Regulation of immunoglobulin secretion by plasma cells infiltrating nasal polyps

The Role of IgA in Chronic Upper Airway Disease: Friend or Foe?

Chronic upper airway inflammation is amongst the most prevalent chronic disease entities in the Western world with prevalence around 30% (rhinitis) and 11% (rhinosinusitis). Chronic rhinitis and rhinosinusitis may severely impair the quality of life, leading to a significant socio-economic burden. It becomes more and more clear that the respiratory mucosa which forms a physiological as well as chemical barrier for inhaled particles, plays a key role in maintaining homeostasis and driving disease. In a healthy state, the mucosal immune system provides protection against pathogens as well as maintains a tolerance toward non-harmful commensal microbes and benign environmental substances such as allergens. One of the most important players of the mucosal immune system is immunoglobulin (Ig) A, which is well-studied in gut research where it has emerged as a key factor in creating tolerance to potential food allergens and maintaining a healthy microbiome. Although, it is very likely that IgA plays a similar role at the level of the respiratory epithelium, very little research has been performed on the role of this protein in the airways, especially in chronic upper airway diseases. This review summarizes what is known about IgA in upper airway homeostasis, as well as in rhinitis and rhinosinusitis, including current and possible new treatments that may interfere with the IgA system. By doing so, we identify unmet needs in exploring the different roles of IgA in the upper airways required to find new biomarkers or therapeutic options for treating chronic rhinitis and rhinosinusitis.

Immunoglobulins and Transcription Factors in Otitis Media

The causes of otitis media (OM) involve bacterial and viral infection, anatomo-physiological abnormalities of the Eustachian canal and nasopharynx, allergic rhinitis, group childcare centers, second-hand smoking, obesity, immaturity and defects of the immune system, formula feeding, sex, race, and age. OM is accompanied by complex and diverse interactions among bacteria, viruses, inflammatory cells, immune cells, and epithelial cells. The present study summarizes the antibodies that contribute to immune reactions in all types of otitis media, including acute otitis media, otitis media with effusion, and chronic otitis media with or without cholesteatoma, as well as the transcription factors that induce the production of these antibodies. The types and distribution of B cells; the functions of B cells, especially in otorhinolaryngology; antibody formation in patients with otitis media; and antibodies and related transcription factors are described. B cells have important functions in host defenses, including antigen recognition, antigen presentation, antibody production, and immunomodulation. The phenotypes of B cells in the ear, nose, and throat, especially in patients with otitis media, were shown to be CD5^low, CD23^high, CD43^low, B220^high, sIgM^low, sIgD^high, Mac-1^low, CD80(B7.1)^low, CD86(B7.2)^low, and Syndecam-1^low. Of the five major classes of immunoglobulins produced by B cells, three (IgG, IgA, and IgM) are mainly involved in otitis media. Serum concentrations of IgG, IgA, and IgM are lower in patients with OM with effusion (OME) than in subjects without otitis media. Moreover, IgG, IgA, and IgM concentrations in the middle ear cavity are increased during immune responses in patients with otitis media. B cell leukemia/lymphoma-6 (Bcl-6) and paired box gene 5 (Pax-5) suppress antibody production, whereas B lymphocyte inducer of maturation program 1 (Blimp-1) and X-box binding protein 1 (XBP-1) promote antibody production during immune responses in patients with otitis media.

A Recently Established Murine Model of Nasal Polyps Demonstrates Activation of B Cells, as Occurs in Human Nasal Polyps

Animal model systems are invaluable for examining human diseases. Our laboratory recently established a mouse model of nasal polyps (NPs) and investigated similarities and differences between this mouse model and human NPs. We especially focus on the hypothesis that B cell activation occurs during NP generation in the murine model. After induction of ovalbumin-induced allergic rhinosinusitis, 6% ovalbumin and Staphylococcus aureus enterotoxin B (10 ng) were instilled into the nasal cavity of mice three times per week for 8 weeks. The development of structures that somewhat resemble NPs (which we will refer to as NPs) was confirmed by hematoxylin and eosin staining. The mRNA and protein levels of various inflammatory cell markers and mediators were measured by real-time PCR in nasal tissue and by ELISA in nasal lavage fluid (NLF), respectively. Total Ig isotype levels in NLF were also quantitated using the Mouse Ig Isotyping Multiplex kit (EMD Millipore, Billerica, MA) on a Luminex 200 instrument (Life Technologies, Grand Island, NY). Similar to human NPs, there were significant increases in gene expression of inflammatory cell markers, such as CD19, CD138, CD11c, and mast cell protease-6 in nasal tissue samples of the NP group compared with those of the control group. In further investigations of B cell activation, mRNA expressions of B cell activating factor and a proliferation-inducing ligand were found to be significantly increased in mouse NP tissue. B cell-activating factor protein concentration and IgA and IgG1 levels in NLF were significantly higher in the NP group compared with the control group. In this study, the NP mouse model demonstrated enhanced B cell responses, which are reminiscent of B cell responses in human NPs.

C-C Chemokine Ligand 2 Gene Expression in Nasal Polyp Fibroblasts: Possible Implication in the Pathogenesis of Nasal Polyposis

Objectives:

Recruitment of macrophages is essential to the pathogenesis of nasal polyps (NP), since this disease is inflammation-related. In this study, the effects of tumor necrosis factor α (TNF-α) on the expression of C-C chemokine ligand 2 (CCL2) in fibroblasts derived from nasal polyps (NPFs) were investigated. The roles of cyclooxygenase (COX) 2 and prostaglandins in the mediation of TNF-α–stimulated CCL2 gene expression were also investigated.

Methods:

Northern blot analysis was used to study the expression of CCL2 and c-Fos in cultured NPFs. An electrophoretic mobility shift assay was used to explore the interactions between activator protein 1 (AP-1) and DNA. Immunohistochemistry was used to explore the in vivo expressions of COX-2, CCL2, and CD68 in NPs.

Results:

The Northern blot analysis showed that TNF-α stimulated the expression of CCL2 and COX-2 genes, and the synthesis of CCL2 messenger RNA was COX-2-dependent. A transient elevation of c-Fos and c-Jun messenger RNAs was induced by TNF-α, whereas COX-2 inhibitors NS-398 and meloxicam abolished the up-regulation of c-Fos. The electrophoretic mobility shift assay revealed that TNF-α triggered AP-1 and DNA binding and again, NS-398 and meloxicam inhibited this reaction via reducing c-Fos synthesis. Curcumin (AP-1 inhibitor) markedly suppressed the TNF-α–induced CCL2 expression. The immunohistochemical staining of NP surgical specimens also revealed an intimate alignment between CCL2-positive fibroblasts and CD-68-positive macrophages.

Conclusions:

These data suggest that NPFs may contribute to NP development by synthesizing CCL2 to promote macrophage recruitment. Furthermore, COX-2 facilitates CCL2 transcription in NPFs via a c-Fos and AP-1 signaling pathway.

Local increase in IgE and class switch recombination to IgE in nasal polyps in chronic rhinosinusitis

BACKGROUND

Chronic rhinosinusitis with nasal polyps is generally characterized by local Th2 inflammation and is categorized into two subtypes in Japan: eosinophilic chronic rhinosinusitis (similar to chronic rhinosinusitis with nasal polyps in western countries) and non-eosinophilic chronic rhinosinusitis (characterized by Th1-dominant inflammation).

OBJECTIVE

To investigate local IgE production and class switch recombination to IgE in these two subtypes of chronic rhinosinusitis with nasal polyps.

METHODS

The identity of IgE-positive cells was determined using double-immunofluorescent staining for IgE and cell-type-specific molecular markers. To investigate the local class switch recombination to IgE and IgE synthesis in the mucosa, we performed real-time polymerase chain reaction to examine the mRNA expression of Th2 cytokines and class-switch-related molecules, including IL-4, IL-5, IL-13, ε germline gene transcripts, IgE mature transcript, IgG mature transcript, RAG1, RAG2 and activation-induced cytidine deaminase in eosinophilic polyps, non-eosinophilic polyps and controls.

RESULTS

The concentrations of total IgE and number of IgE-positive cells were significantly higher in the eosinophilic polyps compared with control and non-eosinophilic polyps. IgE-positive cells were predominantly mast cells in eosinophilic polyps and significantly correlated with the number of FcεR1-positive cells in the subepithelial layer. IL-5 and IL-13 mRNA and ε germline gene transcripts expression levels were significantly higher in eosinophilic polyps compared with control and non-eosinophilic polyps. In contrast, the number of plasma cells and the expression of IgG mature transcripts were increased in non-eosinophilic polyps compared with eosinophilic polyps. RAG2 mRNA was significantly increased in both eosinophilic and non-eosinophilic polyps compared with control mucosa.

CONCLUSION AND CLINICAL RELEVANCE

The current study suggests local class switching to IgE, production of IgE and IgE localization to the surface of mast cells in eosinophilic chronic rhinosinusitis in the Japanese population. The difference in the IgE-related profiles between eosinophilic chronic rhinosinusitis and non-eosinophilic chronic rhinosinusitis suggests heterogeneity in the pathogenesis of chronic rhinosinusitis with nasal polyps.

Cellular comparison of sinus mucosa vs polyp tissue from a single sinus cavity in chronic rhinosinusitis

BACKGROUND

Nasal polyposis is a common development in chronic rhinosinusitis (CRS), and sinus mucosa and polyp tissue have been used interchangeably in studies investigating CRS. However, potential differences may exist between these 2 tissue types, which have not been entirely characterized.

METHODS

A cross-sectional study of CRS with nasal polyposis (CRSwNP) patients undergoing endoscopic sinus surgery was conducted. Sinus mucosal biopsies and corresponding polyp tissue were obtained from the same sinus cavity via flow cytometry, single-cell suspensions identified type 2 innate lymphoid cells (ILC2s), CD4 and CD8 T cells, activated CD4 and CD8 T cells, plasma cells, plasmacytoid dendritic cells (pDCs), regulatory T cells, T follicular helper cells, B cells, and immunoglobulin A (IgA)(+) and IgG(+) B cells. Cells were measured as a percentage of CD45(+) cells. Paired nonparametric comparisons between sinus and polyp tissue were performed.

RESULTS

Ten patients (50% female; age 48 ± 16 years) were recruited. Significantly elevated ILC2 levels were found in polyp tissue compared to sinus mucosa (0.12 [0.07 to 0.23] vs 0.07 [0.04 to 0.16], p = 0.02), as well as plasma cells (2.25 [0.84 to 3.68] vs 1.18 [0.74 to 2.41], p = 0.01); pDCs (0.15 [0.12 to 0.50[ vs 0.04 [0.02 to 0.17], p = 0.03); activated CD8 T cells (29.22 [17.60 to 41.43] vs 16.32 [10.07 to 36.16], p = 0.04) and IgG(+) B cells (6.96 [0.06 to 11.82] vs 1.51 [0.38 to 5.13], p = 0.04). Other cell populations showed no significant differences.

CONCLUSION

Polyps have a similar cellular composition to that of mucosa. Higher levels of ILC2s, plasma cells, pDCs, activated CD8 T cells, and IgG(+) B cells in polyp tissue may be reflective of cell populations driving nasal polyp development. The cellular machinery of CRS is present in polyps and representative of the disease process. This pilot study strongly suggests that a larger study would provide significant insights into the relationship of sinus mucosa to pathogenesis of nasal polyps.

B-lymphocyte lineage cells and the respiratory system

Adaptive humoral immune responses in the airways are mediated by B cells and plasma cells that express highly evolved and specific receptors and produce immunoglobulins of most isotypes. In some cases, such as autoimmune diseases or inflammatory diseases caused by excessive exposure to foreign antigens, these same immune cells can cause disease by virtue of overly vigorous responses. This review discusses the generation, differentiation, signaling, activation, and recruitment pathways of B cells and plasma cells, with special emphasis on unique characteristics of subsets of these cells functioning within the respiratory system. The primary sensitization events that generate B cells responsible for effector responses throughout the airways usually occur in the upper airways, tonsils, and adenoid structures that make up the Waldeyer ring. On secondary exposure to antigen in the airways, antigen-processing dendritic cells migrate into secondary lymphoid organs, such as lymph nodes, that drain the upper and lower airways, and further B-cell expansion takes place at those sites. Antigen exposure in the upper or lower airways can also drive expansion of B-lineage cells in the airway mucosal tissue and lead to the formation of inducible lymphoid follicles or aggregates that can mediate local immunity or disease.

Chronic rhinosinusitis with nasal polyps is characterized by B-cell inflammation and EBV-induced protein 2 expression

BACKGROUND

Despite the high prevalence and morbidity of chronic rhinosinusitis (CRS), little is known about the mechanisms that underlie its pathogenesis. Recent studies have suggested that B cells might play an important role in CRS.

OBJECTIVE

We sought to thoroughly characterize B lineage cells within sinus tissues of patients with CRS and healthy control subjects and to determine whether levels of EBV-induced protein 2, which is known to play an important role in the development of B-cell responses, were increased in patients with CRS.

METHODS

Cells isolated from sinus tissues of patients with CRS and healthy control subjects were characterized by means of flow cytometry and immunohistochemistry. Local production of antibodies was measured in tissue extracts, nasal lavage fluid, and sera by using multiplex bead arrays and ELISA. Quantitative RT-PCR, ELISA, and Western blotting were used to assess gene and protein expression from tissue extracts.

RESULTS

Nasal polyps (NPs) from patients with CRS had increased levels of both B cells and plasma cells compared with uncinate tissue from healthy control subjects (P<.05). NPs also contained significantly increased levels of several antibody isotypes compared with normal uncinate tissue (P<.05), but no differences in circulating antibody levels were found. Interestingly, levels of EBV-induced protein 2 were also increased in NPs (P<.05) and were positively correlated with expression of plasma cell markers (CD138 and B lymphocyte-induced maturation protein) in sinus tissue.

CONCLUSION

B cells and plasma cells are enriched in NPs, actively produce antibodies locally, and might contribute to chronic inflammation in patients with CRS. Elucidating the mechanisms that underlie this excessive local B-cell response might provide novel insights for the development of improved therapeutic strategies.

Perspectives on the etiology of chronic rhinosinusitis: an immune barrier hypothesis

BACKGROUND

Chronic rhinosinusitis (CRS) has been defined as persistent symptomatic inflammation of the nasal and sinus mucosa resulting from the interaction of multiple host and environmental factors. Recent studies have implicated Alternaria fungi or toxigenic Staphylococcus aureus as critical agents in CRS pathogenesis. The emphasis on environmental agents in CRS etiology has focused interest toward elimination of those agents as the prime mechanism of therapy. This viewpoint is in marked contrast to the current perspective on some other chronic inflammatory epithelial disorders that afflict the skin, lungs, and gut, wherein host factors are believed to predispose to disease expression in the presence of ubiquitous environmental agents.

METHODS

The current review evaluates CRS etiology from this perspective and considers that CRS develops, in part, as an outcome of a dysfunctional host response. Specifically, evidence from our laboratory and others will be reviewed indicating that CRS is associated with a failure of the mechanical and immunologic barriers across the nasal mucosa. The hypothesis would further propose that genetic and epigenetic variation predisposes susceptible individuals to barrier failure in the presence of environmental stress leading to CRS.

RESULTS

From this unifying perspective, bacteria and fungi are seen as disease modifiers rather than primary etiologic agents.

CONCLUSION

The goal is to place concepts of CRS pathophysiology in a framework consistent with a current understanding of chronic inflammation in general and epithelial disease in particular.

Tumor necrosis factor-alpha stimulates the expression of C-C chemokine ligand 2 gene in fibroblasts from the human nasal polyp through the pathways of mitogen-activated protein kinase

BACKGROUND

Recruitment of macrophages is crucial to the pathogenesis of the nasal polyp (NP) because this disease is believed to be inflammation related. Information regarding the expression of C-C chemokine ligand 2 (CCL2), an essential modulator of monocyte chemotaxis in nasal polyp fibroblasts (NPFs), remains unavailable. In this study, the effects of tumor necrosis factor (TNF)-a on CCL2 expression in NPFs and the signaling pathway involved were investigated.

METHODS

Primary cultures of NPFs were established from NPs. The expressions of CCL2, c-Fos, and c-Jun mRNAs in NPF after TNF-a stimulation were detected by Northern blot. Western blot was used to examine the activation of mitogen-activated protein kinase (MAPK) signaling pathways. Activator protein (AP) 1/DNA interactions were evaluated by electrophoretic mobility shift assay (EMSA).

RESULTS

Northern blot showed that TNF-alpha stimulated CCL2 gene expression in NPFs. Significant increase of B-Raf, phosphorated MAPK including mitogen-activated ERK-activate kinase (MEK)1/2, extracellular signal-related kinase 1/2, and p38 were detected by Western blot. c-Fos and c-Jun mRNAs were induced by TNF-alpha, and PD98059 (MEK inhibitor) and SB203580 (p38 inhibitor) abolished the up-regulation of c-Fos. EMSA revealed that TNF-a increased AP-1/DNA binding, and PD98059 and SB203580 attenuated this reaction, possibly via reducing c-Fos synthesis. PD98059 and curcunmin (AP-1 inhibitor) markedly suppressed the TNF-alpha-induced CCL2 expression, whereas the effect of SB203580 was less noted.

CONCLUSION

TNF-alpha induces CCL2 transcription in NPFs. B-Raf/MEK/ERK signaling cascade and to a less extent the p38 pathway are responsible for c-Fos activation and the subsequent AP-1/DNA interaction leading to CCL2 expression.

B cells in murine cervical lymph nodes are conventional B-2 cells

We investigated the characteristic features of cervical lymph node B cells to determine whether their behavior differs from that of B cells located elsewhere, because cervical lymph nodes may be exposed to continual antigenic stimulation from the naso- and/or oropharynx. B cells were isolated from cervical lymph nodes, spleen and peritoneal fluid of mice, cultured in medium, and exposed to various stimuli. The expression of various surface molecules characteristic of lymphoid B cells was assayed by flow cytometry, and immunoglobulin secreted into the culture supernatants was evaluated by enzyme-linked immunosorbent assay. B220+ cells were cultured in medium alone or with lipopolysaccharide, and their entrance into S phase in response to stimuli was measured by proliferative assays. Phenotypic characteristics of cervical lymph node B cells included CD5 low, CD23high, CD43low, B7.1low, B7.2low, and Syndecan-1low. Unstimulated lymphoid B cells did not secrete immunoglobulin, but, upon stimulation, secretion of IgM was increased more than secretion of IgA and IgG. B cells actively entered S phase after 48 hr stimulation. These results show that B cells in cervical lymph nodes are conventional B2 cells, like splenic B cells.

Characteristic features of B cells in murine cervical lymph nodes

CONCLUSION

B cells in cervical lymph nodes correspond to typical conventional B cells (B-2).

OBJECTIVE

The special status of cervical lymph nodes in relation to the oropharynx, and the need to maintain the integrity of the oropharnygeal mucosal barrier, suggest the possibility that cervical lymph node B cells located in the oropharynx may behave differently from B cells located elsewhere. In this study we examined the symmetry or lack thereof between cervical lymph node B cells and other B-cell subsets.

MATERIAL AND METHODS

We isolated B cells from murine cervical lymph node tissue and evaluated them in vitro according to several criteria.

RESULTS

We found that cervical lymph node B cells expressed typical B-cell phenotypic markers and proliferated normally in response to mitogenic stimulation. They did not spontaneously secrete immunoglobulin and, in keeping with this, did not express elevated levels of either CD138 (Syndecan-1), a marker for plasma cells, or BLIMP-1, a putative master regulator of B-cell differentiation.