Dosimetry of a set-up for the exposure of newborn mice to 2.45-GHZ WiFi frequencies

This work describes the dosimetry of a two waveguide cell system designed to expose newborn mice to electromagnetic fields associated with wireless fidelity signals in the frequency band of 2.45 GHz. The dosimetric characterisation of the exposure system was performed both numerically and experimentally. Specific measures were adopted with regard to the increase in both weight and size of the biological target during the exposure period. The specific absorption rate (SAR, W kg(-1)) for 1 W of input power vs. weight curve was assessed. The curve evidenced an SAR pattern varying from <1 W kg(-1) to >6 W kg(-1) during the first 5 weeks of the life of mice, with a peak resonance phenomenon at a weight around 5 g. This curve was used to set the appropriate level of input power during experimental sessions to expose the growing mice to a defined and constant dose.

Increased levels of NF-kappaB inhibitors (IkappaBalpha and IkappaBgamma) in the intestinal mucosa of Crohn's disease patients during infliximab treatment

The treatment with infliximab is employed successfully in Crohn's disease (CD) but predictors of efficacy are lacking. Activation of the transcription factor NF-kB has been demonstrated in CD and its inhibition is one of the mechanisms by which anti-inflammatory agents exert their effects. We evaluated the production of TNFalpha by peripheral blood mononuclear cells (PBMC) and the levels of NF-kappaB family molecules in the intestinal mucosa during infliximab therapy in 12 patients. TNFalpha was assayed on supernatants of PBMC culture stimulated with PHA or LPS. Immunohistochemistry was also done on intestinal biopsies. In six patients, Western blot analysis of the NF-kappaB subunit Rel-A, and its inhibitors IkappaBalpha and IkappaBgamma was performed on intestinal biopsies and PBMC. The TNFalpha production by LPS stimulated PBMC showed mild changes, while it was increased by PHA-stimulated PBMC after treatment. The number of inflammatory cells in the intestinal mucosa was reduced (p<0.002) by the treatment. In five out of six cases we detected an increase of the IkappaBalpha and IkappaBgamma)inhibitor levels in intestinal biopsies after treatment. An increase of IkappaB inhibitors levels could be one of the mechanisms by which infliximab decreases NF-kappaB activity and exerts its anti-inflammatory effects.

Activity of a nitroxylated analog of daunorubicin, ruboxyl, in B-lymphoproliferative disorders

A nitroxylated analog of daunorubicin, ruboxyl (RBX), showed low toxicity but significant lympholytic effect in preclinical evaluations. A series of studies in vitro and in animals demonstrate that RBX is a putative agent in the treatment of many neoplasms. We report the results of a study in mice in which RBX showed selective B-lymphocyte immunosuppression. On the basis of this experience, RBX was administered to 3 patients with multiple myeloma and two patients with Waldenström's disease. The results of this pilot clinical study show that this compound has good activity and low myelotoxicity and cardiotoxicity, but seems to be characterized by a threatening immunosuppressive effect.

Inhibition of IgG1 and IgE production by stimulation of the B cell CTLA-4 receptor

Although a large amount of information is available on the activity of CTLA-4 in T cells, the role of this receptor in B cells has not been previously characterized. Our results show that CD40 or LPS stimulation in the presence of IL-4 induces CTLA-4 expression in purified B cells; the maximum level is reached in both membrane and intracellular compartments after 48-72 h. Engagement of the B cell CTLA-4 by immobilized mAb inhibits IgG1 and IgE production and reduces the frequency of IgG1- and IgE-expressing B cells. Cepsilon and Cgamma(1) germline mRNA expression as well as NF-kappaB and STAT6 activation, events required for isotype switching, are also inhibited by CTLA-4 engagement. Together these findings show the critical role of CTLA-4 in the control of IL-4-driven isotype switching and suggest new approaches for modulating immediate-type hypersensitivity responses.

Hematopoietic reconstitution after lethal irradiation and bone marrow transplantation: effects of different hematopoietic cytokines on the recovery of thymus, spleen and blood cells

Lethally irradiated mice were grafted with syngeneic bone marrow cells or left ungrafted. Mice of each group were injected with different hematopoietic cytokines for 5 consecutive days starting immediately after irradiation or left uninjected. The recovery of lymphoid tissues induced by hematopoietic cytokines 7 days after irradiation and bone marrow cell transplantation was comparable to that observed at days 21-28 in irradiated, bone marrow-grafted, but cytokine-uninjected mice. IL-11 or IL-6, in combination with IL-3, was able to hasten thymus, spleen and blood cell numbers and functions. SCF also displayed a detectable effect when used with IL-3. Conversely, the IL-6 superagonist K-7/D-6 was able, when injected alone, to induce significant recovery of thymus, spleen and blood cells. Thus, K-7/D-6 appears to be a most efficient cytokine for fast reconstitution of lymphoid tissues after irradiation and bone marrow transplantation.

Skin tumorigenesis by initiators and promoters of different chemical structures in lines of mice selectively bred for resistance (Car-r) or susceptibility (Car-s) to two-stage skin carcinogenesis

Carcinogenesis-resistant (Car-R) and carcinogenesis-susceptible (Car-S) mice were obtained applying a bi-directional selective breeding approach to a two-stage skin carcinogenesis protocol, using 9,10-dimethyl-1,2-benzanthracene (DMBA) as initiator and 12-O-tetradecanoylphorbol-13-acetate (TPA) as promoter. Sixteen generations of selection produced a remarkable interline difference in responsiveness to two-stage skin carcinogenesis between Car-R and Car-S: identical DMBA (25 microgram) and TPA (5 microgram) doses induced papillomas in 100% of Car-S compared with 3.3% of Car-R mice and maximal responses of 14.3 or 0.03 papillomas/mouse, respectively, despite the shorter promotion applied to Car-S (49 vs. 208 days). To define the factors determining this great difference, Car-R and Car-S mice were challenged by initiators/promoters chemically unrelated to those used for selection. Both lines were subjected to either initiation by N-methyl-N-nitrosourea (MNU) followed by TPA promotion, or promotion by benzoyl peroxide, or 1,8-dihydroxy-3-methyl-9-anthrone (chrysarobin) following DMBA initiation. Initiation with MNU induced a 10-fold tumour incidence in Car-S compared with Car-R mice, and a 32-fold difference in tumour induction rate. The 2 lines also differed markedly in susceptibility to benzoyl peroxide promotion: Car-S mice initiated with 25 microgram DMBA and promoted with 7.5 mg benzoyl peroxide showed a 12-fold tumour incidence and a 103-fold tumour induction rate compared with the corresponding Car-R group. Both lines, however, were refractory to chrysarobin promotion. The progression of papillomas to carcinomas was examined in all Car-S groups. The incidence of mice that developed carcinomas was 57% in MNU-initiated mice. Benzoyl peroxide was also able to promote carcinoma development in Car-S mice, though with a lower incidence (30.4%) than TPA.

Cytotoxic T lymphocyte antigen 4 (CTLA-4) inhibits CD28-induced IkappaBalpha degradation and RelA activation

Purified CD4+ cells from the spleens of C57BL/6 mice were stimulated with anti-CD3, anti-CD28 and anti-cytotoxic T lymphocyte antigen (CTLA)-4 monoclonal antibodies. The results show that CTLA-4 stimulation inhibits IL-2 production induced by CD3-CD28 co-stimulation. Since CD3-CD28 co-stimulation induces IkappaBalpha degradation and consequently activates RelA, an NFkappaB family member relevant for the induction of IL-2 mRNA transcription, we tested whether the inhibitory effect of CTLA-4 stimulation interferes with this mechanism. CD3-CD28 co-stimulation was found to induce a drastic decrease in cytoplasmic IkappaBalpha and increase in nuclear RelA. CTLA-4 stimulation abrogates this effect of co-stimulation by increasing the level of cytoplasmic IkappaBalpha and decreasing the nuclear RelA level and DNA-binding activity. In conclusion, our results indicate that the inhibitory effect of CTLA-4 engagement on cytokine production correlates with prevention of IkappaBalpha degradation and inhibition of RelA nuclear translocation.

Inhibition of IL-2 production by Nil-2-a in murine T cells

The loss of IL-2 production is the main defect accounting for age-related immunodeficiencies. We have investigated the molecular mechanisms involved in the decrease of IL-2 production in CD4+ T cells from aging mice. Our results demonstrate that the stability of IL-2 mRNA increases in T cells from young mice, whereas it declines in T cells from old mice with the time of stimulation, suggesting the existence of different mechanisms of post-transcriptional regulation in young and old mice. We found that the IL-2 mRNA level in T cells from young but not from old mice increased up to 6- to 10-fold by addition of cycloheximide (CHX) while the stability of IL-2 mRNA is not affected. We then looked for IL-2 inducible inhibitory factors in T cells from young and old mice and demonstrated the presence of Nil-2-a, a zinc finger protein which negatively controls IL-2 gene transcription in human cells. This protein could be detected in T cells from both young and old mice, yet, in the presence of CHX, its binding activity was reduced by 75% in T cells from young but not from old mice. These findings show that Nil-2-a accounts for the negative control of IL-2 production in the mouse and explain the reduced IL-2 production in aging.

Role of mRNA stability in the different patterns of cytokine production by CD4+ cells from young and old mice

CD4+ cells from young (3 months) and old (19 months) mice were stimulated by plate-bound anti-CD3 monoclonal antibody (mAb) alone or also by soluble anti-CD28 mAb. Supernatants were analysed by enzyme-linked immunosorbent assay (ELISA) to determine cytokine concentrations. Total RNA was extracted from cells, reverse transcribed and the cDNA amplified by polymerase chain reaction (PCR) to evaluate the amount of specific mRNA. The results indicate that anti-CD3 alone is not sufficient to induce interleukin-2 (IL-2) production in CD4+ cells from both young and old mice. However, anti-CD28, together with anti-CD3 mAb, induces a much higher production of IL-2 in CD4+ cells from young as compared with old mice. Conversely, interferon-gamma (IFN-gamma) production is also induced by anti-CD3 alone and is higher in CD4+ cells from old as compared with young mice. Upon addition of anti-CD28 mAb, IFN-gamma production increases in both groups, but it remains much higher in old than in young mice. Also the production of IL-4 and IL-10 is induced by anti-CD3 mAb but it is increased by the addition of anti-CD28 mAb. CD4+ cells from old mice produce more IL-4 and IL-10 as compared with cells from young mice. The amounts of cytokine specific mRNA in CD4+ cells from young and old mice parallel the cytokine levels in culture supernatants. Results on the mRNA turnover indicate that when CD4+ cells are stimulated by anti-CD3 or costimulated also by anti-CD28 mAb, the IFN-gamma, IL-4 and IL-10 specific mRNAs are more stable in old than in young mice, suggesting that mRNA stability has a relevant role in the different patterns of cytokine production.

Use of hematopoietic cytokines to accelerate the recovery of the immune system in irradiated mice

In our previous studies aimed at designing appropriate strategies to accelerate recovery of the immune system after irradiation, we found that the hematopoietic cytokine recombinant murine (rmu) interleukin (IL)-3 was able to induce differentiation and growth of thymocytes and splenic T and B lymphocytes in mice exposed to x-rays (200-500 cGy). The recovery, however, was complete at 7 days only after a dose of 200 cGy, whereas 2, 3, and 4 weeks were necessary to achieve full recovery after 300, 400, and 500 cGy, respectively. These studies were extended to investigate the effects of another hematopoietic cytokine, recombinant human (rhu) IL-11, a bone marrow stromal-derived cytokine, administered together with IL-3 to irradiated mice. The synergistic effect of the two cytokines was evident when relatively small doses of rhu IL-11 were injected with an optimal dose of rmu IL-3.

Regulation of cytokine production in aging: use of recombinant cytokines to upregulate mitogen-stimulated spleen cells

We investigated the production of IL-2 and IFN-gamma (Th1 type) and IL-4 (Th2 type) cytokines by mitogen-activated spleen cells from young, adult and old mice. Cytokine production was evaluated in culture supernatants by CTLL proliferation (IL-2), ELISA (IFN-gamma), CT4.S proliferation (IL-4) and in mRNA extracted from activated CD4+ cells by RT-PCR (IL-2, IFN-gamma and IL-4). Results show that the production of IL-2, as protein and mRNA, is profoundly depressed by aging, whereas that of IFN-gamma, as protein and mRNA, firstly declines and then increases with age. The production of IL-4, as protein, monotonically declines with aging whereas, as mRNA, firstly decreases and then increases above the level in young mice. Spleen cells in culture were also incubated with mitogens and with a recombinant cytokine (IL-1 beta, IL-2, IL-3, IL-4, IL-12 or IFN-gamma) at various concentrations. It was found that recombinant cytokines by and large enhance cytokine production when the level induced by mitogens only is low. This conclusion applies to IL-2 and IFN-gamma production as protein and mRNA. The addition of recombinant cytokines also increases the production of IL-4 at the protein level in spleen cells from old mice but, at the mRNA level, only in spleen cells from young mice. This finding suggests age-related changes in IL-4-specific mRNA transcription rate and post-transcriptional half-life as well as translation kinetics.

Genetics of chemical carcinogenesis--III. Tissue-specificity of the genes controlling susceptibility and resistance to skin carcinogenesis in the mouse

Carcinogenesis-resistant (Car-R) and carcinogenesis-susceptible (Car-S) mice have been obtained by the method of bi-directional selective breeding. After 10 generations of selection Car-R and Car-S mice show a remarkable difference in their response to chemical carcinogenesis. Car-R and Car-S mice, initiated and promoted by skin application of 9,10-dimethyl-1,2-benzanthracene (DMBA) and 12-O-tetradecanoylphorbol-13-acetate (TPA) reach a tumour multiplicity of 0.05 and 6.2, respectively, after 49 days of promotion. When benzo[a]pyrene (B[a]P) is topically applied for initiation, followed by TPA promotion, Car-R and Car-S mice maintain a large difference in sensitivity to skin tumour induction. Car-S mice are also more susceptible than Car-R mice to complete carcinogenesis produced by single or repeated applications of DMBA only. On the contrary, when DMBA or B[a]P are administered by subcutaneous injection rather than by topical application, no significant difference in tumour incidence is observed between the two lines. All tumours induced by topical administration of carcinogens on the skin are of epithelial origin, whereas the tumours produced by subcutaneous injection are of connectival origin. These observations suggest a tissue-specific effect of the selected genes, probably restricted at the skin level.

IL-11 synergizes with IL-3 in promoting the recovery of the immune system after irradiation

In our previous studies aiming at the design of appropriate strategies to accelerate the recovery of the immune system after irradiation, we found that recombinant murine (rmu) IL-3 treatment induces differentiation and growth of thymocytes and splenic T and B lymphocytes in mice exposed to X-rays (200-500 cGy). These studies were extended to investigate the effects of recombinant human (rhu) IL-11. Results indicate that rhuIL-11 is able to restore thymus and spleen cell numbers as well as T and B cell mitotic responsiveness in mice exposed to 200 cGy but not to 300 cGy. However, recovery of thymus and spleen cell numbers and functions could be accelerated also in mice exposed to higher dose if rhuIL-11 was given with rmuIL-3. Recovery was complete as soon as 7 days after irradiation. A large dose of both cytokines was explored and the synergistic effect of the two cytokines was evident when a relatively small dose of rhuIL-11 was injected with graded doses of rmuIL-3. The recovery of the immune system in irradiated mice injected with these cytokines was independent from Bcl-2 expression, suggesting that elimination of damaged cells by apoptosis is unaffected by hematopoietic cytokines.

Hormone replacement therapy affects various immune cell subsets and natural cytotoxicity

The effects of hormone replacement therapy (HRT) on lymphocytes and granulocytes have never been determined in detail. Ten healthy menopausal women (age 49-51 years; menopause less than 2 years) were treated for 6 months by administering transdermal estradiol (100 micrograms/day for 21 consecutive days) and oral medroxyprogesterone acetate (10 mg/day from day 10 to day 21). Days 22-28 were therapy-free. All subjects were examined during the first and the last month of treatment: evaluations were carried out on days 0, 8, 21 and 28. CD4+CD45RO+ cells were found to be significantly reduced on day 8. CD56+ cells and CD8+CD11b+ cells were decreased on day 21 and recovered basal level on day 28. Natural killer cell function was transiently increased on day 8 and greatly reduced on day 21. During the first month of therapy, the expression of Leu8 and CD11b antigens on granulocyte membranes was significantly affected by HRT. Taken together, the results indicate that HRT selectively affects various immune cell subsets.

Genetics of chemical carcinogenesis--II. Papilloma induction and malignant conversion in susceptible (Car-s) and resistant (Car-R) lines of mice produced by bidirectional selective breeding and in their (Car-S X Car-R) F1 hybrids

Susceptible (Car-S) and resistant (Car-R) lines of mice separated by 10 consecutive generations of bidirectional selective breeding present a very large difference in responsiveness to two-stage skin carcinogenesis. Car-S mice initiated with 0.5 micrograms 9,10-dimethyl-1,2-benzanthracene (DMBA) and promoted with 0.25 micrograms 12-O-tetradecanoyl-phorbol-13-acetate (TPA) for 77 days showed a papilloma incidence of 88% and a tumour multiplicity of 3.2 +/- 0.4 (mean +/- SE), with a tumour induction rate of 0.415. Car-R mice initiated with larger DMBA and TPA doses (50 micrograms and 20 micrograms respectively) and promoted for 111 days gave a comparable papilloma response: incidence 65%, tumour multiplicity 3.2 +/- 0.6 and tumour induction rate 0.288. The difference in papilloma response between the two lines is due to the interaction of genetic and environmental factors. In order to overcome the genetic effect with environmental factors and induce in Car-R a papilloma response comparable to that of Car-S, the DMBA dose had to be increased up to 100 times, that of TPA 40 times and the promotion time augmented by 44%. Papilloma to carcinoma conversion 112 days after the end of promotion depends on the DMBA and TPA doses applied. The number of carcinomas induced in Car-S mice and in (Car-S X Car-R) F1 hybrids was larger than that induced in Car-R mice, but the ratio of carcinoma conversion was lower, therefore a larger proportion of the small number of papillomas induced in the Car-R mice progressed to malignancy. The dominance effect measured in (Car-S X Car-R) F1 hybrids demonstrated that the susceptibility to papilloma induction was an incomplete dominant character (d/a = 0.38), whereas for carcinoma conversion the resistance was incompletely dominant (d/a = -0.49).

Comparison of 7,12-dimethylbenz(a)anthracene-DNA adduction in the epidermis of two lines of mice selected for resistance (CAR-R) or susceptibility (CAR-S) to skin carcinogenesis

Two lines of mice were produced by bidirectional selective breeding: one resistant (CAR-R) and one susceptible (CAR-S) to two-stage skin carcinogenesis by dimethylbenz(a)anthracene and 12-O-tetradecanoyl-phorbol-13-acetate. The dimethylbenz(a)anthracene-DNA adduct formation was compared in the two lines by a postlabeling procedure so as to determine whether the striking interline difference observed as to tumor incidence could (in part) be due to differences in the formation of DNA-reactive metabolites. Results show that qualitatively, adduct profiles in CAR-R and CAR-S epidermis are similar. Quantitatively, the total binding level is slightly higher in CAR-S versus CAR-R mice during the 30-day follow-up. However, these minor differences do not increase in function of the response to selection observed through three consecutive generations. A 2- or 4-week promotion with 12-O-tetradecanoylphorbol-13-acetate enhances the decrease of adduct level in the two lines. This effect is somewhat more pronounced in CAR-S mice. Results strongly suggest that the expression of the genes responsible for CAR-R/CAR-S phenotypic difference affects mainly the postinitiation stages.

Melatonin increases antigen presentation and amplifies specific and non specific signals for T-cell proliferation

Our preceding results have shown that melatonin administration to normal and immunodepressed mice increases significantly the antibody response. We also found that melatonin is able to restore the impaired T-helper cell activity in immunodepressed mice. The present study shows that melatonin enhances antigen presentation by splenic macrophages to T-cells. This effect is concomitant with an increase in the expression of MHC class II molecules and production of IL-1 and TNF-alpha. Considering the role of antigen presentation and cytokine production in the initiation of the immune response, the present findings provide evidence for relevant mechanisms that may account for the regulatory role of the pineal gland in immunoregulation.

[Immunogenetic factors in the onset of experimental tumors]

The influence of immunological and genetic factors on the appearance of experimental tumors has been studied in mice by means of bidirectional selection. We found that the incidence of lymphomas, solid tumors and chronic nephritis is greater in mice selected for low antibody response than in mice selected for high antibody response. These findings suggest that the genes that control the antibody response also regulate life-span and resistance to neoplastic and inflammatory diseases. Similarly, we are carrying out bidirectional selective breeding to obtain two lines of mice, one sensitive and one resistant to the induction of cutaneous papillomas by chemical carcinogens. The two lines differ notably in terms of both percent of incidence and tumor multiplicity. The results of this study demonstrate clearly that resistance and susceptibility to carcinogenesis are subject to polygenic control.