TLR4 through IFN-ß promotes low molecular mass hyaluronan-induced neutrophil apoptosis.

Intratracheal administration of low molecular mass (LMM) hyaluronan (200 kDa) results in greater neutrophil infiltration in the lungs of TLR4(-/-) mice compared with that in wild-type mice. In general, enhanced neutrophil infiltration in tissue is due to cell influx; however, neutrophil apoptosis also plays an important role. We have assessed the effects of TLR4 in the regulation of neutrophil apoptosis in response to administration of LMM hyaluronan. We found that apoptosis of inflammatory neutrophils is impaired in TLR4(-/-) mice, an effect that depends upon the IFN-ß-mediated TRAIL/TRAILR system. IFN-ß levels were decreased in LMM hyaluronan-treated TLR4-deficient neutrophils. The treatment of inflammatory neutrophils with IFN-ß enhanced the levels of TRAIL and TRAILR 2. LMM hyaluronan-induced inflammatory neutrophil apoptosis was substantially prevented by anti-TRAIL neutralizing mAb. We conclude that decreased IFN-ß levels decrease the activity of the TRAIL/TRAILR system in TLR4-deficient neutrophils, leading to impaired apoptosis of neutrophils and resulting in abnormal accumulation of neutrophils in the lungs of LMM hyaluronan-treated mice. Thus, TLR4 plays a novel homeostatic role in noninfectious lung inflammation by accelerating the elimination of inflammatory neutrophils.

TLR4 is a negative regulator in noninfectious lung inflammation.

Low m.w. hyaluronan (LMW HA) has been shown to elicit the expression of proinflammatory cytokines and chemokines in various cells in vitro. However, the effects of this molecule in vivo are unknown. In this study, we report that intratracheal administration of LMW HA (200 kDa) causes inflammation in mouse lung. A lack of TLR4 is associated with even stronger inflammatory response in the lung as shown by increased neutrophil counts and elevated cytokine and chemokine concentrations. We also demonstrate that TLR4 anti-inflammatory signaling is dependent upon a MyD88-independent pathway. TLR4-mediated IL-1R antagonist production plays a negative regulatory role in LMW HA (200 kDa) induced lung inflammation. These data provide a molecular level explanation for the function of TLR4 in LMW HA (200 kDa)-induced lung inflammation, as inhibition of the beta form of pro-IL-1 promotes an anti-inflammatory response.

Local blockade of TSLP receptor alleviated allergic disease by regulating airway dendritic cells.

Thymic stromal lymphopoietin (TSLP) emerges as a central mediator of T helper cell (Th)2-dominant allergic diseases. However, the role of TSLP receptor (TSLPR) in allergen-induced Th2 priming, and the effects of TSLP signaling blocking on the development of asthma remain unclear. Here we showed that allergen challenge caused a rapid accumulation of TSLP in the airways of asthmatic mice, correlating well with eosinophils counts and interleukin (IL)-5 productions. When TSLP signaling was blocked by intratracheal administration of anti-TSLPR antibody before sensitization, eosinophilic airway inflammation, goblet cell hyperplasia and Th2 cytokines productions were significantly reduced. The alleviating effects of TSLPR blocking were achieved by inhibition of maturation and migration of airway dendritic cells (DCs), as well as their abilities of initiating CD4+T cell responses. Thus, local application of anti-TSLPR prevented Th2-mediated airway inflammation, at least partly, by regulating DCs function, which might be exploited to develop novel treatments for asthma.

WIF-1 promoter region hypermethylation as an adjuvant diagnostic marker for non-small cell lung cancer-related malignant pleural effusions.

PURPOSE: Malignant pleural effusion is an important staging criterion in non-small cell lung cancer (NSCLC). Although cytologic examination remains the major diagnostic tool for NSCLC-related malignant pleural effusion, sometimes other invasive methods maybe required. Aberrant activation of Wnt signaling pathway due to Wnt inhibitory factor-1 (WIF-1) promoter region hypermethylation is common in NSCLC, and can be specifically detected by methylation-specific polymerase chain reaction (MSP). We hypothesized that WIF-1 promoter region MSP can be used to improve the diagnostic yield of NSCLC-related malignant pleural effusion. METHODS: We performed WIF-1 promoter region MSP in 36 definite malignant pleural effusions from consecutive NSCLC patients and 35 pleural effusion specimens of benign origin. Pleural effusion cells were collected for DNA extraction. After bisulfite treatment, DNA was amplified by methylation-specific and unmethylation-specific primers, respectively, to identify the methylation status of WIF-1 promoter region. RESULTS: The results of WIF-1 promoter region MSP were positive in 25 (69.4%) of 36 NSCLC patients with malignant pleural effusion. In addition, the results of WIF-1 promoter region MSP were negative in all 35 patients with pleural effusion of benign origin. The age, gender, and smoking status of patients were not correlated with the methylation status of WIF-1 promoter region in NSCLC-related malignant pleural effusion. CONCLUSIONS: WIF-1 promoter region MSP might be used as an adjuvant tool to complement cytologic examination for the diagnosis of NSCLC-related malignant pleural effusion.

Epidermal growth factor receptor mutations in cells from non-small cell lung cancer malignant pleural effusions.

BACKGROUND: The prevalence of epidermal growth factor receptor (EGFR) mutations in non-small cell lung cancer (NSCLC) patients is about 40-50% in Taiwan, and there are significant correlations between EGFR mutations and clinical responses after gefitinib treatment. For most patients with advanced disease, surgical intervention for tissue sampling is not feasible. We therefore conducted this study to survey EGFR mutations in cells from NSCLC malignant pleural effusions and to evaluate the clinical significance. METHODS: In the present study, malignant pleural effusion cells from 29 NSCLC patients were studied for EGFR mutations. Exons 18, 19, 20, 21 of the EGFR gene were analyzed by polymerase chain reaction (PCR) and automated sequencing. For 11 patients who had received gefitinib therapy, correlations between gefitinib effect and EGFR mutations were also evaluated. RESULTS: EGFR mutations were detected in 12 of 29 specimens (41%). In-frame deletion mutations in exon 19 (8 of 12 specimens, 67%) and missense mutations in exon 21 (3 of 12 specimens, 25%) were the most frequent mutations detected. The frequency of EGFR mutations was significantly higher in gefitinib responders (4/4) than non-responders (1/7) (p = 0.015). CONCLUSION: Our results suggest that detecting EGFR mutations in cells from malignant pleural effusions is a feasible adjunct method to finding the subgroup with favorable response to gefitinib therapy among patients with advanced NSCLC.