Effect of Urban Particulate Matter on Vocal Fold Fibrosis through the MAPK/NF-κB Signaling Pathway

Particulate matter (PM) is an environmental exposure factor that adversely affects human health. PM is a risk factor for various diseases. However, the mechanism by which PM affects the vocal folds (VF) has not yet been evaluated. Thus, we investigated the cytotoxic effects of PM on human vocal fold fibroblasts (hVFF) and the underlying signaling pathways. hVFF were isolated from human VF. The effect of PM on hVFF, and the underlying mechanism, were analyzed using Western blot, quantitative real-time polymerase chain reaction, and flow cytometry. In addition, a histological evaluation was performed in animal experiments. Cell proliferation decreased after the PM treatment. PM increased the expression of interleukin (IL)-6 and IL-1β. The generation of reactive oxygen species (ROS) in PM-treated hVFF and subsequent activation of the mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) pathways were confirmed. Furthermore, PM increased the expression of fibrosis-related markers and induced the accumulation of collagen in the extracellular matrix. As a result, PM exposure significantly enhances the inflammatory response on VF through the ROS-mediated activation of the MAPK and NF-κB signaling pathways. In addition, PM promotes differentiation into myofibroblasts and induces fibrosis. These results suggest that PM triggers an inflammatory reaction through ROS production and causes VF fibrosis.

Chloroquine Treatment Suppresses Mucosal Inflammation in a Mouse Model of Eosinophilic Chronic Rhinosinusitis

PURPOSE

The Toll-like receptor 9 (TLR9) signaling pathway is involved in the pathogenesis of chronic rhinosinusitis (CRS) with nasal polyposis. The aim of this study was to assess the therapeutic potential of the TLR9 pathway inhibitor chloroquine in CRS mice.

METHODS

The expression of type I interferons (IFNs) in human CRS tissues was evaluated using quantitative polymerase chain reaction (qPCR), western blotting, and immunofluorescence. Mice were divided into 4 treatment groups: the control, nasal polyp (NP), chloroquine treatment (NP + Chlq), and dexamethasone treatment (NP + Dexa) groups. The effects of chloroquine on polyp formation and mucosal inflammation were examined by hematoxylin and eosin staining. The expression levels of type I IFN, B-cell activating factor (BAFF), TLR9, high mobility group box 1 (HMGB1), and proinflammatory cytokine expression levels were assessed using qPCR, western blot, or enzyme-linked immunosorbent assay.

RESULTS

IFN-α and IFN-β mRNA levels were significantly higher in patients with eosinophilic NPs (EPs) than in healthy individuals or non-EP patients. The polyp score, epithelial thickness, mucosal thickness, and the number of eosinophils in nasal mucosa were significantly higher in the NP group compared with the control, NP + Chlq, and NP + Dexa groups. NP + Chlq or NP + Dexa significantly suppressed the induction of type I IFN and BAFF expression in the NP group; these treatments also significantly suppressed the induction of TLR9, HMGB1, interferon regulatory factors, interleukin (IL)-6, IL-1β, tumor necrosis factor-α, and Th cytokine expression in the NP group. The secreted levels of anti-dsDNA Immunoglobulin G (IgG) were significantly higher in the NP group than in the control, NP + Chlq, and NP + Dexa groups. There were significant positive correlations between BAFF and mRNA levels of IFN-α/β/the protein levels of anti-dsDNA IgG.

CONCLUSIONS

Chloroquine may be used for the treatment of patients with eosinophilic CRS.

Altered Mitochondrial Functions and Morphologies in Epithelial Cells Are Associated With Pathogenesis of Chronic Rhinosinusitis With Nasal Polyps

Purpose

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a complex inflammatory disease of the nasal and paranasal sinus mucosa. The disease is associated with mitochondrial dysfunction, structural changes in the mitochondria, and reactive oxygen species (ROS) generation. This study investigated whether there are functional and morphological changes in the mitochondria in the epithelial cells of nasal polyps (NPs) and Staphylococcus aureus enterotoxin B (SEB)-stimulated nasal epithelial cells.

Methods

In all, 30 patients with CRSwNP and 15 healthy subjects were enrolled. Mitochondrial ROS (mtROS) and changes in mitochondrial functions and structures were investigated in the uncinate tissue (UT) of healthy controls, the UT or NPs of CRSwNP patients, and human nasal epithelial cells with or without SEB stimulation.

Results

Oxidative phosphorylation complexes showed various responses following SEB stimulation in the nasal epithelial cells, and their expressions were significantly higher in the NPs of patients with CRSwNP than in the UT of controls. Generation of mtROS was increased following SEB exposure in nasal epithelial cells and was reduced by pretreatment with MitoTEMPO, which is used as an mtROS scavenger. In the tissues, mtROS was significantly increased in the NPs of CRSwNP patients compared to the UT of controls or CRSwNP patients. The expressions of fusion- and fission-related molecules were also significantly higher in SEB-exposed nasal epithelial cells than in non-exposed cells. In tissues, the expression of fission (fission mediator protein 1)- and fusion (membrane and mitofusin-1, and optic atrophy protein 1)-related molecules was significantly higher in the NPs of CRSwNP patients than in UT of controls or CRSwNP patients. Transmission electron microscopy revealed elongated mitochondria in SEB-exposed nasal epithelial cells and epithelial cells of NPs.

Conclusions

Production of mtROS, disrupted mitochondrial function, and structural changes in nasal epithelial cells might be involved in the pathogenesis of CRSwNP.

Role of Toll-like receptor 9 signaling on activation of nasal polyp-derived fibroblasts and its association with nasal polypogenesis

BACKGROUND

Nasal polyposis is characterized by persistent inflammation and remodeling in sinonasal mucosa. Toll-like receptor 9 (TLR9) is a DNA receptor of the innate immune system that plays a pivotal role in fibrosis and inflammatory responses. The aim of this study is to explore the expression, activity, and potential pathogenic role of TLR9 signaling in tissue remodeling in nasal polyp-derived fibroblasts (NPDFs).

METHODS

Fibrotic and inflammatory responses elicited by type A CpG oligonucleotides were examined in the NPDFs by a combination of real-time quantitative polymerase chain reaction, Western blot analysis, enzyme-linked immunosorbent assay, and immunofluorescence staining. For these experiments, the NPDFs were stimulated with different TLR9 agonists (CpG A and B) and blocked with inhibitors (MyD88 inhibitor and chloroquine).

RESULTS

TLR9 expression was significantly higher in nasal polyposis (NP) tissues compared to control or chronic rhinosinusitis (CRS) mucosa. In the NPDFs, TLR9 showed intracellular localization and expression of TLR9 was increased after treatment with CpG A. CpG A increased production of α-smooth muscle actin (α-SMA), fibronectin, and matrix metalloproteinases (MMPs) (MMP1, MMP2, and MMP9) in the NPDFs, while MyD88 inhibitor and chloroquine, which are known to block the TLR9 signaling pathway, inhibited their production. CpG A also produced type I interferons (IFN-α and IFN-β), which were inhibited by MyD88 inhibitor.

CONCLUSION

Our data indicates that CpG A-induced fibroblast activation and cytokine production were mediated via TLR9 stimulation in NPDFs. Disrupting this process with an inhibitor targeting TLR9 or its downstream signaling pathways could represent a novel approach to CRS with NP (CRSwNP) therapy.

LAMB3 mediates metastatic tumor behavior in papillary thyroid cancer by regulating c-MET/Akt signals

Laminin subunit beta-3 (LAMB3) encodes one of the three subunits of LM-332, a protein of the extracellular matrix secreted by cultured human keratinocytes. While LAMB3 is involved in the invasive and metastatic abilities of several tumor types, including those found in the colon, pancreas, lung, cervix, stomach, and prostate, its mechanism of action in thyroid cancer has not been investigated previously. Our results show that LAMB3 is up-regulated in papillary thyroid cancer, and that its suppression reduces cell migration/invasion via down-regulation of epithelial‒mesenchymal transition-associated proteins (N-cadherin, vimentin, slug) and inhibition of matrix metalloproteinase 9. LAMB3 suppression also significantly decreases Akt phosphorylation and inhibits the transcription of c-MET, reducing its activation. These results suggest that LAMB3 leads to tumor invasion via Akt activation induced by the HGF/c-MET axis in papillary thyroid cancer cells. Our findings reveal a novel mechanism of action for LAMB3 in papillary thyroid cancer cells.

The effects of uvulopalatal flap operation on speech nasalance and the acoustic parameters of the final nasal consonants

OBJECTIVE

The acoustic characteristics of voice are determined by the source of the sound and shape of the vocal tract. Various anatomical changes after uvulopalatal flap (UPF) operation can change nasalance and/or other voice characteristics. Our aim was to explore the possible effects of UPF creation on speech nasalance and the resonatory features of the final nasal consonants, and thus voice characteristics.

METHODS

A total of 30 patients (26 males, 4 females) with obstructive sleep apnea who underwent UPF operation were recruited. A Nasometer II 3.4 instrument was used to assess nasalance pre- and post-operatively; the patients read standard Korean passages and the readings were recorded in Computer Speech Laboratory for later spectral analysis. Praat software was used to identify frequency bands affecting perioperative nasalance scores. Minima, maxima, and slopes were analyzed.

RESULTS

We found no significant correlation between nasalance scores (any passage) and the respiratory distress index or body mass index. No significant perioperative change in any nasalance score. The moment variations in the final consonants /m/ and /n/ did not change significantly postoperatively. However, the postoperative moment variation of the final consonant /ng/ differed significantly in the third formant (F3) and second bandwidth (BW2).

CONCLUSION

Few significant changes in nasal resonance speech quality were apparent after UPF operation. However, a postoperative acoustic change in the final sound /ng/ may be sustained. Patients may be preoperatively advised that the risk of voice change is very low, but not absent.

Effect of Topical Mitomycin C on the Healing of Surgical and Laser Wounds: A Hint on Clinical Application

OBJECTIVES: Mitomycin C (MMC) is used in otolaryngological surgery to reduce complications from postoperative scarring. However, the effects of MMC on wound healing at different doses and on different wound types have not been fully described. The aim of this study was to evaluate the effects of topical MMC at 2 different doses on the healing of surgical and laser wounds.

STUDY DESIGN AND SETTING: This was a randomized study using 20 rabbits. Six full-thickness wounds were made by excision or laser vaporization on the flank skin. The wounds were randomly treated by topical MMC of 0.4 or 1.0 mg/mL or saline for 5 minutes.

RESULTS: Re-epithelialization and contraction of the original wounds were significantly delayed by the use of MMC ( P < 0.01). The delayed healing effect of MMC was more prominent in the laser wounds than in the excision wounds. MMC inhibited collagen deposition and fibroblast proliferation of wounds on histological analysis. The 2 different concentrations of MMC showed no difference in gross or histological wound healing characteristics.

CONCLUSION: Our results showed that MMC delays the healing of wounds as a result of the inhibition of fibrosis, especially for laser wounds.

Benefits and risks of mitomycin use in the traumatized tracheal mucosa

Objective

To investigate the efficacy and early complications of mitomycin C (MMC) in tracheal wound models.

Study Design and Setting

Rabbits (N = 60) were randomized to undergo mucosal injuries to the upper and lower trachea including anterior 120° full thickness (group A, n = 20), anterior 120° partial thickness (group B, 20), and circumferential partial thickness (group C, 20). In each rabbit, the wounds were separately treated with MMC 1.0 mg/mL or saline, and the animals were sacrificed after three weeks.

Results

Twenty-seven of the 60 animals experienced early death because of tracheal rupture or airway obstruction caused by unresolved scabs on the preinjured tracheal mucosa; the incidence of early death was higher in groups A and C than in group B. In each group, the degree of tracheal stenosis was comparable in wounds treated with MMC and saline.

Conclusion

These findings suggest that topical MMC has no benefit when used to prevent tracheal stenosis. Acute airway obstruction may occur in MMC-treated rabbits with tracheal wounds.

Effect of furanone on experimentally induced Pseudomonas aeruginosa biofilm formation: in vitro study

OBJECTIVE

The purpose of this study was to evaluate the effect of furanone as a quorum sensing inhibitor with an antibiotic agent on experimentally induced Pseudomonas aeruginosa biofilm formation in an in vitro model.

MATERIALS AND METHODS

Bacterial cultures on agar plates and induction of biofilm formations were done in four different conditions; P. aeruginosa only (group 1), P. aeruginosa+ciprofloxacin (group 2), P. aeruginosa+furanone (group 3), and P. aeruginosa+furanone+ciprofloxacin (group 4). After biofilm formation on a silicone tympanostomy tube with P. aeruginosa was established, they were treated with ciprofloxacin, furanone, and ciprofloxacin with furanone respectively. All agar plates were processed for colony counts 1 day after incubation, and silicone tympanostomy tubes were observed using scanning electron microscopy 2 days after incubation. Any changes visualized on the biofilm lining the silicone tympanostomy tubes after treatment initiation were evaluated again 2 days after each treatment.

RESULTS

There was no bacterial growth on the agar plate in group 4 compared to other groups and the formations of a biofilm on the surface of silicone tympanostomy tubes in group 4 were devoid. Little change to the original biofilm overlying the silicone tympanostomy tubes after each treatment was noted.

CONCLUSION

This study demonstrates that furanone may have a role as a QSI and can be helpful in preventing biofilm formation with ciprofloxacin in experimentally induced P. aeruginosa biofilms based on an in vitro model.

Expression of matrix metalloproteinase-12 is correlated with extracapsular spread of tumor from nodes with metastasis in head and neck squamous cell carcinoma

Matrix metalloproteinases (MMPs) play an important role in tumor invasiveness and metastasis. The aim of this study was to investigate the expression pattern of MMPs in the primary tumor of head and neck squamous cell carcinomas (HNSCC) with cervical node metastasis and to correlate the expression of MMP in the primary tumor with the presence of extracapsular spread (ECS) in nodes with metastasis. A retrospective study was conducted. Paraffin blocks were obtained from 40 HNSCC patients with cervical node metastasis who underwent surgery as an initial treatment between 2004 and 2011. Expressions of MMP-2, MMP-3, MMP-12, and MMP-14 were investigated immunohistochemically. MMP-2, MMP-3, MMP-12, and MMP-14 were expressed in 27, 47.5, 55, and 57.5 % of cases, respectively. MMP-12 expression was found to be significantly associated with ECS and correlated with nodal metastasis (p = 0.024, 0.011). No relation was found between MMP expression and survival. MMP-12 expressed in the primary tumor is a molecular marker that may be useful for predicting ECS in HNSCC patients with metastatic nodal disease.

Altered expression of E-cadherin and &#946;-catenin in malignant transformation of sinonasal inverted papillomas

BACKGROUND

E-cadherin and &amp;#946;-catenin are molecules that mediate cell-cell adhesion in normal epithelium. Aberrant expression of these adhesion molecules results in the loss of intercellular adhesion, with possible cell transformation and tumour progression. We determined the role of E-cadherin and &amp;#946;-catenin in the pathogenesis of sinonasal inverted papilloma (IP) and its malignant transformation.

METHODS

We determined the expression of E-cadherin and &amp;#946;-catenin by immunohistochemistry in paraffin-embedded tissue of 21 subjects with nasal polyps, 56 with IPs, 7 IPs with dysplasia and 18 IPs with squamous cell carcinoma (SCC). The clinicopathological variables of the IPs with SCC correlated with the degree of expression of E-cadherin and &amp;#946;-catenin.

RESULTS

The degree of expression of E-cadherin and &amp;#946;-catenin in the cell membrane was significantly lower in IPs with SCC than in nasal polyps and IPs. The degree of expression of &amp;#946;-catenin was significantly lower in IPs with SCC with a malignant proportion &gt; 50% compared to a malignant proportion &amp;#8804; 50%. However, there was no significant association between the degree of expression of E-cadherin and &amp;#946;-catenin and clinicopathological variables, such as age, gender, T stage, tumour differentiation, or SCC type (metachronous vs. synchronous). In addition, there was no significant relationship between recurrence or survival rate in IPs with SCC and the degree of expression of E-cadherin or &amp;#946;-catenin in the cell membrane or nuclear &amp;#946;-catenin.

CONCLUSION

Decreased expression of E-cadherin and &amp;#946;-catenin in the cell membrane may be associated with carcinogenesis of IPs and help predict malignant transformation in sinonasal IPs.

Is there any synergic effect for coadministration of mitomycin C and halofuginone on the skin wound healing?

OBJECTIVE

This study compared the potencies of the antifibrotic agents mitomycin C (MMC) and halofuginone (HFN) and investigated whether coadministration of these agents produces synergic effects in an animal skin wound model.

SUBJECTS AND METHODS

Twenty male Sprague-Dawley rats were used for this study. After a full-thickness excisional wound was made on the dorsum of each rat, each rat was treated with topical mitomycin, intraperitoneal HFN, or both. Wound surface areas were measured over time, and histologic analysis was performed after wounds healed completely.

RESULTS

The groups treated with MMC alone, HFN alone, and a combination of the two all exhibited delayed wound healing compared with the untreated group. Histologically, fibrosis and matrix metalloproteinase-2 expression were significantly inhibited in the treated groups. However, there were no gross or histologic differences between the MMC-treated group, the HFN-treated group, and the combination-treatment group.

CONCLUSIONS

Both MMC and HFN inhibited excessive fibrosis. However, there was no significant difference in the antifibrotic effects of MMC and HFN on surgically induced skin wounds. Moreover, combination treatment with both MMC and HFN failed to confer an additional antifibrotic effect on skin wounds when compared with treatment with MMC or HFN alone.

Development of guideline for rating the physical impairment of otolaryngologic field

We develop a guideline for rating the physical impairment of otolaryngologic fields. Assessment of hearing disturbance and tinnitus required physical examination, pure tone audiometry, speech audiometry, impedance audiometry, brainstem evoked response audiometry, Bekesy audiometry, otoacoustic emission test, and imaging examination. History taking, physical examination, and radiological examination for the vestibular organ and brain, righting reflex test, electronystagmography, and caloric test are taken for evaluation of balance disorder. Olfactory function tests include University of Pennsylvania Smell Identification test, Connecticut Chemosensory Clinical Research Center test, T and T olfactometry and Korean Version of Sniffin's Sticks test. Medical history and physical examination is mandatory to evaluatezseverity of respiration difficulty. Examinations include flexible fiberoptic nasopharyngoscope, bronchoscopy, simple soft-tissue radiography films of upper airway and high resolution computed tomography. Evaluation of mastication and swallowing are history taking, physical examination, examination for upper jaw, lower jaw, and temporomandibular joint, dental examination and radiological studies. Endoscopy and esophagography are also needed. Voice disorder is evaluated based on physical examination, oral pharynx and larynx endoscopy, larynx stroboscopy, hearing assessment, laryngeal electromyography, sound analysis test, aerodynamic test, electroglottography, and radiologic examination. Articulation disorder is assessed by picture consonant articulation test. These are position articulation test, Lee-Kim Korean articulation picture and speech intelligibility assessment.

Is central neck dissection necessary for the treatment of lateral cervical nodal recurrence of papillary thyroid carcinoma?

BACKGROUND

Although the pattern of cervical lymph node metastases from papillary thyroid carcinoma (PTC) has been described, little is known about the pattern of lateral cervical nodal recurrence. The aim of this study was to establish the optimal strategy for neck dissection in patients who underwent reoperation for lateral cervical recurrence of PTC.

METHODS

We reviewed the records of 22 patients who underwent neck dissection for lateral nodal recurrence of thyroid cancer between 2002 and 2004. Eight patients had thyroid remnants or recurrent tumors in the bed and 6 had undergone lateral neck dissection prior to referral. Patients underwent comprehensive dissection of the posterolateral and ipsilateral (n = 10) or bilateral (n = 12) central neck. The pattern of nodal recurrence and postoperative morbidity were analyzed.

RESULTS

All patients had lateral compartment involvement, 91% at mid-lower, 45% at upper, and 18% at posterior sites. Central nodes were involved in 86% of patients: 82% at ipsilateral paratracheal, 32% at pretracheal, 27% at superior mediastinal, and 2 patients at contralateral sites. Skip lateral recurrence with no positive central nodes was rarely observed (14%). Postoperative vocal cord palsy (n = 1) and hypoparathyroidism (n = 5) developed only in patients undergoing bilateral central compartment dissection.

CONCLUSIONS

The inclusion of comprehensive ipsilateral central and lateral neck dissection in the reoperation for patients with lateral neck recurrence of PTC is an optimal surgical strategy.

Effect of topical mitomycin C for antrostomy in rabbit with sinusitis

The aim of this study is to evaluate if mitomycin C (MMC), applied topically at the site of maxillary antrostomy in experimentally inflamed maxillary sinuses, may reduce postoperative ostial stenosis without any harmful effect. Twenty-four rabbits with experimentally induced maxillary sinusitis underwent maxillary antrostomy bilaterally. MMC at a concentration of 0.4 or 1 mg/ml was applied at the site of antrostomy on the right whilst the antrostomy site on the left served as the control. Half of each MMC concentration group of animals were killed after 3 weeks, and the remaining half after 6 weeks. For every rabbit, the areas of antrostomies were measured and mucosal specimens around the ostia were obtained for microscopic evaluation at the time of antrostomy and killing. Within each MMC concentration group, MMC-treated antrostomies were significantly wider than those of the controls (P < 0.05), even after 6 weeks. However, comparison of the areas of MMC-treated antrostomies between the two MMC concentration groups did not show any significant difference (P > 0.05). No systemic side effect or permanent mucosal damage was detected. These results suggest that postoperative topical MMC at a concentration of 0.4 mg/ml can be used to prolong the patency of maxillary antrostomy in an inflammed sinus.

Endoscopic resection of pleomorphic adenoma arising in the nasopharynx

Pleomorphic adenoma is the commonest benign tumor of the salivary glands. It has rarely been reported arising in the nasopharynx. A pleomorphic adenoma originating from the left lateral wall of the nasopharynx was found in a 61-year-old female who presented with nasal obstruction and intermittent epistaxis. It was successfully removed by combined transnasal and transoral surgery under endoscopic visualization. Endoscope-guided surgery may be helpful for the complete resection of benign nasopharyngeal tumors whilst minimizing injury to the Eustachian tube openings or velopharynx.

Nasal cycle in patients with septal deviation: evaluation by acoustic rhinometry

The nasal cycle in patients with septal deviation was studied by acoustic rhinometric techniques. This study included 24 patients with anteriorly located septal deviations (mean age = 23.5), and 26 normal controls (mean age = 24.7). Data of MCA (minimum cross-sectional area) and NV (nasal volume), collected in 20-minute intervals, were plotted for each subject during 8 hours. Twenty of 24 patients (83%) with septal deviation and 20 of 26 normal subjects (77%) showed at least one complete cycle. Duration of the nasal cycle, which ranged from 100 minutes to 400 minutes, had no statistical difference between the septal deviation group (mean duration of 216 minutes) and the normal control group (mean duration of 227 minutes). The degrees of variation of MCA and NV, defined as Degree of Variation of MCA (%) = 100 (MCAmax - MCAmin)/MCAmax, Degree of Variation of NV (%) = 100 (NVmax - NVmin)/NVmax, which represent the percent change of MCA and NV throughout the study, showed no difference between the wide side and the narrow side, or between the septal deviation group and the normal control group. These findings suggest that the nasal cycle is relatively independent of peripheral anatomic factors for its generation. However, the amplitude of changes of MCA was greater in the wide side, and the sum of both MCAs tended to fluctuate in accordance with the fluctuation of MCA of the wide side. Thus, the nasal cycle seemed to be affected by septal deviation.

Plasma cell granuloma of the temporal bone: a case report

BACKGROUND

Plasma cell granuloma is a rare benign lesion which is found most frequently in the lungs, and a few cases have been described in the head and neck. In the middle ear and mastoid, a case of plasma cell granuloma was reported by Benton et al.

METHODS AND RESULTS

A 24-year-old woman was seen with a 7-month history of otalgia and decreased hearing. A computed tomographic (CT) scan showed a soft tissue mass occupying most of the mastoid bone. The mass and the contiguous dura were enhanced homogeneously on magnetic resonance imaging (MRI) scan. Microscopic examination showed plasma cell aggregates mixed with other inflammatory cells and Russell's bodies in a fibrous stroma. Immunoperoxidase studies revealed intracytoplasmic kappa and lambda light chains, and the lesion was confirmed as non-neoplastic and of polyclonal origin (ie, plasma cell granuloma). The patient was treated with conservative surgical excision (a canal-down mastoidectomy) and postoperative radiotherapy (5,040 cGy in 28 fractions) and remains free of disease 1 year after treatment.

CONCLUSIONS

A case of plasma cell granuloma is reported, and we believe this is the second case report of plasma cell granuloma affecting the temporal bone.

Distribution of substance P immunoreactive nerve fibers in the tracheal submucosal gland of cats

Immunohistochemistry combined with electron microscopy was employed to investigate the distribution of substance P-immunoreactive (SP-IR) nerve fibers in the tracheal submucosal gland of cats. The SP-IR nerve fibers were found to form a network around the glands. Numerous varicosities were also detected within the basement membrane of the acini and secretory tubules. All the intraglandular varicosities showed close spatial contact with serous cells, mucous cells, and myoepithelial cells. Our findings suggest that substance P-induced mucus secretion from tracheal submucosal glands in cats may be caused not only by a glandular contractile response of myoepithelial cells, but also by direct stimulation to both serous and mucous cells.