated with either toxin alone was minimal. Based on observed increases in tumor necrosis factor-alpha (TNF-alpha) and interleukin (IL)-6 serum concentrations following LPS and VT cotreatment, the roles of these cytokines in apoptosis potentiation were assessed. Injection with rolipram, an inhibitor of TNF-alpha expression, or use of IL-6 knockout mice was ineffective at impairing thymic apoptosis induction by the toxin cotreatment, suggesting that these cytokines did not mediate LPS potentiation. Toxin cotreatment increased splenic cyclooxygenase-2 mRNA expression, suggesting possible involvement of prostaglandins in apoptosis. However, indomethacin, a broad spectrum inhibitor of cyclooxygenases, failed to block thymus apoptosis. Toxin cotreatment increased serum corticosterone and, furthermore, RU 486, a glucocorticoid receptor antagonist, significantly abrogated apoptosis in thymus, Peyer's patches, and bone marrow following LPS + VT exposure. The results presented herein and the known capacity of glucocorticoids to cause apoptosis indicate that hypothalamic-pituitary-adrenal axis plays a key role in LPS potentiation of trichothecene-induced lymphocyte apoptosis.

Effects of FTY720 in MRL-lpr/lpr mice: therapeutic potential in systemic lupus erythematosus

OBJECTIVE To examine the effects of a novel immunosuppressant, FTY720, on hematolymphoid cells and the clinical course of MRL-lpr/lpr (MRL/lpr) mice genetically predisposed to systemic lupus erythematosus (SLE).

METHODS

Apoptosis of hematolymphoid cells was determined in vitro by FACScan after staining with propidium iodide or merocyanine 540. From 4 months of age, 15 female MRL/lpr mice received oral administration of 2 mg/kg each of FTY720, methylprednisolone (mPSL), or vehicle, 3 times per week. Therapeutic efficacy was evaluated by levels of anti-dsDNA antibodies in serum and the survival rate. In parallel, T cell proliferation and secretion of interleukin 2 (IL-2) induced by anti-CD3, phenotypes of the spleen, lymph node and bone marrow cells, as well as immunohistochemistry of the kidney, were examined in vitro.

RESULTS

FTY720 at 2 microM induced apoptosis in more than 70% of double negative (CD4-/CD8-) T cells from the spleen of MRL/lpr mice in vitro. Oral FTY720 was tolerated well with no apparent side effects. FTY720 treated and control mice gained weight at an identical pace through to 9 months of age. FTY720 significantly suppressed the production of anti-dsDNA antibodies (FTY720 vs control: 1739 +/- 898 U/ml vs 410 +/- 356 U/ml at 8 months of age; p < 0.05) and reduced the deposition of IgG in glomeruli compared to control animals. At 9 months of age, the survival rate in the FTY720 treated mice was 86.9% compared to 33.0% in controls (p < 0.01). FTY720 decreased the number of double negative T cells from the spleen and lymph nodes in vivo, and increased T cell proliferation and IL-2 secretion induced by anti-CD3 stimulation in vitro.

CONCLUSION

FTY720 suppressed the development of autoimmunity and prolonged the lifespan of female MRL/lpr mice. Suppression of autoimmunity, at least in part, may have resulted from an apoptogenic potential of FTY720. Hence, it could be useful for primary or adjunctive therapy of human SLE.

Spinosad insecticide: subchronic and chronic toxicity and lack of carcinogenicity in Fischer 344 rats

Spinosad is an insecticide derived from a naturally occurring bacterium via fermentation. The toxicity of spinosad was characterized in subchronic and chronic toxicity/oncogenicity studies conducted according to standard toxicology regulatory guidelines. Subchronic toxicity was evaluated in groups of 10 Fischer 344 rats/sex given feed containing 0, 0.05, 0.1, 0.2, or 0.4% spinosad (Study 1) or 0, 0.003, 0.006, 0.012, or 0.06% spinosad (Study 2) for 13 weeks. Lower body weights and increased mortality occurred in rats given 0.4% spinosad. Microscopic effects were observed in the adrenal glands, liver, lymphoid cells, reproductive tissues, kidney, thyroid, stomach, lung, and skeletal muscle of rats given > or = 0.05% spinosad, and consisted primarily of vacuolation of cells; however, degenerative, regenerative, and/or inflammatory changes were also noted in some tissues. Vacuolation within a number of tissues was ultrastructurally characterized by an increase in size and number of lysosomes that contained extensive membranous whorls consistent with phospholipidosis. The no observed effect level (NOEL) in the 13-week studies was 0.012% (24 mg/kg/day) spinosad. Chronic toxicity and oncogenicity were evaluated in groups of 60 Fischer 344 rats/sex given feed containing 0, 0.005, 0.02, 0.05, or 0.1% spinosad for up to 2 years. Rats given 0.1% spinosad for 1 year had microscopic effects similar to those observed in the subchronic studies. Vacuolation and inflammation of the thyroid gland also occurred in rats given 0.05% spinosad for 1 year. Excessive mortality occurred in rats from the oncogenicity study given 0.1% spinosad by 21 months, and surviving rats were euthanized because the maximum tolerated dose had been exceeded. Rats given 0.05% spinosad for 2 years had vacuolation and/or inflammation involving the thyroid, lymphoid tissue, and lung. Rats given 0.05% spinosad had similar numbers of neoplasms as control rats, indicating that spinosad was not carcinogenic at dose levels up to 0.05%. The NOEL at 2 years was 0.005% (2.4 mg/kg/day) spinosad.

Cetirizine decreases interleukin-4, interleukin-5, and interferon-gamma gene expressions in nasal-associated lymphoid tissue of sensitized mice

Although the action of cetirizine dihydrochloride (cetirizine), a potent histamine H1 receptor antagonist, has been well known, its effect on the cytokine profiles in the nasal immune inductive site has not been elucidated yet. We studied the effect of cetirizine on the cytokine profiles in the nasal-associated lymphoid tissue (NALT), which is a principal mucosal lymphoid tissue of the respiratory tract in rodents. Two different doses of cetirizine were given intraorally for 5 days before the nasal challenge of ovalbumin in sensitized mice. The sensitized group was given normal saline instead of cetirizine, and the nonsensitized group had no sensitization or medication. The cytokine gene expressions in the NALT taken from the mice were investigated with real-time quantitative reverse-transcription polymerase chain reaction. The effect of cetirizine on the allergic symptom score, histamine threshold, and the eosinophil count in the nasal septal mucosa were examined also. Compared with the normal mice, the sensitized mice showed significantly increased levels of interleukin (IL)-4 and IL-5 gene expression although the increase of interferon (INF)-gamma gene expression was not significant. In the cetirizine groups, the levels of expression of IL-4, IL-5, and INF-gamma in the NALT were significantly decreased compared with the sensitized group. The cetirizine groups also showed decreased allergic symptom score, histamine threshold, and eosinophil count in the nasal septal mucosa compared with the sensitized group. In conclusion, cetirizine reduced the levels of expression of IL-4, IL-5, and INF-gamma in the NALT of ovalbumin-sensitized mice. Cetirizine also reduced the acute allergic symptom, histamine sensitivity, and eosinophil count in the nasal septal mucosa.

Concurrent inflammation as a determinant of susceptibility to toxicity from xenobiotic agents

Sensitivity to the toxic effects of xenobiotic agents is influenced by a number of factors. Recent evidence derived from studies using experimental animals suggests that inflammation is one of these factors. For example, induction of inflammation by coexposure to bacterial endotoxin, vitamin A or Corynebacterium parvum increases injury in response to a number of xenobiotic agents that target liver. These agents are diverse in chemical nature and in mechanism of hepatotoxic action. Factors critical to the augmentation of liver injury by inflammation include Kupffer cells, neutrophils, cytokines such as tumor necrosis factor-alpha (TNF-alpha) and lipid mediators such as prostaglandins, but these may vary depending on the xenobiotic agent and the mechanisms by which it alters hepatocellular homeostasis. In addition, the timing of inflammagen exposure can qualitatively alter the toxic response to chemicals. Inflammation-induced increases in susceptibility to toxicity are not limited to liver. Concurrent inflammation also sensitizes animals to the toxic effects of agents that damage the respiratory tract, kidney and lymphoid tissue. It is concluded that inflammation should be considered as a determinant of susceptibility to intoxication by xenobiotic exposure.

Prolonged alpha-adrenergic stimulation causes changes in leukocyte distribution and lymphocyte apoptosis in the rat

We have previously shown in the rat model that acutely or chronically increased peripheral catecholamines lead to suppression of lymphocyte responsiveness via alpha(2)-adrenoceptor activation. Here we investigated the effects of alpha-adrenergic treatment on total leukocyte numbers and proportions of leukocyte subsets in peripheral blood and lymphoid tissues. It was found that a 12-h treatment with subcutaneously implanted tablets, one containing norepinephrine (NE) and one propranolol, leads to an increase in total blood leukocyte counts, due to a pronounced increase in granulocytes. In contrast, the numbers of all classes of lymphocytes other than NK cells were decreased. This decrease in blood lymphocytes is apparently not due to redistribution, since in the thymus, spleen, mesenteric and peripheral lymph nodes, the total numbers of lymphocytes were decreased as well, without any changes in subpopulations. Analogous results were obtained with rats adrenalectomized before the catecholamine treatment. Animals that received the alpha-adrenergic treatment displayed significantly more apoptotic cells in the lymphoid organs, as determined by the TUNEL technique. In the spleen, the enhanced rate of apoptosis was confined to the white pulp; red pulp areas exhibited significantly fewer apoptotic cells. Thus, an increased alpha-adrenergic tone in rats led to a general loss of lymphocytes due to lymphocyte directed apoptosis that was independent of glucocorticoids.

[Effect of quinine and quinidine on the status of hematopoietic and lymphoid organs]

The effect of quinine and quinidine introduction in subtoxic doses on the characteristics of the hemopoietic and lymphoid organs was studied in BALB/c mice. The treatment led to reversible anemia and neutrophile leukocytosis in peripheral blood. There was a tendency to the early decrease in neutrophiles the late decrease in lymphocytes in the bone marrow. The quinine-induced decrease in erythrocytes was accompanied by reticulosis, lowered erythrocyte osmoresistance, and intensified spleen erythropoiesis; quinidine induced reticulocytopenia and a decrease in the bone narrow erythroblasts. The use of both compounds was accompanied by a decrease in thymus weight and increase in the thymocyte loss in the early period, followed by the spleen weight increase in the long term.

[Immunity and somatostatin receptors]

The presence of at least three different types of somatostatin receptors in the thymus has been demonstrated using molecular biology techniques or radioimmunological methods. In view of the chemotactical activity shown by somatostatin in other lymphopoietic regions like bone marrow, it was hypothesised that this neuropeptide might play a role in regulating cell migration in the thymus. The selective expression of somatostatin receptors on specific immunocompetent cells, both circulating and in lymphatic organs, allows the neuropeptide to have a modulating action also on the immune system. Functional studies have also shown that somatostatin can influence cell proliferation, cytokine and immunoglobulin production, natural killer cytotoxic activity, the maturation and migration of immune cells in both blood and lymphopoietic tissues. More recent evidence has enabled us to evaluate the altered expression of somatostatin receptors on lymphomonocytes during systemic disease.

MAPK p38 antagonism as a novel method of inhibiting lymphoid immune suppression in polymicrobial sepsis

Although studies indicate that a shift from a Th1 to a Th2 response contributes to a marked suppression of cell-mediated immunity during sepsis, the mechanism by which this occurs remains unknown. Given that the mitogen-activated protein kinase (MAPK) p38 plays a critical role in the activation and function of immune cells, the aim of this study was to determine the contribution of MAPK p38 activation to the immune dysfunction seen in polymicrobial sepsis. To study this, polymicrobial sepsis was induced in C3H/HeN male mice by cecal ligation and puncture (CLP). Splenic lymphocytes and purified T cells were harvested 24 h post-CLP, pretreated with the specific MAPK p38 inhibitor SB-203580, and then stimulated with a monoclonal antibody against the T cell marker CD3. The results indicate that interleukin (IL)-2 release is markedly depressed while the release of the immunosuppressive mediator, IL-10, as well as mRNA levels of IL-10 and IL-4, are augmented after CLP. Inhibition of MAPK p38 suppressed in vitro IL-10 levels as well as IL-10 and IL-4 gene expression while restoring the release of IL-2. To determine whether these in vitro findings could be translated to an in vivo setting, mice were given 100 mg of SB-203580/kg body wt or saline vehicle (intraperitoneal) at 12 h post-CLP. Examination of ex vivo lymphocyte responsiveness indicated that, as with the in vitro finding, septic mouse Th1 responsiveness was restored. In light of our recent finding that delayed in vivo SB-203580 treatment also improved survival after CLP, we believe that these results not only illustrate the role of MAPK p38 in the induction of immunosuppressive agents in sepsis but demonstrate that SB-203580 administration after the initial proinflammatory state of sepsis significantly prevents the morbidity from sepsis.

T cell receptor dynamism of mucosal and systemic CD4+ T cells in the course of an immune response to Escherichia coli heat-labile enterotoxin

The changes in T cell receptor (TCR) Vbeta expression, use, and clonality in mice orally challenged with Escherichia coli heat-labile enterotoxin (LT) were assessed. Use of the TCR Vbeta family and clonality were significantly changed at the single-cell level. In Peyer's patches of treated mice, use of TCR Vbeta6, Vbeta8, and Vbeta14 increased in CD4(+)CD44(+) T cells, compared with use in nontreated mice. On the other hand, use of TCR Vbeta1 and Vbeta8 was enhanced in splenic CD4(+)CD44(+) T cells. Intraepithelial lymphocytes isolated from LT-challenged mice showed expanded clonality (e.g., Vbeta1, Vbeta2, Vbeta9, and Vbeta18) and altered TCR Vbeta use (e.g., Vbeta15, Vbeta16, and Vbeta17). These findings reveal that oral administration of LT has distinct effects on mucosal versus systemic alphabeta T cells for induction of CD4(+) T cells with selected Vbeta use. This most likely reflects the function of LT as a mucosal modulator.

[Effect of human recombinant granulocyte colony-stimulating factor on mouse hematopoietic and lymphoid organs]

Experiments on intact CBA/CALac mice demonstrated that single (1.25 mg/kg) and repeated (0.125 and 1.25 mg/kg, 30 days) injections of recombinant human granulocyte colony stimulation factor lead to reversible dose-dependent granulocyte lineage hyperplasia in bone marrow, regenerative neutrophilic leukocytosis, and thrombocytosis in peripheric blood and to splenic granulo-, erythro-, and thrombocytopoiesis more expressed in males.

[Biological evaluation of the effect of beta-lactam antibiotics on apoptosis in human lymphoid cells in vitro]

Models are developed that allow the effect of beta-lactam antibiotics on the level of apoptosis in human lymphoid cells to be evaluated in vitro. The antibiotics produced a dose-dependent decrease in apoptosis of mature lymphocytes both under normal conditions and in the state of dexamethasone-induced immunodepression. The beta-lactam antibiotics also affect the apoptosis in a pre-B-lymphoblast model. The dexamethasone-induced apoptosis is inhibited by beta-lactam antibiotics only in high doses.

[Effects of bioflavonoids on the toxicity of T-toxin in rats. A morphological study]

Subacute toxicity of T-2 toxin in rats was characterized by a primary defeat of liver, thymus, spleen and intraorgan arteries. In 75% of animals found out increase of the size and adipose infiltration of a liver, in all animals--reduction of the size of thymus (sharp) and spleen (moderate) and pronounced hypoplasia of lymphoid tissue. In the majority of rats vacuolation of cytoplasma of smooth-muscular walls of coronary and intrarenal arteries was revealed. In animals received T-2 toxin against a background of a diet with addition a flour from seeds of milk thistle with high contents of flavonoids, described morphological changes were expressed to a lesser degree and were observed less often. Moderate periportal adipose infiltration of a liver was revealed in 30% of animals, occupancy by cells of lymphoid tissue increased, the quantity and sizes of vacuoles in walls of vessels decreased.

Targeting of 3'-azido 3'-deoxythymidine (AZT)-loaded poly(isohexylcyanoacrylate) nanospheres to the gastrointestinal mucosa and associated lymphoid tissues

PURPOSE

The aim of the studv was to evaluate the capacity of poly(isohexylcyanoacrylate) nanospheres to concentrate 3'-azido 3'-deoxythymidine (AZT) in the intestinal epithelium and associated immunocompetent cells, which are known to be one of the major reservoirs of the human immunodeficiency virus (HIV).

METHODS

The tissue concentration of 3H-radiolabeled AZT in the gastrointestinal (GI) tract was obtained 30 and 9() minutes after intragastric administration to rats at a dose of 0.25 mg AZT/100 g of body weight. The distribution along the intestine was determined. AZT concentrations in the lymph were obtained by lymphatic duct cannulation.

RESULTS

Unlike the solution. nanoparticles did concentrate AZT very cfficiently in the intestinal mucosa, as well as in the Peyer's patches, and could simultaneously control the release of free AZT. Concentration in Peyer's patches was 4 times higher for nanoparticles, compared with the control solution. The tissue concentration was 30-45 microM, which was much higher than the reported IC50 of AZT (0.06-1.36 microM) and was regularly distributed along the gastrointestinal tract.

CONCLUSIONS

Nanoparticles have been shown to be efficient in concentrating AZT in the intestinal epithelium and gut-associated lymphoid tissues, supporting the view that these particles may represent a promising carrier to treat specifically the GI reservoir of HIV.

Therapy for 6.5-7.5 years with recombinant insulin-like growth factor I in children with growth hormone insensitivity syndrome: a clinical research center study

Eight children with GH insensitivity syndrome were treated with recombinant human insulin-like growth factor I (IGF-I) (80--120 microg/kg sc twice daily) for 6.5--7.5 yr. We previously reported that height velocity (HV) improved with treatment (from mean pretreatment HV of 4.0 cm/yr), to 9.3 cm/yr for the first year and 6.2 cm/yr for the second year. HV remained slightly below this during the subsequent years (mean HV: 5.4, 5.5, 5.2, and 4.8 cm/yr during years 3--6). Mean height SD score before therapy was -5.6; and it improved to -4.5, -4.4, and -4.2 after 2, 4, and 6 yr of therapy, respectively. Treatment was accompanied by gain in body weight and fat. Bone age advanced normally in the prepubertal patients, but it advanced more rapidly during the latter years of treatment in those patients undergoing pubertal changes. The growth of spleen and kidneys (determined by ultrasound) was rapid in the first 2--3 yr of therapy. More age- appropriate growth ensued, but six patients had a renal length for height more than 2 SD above the mean at 6--7 yr of treatment. No major adverse changes in biochemical profile were observed. IGF-I-related hypoglycemia occurred early in treatment with the younger patients, but this problem abated as treatment was continued. IGF-I therapy is effective in promoting statural growth in GH insensitivity syndrome patients, but the growth response is neither as intense nor as well-sustained as the growth response to GH among children with GH deficiency.

TPN decreases IL-4 and IL-10 mRNA expression in lipopolysaccharide stimulated intestinal lamina propria cells but glutamine supplementation preserves the expression

Total parenteral nutrition (TPN) decreases intestinal IgA and levels of Th2 cytokines, interleukin (IL)-4, and IL-10 within the supernatants of intestinal homogenates. These cytokines are known to stimulate IgA production in vitro by cells of the gut-associated lymphoid tissue (GALT). Glutamine (GLN) supplementation of TPN normalizes GALT mass and cytokine levels. Because intestinal homogenates contain mucosa which itself is a source of cytokines, it was unclear whether cytokines change within the GALT itself. This study investigates dietary effects on IL-4 and IL-10 cytokine mRNA expression within isolated GALT lamina propria cells after lipopolysaccharide (LPS) stimulation. Prospective randomized experimental trials were used in this study. Fifty-nine mice were randomized to chow, intravenous TPN (IV-TPN), intragastric TPN (IG-TPN), complex enteral diet (CED), or 2% GLN-supplemented TPN (GLN-TPN). In experiment 1, animals were fed chow, IV-TPN, IG-TPN, or CED for 5 days and received intraperitoneal LPS (100 microg/kg BW), and then were sacrificed 1 h later. Intestine was harvested for GALT lamina propria. Total RNA was extracted from lamina propria cells and cytokine mRNA for IL-4, and IL-10 was measured by reverse transcriptase polymerase chain reaction. IgA levels of intestinal washing were also measured with ELISA. In experiment 2, mRNA for IL-4 and IL-10, and intestinal IgA levels were measured in mice fed chow, IV-TPN, or GLN-TPN as in experiment 1. Both IL-4 and IL-10 mRNA expression decreased significantly in IV-TPN mice compared to chow or CED feeding. IG-TPN resulted in IL-10 mRNA expression significantly lower than chow or CED but significantly better than IV-TPN. GLN preserved IL-4 and IL-10 mRNA levels, which correlated with intestinal IgA levels. Route and type of nutrition as well as GLN influence message for the Th2 type IgA-stimulating cytokines, IL-4 and IL-10, within the primary site of GALT IgA production, the lamina propria.

Paper and pulp mill effluent-induced immunotoxicity in freshwater fish Channa punctatus (Bloch)

The influence of temperature variation on the humoral immune response using the plaque-forming cell (PFC) assay in freshwater fish Channa punctatus (Bloch) was investigated. The fish was exposed to 1% concentration (v/v in water) of paper and pulp mill effluent under standard laboratory conditions in glass aquaria. Effect of effluent exposure on the organ weight and organ cellularity was also evaluated. In general, lower temperature in winter produced a subdued response in control as well as experimental group. At higher temperature of summer and rainy seasons, an elevated response was observed. It was revealed that though suppressive effect of effluent was evident during all the seasons, in summer, extent of suppression was greater as compared to winter. Paper and pulp mill effluent exposure resulted in a decrease in the splenic and pronephric (head kidney) cellularity, with more pronounced effect in the summer season. We also studied the effects of the length of exposure on various parameters. Fish were exposed for 15, 30, 60, and 90 days to effluent. Short-term exposure for 15 days induced an elevated PFC response, but change was not statistically significant. Conversely, the exposure for 30, 60, and 90 days significantly reduced (p < 0.05-0.001) the PFC response. Long-term exposure also caused significant reduction (p < 0.05-0.01) in the weights of lymphoid organs (spleen, head kidney, and total kidney). These results show a suppressive effect of chemical constituents of paper and pulp mill effluent on the immune functions. Furthermore, results demonstrated that though modulatory effect of the temperature on immune functions is recognized, it was not a major contributory factor to the elevated immunotoxicity of paper and pulp mill effluent in the seasons of high temperature.

Can we induce tolerance in rheumatoid arthritis?

Oral tolerance (OT) has worked well in numerous laboratory animal models of autoimmune diseases. Humans have been orally tolerized to keyhole limpet hemocyanin (KLH); patients with systemic sclerosis (SSc, scleroderma) have been orally tolerized to oral type I collagen (CI). However, clinical trials of oral type II collagen (CII) therapy in rheumatoid arthritis (RA) have had mixed results. Clinical studies show that compounds (such as nonsteroidal antiinflammatory drugs and prednisone) that inhibit generation of PGE(2) block OT induction. In murine OT models, the PGE(1) analog, misoprostol, reverses the NSAID OT block. These animal studies suggest that OT to CII or other antigens in patients with RA should be inducible if measures are taken to maintain normal prostaglandin function in the gut- associated lymphoid tissue (GALT). A clinical trial is underway in patients with RA to assess whether withholding NSAIDs and prednisone will allow OT to to be induced, and whether oral CII has meaningful clinical efficacy in this disease.

Developmental windows of differential lead-induced immunotoxicity in chickens

The developing immune system of rodents has been shown to exhibit increased sensitivity to lead-induced immunotoxicity compared with that of adults. However, little is known about potential windows of increased vulnerability during discrete periods of embryonic development. To investigate differential embryonic sensitivity to lead-induced immunotoxicity, sublethal doses of lead ranging from 5 to 400 microg/egg were introduced into fertilized Cornell K Strain White Leghorn chicken eggs via the air sac at one of four different stages of embryonic development (5, 7, 9, and 12 days of incubation, designated as E5, E7, E9, and E12, respectively). Lead levels of blood and bone were determined at hatching and lead-induced immunotoxicity was evaluated in 5-6 week old young chickens using a delayed-type hypersensitivity (DTH) reaction against bovine serum albumin (BSA), macrophage production of nitric oxide, and interferon-gamma (IFN-gamma) production by splenic lymphocytes as immune indicators. Splenic lymphocyte production of IFN-gamma was significantly suppressed (measured for E7 and E9 exposures only, P<0.05) among lead treated groups when compared with controls. Macrophage production of nitric oxide (measured as nitrite production) was significantly depressed (P<0.05) following E5, E7, and E9 lead exposures but not following E12 lead exposure. In contrast with this pattern, DTH function was unaltered following the E5, E7, and E9 exposures, but was significantly depressed (P<0.05) after E12 exposure to lead. Since the same lead dose (200 microg/egg) given at E9 and E12 produced the same blood and bone lead levels and resulted in a different outcome regarding DTH function, the capacity of lead to influence DTH function appeared to emerge between days 9 and 12 of in ovo development. Based on these results, it is hypothesized that lead exposure during different windows of embryonic development is likely to result in different immunotoxic outcomes in the juvenile.

Effects of dexamethasone and FK506 on Helicobacter pylori-induced gastritis and bacterial viability in Mongolian gerbils

FK506 and dexamethasone were used to investigate whether or not immunosuppression affects H. pylori colonization and gastric mucosal damage induced by Helicobacter pylori in Mongolian gerbils. Two weeks after H. pylori infection, FK506 and dexamethasone or vehicle alone were subcutaneously administered once daily for the following 2 weeks. FK506 or vehicle alone was administered subcutaneously once daily for 5 weeks (1 week before and 4 weeks after infection). In H. pylori-infected animals for 4 weeks, hemorrhagic erosions and inflammatory responses (neutrophil infiltration and lymphoid follicle formation) were induced in gastric mucosa at an incidence of 100%. Both FK506 and dexamethasone administered for 2 weeks markedly reduced such mucosal changes. In these animals, H. pylori viability in the stomach was significantly elevated. FK506 administered for 5 weeks also significantly inhibited the hemorrhagic erosions, edema and neutrophil infiltration in the stomach. H. pylori viability was slightly elevated as compared with the control. It was concluded that the host immune responses might play dual roles both by deteriorating gastritis induced by H. pylori and by protecting against H. pylori infection in its early stage.

Regulation by chemokines of circulating dendritic cell precursors, and the formation of portal tract-associated lymphoid tissue, in a granulomatous liver disease

We have studied the recruitment and roles of distinct dendritic cell (DC) precursors from the circulation into Propionibacterium acnes-induced granulomas in mouse liver. During infection, F4/80(-)B220(-)CD11c(+) DC precursors appeared in the circulation, migrated into the perisinusoidal space, and matured within newly formed granulomas. Recruited DCs later migrated to the portal area to interact with T cells in what we term "portal tract-associated lymphoid tissue" (PALT). Macrophage inflammatory protein 1alpha attracted blood DC precursors to the sinusoidal granuloma, whereas secondary lymphoid organ chemokine (SLC) attracted mature DCs to the newly identified PALT. Anti-SLC antibody diminished PALT expansion while exacerbating granuloma formation. Therefore, circulating DC precursors can migrate into a solid organ like liver, and participate in the granulomatous reaction in response to specific chemokines.

Impact of TNFalpha, LTalpha, Fc gammaRII and complement receptor on HIV-1 trapping in lymphoid tissue from HIV-infected patients

OBJECTIVES

To investigate HIV trapping mechanisms in patients with acute infection and in asymptomatic individuals prior to and during antiretroviral therapy. To determine the role of complement receptor (CR), Fc gamma receptor II (Fc gammaRII), tumour necrosis factor alpha (TNFalpha), and lymphotoxin alpha (LTalpha) expression in HIV trapping efficiency.

METHODS

Lymphoid tissues from three acutely HIV-infected patients and six asymptomatic, chronically HIV-infected patients collected prior to and during antiretroviral therapy were compared with lymphoid tissues from six HIV-seronegative subjects. HIV, TNFalpha and LTalpha RNA expression was detected and quantified by fluorescence in situ hybridization. CR, Fc gammaRII and HIV p24 antigen were detected and quantified by fluorescence immunohistochemistry.

RESULTS

The amount of trapped HIV did not differ significantly between patients with acute HIV infection and asymptomatic individuals, and was independent of the presence of CR or Fc gammaRII expression. However, in patients with acute infection, the amount of trapped virus was correlated inversely with the number of HIV-infected cells (P = 0.0092) and with the size of the light zone (P = 0.037). In these patients, the number of TNFalpha-expressing cells was correlated inversely with the amount of trapped virus (P = 0.014) and positively correlated with the size of the light zone in germinal centers (P = 0.041). No correlations were observed between TNFalpha or LTalpha expression and Fc gammaRII or CR expression.

CONCLUSION

This report provides the first evidence that in humans TNFalpha is involved in the development of lymphoid follicles, HIV trapping, and, consequently, in early host immune responses. A model is proposed for early events in patients during acute HIV infection.

Effect of amitriptyline on daily variations in cell composition of immune organs in rats with experimental desynchronosis

We studied the effects of amitriptyline (preparation stimulating melatonin synthesis in the pineal gland) on daily variations of cell composition in immune organs of Wistar rats with experimental desynchronosis. Amitriptyline administered in the evening restored the daily dynamics of the number of thymus cells.

Glucocorticoid and Fas ligand induced mucosal lymphocyte apoptosis after burn injury

BACKGROUND

The purpose of this study was to examine the effects of a steam burn injury on apoptosis in gut-associated lymphoid tissue and to determine whether endogenous glucocorticoid and Fas ligand signaling were involved in this process.

METHODS

Histologic analysis, in situ deoxynucleotidyl transferase dUTP nick-end labeling staining and annexin V and 7-amino-actinomycin-D flow cytometry of lymphocyte populations were evaluated in intraepithelial lymphocytes and Peyer's patch. Additional mice were pretreated with a glucocorticoid receptor antagonist (mifepristone) before the steam burn. Similarly, C3H/HeJ-FasL(gld) mice lacking functional Fas ligand were also studied.

RESULTS

Apoptosis was significantly increased in intraepithelial lymphocytes and Peyer's patch after the burn injury. Mifepristone pretreatment significantly reduced apoptosis in both T- and B-cell populations in intraepithelial lymphocytes after the burn injury. In contrast, the increased apoptosis seen in B-cells from Peyer's patch was not seen in C3H/HeJFasL(gld) mice, whereas the increased apoptosis in CD8+ T-cells was unaffected.

CONCLUSION

Both corticosteroids and FasL contribute to the apoptosis in gut-associated lymphoid tissues early after burn injury.

Sterically stabilized liposomes bearing anti-HLA-DR antibodies for targeting the primary cellular reservoirs of HIV-1

The ability of liposomes bearing anti-HLA-DR Fab' fragments at the end termini of polyethyleneglycol chains (sterically stabilized immunoliposomes) to target HLA-DR expressing cells and increase the accumulation of liposomes into lymphoid organs has been evaluated and compared to that of conventional liposomes, sterically stabilized liposomes and conventional immunoliposomes after a single subcutaneous injection to mice. The accumulation of sterically stabilized liposomes in lymph nodes was higher than that of conventional liposomes. Sterically stabilized immunoliposomes accumulated much better than conventional immunoliposomes in all tissues indicating that the presence of PEG has an important effect on the uptake of immunoliposomes by the lymphatic system. Fluorescence microscopy studies showed that sterically stabilized liposomes are mainly localized in macrophage-rich areas such as the subcapsular region of lymph nodes and in the red pulp and marginal zone of the spleen. In contrast, sterically stabilized immunoliposomes mostly accumulated in the cortex in which follicles are located and in the white pulp of the spleen. As the human HLA-DR determinant of the major histocompatibility complex class II is expressed on activated CD4+ T lymphocytes and antigen presenting cells such as monocyte/macrophages and dendritic cells, known as the cellular reservoirs of HIV-1, liposomes bearing anti-HLA-DR antibodies constitute an attractive approach to concentrate drugs in HIV-1 reservoirs and improve their therapeutic effect.

Efficacy of polyvinylpolypyrrolidone in reducing the immunotoxicity of aflatoxin in growing broilers

1. Protective action of an enzyme-linked polyvinylpolypyrrolidone (PVPP, Mycofix Plus) against the immunosuppressive effect of afatoxins (AF) was evaluated by determination of peripheral blood T-lymphocyte proportions and splenic plasma cell counts. Histological changes in lymphoid organs were also investigated by light microscopy. One-d-old broiler chicks (Hybro) received 2.5 mg/kg diet AF (83.06% AFB1, 12.98% AFB2, 2.84% AFG1, 1.12% AFG2) with or without PVPP (3g/kg diet) until 21 d of age. When compared with controls, AF treatment significantly decreased peripheral T-lymphocyte counts. AF caused a slight decrease in splenic plasma cell counts. The addition of PVPP to an AF-containing diet significantly increased T-lymphocyte counts. Splenic plasma cell counts were numerically intermediate between control and AF groups. 3. The dietary addition of PVPP to AF-free diet did not significantly alter either T-lymphocyte or splenic plasma cell counts.

Aromatic retinoid Ro 40-8757 reduces immunotoxicities of cyclophosphamide as revealed by immunohistochemical staining of lymphoid tissues and general pathologic examinations

The aromatic retinoid (arotinoid) Ro 40-8757 (4-[2-[p-(E)-2-(5,6,7,8-Tetrahydro-5,5,8,8-tetramethyl-2-naphthyl) propenyl]phenoxy]ethyl]-morpholine), a compound with antitumor activities, has been studied in a combination therapy with the cytostatic antitumor drug cyclophosphamide (CPA), and was found to protect bone marrow from the toxic effects of CPA. To evaluate its protective effects against CPA toxicities on lymphoid systems, we treated BDF1 mice with Ro 40-8757 orally for 1 to 5 weeks in combination with CPA intraperitoneally. After the combination treatment, mice were subjected to immunohistochemical analysis with antibodies against cell surface markers (Thy 1.2, Lyt-2, L3T4, Kappa chain, and Ia) and, in addition, general pathologic examinations were done. The protective effects of Ro 40-8757 on CPA toxicities were observed. The lymphocyte reductions (both in T cells and B cells) in lymphoid organs by CPA were apparently less severe. In particular, recovery of immature T cells in the thymic cortex was greater in combination treatment with Ro 40-8757 and CPA than in treatment with CPA alone. From these results, it can be concluded that Ro 40-8757 protects the lymphoid organs (thymus, spleen, and lymph node) from the immunotoxicity of CPA, and the protective effect is evident, especially in the thymic cortical lymphocytes.

Treatment of murine lupus with cDNA encoding IFN-gammaR/Fc

IFN-gamma, a pleiotropic cytokine, is a key effector molecule in the pathogenesis of several autoimmune diseases, including lupus. Importantly, deletion of IFN-gamma or IFN-gammaR in several lupus-predisposed mouse strains resulted in significant disease reduction, suggesting the potential for therapeutic intervention. We evaluated whether intramuscular injections of plasmids with cDNA encoding IFN-gammaR/Fc can retard lupus development and progression in MRL-Fas(lpr) mice. Therapy significantly reduced serum levels of IFN-gamma, as well as disease manifestations (autoantibodies, lymphoid hyperplasia, glomerulonephritis, mortality), when treatment was initiated at the predisease stage, particularly when IFN-gammaR/Fc expression was enhanced by electroporation at the injection site. Remarkably, disease was arrested and even ameliorated when this treatment was initiated at an advanced stage. This therapy represents a rare example of disease reversal and makes application of this nonviral gene therapy in humans with lupus (and perhaps other autoimmune/inflammatory conditions) highly promising.

Histopathologic approaches to detect changes indicative of immunotoxicity

Toxicologic pathology is crucial in the identification and characterization of health effects following exposure to xenobiotics, mainly in toxicity experiments in rodents. Regarding regulatory toxicology, histopathology of lymphoid organs and tissues is a cornerstone in the identification of immunotoxic compounds. A 2-tier testing system is usually employed in which the first tier is a general screen for (immuno)toxicity and the second tier consists of specific immune function studies, including host resistance tests or mechanistic studies. The role attributed to histopathology of lymphoid organs in the updated Organisation for Economic Cooperation and Development and Food and Drug Administration guidelines requires improvement and standardization of the histopathology procedures. Optimalization and standardization was started in an international collaborative immunotoxicity study (ICICIS). However, several problems were left unaddressed, mostly because of the few compounds tested in this study. Based on the results of the ICICIS study and the morphologic changes induced by immunotoxic/immunomodulatory compounds observed in other investigations, suggestions are given to further improve the identification and (semi)quantification of histopathologic changes in lymphoid organs and tissues.

Applications of immunohistochemistry in the evaluation of immunosuppressive agents

Immunohistochemistry (IHC) can be a valuable endpoint to evaluate lymphocyte subpopulations in tissues following exposure to presumptive immunosuppressive agents. IHC is more sensitive than conventional histology in detecting subtle differences in lymphocyte numbers and distribution in tissue. In combination with flow cytometric analysis of peripheral lymphocyte subpopulations, IHC can determine if alterations detected in the peripheral blood are a result of trafficking or reflective of changes in tissue distribution. These techniques can be used to evaluate adult animals as well as to evaluate the effects of immunosuppressive agents on fetal tissues in reproductive toxicology studies. While IHC can enhance the detection of subtle changes in lymphocyte subpopulations in tissue, the evaluation of additional endpoints of immune function must be done to further assess the biological or clinical significance of these changes.

Effect of adrenalectomy on ethanol-associated changes in lymphocyte cell numbers and subpopulations in thymus, spleen, and gut-associated lymphoid tissues

Consumption of ethanol (ETOH) by experimental animals and human beings is associated with elevated serum levels of corticosteroids. One of the most robust findings associated with ETOH consumption is a loss of lymphocytes from thymus and spleen, as well as from peripheral lymphoid organs to include mesenteric lymph nodes and Peyer's patches, which are lymphoid organs associated with the gastrointestinal tract. To study the role of corticosteroids in loss of cells from thymus, spleen, and gut-associated lymphoid organs, adrenalectomized (ADX) or intact C57Bl/6 mice were fed a liquid diet containing ETOH (to supply 36% of calories as ETOH) or an isocaloric control diet with a pair-feeding protocol. Loss of lymphocytes from all lymphoid organs was associated closely with serum corticosterone levels in both ETOH-fed and pair-fed groups. ETOH-fed ADX animals showed much less cell loss than did ETOH-fed intact animals. However, there was still an association between ETOH consumption and cell loss when cell loss in ETOH-fed ADX animals was compared with that in ADX pair-fed and ADX chow-fed groups. In both intact and ADX animals ETOH consumption was associated with a loss of immature (CD4(+) and CD8(+)) cells from the thymus. These data lead to the suggestion that corticosteroids are responsible for most of the cell loss from thymus, spleen, mesenteric lymph nodes, and Peyer's patches in association with ETOH consumption. Some cell loss, however, is independent of corticosteroids. The data presented here also support the suggestion that cell loss from lymphoid organs could be the result of nutritional factors.

Supraphysiological level of estrogen exposure in vivo increases lymphoid cell death in mice

Estrogen can enhance or reduce lymphocyte functions in vitro depending on dose and exposure duration. The purpose of this study was to determine the effect of in vivo 17 beta-estradiol (E2) on apoptosis and necrosis in lymphoid tissue of female C567BL/6 mice. Animals were ovariectomized (OVX), ovariectomized and 17 beta-estradiol supplemented (OVX + E2; 71 micrograms E2 per day for 14 days), sham ovariectomized (SHAM), or unhandled controls (CONTROL). Thymus and spleen were removed aseptically, cells dispersed into single cell suspensions in RPMI-1640, and measures of cell damage performed: an annexin V flow cytometric assay for markers of apoptosis and an enzyme-linked immunoassay for measures of DNA fragmentation and necrosis. OVX + E2 mice had 620 +/- 72 pg/ml 17 beta-estradiol in serum in contrast to OVX mice which had 7.6 +/- 5 pg/ml, the SHAM mice which had 2.8 +/- 1 pg/ml of serum E2, and the CONTROL mice which had 3.9 +/- 0.8 pg/ml of serum E2 (p < 0.001). There was a significantly lower percentage of viable thymocytes in OVX + E2 mice compared to the other treatment conditions (p < 0.001, respectively). There was also a significantly higher percentage of annexin V positive thymocytes in OVX + E2 mice (p < 0.005). Measures of DNA fragmentation by ELISA were higher in splenocytes from OVX + E2 mice than in the OVX, SHAM or CONTROL mice (p < 0.005). These results suggest that supraphysiological levels of estrogen in vivo induce damage in lymphoid cells; however, the impact of estrogen associated lymphoid tissue damage on specific immune functions remains to be determined.

Chronic effects of the novel glucocorticosteroid RPR 106541 administered to beagle dogs by inhalation

The preclinical safety of RPR 106541, a novel 17-thiosteroid, was evaluated in young adult and mature dogs by inhalation exposure for 26 weeks and 52 weeks, respectively. A dry powder formulation of RPR 106541 in lactose was administered to young adult dogs (approximately 6 months of age at initiation) at doses of 0 (air and placebo controls), 10, 100, or 1,000 microg/kg/d for 26 weeks. A solution-based aerosol formulation was administered to mature dogs (approximately 10 months at initiation) from a pressurized metered dose inhaler at 0 (air and placebo controls), 10, 50, and 150 microg/kg/d for 52 weeks. Clinical evidence of glucocorticosteroid-induced immunosuppression was observed by weeks 20-26 following relatively high dose exposures (100 microg/kg/d and 1,000 microg/kg/d) in young dogs receiving the dry powder formulation for 26 weeks. Classic glucocorticosteroid effects were observed, including adrenocortical atrophy, reduced bone mass with retention of epiphyseal growth plates in long bones, prominence of stromal adipose tissue in bone marrow, and atrophy of lymphoid tissues. Inhalation administration of RPR 106541 to sexually mature dogs facilitated more definitive characterization of endocrine affects of RPR 106541 as compared with administration in younger, sexually immature animals. Significant effects in female reproductive organs included absence of corpora lutea in association with atresia of vesicular follicles within the ovaries, endometrial hyperplasia, and lobular development of mammary tissue. Discordant development of mammary tissue, accumulation of secretory material within hyperplastic endometrial glands, and hypertrophy of uterine lining epithelium in absence of ovulation were consistent with a secondary progestin effect by a potent glucocorticosteroid.

Model of physiological stress in chickens 2. Dosimetry of adrenocorticotropin

Continuous adrenocorticotropin (ACTH) delivery by mini-osmotic pumps is a reliable method to induce stress in broilers. The present study was conducted to determine the minimum effective dose of ACTH that will evoke physiological stress. Chicks, which had been reared under floor-pen conditions until 5 wk of age received mini-osmotic pumps by surgical implantation. The mini-osmotic pumps delivered 2, 4, 8, or 16 IU of porcine ACTH/kg BW/d for 7 consecutive d. Controls (CON) were untreated chicks. Continuous infusion of ACTH caused dose-related stress responses. Chicks that received 8 or 16 IU showed the greatest responses, whereas those that received 2 or 4 IU were intermediate to the birds dosed with high ACTH and the CON birds. Responses included decreased BW; decreased relative weights of the bursa of Fabricius, thymus, and spleen; and increased relative liver weight. Concomitantly, increased liver lipid and decreased liver moisture were recorded. Plasma concentrations of corticosterone (CS), glucose (GLU), total protein (TP), cholesterol (CHOL), and triglycerides (TRI) and the ratio of heterophils to lymphocytes were increased during ACTH infusion. ACTH infusion at 8 IU/kg BW/d for 7 d was determined to be the minimum effective dose that caused physiological stress in broilers.

Lipopolysaccharide and the trichothecene vomitoxin (deoxynivalenol) synergistically induce apoptosis in murine lymphoid organs

Human exposure to Gram-negative bacterial lipopolysaccharide (LPS) is common and may have an important influence on chemical toxicity. LPS has been shown previously to enhance synergistically the toxicity of trichothecene mycotoxins. Because either of these toxin groups alone characteristically target lymphoid organs at high doses, we evaluated the effects of coexposure to subthreshold doses of Salmonella typhimurium LPS and vomitoxin (VT) administered by intraperitoneal injection and oral gavage of B6C3F1 mice, respectively, on apoptosis in lymphoid tissues after 12-h exposure. The capacity of LPS (0.5 mg/kg body weight) and VT (25 mg/kg body weight) to act synergistically in causing apoptosis in thymus, spleen, and Peyer's patches was suggested by increased internucleosomal DNA fragmentation in whole cell lysates as determined by gel electrophoresis. Following terminal deoxynucleotidyl transferase (TdT)-mediated fluorescein-dUTP nick end-labeling (TUNEL) of tissue sections, a dramatic enhancement of fluorescence intensity indicative of apoptosis was observed in thymus, spleen, Peyer's patches, and bone marrow from coexposed animals as compared to those given the agents alone. Evaluation of hematoxylin and eosin-stained tissue sections of treatment mice revealed the characteristic features of lymphocyte apoptosis, including marked condensation of nuclear chromatin, fragmentation of nuclei, and formation of apoptotic bodies in tissues from mice. Combined treatment with VT (25 mg/kg body weight) and LPS (0.5 mg/kg body weight) significantly increased (p<0.05) the amount of apoptotic thymic and splenic tissue as compared to the expected additive responses of mice receiving either toxin alone. When apoptosis was examined in cell suspensions of thymus, spleen, Peyer's patches, and bone marrow by flow cytometry in conjunction with propidium iodide staining, the percentage of apoptotic cells was significantly increased (p<0.05) in cotreatment groups as compared to the additive responses to LPS and VT given alone. The results provide qualitative and quantitative evidence for the hypothesis that LPS exposure markedly amplifies the toxicity of trichothecenes and that the immune system is a primary target for these interactive effects.

Approaches to the identification and recording of findings in the lymphoreticular organs indicative for immunotoxicity in regulatory type toxicity studies

Recent validation studies showed that histopathological examination of the hematopoietic and lymphoreticular system is one of the most sensitive tools in the evaluation of non-specific immune stimulatory or immune suppressive effects and hazard identification of potential immunotoxicity in routine safety tests. Most immunotoxic effects have a classical dose-response relationship and an immediate effect (i.e. do not need an induction phase). The findings associated with a specific immunomodulatory response are generally not detected morphologically in routine sections of the immune system in safety studies, but may be detected, because of their effects on other organs such as skin (contact dermatitis) or joints and kidneys (immune complex deposits). Careful detailed examination of the immune system may give valuable clues for the possible mechanism of action of the test material, as was also demonstrated in these validation studies.

Orally administered Kampo (Japanese herbal) medicine, "Juzen-Taiho-To" modulates cytokine secretion in gut associated lymphoreticular tissues in mice

The influence of the oral administration of Juzen-Taiho-To (JTT; Si-Quan-Da-Bu-Tang in Chinese), a Kampo (Japanese herbal) medicine, on the cytokine production in mice were investigated. Lymphocytes from spleen (SPN), mesenteric lymph node (MLN) and Peyer's patches (PP) from mice, which received orally administered JTT for 2 weeks, were stimulated with concanavalin A (Con A), and the resulting conditioned medium was tested for cytokine production by ELISA. Administration of JTT caused enhancement of interferon g (IFN-gamma) and interleukin-4 (IL-4) production to some extent but decreased IL-5 production from the SPN. On the other hand, notable changes in cytokine production were observed in lymphocytes from MLN and PP. Administration of JTT increased IFN-gamma production remarkably, as well as IL-5 secretion from both MLN and PP, whereas IL-2 secretion was plainly reduced. The ratio of IFN-gamma and IL-4 was shifted to Th1 dominant in MLN and PP, however changed little in SPN. The flow cytometric analysis revealed that the population of CD3+, CD4+, CD45R/B220+, and CD45RBlowCD4+ cells in each lymphocyte was not changed significantly after oral administration of JTT. These findings demonstrate that the lymphocytes from gut associated lymphoreticular tissues (GALT) are more sensitive to produce cytokines on cytokine production than those from SPN by oral administration of JTT, and that the modulation of cytokine production may be due to functional change of lymphocytes but not change in lymphocytes population.

Oncogenic potential of cyclin E in T-cell lymphomagenesis in transgenic mice: evidence for cooperation between cyclin E and Ras but not Myc

To study the oncogenic activity of cyclin E in an in vivo system we generated transgenic mice expressing high levels of cyclin E in T-lymphocytes by using a construct containing the CD2 locus control region. These animals were neither predisposed to develop any tumors spontaneously nor showed an increased incidence when crossbred with Emu L-myc transgenic mice but developed hyperplasia in peripheral lymphoid organs at later age with an incidence of 27%. When treated with the DNA methylating carcinogen N-methylnitrosourea (MNU) that provokes the development of T-cell lymphomas, CD2-cyclin E transgenic animals came down with T-cell neoplasia showing a significant higher incidence (54%) than normal non transgenic controls (31%). In one of eight tumors that arose in normal MNU treated mice we could find an expected activating point mutation in the Ki-ras gene (12.5%). In contrast, the same mutation occurred in five of 16 tumors from CD2-cyclin E transgenic mice (31.2%). Whereas cyclin E overexpression alone did not lead to an increased CDK2 activity we observed in all tumors that emerged from either MNU treated normal mice or treated CD2-cyclin E transgenics a downregulation of p27KIP1 and a higher histone H1 kinase activity in CDK2 immunoprecipitates compared to normal tissue. These findings demonstrate that high level expression of cyclin E can predispose T-cells for hyperplasia and malignant transformation. However, the results also suggest that this activity of cyclin E is manifest only when other cooperating oncogenes in particular ras genes are present and activated. This would be consistent with our previous finding that cyclin E and Ha-Ras cooperate in focus formation assays in rat embryo fibroblasts.

Polyamine oxidase activity in lymphoid tissues of glucocorticoid-treated rats

Glucocorticoids are known to negatively affect lymphoid tissues, in which they cause programmed cell death. Polyamine depletion, which occurs in glucocorticoid-treated animals by inhibition of biosynthesis and induction of acetylation, may represent a signal to thymocytes for progression into the apoptotic program. Since catalysis of polyamines by the catabolic pathway produces hydrogen peroxide as a by-product, it has been suggested that the apoptotic process may be, in part, due to oxidative stress as a result of hydrogen peroxide production. In order to verify whether polyamine oxidase (EC 1.5.3.11) may play a role in the process, we examined the activity of the enzyme in the thymus and spleen of glucocorticoid-treated rats. We administered dexamethasone (4 mg/kg) or two different doses of corticosterone (4 mg/kg or 30 mg/kg) to rats, which were killed 8 or 24 hr after hormone injection. We found that corticosterone and dexamethasone affected polyamine oxidase activity in both tissues, with an opposite dose-dependent effect of the natural hormone in the thymus. The decrease and increase in polyamine oxidase after the two doses of corticosterone were correlated with the absence and the occurrence of DNA fragmentation, respectively. Moreover, corticosterone affected polyamine oxidase activity earlier (8 hr) than dexamethasone (24 hr), but the synthetic hormone was more efficient than the natural hormone in thymic polyamine depletion. The polyamine oxidase response may represent an important event in lymphoid tissues after glucocorticoid treatment, suggesting a role of the enzyme in the catabolic effects exerted by the two hormones.

The effects of dexamethasone on the response of bronchus-associated lymphoid tissue to intranasal administration of formalin-killed Pasteurella haemolytica A2 in goats

A trial was conducted to observe the immediate and chronic effects in goats of dexamethasone administration on the bronchus-associated lymphoid tissue (BALT) response to intranasal administration of formalin-killed Pasteurella haemolytica A2. Twenty-four goats were divided into four groups. Those in group 1 were injected intramuscularly with 1 mg/kg dexamethasone on three consecutive days, followed by intranasal exposure to formalin-killed P. haemolytica A2 one day after the last dexamethasone treatment. The goats in group 2 were similarly injected with dexamethasone followed by intranasal exposure to formalin-killed P. haemolytica A2 21 days after the last dexamethasone treatment. The animals in group 3 were exposed intranasally to formalin-killed P. haemolytica A2 without prior dexamethasone treatment. The animals in group 4 were untreated controls. The intranasal exposures to formalin-killed P. haemolytica A2 were repeated 2 weeks later. Intranasal exposure to formalin-killed P. haemolytica 1 day after dexamethasone treatment further reduced the number and size of BALT compared to the untreated control. Significantly (p < 0.01) more reduction of BALT occurred in goats exposed to formalin-killed P. haemolytica A2 21 days after dexamethasone treatment. On the other hand, intranasal exposure of goats without prior dexamethasone treatment stimulated the BALT compared to the untreated controls.

Putative role for interleukin-7 in the maintenance of the recirculating naive CD4+ T-cell pool

The capacity of the immune system to respond efficiently to new antigens depends upon a continuous source of naive CD4+ T cells. Such cells exit from the thymus and join the recirculated T-cell pool. Factors present at the sites of naive CD4+ T-cell circulation must be responsible for their survival, since upon removal from their host, naive CD4+ T cells die. However, such factors remain unknown. The presence of the cytokine interleukin-7 (IL-7) in secondary lymphoid organs and the continuous expression of its receptor on naive CD4+ T cells prompted us to examine the possibility that IL-7 might be a survival factor for naive CD4+ T cells. Using naive CD4+ T cells isolated from cord blood we show that IL-7, but not IL-2, can maintain naive CD4+ T-cell viability in vitro for at least 15 days. In addition, we find that IL-7 can induce modest proliferation of naive CD4+ T cells without affecting either their cell surface phenotype or their ability to respond to antigenic stimulation. We also find that after anti-CD3 stimulation, naive CD4+ T cells lose that ability to respond to IL-7. However, if cells are primed with IL-7 prior to antigenic stimulation, their proliferative responses are enhanced. Together, these data suggest a novel and important role for IL-7 in the maintenance and maturation of naive CD4+ T cells, ensuring that they can respond maximally when they first meet antigen in secondary lymphoid tissue.

Short-term exposure to subacute doses of aflatoxin-induced depressed mitogen responses in young mallard ducks

Mallard ducklings were fed diets containing corn naturally contaminated with mixed aflatoxins, purified T-2 toxin, or no detectable mycotoxin in two trials. The aflatoxin level used was 12 ppb in the first trial and 33 ppb in the second. T-2 was added at 2 ppm in both trials. No pathology was associated with the aflatoxin used in this study, and T-2--induced lesions were described in a previous publication. The weights of primary (thymus and bursa of Fabricius) and secondary (spleen) lymphoid organs were significantly reduced in the T-2--treated birds. The total number of viable cells recovered from the thymus was significantly reduced in aflatoxin-treated birds. The numbers of viable cells recovered from thymus, bursa of Fabricius, and spleen were all significantly reduced after treatment with T-2. In each trial, significantly lower mitogenic responses were seen to pokeweed mitogen and concanavalin A in birds fed aflatoxin or T-2, representing reduction in both B-cell and T-cell mitogenesis. Birds fed aflatoxin also had significantly reduced Escherichia coli O55 lipopolysaccharide-induced mitogenic responses. These studies indicate that subacute oral exposure to aflatoxin caused a loss of normal lymphocyte reactivity in mallard ducklings. This finding supports the hypothesis that waterfowl that ingest even small quantities of mycotoxin-contaminated waste grain are likely to be more susceptible to bacterial or viral infections.

Novel neurotrophin-1/B cell-stimulating factor-3: a cytokine of the IL-6 family

We have identified a cytokine of the IL-6 family and named it novel neurotrophin-1/B cell-stimulating factor-3 (NNT-1/BSF-3). NNT-1/BSF-3 cDNA was cloned from activated Jurkat human T cell lymphoma cells. Its sequence predicts a 225-aa protein with a 27-aa signal peptide, a molecular mass of 22 kDa in mature form, and the highest homology to cardiotrophin-1 and ciliary neurotrophic factor. The gene for NNT-1/BSF-3 is on chromosome 11q13. A murine equivalent to NNT-1/BSF-3 also was identified, which shows 96% homology to human NNT-1/BSF-3. NNT-1/BSF-3 mRNA is found mainly in lymph nodes and spleen. NNT-1/BSF-3 induces tyrosine phosphorylation of glycoprotein 130 (gp130), leukemia inhibitory factor receptor beta, and signal transducer and activator of transcription 3 in the SK-N-MC human neuroblastoma cells. NNT-1/BSF-3 shows activities typical of IL-6 family members. In vitro, it supports the survival of chicken embryo motor and sympathetic neurons. In mice, it induces serum amyloid A, potentiates the induction by IL-1 of corticosterone and IL-6, and causes body weight loss and B cell hyperplasia with serum IgG and IgM increase. NNT-1/BSF-3 is a gp130 activator with B-cell stimulating capability.

Elevated mutant frequencies in lymphoid tissues persist throughout plasmacytoma development in BALB/c.lambdaLIZ mice

Using the phage lambdaLIZ-based transgenic in vivo mutagenesis assay, the mean mutant frequencies in the target gene, lacI, were found to be significantly increased in lymphoid tissues of congenic BALB/c.lambdaLIZ N5 mice in the terminal stage of a plasmacytoma induction experiment, 213-280 days after the first i.p. injection of the plasmacytomagenic agent pristane (2,6,10,14-tetramethylpentadecane). In plasmacytoma-bearing mice (n = 7), mutant frequencies in the spleens and mesenteric lymph nodes were elevated 2.46-fold and 5.35-fold, respectively, when compared with age-matched controls. In plasmacytoma-negative mice (n = 11), mutant frequencies were increased 2.30-fold (spleens) and 3.48-fold (mesenteric nodes). These results, interpreted in conjunction with our previous findings (K. Felix et al., Cancer Res., 58: 1616-1619, 1998) of approximately 3-fold elevations in pristane-induced splenic mutagenesis on day 42 postpristane, indicate that increased mutant levels in lymphoid tissues persist throughout plasmacytomagenesis in genetically susceptible BALB/c mice.

The oropharyngeal delivery of interferons: where are we and where do we need to go?

The controversial concept of oral delivery of interferon (IFN) is reviewed in relation to possible mechanisms of action. Although there is a rational basis and some positive clinical results for believing that it may work, problems remain to understand which is the most effective IFN preparation and why. Owing to a minimal cost and lack of toxicity, the oral as well as other unconventional routes of IFN delivery deserve to be evaluated because they may become useful.