Involvement of mitogen-activated protein kinases and nuclear factor kappa B pathways in signaling COX-2 expression in chronic rhinosinusitis

The cyclooxygenase-2 upregulation mediates production of PGE2 autacoid to positively regulate interleukin-6 secretion in chronic rhinosinusitis with nasal polyps and polyp-derived fibroblasts

Chronic rhinosinusitis (CRS) can be traditionally classified as CRSwNP [with nasal polyps (NPs)] and CRSsNP (without NPs) based on the clinical phenotypes but recently suggested to be classified by the endotypes. We have identified overexpression of the cyclooxygenase-2 (COX-2) gene in NP tissues of Taiwanese CRSwNP patients. Therefore, in this study, we sought to investigate its protein expression/location/distribution in NP specimens and explore its roles in nasal polyposis. The COX-2 protein and mRNA expression was found higher in NPs than that in the control and CRSsNP patients' nasal tissues, mainly located at the epithelium and subepithelial stroma. Consistently, the CRS-related peptidoglycan (PGN) and bradykinin provoked COX-2 mRNA and protein upregulation in the human NP-derived fibroblasts and caused PGE2, thromboxane A2 (TXA2), and interleukin (IL-6) secretion in culture medium. Further analysis revealed that the PI3K/Akt activation and COX-2 induction were necessarily required for PGN-induced IL-6 production/secretion and the induced PGE2, but not TXA2, was speculated to affect IL-6 protein trafficking and production. Finally, the IL-6 increase observed in vitro could also be detected in NP tissues. Collectively, we demonstrated here that COX-2 protein and IL-6 are overexpressed in human NP tissues. In response to PGN challenge, the PI3K/Akt activation and COX-2-mediated PGE2 autacoid correlates with extracellular IL-6 protein trafficking/production in NP-derived fibroblasts, which can additionally contribute to the production of Th17-related cytokines such as IL-17 and TNF-α. This study also suggests COX-2 as a special biomarker for CRSwNP endotyping and may highlight the importance of COX-2 inhibitors in treating CRSwNP.

Allergic Aspergillus Rhinosinusitis

Allergic fungal rhinosinusitis (AFRS) is a unique variety of chronic polypoid rhinosinusitis usually in atopic individuals, characterized by presence of eosinophilic mucin and fungal hyphae in paranasal sinuses without invasion into surrounding mucosa. It has emerged as an important disease involving a large population across the world with geographic variation in incidence and epidemiology. The disease is surrounded by controversies regarding its definition and etiopathogenesis. A working group on "Fungal Sinusitis" under the International Society for Human and Animal Mycology (ISHAM) addressed some of those issues, but many questions remain unanswered. The descriptions of "eosinophilic fungal rhinosinusitis" (EFRS), "eosinophilic mucin rhinosinusitis" (EMRS) and mucosal invasion by hyphae in few patients have increased the problem to delineate the disease. Various hypotheses exist for etiopathogenesis of AFRS with considerable overlap, though recent extensive studies have made certain in depth understanding. The diagnosis of AFRS is a multi-disciplinary approach including the imaging, histopathology, mycology and immunological investigations. Though there is no uniform management protocol for AFRS, surgical clearing of the sinuses with steroid therapy are commonly practiced. The role of antifungal agents, leukotriene antagonists and immunomodulators is still questionable. The present review covers the controversies, recent advances in pathogenesis, diagnosis, and management of AFRS.

Cellular and molecular mechanisms of chronic rhinosinusitis and potential therapeutic strategies: review on cytokines, nuclear factor kappa B and transforming growth factor beta

BACKGROUND

Chronic rhinosinusitis is characterised by persistent inflammation of the sinonasal mucosa. Multiple pathophysiological mechanisms are likely to exist. Previous research has focused predominantly on T-helper type cytokines to highlight the inflammatory mechanisms. However, proteins such as nuclear factor kappa B and transforming growth factor beta are increasingly recognised to have important roles in sinonasal inflammation and tissue remodelling.

OBJECTIVE

This review article explores the roles of T-helper type cytokines, nuclear factor kappa B and transforming growth factor beta in the pathophysiological mechanisms of chronic rhinosinusitis. An understanding of these mechanisms will allow for better identification and classification of chronic rhinosinusitis endotypes, and, ultimately, improved therapeutic strategies.

Anthraquinone G503 induces apoptosis in gastric cancer cells through the mitochondrial pathway

G503 is an anthraquinone compound isolated from the secondary metabolites of a mangrove endophytic fungus from the South China Sea. The present study elucidates the anti-tumor activity and the underlying mechanism of G503. Cell viability assay performed in nine cancer cell lines and two normal cell lines demonstrated that the gastric cancer cell line SGC7901 is the most G503-sensitive cancer cells. G503 induced SGC7901 cell death via apoptosis. G503 exposure activated caspases-3, -8 and -9. Pretreatment with the pan-caspase inhibitor Z-VAD-FMK and caspase-9 inhibitor Z-LEHD-FMK, but not caspase-8 inbibitor Z-IETD-FMK, attenuated the effect of G503. These results suggested that the intrinsic mitochondrial apoptosis pathway, rather than the extrinsic pathway, was involved in G503-induced apoptosis. Furthermore, G503 increased the ratio of Bax to Bcl-2 in the mitochondria and decreased the ratio in the cytosol. G503 treatment resulted in mitochondrial depolarization, cytochrome c release and the subsequent cleavage of caspase -9 and -3. Moreover, it is reported that the endoplasmic reticulum apoptosis pathway may also be activated by G503 by inducing capase-4 cleavage. In consideration of the lower 50% inhibitory concentration for gastric cancer cells, G503 may serve as a promising candidate for gastric cancer chemotherapy.

COX/PGE(2) axis critically regulates effects of LPS on eosinophilia-associated cytokine production in nasal polyps

BACKGROUND

Lipopolysaccharide (LPS) has shown heterogeneous effects on eosinophilic inflammation in airways. However, little is known about how LPS regulates pathogenesis of chronic rhinosinusitis with nasal polyps, a major form of eosinophilic inflammation in the upper airway.

OBJECTIVE

We sought to investigate the effect of LPS on cytokine production by dispersed nasal polyp cells (DNPCs).

METHODS

Either diclofenac-treated or untreated DNPCs were cultured with or without staphylococcal enterotoxin B (SEB) in the presence or absence of LPS, after which the levels of IL-5, IL-13, IL-17A and IFN-γ within the supernatant were measured. The effects of PGE(2) on LPS-induced responses by diclofenac-treated DNPCs were also examined. LPS-induced PGE(2) production and mRNA expression of COX-1, COX-2 and microsomal PGE(2) synthase-1 (m-PGES-1) were measured.

RESULTS

Staphylococcal enterotoxin B induced IL-5, IL-13, IL-17A and IFN-γ production by DNPCs. Pre-treatment with LPS prior to SEB stimulation inhibited production of these cytokines. After stimulation with LPS, PGE(2) production and expression of COX-2 and m-PGES-1 mRNA by DNPCs increased significantly. In the presence of diclofenac, the suppressive effects of LPS were eliminated. LPS pre-treatment enhanced SEB-induced IL-5, IL-13 and IL-17A production in diclofenac-treated DNPCs, while addition of PGE(2) inhibited IL-5, IL-13 and IFN-γ production. LPS alone induced IL-5, IL-13 and IFN- γ production by diclofenac-treated DNPCs, while the addition of EP2 and EP4 receptor-selective agonists, as well as PGE(2) itself, inhibited IL-5 and IL-13 production.

CONCLUSIONS AND CLINICAL RELEVANCE

These results suggest that the regulatory effects of LPS on eosinophilic airway inflammation are controlled via the COX-2/PGE(2) axis. For clinical implications, indiscreet use of non-steroidal anti-inflammatory drugs should be avoided in patients with chronic rhinosinusitis with nasal polyps.

Pathways analysis of molecular markers in chronic sinusitis with polyps

OBJECTIVE

To perform a comprehensive molecular pathways analysis of genes identified through genome-wide expression profiling and the published literature for chronic sinusitis with polyps.

STUDY DESIGN

Molecular pathways analysis.

SETTING

Academic medical center.

METHODS

A molecular pathways analysis of gene biomarkers discovered through hypothesis-driven and high-throughput molecular studies was performed. Genes identified with a PubMed literature search were analyzed with Ingenuity Pathways Analysis software to identify central molecules implicated in the pathogenesis of chronic sinusitis with polyps. The central pathways were then compared with those identified through genome-wide expression profiling of ethmoid polyps.

RESULTS

A total of 97 molecules were investigated with Ingenuity Pathways Analysis based on 55 studies that evaluated differences in gene expression (39), genetic variation (12), or proteomics (4). The analysis revealed 9 statistically significant molecular networks containing central nodes that included transcription factors, protein kinases, cytokines, and growth factors/receptors. The highest scoring networks implicated nuclear factor kappa-B, tumor necrosis factor, and mitogen-activated protein kinases. The majority of pathways in the literature review analysis overlapped with those identified through a single genome-wide expression study.

CONCLUSIONS

Chronic sinusitis with polyps is a complex disease with suspected contribution of multiple genetic and environmental factors. The search for causative genes has led to the discovery of numerous candidates. Pathways analysis applied to these candidate genes identified common central molecules that are likely to be key mediators of the disease process. Novel therapies targeting these molecules may be applicable for the treatment of chronic sinusitis with polyps.

ERK pathway activation is required for amyloid-β(1-40)(-)induced neurotoxicity of THP-1 human monocytes towards SK-N-SH neuroblastoma

Alzheimer's disease (AD) is characterized by amyloid-β peptide deposition, increased activated microglia, and progressive loss of neurons in the brain. Although Aβ₁₋₄₀ can elicit inflammation in microglia, the intracellular signaling events mediating these effects are poorly defined. Here we show that cell-free supernatant from Aβ₁₋₄₀-treated THP-1 monocytes induced cytotoxicity towards neuroblastoma SK-N-SH cells. Exposure of THP-1 monocytes to Aβ₁₋₄₀ leads to increased tyrosine phosphorylation and extracellular signaling-regulated kinase (ERK) and increased levels of inflammatory cytokines (IL-1β, IL-8, and TNF-α) in the supernatant of THP-1 monocytes. Pretreatment of THP-1 monocytes with either a protein tyrosine kinase (PTK) inhibitor or an ERK inhibitor protects SK-N-SH cells from the cytotoxic effect of conditional supernatant from Aβ₁₋₄₀-treated THP-1 monocytes. Aβ₁₋₄₀-treated THP-1 monocytes also lead to upregulation of cyclooxygenase-2 and iNOS expression and increased of nitric oxide production. These results suggest that Aβ₁₋₄₀-induced activation of PTK/MEK/ERK pathway in THP-1 monocytes leads to the release of inflammatory factors that are toxic to SK-N-SH cells and might contribute to the onset of AD.

Protection of LPS-induced murine acute lung injury by sphingosine-1-phosphate lyase suppression

A defining feature of acute lung injury (ALI) is the increased lung vascular permeability and alveolar flooding, which leads to associated morbidity and mortality. Specific therapies to alleviate the unremitting vascular leak in ALI are not currently clinically available; however, our prior studies indicate a protective role for sphingosine-1-phosphate (S1P) in animal models of ALI with reductions in lung edema. As S1P levels are tightly regulated by synthesis and degradation, we tested the hypothesis that inhibition of S1P lyase (S1PL), the enzyme that irreversibly degrades S1P via cleavage, could ameliorate ALI. Intratracheal instillation of LPS to mice enhanced S1PL expression, decreased S1P levels in lung tissue, and induced lung inflammation and injury. LPS challenge of wild-type mice receiving 2-acetyl-4(5)-[1(R),2(S),3(R),4-tetrahydroxybutyl]-imidazole to inhibit S1PL or S1PL(+/-) mice resulted in increased S1P levels in lung tissue and bronchoalveolar lavage fluids and reduced lung injury and inflammation. Moreover, down-regulation of S1PL expression by short interfering RNA (siRNA) in primary human lung microvascular endothelial cells increased S1P levels, and attenuated LPS-mediated phosphorylation of p38 mitogen-activated protein kinase and I-κB, IL-6 secretion, and endothelial barrier disruption via Rac1 activation. These results identify a novel role for intracellularly generated S1P in protection against ALI and suggest S1PL as a potential therapeutic target.

Anti-inflammatory effects of celecoxib in rat lungs with smoke-induced emphysema

Chronic airway inflammation is a characteristic feature of destructive cigarette smoking (CS)-induced lung disease, particularly in patients with emphysema. Celecoxib, a specific cyclooxygenase-2 (COX-2) inhibitor, is widely used to treat inflammation. However, the exact mechanisms underlying this drug's anti-inflammatory effects have not yet been determined in pulmonary emphysema. Here, we explore whether celecoxib attenuates CS-induced inflammation in rat lungs. Rats were exposed to smoke and received celecoxib via intragastric feeding daily for 20 wk. We found that celecoxib inhibited interalveolar wall distance and pulmonary inflammation in the lungs of CS-treated rats. Celecoxib inhibited serum NO production, iNOS, COX-2 expression, and PGE(2) production in CS-treated lung tissues. Our immunohistochemical data showed that CS-induced CD68 and COX-2 expression were inhibited by celecoxib. Furthermore, celecoxib attenuated the activation of phospho-IkappaBalpha and NF-kappaB in CS-treated rat lung. In addition, there was an inhibitory effect of celecoxib on the COX-2 expression and NF-kappaB activation in LPS-stimulated RAW 264.7 macrophages. Celecoxib also attenuated NF-kappaB activation in COX-2 siRNA-transfected RAW 264.7 macrophages. Thus, our findings suggest that the anti-inflammatory effects of celecoxib are mediated by its effects on NF-kappaB-regulated gene expression, which ultimately reduces the progression of CS-induced pulmonary emphysema.