Oxidised IL-33 drives COPD epithelial pathogenesis via ST2-independent RAGE/EGFR signalling complex

BACKGROUND

Epithelial damage, repair and remodelling are critical features of chronic airway diseases including chronic obstructive pulmonary disease (COPD). Interleukin (IL)-33 released from damaged airway epithelia causes inflammation via its receptor, serum stimulation-2 (ST2). Oxidation of IL-33 to a non-ST2-binding form (IL-33ox) is thought to limit its activity. We investigated whether IL-33ox has functional activities that are independent of ST2 in the airway epithelium.

METHODS

In vitro epithelial damage assays and three-dimensional, air-liquid interface (ALI) cell culture models of healthy and COPD epithelia were used to elucidate the functional role of IL-33ox. Transcriptomic changes occurring in healthy ALI cultures treated with IL-33ox and COPD ALI cultures treated with an IL-33-neutralising antibody were assessed with bulk and single-cell RNA sequencing analysis.

RESULTS

We demonstrate that IL-33ox forms a complex with receptor for advanced glycation end products (RAGE) and epidermal growth factor receptor (EGFR) expressed on airway epithelium. Activation of this alternative, ST2-independent pathway impaired epithelial wound closure and induced airway epithelial remodelling in vitro. IL-33ox increased the proportion of mucus-producing cells and reduced epithelial defence functions, mimicking pathogenic traits of COPD. Neutralisation of the IL-33ox pathway reversed these deleterious traits in COPD epithelia. Gene signatures defining the pathogenic effects of IL-33ox were enriched in airway epithelia from patients with severe COPD.

CONCLUSIONS

Our study reveals for the first time that IL-33, RAGE and EGFR act together in an ST2-independent pathway in the airway epithelium and govern abnormal epithelial remodelling and muco-obstructive features in COPD.

The IL-33:ST2 axis is unlikely to play a central fibrogenic role in idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a devastating interstitial lung disease (ILD) with limited treatment options. Interleukin-33 (IL-33) is proposed to play a role in the development of IPF however the exclusive use of prophylactic dosing regimens means that the therapeutic benefit of targeting this cytokine in IPF is unclear.

METHODS

IL-33 expression was assessed in ILD lung sections and human lung fibroblasts (HLFs) by immunohistochemistry and gene/protein expression and responses of HLFs to IL-33 stimulation measured by qPCR. In vivo, the fibrotic potential of IL-33:ST2 signalling was assessed using a murine model of bleomycin (BLM)-induced pulmonary fibrosis and therapeutic dosing with an ST2-Fc fusion protein. Lung and bronchoalveolar lavage fluid were collected for measurement of inflammatory and fibrotic endpoints. Human precision-cut lung slices (PCLS) were stimulated with transforming growth factor-β (TGFβ) or IL-33 and fibrotic readouts assessed.

RESULTS

IL-33 was expressed by fibrotic fibroblasts in situ and was increased by TGFβ treatment in vitro. IL-33 treatment of HLFs did not induce IL6, CXCL8, ACTA2 and COL1A1 mRNA expression with these cells found to lack the IL-33 receptor ST2. Similarly, IL-33 stimulation had no effect on ACTA2, COL1A1, FN1 and fibronectin expression by PCLS. Despite having effects on inflammation suggestive of target engagement, therapeutic dosing with the ST2-Fc fusion protein failed to reduce BLM-induced fibrosis measured by hydroxyproline content or Ashcroft score.

CONCLUSIONS

Together these findings suggest the IL-33:ST2 axis does not play a central fibrogenic role in the lungs with therapeutic blockade of this pathway unlikely to surpass the current standard of care for IPF.

Differential remodeling in small and large murine airways revealed by novel whole lung airway analysis

Airway remodeling occurs in chronic asthma leading to increased airway smooth muscle (ASM) mass and extracellular matrix (ECM) deposition. Although extensively studied in murine airways, studies report only selected larger airways at one time-point meaning the spatial distribution and resolution of remodeling are poorly understood. Here we use a new method allowing comprehensive assessment of the spatial and temporal changes in ASM, ECM, and epithelium in large numbers of murine airways after allergen challenge. Using image processing to analyze 20-50 airways per mouse from a whole lung section revealed increases in ASM and ECM after allergen challenge were greater in small and large rather than intermediate airways. ASM predominantly accumulated adjacent to the basement membrane, whereas ECM was distributed across the airway wall. Epithelial hyperplasia was most marked in small and intermediate airways. After challenge, ASM changes resolved over 7 days, whereas ECM and epithelial changes persisted. The new method suggests large and small airways remodel differently, and the long-term consequences of airway inflammation may depend more on ECM and epithelial changes than ASM. The improved quantity and quality of unbiased data provided by the method reveals important spatial differences in remodeling and could set new analysis standards for murine asthma models.

Clinical experience and choice of drug therapy for human immunodeficiency virus disease

To determine if providers experienced in the management of human immunodeficiency virus (HIV) disease preferred different treatment regimens than providers with less experience, we analyzed data from a national survey of primary care providers' preferred regimens for the management of 30 HIV-related medical conditions. We mailed questionnaires to 999 correct addresses of providers in > 20 cities in the United States in May 1996. We received 524 responses (response rate, 52%). We found a statistically significant association between the number of HIV-infected patients cared for by the provider and the likelihood that the provider would report prescribing highly active antiretroviral therapy and multidrug combinations for treatment of opportunistic infections. Providers with few HIV-infected patients were substantially less likely to report using new therapeutic regimens or new diagnostic tools. We concluded that the preferred regimens of experienced providers are more likely to be consistent with the latest information on treatment for HIV disease than are those of less experienced providers.