Printer Friendly

Attenuated Allergic Responses to House Dust Mite Antigen in Feed-Restricted Rats.

Caloric restriction has been shown to alter a broad range of immunological end points in both experimental animals and humans. The objective of this study was to investigate the effect of short-term moderate feed restriction (25% reduction) on allergic immune responses in Brown Norway rats. After 3 weeks of acclimation to their feed regimens, rats were sensitized and 2 weeks later challenged with house dust mite (HDM) antigen via intratracheal instillation. Feed restriction resulted in lower levels of antigen-specific IgE in serum and reduced antigenspecific lympho-proliferative activity in pulmonary lymph nodes. Feed restriction also attenuated pulmonary inflammation, as evidenced by lower levels of lactate dehydrogenase and total protein, decreased infiltration of neutrophils and eosinophils, and reduced secretion of pro-inflammatory cytokine tumor necrosis factor (TNF)-[Alpha] in bronchoalveolar lavage fluid. In addition, feed restriction decreased TNF-[Alpha] secretion in serum and decreased mRNA expression of TNF-[Alpha] and interleukin-6 in pulmonary lymph nodes. We conclude that feed restriction strongly dampened the allergic immune responses to HDM in rats and that this attenuation was associated with decreased expression and secretion of pro-inflammatory cytokines. Key words: allergy, asthma, dust mites, eosinophil, feed restriction; IgE, immune response, inflammation, lung, T lymphocyte, tumor necrosis factor-[Alpha]. Environ Health Perspect 108:1125-1131 (2000). [Online 1 November 2000] http://ehpnet1.niehs.nih.gov/docs/2000/108p1125-1131dong/abstract.html

Feed restriction studies in rodents show significant delays in aging-related degenerative diseases (1) and protection against cancer (2). It is also clear that feed restriction alters innate and specific immune function; however, its effects on allergic immune responses and resultant inflammation are not known.

The incidence of asthma has increased dramatically in the United States and other industrialized nations over the last 20 years. Changes in lifestyle may account for some of this increase. A recent epidemiologic study reported an association between being overweight (body mass index higher than 85th percentile) and the severity of asthma symptoms in susceptible children (3). An animal study showed that 18-hr fasting reduced ovalbumin-induced bronchoconstriction in guinea pigs (4). Other than these few reports, there is little information on feed restriction and allergic responses in the literature.

Inflammation is a hallmark of allergic asthma, and there is mounting evidence that feed restriction is anti-inflammatory. For example, long-term caloric restriction inhibits age-related increases in the serum pro-inflammatory cytokines tumor necrosis factor (TNF)-[Alpha] and interleukin (IL)-6 in mice (5). We have recently demonstrated that short-term dietary restriction mitigates ozone-induced pulmonary inflammation in rats, and this is associated with lower levels of the pro-inflammatory cytokine IL-6 in bronchial alveolar lavage (BAL) fluid (6). We also showed that feed restriction improves antibacterial immune defenses in the lung (7) and that these effects were attributed to the increased phagocytic activity of alveolar macrophages. In another animal study, feed-restricted rats did not differ in T-cell mitogen responses compared to ad libitum controls but had decreased lympho-proliferative responses to recall antigens, suggesting that aspects of acquired (antigen-specific) immune function were impaired (8).

It is suggested that an imbalance of T-helper 1 (Th1) and Th2 cytokines plays an important role in allergic responses in animals (9) and in humans (10). Elevated levels of IL-4, IL-5, and IL-10 secretion by Th2 CD4+ cells, as well as suppressed levels of IL-2, and interferon (IFN-[Gamma]) secretion by Th1 CD4+ cells may enhance production of IgE, promote mast cell proliferation and maturation, augment airway hyperresponsiveness, and increase recruitment of eosinophils. Effects of feed restriction on the Th1 and Th2 responses have not been studied.

Our laboratory has developed a rat model of allergic responses to house dust mite (HDM) antigen and evaluated the impact of various chemical exposures on allergic responses to HDM (11-13). This model exhibits many of the hallmarks of allergic asthma such as increased HDM-specific IgE, elevated HDM-specific lympho-proliferative responses in lung-associated lymph nodes, antigen-induced bronchospasm, airway hyperresponsiveness, and pulmonary eosinophilia (14). We used this model to evaluate whether feed restriction can attenuate allergic responses to HDM antigen and whether this is accompanied by changes in pro-inflammatory cytokines levels in the pulmonary system.

Materials and Methods

Animals and dietary regimen. Ten-week-old female Brown Norway rats were purchased from Harlan Sprague-Dawley (Indianapolis, IN), housed two per cage in an environmentally controlled room with a 12-hr light/dark cycle, and fed Laboratory Rodent Diet 5001 (Purina Mills, St. Louis, MO). Randomly selected animals were tested serologically upon arrival and monitored throughout the study to ensure that rats were free of Sendai virus, murine pneumonia virus, a variety of other rodent viruses, as well as Mycoplasma sp. Rats were also monitored for and found to be free of ectoparasites and endoparasites. All procedures were approved by the Animal Care and Use Committee of the National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, before commencing the study.

After a 1-week acclimation period, the dietary treatments were initiated as follows. Average feed consumption by animals fed ad libitum was determined daily. This value was then multiplied by 0.75, and the resultant mass of food was presented to the restricted animals the next morning. The restricted animals always ate the entire portion presented. The dietary treatment began 3 weeks before antigen exposure and continued throughout the experiment. We monitored body weights every other day throughout the study. All nutrients provided by the dietary regimens exceeded levels recommended by the National Research Council (15).

Antigen sensitization and challenge procedure. Semipurified extracts of Dermatophagoides farinae and D. pteronyssinuss (Greer Laboratories, Lenoir, NC) were rehydrated in sterile saline to 10 mg/mL (containing 172 mg HDM group I antigen/mg dry weight), mixed, and stored in aliquots at -70 [degrees] C. After 3 weeks of acclimation of their respective dietary regimens, the rats were lightly anesthetized by halothane (Aldrich, Milwaukee, WI) inhalation and sensitized with a single intratracheal instillation of 17.6 [micro]g of HDM group I antigen in 0.3 mL of sterile saline. Two weeks later, rats were challenged by the identical procedure.

Experimental design. Rats were acclimated for 1 week before dietary treatment and randomly divided into two groups, ad libitum-fed (control) and feed restricted, with 20 rats for each group. At each of the following four time points, 5 animals per group were euthanized by sodium pentobarbital overdose (180 mg/kg, intraperitoneal injection): 7 days postsensitization, 14 days postsensitization, 2 days postchallenge, and 7 days postchallenge. We obtained samples at each time point. Serum was collected through cardiac puncture, and bronchoalveolar lavage (BAL) fluid was collected after lavage with a single volume of saline (35 mL/kg) via tracheal cannula. The spleen and pulmonary lymph nodes were also collected. We analyzed serum samples for HDM-specific IgE, IgG, and IgA. In addition, differential cell counts were performed on BAL cells and BAL fluid was analyzed for lactate dehydrogenase (LDH), total protein, eosinophil peroxidase (EPO), IL-2, IL-4, IL-6, IL-10, IFN-[Gamma], and TNF-[Alpha]. The lymphoproliferative responses of cells from spleen and pulmonary lymph nodes were assessed. We also determined cytokine gene expression in cells from pulmonary lymph nodes. Data reported are representative of three separate experiments.

Biochemical and cytological analyses. Cell counts in BAL fluid were obtained with a hemocytometer, and cell viability was assessed by trypan blue dye exclusion. After dilution, 50,000 cells from each sample were centrifuged onto microscope slides using a Cytospin Model II (Shandon, Pittsburgh, PA) and stained with Diff Quick (American Scientific, Sewickley, PA). We performed differential counts in duplicate on 200 cells per specimen for identification of alveolar macrophages, polymorphonuclear leukocytes (PMN), lymphocytes, and eosinophils.

After centrifugation at 425g for 10 min at 4 [degrees] C, we assessed supernatant BAL fluid for LDH using a commercially available method (Sigma, St. Louis, MO). Total protein in BAL fluid was detected with Pierce Coomassie Plus protein assay reagent (Pierce, Rockford, IL) using bovine serum albumin (BSA; Sigma) as a standard. EPO, as a measure of eosinophil activation, was determined using the OPD Tablet Set (Sigma). All biochemical assays were modified for automated analysis by a Cobas Fara II centrifugal spectrophotometer (Hoffman-LaRoche, Branchburg, NJ).

Antibody analysis. We assessed serum and BAL fluid for HDM-specific immunoglobulins by ELISA. Before the assay, pooled serum and BAL samples were tested to determine appropriate dilution factors for the linear range of the reaction curve. For the assay, 96-well polystyrene plates (Costar, Cambridge, MA) were coated overnight with 17.6 [micro]g semipurified HDM/mL of 0.05 M carbonate buffer (pH 9.6) at 4 [degress] C. The plates were washed five times with 0.1 M phosphate-buffered saline (PBS) containing 0.05% Tween 20. Each well was filled with a blocking solution of 1% BSA in PBS and incubated for 2 hr before washing. Diluted serum samples (1:100 for IgG, 1:10 for IgE and IgA) or BAL fluid (1:10 IgG, 1:2 for IgE and IgA) were added to the wells and incubated overnight with the coated HDM at 4 [degrees] C. Following another wash step, biotin-labeled mouse anti-rat IgG, IgE, or IgA (Accurate, Westbury, NY) was added to the plates at optimal dilutions and incubated for 2 hr at room temperature. We removed excess antibody by washing, and added horse radish peroxidase-streptavidin (Vector Laboratories, Burlingame, CA) to the plates, which were then incubated for another 2 hr at room temperature. A solution of TM blue enzyme reagent (TSI-CDP, Milford, MA) was added and the color change was measured at a wavelength of 650 nm with an ELISA plate reader (Molecular Devices, Menlo Park, CA). We subtracted background values from all sample values to correct for nonspecific binding effects. The ELISA assay was optimized using a checkerboard titration to provide optimal concentrations of antigen and antibodies for the reaction. We compared reaction times and optical density (OD) values to historical data obtained during the development of this assay. Other experiments from our laboratory (14) have shown good concordance between the IgE ELISA assay and antigen-specific passive cutaneous anaphylaxis (PCA) tests.

Lymphoproliferative responses. Spleens and lung-associated lymph nodes from the mainstem bronchus were collected and gently homogenized in RPMI medium supplemented with 10% fetal calf serum, 2 mM L-glutamine, 20 mM Hepes buffer, 5 x [10.sup.-5] M 2-mercaptoethanol, 100 units/mL penicillin, and 100 mg/mL streptomycin (GIBCO, Grand Island, NY). After three lysing steps with 0.89% [NH.sub.4]Cl and RPMI medium, cells were washed, counted with a hemocytometer, and resuspended to a concentration of 5 x [10.sup.6] cells/mL. We assessed cell viability by trypan blue dye exclusion. We added 100 [micro]L aliquots of each cell suspension in triplicate to wells of 96-well, flat-bottomed tissue culture plates. Cells were incubated in the presence of 1.76 [micro]g semipurified HDM or medium alone for 4 days. Preliminary studies indicated that these were optimal culture conditions. Eighteen hours before the end of the incubation period, 0.5 [micro]g [[sup.3]H]thymidine (DuPont, Wilminton, DE) in 20 [micro]L RPMI medium was added to each well. Cells were harvested automatically onto filters (Skatron, Sterling, VA) and the [[sup.3]H]thymidine incorporation was measured by scintillation (Packard, Meriden, CT). Lymphocyte responsiveness was expressed as the difference in radiotracer counts between cells incubated with HDM (stimulated) and those incubated with medium alone (unstimulated).

Cytokine assays. We determined TNF-[Alpha], IL-1[Beta], IL-6, IFN-[Gamma], IL-2, IL-4, and IL-10 secretions in serum and in BAL fluid according to the manufacturer's procedure using commercial ELISA kits from BioSource (Camarillo, CA).

Semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR). We isolated cells from lung-associated lymph nodes during lymphocyte proliferation assay and pooled them according to treatment. About 5 x [10.sup.6] cells from each treatment group were homogenized in 1 mL Tri Reagent (Sigma), and total cellular RNA was extracted according to the manufacturer's procedure. To synthesize complementary DNA, 1.0 [micro]g of RNA was resuspended in a 20-[micro]L final volume of the reaction buffer (50 [micro]m Tris-HCL, 75 mM KCl, 10 mM dithiothreitol, 3.0 mM Mg[Cl.sub.2], 10 mM of each deoxynucleotide triphosphate, 1 U/[micro]L of RNase inhibitor, pH 8.3; Perkin-Elmer Cetus, Foster City, CA) containing 0.5 [micro]g oligo d(T) 12-18 primer (GIBCO BRL, Gaithersburg, MD). When the reaction mixture reached 42 [micro] C, 200 U SuperScript II reverse transcriptase (GIBCO BRL) was added into each tube, incubated for 30 min at 42 [degrees] C, and stopped by denaturing the enzyme at 99 [degrees] C for 5 min. The reaction mixture was diluted with distilled water to 50 [micro]L. PCR primers for rat glyceraldehyde-3-phosphate dehydrogenase (G3PDH), IL-1, IL-6, TNF-[Alpha], IL-2, and IFN-[Gamma] were purchased commercially from Clontech (Palo Alto, CA); PCR primers for rat IL-4 and IL-5 were synthesized by the core facility of the Human Studies Division at the U.S. EPA (Chapel Hill, NC). The sequences of the primers for rat IL-4 and IL-5 were as follows: a) IL-4 (sense: 5'-TGATGGGTCTCAGCCCCCACCTTGC-3', anti-sense: 5'CTTTCAGTGTTGTGAGCGTGGACTC-3'); and b) IL-5 (sense: 5'-TGACGAGCAATGAGACGATGT-3', anti-sense: 5'-TCATCACGCCAAGGAACTCT-3').

We added 5-[micro]L aliquots of the synthesized cDNA to 45 [micro]L of the PCR mixture containing 1.5 [micro]l of Mg[Cl.sub.2] (0.2 mM), 5 [micro]l of 10 x PCR buffer (20 mM Tris HCl, 50 mM KCl, pH 8.4), 1 [micro]L deoxynucleotides (0.2 mM each), 1 [micro]L of sense and anti-sense primers (0.5 [micro]L each, 0.2 mM), 0.3 [micro]L Taq DNA polymerase (Promega, Madison, WI), and 36.2 [micro]L of RNase-free water. The amplification was initiated by 1 min of denaturation at 95 [degrees] C for 1 cycle, followed by 20-35 cycles at 94 [degrees] C for 15 sec, 55 [degrees] C for 30 sec, and 72 [degrees] C for 30 sec using a GeneAmp PCR System 9600 DNA Thermal Cycler (Perkin-Elmer Cetus). After the last cycle of amplification, the samples were incubated at 72 [degrees] C for 7 min. For each set of primers, dilutions of cDNA were amplified for 20, 25, 30, and 35 cycles to define optimal conditions for linearity and to permit semiquantitative analysis of signal strength.

Amplified PCR products along with the molecular weight marker, 100 bp DNA ladder (GIBCO BRL), were separated electrophoretically (2% agarose gel at 75 V for 60 min) and visualized by ultraviolet illumination after staining with 0.5 [micro]g/mL ethidium bromide. Gels were photographed with Type 55 positive/negative film (Polaroid, Cambridge, MA). We determined the relative changes in mRNA transcripts and performed the densitometric analysis of the captured image using the AlphaImage 2000 Documentation and Analysis System (Alpha Innotech, San Leandro, CA). The area under the curve was normalized against G3PDH content.

Statistical analysis. We analyzed the data for all outcome variables, except body weights, using a two-way analysis of variance (ANOVA) model. The two independent effects were food consumption at two levels, ad libitum and restricted, and time after sensitization or challenge at four levels, 7 days postssensitization, 14 days postsensitization, 2 days postchallenge, and 7 days postchallenge. After identification of significant main effects or interactions, we performed pair-wise comparisons among combinations of the various independent variables.

We analyzed the time course of body weight using multivariate ANOVA. The single independent variable was food consumption at two levels, ad libitum and restricted, and the dependent variable was animal weight. We performed comparisons to the initial weight to assess whether a subsequent weight difference, attributable to feeding regimens, had appeared.

The level of significance was set at 0.05. We made appropriate multiple comparison adjustments to preserve the experiment-wise error rate.

Results

Two physiologically distinctive groups of rats were created by imposing a moderate feed restriction (25% of the amount consumed by ad libitum group) on one group of rats. Ad libitum-fed rats grew steadily at about 0.8 g a day, as indicated by their body weight (Figure 1). After a weight loss of 15.8 g in the first 4 days, the feed-restricted rats also grew steadily during the rest of the experimental period at about the same rate as ad libitum group. However, the weight gap caused by feed restriction persisted in feed-restricted animals.

[GRAPH OMITTED]

To assess the effect of feed restriction on allergic immune responses to HDM, allergen-specific IgE was measured in the serum (Figure 2). Equivalent levels of HDM-specific IgE were found in ad libitum and feed-restricted groups after sensitization. After antigen challenge, however, the HDM-specific IgE increased in the ad libitum group but decreased by 50% in the feed-restricted group compared to levels before antigen challenge. No differences in the level of serum HDM-specific IgG or IgA were found between the two groups at any time points measured.

[GRAPHS OMITTED]

Both ad libitum-fed and feed-restricted rats were instilled with 0.3 mL of HDM antigen. Because feed-restricted rats were lighter in body weight, they might have received more antigen per milligram of lung tissue than ad libitum-fed rats, assuming lung size correlates positively with body weight. This possibility does not adversely affect the interpretation of the experimental results, because feed-restricted rats exhibited less allergic responses to HDM antigen despite the fact that they might have received more antigen per milligram of lung than ad libitum-fed rats.

Levels of LDH, total protein, and EPO in BAL fluid were measured to evaluate pulmonary cell membrane integrity, edema, and eosinophil activition, respectively. The dynamics of these biochemical analyses revealed that the overall levels of LDH, total protein, and EPO appeared lower in the feed-restricted group compared to the ad libitum group. There were increases in LDH, total protein, and EPO levels 2 days after HDM challenge in ad libitum rats compared to levels before antigen challenge (Figure 3); however, such responses were sharply attenuated in feed-restricted rats.

[GRAPHS OMITTED]

Pulmonary allergic inflammation in response to HDM was examined by differential cell count of BAL fluid. The number of eosinophils, neutrophils, macrophages, and lymphocytes in ad libitum rats increased dramatically 2 days after HDM challenge (Figure 4). In contrast, feed-restricted rats showed no such cellular influx, although there was a significant increase in the number of BAL macrophages in these animals 14 days after HDM sensitization.

[GRAPHS OMITTED]

Equivalent levels of lymphocyte proliferation were found in ad libitum and feed-restricted groups after antigen sensitization. After antigen challenge, however, lymphoproliferative responses increased after HDM challenge in ad libitum rats (Figure 5) but were only modestly higher in the feed-restricted animals. Lymphocyte proliferation of spleen cells in response to HDM was similar between the two groups at all time points measured.

[GRAPHS OMITTED]

The secretion of the pro-inflammatory cytokine TNF-[Alpha] in serum and BAL fluid differed between two dietary groups. Compared to levels before antigen challenge, levels of TNF-[Alpha] were significantly increased 2 days after HDM challenge in both serum and BAL fluid of the ad libitum group, and the magnitude of the increase was higher in BAL than in serum (Figure 6). Such an increase was not found in serum and was significantly reduced in BAL fluid from feed-restricted rats. The secretion of IL-1[Beta] and IL-6 was undetectable in both serum and BAL fluid in all animals (data not shown).

[GRAPHS OMITTED]

The mRNA levels of pro-inflammatory cytokines TNF-[Alpha] and IL-6 in preparations from pooled pulmonary lymph nodes appeared to be lower in the feed-restricted group compared to the ad libitum group 7 days after HDM sensitization (Figure 7). After challenge, however, mRNA levels increased and were equivalent between control and feed-restricted rats. Unlike IL-6 and TNF-[Alpha] expression, no differential responses in IL-1 expression were apparent between the ad libitum and feed-restricted groups.

[ILLUSTRATION OMITTED]

To investigate the effect of feed restriction on the balance of Th1 and Th2 cytokines, the protein levels of IL-2, IFN[Gamma], IL-4, and IL-10 in serum and in BAL fluid as well as the mRNA levels of IL-2, IFN[Gamma], IL-4, and IL-5 in pulmonary lymph nodes were assessed. No detectable levels of IL-2, IFN[Gamma], IL-4, or IL-10 were found in serum or in BAL fluid, and there were no differences between ad libitum and feed-restricted groups in mRNA of cytokines detected (data not shown).

Discussion

Several studies have shown that feed restriction can alter immune responses to experimental antigens (8,16) and may have profound effects on antioxidant balance in various tissues (17). The purpose of this study was to determine if feed restriction affected immunologic sensitization to HDM antigen in Brown Norway rats and if the dietary restriction could alter the outcome of allergic disease induced after a subsequent antigen challenge. We found that feed restriction did not affect initial antigen priming: no changes in lymphocyte proliferative responses and antigen-specific antibody production were evident. However, after antigen challenge, the boosting of immune function and the inflammatory influx seen in the lungs of ad libitum-fed animals was significantly abrogated in feed-restricted rats. Specifically, these animals had decreased levels of HDM-specific IgE in serum, lower HDM-specific lymphocyte proliferation in pulmonary lymph nodes, reduced infiltration of eosinophils into the lung, and lower levels of LDH and protein in the BAL fluid.

It is unlikely that a general reduction in lymphocyte reactivity accounted for these observations because several studies have shown that moderate feed restriction (of the magnitude used on our studies) actually enhances T- and B-cell mitogen responses, natural killer cell function, and macrophage function in mice and rats (7,8). Rather, it appears that acquired (antigen-specific) immune responses were reduced and that these effects were associated with decreased immune-mediated lung disease.

Although the mechanisms for this attenuation are unclear, reduced initial expression of the pro-inflammatory cytokines TNF-[Alpha] and IL-6 was associated with decreased allergic responses to HDM in feed-restricted animals. TNF-[Alpha] is an important mediator in human allergic reactions (18). Numerous studies have demonstrated that TNF-[Alpha] upregulates intrapulmonary expression of ICAM-1 (intercellular adhesion molecule-1) (19), enhances adhesion of activated eosinophils to respiratory epithelial cells (20), and mediates recruitment of both neutrophils and eosinophils during airway inflammation (21). Studies also show that TNF-[Alpha] is necessary for eosinophil transendothelial migration (22). In one particular study using Brown Norway rats, a dose-dependent inhibition of neutrophil and eosinophil infiltration into BAL fluid was observed when TNF-[Alpha] receptors were blocked by Ro 45-2081 (23).

After antigen challenge, TNF-[Alpha] levels were consistently lower in both the serum and BAL fluid of feed-restricted animals. mRNA expression of this cytokine and IL-6, however, was increased after challenge and was equivalent between dietary groups. Quite possibly, the RT-PCR reactions from tissue extracted at these time points were saturated compared to baseline levels. Alternatively, cytokine expression may have been less affected in the lymph nodes compared to lung tissue, where differences in antioxidant levels and mRNA expression of TNF-[Alpha] are known to exist between ad libitum and feed-restricted animals (6,7).

Two possible mechanisms for the decreased immune responses and allergic lung disease in feed-restricted rats are overproduction of corticosteroids and reduced oxidative stress. Dietary restriction is associated with diurnal hypercorticism in rodents (24), which in turn reduces pro-inflammatory cytokine production (25-28) and inhibits expression of adhesion molecules (29). Furthermore, glucocorticoids suppress IL-5 and granulocytic macrophage--colony-stimulating factor production and eosinophilia in nasal and pulmonary tissues (30,31). Dietary restriction also resets the oxidant status in tissues and organs via a combination of decreased free-radical production and increased levels of antioxidants (17). Because overproduction of oxidants by leukocytes plays an important role in inflammatory lung .disease and asthma, it is reasonable to expect that reduced free-radical production would lead to decreased tissue damage during an inflammatory event.

Although we propose hypercorticism and reduced oxidative stress to be two separate plausible mechanisms by which feed restriction might attenuate immune and inflammatory responses, their cellular and molecular interactions are, in fact, closely related. Glucocorticoids reduce glucose uptake and energy metabolism in peripheral tissues, which subsequently decreases the rate of intracellular glycoxidation, thus mitigating oxidative stress through reduced production of mitochondrial free-radicals. Increased glucocorticoids and decreased free-radical output reduce the expression of nuclear transcription factors AP-1 (activation protein-1) and NF[Kappa]B (nuclear factor kappa B) (32), which regulate the expression of pro-inflammatory cytokines, chemokines, and adhesion molecules. The combination of altered transcriptional activity of immunoregulatory cytokines and differences in oxidant status between ad libitum-fed and feed-restricted rats provides a rational explanation for differences in the severity of inflammatory lung disease between these two different treatment groups. Although the mechanisms for this effect are still largely unknown and warrant more exploration, our results indicate that nutritional status should be considered as an important feature when modeling human disease in experimental systems and that unrestricted caloric intake may be a risk factor in immune-mediated lung diseases such as asthma.

REFERENCES AND NOTES

(1.) Yu BP. How diet influences the aging process of the rat. Proc Soc Exp Biol Med 205:97-105 (1994).

(2.) Hursting S, Kari FW. The anti-carcinogenic effects of dietary restriction: mechanisms and future directions. Mutat Res 443:233-249 (1999).

(3.) Luder E, Melnik TA, DiMais M. Association of being overweight with greater asthma symptoms in inner city black and Hispanic children. J Pediatr 132:699-703 (1998).

(4.) Underwood DC, Mattews JK, Osborn RR, Hay DW. Food restriction-mediated adrenal influences on antigen-induced bronchoconstriction and airway eosinophil influx in the guinea pig. Int Arch Allergy Immunol 117:52-59 (1998).

(5.) Spaulding CC, Walford RL, Effros RB. Calorie restriction inhibits the age-related dysregulation of the cytokines TNF-[Alpha] and IL-6 in C3B10RF1 mice. Mech Ageing Dev 93:87-94 (1997).

(6.) Kari FW, Hatch G, Slade R, Crissman K, Simeonova PP, Luster MI. Dietary restriction mitigates ozone-induced lung inflammation in rats: a role for endogenous antioxidants. Am J Respir Cell Mol Biol 17:740-747 (1997).

(7.) Dong W, Selgrade MJK, Gilmour MI, Lange RW, Park P, Luster MI, Kari FW. Altered alveolar macrophage function in calorie-restricted rats. Am J Respir Cell Mol Biol 19:462-469 (1998).

(8.) Fernandes G, Venkatraman JT, Turturro A, Attwood VG, Hart RW. Effect of food restriction on life span and immune functions in long-lived Fischer-344 x Brown Norway F1 rats. J Clin Immunol 17(1):85-95 (1997).

(9.) Padrid PA, Mathur M, Li X, Herrmann K, Qin Y, Cattamanchi Weinstock AJ, Elliott D, Sperling AL, Bluestone JA. CTLA41g inhibits airway eosinophila and hyperresponsiveness by regulating the development of Th1/Th2 subsets in a murine model of asthma. Am J Respir Cell Mol Biol 18:453-462 (1998).

(10). Hakonarson H, Maskeri N, Carter C, Grunstein MM. Regulation of TH1- and TH2-type cytokine expression and action in atopic asthmatic sensitized airway smooth muscle. J Clin Invest 103:1077-1087 (1999).

(11.) Gilmour MI, Park P, Selgrade MK. Increased immune and inflammatory responses to dust mite antigen in rats exposed to 5 ppm N[O.sub.2]. Fundam Appl Toxicol 31:65-70 (1996).

(12). Dong W, Gilmour MI, Lambert AL, Selgrade MJK. Enhanced allergic responses to house dust mite by oral exposure to carbaryl in rats. Toxicol Sci 44:63-69 (1998).

(13). Lambert AL, Dong W, Winsett DW, Selgrade MJK, Gilmour MI. Residual oil fly ash exposure enhances allergic sensitization to house dust mite. Toxicol Appl Pharmacol 158:269-277 (1999).

(14.) Lambert AL, Winsett DW, Costa DL Selgrade MJK, Gilmour MI. Transfer of allergic airway responses with serum and lymphocytes from rats sensitized to dust mite. Am J Respir Crit Care Mad 157:1991-1999 (1998).

(15.) National Research Council. Nutrient requirements for the laboratory rat: In: Nutrient Requirements of Laboratory Animals (Subcommittee on Laboratory Animal Nutrition, Committee on Animal Nutrition, Board on Agriculture, National Research Council, eds). Washington, DC:National Academy Press, 1995;11-79.

(16.) Christadoss P, Talal N, Lindstrom J, Fernandes G. Suppression of cellular and humeral immunity to T-dependent antigens by calorie restriction. Cell Immunol 88:1-8 (1984).

(17.) Sohal RS, Weindruch R. Oxidative stress, caloric restriction, and aging. Science 273:59-63 (1996).

(18.) Casale TB, Costa, Galli SJ. TNF-[Alpha] is important in human lung allergic reactions. Am J Respir Cell Mol Biol 15:35-44 (1998).

(19.) Mulligan MS, Vaporciyan AA, Miyasaka M, Tamatani T, Ward PA. Tumor necrosis factor-[Alpha] regulates in vivo intrapulmonary expression of ICAM-1. Am J Pathol 142:1739-1749 (1993).

(20.) Godding V, Stark JM, Sedgwick JB, Busse WW. Adhesion of activated eosinophils to respiratory epithelial cells is enhanced by tumor necrosis factor-[Alpha] and interleukin-1[Beta]. Am J Respir Cell Mol Biol 13:555-562 (1995).

(21). Lukaca NW, Strieter RM, Chensue SW, Widmer M, Kunkel SL. TNF-[Alpha] mediates recruitment of neutrophils and eosinophils during airway inflammation. J Immunol 154:5411-5417 (1995).

(22.) Erger RA, Casale TB. Tumor necrosis factor-[Alpha] is necessary for granulocyte-macrophage-colony-stimulating-factor-induced eosinophil transendothelial migration. Int Arch Allergy Immunol 115:24-32 (1998).

(23). Renzetti LM, Paciorek PM, Tannu SA, Rinaldi N, Tocker, JE, Wasserman MA, Gater PR. Pharmacological evidence for tumor necrosis factor as a mediator of allergic inflammation in the airways. J Pharmacol Exp Ther 278:847-853 (1996).

(24.) Klebanov S, Diais S, Stavinoha WB, Suh Y, Nelson JF. Hyperadrenocorticism, attenuated inflammation, and the life-prolonging action of food restriction in mice. J Gerontol Biol Sci 50A:B78-B82 (1995).

(25.) Miyamasu M, Misaki Y, Izuni S, Takaishi T, Morita Y, Nakamura H, Matsushima K, Kasahara T, Hirai K. Glucocorticoids inhibit chemokine generation by human eosinophils. J Allergy Clin Immunol 101:75-83 (1998).

(26.) Bessler H, Mendel C, Straussberg R, Gurary N, Aloni D, Sirota L. Effects of dexamethasone on IL-1[Beta], IL-6, and TNF-[Alpha] production by mononuclear cells of newborns and adults. Biol Neonate 75:225-233 (1999).

(27). Inoue H, Aizawa H, Fukuyama S, Takata S, Matsumoto K, Shigyo M, Koto H, Hara N. Effect of inhaled glucocorticoids on the cellular profile and cytokine levels in induced sputum from asthmatic patients. Lung 177:53-62 (1999).

(28.) Lanz M J, Leung DY, White CW. Comparison of exhaled nitric oxide to spirometry during emergency treatment of asthma exacerbations with glucocorticoids in children. Ann Allergy Asthma Immunol 82:161-164 (1999).

(29.) Atsuta J, Plitt J, Bochner BS, Schleimer RP. Inhibition of VCAM-1 expression in human bronchial epithelial cells by glucocorticoids. Am J Respir Cell Mol Biol 20:643-650 (1999).

(30.) Danahay H, Broadley K J, McCabe P J, Nials AT, Sanjar S. The potential roles of cytokines, IL-5 and IL-8, and plasma cortisol in the anti-inflammatory actions of phosphodiesterase inhibitors in sensitized guinea-pig airways. Pulm Pharmacol Ther 10:277-285 (1997).

(31.) Nouri-Aria KT, Masuyama K, Jacobson MR, Rak S, Lowhagen O, Schotman E, Hamid QA, Durham SR. Granulocyte/macrophage-colony stimulating factor in allergen-induced rhinitis: cellular localization, relation to tissue eosinophilia and influence of topical corticosteroid. Int Arch Allergy Immunol 117:248-254 (1998).

(32.) Pinkus R, Weiner LM, Daniel V. Role of oxidants and antioxidants in the induction of AP-1, NF[Kappa]B, and glutathione S-transferase gene expression. J Biol Chem 271:13422-13429 (1996).

Address correspondence to: F.W. Kari, National Institute of Environmental Health Sciences, MD Fl-05, P.O. Box 12233, 111 T.W. Alexander Drive, Research Triangle Park, NC 27709 USA. Telephone: (919) 541-2926. Fax: (919) 541-1460. E-mail: kari@niehs.nih.gov

We thank S. Gavett, G. Hatch, and D. Morgan for their helpful comments. We thank J. Richards for technical support and D. Doerfler for statistical assistance. This work was performed while W. Dong held a National Research Council--U.S. EPA Research Associateship.

The research described in this article has been reviewed by the National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, and approved for publication. Approval does not signify that the contents necessarily reflect the views and policies of the agency, nor the mention of trade names or commercial products constitute endorsement or recommendation for use.

Received 10 April 2000; accepted 24 July 2000.

Wumin Dong,(1) Frank W. Kari,(2) Mary Jane K. Selgrade,(1) and M. Ian Gilmour(1)

(1) Immunotoxicology Branch, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA; (2) Laboratory of Environmental Carcinogenesis and Mutagenesis, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
COPYRIGHT 2000 National Institute of Environmental Health Sciences
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2000, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

Article Details
Printer friendly Cite/link Email Feedback
Author:Gilmour, M. Ian
Publication:Environmental Health Perspectives
Date:Dec 1, 2000
Words:5315
Previous Article:Effects on the Immune System Associated with Living Near a Pesticide Dump Site.
Next Article:Embryotoxicity of the Alkylphenol Degradation Product 4-Nonylphenol to the Crustacean Daphnia magna.
Topics:


Related Articles
Study shows reducing dust, other allergens could cut kids' asthma.
Identifying Allergens: Which Present a Risk?
Effects of physical interventions on house dust mite allergen levels in carpet, bed, and upholstery dust in low-income, urban homes. (Articles).
POLLUTION ALERT! HELP KEEP ALLERGIES AT BAY WITH A CLEAN INDOOR ENVIRONMENT.
Indoor exposure to molds and allergic sensitization. (Research Articles).
Mite and pet allergen levels in homes of children born to allergic and nonallergic parents: the PIAMA study. (Children's Health: Articles).
Child-care sites, health threats. (Environment).
Assessment of the allergic potential of food protein extracts and proteins on oral application using the Brown Norway rat model. (mini-monograph).
Metal composition of ambient P[M.sub.2.5] influences severity of allergic airways disease in mice.
How exposures to biologics influence the induction and incidence of asthma.

Terms of use | Copyright © 2017 Farlex, Inc. | Feedback | For webmasters