Longitudinal changes in airway hyperresponsiveness and COPD mortality

Endoplasmic reticulum stress in airway hyperresponsiveness

Airway hyperresponsiveness(AHR) is a major clinical phenomenon in lung diseases (asthma, COPD and pulmonary fibrosis) and not only a high-risk factor for perioperative airway spasm leading to hypoxaemia, haemodynamic instability and even "silent lung", but also a potential risk for increased mortality from underlying diseases (e.g. asthma, COPD). Airway reactivity is closely linked to airway inflammation, remodelling and increased mucus secretion, and endoplasmic reticulum stress is an important mechanism for the development of these pathologies. This review, therefore, focuses on the effects of endoplasmic reticulum stress on the immune cells involved in airway hyperreactivity (epithelial cells, dendritic cells, eosinophils and neutrophils) in inflammation and mucus & sputum secretion; and on the differentiation and remodelling of airway smooth muscle cells and epithelial cells. The aim is to clarify the mechanisms associated with endoplasmic reticulum stress in airway hyperresponsiveness and to find new ideas and methods for the prevention of airway hyperresponsiveness in the perioperative period.

[Chronic obstructive pulmonary disease: the right treatment for the right patient]

In den vergangenen Jahren wurden auf dem Gebiet der chronisch-obstruktiven Lungenerkrankung (COPD) große Therapiestudien publiziert, die 2020 um mehrere Post-hoc-Analysen ergänzt wurden. Die neuen Erkenntnisse flossen in das Update des Global-Initiative-for-Chronic-Obstructive-Lung-Disease(GOLD)-Report 2021 ein. Im vorliegenden Beitrag werden die aktualisierten Grundlagen und Empfehlungen zur Therapie der COPD beschrieben. Dabei wird auf die Indikationen von inhalativen Kortikosteroiden (ICS), lang wirksamen Muskarinantagonisten (LAMA) und/oder lang wirksamen β‑Mimetika (LABA) eingegangen. Die Therapie der COPD wird der des Asthma bronchiale gegenübergestellt. Diskutiert wird auch, wie sich eine gleichzeitig bestehende Asthmakomponente auf die Behandlungsstrategie bei COPD auswirkt. Ein Schwerpunkt des Beitrags liegt auf der Triple-Therapie mit LAMA, LABA und ICS. In diesem Zusammenhang werden die Studienlage und die Indikationen beschrieben. Die Bronchodilatation bleibt weiterhin die Grundlage der COPD-Therapie. Für Patienten mit gehäuften Exazerbationen bedeutet eine Triple-Therapie mit LAMA + LABA + ICS einen Mortalitätsvorteil. Weitere Analysen oder Studien sollen klären, ob dieser Effekt für spezifische Subgruppen stärker ausgeprägt ist.

RAGE and TLR4 differentially regulate airway hyperresponsiveness: Implications for COPD

BACKGROUND

The receptor for advanced glycation end products (RAGE) and Toll-like receptor 4 (TLR4) is implicated in COPD. Although these receptors share common ligands and signalling pathways, it is not known whether they act in concert to drive pathological processes in COPD. We examined the impact of RAGE and/or TLR4 gene deficiency in a mouse model of COPD and also determined whether expression of these receptors correlates with airway neutrophilia and airway hyperresponsiveness (AHR) in COPD patients.

METHODS

We measured airway inflammation and AHR in wild-type, RAGE^-/- , TLR4^-/- and TLR4^-/- RAGE^-/- mice following acute exposure to cigarette smoke (CS). We also examined the impact of smoking status on AGER (encodes RAGE) and TLR4 bronchial gene expression in patients with and without COPD. Finally, we determined whether expression of these receptors correlates with airway neutrophilia and AHR in COPD patients.

RESULTS

RAGE^-/- mice were protected against CS-induced neutrophilia and AHR. In contrast, TLR4^-/- mice were not protected against CS-induced neutrophilia and had more severe CS-induced AHR. TLR4^-/- RAGE^-/- mice were not protected against CS-induced neutrophilia but were partially protected against CS-induced mediator release and AHR. Current smoking was associated with significantly lower AGER and TLR4 expression irrespective of COPD status, possibly reflecting negative feedback regulation. However, consistent with preclinical findings, AGER expression correlated with higher sputum neutrophil counts and more severe AHR in COPD patients. TLR4 expression did not correlate with neutrophilic inflammation or AHR.

CONCLUSIONS

Inhibition of RAGE but not TLR4 signalling may protect against airway neutrophilia and AHR in COPD.