Alistair Miller

Interleukin-6 promotes pulmonary emphysema associated with apoptosis in mice

The IL-6 cytokine family, which signals via the shared gp130 coreceptor, is linked with the pathogenesis of emphysema. However, the definitive mechanisms by which these cytokines cause emphysema remain ill-defined. We took an in vivo genetic complementation approach to identify the specific IL-6 cytokine family members and gp130-regulated cellular processes that cause emphysema. We used gp130(F/F) mice homozygous for a subtle knock-in mutation in gp130 that deregulates intracellular signaling by the IL-6 cytokine family. The gp130(F/F) mice spontaneously develop emphysema by age 6 months. Within the IL-6 cytokine family, only IL-6 was significantly up-regulated in the lungs of gp130(F/F) mice, and the genetic targeting of IL-6 in gp130(F/F) mice (gp130(F/F):IL-6(-/-)) prevented emphysema. By contrast, the genetic ablation of receptor signaling via IL-11, which like IL-6 signals via a gp130 homodimer and uses the same signaling machinery, failed to ameliorate emphysema in gp130(F/F) mice. Among the disease-associated processes examined, emphysema strongly correlated with elevated alveolar cell apoptosis. Acute (4-day) exposure to cigarette smoke (CS) further augmented the expression of IL-6 in lungs of gp130(F/F) mice, and subchronic (6-week) exposure to CS exacerbated emphysematous and apoptotic changes in the lungs of gp130(F/F) but not gp130(F/F): IL-6(-/-) mice. IL-6 is the main causative agent of IL-6 cytokine family-induced emphysema, and operates to induce apoptosis in the lung. We propose that the discrete targeting of IL-6 signaling may provide an effective therapeutic strategy against human lung disease.

IL6 Trans-signaling Promotes KRAS-Driven Lung Carcinogenesis

Oncogenic KRAS mutations occur frequently in lung adenocarcinoma. The signaling pathways activated by IL6 promote Kras-driven lung tumorigenesis, but the basis for this cooperation is uncertain. In this study, we used the gp130(F/F) (Il6st) knock-in mouse model to examine the pathogenic contribution of hyperactivation of the STAT3 arm of IL6 signaling on KRAS-driven lung tumorigenesis. Malignant growths in the gp130(F/F):Kras(G12D) model displayed features of atypical adenomatous hyperplasia, adenocarcinoma in situ, and invasive adenocarcinoma throughout the lung, as compared with parental Kras(G12D) mice, where STAT3 was not hyperactivated. Among IL6 family cytokines, only IL6 was upregulated in the lung. Accordingly, normalization of pulmonary STAT3 activity, by genetic ablation of either Il6 or Stat3, suppressed the extent of lung cancer in the model. Mechanistic investigations revealed elevation in the lung of soluble IL6 receptor (sIL6R), the key driver of IL6 trans-signaling, and blocking this mechanism via interventions with an anti-IL6R antibody or the inhibitor sgp130Fc ameliorated lung cancer pathogenesis. Clinically, expression of IL6 and sIL6R was increased significantly in human specimens of lung adenocarcinoma or patient serum. Our results offer a preclinical rationale to clinically evaluate IL6 trans-signaling as a therapeutic target for the treatment of KRAS-driven lung adenocarcinoma.

Deregulated Stat3 signaling dissociates pulmonary inflammation from emphysema in gp130 mutant mice

Interleukin (IL)-6 is a potent immunomodulatory cytokine that is associated with emphysema, a major component of chronic obstructive pulmonary disease (COPD). IL-6 signaling via the gp130 coreceptor is coupled to multiple signaling pathways, especially the latent transcription factor signal transducer and activator of transcription (Stat)3. However, the pathological role of endogenous gp130-dependent Stat3 activation in emphysema is ill defined. To elucidate the role of the IL-6/gp130/Stat3 signaling axis in the cellular and molecular pathogenesis of emphysema, we employed a genetic complementation strategy using emphysematous gp130(F/F) mice displaying hyperactivation of endogenous Stat3 that were interbred with mice to impede Stat3 activity. Resected human lung tissue from patients with COPD and COPD-free individuals was also evaluated by immunohistochemistry. Genetic reduction of Stat3 hyperactivity in gp130(F/F):Stat3(-/+) mice prevented lung inflammation and excessive protease activity; however, emphysema still developed. In support of these findings, Stat3 activation levels in human lung tissue correlated with the extent of pulmonary inflammation but not airflow obstruction in COPD. Furthermore, COPD lung tissue displayed increased levels of IL-6 and apoptotic alveolar cells, supporting our previous observation that increased endogenous IL-6 expression in the lungs of gp130(F/F) mice contributes to emphysema by promoting alveolar cell apoptosis. Collectively, our data suggest that IL-6 promotes emphysema via upregulation of Stat3-independent apoptosis, whereas IL-6 induction of lung inflammation occurs via Stat3. We propose that while discrete targeting of Stat3 may alleviate pulmonary inflammation, global targeting of IL-6 potentially represents a therapeutically advantageous approach to combat COPD phenotypes where emphysema predominates.

Dual‐energy X‐ray absorptiometry is the method of choice to assess body composition in COPD

Background and objective:  Mortality and morbidity in COPD have been related to reduced FEV1 as well as indices of body composition. Different techniques used to evaluate body composition may vary in accuracy, particularly in conditions with altered fluid balance such as COPD. We hypothesized that direct measurement of fat‐free mass index (FFMI) by dual‐energy X‐ray absorptiometry (DEXA) would provide superior assessment of body composition in COPD.

Inosine-Mediated Modulation of RNA Sensing by Toll-Like Receptor 7 (TLR7) and TLR8

ABSTRACT RNA-specific adenosine deaminase (ADAR)-mediated adenosine-to-inosine (A-to-I) editing is a critical arm of the antiviral response. However, mechanistic insights into how A-to-I RNA editing affects viral infection are lacking. We posited that inosine incorporation into RNA facilitates sensing of nonself RNA by innate immune sensors and accordingly investigated the impact of inosine-modified RNA on Toll-like receptor 7 and 8 (TLR7/8) sensing. Inosine incorporation into synthetic single-stranded RNA (ssRNA) potentiated tumor necrosis factor alpha (TNF-α) or alpha interferon (IFN-α) production in human peripheral blood mononuclear cells (PBMCs) in a sequence-dependent manner, indicative of TLR7/8 recruitment. The effect of inosine incorporation on TLR7/8 sensing was restricted to immunostimulatory ssRNAs and was not seen with inosine-containing short double-stranded RNAs or with a deoxy-inosine-modified ssRNA. Inosine-mediated increase of self-secondary structure of an ssRNA resulted in potentiated IFN-α production in human PBMCs through TLR7 recruitment, as established through the use of a TLR7 antagonist and Tlr7-deficient cells. There was a correlation between hyperediting of influenza A viral ssRNA and its ability to stimulate TNF-α, independent of 5′-triphosphate residues, and involving Adar-1. Furthermore, A-to-I editing of viral ssRNA directly enhanced mouse Tlr7 sensing, when present in proportions reproducing biologically relevant levels of RNA editing. Thus, we demonstrate for the first time that inosine incorporation into immunostimulatory ssRNA can potentiate TLR7/8 activation. Our results suggest a novel function of A-to-I RNA editing, which is to facilitate TLR7/8 sensing of phagocytosed viral RNA.

Blockade of the IL-6 trans-signalling/STAT3 axis suppresses cachexia in Kras-induced lung adenocarcinoma

Lung cancer is the leading cause of cancer death worldwide, and is frequently associated with the devastating paraneoplastic syndrome of cachexia. The potent immunomodulatory cytokine interleukin (IL)-6 has been linked with the development of lung cancer as well as cachexia; however, the mechanisms by which IL-6 promotes muscle wasting in lung cancer cachexia are ill-defined. In this study, we report that the gp130F/F knock-in mouse model displaying hyperactivation of the latent transcription factor STAT3 via the common IL-6 cytokine family signalling receptor, gp130, develops cachexia during Kras-driven lung carcinogenesis. Specifically, exacerbated weight loss, early mortality and reduced muscle and adipose tissue mass were features of the gp130F/F:KrasG12D model, but not parental KrasG12D mice in which STAT3 was not hyperactivated. Gene expression profiling of muscle tissue in cachectic gp130F/F:KrasG12D mice revealed the upregulation of IL-6 and STAT3-target genes compared with KrasG12D muscle tissue. These cachectic features of gp130F/F:KrasG12D mice were abrogated upon the genetic normalization of STAT3 activation or ablation of IL-6 in gp130F/F:KrasG12D:Stat3−/+ or gp130F/F:KrasG12D:Il6−/− mice, respectively. Furthermore, protein levels of the soluble IL-6 receptor (sIL-6R), which is the central facilitator of IL-6 trans-signalling, were elevated in cachectic muscle from gp130F/F:KrasG12D mice, and the specific blockade of IL-6 trans-signalling, but not classical signalling, with an anti-IL-6R antibody ameliorated cachexia-related characteristics in gp130F/F:KrasG12D mice. Collectively, these preclinical findings identify trans-signalling via STAT3 as the signalling modality by which IL-6 promotes muscle wasting in lung cancer cachexia, and therefore support the clinical evaluation of the IL-6 trans-signalling/STAT3 axis as a therapeutic target in advanced lung cancer patients presenting with cachexia.

Differential involvement of gp130 signalling pathways in modulating tobacco carcinogen-induced lung tumourigenesis

Interleukin (IL)-6 family cytokines signal exclusively via the gp130 coreceptor, and are implicated in smoking-associated lung cancer, the most lethal cancer worldwide. However, the role of gp130 signalling pathways in transducing the carcinogenic effects of tobacco-related compounds is ill-defined. Here, we report that lung tumourigenesis induced by the potent tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (Nicotine-derived Nitrosamine Ketone; NNK) is suppressed in gp130F/F knock-in mice characterized by the contrasting gp130-dependant hypoactivation of extracellular signal-regulated kinase mitogen-activated protein kinase (ERK MAPK) and phosphatidylinositol 3-kinase/Akt, and hyperactivation of signal transducer and activator of transcription (STAT)3 signalling cascades. Specifically, in response to NNK, the absolute number and size of lung lesions in gp130F/F mice were significantly reduced compared with gp130+/+ littermate controls, and associated with lower cellular proliferation without any alteration to the level of apoptosis in gp130F/F lung tumours. At the molecular level, reduced activation of ERK MAPK, but not Akt, was observed in lung tumours of gp130F/F mice, and corresponded with impaired expression of several tumour suppressor genes (for example, Trp53, Tsc2). Notably, STAT3 was not activated in the lungs of gp130+/+ mice by NNK, and genetic normalization of STAT3 activation in gp130F/F:Stat3−/+ mice had no effect on NNK-induced tumourigenesis. The expression of tumour suppressor genes was reduced in tumours from current versus never-smoking lung cancer patients, and in vitro pharmacological inhibition of ERK MAPK signalling in human lung cancer cells abrogated NNK-induced downmodulation of tumour suppressor gene expression. Among IL-6 cytokine family members, IL-6 gene expression was specifically upregulated by NNK in vitro and in vivo, and inversely correlated with tumour suppressor gene expression. Collectively, our data reveal that a key molecular mechanism by which NNK promotes tumour cell proliferation during tobacco carcinogen-induced lung carcinogenesis is via upregulation of IL-6 and the preferential usage of gp130-dependant ERK MAPK signalling to downmodulate tumour suppressor gene expression.

Incidental Pulmonary Nodules Are Common on CT Coronary Angiogram and Have a Significant Cost Impact

BACKGROUND Computed tomography (CT) coronary angiogram (CTCA) is commonly used for diagnostic evaluation of low-moderate risk patients due to its excellent performance and cost-effectiveness. However, previous cost analyses have not factored in the burden of management of pulmonary nodules, which are a common occurrence. We sought to describe the frequency and characteristics of lung nodules on CTCA in an Australian tertiary hospital, and to assess cost impacts. METHODS Consecutive CTCAs performed in the calendar year 2012 were retrospectively identified from the imaging department database. Subjects were excluded if they were under the age of 35, had known malignancy or findings identified prior to CTCA. Patients were stratified on smoking history and nodule size. RESULTS Of the 2479 CTCAs included, full-field imaging revealed nodules in 358 patients (13.9%). The nodules were generally small (73% <6mm), multiple (63%) and in the lower lobe (83.4%). There was no significant difference when stratified for smoking, with 60% of nodules detected in never-smokers. A minimum of 445 subsequent scans was required for nodule surveillance, resulting in an additional overall cost of

In vivo evidence that RBM5 is a tumour suppressor in the lung

63.62 per CTCA. Limited-Field-of-View (L-FOV) would have identified only 22 nodules, with a cost of

Consensus minimum data set for lung cancer multidisciplinary teams: Results of a Delphi process: Consensus on lung cancer MDT data set

6.14 for every CTCA performed, a cost saving of