IL-24 deficiency protects mice against bleomycin-induced pulmonary fibrosis by repressing IL-4-induced M2 program in macrophages.

Idiopathic pulmonary fibrosis (IPF) is the most common type of idiopathic interstitial pneumonia and has one of the poorest prognosis. However, the molecular mechanisms underlying IPF progression remain largely unknown. In this study, we determined that IL-24, an IL-20 subfamily cytokine member, was increased both in the serum of IPF patients and the bronchoalveolar lavage fluid (BALF) of mice following bleomycin (BLM)-induced pulmonary fibrosis. As a result, IL-24 deficiency protected mice from BLM-induced lung injury and fibrosis. Specifically, loss of IL-24 significantly attenuated transforming growth factor ß1 (TGF-ß1) production and reduced M2 macrophage infiltration in the lung of BLM-induced mice. Mechanistically, IL-24 alone did not show a perceptible impact on the induction of M2 macrophages, but it synergized with IL-4 to promote M2 program in macrophages. IL-24 suppressed IL-4-induced expression of suppressor of cytokine signaling 1 (SOCS1) and SOCS3, through which it enhanced signal transducer and activator of transcription 6/peroxisome proliferator-activated receptor gamma (STAT6/PPARγ) signaling, thereby promoting IL-4-induced production of M2 macrophages. Collectively, our data support that IL-24 synergizes with IL-4 to promote macrophage M2 program contributing to the development of pulmonary fibrosis.

[The effect of LPS on airway inflammation, airway remodeling and TLR4 expression in asthmatic rat].

OBJECTIVE: To investigate the effects of lipopolysaccharide (LPS) on airway inflammation, airway remodeling and the expression of Toll-like receptor 4 (TLR4) mRNA in asthmatic rats. METHODS: Twenty-four SPF level SD rats were randomly divided into four groups (n = 6): control group, low dose of LPS group, high dose of LPS group and asthma group. Using ovalbumin (OVA) to sensitize and challenge to establish asthmatic rat model. Observed pathological changes of lung tissue by HE staining, inflammatory cell infiltration was observed by airway wall eosinophils (EOS) counts; airway resistance was determined; image analysis software was used to determine the thickness of airway wall, detected airway smooth muscle TLR4 expression levels by RT-PCR. RESULTS: The rat airway resistance and the EOS number of airway wall and the thickness of airway wall in asthma group, low dose of LPS group and high dose of LPS group were significantly higher than those in control group (P < 0.01). The above-mentioned parameters of high dose of LPS group showed significantly lower than those in asthma group and low dose of LPS group (P < 0.05). The expression of rat airway smooth muscle TLR4 mRNA in low dose of LPS group and high dose of LPS group were significantly higher than those in asthma group (P < 0.01). And the expression of rat airway smooth muscle TLR4 mRNA in high dose of LPS group was significantly higher than that in low dose of LPS group (P < 0.05). CONCLUSION: TLR4 plays an important role in asthmatic airway inflammation and airway remodeling, LPS may play double-sided regulation in asthmatic airway inflammation and airway remodeling by activated TLR4.

[Effects of TOLL-like receptor 4 on passively sensitized human airway smooth muscle cells proliferation and synthesis and secretion function of TGF-beta1].

OBJECTIVE: To investigate the activation of Toll like receptor 4 (TLR4) on passively sensitized human airway smooth muscle cells (HASMCs) proliferation and the synthesis and secretion function. METHODS: Through the cultivation of primary HASMCs, we studied TLR4 expression on cell surface, cell proliferation and transformation of parturient factor-beta1 (TGF-beta1) in asthma under the condition of synthesis and secretion level by passively sensitized HASMCs with asthma serum. RESULTS: Compared with the control group, in passive sensitized group and TNF-alpha group TLR4 expression were significantly increased (P < 0.01), significantly enhanced proliferation (P < 0.01), total protein concentration, IgE secretion and TGF-beta1 were significantly higher (P < 0.01); and all the above parameters were increased more significantly in TNF group compared with those in the target effect of passively group; and those parameters were significantly reduced in anti-TLR4 antibody group compared with those in the target effect both of passively sensitized group and TNF-alpha group. CONCLUSION: TLR4 on passively sensitized HASMCs activated can induce the excessive proliferation of HASMCs and a large number of synthesis and secretion of TGF-beta1, resulting in changing airway micro-environment, which involved in airway remodeling in asthma.

[Effect of TLR4 on the migration of asthmatic airway smooth muscle cells induced by airway epithelial cells].

OBJECTIVE: To explore the effect of Toll-like receptor 4 (TLR4) activation on the migration of asthmatic airway smooth muscle cell (ASMCs) induced by airway epithelial cells. METHODS: Primary ASMCs were cultured by the method of cell digestion. Cell culture supernatant of RTE cells were collected by TNF-alpha stimulation of epithelial cells. Detected the IL-8 and RANTES levels in the supernatant. The transmembrane migration of asthmatic ASMCs were detected by Modified Boyden chemotaxis chamber. The effect of TLR4 on the migration of asthmatic ASMCs induced by epithelial cells with TLR4 antibody drugs as a tool. RESULTS: The levels of IL-8 and RANTES in the supernatant of TNF-alpha groups were significantly increased, and that in the 20 ng/ml group was significantly higher than other groups (P < 0.01). The transmembrane migration of asthmatic ASMCs groups was increased than that of control group. The transmembrane migration of asthmatic ASMCs from asthma group and TNF-alpha + TLR4 antibody group was significantly decreased compared with that in TNF-alpha group (P < 0.01). The migration of asthma ASMCs from TNF-alpha + TLR4 antibody group was increased than that of asthma group (P < 0.05). CONCLUSION: TLR4 in the surface of asthmatic ASMCs may be activated by cytokines secreted by the airway epithelial cells and enhance the transmembrane migration of asthmatic ASMCs induced by airway epithelial cells so that it plays a role in airway remodeling of asthma.

[Role of toll-like receptor 4 in the asthmatic rat airway smooth muscle cells proliferation and apoptosis].

OBJECTIVE: To explore the role of Toll like receptor 4(TLR4) in the asthmatic rat airway smooth muscle cell (ASMCs) proliferation and apoptosis. METHODS: Established rat model of asthma,isolated and cultured rat ASMCs in asthma, using methods of small molecule RNA interference technology and lipofection method, for small molecule RNA-TLR4 transfection, detected proliferation of ASMCs by MIT minim colorimetry, apoptosis of ASMCs by TUNNEL, the expression of TLR4 protein and mRNA were detected by Western blot and RT-PCR in cells. RESULTS: The proliferation of ASMCs in TNF-alpha group were significantly higher than that in control group and siRNA-TLR4 transfection group and TNF-alpha + siRNA-TLR4 transfection group respectively and the proliferation of ASMCs in siRNA-TLR4 transfction group was lower than that in control group. The apoptosis rate of ASMCs in TNF-alpha group was lower than that in control group, siRNA-TLR4 transfection group and TNF-alpha + siRNA-TLR4 transfection group respectively and the apoptosis rate of ASMCs in siRNA-TLR4 transfection group and TNF-alpha + siRNA-TLR4 transfection group were significantly higher than those in control group. The mRNA and protein expression of TLR4 in control group and TNF-alpha group were significantly higher than those in siRNA-TLR4 transfection group and TNF-alpha + siRNA-TLR4 transfection group. The mRNA and protein expression of TLR4 in TNF-alpha group were significantly higher than those in control group (P < 0.01). CONCLUSION: Activation of TLR4 may contribute to asthmatic airway smooth muscle cell proliferation, inhibiting apoptosis and play an important role in airway remodeling in asthma.

[Effect of triptolide on airway smooth muscle proliferation and the expression of nuclear factor-kappa B, Bcl-2 in asthmatic rats].

OBJECTIVE: To explore the effect of triptolide on airway remodeling and the expression of nuclear factor-kappaB, Bcl-2 in asthmatic rats. METHODS: 40 rats were randomly divided into 5 groups (n = 8): (1) Control group; (2) Asthmatic 4 week group; (3) Asthmatic 6 week group; (4) Therapeutic 4 week group; (5) Therapeutic 6 week group. The airway resistance and eosinophilic inflammation of airway wall were observed. The airway wall thickness (WA/Pi), the bronchial smooth muscle thickness (smooth muscle area/Pi) and the number of bronchial smooth muscle nucleus (N/Pi) were measured by image analysis system. The expression of PCNA, nuclear factor-kappaB and Bcl-2 protein were determined by immunohistochemical staining and Western blot. The expression of Bcl-2 mRNA was determined by reverse transcription-polymerase chain reaction(RT-PCR). RESULTS: (1) The expression of NF-kappaB protein in asthmatic 4 week group and asthmatic 6 week group was significantly higher than that in control group, respectively (P < 0.01). The above-mentioned parameters of therapeutic 6 week group were significantly lower than those of asthmatic 4 week group, asthmatic 6 week group and therapeutic 4 week group, respectively (P < 0.01, P < 0.01 P < 0.05). (2) The expression of Bcl-2 protein and mRNA of asthmatic 4 week group and asthmatic 6 week group were significantly higher than those in control group respectively (P < 0.01). The expression of Bcl-2 protein of therapeutic 6 week group was significantly lower than those of asthmatic 4 week group, asthmatic 6 week group and therapeutic 4 week group respectively (P < 0.05, P < 0.01, P < 0.01), but the expression of Bcl-2 mRNA was significantly higher than the above-mentioned groups respectively (P < 0.01), the expression of Bcl-2 protein and mRNA of therapeutic 6 week group were higher than control group respectively (P < 0.05, P < 0.01). (3) The expression of PCNA protein of asthmatic 4 week group and asthmatic 6 week group were significantly higher than those of control group respectively (P < 0.01). (4) The WA/ Pi, the smooth muscle area/Pi and the N/Pi of asthmatic 4 week group and asthmatic 6 week group were significantly higher than those of control group, respectively (P < 0.01). The above-mentioned parameters of therapeutic 6 week group were significantly lower than those of asthmatic 4 week group, asthmatic 6 week group and therapeutic 4 week group, respectively (P < 0.01). (5) The airway resistance of asthmatic 4 week group and asthmatic 6 week group were significantly higher than those of the control group, respectively (P < 0.01). The above-mentioned parameters of therapeutic 6 week group were significantly lower than those of asthmatic 4 week group, asthmatic 6 week group and therapeutic 4 week group, respectively (P < 0.01, P < 0.01, P < 0.05). CONCLUSION: The proliferation of airway smooth muscle(ASM) is related with apoptosis of airway smooth muscle cells in asthma. NF-kappaB may be involved in the process. Triptolide may prevent apoptosis of ASMCs and decrease the proliferation of ASM by inhibiting the expression of NF-kappaB, Bcl-2.