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

Panax notoginseng saponin R1 improves glucocorticoid-inhibited airway epithelium repair via glucocorticoid receptor β

BACKGROUND

Panax notoginseng saponin R1(PNS-R1), derived from Panax notoginseng roots, promotes wound repair, whereas glucocorticoids can inhibit the repair of airway epithelial damage in asthma.

OBJECTIVE

This study investigated whether PNS-R1 counteracts the inhibitory effects of glucocorticoids on the repair of airway epithelial damage in asthma.

METHODS

In vivo, female C57BL/6 mice were sensitized, challenged with house dust mites (HDM), and treated with dexamethasone, PNS-R1, and/or adenovirus GRβ-shRNA. Airway epithelium damage was examined using pathological sections of the trachea and bronchi, markers of airway inflammation, epithelial cells in bronchoalveolar lavage fluid, and expression of the E-cadherin protein. In vitro, we treated 16HBE cells with dexamethasone, PNS-R1, and/or GRβ-siRNA and detected cell proliferation and migration. The expression of GRβ and key components of MKP-1 and Erk1/2 were detected by western blotting.

RESULTS

In vivo, PNS-R1 reduced airway inflammation, hyperresponsiveness, and mucus hypersecretion; the combination of PNS-R1 and dexamethasone promoted airway epithelial integrity and reduced cell detachment. In vitro, PNS-R1 alleviated the inhibition of bronchial epithelial cell growth, migration, and proliferation by dexamethasone; PNS-R1 promoted GRβ expression, inhibited MKP-1 protein expression, and activated MAPK signaling, thereby promoting airway epithelial cell proliferation and repair.

CONCLUSIONS

Panax notoginseng saponin R1 alleviated the inhibitory effect of dexamethasone on the repair of airway epithelial damage in asthmatic mice, likely by promoting the proliferation of airway epithelial cells by stimulating GRβ expression and activating the MAPK pathway.

Research progress of glucocorticoid resistance in chronic rhinosinusitis with nasal polyps: A review

Chronic rhinosinusitis with nasal polyps (CRSwNP) is one of the common chronic inflammatory diseases in otolaryngology. Glucocorticoid (GC) acts as the first-line drug for the treatment of CRSwNP in clinical practice, and they play an irreplaceable role in reducing nasal mucosal inflammation and restoring the normal physiological function of the nasal mucosa. However, many patients are still insensitive to GC treatment, known as GC resistance, which leads to poor control of the disease, and the underlying mechanisms are still not fully elucidated. This article provides a comprehensive overview of the research progress of GC resistance of patients with CRSwNP in recent years.

Ascorbic acid along with ciprofloxacin regulates S. aureus induced microglial inflammatory responses and oxidative stress through TLR-2 and glucocorticoid receptor modulation

Microglial inflammatory responses play a central role in the pathogenesis of S. aureus induced brain infections. Upon activation, microglia produces free radicals (ROS/RNS) and disrupts the cellular antioxidant defense to combat invading microorganisms. Despite conventional antibiotic or steroid therapy, microglial over-activation could not be controlled. So, an attempt had been taken by using a natural antioxidant ascorbic acid along with ciprofloxacin to regulate microglial over-activation by involving TLR-2 and glucocorticoid receptor (GR) in an in-vitro cell culture-based study. Combinatorial treatment during TLR-2 neutralization effectively reduced the bacterial burden at 60 min compared to the GR blocking condition (p < 0.05). Moreover, the infection-induced H₂O₂, O₂^.-, and NO release in microglial cell culture was diminished possibly by enhancing SOD and catalase activities in the same condition (p < 0.05). The arginase activity was markedly increased after TLR-2 blocking in the combinatorial group compared to single treatments (p < 0.05). Experimental results indicated that combinatorial treatment may act through up-regulating GR expression by augmenting endogenous corticosterone levels. However, better bacterial clearance could further suppress the TLR-2 mediated pro-inflammatory NF-κB signaling. From Western blot analysis, it was concluded that ciprofloxacin-ascorbic acid combination in presence of anti-TLR-2 antibody exhibited 81.25% inhibition of TLR-2 expression while the inhibition for GR was 3.57% with respect to the infected group. Therefore, during TLR-2 blockade ascorbic acid combination might be responsible for the restoration of redox balance in microglia via modulating TLR-2/GR interaction. The combination treatment could play a major role in the neuroendocrine-immune regulation of S. aureus induced microglial activation.

Expression Profiles of GILZ and Annexin A1 in Human Oral Candidiasis and Lichen Planus

Adrenal glands are the major source of glucocorticoids, but recent studies indicate tissue-specific production of cortisol, including that in the oral mucosa. Both endogenous and exogenous glucocorticoids regulate the production of several proteins, including the glucocorticoid-induced leucine zipper (GILZ) and Annexin A1, which play important roles in the regulation of immune and inflammatory responses. Common inflammation-associated oral conditions include lichen planus and candidiasis, but the status of GILZ and Annexin A1 in these human conditions remains to be established. Accordingly, archived paraffin-embedded biopsy samples were subjected to immunohistochemistry to establish tissue localization and profile of GILZ and Annexin A1 coupled with the use of hematoxylin–eosin stain for histopathological assessment; for comparison, fibroma specimens served as controls. Histopathological examination confirmed the presence of spores and pseudohyphae for oral candidiasis (OC) specimens and marked inflammatory cell infiltrates for both OC and oral lichen planus (OLP) specimens compared to control specimens. All specimens displayed consistent and prominent nuclear staining for GILZ throughout the full thickness of the epithelium and, to varying extent, for inflammatory infiltrates and stromal cells. On the other hand, a heterogeneous pattern of nuclear, cytoplasmic, and cell membrane staining was observed for Annexin A1 for all specimens in the suprabasal layers of epithelium and, to varying extent, for inflammatory and stromal cells. Semi-quantitative analyses indicated generally similar fractional areas of staining for both GILZ and Annexin A1 among the groups, but normalized staining for GILZ, but not Annexin A1, was reduced for OC and OLP compared to the control specimens. Thus, while the cellular expression pattern of GILZ and Annexin A1 does not differentiate among these conditions, differential cellular profiles for GILZ vs. Annexin A1 are suggestive of their distinct physiological functions in the oral mucosa.

From "Leaky Gut" to Impaired Glia-Neuron Communication in Depression

In the last three decades, the robust scientific data emerged, demonstrating that the immune-inflammatory response is a fundamental component of the pathophysiology of major depressive disorder (MDD). Psychological stress and various inflammatory comorbidities contribute to such immune activation. Still, this is not uncommon that patients with depression do not have defined inflammatory comorbidities, and alternative mechanisms of immune activation need to take place. The gastrointestinal (GI) tract, along with gut-associated lymphoid tissue (GALT), constitutes the largest lymphatic organ in the human body and forms the biggest surface of contact with the external environment. It is also the most significant source of bacterial and food-derived antigenic material. There is a broad range of reciprocal interactions between the GI tract, intestinal microbiota, increased intestinal permeability, activation of immune-inflammatory response, and the CNS that has crucial implications in brain function and mental health. This intercommunication takes place within the microbiota-gut-immune-glia (MGIG) axis, and glial cells are the main orchestrator of this communication. A broad range of factors, including psychological stress, inflammation, dysbiosis, may compromise the permeability of this barrier. This leads to excessive bacterial translocation and the excessive influx of food-derived antigenic material that contributes to activation of the immune-inflammatory response and depressive psychopathology. This chapter summarizes the role of increased intestinal permeability in MDD and mechanisms of how the "leaky gut" may contribute to immune-inflammatory response in this disorder.

Increased lipopolysaccharide content is positively correlated with glucocorticoid receptor-beta expression in chronic rhinosinusitis with nasal polyps

Introduction

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a common and frequently occurring disease of the upper respiratory tract. The nasal instillation of the Gram‐negative (G⁻) bacterial product lipopolysaccharide (LPS) can induce not only acute sinusitis but also the development of CRSwNP in animal models. Nevertheless, the expression and distribution of LPS in patients with CRSwNP have not been investigated. And the study was to investigate the expression of LPS and its relationship with glucocorticoid receptors (GRs) in CRSwNP.

Methods

Multiple methods, including bacterial culture and immunohistochemistry, were used to detect and analyze nasal bacteria, plasma LPS content, and the levels of LPS and GR‐α/β, cluster of differentiation 68 (CD68), and myeloperoxidase (MPO) expression, as well as their relationship in CRSwNP.

Results

The number of G⁻ bacteria and Escherichia coli (E. coli) was not significantly different between CRSwNP subjects and the controls. However, the positive rate of LPS was much higher than that of E. coli in CRSwNP subjects and was significantly higher in noneosinophilic CRSwNP subjects than in eosinophilic CRSwNP subjects. Moreover, the LPS levels were positively correlated with GR‐β but not GR‐α expression in CRSwNP. Immunofluorescence assays showed that LPS was mainly detected in CD68⁺ macrophages and MPO⁺ neutrophils, in addition to histiocytes, in CRSwNP.

Conclusions

Persistent LPS in CRSwNP can lead to unresolved mucosal inflammation, eventually leading to tissue remodeling and the development of CRSwNP. Our findings suggest that increased LPS content and possible resistance to glucocorticoids may be one of the important pathogenic mechanisms of G⁻ bacteria in CRSwNP.

LPS regulates the expression of glucocorticoid receptor α and β isoforms and induces a selective glucocorticoid resistance in vitro

Background

This study was aimed to evaluate the effect of LPS in glucocorticoid receptor (GR) isoforms expression on different cell lines and PBMC from healthy donors in vitro and glucocorticoid sensitivity of PBMC in vitro.

Methods

U-2 OS cell lines expressing GR isoforms, different cell lines (CEM, RAJI, K562 and HeLa) or PBMC from healthy donors, were cultured or not with LPS. The expression of GRα and GRβ was evaluated by Western blot. Glucocorticoid sensitivity was evaluated in PBMC treated with LPS, testing genes which are transactivated or transrepressed by glucocorticoid. For transactivated genes (MKP1, FKBP5) PBMC were treated with Dexamethasone 100 nM for 6 h. The mRNA expression was measured by RT-PCR. For transrepressed genes (IL-8, GM-CSF), PBMC were cultured in Dexamethasone 100 nM and LPS 10 μg/ml for 6 h and protein expression was measure by ELISA.

Results

GR isoforms were induced in U-2 OS cells with a greater effect on GRα expression. Both isoforms were also induced in CEM cells with a tendency to a greater effect on GRβ. LPS induced only the expression of GRα in Raji and HeLa cells, and in PBMC, with no effect in K562 cells. LPS induced a loss of glucocorticoid inhibitory effect only on the secretion of GM-CSF.

Conclusion

LPS in vitro differentially modulates the expression of GR isoforms in a cell specific manner. In PBMC from healthy donors LPS induces an approximately two times increase in the expression of GRα and a loss of the glucocorticoid inhibitory effect on the secretion of GM-CSF, without affecting other glucocorticoid responses evaluated.

Electronic supplementary material

The online version of this article (10.1186/s12950-017-0169-0) contains supplementary material, which is available to authorized users.

On the translocation of bacteria and their lipopolysaccharides between blood and peripheral locations in chronic, inflammatory diseases: the central roles of LPS and LPS-induced cell death

We have recently highlighted (and added to) the considerable evidence that blood can contain dormant bacteria. By definition, such bacteria may be resuscitated (and thus proliferate). This may occur under conditions that lead to or exacerbate chronic, inflammatory diseases that are normally considered to lack a microbial component. Bacterial cell wall components, such as the endotoxin lipopolysaccharide (LPS) of Gram-negative strains, are well known as potent inflammatory agents, but should normally be cleared. Thus, their continuing production and replenishment from dormant bacterial reservoirs provides an easy explanation for the continuing, low-grade inflammation (and inflammatory cytokine production) that is characteristic of many such diseases. Although experimental conditions and determinants have varied considerably between investigators, we summarise the evidence that in a great many circumstances LPS can play a central role in all of these processes, including in particular cell death processes that permit translocation between the gut, blood and other tissues. Such localised cell death processes might also contribute strongly to the specific diseases of interest. The bacterial requirement for free iron explains the strong co-existence in these diseases of iron dysregulation, LPS production, and inflammation. Overall this analysis provides an integrative picture, with significant predictive power, that is able to link these processes via the centrality of a dormant blood microbiome that can resuscitate and shed cell wall components.