Impact of Mycobacterium vaccae immunization on lung histopathology in a murine model of chronic asthma

BACKGROUND: Therapeutic modalities of asthma have not been proved to be successful in reversing the already established chronic changes of airways. OBJECTIVE: We aimed to determine the impact of heat-killed Mycobacterium vaccae immunization, a potent Th1 stimulant, on chronic changes of asthma. METHODS: Newborn BALB/c mice were divided into three groups; mice in M. vaccae group received 107 colony-forming units (CFU)/50 micro L of heat-killed M. vaccae subcutaneously on days 3, 14 and 42 before the development of chronic asthma model, whereas mice in control and chronic asthma groups received saline. Subsequently, mice in M. vaccae and chronic asthma groups were administered 10 micro g/100 micro L of ovalbumin (OVA) on days 43, 45, 47, 49, 51, 53 and 55 intraperitoneally, and 20 micro g/10 micro L of OVA on days 83, 86 and 89 intratracheally. Mice in control group received saline on the same days. RESULTS: Comparison of M. vaccae and chronic asthma groups showed statistically significant differences in goblet cell numbers, thickness of basement membrane and subepithelial smooth muscle of small, medium and large airways and epithelial thickness of medium airways. There was no significant difference between the control and M. vaccae groups except for goblet cell numbers of medium and large airways, and epithelial thickness of medium airways. CONCLUSION: Results of our study suggested that immunization by M. vaccae of newborn mice would prevent some of the chronic changes of airways due to asthma.     

The role of L-carnitine in treatment of a murine model of asthma

Leukotrienes, one of the mediators of inflammation in asthma, have a strong bronchoconstrictive effect. L-carnitine has been reported to influence respiratory functions. It has also been reported that L-carnitine inhibits leukotriene synthesis. To evaluate the effects of L-carnitine on oxygen saturation, urine leukotriene E4 levels and lung histopathology in a murine model of asthma, high IgE responder BALB/c mice (n = 24) were systemically sensitized to ovalbumin and chronically challenged with low particle mass concentrations of aerosolized ovalbumin, and then they were divided into 3 groups (study groups A, B, and C) each including eight mice. After methacholine-induced bronchoconstriction, the mice in groups A and B were given intraperitoneal L-carnitine (250 and 125 mg/kg, respectively), while the mice in group C were given placebo. Oxygen saturation of the mice was measured by pulse oxymeter before and after methacholine and after L-carnitine/ placebo application. In addition, urine leukotriene E4 levels were measured before asthma development, and 24-h after L-carnitine injection in asthmatic mice. Inflammation in the lung tissues of the sacrificed animals was scored histopathologically to determine the effect of L-carnitine on tissue level. A control group of non-sensitized mice (n = 8) treated with placebo only was used for comparison of urine leukotriene E4 levels and of histopathological parameters. Oxygen saturation of the mice in the study groups tended to decrease after methacholine and to improve after L-carnitine injection, although these changes were not significant at all time points. Urine leukotriene E4 levels of all 3 study groups increased significantly after asthma development. The rate of increment was smallest in the group given the highest L-carnitine dose (group A). Inflammation at the tissue level was also mildest in group A, and severest in the group that was not given carnitine (group C). All of the study groups and the control group differed significantly with respect to inflammation scores. In conclusion, L-carnitine improved oxygen saturation, and decreased urine leukotriene E4 levels and inflammation in lung tissues in the present murine model of asthma.     

Intragastric administration of Mycobacterium vaccae inhibits severe pulmonary allergic inflammation in a mouse model

BACKGROUND: Coexistence with harmless microorganisms such as lactobacilli, saprophytic mycobacteria and some helminths, throughout evolution, may have shaped the host immune system. Exposure to such organisms may have therapeutic benefits by triggering immunoregulatory mechanisms that control inappropriate immune responses to self, gut contents or allergens. OBJECTIVE: We determined whether treatment with Mycobacterium vaccae by gavage influences the host immune response both locally and systemically. We also investigated whether delivery by this route prevents severe symptoms of disease in a murine model of pulmonary allergic inflammation. RESULTS: A single intragastric administration of M. vaccae induced a transient increase in the production of IL-10 and IFN-gamma by mesenteric lymph nodes cells and splenocytes. In addition, in a mouse model of pulmonary allergic inflammation, a single treatment with M. vaccae by gavage not only diminished the total cellular infiltrate and the eosinophilic component induced by subsequent intratracheal allergen challenge, but also biased local and systemic cytokine production towards IL-10. Delivery of M. vaccae by gavage was as effective as subcutaneous treatment. CONCLUSION: This is the first report to suggest that heat-killed mycobacteria can down-regulate symptoms of allergic inflammation by the intragastric route. These data suggest an alternative route of treatment with M. vaccae for patients with allergic conditions.     

The effect of allergen-induced airway inflammation on airway remodeling in a murine model of allergic asthma

OBJECTIVE AND DESIGN: We examined the effect of airway inflammation on airway remodeling and bronchial responsiveness in a mouse model of allergic asthma. MATERIALS AND METHODS: BALB/c mice were sensitized to ovalbumin (OA), and exposed to aerosolized OA (0.01, 0.1 and 1%). Twenty-four hours after the final antigen challenge, bronchial responsiveness was measured, and bronchoalveolar lavage (BAL) and histological examinations were carried out. RESULTS: Repeated antigen exposure induced airway inflammation, IgE/IgG1 responses, epithelial changes, collagen deposition in the lungs, subepithelial fibrosis associated with increases in the amount of transforming growth factor (TGF)-beta1 in BAL fluid (BALF), and bronchial hyperresponsiveness to acetylcholine. The number of eosinophils in BALF was significantly correlated with TGF-beta1 production in BALF and the amount of hydroxyproline. Furthermore, significant correlations were found between these fibrogenic parameters and the bronchial responsiveness. CONCLUSION: These findings demonstrated that in this murine model airway eosinophilic inflammation is responsible for the development of airway remodeling as well as bronchial hyperresponsiveness in allergic bronchial asthma.     

阻断CD28-CD86共刺激途径抑制小鼠气道炎症的研究

TH2淋巴细胞及其分泌的细胞因子在哮喘发病过程中起关键作用。T细胞激活需要由APC表面的共刺激分子与T细胞表面的共刺激分子受体结合形成的共刺激信号。已经公认T淋巴细胞表面的CD28／CTLA4与APC表面的B7-1(CDS0)、B7-2(CD86)是产生共刺激信号的主要分子。本实验旨在探讨抗CD86单克隆抗体对小鼠哮喘模型气道炎症的影响。     

Induction of a type 1 immune response to a recombinant antigen from Mycobacterium tuberculosis expressed in Mycobacterium vaccae.

A 19-kDa lipoprotein from Mycobacterium tuberculosis was expressed as a recombinant antigen in the nonpathogenic mycobacterial host strain M. vaccae. Immunization of mice with the recombinant M. vaccae resulted in induction of a strong type 1 immune response to the 19-kDa antigen, characterized by immunoglobulin G2a (IgG2a) antibodies and gamma interferon (IFN-gamma) production by splenocytes. Immunization with the same antigen in incomplete Freund's adjuvant induced a strong IgG1 response with only low levels of IFN-gamma. Subsequent intravenous and aerosol challenges of immunized mice with virulent M. tuberculosis demonstrated no evidence of protection associated with the response to the 19-kDa antigen; in fact, the presence of the recombinant 19-kDa antigen abrogated the limited protection conferred by M. vaccae (vector control). The recombinant M. vaccae system is a convenient approach to induction of type 1 responses to M. tuberculosis antigens. However, the unexpected reduction in protective efficacy of M. vaccae expressing the 19-kDa antigen highlights the complexity of testing recombinant subunit vaccines and the need for a better understanding of the immune mechanisms required for effective vaccination against tuberculosis.     

蟑螂变应原诱导小鼠肺部变应性炎症动物模型的研究

目的建立美洲大蠊提取液（CAE）诱导的小鼠变应性气道炎症动物模型。方法24只Balb／c小鼠随机分为正常对照组（C组）和美洲大蠊粗浸液2个剂量组：低剂量50μg组（A组）、高剂量100μg组（B组）,8只／组。通过HE染色和PAS染色观察小鼠肺部炎症和黏液分泌;观察支气管肺泡灌洗液中细胞总数和细胞分类;用酶联免疫吸附试验检测BALF、脾细胞培养上清液的细胞因子和血清CAE特异的IgE、IgG1、IgG2a抗体。结果A、B组与对照组C组比较,可诱导肺组织出现明显的气道变态反应性炎症,肺组织炎症病理评分有显著性差异（P〈0．01）;BALF中的细胞总数、EOS计数、中性粒细胞数、IL-4,血清抗原特异性IgE抗体、IgG1抗体和脾细胞分泌IL-4均显著高于正常对照组C组（P〈0．01）;且BALF中的嗜酸性粒细胞计数和IL-4水平与美洲大蠊粗浸液的使用剂量有关（P〈0．01）。结论美洲大蠊提取液能成功建立小鼠变态反应气道炎症动物模型,且呈剂量依赖性,高剂量能更有效诱导气道变态反应性炎症。     

Correlation of histopathologic and bacteriologic changes with cytokine expression in an experimental murine model of bacteremic Staphylococcus aureus infection.

Staphylococcus aureus infections are often life threatening. Relatively little is known about the host response to these infections, in particular, the role played by cytokines. We established a mouse model of bacteremic S. aureus infection to correlate bacteriologic findings and pathologic changes with cytokine gene expression. Bacterial density in blood and tissue was highest at 1 h and minimal by 48 h. Despite the rapid clearance of bacteria, pathologic abnormalities and inflammatory cytokines were detected after clearance of the bacteria. The number of infiltrating inflammatory cells, as well as the size of inflammatory foci, increased with time. Interstitial accumulation of inflammatory cells and tissue damage, such as microabscesses, edema, and necrosis progressed following clearance of bacteria from the tissues. Levels of tumor necrosis factor and interleukin-1 protein in serum were detectable at 1 h and peaked at 4 h. Interleukin-6 protein expression showed different kinetics, with low levels detected at 1 h and increasing levels at 72 h postinfection. Tumor necrosis factor and the interleukins were expressed in inflammatory and noninflammatory cells in lung, liver, and heart tissues. Leukocytes in the infected tissues were highly reactive with antibodies to the three cytokines, suggesting that activated leukocytes are a major source of inflammatory cytokines after staphylococcal infection. Expression of interleukin-1 and interleukin-6 in tissue-specific cells and endothelial cells was also detected in infected tissues, indicating that cells other than leukocytes contribute to the elevated cytokine levels in this model. Once initiated, expression of inflammatory cytokines contributes to the pathogenesis of S. aureus disease.     

Sex-related splenocyte function in a murine model of allergic asthma

Background The prevalence and severity of asthma are higher among boys than girls, but the ratios are reversed after puberty. These observations strongly suggest that sex hormones have a role in the pathogenesis of the disease. However, the mechanisms underlying the gender differences in asthma are not fully understood.
Objective The aim of this study was to investigate sex differences in allergic inflammation in terms of immune function.
Methods Male and female C57BL/6 mice were sensitized and challenged with ovalbumin (OVA). OVA-specific IgE in serum and airway inflammation were compared between sexes. Splenocytes from OVA-sensitized male or female donor mice were transferred to male or female naïve recipient mice. Subsequently, the recipient mice were challenged, followed by the evaluation of OVA-specific IgE and airway inflammation. Cytokines secreted from splenocytes of the sensitized mice were measured.
Results The levels of OVA-specific IgE and the allergen-induced airway inflammation were higher in female than in the male mice. The contents of T-helper type 2 (Th2) cytokines, IL-4, IL-5 and IL-13, in the bronchoalveolar lavage fluid from female mice were higher than those from male mice. The airway inflammation in female recipients transferred with splenocytes from female donors was more severe than that in any other combination of recipients and donors. Splenocytes from the sensitized female mice produced more of the Th2 cytokine, IL-5, than those from the sensitized male mice upon stimulation with OVA.
Conclusion Our findings suggest that the sex difference in allergic airway inflammation may be attributable to the sex difference in not only the hormonal environment but also in the immune cells themselves.     

Pathogenesis of mucous cell metaplasia in a murine asthma model

Increased mucus production in asthma is an important cause of airflow obstruction during severe exacerbations. To better understand the changes in airway epithelium that lead to increased mucus production, ovalbumin-sensitized and -challenged mice were used. The phenotype of the epithelium was dramatically altered, resulting in increased numbers of mucous cells, predominantly in the proximal airways. However, the total numbers of epithelial cells per unit area of basement membrane did not change. A 75% decrease in Clara cells and a 25% decrease in ciliated cells were completely compensated for by an increase in mucous cells. Consequently, by day 22, 70% of the total epithelial cell population in the proximal airways was mucous cells. Electron microscopy illustrated that Clara cells were undergoing metaplasia to mucous cells. Conversely, epithelial proliferation, detected with 5-chloro-2-deoxyuridine immunohistochemistry, was most marked in the distal airways. Using ethidium homodimer cell labeling to evaluate necrosis and terminal dUTP nick-end labeling immunohistochemistry to evaluate apoptosis, this proliferation was accompanied by negligible cell death. In conclusion, epithelial cell death did not appear to be the stimulus driving epithelial proliferation and the increase in mucous cell numbers was primarily a result of Clara cell metaplasia.     

The effect of the beige mutation on infection with murine cytomegalovirus: histopathologic studies.

The tissue damage induced by murine cytomegalovirus (MCMV) in mice with the beige mutation (bg/bg) and in their normal littermates (bg/ +) was investigated. The beige mutation in mice is a homolog of the Chédiak-Higashi syndrome in man, and various dysfunctions of phagocytes and decreased activity of natural killer cells have been demonstrated in these animals. Tissue damage, especially in the liver and spleen, was more conspicuous in bg/bg than in bg/ + mice and was associated with frequent intranuclear inclusions and a higher titer of virus. However, the mutation did not appear to alter the organ distribution of tissue damage induced by MCMV. The inflammatory response in the liver, which is presumed to contribute to host resistance, appeared under certain circumstances to be delayed and deficient in bg/bg mice.     

强力霉素降低哮喘小鼠肺血管通透性

支气管哮喘是常伴有血管通透性和血浆渗漏增加的慢性气道炎症性疾病。血管内皮生长因子(vascu lar endothelialgrowth factor,VEGF)是一种促进血管形成和引起强烈炎症反应的、多功能的细胞因子,可暂时性增加血管的通透性和血管内皮细胞的移行。近年来实验研究表明,VEGF对支气管炎症形成和支气管壁重塑有着非常重要的作用,对哮喘的治疗有重要的研究价值[1]。本研究主要探讨在小鼠哮喘模型中强力霉素对VEGF水平和肺血管通透性的影响。1材料与方法1·1实验分组、模型建立和给药:无特异病原体影响的6~8周龄雄性BalB/c小鼠24只(延边大学实…     

CpG-oligodeoxynucleotides inhibit airway remodeling in a murine model of chronic asthma

BACKGROUND: We have previously demonstrated that CpG oligodeoxynucleotides (CpG-ODNs) protect against eosinophilia and airway hyperresponsiveness in murine models of allergen-induced asthma. Acute inflammation is hypothesized to induce chronic airway responses, but no previous studies have evaluated the effects of CpG-ODNs on allergen-induced airway remodeling. Because remodeling is thought to be responsible for many of the long-term adverse effects on asthmatic patients, we evaluated whether CpG-ODNs might similarly prevent these changes using a murine model of recurrent allergen exposure. OBJECTIVE: The purpose of this study was to evaluate the effect of CpG-ODNs on chronic inflammatory changes and airway remodeling by using a murine model of chronic allergen-induced asthma. METHODS: C57BL/6 mice were sensitized to ovalbumin (OVA) and subsequently exposed to nebulized OVA by means of inhalation 3 times weekly for 6 weeks. Some mice received CpG-ODNs by means of intraperitoneal injection at the time of sensitization. At the end of the exposure period, mice were evaluated for the development of airway inflammation, airway hyperresponsiveness, and airway remodeling. RESULTS: OVA-sensitized mice exposed to recurrent airway challenge with OVA have chronic inflammation, persistent airway hyperresponsiveness, and evidence of airway remodeling, including subepithelial collagen deposition and goblet cell hyperplasia-metaplasia. These changes are significantly reduced in mice treated with CpG-ODNs. Interestingly, mice treated with CpG-ODNs exhibit increased levels of bronchoalveolar lavage transforming growth factor beta, suggesting that regulatory T cells might be responsible for some of these protective effects. CONCLUSION: CpG-ODNs are effective not only in preventing acute inflammation but also appear to reduce markers of airway remodeling that develop after chronic allergen exposure.     

PI3K信号通路对哮喘小鼠调节性T细胞与Th17失衡的调控作用

目的: 探讨PI3K信号通路对哮喘小鼠T细胞中辅助性T细胞17(Th17)与CD4⁺CD 25⁺调节性T细胞(Treg)失衡的调控作用。方法: 尼龙毛柱法分选对照组和哮喘组BALB/c小鼠脾脏T细胞,进而在细胞水平分组:对照组(A组)分为2个亚组:空白对照组(A1),PI3K抑制剂LY294002对照组(A2);哮喘组(B组)继续分为4个亚组:哮喘组(B1),5 μmol/L PI3K抑制剂LY294002组(B2),10 μmol/L PI3K抑制剂LY294002组(B3),20 μmol/L PI3K抑制剂LY294002组(B4),共培养72 h,采用流式细胞仪检测CD4⁺CD 25⁺Treg的数量,酶联免疫吸附反应(ELISA)检测上清中白细胞介素(IL)-10和IL-17水平,逆转录-聚合酶链反应(RT-PCR)检测转录因子Foxp3和RORγt的mRNA水平。结果: (1)分选后获得的T细胞纯度为(74.12±3.08)%,细胞存活率为(92.82±3.21)%;(2)Treg的数量B1组较A1组显著降低(P<0.01);A2组显著高于A1组(P<0.05);B3和B4组较B1组显著增高(均P<0.01);(3)IL-17水平和RORγt mRNA表达B1组较A1组显著增高(P<0.01);A2组显著低于A1组(P<0.01,P<0.05);B2、B3、B4组均显著低于B1组(均P<0.01),呈剂量依赖性降低;而IL-10水平和Foxp3 mRNA表达B1组显著低于A1组(P<0.01); A2组显著高于A1组(P<0.01);B2、B3和B4组均显著高于B1组(P<0.01),且呈浓度依赖性增高;(4)RORγt/Foxp3 mRNA的比值B1组显著高于A1组(P<0.01);A2组显著低于A1组(P<0.01);B2、B3和B4组显著低于B1组(P<0.01),且呈浓度依赖性降低;RORγt/Foxp3 mRNA比值与IL-17水平呈正相关(r=0.89,P<0.01);RORγt/Foxp3 mRNA比值与IL-10呈负相关(r=-0.86,P<0.01)。结论: 哮喘小鼠存在Th17/Treg失衡,PI3K信号通过调控Treg/Th17失衡而参与哮喘发病过程。     

Strain-dependent protective effect of adult thymectomy on murine infection by Mycobacterium lepraemurium.

C57BL/6, DBA/2, BALB/c and CBA mice were thymectomized as adults, or sham-thymectomized, and infected subcutaneously with 10(6) MLM. The number of MLM in the spleen and in the inoculated footpad was measured after 1 year of infection as well as the DTH reactions and the IgM and IgG antibody levels to MLM. Non-thymectomized mice exhibited a broad spectrum of resistance to MLM infection and of T cell mediated immunity grading from the highly resistant C57BL/6 strain to the highly susceptible CBA strain. In between, DBA/2 was found more resistant than BALB/c mice. Adult thymectomy reduced by 100 times the MLM number in the spleen of infected DBA/2 mice, without affecting that measured in the inoculated footpad, and significantly decreased DTH reaction in the same strain. No effect of adult thymectomy was observed in any other strain, except for an increase of anti MLM antibodies in BALB/c mice. These results may suggest that the medium-resistant DBA/2 strain develops after MLM infection suppressor T cells which favour MLM dissemination and are sensitive to adult.     

Critical role of CD23 in allergen-induced bronchoconstriction in a murine model of allergic asthma.

CD23-deficient and anti-CD23 monoclonal antibody-treated mice were used to investigate the role of the low-affinity receptor for IgE (CD23) in allergic airway inflammation and airway hyperresponsiveness (AHR). While there were no significant differences in ovalbumin (OVA)-specific IgE titers and tissue eosinophilia, evaluation of lung function demonstrated that CD23-/- mice showed an increased AHR to methacholine (MCh) when compared to wild-type mice but were completely resistant to the OVA challenge. Anti-CD23 Fab fragment treatment of wild-type mice did not affect the MCh-induced AHR but significantly reduced the OVA-induced airway constriction. These results imply a novel role for CD23 in lung inflammation and suggest that anti-CD23 Fab fragment treatment may be of therapeutic use in allergic asthma.