Role of Thrombin-Activatable Fibrinolysis Inhibitor in Allergic Bronchial Asthma

Background

Bronchial asthma is an inflammatory disease of the airways. Thrombin-activatable fibrinolysis inhibitor (TAFI) is a carboxypeptidase that besides inhibiting fibrinolysis, also regulates inflammatory processes. The only validated substrate known for TAFI is fibrin. In the present study we evaluated the role of TAFI in bronchial asthma by comparing the development of allergic bronchial asthma between wild-type (WT) and TAFI-deficient mice (KO).

Methods

Asthmatic inflammation was induced by sensitization and challenge with ovalbumin in WT (WT/OVA) and TAFI KO (KO/OVA) mice. WT mice (WT/SAL) and TAFI KO (KO/SAL) were used as controls. Cytokines, markers of inflammation, and coagulation were measured in bronchoalveolar lavage fluid (BALF).

Results

Airway hyperresponsiveness was worse in KO/OVA mice than in WT/OVA mice or control mice. Markers of lung injury were significantly increased in BALF from KO/OVA mice compared to WT/OVA mice. Airway hyperresponsiveness and the BALF concentrations of IL-5 and osteopontin were significantly increased in KO/OVA mice compared to WT/OVA mice. Treatment of WT/OVA and KO/OVA mice with a C5a receptor antagonist significantly decreased hyperresponsiveness along with the BALF concentrations of total protein and C5a compared to untreated asthmatic mice.

Conclusion

The results of this study suggest that TAFI plays a protective role in the pathogenesis of allergic inflammation probably by inhibiting the complement system.     

Toll-like receptors in the respiratory system: Their roles in inflammation

Allergic airway inflammation develops in the context of innate immune cells that express Toll-like receptors (TLRs). TLRs recognize microbial components and evoke diverse responses in immune and other respiratory cells through distinct signaling pathways. Bacterial and viral infection in the airway modulates the extent of allergic inflammation. TLR stimulation controls T helper (Th) 1, Th2, and Th17 cell differentiation, cytokine production in mast cells, and activation of eosinophils via direct and indirect pathways. TLR signals in dendritic cells increase expression of major histocompatibility complex proteins and T-cell coreceptors, resulting in greater T-cell activation with Th1 bias. TLR signals in mast cells increase their release of IL-5, and TLR signals in airway epithelial cells enhance airway generation of proallergic cytokines. Although these responses play an important protective role in infection, they may exacerbate allergic inflammation. Under some conditions, TLR stimulation, especially via TLR9, reduces Th2-dependent allergic inflammation through induction of Th1 responses. Therefore, understanding the regulatory role of TLRs in the pathogenesis of allergic airway inflammation may shed light on improving inflammation control in asthmatic patients.     

外源性间充质干细胞减轻支气管哮喘小鼠气道炎症的研究

目的观察鸡卵清蛋白诱导小鼠支气管哮喘（简称哮喘）模型中外源性间充质干细胞（mesenehymal stem cells,MSC）在哮喘小鼠肺组织气道炎症中的作用。方法45只雌性SPF级C57BL／6小鼠,体质量18-22g。随机分为对照组（P：P：P）、哮喘组（O：P：O）和MSC治疗组（O：M：O）。哮喘组与MSC治疗组第1天和第8天致敏,第15天、第16天和第17天使用OVA气道内滴入激发哮喘。MSC治疗组于哮喘造模第14天移植外源性MSC。对照组小鼠予PBS处理。三组小鼠于末次激发结束后24h（第18天）处死,取支气管肺泡灌洗液上清,ELISA检测IL-5、IL-9及β-氨基己糖苷酶;支气管肺泡灌洗液细胞计数总细胞数、嗜酸粒细胞数;取肺组织行病理切片苏木精-伊红染色观察肺部气道炎症情况。结果①MSC下调了哮喘小鼠气道局部炎症;②MSC减轻了哮喘小鼠肺组织中的炎细胞浸润;③MSC减轻了哮喘小鼠气道中的肥大细胞脱颗粒现象;④MSC抑制了哮喘小鼠过度的Th2变态反应。结论外源性MSC通过抑制Th2变态反应,减轻哮喘肺组织的气道炎症。     

外源性间充质干细胞减轻支气管哮喘小鼠气道炎症的研究

目的 观察鸡卵清蛋白诱导小鼠支气管哮喘(简称哮喘)模型中外源性间充质干细胞(mesenchymal stem cells,MSC)在哮喘小鼠肺组织气道炎症中的作用.方法 45只雌性SPF级C57BL/6小鼠,体质量18～22 g.随机分为对照组(P:P:P)、哮喘组(O:P:O)和MSC治疗组(O:M:O).哮喘组与MSC治疗组第1天和第8天致敏,第15天、第16天和第17天使用OVA气道内滴入激发哮喘.MSC治疗组于哮喘造模第14天移植外源性MSC.对照组小鼠予PBS处理.三组小鼠于末次激发结束后24 h(第18天)处死,取支气管肺泡灌洗液上清,ELISA检测IL-5、IL-9及β-氨基己糖苷酶;支气管肺泡灌洗液细胞计数总细胞数、嗜酸粒细胞数;取肺组织行病理切片苏木精-伊红染色观察肺部气道炎症情况.结果 ①MSC下调了哮喘小鼠气道局部炎症;②MSC减轻了哮喘小鼠肺组织中的炎细胞浸润;③MSC减轻了哮喘小鼠气道中的肥大细胞脱颗粒现象;④MSC抑制了哮喘小鼠过度的Th2变态反应.结论 外源性MSC通过抑制Th2变态反应,减轻哮喘肺组织的气道炎症.     

支气管哮喘持续状态下豚鼠气道感觉神经生长相关蛋白43的表达

目的研究支气管哮喘(简称哮喘)过敏性刺激诱发气道感觉神经敏化机制。方法成年雄性豚鼠39只,按随机数字表法分为生理盐水致敏/激发对照组(A组,9只)、卵白蛋白(OVA)致敏/生理盐水激发对照组(B组,9只)、OVA致敏/激发实验组(C组,21只)。A组以生理盐水(0.5ml/只)致敏,B、C组以10%OVA(0.5ml/只)致敏,第10天开始雾化吸入生理盐水(A、B组)或1%OVA(C组)进行激发,每天1次,每次30min,根据实验需要又将C组21只豚鼠分为激发1d组(C1组,6只)、连续激发3d组(C2组,6只)、连续激发5d组(C3组,9只)。利用免疫荧光双标技术结合激光共聚焦扫描显微观察与Westernblot技术,研究生长相关蛋白43(GAP43)在气道神经以及结状神经节、颈静脉神经节内分布与水平及与P物质(SP)和胶质源神经生长因子(GDNF)受体c RET表达神经元关系。结果免疫荧光结果显示,C3组豚鼠气道内GAP43免疫反应阳性神经呈网状分布于大、中支气管内,以黏膜下层为主,部分GAP43阳性神经纤维向黏膜层内延伸;在结状神经节和颈静脉神经节内有大量GAP43免疫阳性神经胞体,在结状神经节内主要与SP免疫阳性胞体共存,在颈静脉神经节内主要与c RET免疫阳性胞体共存。Westernblot结果显示,A、B、C1、C2、C3组GAP43蛋白表达水平吸光度(A)值分别为0.38±0.04、0.41±0.03、0.49±0.05、0.79±0.08、0.76±0.04。C1、C2、C3组分别与A、B组比较差异均有统计学意义(P均0.05);C2组GAP43蛋白表达与C1组比较差异有统计学意义(P<0.01),但与C3组GAP43蛋白表达比较差异无统计学意义(P>0.05)。结论哮喘过敏性刺激能诱发气道感觉神经———SP肽能神经、GDNF敏感性神经纤维与胞体表达GAP43蛋白。     

Innate immunity conferred by toll‐like receptors 2 and 4 and myeloid differentiation factor 88 expression is pivotal to monosodium urate monohydrate crystal–induced inflammation

Objective

In gout, incompletely defined molecular factors alter recognition of dormant articular and bursal monosodium urate monohydrate (MSU) crystal deposits, thereby inducing self‐limiting bouts of characteristically severe neutrophilic inflammation. To define primary determinants of cellular recognition, uptake, and inflammatory responses to MSU crystals, we conducted a study to test the role of Toll‐like receptor 2 (TLR‐2), TLR‐4, and the cytosolic TLR adapter protein myeloid differentiation factor 88 (MyD88), which are centrally involved in innate immune recognition of microbial pathogens.

Methods

We isolated bone marrow–derived macrophages (BMDMs) in TLR‐2^−/−, TLR‐4^−/−, MyD88^−/−, and congenic wild‐type mice, and assessed phagocytosis and cytokine expression in response to endotoxin‐free MSU crystals under serum‐free conditions. MSU crystals also were injected into mouse synovium‐like subcutaneous air pouches.

Results

TLR‐2^−/−, TLR‐4^−/−, and MyD88^−/− BMDMs demonstrated impaired uptake of MSU crystals in vitro. MSU crystal–induced production of interleukin‐1β (IL‐1β), tumor necrosis factor α, keratinocyte‐derived cytokine/growth‐related oncogene α, and transforming growth factor β1 also were significantly suppressed in TLR‐2^−/− and TLR‐4^−/− BMDMs and were blunted in MyD88^−/− BMDMs in vitro. Neutrophil influx and local induction of IL‐1β in subcutaneous air pouches were suppressed 6 hours after injection of MSU crystals in TLR‐2^−/− and TLR‐4^−/− mice and were attenuated in MyD88^−/− mice.

Conclusion

The murine host requires TLR‐2, TLR‐4, and MyD88 for macrophage activation and development of full‐blown neutrophilic, air pouch inflammation in response to MSU crystals. Our findings implicate innate immune cellular recognition of naked MSU crystals by specific TLRs as a major factor in determining the inflammatory potential of MSU crystal deposits and the course of gouty arthritis.

     

TLR2‐dependent amelioration of allergic airway inflammation by parasitic nematode type II MIF in mice

In our previous studies, the recombinant type II macrophage migration inhibitory factor homologue (rAs‐MIF) secreted from Anisakis simplex suppressed experimental inflammation mouse model through IL‐10 production and CD4⁺CD25⁺Foxp3⁺ T‐cell recruitment. Also, TLR2 gene expression was significantly increased following rAs‐MIF treatment. To know the relation between TLR2 and amelioration mechanisms of rAs‐MIF, we induced allergic airway inflammation by ovalbumin and alum with or without rAs‐MIF under TLR2 blocking systems [anti‐TLR2‐specific antibody (α‐mTLR2 Ab) treatment and using TLR2 knockout mice]. As a result, the amelioration effects of rAs‐MIF in allergic airway inflammation model (diminished inflammation and Th2 response in the lung, increased IL‐10 secretion, CD4⁺CD25⁺Foxp3⁺ T‐cell recruitment) were diminished under two of the TLR2 blocking model. The expression of TLR2 on the surface of lung epithelial cell was significantly elevated by rAs‐MIF treatment or Pam3CSK (TLR2‐specific agonist) treatment, but they might have some competition effect on the elevation of TLR2 expression. In addition, the elevation of IL‐10 gene expression by rAs‐MIF treatment was significantly inhibited by α‐mTLR2 Ab or Pam3CSK pretreatment. In conclusion, anti‐inflammatory effects of the rAs‐MIF on OVA‐induced allergic airway inflammation might be closely related to TLR2.     

Increased IL-4- and IL-17-producing CD8+ cells are related to decreased CD39+CD4+Foxp3+ cells in allergic asthma

Objective: In allergic asthma, regulatory T cell (Treg) number and function are decreased. Antigen-primed CD8⁺ T cells play an indispensable role in the full development of airway inflammation and airway hyper-responsiveness (AHR) occurring in asthma. In this study, we investigated the relationship between subpopulations of CD8⁺ T cells and CD39⁺ Tregs. Methods: Female C57BL/6 mice were used to develop the model of allergic asthma. Experimental mice were immunized with ovalbumin (OVA) by intra-peritoneal (i.p) injection and then challenged with OVA by intra-tracheal administration. Control mice were immunized with vehicle by i.p injection and challenged with OVA. Airway inflammation was determined by histology and AHR was measured by an invasive method. Levels of interferon (IFN)-γ, IL-4, and IL-17 in bronchoalveolar lavage fluid (BALF) were determined by enzyme-linked immunosorbent assay. The frequencies of CD8⁺IFN-γ⁺ cells (Tc1), CD8⁺IL-4⁺ cells (Tc2), CD8⁺IL-17⁺cells (Tc17), and CD39⁺Tregs were measured by flow cytometry. The correlation between CD39⁺Tregs and Tc subsets was analyzed by Pearson’s test. Results: Experimental mice displayed phenotypes of allergic asthma, including inflammatory cell infiltration into the lungs, goblet cell hyperplasia, increased airway resistance, and increased IL-4 and IL-17 in BALF. Compared to control mice, experimental mice displayed lower CD39⁺Tregs and Tc1 but higher Tc2 and Tc17. There was a negative correlation between CD39⁺Tregs and Tc2 or Tc17. Conclusion: In allergic asthma, increased Tc2 and Tc17 are possibly related to insufficient CD39⁺Tregs.     

Nerve growth factor mediated SH2-Bβ/Akt signal pathway activated in allergic airway challenge in mice

Background and objective: Nerve growth factor (NGF) contributes to airway inflammation and bronchoconstriction in allergic asthma. The Src homology 2β/serine/threonine kinase (SH2‐Bβ/Akt) pathway is one of the avenues through which NGF regulates the biological activity of pheochromocytoma (PC)12 cells. It has also been reported that NGF upregulates the expression of SH2‐Bβ in the lung tissue of asthmatic mice. The present study investigated the effects of NGF and SH2‐Bβ on Akt activation during allergic airway challenge. Methods: BALB/c mice were sensitized and challenged with ovalbumin. The effects of NGF and SH2‐Bβ on Akt in allergic airway challenge were assessed by intravenously administering anti‐NGF antibody or a mutant of SH2‐Bβ (R555E) to these mice. Pulmonary histological changes were then assessed and the inflammatory cells in the BAL fluid (BALF) were counted. Additionally, phosphorylated Akt (p‐Akt) expression was determined by fluorescence microscopy, western blotting and quantitative RT‐PCR. Airway resistance was also measured using closed‐type body plethysmography. Results: We observed p‐Akt overexpression in the lungs after allergen challenge by fluorescence microscopy, Western blotting and RT‐PCR, as compared with the control. However, after treatment with anti‐NGF or R555E, p‐Akt levels and allergen‐induced airway inflammation were reduced in comparison with those of allergen‐challenged mice. Anti‐NGF and R555E also decreased airway hyperresponsiveness caused by allergen challenge in response to methacholine (MCH). Conclusions: These results suggest that SH2‐Bβ regulation of Akt partly participates in the NGF‐mediated development of allergic airway challenge.     

Exacerbating effects of PM2.5 in OVA-sensitized and challenged mice and the expression of TRPA1 and TRPV1 proteins in lungs

Objective: To investigate the effects of particulate matter ≤ 2.5 microns (PM2.5) on asthma-related phenotypes and on lung expression of TRPA1 and TRPV1 proteins in a mouse model of asthma. Methods: Female BALB/c mice were utilized to establish 28- and 42-day asthma models. Mice were sensitized with ovalbumin (OVA) and challenged with OVA, OVA plus normal saline (NS), or OVA plus PM2.5 at two doses, 1.6 or 8.0 mg kg^?1. PM2.5 was instilled intratracheally without anesthesia. After the final OVA challenge was performed, 24 hours later, the changes in airway resistance (RI) and lung dynamic compliance (Cdyn) in response to acetylcholine chloride (ACH) were evaluated, and blood, bronchoalveolar lavage fluid (BALF) and lung tissue were taken at that time. The number of eosinophils in blood and various leukocytes in BALF were determined. Lung protein was extracted and probed for TRPA1 and TRPV1 expression. Interleukin (IL)-13, substance P (SP), prostaglandin D₂ (PGD₂) and nerve growth factor (NGF) in BALF were measured by enzyme-linked immunosorbent assay. Results: PM2.5 treated mice showed significantly greater changes in the number of inflammatory cells in blood and BALF, in RI and Cdyn in response to ACH, and in lung histopathology, indicated by inflammatory cell infiltration, thickened bronchial smooth muscles and bronchial mucosa damage, compared to controls. In addition, higher expression of TRPA1 and TRPV1 in lung and IL-13, SP, PGD₂ and NGF in BALF were seen in mice exposed to PM2.5. All effects were most pronounced in mice in the 42-day model. Conclusions: PM2.5 exacerbates effects of asthma in this model, possibly by regulating TRPA1 and TRPV1 and the relevant neurokines.     

Melatonin inhibits MUC5AC production via suppression of MAPK signaling in human airway epithelial cells

Mucus acts as a primary defense system in the airway against various stimuli. However, excess mucus production causes a reduction in lung function via limitation of the airflow in the airway of patients suffering from asthma or chronic obstructive pulmonary disease (COPD). In this study, we evaluated the effects of melatonin on the production of MUC5AC, a major constituent of the mucin that is secreted from the airway, using epidermal growth factor (EGF)‐stimulated NCI‐H292 cells, a human mucoepidermoid carcinoma cell line, and an ovalbumin (OVA)‐induced asthma murine model. Melatonin treatment significantly reduced the mRNA and protein levels of MUC5AC and reduced interleukin (IL)‐6 production in EGF‐stimulated H292 cells. Melatonin markedly decreased the phosphorylation of MAPKs, including ERK1/2, JNK, and p‐38, induced by EGF stimulation. These findings were consistent with the results using MAPK inhibitors. Particularly, co‐treatment with melatonin and a MAPK inhibitor more effectively suppressed MAPK phosphorylation than treatment with a MAPK inhibitor alone, which resulted in a reduction in MUC5AC expression. In the asthma murine model, melatonin‐treated mice exhibited a marked reduction in MUC5AC expression in the airway compared with the OVA‐induced mice. These reductions were accompanied by reductions in proinflammatory cytokine production and inflammatory cell infiltration. Collectively, these findings indicate that melatonin effectively inhibits MUC5AC expression. These effects may be closely associated with the inhibition of MAPK phosphorylation. Furthermore, our study suggests that melatonin could represent a potential therapeutic for chronic airway diseases, such as asthma and COPD.     

Joint damage and inflammation in c‐Jun N‐terminal kinase 2 knockout mice with passive murine collagen‐induced arthritis

Objective

Previous studies have demonstrated that inhibition of c‐Jun N‐terminal kinase (JNK) decreases joint destruction in the rat adjuvant arthritis model. The present study was undertaken to investigate whether selective loss of JNK‐2 function decreases joint destruction in JNK‐2 knockout mice, in order to determine the role of this isoform in inflammatory arthritis.

Methods

Passive collagen‐induced arthritis (CIA) was induced in Jnk2^−/− and wild‐type mice by administering anti–type II collagen antibodies. Arthritis was assessed daily using a semiquantitative clinical scoring system. Fibroblast‐like synoviocytes (FLS) were prepared from Jnk2^−/− and wild‐type mice, and JNK protein expression was determined by Western blot analysis. Matrix metalloproteinase 13 (MMP‐13) expression was determined by Northern blot analysis, and activator protein 1 (AP‐1) binding activity by electromobility shift assay (EMSA).

Results

The JNK protein level in Jnk2^−/− mice with CIA was 22% of that in wild‐type mice with CIA (P < 0.001), and mainly the 46‐kd isoform was expressed in the former group. Surprisingly, clinical arthritis was slightly more severe in the Jnk2^−/− mice. Histologic scores for synovial inflammation were not significantly different. However, Safranin O–stained sections from the Jnk2^−/− mice exhibited significantly less joint damage. Although joint destruction was decreased in Jnk2^−/− mice with CIA, EMSA and Northern blot analysis of total joint extracts revealed similar levels of AP‐1 binding and MMP‐13 expression in Jnk2^−/− and wild‐type mice. The lack of correlation with AP‐1 activity and MMP expression was probably because non‐FLS cells in the joint may express more JNK‐1 than do FLS.

Conclusion

JNK‐2 is a determinant of matrix degradation, but it has little effect on inflammation in arthritis. Complete inhibition of MMP expression and joint destruction will likely require combined JNK‐1 and JNK‐2 inhibition.

     

Inhibition of phosphodiesterase 4 attenuates airway hyperresponsiveness and airway inflammation in a model of secondary allergen challenge

We compared for the first time the therapeutic potential of a specific phosphodiesterase 4 (PDE4) inhibitor, rolipram, with anti-VLA-4 and anti-IL-5 in a model of secondary allergen exposure of previously sensitized and challenged mice. To address these issues, mice were sensitized and challenged with ovalbumin (OVA) (primary challenge). Six weeks later, sensitized/challenged mice were reexposed to OVA (secondary challenge) and airway response (resistance [RL] and dynamic compliance [Cdyn]) to inhaled methacholine was monitored. After secondary OVA challenge, RL significantly increased as did the number of lung inflammatory cells and IL-4 and IL-5 production in bronchoalveolar lavage fluid (BALF). Administration of rolipram, in a dose-dependent manner, significantly prevented both changes in RL and Cdyn, as well as eosinophil, lymphocyte, and neutrophil accumulation in the BALF; IL-4 and IL-5 levels in BALF were also significantly reduced. In contrast, treatment with anti-VLA-4 and anti-IL-5 only prevented changes in RL and eosinophil numbers and IL-5 production in BALF. Further, goblet cell hyperplasia was suppressed only by treatment with rolipram. None of the treatments affected OVA-specific antibody levels. These studies confirm that IL-5 dependent eosinophilic inflammation plays an essential role in the development of certain aspects of airway function after rechallenge of sensitized mice and that lymphocytes and neutrophils are also important in the development of altered airway function. The use of agents that inhibit PDE4 may have an important role in the treatment of asthma in previously sensitized mice.     

Toll-like receptor 4 mediates alcohol-induced steatohepatitis through bone marrow-derived and endogenous liver cells in mice

Background: Excessive alcohol intake causes an increase in intestinal permeability that induces translocation of gut‐derived lipopolysaccharide (LPS) to the portal vein. Increased LPS in the portal vein stimulates Kupffer cells through Toll‐like receptor (TLR) 4 in the liver. Activated TLR4 signaling in Kupffer cells induces various inflammatory mediators including TNF‐α, IL‐1β, and reactive oxygen species, resulting in liver injury. Hepatic stellate cells (HSCs) also express TLR4. This study investigates whether TLR4 on bone marrow (BM)‐derived cells, including Kupffer cells, or non–BM‐derived endogenous liver cells, including HSCs, contributes to the progression of alcohol‐induced steatohepatitis and fibrogenesis in mice. Methods: TLR4 BM chimera (wild‐type [WT] mice with TLR4^?/? BM or TLR4^?/? mice with WT BM) were generated by the combination of liposomal clodronate injection with whole body irradiation and BM transplantation, followed by treatment with intragastric alcohol feeding. Results: WT mice transplanted with WT BM exhibited liver injury, steatosis, inflammation, and a fibrogenic response. Conversely, TLR4^?/? mice with TLR4^?/? BM displayed less steatosis, liver injury, and inflammation. Notably, steatosis, macrophage infiltration, and alanine aminotransferase levels in both TLR4‐chimeric mice showed intermediate levels between WT mice transplanted with WT BM and TLR4^?/? mice transplanted with TLR4^?/? BM. Hepatic mRNA expression of fibrogenic markers (collagen α1(I), TIMP1, TGF‐β1) and inflammatory cytokines (IL‐1β, IL‐6) were markedly increased in WT mice with WT BM, but there was less of an increase in both TLR4‐chimeric mice and in TLR4^?/? mice transplanted with TLR4^?/? BM. Conclusions: TLR4 signaling in both BM‐derived and non–BM‐derived liver cells is required for liver steatosis, inflammation, and a fibrogenic response after chronic alcohol treatment.     

Sirtuin 1 activator SRT1720 suppresses inflammation in an ovalbumin‐induced mouse model of asthma

Background and objective: In asthma, reduced histone deacetylase activity and enhanced histone acetyltransferase activity in the lungs have been reported. However, the precise function of Sirtuin 1 (Sirt1), a class III histone deacetylase, and the effect of the Sirt1 activator SRT1720 on allergic inflammation have not been fully elucidated. Methods: The effect of SRT1720, a synthetic activator of Sirt1, in an ovalbumin (OVA)‐induced asthma mouse model was investigated. The effect of SRT1720 and resveratrol on OVA stimulation in splenocytes from OVA‐sensitized and challenged mice was also examined. Results: In OVA‐sensitized and challenged mice (OVA mice) compared with saline‐sensitized and challenged mice (control mice), Sirt1 messenger RNA expression in the lungs was decreased (P = 0.02), while cellular infiltration, airway eosinophilia and bronchoalveolar lavage (BAL) fluid levels of interleukin (IL)‐4, IL‐5 and IL‐13 were increased (P < 0.01). In OVA mice, SRT1720 treatment decreased total and eosinophil cell counts and IL‐5 and IL‐13 levels in the BAL fluid compared with the vehicle treatment (P < 0.05). In OVA mice, SRT1720 treatment also decreased inflammatory cell lung infiltrates histologically (P = 0.002). Both SRT1720 and resveratrol suppressed OVA‐induced cell proliferation and IL‐6 (P < 0.05) and tumour necrosis factor‐α (TNF‐α) (P < 0.05) production in splenocytes (P < 0.01). Conclusions: The Sirt1 activator SRT1720 suppressed inflammatory cell infiltration and cytokine production in an OVA‐induced mouse model of asthma. SRT1720 and resveratrol suppressed OVA‐induced splenocyte proliferation and TNF‐α and IL‐6 production. Sirt1 activators might have beneficial effects in asthmatics by suppressing inflammation.     

Enhanced Goblet Cell Hyperplasia in HDC Knockout Mice with Allergic Airway Inflammation

BackgroundHistamine is known to have immunoregulatory roles in allergic reactions through histamine receptor 1 (H1R), H2R, H3R and H4R. However, its role in goblet cell hyperplasia in the airways of asthma patients is yet to be clarified.ObjectiveThis study was designed to examine the role of histamine in goblet cell hyperplasia using histamine-deficient mice (Hdc-/- mice) with allergic airway inflammation.MethodsWild-type and Hdc-/- C57BL/6 mice were sensitized with ovalbumin (OVA). After a 2-week exposure to OVA, goblet cell hyperplasia was evaluated. Cell differentials and cytokines in BALF were analyzed. The mRNA levels of MUC5AC and Gob-5 gene were determined quantitatively.ResultsThe number of eosinophils in BALF increased in both the sensitized wild-type mice and Hdc-/- mice with OVA inhalation. In addition, the numbers of alveolar macrophages and lymphocytes in BALF increased significantly in the sensitized Hdc-/- mice with OVA inhalation compared to the wild-type mice under the same conditions. The concentrations of Interleukin-4 (IL-4), IL-5, IL-13, Interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α) and IL-2 in the BALF all increased significantly in both groups compared to those exposed to saline. In particular, the concentration of TNF-α in the Hdc-/- mice exposed to OVA was significantly higher than that in the wild-type mice under the same conditions. The mRNA levels of Gob-5 and MUC5AC, and the ratio of the goblet cells in the airway epithelium significantly increased in Hdc-/- mice exposed to OVA compared to wild-type mice.ConclusionsThese results suggested that histamine may play a regulatory role in goblet cell hyperplasia in allergic airway inflammation.