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TLR3 and TLR7 modulate IgE production in antigen induced pulmonary inflammation via influencing IL-4 expression in immune organs.

Meng L, He X, Zhu W, Yang X, Jiang C, Sun Q - PLoS ONE (2011)

Bottom Line: The numbers of total cells, eosinophils, macrophages and lymphocytes were counted according to differential morphology in bronchoalveolar lavage fluid.Serum IgE and OVA specific IgG(1) concentration was detected by enzyme-linked immunosorbent assay.The results showed that both TLR7 ligand treatment and TLR3 RNAi in vivo decreased serum IgE level and interleukin-4 mRNA expression.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics and Molecular Biology, Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi, China.

ABSTRACT

Background: Toll-like receptors (TLRs) as pattern recognition receptors, participate in both innate and adaptive immune responses, and seem to play an important role in the pathogenesis of asthma. This study aimed to identify key TLRs involved in antigen induced pulmonary inflammation (AIPI), a rat model for asthma, and to explore the role of TLRs in the disease development.

Methods and findings: E3 rats were sensitized with ovalbumin (OVA)/alum intraperitoneally and intranasally challenged with OVA to induce AIPI model. TLR1-9 and cytokine mRNA expression in spleen, lung and mediastinal lymph node (mLN) tissues were screened by quantitative real-time polymerase chain reaction. TLR7 expression was found to be significantly down-regulated in spleen while TLR3 and TLR8 expression was up-regulated in mLN of AIPI rats. Furthermore, imiquimod (a ligand of TLR7) and TLR3 specific short-hairpin RNA plasmid for RNA interference were administrated, respectively, in vivo to AIPI rats to observe their effects on the disease by assessing various asthmatic parameters. The numbers of total cells, eosinophils, macrophages and lymphocytes were counted according to differential morphology in bronchoalveolar lavage fluid. Serum IgE and OVA specific IgG(1) concentration was detected by enzyme-linked immunosorbent assay. The results showed that both TLR7 ligand treatment and TLR3 RNAi in vivo decreased serum IgE level and interleukin-4 mRNA expression.

Conclusion/significance: TLR3 in mLN and TLR7 in spleen both systemically modulate disease development in AIPI rats via altering serum IgE concentration relevant to Th2 responses. And these findings may provide an important clue for further research in the asthma pathogenesis and suggest a new remedy for asthma treatment.

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Assessment of various asthmatic parameters in TLR7 agonist stimulated AIPI rats.E3 rats were injected intraperitoneally with vehicle or TLR7 agonist on day 13 and 17 during the period of AIPI induction. The rats of AIPI group (n = 9) received 1 ml saline and the rats of AIPI+imi (imiquimod) group (n = 9) received 100 µg miquimod. TLR7 mRNA and cytokine mRNA expression levels in spleen were measured by QPCR (A). Levels of serum total IgE (B) and OVA-specific IgG1 (C) were measured by ELISA. Total cell numbers in BALF were counted under light microscope using a hemocytometer and values of macrophage, eosinophil and lymphocyte counts in BALF were expressed as the percentage of cell numbers of total cells (D). Results show as mean ±SEM from 9 rats in each group. *P<0.05; **P<0.01; ***P<0.001; significantly different from AIPI group.
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pone-0017252-g004: Assessment of various asthmatic parameters in TLR7 agonist stimulated AIPI rats.E3 rats were injected intraperitoneally with vehicle or TLR7 agonist on day 13 and 17 during the period of AIPI induction. The rats of AIPI group (n = 9) received 1 ml saline and the rats of AIPI+imi (imiquimod) group (n = 9) received 100 µg miquimod. TLR7 mRNA and cytokine mRNA expression levels in spleen were measured by QPCR (A). Levels of serum total IgE (B) and OVA-specific IgG1 (C) were measured by ELISA. Total cell numbers in BALF were counted under light microscope using a hemocytometer and values of macrophage, eosinophil and lymphocyte counts in BALF were expressed as the percentage of cell numbers of total cells (D). Results show as mean ±SEM from 9 rats in each group. *P<0.05; **P<0.01; ***P<0.001; significantly different from AIPI group.

Mentions: To further determine the role of down-regulated TLR7 on asthma development, we investigated whether TLR7 agonist could affect AIPI development. E3 rats were treated with vehicle or imiquimod at indicated time points during AIPI induction, respectively. And various asthmatic parameters were assessed. First we detected TLR7, IL-4, IL-6 and interferon-α (IFN-α) mRNA expression in spleen using QPCR. TLR7 and IFN-α transcripts in spleen tissues were significantly increased after the treatment with imiquimod, while IL-4 mRNA level was markedly decreased (Figure 4A). Furthermore, it was obviously showed that a significant difference was detected in the level of IgE production between groups treated with vehicle and imiquimod (Figure 4B). But imiquimod did not influence OVA-specific IgG1 release (Figure 4B and C). Statistical analysis of cell number counted in BALF (Figure 4D) showed that imiquimod administration only influenced lymphocyte recruitment to the lung. The numbers of total cells, eosinophils and macrophages were unaffected. Taken together, these findings demonstrated that TLR7 agonist mainly influenced serum IgE release and hardly affected other asthmatic parameters.


TLR3 and TLR7 modulate IgE production in antigen induced pulmonary inflammation via influencing IL-4 expression in immune organs.

Meng L, He X, Zhu W, Yang X, Jiang C, Sun Q - PLoS ONE (2011)

Assessment of various asthmatic parameters in TLR7 agonist stimulated AIPI rats.E3 rats were injected intraperitoneally with vehicle or TLR7 agonist on day 13 and 17 during the period of AIPI induction. The rats of AIPI group (n = 9) received 1 ml saline and the rats of AIPI+imi (imiquimod) group (n = 9) received 100 µg miquimod. TLR7 mRNA and cytokine mRNA expression levels in spleen were measured by QPCR (A). Levels of serum total IgE (B) and OVA-specific IgG1 (C) were measured by ELISA. Total cell numbers in BALF were counted under light microscope using a hemocytometer and values of macrophage, eosinophil and lymphocyte counts in BALF were expressed as the percentage of cell numbers of total cells (D). Results show as mean ±SEM from 9 rats in each group. *P<0.05; **P<0.01; ***P<0.001; significantly different from AIPI group.
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getmorefigures.php?uid=PMC3045401&req=5

pone-0017252-g004: Assessment of various asthmatic parameters in TLR7 agonist stimulated AIPI rats.E3 rats were injected intraperitoneally with vehicle or TLR7 agonist on day 13 and 17 during the period of AIPI induction. The rats of AIPI group (n = 9) received 1 ml saline and the rats of AIPI+imi (imiquimod) group (n = 9) received 100 µg miquimod. TLR7 mRNA and cytokine mRNA expression levels in spleen were measured by QPCR (A). Levels of serum total IgE (B) and OVA-specific IgG1 (C) were measured by ELISA. Total cell numbers in BALF were counted under light microscope using a hemocytometer and values of macrophage, eosinophil and lymphocyte counts in BALF were expressed as the percentage of cell numbers of total cells (D). Results show as mean ±SEM from 9 rats in each group. *P<0.05; **P<0.01; ***P<0.001; significantly different from AIPI group.
Mentions: To further determine the role of down-regulated TLR7 on asthma development, we investigated whether TLR7 agonist could affect AIPI development. E3 rats were treated with vehicle or imiquimod at indicated time points during AIPI induction, respectively. And various asthmatic parameters were assessed. First we detected TLR7, IL-4, IL-6 and interferon-α (IFN-α) mRNA expression in spleen using QPCR. TLR7 and IFN-α transcripts in spleen tissues were significantly increased after the treatment with imiquimod, while IL-4 mRNA level was markedly decreased (Figure 4A). Furthermore, it was obviously showed that a significant difference was detected in the level of IgE production between groups treated with vehicle and imiquimod (Figure 4B). But imiquimod did not influence OVA-specific IgG1 release (Figure 4B and C). Statistical analysis of cell number counted in BALF (Figure 4D) showed that imiquimod administration only influenced lymphocyte recruitment to the lung. The numbers of total cells, eosinophils and macrophages were unaffected. Taken together, these findings demonstrated that TLR7 agonist mainly influenced serum IgE release and hardly affected other asthmatic parameters.

Bottom Line: The numbers of total cells, eosinophils, macrophages and lymphocytes were counted according to differential morphology in bronchoalveolar lavage fluid.Serum IgE and OVA specific IgG(1) concentration was detected by enzyme-linked immunosorbent assay.The results showed that both TLR7 ligand treatment and TLR3 RNAi in vivo decreased serum IgE level and interleukin-4 mRNA expression.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics and Molecular Biology, Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi, China.

ABSTRACT

Background: Toll-like receptors (TLRs) as pattern recognition receptors, participate in both innate and adaptive immune responses, and seem to play an important role in the pathogenesis of asthma. This study aimed to identify key TLRs involved in antigen induced pulmonary inflammation (AIPI), a rat model for asthma, and to explore the role of TLRs in the disease development.

Methods and findings: E3 rats were sensitized with ovalbumin (OVA)/alum intraperitoneally and intranasally challenged with OVA to induce AIPI model. TLR1-9 and cytokine mRNA expression in spleen, lung and mediastinal lymph node (mLN) tissues were screened by quantitative real-time polymerase chain reaction. TLR7 expression was found to be significantly down-regulated in spleen while TLR3 and TLR8 expression was up-regulated in mLN of AIPI rats. Furthermore, imiquimod (a ligand of TLR7) and TLR3 specific short-hairpin RNA plasmid for RNA interference were administrated, respectively, in vivo to AIPI rats to observe their effects on the disease by assessing various asthmatic parameters. The numbers of total cells, eosinophils, macrophages and lymphocytes were counted according to differential morphology in bronchoalveolar lavage fluid. Serum IgE and OVA specific IgG(1) concentration was detected by enzyme-linked immunosorbent assay. The results showed that both TLR7 ligand treatment and TLR3 RNAi in vivo decreased serum IgE level and interleukin-4 mRNA expression.

Conclusion/significance: TLR3 in mLN and TLR7 in spleen both systemically modulate disease development in AIPI rats via altering serum IgE concentration relevant to Th2 responses. And these findings may provide an important clue for further research in the asthma pathogenesis and suggest a new remedy for asthma treatment.

Show MeSH
Related in: MedlinePlus