Strong toll-like receptor responses in cystic fibrosis patients are associated with higher lung function

Clinical implications of innate immune exhaustion in cystic fibrosis

Objectives

Lung disease progression in people with cystic fibrosis (pwCF) varies from one individual to another. Different immunological characteristics have been suggested to explain this variation, and we hypothesised that lung capacity may be associated with the innate immune response in pwCF. In an exploratory study, we aimed to investigate potential links between the innate immune response and lung function in pwCF using the standardised immune function assay TruCulture.

Methods

In a single-centre study with combined cross-sectional and longitudinal data before and after intravenous antibiotics, blood was sampled from Pseudomonas aeruginosa-infected pwCF. Whole blood was analysed by TruCulture to reveal the unstimulated and stimulated cytokine release. Tobit regressions and Spearman's correlations were used to estimate the associations between lung function and cytokine release.

Results

We included 52 pwCF in the cross-sectional study and 24 in the longitudinal study. In the cross-sectional study, we found that compared to a healthy population, the release of toll-like receptor (TLR)3, TLR4- and TLR7/8-stimulated interferon-γ, and interleukin (IL)-12p40 was reduced. Although TLR3-stimulated IL-1β and IL-6 release increased with lung function, overall, cytokine release did not correlate well with lung function. In the longitudinal study, the cytokine release was modified by antibiotic treatment, but the cytokine release before antibiotic treatment did not associate with changes in lung function after treatment.

Conclusion

The stimulated cytokine release could not predict lung function levels or changes in pwCF, but our data indicate that pwCF experience exhaustion in the innate immune response after years of chronic bacterial infection.

Synonymous mutations in TLR2 and TLR9 genes decrease COPD susceptibility in the Chinese Han population

INTRODUCTION

Previous studies have found associations between polymorphisms in some candidate genes and chronic obstructive pulmonary disease (COPD) risk. However, the association between TLR2 and TLR9 polymorphisms and COPD risk remains uncertain.

METHODS

Four variants (rs352140, rs3804099, rs3804100, and rs5743705) of the TLR2 and TLR9 genes in 540 COPD patients and 507 healthy controls were genotyped using the Agena MassARRAY system. Odds ratio (OR) and 95% confidence interval (CI) were calculated to assess the association of TLR2 and TLR9 polymorphisms with COPD risk by logistic regression analysis.

RESULTS

TLR9-rs352140, TLR2-rs3804100, and TLR2-rs5743705 were related to a lower risk of COPD among Chinese people and the significance still existed after Bonferroni correction. Additionally, rs3804099, rs3804100, and rs352140 were found to be associated with COPD development in different subgroups (males, age ≤ 68 years, smokers, BMI < 24 kg/m2, and acute exacerbation).

CONCLUSIONS

Our findings indicated that TLR9 and TLR2 polymorphisms had protective effects on the development of COPD among Chinese people.

The Impact of Highly Effective Modulator Therapy on Cystic Fibrosis Microbiology and Inflammation

Highly effective cystic fibrosis (CF) transmembrane conductance regulator (CFTR) modulator therapy (HEMT) corrects the underlying molecular defect causing CF disease. HEMT decreases symptom burden and improves clinical metrics and quality of life for most people with CF (PwCF) and eligible cftr mutations. Improvements in measures of pulmonary health suggest that restoration of function of defective CFTR anion channels by HEMT not only enhances airway mucociliary clearance, but also reduces chronic pulmonary infection and inflammation. This article reviews the evidence for how HEMT influences the dynamic and interdependent processes of infection and inflammation in the CF airway, and what questions remain unanswered.

Toll like Receptor signalling by Prevotella histicola activates alternative NF-κB signalling in Cystic Fibrosis bronchial epithelial cells compared to P. aeruginosa

Cystic Fibrosis (CF), caused by mutations affecting the CFTR gene, is characterised by viscid secretions in multiple organ systems. CF airways contain thick mucus, creating a gradient of hypoxia, which promotes the establishment of polymicrobial infection. Such inflammation predisposes to further infection, a self-perpetuating cycle in mediated by NF-κB. Anaerobic Gram-negative Prevotella spp. are found in sputum from healthy volunteers and CF patients and in CF lungs correlate with reduced levels of inflammation. Prevotella histicola (P. histicola) can suppress murine lung inflammation, however, no studies have examined the role of P. histicola in modulating infection and inflammation in the CF airways. We investigated innate immune signalling and NF-kB activation in CF epithelial cells CFBE41o- in response to clinical stains of P. histicola and Pseudomonas aeruginosa (P. aeruginosa). Toll-Like Receptor (TLR) expressing HEK-293 cells and siRNA assays for TLRs and IKKα were used to confirm signalling pathways. We show that P. histicola infection activated the alternative NF-kB signalling pathway in CF bronchial epithelial cells inducing HIF-1α protein. TLR5 signalling was responsible for the induction of the alternative NF-kB pathway through phosphorylation of IKKα. The induction of transcription factor HIF-1α was inversely associated with the induction of the alternative NF-kB pathway and knockdown of IKKα partially restored canonical NF-kB activation in response to P. histicola. This study demonstrates that different bacterial species in the respiratory microbiome can contribute differently to inflammation, either by activating inflammatory cascades (P. aeruginosa) or by muting the inflammatory response by modulating similar or related pathways (P. histicola). Further work is required to assess the complex interactions of the lung microbiome in response to mixed bacterial infections and their effects in people with CF.

CFTR Modulator Therapy Enhances Peripheral Blood Monocyte Contributions to Immune Responses in People With Cystic Fibrosis

Background

CFTR modulators decrease some etiologies of CF airway inflammation; however, data indicate that non-resolving airway infection and inflammation persist in individuals with CF and chronic bacterial infections. Thus, identification of therapies that diminish airway inflammation without allowing unrestrained bacterial growth remains a critical research goal. Novel strategies for combatting deleterious airway inflammation in the CFTR modulator era require better understanding of cellular contributions to chronic CF airway disease, and how inflammatory cells change after initiation of CFTR modulator therapy. Peripheral blood monocytes, which traffic to the CF airway, can develop both pro-inflammatory and inflammation-resolving phenotypes, represent intriguing cellular targets for focused therapies. This therapeutic approach, however, requires a more detailed knowledge of CF monocyte cellular programming and phenotypes.

Material and Methods

In order to characterize the inflammatory phenotype of CF monocytes, and how these cells change after initiation of CFTR modulator therapy, we studied adults (n=10) with CF, chronic airway infections, and the CFTR-R117H mutations before and 7 days after initiation of ivacaftor. Transcriptomes of freshly isolated blood monocytes were interrogated by RNA-sequencing (RNA-seq) followed by pathway-based analyses. Plasma concentrations of cytokines and chemokines were evaluated by multiplex ELISA.

Results

RNAseq identified approximately 50 monocyte genes for which basal expression was significantly changed in all 10 subjects after 7 days of ivacaftor. Of these, the majority were increased in expression post ivacaftor, including many genes traditionally associated with enhanced inflammation and immune responses. Pathway analyses confirmed that transcriptional programs were overwhelmingly up-regulated in monocytes after 7 days of ivacaftor, including biological modules associated with immunity, cell cycle, oxidative phosphorylation, and the unfolded protein response. Ivacaftor increased plasma concentrations of CXCL2, a neutrophil chemokine secreted by monocytes and macrophages, and CCL2, a monocyte chemokine.

Conclusions

Our results demonstrate that ivacaftor causes acute changes in blood monocyte transcriptional profiles and plasma chemokines, and suggest that increased monocyte inflammatory signals and changes in myeloid cell trafficking may contribute to changes in airway inflammation in people taking CFTR modulators. To our knowledge, this is the first report investigating the transcriptomic response of circulating blood monocytes in CF subjects treated with a CFTR modulator.