The Use of Inhaled Corticosteroids for Patients with COPD Who Continue to Smoke Cigarettes: An Evaluation of Current Practice

The use of inhaled corticosteroids (ICS) in combination with inhaled bronchodilators for patients with chronic obstructive pulmonary disease (COPD) is a common practice in primary care settings. However, ICS-containing therapies may be less effective in patients with COPD compared with asthma, and in individuals with COPD who continue to smoke cigarettes. Preclinical studies suggest that inflammation in COPD is very different from in asthma. Glucocorticoid receptor functioning and other innate anti-inflammatory mechanisms are altered in cells exposed to cigarette smoke. COPD may be relatively insensitive to ICS, especially in individuals who continue to smoke. ICS-containing therapies in patients with asthma who continue to smoke may also be less effective compared with patients who do not smoke. ICS-containing therapies may be inappropriately used in some patients with COPD, and their long-term use is associated with an increased risk for side effects, including pneumonia and bone fractures in some patients. Treatment for patients with COPD should be carefully evaluated, and anti-inflammatory/bronchodilatory strategies should be chosen based on individual patient characteristics and recommendations in current guidelines.

Erythromycin reverses cigarette smoke extract-induced corticosteroid insensitivity by inhibition of the JNK/c-Jun pathway

Corticosteroid insensitivity is a feature of airway inflammation in chronic obstructive pulmonary disease (COPD). Erythromycin exhibits anti-inflammatory activity in COPD, but the concrete mechanism is still unclear. This study aimed to investigate the effects of erythromycin on corticosteroid sensitivity in peripheral blood mononuclear cells (PBMCs) and U937 cells (a human monocytic cell line). PBMCs were collected from non-smokers, healthy smoker volunteers, and COPD subjects. U937 cells were incubated with or without erythromycin and stimulated with TNF-α in the presence or absence of cigarette smoke extract (CSE). The dexamethasone (Dex) concentration required to achieve 50% inhibition of TNF-α-induced interleukin (IL)-8 production was determined and the mitogen-activated protein kinase (MAPK)/Activator protein-1 (AP-1) pathway was also evaluated. Erythromycin improved corticosteroid sensitivity in PBMCs obtained from COPD patients and CSE-treated U937 cells. This improvement in corticosteroid sensitivity was associated with reduced c-Jun expression, which resulted from the inhibition of P38 Mitogen-activated protein kinase (P38MAPK), extracellular signal-regulated protein kinase (ERK)1/2, and c-Jun N-terminal kinase (JNK) phosphorylation. Erythromycin had no effects on the phosphorylated and total protein expression levels of P38MAPK and ERK; however, it induced inhibition of the phosphorylated and total protein expression levels of JNK. This study provides evidence that erythromycin restores corticosteroid sensitivity in PBMCs and U937 cells. JNK inhibition by erythromycin restores corticosteroid sensitivity via the inhibition of c-Jun expression. Thus, JNK/c-Jun is a potential novel therapeutic target for COPD.

P38 MAPK and glucocorticoid receptor crosstalk in bronchial epithelial cells

Abstract

p38 MAPK inhibition may have additive and synergistic anti-inflammatory effects when used with corticosteroids. We investigated crosstalk between p38 MAPK inhibitors and corticosteroids in bronchial epithelial cells to investigate synergistic effects on cytokine production and the molecular mechanisms involved. Effects of the p38 MAPK inhibitor BIRB-796 and dexamethasone alone and in combination on LPS, polyI:C or TNFα -induced IL-6, CXCL8 and RANTES were assessed in 16HBEs (human epithelial cell line) and on TNFα-induced IL-6 and CXCL8 in primary human epithelial cells from asthma patients and healthy controls. 16HBEs were used to assess effects of BIRB-796 alone and in combination with dexamethasone on glucocorticoid receptor (GR) activity by reporter gene assay, expression of GR target genes and nuclear localisation using Western blot. The effects of BIRB-796 on TNFα stimulated phosphorylation of p38 MAPK and GR at serine (S) 226 by Western blot. Epithelial levels of phosphorylated p38 MAPK and GR S226 were determined by immunohistochemistry in bronchial biopsies from asthma patients and healthy controls. BIRB-796 in combination with dexamethasone increased inhibition of cytokine production in a synergistic manner. Combination treatment significantly increased GR nuclear localisation compared to dexamethasone alone. BIRB-796 inhibited TNFα-induced p38 MAPK and GR S226 phosphorylation. Phosphorylated GR S226 and p38 MAPK levels were increased in bronchial epithelium of more severe asthma patients. Molecular crosstalk exists between p38 MAPK activation and GR function in human bronchial epithelial cells, which alters GR activity. Combining a p38 MAPK inhibitor and a corticosteroid may demonstrate therapeutic potential in severe asthma.

Key messages

• Combination of corticosteroid and p38 inhibitor in human bronchial epithelial cells

• Combination increased cytokine inhibition synergistically and nuclear GR

• p38 MAPK inhibition reduced TNFα-induced phosphorylation of GR at S226 but not S211

• Phosphorylated GRS226 and p38 is increased in bronchial epithelium in severe asthma

• Combining a p38 inhibitor and a corticosteroid may be effective in asthma treatment

Electronic supplementary material

The online version of this article (10.1007/s00109-020-01873-3) contains supplementary material, which is available to authorized users.

LncRNA-CASC7 enhances corticosteroid sensitivity via inhibiting the PI3K/AKT signaling pathway by targeting miR-21 in severe asthma

BACKGROUND

Asthma, a common chronic inflammatory disease, is treated with corticosteroid in most cases, but corticosteroid resistance in severe asthma patients seriously impairs the therapeutic effects. LncRNA-CASC7 inhibits cell proliferation and enhances drug sensitivity, but the molecular mechanisms of corticosteroid resistance in severe asthma are still unknown.

METHODS

Airway smooth muscle cells (ASMCs) from healthy and severe asthmatic subjects were used in this study. The expression of CASC7 and miR-21 were modified by transfection with the pcDNA3.1-CASC7, miR-21 mimics and inhibitor. MTT assay was conducted to measure cell proliferation. ELISA assay was used to determine the secretion of CCL5, CCL11 and IL-6. The phosphorylation of glucocorticoid receptor (GR) and the PI3K/AKT signaling were assessed by western blotting assays. qRT-PCR was used to analyze the expression of CASC7, miR-21 and PTEN. Dual-luciferase reporter assay was used to assess the interaction among CASC7, miR-21 and PTEN.

RESULTS

Compared with AMSCs from severe asthma patients, dexamethasone inhibited cytokines (CCL5, CCL11 and IL-6) and promoted the phosphorylation of GR more significantly in normal AMSCs. CASC7 expression was suppressed while miR-21 expression and AKT activity were promoted in ASMCs from severe asthma patients. CASC7 promoted PTEN expression via directly inhibiting miR-21 expression. Overexpression of CASC7 suppressed the PI3K/AKT signaling pathway and promoted the inhibition effects of dexamethasone on cell proliferation and cytokines secretion via targeting miR-21.

CONCLUSION

CASC7 increased corticosteroid sensitivity by inhibiting the PI3K/AKT signaling pathway via targeting miR-21, which provided a promising potential target for designing novel therapeutic strategy for severe asthma.

Increased serum amyloid A in nasal polyps is associated with systemic corticosteroid insensitivity in patients with chronic rhinosinusitis with nasal polyps: a pilot study

BACKGROUND

Serum amyloid A (SAA) was involved in the pathogenesis of glucocorticoid resistance in lung diseases. However, their association with systemic corticosteroid insensitivity in chronic rhinosinusitis with nasal polyps (CRSwNP) patients remains to be assessed.

METHODS

This study enrolled 32 CRSwNP patients to evaluate the association between SAA expression in NP and corticosteroid insensitivity, and the value of polyp SAA level for predicting the response to oral corticosteroids in CRSwNP patients. All patients were given a course of oral prednisone (30 mg daily for 2 weeks) and subdivided into glucocorticoid(GC)-sensitive and -insensitive subgroup according to the change in polyp size scores. The polyp specimens were obtained before and after corticosteroid treatment. SAA levels in polyp tissues were evaluated by enzyme-linked immunosorbent assay and quantitative reverse transcription polymerase chain reaction. Regression analysis was performed to analyze the association between SAA protein levels and corticosteroid insensitivity.

RESULTS

13/32 (40.62%) CRSwNP patients were insensitive to the oral corticosteroid therapy. SAA mRNA and protein levels were significantly increased in GC-insensitive NP compared to those in GC-sensitive NP. Tissue SAA protein levels were positively correlated with tissue neutrophil numbers. Regression analysis revealed tissue SAA levels were significantly correlated with corticosteroid insensitivity (P < 0.01). ROC curves indicated that the area under the curve was 0.87. When the polyp SAA protein level was 122.2 ng/ml or higher, the sensitivity and specificity were 76.92 and 73.68%, respectively.

CONCLUSIONS

Our findings suggest that increased SAA in NP is associated with reduced response to oral corticosteroids in CRSwNP. SAA levels in NP may have potential value in predicting corticosteroid insensitivity in CRSwNP patients.

TLR2 ligation induces corticosteroid insensitivity in A549 lung epithelial cells: Anti-inflammatory impact of PP2A activators

Corticosteroids are effective anti-inflammatory therapies widely utilized in chronic respiratory diseases. But these medicines can lose their efficacy during respiratory infection resulting in disease exacerbation. Further in vitro research is required to understand how infection worsens lung function control in order to advance therapeutic options to treat infectious exacerbation in the future. In this study, we utilize a cellular model of bacterial exacerbation where we pretreat A549 lung epithelial cells with the synthetic bacterial lipoprotein Pam3CSK4 (a TLR2 ligand) to mimic bacterial infection and tumor necrosis factor α (TNFα) to simulate inflammation. Under these conditions, Pam3CSK4 induces corticosteroid insensitivity; demonstrated by substantially reduced ability of the corticosteroid dexamethasone to repress TNFα-induced interleukin 6 secretion. We then explored the molecular mechanism responsible and found that corticosteroid insensitivity induced by bacterial mimics was not due to altered translocation of the glucocorticoid receptor into the nucleus, nor an impact on the NF-κB pathway. Moreover, Pam3CSK4 did not affect corticosteroid-induced upregulation of anti-inflammatory MAPK deactivating phosphatase-MKP-1. However, Pam3CSK4 can induce oxidative stress and we show that a proportion of the MKP-1 produced in response to corticosteroid in the context of TLR2 ligation was rendered inactive by oxidation. Thus to combat inflammation in the context of bacterial exacerbation we sought to discover effective strategies that bypassed this road-block. We show for the first time that known (FTY720) and novel (theophylline) activators of the phosphatase PP2A can serve as non-steroidal anti-inflammatory alternatives and/or corticosteroid-sparing approaches in respiratory inflammation where corticosteroid insensitivity exists.

Protein tyrosine phosphatase PTP-RR regulates corticosteroid sensitivity

Background

We have recently reported that protein phosphate 2A (PP2A) inactivation resulted in increased phosphorylation of the mitogen-activated protein kinase (MAPK) c-Jun N-terminal kinase 1 (JNK1) and glucocorticoid receptors (GR) at Ser²²⁶, thereby reducing GR nuclear translocation and causing corticosteroid insensitivity in severe asthmatics. Protein tyrosine phosphatases (PTPs) are also known to be critically involved in the regulation of MAPKs, such as JNK and therefore potentially associated with GR function. The aim of study was to elucidate the involvement of MAPK-PTPs (PTP-RR, PTP-N5 and PTP-N7), which can dephosphorylate MAPKs, in the regulation of corticosteroid sensitivity.

Methods

Corticosteroid sensitivity, GR nuclear translocation, phosphorylation levels of GR-Ser²²⁶, JNK1 and PP2A catalytic subunit (PP2A_C)-Tyr³⁰⁷ and protein expression levels and activities of PTP-RR and PP2A_C were evaluated in U937 cells and/or peripheral blood mononuclear cells (PBMCs). Knock-down effects of MAPK-PTPs using siRNA were also evaluated.

Results

Knock-down of PTP-RR, but not of PTP-N5 or PTP-N7 impaired corticosteroid sensitivity, induced GR-Ser²²⁶ phosphorylation and reduced GR nuclear translocation. Under IL-2/IL-4-induced corticosteroid insensitivity, PTP-RR expression, activity and associations with JNK1 and GR were reduced but PTP-RR activity was restored by formoterol. Also in PBMCs from severe asthmatic patients, PTP-RR and JNK1 expression were reduced and GR-Ser²²⁶ phosphorylation increased. Furthermore, PTP-RR was associated with PP2A. PTP-RR reduction enhanced PP2A_C-Tyr³⁰⁷ phosphorylation leading to impairment of PP2A expression and activity.

Conclusions

We demonstrated that with corticosteroid insensitivity PTP-RR fails to reduce phosphorylation of JNK1 and GR-Ser²²⁶, resulting in down-regulation of GR nuclear translocation. Reduced PTP-RR may represent a novel cause of corticosteroid insensitivity in severe asthmatics.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-016-0349-0) contains supplementary material, which is available to authorized users.