Staphylococcal enterotoxin B induced expression of IL-17A in nasal epithelial cells and its association with pathogenesis of nasal polyposis

Pathophysiology and management of Staphylococcus aureus in nasal polyp disease

INTRODUCTION

Staphylococcus aureus (S. aureus) is a common pathogen that frequently colonizes the sinonasal cavity. Recent studies demonstrated the essential role of Staphylococcus aureus in the pathophysiology of uncontrolled severe chronic rhinosinusitis with nasal polyps (NP) by initiating an immune response to the germ and its products, resulting in type 2 inflammation.

AREAS COVERED

This review aims to summarize the evidence for the role of S. aureus in the development of NP disease including S. aureus-related virulence factors, the pathophysiologic mechanisms used by S. aureus, and the synergistic effects of S. aureus and other pathogens. It also describes the current management of S. aureus associated with NPs as well as potential therapeutic strategies that are used in clinical practice.

EXPERT OPINION

S. aureus is able to damage the nasal mucosal epithelial barrier, impair the clearance of the host immune system, and trigger adaptive and innate immune reactions which lead to the formation of inflammation and nasal polyp growth. Further studies should focus on the development of novel therapeutic strategies, such as biologics, bacteriophages, probiotics, and nanomedicine, which could be used to treat S. aureus and its immunological consequences in the future.

Effect of lipopolysaccharide and polyinosinic:polycytidylic acid in a murine model of nasal polyp

Several factors, including bacterial and viral infections, have been associated with rhinosinusitis and nasal tissue remodelling that may result in nasal polyp formation. However, the potential role of bacterial or viral stimuli triggering polyp development is unclear. Here, we used lipopolysaccharide (LPS) and polyinosinic:polycytidylic acid [poly(I:C)] in a murine model of allergic rhinosinusitis to compare different effects of bacterial- and virus-derived stimuli in the pathogenesis of nasal polyp formation. Briefly, BALB/c mice were sensitised and challenged with ovalbumin and staphylococcal enterotoxin, with or without LPS or poly(I:C), and the consequent histopathological profiles, cytokines, and systemic humoral responses were studied. While no significant differences in polyp formations and epithelial disruptions were observed among the experimental groups, the local cell recruitment patterns slightly differed in animals that received either LPS or poly(I:C). Additionally, the local immune environments generated by LPS or poly(I:C) stimulation varied. LPS stimulation induced a marked Th1/Th17 response and predominantly neutrophilic nasal polyp formations, whereas poly(I:C) induced a Th2-skewed environment in neutrophilic nasal polyp development. Overall, our findings show that both cell recruitment patterns and local immune environments induced by these two stimuli differ, which may have implications in the physiopathology of rhinosinusitis with nasal polyp.

Adults with inflammatory bowel disease are at a greater risk of developing chronic rhinosinusitis: A nationwide population-based study

BACKGROUND

Both inflammatory bowel disease (IBD) and chronic rhinosinusitis (CRS) are characterised by dysregulated immune responses. Though previous studies have demonstrated the coexistence of IBD and CRS, investigations of their association using large sets of epidemiologic data are lacking.

METHODS

We examined IBD and the subsequent risk of CRS in a nationwide setting. For 1 January 2000 to 31 December 2010, we identified in the National Health Insurance Dataset of Taiwan a total of 8313 patients over the age of 20 years with IBD. We randomly extracted 33 252 cases without IBD to create a comparison group matching patients by age, sex and index year. Cumulative incidences were obtained using the Kaplan-Meier method, and we calculated risk estimates for the development of CRS using the Cox proportional hazards model.

RESULTS

In 295 007 person-years, we identified 521 (1.25%) cases of IBD. The IBD cohort had a 1.26-fold (95% confidence interval [CI], 1.17-1.35) greater risk of developing CRS than the comparison group; for ulcerative colitis, it was 1.73-fold (95% CI, 1.48-2.05) and for Crohn's disease it was 1.20-fold (95% CI = 1.11-1.29). Subsequent analysis stratified by age revealed that the risk was highest among the population with IBD aged 50 to 64 years (adjusted hazard ratio = 1.37; 95% CI, 1.18-1.59). A follow-up-specific analysis demonstrated that the risk appeared to be highest with a follow-up duration of less than 2 years.

CONCLUSION

The present analysis indicates that personal history of IBD, especially the phenotype ulcerative colitis, is associated with increased risk of subsequent CRS.

Manipulation of Innate and Adaptive Immunity by Staphylococcal Superantigens

Staphylococcal superantigens (SAgs) constitute a family of potent exotoxins secreted by Staphylococcus aureus and other select staphylococcal species. SAgs function to cross-link major histocompatibility complex (MHC) class II molecules with T cell receptors (TCRs) to stimulate the uncontrolled activation of T lymphocytes, potentially leading to severe human illnesses such as toxic shock syndrome. The ubiquity of SAgs in clinical S. aureus isolates suggests that they likely make an important contribution to the evolutionary fitness of S. aureus. Although the apparent redundancy of SAgs in S. aureus has not been explained, the high level of sequence diversity within this toxin family may allow for SAgs to recognize an assorted range of TCR and MHC class II molecules, as well as aid in the avoidance of humoral immunity. Herein, we outline the major diseases associated with the staphylococcal SAgs and how a dysregulated immune system may contribute to pathology. We then highlight recent research that considers the importance of SAgs in the pathogenesis of S. aureus infections, demonstrating that SAgs are more than simply an immunological diversion. We suggest that SAgs can act as targeted modulators that drive the immune response away from an effective response, and thus aid in S. aureus persistence.

Induction of specific T helper-9 cells to inhibit glioma cell growth

The effects of Staphylococcal enterotoxin B (SEB) on regulation of immune response have been recognized; whether SEB can enhance the effects of immunotherapy on glioma remains to be investigated. This study tests a hypothesis that administration with SEB enhances the effects of specific immunotherapy on glioma growth in mice. In this study, a glioma-bearing mouse model was developed by adoptive transfer with GL261 cells (a mouse glioma cell line). The mice were treated with the GL261 cell extracts (used as an Ag) with or without administration of SEB. We observed that treating glioma-bearing mice with the glioma Ag and SEB induced glioma-specific Th9 cells in both glioma tissue and the spleen. Treating CD4⁺ CD25⁻ T cells with SEB increased p300 phosphorylation, histone H3K4 acetylation at the interleukin (IL)-9 promoter locus, and increased the IL-9 transcriptional factor binding to the IL-9 promoter. Treating CD4⁺ CD25⁻ T cells with both SEB and glioma Ag induced glioma-specific Th9 cells. The glioma-specific Th9 cells induced glioma cell apoptosis in the culture. Treating the glioma-bearing mice with SEB and glioma Ag significantly inhibited the glioma growth. In conclusion, SEB plus glioma Ag immunotherapy inhibits the experimental glioma growth, which may be a novel therapeutic remedy for the treatment of glioma.

Inhibition of fracture healing in the presence of contamination by Staphylococcus aureus: Effects of growth state and immune response

Extremity injuries comprise a significant portion of trauma, affecting quality of life, financial burden, and return to duty. Bacterial contamination is commonly associated with failure to heal, despite antibiotic treatment, suggesting that additional therapies must be developed to combat these complications. Treatment failure is likely due to the presence of resistant microbial communities known as biofilms. Biofilm bacteria are able to elicit a direct inhibition of healing through a multitude of known factors. However, they likely also inhibit healing through alteration of the inflammatory response. As inflammation is a critical step in fracture healing, how the presence of biofilm bacteria shifts this response to one that is suboptimal for healing is an important consideration that is currently understudied. The profile of inflammatory factors in response to biofilm bacteria is unique and distinct from those induced during normal healing or by planktonic bacteria alone. This review will examine the presence of inflammatory factors during normal healing and those induced by contaminating bacteria, and will discuss how these differences may ultimately lead to nonunion. Specifically, this review will focus on the Th1/Th2/Th17 type inflammatory responses and how shifts in the balance of these responses during infection can lead to both ineffective clearance and disruption of fracture healing. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1845-1854, 2017.

Interleukin-17A-induced inflammation does not influence the development of nasal polyps in murine model

BACKGROUND

Nasal polyposis associated with chronic rhinosinusitis (CRS) is a chronic inflammatory disease that is characterized by infiltration of many inflammatory cells. Meanwhile, interleukin (IL)-17A is a well-known proinflammatory cytokine that induces both eosinophilic and neutrophilic inflammation. We investigated the role of IL-17A in the development of nasal polyps in the CRS murine model.

METHODS

Eosinophilic CRS with nasal polyps was induced by using ovalbumin (OVA) and Staphylococcus aureus enterotoxin B (SEB) in wild-type BALB/c and IL-17A knockout (KO) mice. Histopathologic changes of the sinonasal cavity were evaluated using hematoxylin and eosin, Periodic acid-Schiff, Sirius red, Masson's trichrome, and immunohistochemistry. The levels of total and OVA-specific immunoglobulin Es (IgEs) in sera were measured using enzyme-linked immunosorbent assay. The expression levels of IL-4, IL-5, and interferon-γ (IFN-γ) in the nasal mucosa were assessed by quantitative real-time polymerase chain reaction.

RESULTS

Under the IL-17A deficiency, total and OVA-specific IgEs in sera were reduced significantly. Infiltration of both eosinophils and neutrophils into the nasal mucosa, subepithelial fibrosis, and goblet cell count also decreased significantly in IL-17A KO mice treated with both OVA and SEB compared with those in the wild-type counterpart. However, there were no significant differences in the number of polypoid lesions among groups. Meanwhile, IL-4 increased and IFN-γ decreased in the nasal mucosa in IL-17A KO mice treated with both OVA and SEB.

CONCLUSION

This study suggests that even though IL-17A plays an important role in both nasal inflammation and remodeling, it does not influence the development of nasal polypoid lesions.

Role of the aryl hydrocarbon receptor in the pathogenesis of chronic rhinosinusitis with nasal polyps

A predominant Th17 population is a marker of chronic rhinosinusitis with nasal polyps (CRSwNP) in Chinese patients. As a ligand-activated transcription factor, the aryl hydrocarbon receptor (AhR) plays a vital role in promoting or inhibiting specific Th cell development. However, its role in CRSwNP remains to be defined. The aim of the present study was to investigate whether AhR, which regulates Th17 cell differentiation, played a role in the pathogenesis of CRSwNP by evaluating AhR expression in nasal polyps and peripheral blood mononuclear cells (PBMCs) obtained from CRSwNP patients. Forty-eight patients (atopic, 24; non-atopic, 24) and 13 controls were studied. To explore the role of AhR in CRSwNP, we analyzed the expression of AhR, retinoid-related orphan receptor C (RORC), interleukin (IL)-17, and IL-10 and the differentiation of Th17 using mRNA or protein detection methods. Notably, the expression of AhR was reduced in CRSwNP, and the expression of AhR was lower in the atopic group than in the non-atopic group. However, there was a very low level of Th17 and its associated factors (RORC, IL-17) in the control group compared to the two CRSwNP groups. In particular, the polarization of Th17 cells in atopic CRSwNP patients was increased compared with non-atopic individuals. In addition, ITE intervention in PBMCs promoted AhR expression and attenuated Th17 responses, demonstrating that AhR was more likely to suppress Th17 cells differentiation in Chinese CRSwNP patients. This information is valuable for obtaining a clear understanding of the pathogenesis of CRSwNP. Moreover, patients with atopic CRSwNP may exhibit reduced expression of AhR, leading to aggravation of the disproportionate distribution of Th17 cells in polyp tissues and PBMCs, thereby suggesting that atopic CRSwNP has a distinct pathogenesis from that of non-atopic CRSwNP.