Lower sensitivity of nasal polyp fibroblasts to glucocorticoid anti-proliferative effects

Lack of additive benefit of oral steroids on short-term postoperative outcomes in nasal polyposis

OBJECTIVES

There is a lack of evidence concerning the efficacy of oral corticosteroids (OCS) as a postoperative treatment for patients with chronic rhinosinusitis with nasal polyps (CRSwNP). The objective of our study was to determine the short-term additive benefit of postoperative OCS in CRSwNP patients.

METHODS

We prospectively randomized CRSwNP patients who were treated by endoscopic sinus surgery. All patients were resistant to maximum medical treatment according to European position paper on rhinosinusitis and nasal polyps 2012 guidelines. Treatment group received postoperative OCS in descending doses plus nasal douching over a period of 4 weeks, whereas the control group received only nasal douching. The efficacy of OCS was determined by a total 5 item symptoms score (T5SS), polyp size score, Barcelona Smell Test 24 and Medical Outcome Study Short Form-36 questionnaire for quality of life (QoL).

RESULTS

Of the 70 enrolled patients, 35 were in the treatment group and 35 in the control group. After 4 weeks of follow-up, patients from both groups improved in T5SS, QoL, endoscopic findings (except for crusts that increased in both) and sense of smell, without significant differences between OCS and control groups.

CONCLUSION

Postoperative OCS as an add-on treatment for CRSwNP patients does not improve sinonasal and QoL outcomes; thus, they should not be routinely recommended.

LEVEL OF EVIDENCE

Ib Laryngoscope, 2019.

Glucocorticoid receptor isoform expression in peripheral blood mononuclear leukocytes of patients with chronic rhinosinusitis

BACKGROUND

In several inflammatory disorders, altered peripheral blood mononuclear leukocyte (PBML) glucocorticoid (GC) receptor isoform expression has been associated with GC resistance and disease severity. However, it is unclear if PBML GC receptor isoforms are expressed differentially and are associated with worsened disease severity in chronic rhinosinusitis (CRS).

METHODS

PBMLs were isolated from control (n = 8), CRS without nasal polyps (CRSsNP) (n = 8), atopic CRS with nasal polyps (CRSwNP) (n = 8), non-atopic CRSwNP (n = 8), and allergic fungal rhinosinusitis (AFRS) (n = 8) patients. Demographics, atopic status, asthmatic status, 22-item Sino-Nasal Outcome Test (SNOT-22) scores, Lund-Kennedy nasal endoscopy scores, Lund-Mackay sinus computed tomography (CT) scores, Kennedy Osteitis scores, and GC utilization 6 months postoperatively were collected. Intracellular immunostaining was then performed for functional GC receptor α (GCRα) and nonfunctional GC receptor β (GCRβ), followed by flow cytometry analysis of geometric mean fluorescent intensity (MFI) and the percentage of cells expressing each GC receptor isoform.

RESULTS

Compared to controls, each CRS subtype had decreased PBML GCRα and GCRα:GCRβ MFI expression, but no difference in GCRβ expression. Decreasing PBML GCRα in AFRS was associated with increasing Lund-Mackay sinus CT scores (r = -0.880, p =0.004). No significant associations were found between GC receptor isoform expression and other clinical measures.

CONCLUSION

CRS patients have reduced functional PBML GCRα expression and decreased GCRα:GCRβ compared to controls. Reductions in GCRα in AFRS are associated with worsening Lund-Mackay sinus CT scores. The clinical implications of decreased functional GC receptor expression merits further investigation.

Effect of lipopolysaccharide on glucocorticoid receptor function in control nasal mucosa fibroblasts and in fibroblasts from patients with chronic rhinosinusitis with nasal polyps and asthma

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a chronic inflammatory disease of the upper airways frequently associated with asthma. Bacterial infection is a feature of CRSwNP that can aggravate the disease and the response to glucocorticoid treatment.

OBJECTIVE

We examined whether the bacterial product lipopolysaccharide (LPS) reduces glucocorticoid receptor (GR) function in control nasal mucosa (NM) fibroblasts and in nasal polyp (NP) fibroblasts from patients with CRSwNP and asthma.

METHODS

NP (n = 12) and NM fibroblasts (n = 10) were in vitro pre-incubated with LPS (24 hours) prior to the addition of dexamethasone. Cytokine/chemokine secretion was measured by ELISA and Cytometric Bead Array. GRα, GRβ, mitogen-activated protein-kinase phosphatase-1 (MKP-1) and glucocorticoid-induced leucine zipper (GILZ) expression was measured by RT-PCR and immunoblotting, GRα nuclear translocation by immunocytochemistry, and GRβ localization by immunoblotting. The role of MKP-1 and GILZ on dexamethasone-mediated cytokine inhibition was analyzed by small interfering RNA silencing.

RESULTS

Pre-incubation of nasal fibroblasts with LPS enhanced the secretion of IL-6, CXCL8, RANTES, and GM-CSF induced by FBS. FBS-induced CXCL8 secretion was higher in NP than in NM fibroblasts. LPS effects on IL-6 and CXCL8 were mediated via activation of p38α/β MAPK and IKK/NF-κB pathways. Additionally, LPS pre-incubation: 1) reduced dexamethasone's capacity to inhibit FBS-induced IL-6, CXCL8 and RANTES, 2) reduced dexamethasone-induced GRα nuclear translocation (only in NM fibroblasts), 3) did not alter GRα/GRβ expression, 4) decreased GILZ expression, and 5) did not affect dexamethasone's capacity to induce MKP-1 and GILZ expression. MKP-1 knockdown reduced dexamethasone's capacity to suppress FBS-induced CXCL8 release.

CONCLUSION

The bacterial product LPS negatively affects GR function in control NM and NP fibroblasts by interfering with the capacity of the activated receptor to inhibit the production of pro-inflammatory mediators. This study contributes to the understanding of how bacterial infection of the upper airways may limit the efficacy of glucocorticoid treatment.

Role of medical therapy in the management of nasal polyps

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a chronic inflammatory disease of the nasal and paranasal sinus mucosa that, despite differing hypotheses regarding its cause, remains poorly understood. Major symptoms are nasal congestion or blockage, loss of smell, rhinorrhea, postnasal drip, and facial pain or pressure. Among the objectives of CRSwNP management are to eradicate nasal polyps from nasal and sinusal cavities, eliminate symptoms, and prevent recurrences. Corticosteroids are the mainstay of treatment and are the most effective drugs for treating CRSwNP. Other potential treatments are nasal saline irrigation and antihistamines (in allergic conditions). Endoscopic sinus surgery is recommended when medical treatment fails. After surgery, medical treatment, including nasal and oral corticosteroids, is recommended.

Proteasome inhibition reduces proliferation, collagen expression, and inflammatory cytokine production in nasal mucosa and polyp fibroblasts

Proteasome inhibitors, used in cancer treatment for their proapoptotic effects, have anti-inflammatory and antifibrotic effects on animal models of various inflammatory and fibrotic diseases. Their effects in cells from patients affected by either inflammatory or fibrotic diseases have been poorly investigated. Nasal polyposis is a chronic inflammatory disease of the sinus mucosa characterized by tissue inflammation and remodeling. We tested the hypothesis that proteasome inhibition of nasal polyp fibroblasts might reduce their proliferation and inflammatory and fibrotic response. Accordingly, we investigated the effect of the proteasome inhibitor Z-Leu-Leu-Leu-B(OH)(2) (MG262) on cell viability and proliferation and on the production of collagen and inflammatory cytokines in nasal polyp and nasal mucosa fibroblasts obtained from surgery specimens. MG262 reduced the viability of nasal mucosa and polyp fibroblasts concentration- and time-dependently, with marked effects after 48 h of treatment. The proteasome inhibitor bortezomib provoked a similar effect. MG262-induced cell death involved loss of mitochondrial membrane potential, caspase-3 and poly(ADP-ribose) polymerase activation, induction of c-Jun phosphorylation, and mitogen-activated protein kinase phosphatase-1 expression. Low concentrations of MG262 provoked growth arrest, inhibited DNA replication and retinoblastoma phosphorylation, and increased expression of the cell cycle inhibitors p21 and p27. MG262 concentration-dependently inhibited basal and transforming growth factor-β-induced collagen mRNA expression and interleukin (IL)-1β-induced production of IL-6, IL-8, monocyte chemoattractant protein-1, regulated on activation normal T cell expressed and secreted, and granulocyte/macrophage colony-stimulating factor in both fibroblast types. MG262 inhibited IL-1β/tumor necrosis factor-α-induced activation of nuclear factor-κB. We conclude that noncytotoxic treatment with MG262 reduces the proliferative, fibrotic, and inflammatory response of nasal fibroblasts, whereas high MG262 concentrations induce apoptosis.

Dexamethasone and salbutamol stimulate human lung fibroblast proliferation

BACKGROUND

Asthma is characterized by bronchial hyperreactivity and airway remodeling. Subepithelial fibrosis, a feature of remodeling, is accompanied by activation of fibroblasts to myofibroblasts, with excessive proliferation and increased collagen, extracellular matrix protein, and profibrogenic cytokine production. Mast cells are important in the development of asthma and its fibrotic changes.

OBJECTIVE

In this study, we aimed to investigate the direct effect of the drugs most frequently used in asthma, that is, glucocorticosteroids (dexamethasone) and shortacting β(2)-agonists (salbutamol), on human lung fibroblast proliferation when unstimulated or activated by mast cells or eotaxin.

METHODS

Subconfluent human fetal lung or bronchial fibroblasts were incubated with different concentrations of the drugs (24 h) 6 activators, and [(3)H]-Thymidine was added (24 h) to measure their proliferation. IL-6 production in the supernatants of confluent monolayers cultured in the presence of the drugs or forskolin (24 h) was analyzed by enzyme-linked immunosorbent assay.

RESULTS

Both drugs alone and in the presence of the activators enhanced fibroblast proliferation in a seemingly synergistic way for both fetal and bronchial fibroblasts. Dexamethasone was found to decrease IL-6 production, while salbutamol increased it.

CONCLUSIONS

These observations if corroborated by in vivo data may possibly account for the deleterious effect of long-term therapy with β(2)-bronchodilators and inhaled glucocorticosteroids on the natural history of asthma.

Dexamethasone and Salbutamol Stimulate Human Lung Fibroblast Proliferation

Background

Asthma is characterized by bronchial hyperreactivity and airway remodeling. Subepithelial fibrosis, a feature of remodeling, is accompanied by activation of fibroblasts to myofibroblasts, with excessive proliferation and increased collagen, extracellular matrix protein, and profibrogenic cytokine production. Mast cells are important in the development of asthma and its fibrotic changes.

Objective

In this study, we aimed to investigate the direct effect of the drugs most frequently used in asthma, that is, glucocorticosteroids (dexamethasone) and shortacting β₂-agonists (salbutamol), on human lung fibroblast proliferation when unstimulated or activated by mast cells or eotaxin.

Methods

Subconfluent human fetal lung or bronchial fibroblasts were incubated with different concentrations of the drugs (24 h) 6 activators, and [³H]-Thymidine was added (24 h) to measure their proliferation. IL-6 production in the supernatants of confluent monolayers cultured in the presence of the drugs or forskolin (24 h) was analyzed by enzyme-linked immunosorbent assay.

Results

Both drugs alone and in the presence of the activators enhanced fibroblast proliferation in a seemingly synergistic way for both fetal and bronchial fibroblasts. Dexamethasone was found to decrease IL-6 production, while salbutamol increased it.

Conclusions

These observations if corroborated by in vivo data may possibly account for the deleterious effect of long-term therapy with β₂-bronchodilators and inhaled glucocorticosteroids on the natural history of asthma.