Clinical approaches for understanding the expression levels of pattern recognition receptors in otitis media with effusion

The Roles of NOD-like Receptors in Innate Immunity in Otitis Media

Acute otitis media (AOM) can persist or lead to various complications in individuals in which the innate immune system is impaired. In this context, impaired expression of nucleotide-binding oligomerization domain (NOD)-like receptor (NLR), an intracellular pathogen-recognition receptor (PRR), is involved in the etiology of OM in humans and animals, affecting its development, severity, chronicity, recurrence, and associated complications. To assess this relationship, we reviewed literature reports relating NLR expression patterns with the pathophysiology and clinical features of OM in the larger context of impaired innate immunity. We summarized the results of published studies on the expression of NLRs in animals and humans in acute otitis media (AOM), otitis media with effusion (OME), chronic otitis media (COM) with cholesteatoma, and COM without cholesteatoma. NLRs were expressed mainly in association with bacterial infection in AOM, OME, COM with cholesteatoma, and COM without cholesteatoma. In addition, expression of NLRs was affected by the presence or absence of bacteria, fluid characteristics, disease recurrence, tissue type, and repeated surgery. Various factors of the innate immune system are involved in the pathogenesis of OM in the middle ear. NLRs are expressed in AOM, OME, COM with cholesteatoma, and COM without cholesteatoma. Impaired NLR expression induced the development, chronicity and recurrence of OM and exacerbated associated complications, indicating that NLRs have important roles in the pathogenesis of OM.

Toll-Like Receptors: Expression and Roles in Otitis Media

Otitis media is mainly caused by upper respiratory tract infection and eustachian tube dysfunction. If external upper respiratory tract infection is not detected early in the middle ear, or an appropriate immune response does not occur, otitis media can become a chronic state or complications may occur. Therefore, given the important role of Toll-like receptors (TLRs) in the early response to external antigens, we surveyed the role of TLRs in otitis media. To summarize the role of TLR in otitis media, we reviewed articles on the expression of TLRs in acute otitis media (AOM), otitis media with effusion (OME), chronic otitis media (COM) with cholesteatoma, and COM without cholesteatoma. Many studies showed that TLRs 1–10 are expressed in AOM, OME, COM with cholesteatoma, and COM without cholesteatoma. TLR expression in the normal middle ear mucosa is absent or weak, but is increased in inflammatory fluid of AOM, effusion of OME, and granulation tissue and cholesteatoma of COM. In addition, TLRs show increased or decreased expression depending on the presence or absence of bacteria, recurrence of disease, tissue type, and repeated surgery. In conclusion, expression of TLRs is associated with otitis media. Inappropriate TLR expression, or delayed or absent induction, are associated with the occurrence, recurrence, chronicization, and complications of otitis media. Therefore, TLRs are very important in otitis media and closely related to its etiology.

The expression and correlation of Hsp 70 and Hsp 27 in serous middle ear effusion fluids of pediatric patients-a preliminary study

OBJECTIVES

Several cytokines and innate immune-associated molecules are present in middle ear effusions, but damage-associated molecular patterns (DAMPs) in middle ear effusion have not been studied. Therefore, we evaluated the role of heat shock proteins (Hsps) in the development of otitis media with effusion (OME).

METHODS

Serous middle ear effusions from 22 pediatric patients who were diagnosed with OME and underwent ventilation tube insertion from June 2015 to March 2017 were evaluated in our study. The levels of Hsp 90, 70, 27, IL-8, and TNF-α in effusion fluids were evaluated by enzyme-linked immunosorbent assays. The associations between the levels of these molecules and the degree of tympanic membrane inflammation were statistically evaluated. Finally, the relationships among these molecules were also evaluated.

RESULTS

Hsp 70 and Hsp 27 were detected in all middle ear effusions, but Hsp 90 was detected in only five effusion fluid samples. IL-8 was also detected in all middle ear effusions, but TNF-α was detected in only four effusion fluid samples. When we compared the degree of tympanic membrane inflammation with the levels of Hsp 70, Hsp 27, and IL-8, which were detected in all effusion fluids, we could not find statistical significance. However, Hsp 70, Hsp 27, and IL-8 were significantly associated with each other (p < 0.05).

CONCLUSIONS

Hsp 70 and Hsp 27 were expressed in middle ear effusions. Furthermore, the levels of Hsp 70 and Hsp 27 were positively correlated with each other, and were also positively associated with the neutrophil chemoattractant, IL-8. Our findings suggested that Hsp 70 and Hsp 27 might be involved in the pathophysiology of pediatric OME.

Expression of toll-like receptors 2, 4 and nuclear factor kappa B in mucosal lesions of human otitis: pattern and relationship in a clinical immunohistochemical study

OBJECTIVES

The objectives were to detect and compare the expression of toll-like receptors (TLRs) 2, 4 and nuclear factor kappa B in mucosal lesions of chronic otitis.

METHODS

Fifty-five tissue samples obtained from children and adults operated on for otitis were investigated by semiquantitative immunohistochemical methods using polyclonal antibodies for TLR 2, 4 and NFkappaB. Kruskal-Wallis, Mann-Whitney, and Kendall's tau rank correlation tests were used.

RESULTS

Stronger expression of TLR2, 4 was found in inflamed mucosa than in the control for children and adults (TLR2: H = 23.86, P < .0011; TLR4: H = 22.80, P < .00 1) (TLR2: H = 17.53, P < .001; TLR4: H = 11.99, P < .001); in cholesteatoma perimatrix compared to tubotympanic lesions in children (TLR2: H = 11.06, P = .004; TLR4: H = 10.61, P = .005) and adults (TLR2: H = 10.73, P = .013; TLR4: H = 9.65, P = .021). No differences were found in NFkB expression (H = 0.042, P = .99). Significant correlations were found for all pairs of molecules in cholesteatoma and tubotympanic mucosa of adults (TLR2, 4: P = .002, P < .001; TLR2-NfkappaB: P = .032, P = .021; TLR4-NFkB: P = .035, P = .0013), only TLR4-NFkappaB in tubotympanic otitis of children (P = .026).

CONCLUSIONS

Toll-like receptors 2,4 and NFkB mediate inflammation in cholesteatoma and mucosal lesions oftubotympanic otitis in children and adults. Significant correlations betweenall pairs of molecules in all samples were detected in adults, but only TLR4-NFkappaB in children.

Attenuated TLRs in middle ear mucosa contributes to susceptibility of chronic suppurative otitis media

The variability in the recovery of otitis media (OM) is not well understood. Recent data have shown a critical role for toll-like receptors (TLRs) in inflammatory responses to bacteria. It remains unclear whether TLRs-mediated mucosal immunity plays a role in the OM recovery. The etiology, pathological profile, expression levels of TLR2, TLR4, TLR5, TLR9 and proinflammatory cytokines were measured in human middle-ear mucosae sampled from three subject groups: non-OM group, chronic otitis-media (COM) group, and chronic suppurative otitis-media (CSOM) group. Of the 72 ears, 86.11% CSOM patients were positive for bacteria. The cellular makeup of the middle ear mucosa differs among the three groups. Mucosae from the CSOM group presented chronic inflammation or suppurative inflammation in the rudimentary stroma, mainly with infiltration of monocytes and macrophages. The mRNA and protein levels of TLR2, TLR4, and TLR5 exhibited no difference between the non-OM and COM groups but were significantly lower in the CSOM group. Conversely, there was no significant difference in the TLR9 level among the three groups. Furthermore, proinflammatory cytokines TNF-α, IL-1β, IFN-γ, IL-6 were up-regulated in the CSOM group. This study provides evidence that the variability in clinical otitis media recovery might be associated with the variability in the expression of mucosal TLRs. Reduced TLR levels in the middle-ear mucosa might cause weak host response to bacteria, persistent inflammation and susceptibility to CSOM.

Changes of histamine receptors and CC chemokines in nasal epithelial cells and fibroblasts after respiratory syncytial virus infection

BACKGROUND

Respiratory syncytial virus (RSV) is reported as the most influential factor that triggers hyperreactivity of the airway and causes asthma in infants and children. However, the mechanisms remain to be elucidated. The study evaluated the changes in the levels of four types of histamine receptor (HR) and CC chemokines, such as eotaxin and regulated on activation, normal T cell expressed and presumably secreted (RANTES), in nasal epithelial cells and fibroblasts after RSV infection.

METHODS

Nasal cavity mucosa attained from 20 patients who had undergone inferior turbinoplasty were cleaned by normal saline mixed with gentamicin. Each sample was divided in half. One-half was used for incubation of epithelial cells, and the other half was used for culturing fibroblasts. The levels of HR 1 (H1R), 2 (H2R), 3 (H3R), 4 (H4R), eotaxin, and RANTES were measured by real-time polymerase chain reaction 0, 12, and 36 hours after infection with RSV.

RESULTS

H1R was significantly increased at 12 and 36 hours compared with 0 hours in both cell types. The level of H2R was significantly increased in epithelial cells from 0 to 36 and 12 to 36 hours and in fibroblasts from 0 to 12 and 0 to 36 hours. There were significant increases of H3R level in fibroblasts from 0 to 12 and 0 to 36 hours, and of H4R in epithelial cells and fibroblasts from 0 to 12 and 0 to 36 hours. Eotaxin and RANTES were also significantly increased in both epithelial cells and fibroblasts from 0 to 12 and 0 to 36 hours.

CONCLUSION

RSV infection increases the levels of all four HRs, especially H1R and H2R, as well as the levels of eotaxin and RANTES in nasal epithelial cells and fibroblasts. These findings suggest that RSV infection might cause respiratory tract hyperreactivity by increasing the content of HRs and CC chemokines.

Expression of Toll-like receptors on peripheral blood white cells in acute otitis media

OBJECTIVE

From 10 to 15% of children suffer from recurrent acute otitis media (AOM). An association between polymorphism in TLRs and their co-receptor CD14 with otitis media proneness has been described in children. Moreover, the experiments on animal models have shown that TLRs and their signaling molecules are critical for timely resolution of bacterial otitis.

AIM

The aim of this study was to determine the expression of TLR1, TLR2 and TLR4 on lymphocytes, monocytes and granulocytes in peripheral blood in children with recurrent or persistent AOM.

METHODS

The study was performed on a group of 25 children hospitalized for recurrent AOM, failures of previous treatments and/or acute mastoiditis. The results were compared to the control group of healthy children at the same age. The expression of TLRs on peripheral blood white cells was measured by flow cytometric analysis. The results were expressed as mean fluorescence intensity (MFI). The statistical analysis was performed using the Mann-Whitney U test.

RESULTS

The highest expression of TLR was found on monocytes, the lowest on lymphocytes in both groups of children (AOM and the control one). The expression of TLR1 was the lowest and expression of TLR4 was the highest on all examined cells. The expression of all examined TLRs on monocytes was significantly higher in the AOM group.

CONCLUSIONS

Peripheral blood monocytes are characterized by increased expression of TLRs in the course of recurrent AOM.