Mucosa-associated lymphoid tissue in middle ear and Eustachian tube in children

Surfactant proteins and innate immunity of otitis media

Otitis media (OM) is the most common disease among young children and one of the most frequent reasons to visit the pediatrician. Development of OM requires nasopharyngeal colonization by a pathogen which must gain access to the tympanic cavity through the eustachian tube (ET) along with being able to overcome the defense mechanisms of the immune system and middle ear mucosa. OM can be caused by viral or bacterial infection. The three main bacterial pathogens are Streptococcus pneumoniae, nontypeable Haemophilus influenzae (NTHi), and Moraxella catarrhalis. Innate immunity is important in OM resolution as the disease occurs in very young children before the development of specific immunity. Elements of innate immunity include natural barriers and pattern recognition receptors such as Toll like receptors (TLRs), and Nod like receptors (NLRs). Surfactant proteins A (SP-A) and D (SP-D) act as pattern recognition receptors and are found in the lung and many other tissues including the ET and the middle ear where they probably function in host defense. Surfactant has a potential for use in the treatment of OM due to surface tension lowering function in the ET, and the possible immune functions of SP-D and SP-A in the middle ear and ET.

Trans-cortical vessels in the mouse temporal bulla bone are a means to recruit myeloid cells in chronic otitis media and limit peripheral leukogram changes

Chronic otitis media, inflammation of the middle ear, is a sequel to acute otitis media in ∼8% of children. Chronic otitis media with effusion is the most common cause of childhood deafness and is characterised by effusion of white blood cells into the auditory bulla cavity. Skull flat bones have trans-cortical vessels which are responsible for the majority of blood flow in and out of the bone. In experimental models of stroke and aseptic meningitis there is preferential recruitment of myeloid cells (neutrophils and monocytes) from the marrow in skull flat bones. We report trans-cortical vessels in the mouse temporal bone connect to the bulla mucosal vasculature and potentially represent a means to recruit myeloid cells directly into the inflamed bulla. The mutant mouse strains Junbo (Mecom^Jbo/+) and Jeff (Fbxo11^Jf/+) develop chronic otitis spontaneously; Mecom^Jbo/+ mice have highly cellular neutrophil (90%) rich bulla exudates whereas Fbxo11^Jf/+ mice have low cellularity serous effusions (5% neutrophils) indicating differing demand for neutrophil recruitment. However we found peripheral leukograms of Mecom^Jbo/+ and Fbxo11^Jf/+ mice are similar to their respective wild-type littermate controls with healthy bullae and infer preferential mobilization of myeloid cells from temporal bulla bone marrow may mitigate the need for a systemic inflammatory reaction. The cytokines, chemokines and haematopoietic factors found in the inflamed bulla represent candidate signalling molecules for myeloid cell mobilization from temporal bone marrow. The density of white blood cells in the bulla cavity is positively correlated with extent of mucosal thickening in Mecom^Jbo/+, Fbxo11^Jf/+, and Eda^Ta mice and is accompanied by changes in epithelial populations and bone remodelling. In Mecom^Jbo/+ mice there was a positive correlation between bulla cavity WBC numbers and total bacterial load. The degree of inflammation varies between contralateral bullae and between mutant mice of different ages suggesting inflammation may wax and wane and may be re-initiated by a new wave of bacterial infection. Clearance of white blood cells and inflammatory stimuli from the bulla cavity is impaired and this may create a pro-inflammatory feedback loop which further exacerbates otitis media and delays its resolution.

Mucosa-Associated Lymphoid Tissue and Tertiary Lymphoid Structures of the Eye and Ear in Laboratory Animals

Mucosa-associated lymphoid tissue (MALT) of special senses is poorly described and can be confused with nonspecific mononuclear cell infiltrates and tertiary lymphoid structures (TLS). In the eye, MALT consists mostly of conjunctiva-associated lymphoid tissue (CALT) and lacrimal drainage-associated lymphoid tissue (LDALT). In humans, CALT and LDALT are important components of the normal eye-associated lymphoid tissue (EALT), but EALT is less frequently described in ocular tissues of animals. The EALT are acquired postnatally in preferential mucosal sites, expand with antigenic exposure, form well-developed lymphoid follicles, and are reported to senesce. Lymphoid follicles that are induced concurrently with chronic inflammation are more appropriately considered TLS but must be differentiated from inflammation in MALT. Less understood is the etiology for formation of lymphoid tissue aggregates in the ciliary body, limbus, or choroid of healthy eyes in animals and humans. In the healthy eustachian tube and middle ear of animals and humans, MALT may be present but is infrequently described. Concurrent with otitis media, lymphoid follicles in the eustachian tube are probably expanded MALT, but lymphoid follicles in the middle ear may be TLS. The purpose of this comparative review is to familiarize toxicologic pathologists with MALT in the special senses and to provide considerations for differentiating and reporting eye and ear MALT from immune or inflammatory cell infiltrates or inflammation in nonclinical studies, and the circumstances for reporting TLS in compartments of the eye and ear.

Regulatory T lymphocytes are associated with increased nasopharyngeal colonization in children

OBJECTIVES

Regulatory T lymphocytes (T_reg) have been linked to survival of commensal bacteria at mucosal sites, but their presence and role in chronic otitis media (COM) and their response to otopathogens has not been evaluated previously. We investigated the association between T_reg lymphocytes and otopathogens in COM prone and non-COM prone children.

METHODS

Forty children, 2-7 years of age, scheduled for adenoidectomy were enrolled into COM (n = 20) or non-COM (n = 20) groups. Adenoid biopsy and nasopharyngeal aspirate bacteriology were assessed by conventional culture techniques. Peripheral blood and adenoid lymphocytes were stained with viability stain, monoclonal anti-CD19, anti-CD3, anti-CD4, anti-CD8, anti-CD25 and anti-CD127. Cells were stained intracellularly with monoclonal anti-FoxP3 and then quantified by flow cytometry.

RESULTS

Children with nasopharyngeal otopathogen-positive culture had significantly more circulating CD3⁺CD4⁺FoxP3⁺CD25^hi+CD127^lo+ lymphocytes (M = 4.4%) compared to culture-negative children (M = 3.1%, p = 0.005). Circulating CD19⁺ lymphocytes were significantly increased in children with positive Moraxella catarrhalis nasopharyngeal culture (M = 12.4%) compared to culture-negative children (M = 8.6%, p = 0.006). Adenoid-derived lymphocytes were not significantly different in children with any positive nasopharyngeal culture compared to negative culture. Lymphocyte subsets were not significantly different between COM and non-COM prone children.

CONCLUSION

Clinically-detectable otopathogen nasopharyngeal culture is positively associated with T_reg lymphocytes, potentially inducing suppressive effector responses to promote colonization and infection chronicity. This finding supports further investigation of T_reg lymphocyte activity and influence on upper airway colonization of young children.

Primary T-cell lymphoblastic lymphoma in the middle ear

T-cell lymphoblastic lymphoma (T-LBL) is a highly aggressive lymphoma characterized by precursor T-cell malignancy and lymphadenopathy or mediastinal involvement. We present the case of an 11-year-old boy with a diagnosis of middle ear T-LBL, which manifested as a headache, hearing loss and peripheral facial paralysis. The child was given intensive chemotherapy and had a complete response. To our knowledge, this is the first case reported in the literature of T-LBL originating in the middle ear. This case aims to help clinicians to be vigilant about the possibility of primary lesions at atypical sites in some special diseases.

Middle Ear and Eustachian Tube Mucosal Immunology

Mucosal immune responses within the middle ear and eustachian tube generally provide an effective and efficient response to the presence of microbial pathogens, with approximately 80% of clinically recognizable middle ear infections resolved within 7 days. Particularly for young children aged less than 3 years of age, the proximity and direct connection of the middle ear, via the eustachian tube, to the nasopharynx provide increased risk of commensal bacteria and upper respiratory tract viruses infecting the middle ear. Mucosal immunological defense in the middle ear and eustachian tube utilizes a number of mechanisms, including physicochemical barriers of mucus and the mucosal epithelial cells and innate immune responses such as inflammation, cellular infiltration, effusion, and antimicrobial protein secretions, in addition to adaptive host immune responses. Recent advances in otopathogen recognition via microbial pattern recognition receptors and elucidation of complex signaling cascades have improved understanding of the coordination and regulation of the middle ear mucosal response. These advances support vaccine development aiming to reduce the risk of otitis media in children.

Do mucosal folds in the eustachian tube function as microturbinates?

OBJECTIVES/HYPOTHESIS

Mucosal folds in the eustachian tube (ET) may function as microturbinates and provide protection and clearance.

STUDY DESIGN

Descriptive study.

METHODS

Nineteen whole-mount temporal bone ET specimens (nine pediatric and 10 adult) were evaluated in the present study. Five specific localizations for each case were selected. The cartilaginous segment of the ET was divided vertically and the length of mucosal surfaces and the number of mucosal folds of anterior and posterior walls on the histological sections were analyzed with MetaMorph 7.5.2.0 software.

RESULTS

The length of the mucosal surface of the posterior wall of the ET was longer than the anterior wall (P < .05). In pediatric specimens, the posterior wall had more mucosal folds than adult specimens (P < .05).

CONCLUSIONS

Microturbinates in the posterior wall of the ET may provide important protection and clearance functions for children and play a role in the pathogenesis of eustachian tube dysfunction

Auditory function and hearing loss in children and adults with Williams syndrome: cochlear impairment in individuals with otherwise normal hearing

Hearing loss is common in school-age individuals with Williams syndrome (WS) and extensive in adults. Prior studies with relatively small sample sizes suggest that hearing loss in WS has an early onset and may be progressive, yet the auditory phenotype and the scope of the hearing loss have not been adequately characterized. We used standard audiometric tools: Otoscopy, tympanometry, air-conduction (bone conduction when available) behavioral testing, and distortion product otoacoustic emissions (DPOAEs) to measure hearing sensitivity and outer hair cell function. We tested 81 individuals with WS aged 5.33-59.50 years. Sixty-three percent of the school-age and 92% of the adult participants had mild to moderately-severe hearing loss. The hearing loss in at least 50% was sensorineural. DPOAE testing corroborated behavioral results. Strikingly, 12 of 14 participants with hearing within normal limits bilaterally had 4,000-Hz DPOAE input/output (DPOAE IO) functions indicative of outer hair cell damage and impaired cochlear compression. Our results indicate that hearing loss is very common in WS. Furthermore, individuals with WS who have "normal" hearing as defined by behavioral thresholds may actually have sub-clinical impairments or undetected cochlear pathology. Our findings suggest outer hair cell dysfunction in otherwise normal hearing individuals. The DPOAE IO in this same group revealed growth functions typically seen in groups with noise-induced damage. Given this pattern of findings, individuals with WS may be at increased risk of noise-induced hearing loss. Recommendations regarding audiological testing for individuals with WS and accommodations for these individuals in both academic and nonacademic settings are provided.

Ophthalmic lymphoma: epidemiology and pathogenesis

With a lifetime risk of 1% and 700 new cases per year, Non-Hodgkin lymphoma (NHL) is the seventh most frequent type of cancer in Denmark. The incidence of NHL has increased considerably in Western countries over the last decades; consequently, NHL is an increasing clinical problem. Ophthalmic lymphoma, (lymphoma localized in the ocular region, i.e. eyelid, conjunctiva, lacrimal sac, lacrimal gland, orbit, or intraocularly) is relatively uncommon, accounting for 5%-10% of all extranodal lymphomas. It is, however, the most common orbital malignancy. The purpose of this thesis was to review specimens from all Danish patients with a diagnosis of ophthalmic lymphoma during the period 1980-2005, in order to determine the distribution of lymphoma subtypes, and the incidence- and time trends in incidence for ophthalmic lymphoma. Furthermore, an extended analysis of the most frequent subtype, extranodal marginal zone lymphoma (MALT lymphoma), was done to analyse clinical factors and cytogenetic changes with influence on prognosis. A total of 228 Danish patients with a biopsy-reviewed verified diagnosis of ocular adnexal-, orbital-, or intraocular lymphoma were identified. We found that more than 50% of orbital- and ocular adnexal lymphomas were of the MALT lymphoma subtype, whereas diffuse large B-cell lymphoma (DLBCL) predominated intraocularly (Sjo et al. 2008a). Furthermore, lymphoma arising in the lacrimal sac was surprisingly predominantly DLBCL (Sjo et al. 2006). Incidence rates were highly dependent on patient age. There was an increase in incidence rates for the whole population from 1980 to 2005, corresponding to an annual average increase of 3.4% (Sjo et al. 2008a). MALT lymphoma arising in the ocular region was found in 116 patients (Sjo et al. 2008b). One third of patients had a relapse or progression of disease after initial therapy and relapses were frequently found at extra-ocular sites. Overall survival, however, was not significantly poorer for patients with relapse. Furthermore, we found that the frequency of translocations involving the MALT1- and IGH-gene loci is low in ocular region MALT lymphoma (2 of 42, 5%), but may predict increased risk of relapse (Sjo et al. 2008b). In conclusion the incidence of ophthalmic lymphoma is increasing at a high rate in Denmark. Ophthalmic lymphoma consists primarily of MALT lymphoma. The molecular pathogenesis of MALT lymphoma arising in the ocular region rarely involves translocations in the MALT1- and IGH-gene loci.

Functions of tonsils in the mucosal immune system of the upper respiratory tract using a novel animal model, Suncus murinus

CONCLUSION

The human palatine tonsils and the nasopharyngeal tonsil were considered the defense mechanism against ingested or inhaled foreign pathogens. The current findings suggest that the tubal tonsils possess abilities of active transportation of foreign antigens, and will act as inductive and effector sites in the mucosal immune system. Our results also indicated a significant difference in roles of immune responses among individual tonsillar organs, suggesting functional sub-compartmentalization.

OBJECTIVES

To address the function of tonsils in inducing local immune responses, we evaluated the antigen uptake of tubal tonsils and the induction of specific immune responses in a small laboratory animal with both tubal and palatine tonsils, i.e. Suncus murinus.

MATERIALS AND METHODS

S. murinus were injected with 2 x 10(6) CFU of FITC-labeled Staphylococcus aureus via the right tympanic cavity. The distribution of the FITC-labeled S. aureus was examined under a fluorescent microscope. S. murinus were also immunized with 100 microg of ovalbumin (OVA) mixed with 2 microg of cholera toxin (CT) via the right external ear meatus every 2 days for 2 weeks. One week after the final immunization, sera, pairs of tubal and palatine tonsils, and the neck lymph nodes were obtained to evaluate the induction of specific immune responses.

RESULTS

The FITC-labeled S. aureus particles were detected in tubal tonsils and also in cervical lymph nodes. Total IgA-producing cells and OVA-specific antibody-producing cells were identified in the immunized tubal tonsils. Trans-external ear meatus immunization of tubal tonsils also evoked systemic antibody responses.

Eustachian tube possesses immunological characteristics as a mucosal effector site and responds to P6 outer membrane protein of nontypeable Haemophilus influenzae

The eustachian tube (ET) plays an important role in the pathogenesis of otitis media (OM). To better understand its biology and to develop a nasal vaccine for preventing OM, mucosal lymphocytes in the ET were analyzed, and the ET's immunological function was investigated. Mononuclear cells were isolated from murine ET, and lymphocyte subsets were analyzed by flow cytometry. Antibody-producing cells were determined by enzyme-linked immunospot assay. The expression of cytokine mRNA in ET CD4(+) T cells was determined by RT-PCR. Results in naive mice showed that the ET contained many immunocompetent cells, including a relative large number of IgA-producing cells and Th2 cytokine-expressing T cells. Next, we investigated antigen-specific immune responses in the ET. Mice were immunized intranasally with the P6 outer membrane of nontypeable Haemophilus influenzae (NTHi) and cholera toxin (CT), and P6-specific immune responses in the ET were examined. P6-specific IgA producing cells markedly increased in the ET. Moreover, in vitro stimulation with P6 of purified CD4(+) T cells from immunized mice resulted in the proliferation of CD4(+) T cells that expressed Th2 cytokine mRNA. These results indicate that the ET might be characterized as a mucosal effector site and that antigen-specific IgA and Th2 immune responses could be induced in the ET by intranasal immunization. These findings suggest that the ET might be a key immunological organ in the pathogenesis of OM, and in the development of a nasal vaccine.

Cellular proliferation of mucosa-associated lymphoid tissue with otitis media: a preliminary study

Histopathologic and immunohistochemical analyses were used to investigate the cellular proliferation of mucosa-associated lymphoid tissue (MALT) in human temporal bones with and without evidence of otitis media (OM). Anti-proliferating cell nuclear antigen (PCNA) antibody (clone PC10) was applied after the antigen retrieval procedure. Positive PCNA expression was observed in temporal bones that had been stored for 10 to 31 years in 80% ethanol. In specimens with purulent OM, the MALT had faint germinal centers (GCs). Positive PCNA expression in the MALT was moderate and scattered. In specimens with mucous OM, the MALT had complete GCs. Positive PCNA expression in the MALT was moderate to strong, and the distribution of PCNA-positive cells was associated predominantly in the GCs, the mucosal epithelial layer, and/or the subepithelial layer. In specimens with serous OM, the MALT also had complete GCs. However, the PCNA expression was weak and scattered, and appeared to be similar to that of the MALT in the temporal bones without OM. These results indicate that the cellular proliferation of MALT in the temporal bone might reflect the activity that produces secretory IgA against invasion of foreign antigens. However, further studies are needed to elucidate whether the PCNA expression within MALT in the eustachian tube and middle ear is associated with a mucosal immune response to inflammation as in OM.

Mucosa-associated lymphoid tissue in middle ear and eustachian tube

The presence of mucosa-associated lymphoid tissue (MALT) was investigated histopathologically in every 20th section from 99 vertically cut, celloidin-embedded temporal bone-eustachian tube (ET) specimens. Among specimens from infants and children between 1 month and 7 years of age, MALT was found in 22 of 44 (50%). However, in 26 adults over 18 years of age, MALT was found in only 2 specimens (7.7%), a significantly lower incidence than that in infants and children. Moreover, MALT did not appear in any of the 21 neonates under the age of 1 month. All 99 specimens were classified into 2 groups: 41 specimens with otitis media (OM) and 58 specimens without OM. The presence of MALT was significantly higher in specimens with OM (43.9%) than in specimens without OM (13.8%). Mucosa-associated lymphoid tissue was found in the ET, middle ear, and mastoid process in 18 specimens (43.9%). 5 specimens (12.2%), and 1 specimen (2.4%) with OM, respectively, and in 8 (13.8%), 0, and 0 specimens without OM. In regard to the distribution of MALT, it occurred more frequently in the pharyngeal half of the cartilaginous portion of the ET than in the rest of the ET, middle ear, and mastoid; the presence was significantly greater in the inferior half of the cartilaginous portion of the ET than in the superior half. Inflammatory cell infiltration in the cartilaginous and bony portions of the ET was significantly greater in specimens with OM than in specimens without OM with no MALT. However, even in some specimens without OM, inflammatory cells were found in the ET, particularly in the pharyngeal half of the cartilaginous portion of the ET. These findings suggest that MALT has a close relationship to OM and that it may be a local response to repeated infection.

Cell biology of tubotympanum in relation to pathogenesis of otitis media - a review

The sterility of the eustachian tube and tympanic cavity of normal individuals is maintained not only by the adaptive immune system, but also by the mucociliary system and the antimicrobial molecules of innate immunity. Mucin production and periciliary fluid homeostasis are essential for normal mucociliary function and dysfunction of this system is an important risk factor for otitis media. The secreted antimicrobial molecules of the tubotympanum include lysozyme, lactoferrin, beta defensins, and the surfactant proteins A and D (SP-A, SP-D). Defects in the expression or regulation of these molecules may also be the major risk factor for otitis media.

Cellular distribution of mucosa-associated lymphoid tissue with otitis media in children

This study examined mucosa-associated lymphoid tissue (MALT) in the eustachian tube (ET), middle ear (ME), and mastoid antrum (MA) in 163 celloidin-embedded temporal bones from children with or without otitis media. Otitis media was defined by the presence of histopathologically identified inflammatory cell infiltration in the mucosa or cavity of the ME. We found MALT in the ET in 30 cases (46.2%), in the ME in 19 cases (29.2%), and in the MA in 4 cases (6.2%) out of 65 cases of otitis media, and in the ET in 7 (7.1%), in the ME in 0, and in the MA in 0 out of 98 specimens without otitis media. No MALT appeared in any children under the age of 1 month. Immunohistochemical methods were used to investigate MALT in 12 horizontally cut temporal bones with OM. The follicular area contained OPD4-positive (helper-inducer T) cells and a few CD8-positive (cytotoxic and suppressor T) cells, whereas the parafollicular area contained OPD4-positive and CD8-positive T cells. CD57-positive (natural killer) cells were confined to the germinal center. CD30-positive (activated T and B) cells were observed throughout the follicles. A few CD15-positive (granulocyte, monocyte) cells were found in the follicles. Histopathologic and immunohistochemical findings were indistinguishable for MALT in the ET, ME, and MA. Our results suggest that MALT may be a mechanism for producing a rapid and massive local immune reaction to repeated bacterial infections via the ET.