Eotaxin represents the principal eosinophil chemoattractant in a novel murine asthma model induced by house dust containing cockroach allergens

Asthma represents a serious health problem particularly for inner city children, and recent studies have identified that cockroach allergens trigger many of these asthmatic attacks. This study tested the concept that asthma-like pulmonary inflammation may be induced by house dust containing cockroach allergens. An aqueous extract was prepared from a house dust sample containing endotoxin and high levels of cockroach allergens. BALB/c mice were immunized with the house dust extract (HDE) and received two additional pulmonary challenges. Bronchoalveolar lavage (BAL) eosinophil counts and eotaxin levels were significantly increased in immunized mice exposed to the HDE, whereas neutrophils were the predominant BAL inflammatory cell in the unimmunized mice. Kinetics studies in immunized mice demonstrated a peak pulmonary inflammatory response 48 h after the last challenge. The allergic response in this model was further confirmed by histological and physiological studies demonstrating a significant influx of eosinophils and lymphocytes in the peribronchial area, and severe airway hyperreactivity through whole-body plethysmography. The specificity of the response was established by immunizing with HDE and challenging with purified cockroach allergen, which induced pulmonary eosinophilia and airway hyperreactivity. Ab inhibition of eotaxin significantly inhibited the number of BAL eosinophils. These data describe a novel murine model of asthma-like pulmonary inflammation induced by house dust containing endotoxin and cockroach allergens and further demonstrate that eotaxin represents the principal chemoattractant for the recruitment of the pulmonary eosinophils.     

Static and dynamic mechanics of the murine lung after intratracheal bleomycin

Background

Endotoxins are ubiquitously present in the environment and constitute a significant component of ambient air. These substances have been shown to modulate the allergic response, however a consensus has yet to be reached whether they attenuate or exacerbate asthmatic responses. The current investigation examined whether reducing the concentration of lipopolysaccharide (LPS) in a house dust extract (HDE) containing high concentrations of both cockroach allergens [1] and LPS would attenuate asthma-like pulmonary inflammation.

Methods

Mice were sensitized with CRA and challenged with the intact HDE, containing 182 ng of LPS, or an LPS-reduced HDE containing 3 ng LPS, but an equivalent amount of CRA. Multiple parameters of asthma-like pulmonary inflammation were measured.

Results

Compared to HDE challenged mice, the LPS-reduced HDE challenged mice had significantly reduced TNFα levels in the bronchoalveolar lavage fluid. Plasma levels of IgE and IgG1 were significantly reduced, however no change in CRA-specific IgE was detected. In HDE mice, plasma IgG2a levels were similar to naïve mice, while LPS-reduced HDE mice had significantly greater concentrations. Reduced levels of LPS in the HDE did not decrease eosinophil or neutrophil recruitment into the alveolar space. Equivalent inflammatory cell recruitment occurred despite having generally higher pulmonary concentrations of eotaxins and CXC chemokines in the LPS-reduced HDE group. LPS-reduced HDE challenge induced significantly higher concentrations of IFNγ, and IL-5 and IL-13 in the BAL fluid, but did not decrease airways hyperresponsiveness or airway resistance to methacholine challenge. Conclusion: These data show that reduction of LPS levels in the HDE does not significantly protect against the severity of asthma-like pulmonary inflammation.     

Characterization of temperature-sensitive strains of Neospora caninum in mice

Temperature-sensitive (ts) strains of the Neospora caninum tachyzoites were selected by chemical mutagenesis and selection for growth at 32 C. Three ts strains and the parental, N. caninum wild-type strain, NC-1, were examined in the present study for their ability to cause disease in inbred BALB/c mice, outbred ICR mice, and chemically immunosuppressed ICR mice. In BALB/c mice, all 3 strains failed to induce clinical disease, whereas infection with the NC-1 strain caused central nervous system disease and death in some mice. No disease was observed in ICR mice inoculated with the 3 ts strains or the NC-1 strain. All immunosuppressed ICR mice inoculated with the NC-1 strain died, whereas no immunosuppressed mice inoculated with the NCts-4 strain and only 1 of 5 mice inoculated with the NCts-8 and NCts-12 strains died. The NCts-4 and NCts-12 strains reverted to a wild-type phenotype when grown at 37 C. Vaccination of BALB/c mice with live, but not frozen NCts-8 strain tachyzoites induced significant (P < 0.05) protection following NC-1 strain challenge.     

Heligmosomoides polygyrus (=Nematospiroides dubius): the development of self-cure and/or protection in several strains of mice.

Strains of outbred (ICR/CD1 and S--W) and inbred (BALB/C and C57BL/6) mice vaccinated subcutaneously (SQ) with 500, 1,000, or 2,000 exsheathed Heligmosomoides polygyrus larvae developed varying levels of protection upon subsequent oral challenge with larvae. In contrast, the inbred C3H/HEJ strain failed to develop protection at any dosage level tested. ICR/CD1 mice vaccinated intraperitoneally with exsheathed larvae developed a high level of resistance but exhibited extensive adhesions of the viscera. When ensheathed larvae were used for vaccination, ICR/CD1 mice developed a moderate level of protection; but 1% of the vaccine dose was recovered in the intestine as adult stages. Both the inbred and outbred strains given multiple oral infections developed a protection response similar to that strain's response following parenteral vaccination. The specificity of this protection was demonstrated using various complex foreign antigens. In contrast, the self-cure response was observed only in the S--W strain.     

Mycoplasma pneumoniae CARDS Toxin Exacerbates Ovalbumin-Induced Asthma-Like Inflammation in BALB/c Mice

Mycoplasma pneumoniae causes a range of airway and extrapulmonary pathologies in humans. Clinically, M. pneumoniae is associated with acute exacerbations of human asthma and a worsening of experimentally induced asthma in mice. Recently, we demonstrated that Community Acquired Respiratory Distress Syndrome (CARDS) toxin, an ADP-ribosylating and vacuolating toxin synthesized by M. pneumoniae, is sufficient to induce an asthma-like disease in BALB/cJ mice. To test the potential of CARDS toxin to exacerbate preexisting asthma, we examined inflammatory responses to recombinant CARDS toxin in an ovalbumin (OVA) murine model of asthma. Differences in pulmonary inflammatory responses between treatment groups were analyzed by histology, cell differentials and changes in cytokine and chemokine concentrations. Additionally, assessments of airway hyperreactivity were evaluated through direct pulmonary function measurements. Analysis of histology revealed exaggerated cellular inflammation with a strong eosinophilic component in the CARDS toxin-treated group. Heightened T-helper type-2 inflammatory responses were evidenced by increased expression of IL-4, IL-13, CCL17 and CCL22 corresponding with increased airway hyperreactivity in the CARDS toxin-treated mice. These data demonstrate that CARDS toxin can be a causal factor in the worsening of experimental allergic asthma, highlighting the potential importance of CARDS toxin in the etiology and exacerbation of human asthma.     

Characterization of pathology and parasite load in outbred and inbred mouse models of chronic Neospora caninum infection

Here, we analyzed histological findings and parasite burden in chronic Neospora caninum infection in BALB/c and ICR mice and studied the correlation between lesion severity and parasite load in brain. To obtain a better understanding of the infection, we examined the influence of various host pathogen factors. Groups of outbred (ICR) and inbred (BALB/c) mice were inoculated using several NC-1 parasite doses (4 x 10(5), 10(6), and 5 x 10(6) tachyzoites), inoculation routes (intraperitoneal and subcutaneous), and 3 immunosuppressive treatments (methylprednisolone, cyclophosphamide, and vinblastine). Lesion severity was analyzed in the liver, lung, heart, and brain tissues, and parasite load was measured by real-time polymerase chain reaction in brain tissue. The results indicated more severe cerebral lesions and higher brain parasite burdens in inbred than in outbred mice. Hepatic tissue was the primary lesion site in immunosuppressed ICR mice. We also observed that increased inoculum size was reflected in greater lesion severity and a higher cerebral parasite load. No difference was observed with respect to inoculation route. The study also showed an association between brain parasite burden and severity of cerebral lesions in BALB/c mice.     

The consequences of inbreeding for recognizing competitors

Extreme inbreeding will compromise an animal's ability to discriminate between individuals and, thus, assess familiarity and kinship with conspecifics. In rodents, a large component of individual recognition is mediated through chemical communication. The counter-marking of competitor males' scent marks provides a measure of discrimination between their own scent and that from other individuals. We investigated whether males in common outbred (ICR(CD-1) and TO) and inbred (BALB/c) strains of laboratory mice could recognize the urinary scents of other individuals by measuring their investigation and counter-marking responses. Dominant males of outbred strains investigated and counter-marked scents from other males, whether of the same or another strain. Dominant inbred BALB/c males investigated but did not counter-mark their own strain scents, counter-marking only those from another strain. They did not use environmentally induced status differences in odours to recognize scents from other males. The inability of the inbred mice to discriminate between their own scent marks and those of other males is likely to alter their competitive behaviour, which could influence responses in experiments and the welfare of caged laboratory mice.     

Anesthetic Effects of a Mixture of Medetomidine,Midazolam and Butorphanol in Two Strains of Mice

The combination of ketamine and xylazine is a widely used anesthetic for laboratory animals. However, due to an abuse problem in Japan, ketamine has been specified as a narcotic since 2007. Instead of using ketamine, Kawai et al. reported an injectable formula with an equivalent effect to the mixture of ketamine and xylazine [11]. The mixture of 0.3 mg/kg body weight (b.w.) medetomidine (Med.), 4.0 mg/kg b.w. midazoram (Mid.), and 5.0 mg/kg b.w. butorphanol (But.) produced an anesthetic duration of around 40 min in outbred ICR mice. However, the anesthetic effect of the mixture for inbred mice strains remains unknown. Therefore, we examined anesthetic effects of the mixture of Med., Mid., and But. in the BALB/c and C57BL/6J strains. After intraperitoneal injection into mice, right front paw, left hind paw, and tail pinch reflexes as well as corneal and righting reflexes were observed. Every 5 min, we scored each reflex category as 0 for reaction or 1 for no reaction. As long as the total score was at least 4 out of 5, we considered the mixture as putting a mouse in a surgical anesthetic state. The mixture produced an anesthetic duration of more than 45 min in both strains of mice. These results indicate that the mixture of Med., Mid., and But. can be a useful and effective anesthesia for the BALB/c and C57BL/6J strains of inbred mice as well as outbred ICR mice.     

Age and strain dependence of O6-methylguanine DNA methyltransferase activity in mice

The activity of the DNA repair protein O6-methylguanine DNA methyltransferase (MT) was compared in liver extracts from female ICR and male C57BL/6 mice at various ages (3-130 weeks old). Similar patterns of overall enzyme activity were observed in both strains with O6-MT activity being relatively low in young mice (3 or 8 weeks old). However, the activity significantly increased after adolescence (middle age), thereafter decreasing with old age (over 100 weeks old) to a level equivalent to that found in young mice. In an additional strain difference study, O6-MT activities in liver extracts from 4 strains of mice were compared at 5 and 30 weeks of age. Although a similar age-associated increase of enzyme activity in adolescence was confirmed in all 4 strains investigated, the closed-colony ICR mice differed from the inbred strains in demonstrating significantly higher levels of O6-MT activity in females than in males. However, the same tendency was also observed in a comparison of the sexes in 30-week-old C3H/HeN, C57BL/6 and BALB/c mice.     

Reversal of thymic stromal lymphopoietin-induced airway inflammation through inhibition of Th2 responses

Lung-specific thymic stromal lymphopoietin (TSLP) expression is sufficient for the development of an asthma-like chronic airway inflammatory disease. However, the nature of the downstream pathways that regulate disease development are not known. In this study, we used IL-4- and Stat6-deficient mice to establish the role of Th2-type responses downstream of TSLP. IL-4 deficiency greatly reduced, but did not eliminate, TSLP-induced airway hyperresponsiveness, airway inflammation, eosinophilia, and goblet cell metaplasia, while Stat6 deficiency eliminated these asthma-like symptoms. We further demonstrate, using the chronic model of TSLP-mediated airway inflammation, that blockade of both IL-4 and IL-13 responses, through administration of an anti-IL-4R alpha mAb, reversed asthma-like symptoms, when given to mice with established disease. Collectively these data provide insight into the pathways engaged in TSLP-driven airway inflammation and demonstrate that simultaneous blockade of IL-4 and IL-13 can reverse established airway disease, suggesting that this may be an effective approach for the therapy of Th2-mediated inflammatory respiratory disease.     

Sleep-time variation for ethanol and the hypnotic drugs tribromoethanol, urethane, pentobarbital, and propofol within outbred ICR mice.

To evaluate the phenotypic variation within a commercial outbred mouse stock, we examined sleep-time (or duration of loss of righting reflex) of outbred ICR mice after i.p. injection of ethanol (4.0 g/kg of body weight), urethane (1.3 g), tribromoethanol (250 mg), and pentobarbital (60 mg), and after i.v. injection of propofol (30 mg). We observed high-grade individual differences in sleep-time that ranged from 0 to 179 min, 83.1 +/- 4.3 (mean and SEM of 100 mice) for ethanol; 0 to 169 min, 64.5 +/- 3.1 for pentobarbital; 0 to 160 min, 36.6 +/- 3.6 for urethane; 0 to 120 min, 21.5 +/- 2.2 for tribromoethanol; and 3 to 20.5 min, 7.1 +/- 0.3 for propofol. This extensive phenotypic variance within the outbred stock was as great as the variation reported among inbred strains or selected lines, and the varied susceptibility within the colony was inherited by Jcl:ICR-derived inbred strains IAI, ICT, IPI, and IQI. The range of sleep-time variance for ethanol, pentobarbital, urethane, tribromoethanol, and propofol within four-way cross hybrid Jcl:MCH(ICR) mice was 86.6%, 63.3%, 124%, 61.0%, and 53.1% that of outbred Jcl:ICR mice, respectively. The present study indicates that phenotypic variance within an outbred Jcl:ICR stock was at high risk for susceptibility to the drugs that depress the central nervous system and that Jcl:ICR-derived inbreds may be an excellent source of animal models for studying the anesthesia gene.     

Neonatal rhinovirus infection induces mucous metaplasia and airways hyperresponsiveness

Recent studies link early rhinovirus (RV) infections to later asthma development. We hypothesized that neonatal RV infection leads to an IL-13-driven asthma-like phenotype in mice. BALB/c mice were inoculated with RV1B or sham on day 7 of life. Viral RNA persisted in the neonatal lung up to 7 d postinfection. Within this time frame, IFN-α, -β, and -γ peaked 1 d postinfection, whereas IFN-λ levels persisted. Next, we examined mice on day 35 of life, 28 d after initial infection. Compared with sham-treated controls, virus-inoculated mice demonstrated airways hyperresponsiveness. Lungs from RV-infected mice showed increases in several immune cell populations, as well as the percentages of CD4-positive T cells expressing IFN-γ and of NKp46/CD335(+), TCR-β(+) cells expressing IL-13. Periodic acid-Schiff and immunohistochemical staining revealed mucous cell metaplasia and muc5AC expression in RV1B- but not sham-inoculated lungs. Mucous metaplasia was accompanied by induction of gob-5, MUC5AC, MUC5B, and IL-13 mRNA. By comparison, adult mice infected with RV1B showed no change in IL-13 expression, mucus production, or airways responsiveness 28 d postinfection. Intraperitoneal administration of anti-IL-13 neutralizing Ab attenuated RV-induced mucous metaplasia and methacholine responses, and IL-4R null mice failed to show RV-induced mucous metaplasia. Finally, neonatal RV increased the inflammatory response to subsequent allergic sensitization and challenge. We conclude that neonatal RV1B infection leads to persistent airways inflammation, mucous metaplasia, and hyperresponsiveness, which are mediated, at least in part, by IL-13.     

Egg production of Clonorchis sinensis in different strains of inbred mice.

In order to compare the intraspecific variation in host-parasite relationship of Clonorchis sinensis, six strains of inbred mice, ICR, DDY, GPC, BALB/c, nude and DS, were infected orally with 20 metacercariae of C. sinensis. The biologic incubation period of C. sinensis was the shortest in DDY mice, 21.2 days in average, followed by GPC 21.4, BALB/c and DS 23.2, ICR and nude 23.4 days, respectively. The fertile period of the fluke was also the longest in the DDY strain, 164 days on average, followed by GPC 132, BALB/c 97, nude 37, DS 32 and ICR 28 days. The egg-laying capacity of the fluke in DDY and GPC was relatively high and stable compared with the other four strains of mice. It was found that there are intraspecific variations in biologic incubation period, fertile period, and fecundity of C. sinensis. The DDY mouse is likely to be the most suitable experimental animal among the six strains of the mice tested.     

Interstrain variation in murine susceptibility to inhaled acid-coated particles

Epidemiologic studies have demonstrated a positive correlation between concentration of acid aerosol and increased morbidity and mortality in many urban environments. To determine whether genetic background is an important risk factor for susceptibility to the toxic effects of inhaled particles, we studied the interstrain (genetic) and intrastrain (environmental) variance of lung responses to acid-coated particle (ACP) aerosol in nine strains of inbred mice. A flow-past nose-only inhalation system was used to expose mice to ACPs produced by the cogeneration of a carbon black aerosol-sulfur dioxide (SO(2)) mixture at high humidity. Three days after a single 4-h exposure to ACPs or filtered air, mice underwent bronchoalveolar lavage, and cell differentials and total protein were determined as indexes of inflammation and epithelial permeability, respectively. To determine the effect of ACPs on alveolar macrophage (AM) function, lavaged AMs were isolated from exposed animals and Fc receptor-mediated phagocytosis was evaluated. Compared with air-exposed animals, there was a slight but significant exposure effect of ACPs on the mean number of lavageable polymorphonuclear leukocytes in C3H/HeJ and C3H/HeOuJ mice. ACP exposure also caused a significant decrease in AM phagocytosis. Relative to respective air-exposed animals, Fc receptor-mediated phagocytosis was suppressed in eight of nine strains. The order of strain-specific effect of ACPs on phagocytosis was C57BL/6J > 129/J > SJL/J > BALB/cJ > C3H/HeOuJ > A/J > SWR/J > AKR/J. There was no effect of ACP exposure on AM phagocytosis in C3H/HeJ mice. The significant interstrain variation in AM response to particle challenge indicates that genetic background has an important role in susceptibility. The effects of ACPs on AM function, inflammation, and epithelial hyperpermeability were not correlated (i.e., no cosegregation). This model may have important implications concerning interindividual variation in particle-induced compromise of host defense.     

BALB/c alleles at modifier loci increase the severity of the maternal effect of the "DDK syndrome"

The Om locus was first described in the DDK inbred mouse strain: DDK mice carry a mutation at Om resulting in a parental effect lethality of F(1) embryos. When DDK females are mated with males of other (non-DDK) inbred strains, e.g., BALB/c, they exhibit a low fertility, whereas the reciprocal cross, non-DDK females x DDK males, is fertile (as is the DDK intrastrain cross). The low fertility is due to the death of (DDK x non-DDK)F(1) embryos at the late-morula to blastocyst stage, which is referred to as the "DDK syndrome." The death of these F(1) embryos is caused by an incompatibility between a DDK maternal factor and the non-DDK paternal pronucleus. Previous genetic studies showed that F(1) mice have an intermediate phenotype compared to parental strains: crosses between F(1) females and non-DDK males are semisterile, as are crosses between DDK females and F(1) males. In the present studies, we have examined the properties of mice heterozygous for BALB/c and DDK Om alleles on an essentially BALB/c genetic background. Surprisingly, we found that the females are quasi-sterile when mated with BALB/c males and, thus, present a phenotype similar to DDK females. These results indicate that BALB/c alleles at modifier loci increase the severity of the DDK syndrome.     

野生TW近交系小鼠主要生理指标

目的建立野生来源TW（Tianjin Wild,TW）近交系小鼠的主要生理、血常规等指标。方法分别选用F28和F29代TW近交系成年雄性小鼠25只,雌性小鼠31只,检测动物的主要生理、血常规指标。结果TW小鼠体重雌雄差异无显著性,脏器指标中雌雄性比较仅肾脏重量、肾脏系数差异有显著性（P〈0.05）;血常规检测指标中,雌雄小鼠在WBC、MCV、MCH、PLT、MONO等5项指标的均值比较差异具有显著性,其他各项均无差别。与ICR、KM、NIH及BALB/c等通用实验小鼠指标比较,TW小鼠的脾脏、脾脏系数和血小板均高于或多倍高于这些通用小鼠品系。结论TW小鼠在一些主要生理指标上与通用实验小鼠品系不同,呈现自身特点。     

Genotype-specific environmental impact on the variance of blood values in inbred and F1 hybrid mice

Mice are important models for biomedical research because of the possibility of standardizing genetic background and environmental conditions, which both affect phenotypic variability. Inbred mouse strains as well as F₁ hybrid mice are routinely used as genetically defined animal models; however, only a few studies investigated the variance of phenotypic parameters in inbred versus F₁ hybrid mice and the potential interference of the genetic background with different housing conditions. Thus, we analyzed the ranges of clinical chemical and hematologic parameters in C3H and C57BL/6 inbred mice and their reciprocal F₁ hybrids (B6C3F1, C3B6F1) in two different mouse facilities. Two thirds of the blood parameters examined in the same strain differed between the facilities for both the inbred strains and the F₁ hybrid lines. The relation of the values between inbred and F₁ hybrid mice was also affected by the facility. The variance of blood parameters in F₁ hybrid mice compared with their parental inbred strains was inconsistent in one facility but generally smaller in the other facility. A subsequent study of F₁ hybrid animals derived from the parental strains C3H and BALB/c, which was done in the latter housing unit, detected no general difference in the variance of blood parameters between F₁ hybrid and inbred mice. Our study clearly demonstrates the possibility of major interactions between genotype and environment regarding the variance of clinical chemical and hematologic parameters.     

用不同实验小鼠品系建立精神分裂症的动物模型

基于精神分裂症的谷氨酸功能紊乱假说,实验用N-甲基-D-天门冬氨酸(NMDA)非竞争性受体拮抗剂MK801(5-甲基二氢二苯并环庚稀亚氨马来酸或地卓西平马来酸盐)作用于实验小鼠,观察到类似精神分裂症的症状：移动加快(hyperlocomotion)和刻板性动作(stereotypy),建立了可用仪器测定的两项量化指标。根据作用于近交系BALB/c小鼠的MK801的剂量优化结果,用0．6mg／kg体重的MK801剂量初步建立了精神分裂症小鼠模型,并用近交系C57BL／6小鼠成功重复了上述实验。进一步用系列剂量的MK801作用于远交群ICR小鼠,同样也诱发了类似精神分裂症的症状。用目前临床上常用的抗精神分裂症药物利培酮作用于已建立的BALB／c小鼠和C57BL／6小鼠的精神分裂症模型,结果表明利培酮能显著地抑制两品系模型小鼠的类似精神分裂症的症状。实验结果证明：用MK801作用于实验小鼠建立精神分裂症动物模型是可行的。     

Immunological basis for susceptibility and resistance to pulmonary blastomycosis in mouse strains

The immunological basis for a >10-fold resistance of outbred CD-1 mice compared to inbred BALB/c mice to pulmonary blastomycosis was investigated. Bronchoalveolar macrophages (BAM) from CD-1 mice killed yeast cells of Blastomyces dermatitidis (Bd) by 25% and this increased to 59% when activated by IFN-gamma. In contrast, BAM from BALB/c mice lacked significant killing (5%) of Bd but could be activated by IFN-gamma for enhanced killing (19%). Peritoneal macrophages (PM) from CD-1 mice had significant fungicidal activity for Bd (43%) and this increased to 63% with IFN-gamma treatment. By contrast, PM from BALB/c mice did not significantly kill Bd (14%) but were activated by IFN-gamma for significant killing (24%). Fungicidal activity of peripheral blood polymorphonuclear neutrophils (PMN) from CD-1 (87%) was greater than that of BALB/c (75%) (P<0.05). Macrophage inflammatory protein-1alpha (MIP-1alpha) production by BAM from BALB/c was significantly less than that from CD-1 in response to co-culture with Bd. IFN-gamma production by CD-1 spleen cells in response to concanavalin A (Con A, 1microg/ml) was 8-fold greater than that by BALB/c spleen cells. In contrast, BAM and PM from BALB/c mice in co-culture with Bd secreted several-fold more TNFalpha than BAM or PM from CD-1 mice. IL-2 production by BALB/c spleen cells in response to Con A was 3- to 4-fold greater than that by CD-1 spleen cells. Depressed IL-2 production by Con A stimulated CD-1 spleen cells correlated with depressed proliferative responses. Resistance of CD-1 mice to pulmonary blastomycosis correlates with enhanced fungicidal activity of BAM, PM, PMN, and IFN-gamma production by Con A stimulated spleen cells, compared to BALB/c mice. Consistent with the in vitro enhancement of effector cell function by IFN-gamma, in vivo therapy with IFN-gamma significantly (P<0.0001) improved survival of BALB/c mice with pulmonary blastomycosis.     

Oral tolerance inhibits pulmonary eosinophilia in a cockroach allergen induced model of asthma: a randomized laboratory study

Background

Antigen desensitization through oral tolerance is becoming an increasingly attractive treatment option for allergic diseases. However, the mechanism(s) by which tolerization is achieved remain poorly defined. In this study we endeavored to induce oral tolerance to cockroach allergen (CRA: a complex mixture of insect components) in order to ameliorate asthma-like, allergic pulmonary inflammation.

Methods

We compared the pulmonary inflammation of mice which had received four CRA feedings prior to intratracheal allergen sensitization and challenge to mice fed PBS on the same time course. Respiratory parameters were assessed by whole body unrestrained plethysmography and mechanical ventilation with forced oscillation. Bronchoalveolar lavage fluid (BAL) and lung homogenate (LH) were assessed for cytokines and chemokines by ELISA. BAL inflammatory cells were also collected and examined by light microscopy.

Results

CRA feeding prior to allergen sensitization and challenge led to a significant improvement in respiratory health. Airways hyperreactivity measured indirectly via enhanced pause (Penh) was meaningfully reduced in the CRA-fed mice compared to the PBS fed mice (2.3 ± 0.4 vs 3.9 ± 0.6; p = 0.03). Directly measured airways resistance confirmed this trend when comparing the CRA-fed to the PBS-fed animals (2.97 ± 0.98 vs 4.95 ± 1.41). This effect was not due to reduced traditional inflammatory cell chemotactic factors, Th2 or other cytokines and chemokines. The mechanism of improved respiratory health in the tolerized mice was due to significantly reduced eosinophil numbers in the bronchoalveolar lavage fluid (43300 ± 11445 vs 158786 ± 38908; p = 0.007) and eosinophil specific peroxidase activity in the lung homogenate (0.59 ± 0.13 vs 1.19 ± 0.19; p = 0.017). The decreased eosinophilia was likely the result of increased IL-10 in the lung homogenate of the tolerized mice (6320 ± 354 ng/mL vs 5190 ± 404 ng/mL, p = 0.02).

Conclusion

Our results show that oral tolerization to CRA can improve the respiratory health of experimental mice in a CRA-induced model of asthma-like pulmonary inflammation by reducing pulmonary eosinophilia.