Roza Khalmuratova

Hypoxia-inducible Factor 1 Mediates Nasal Polypogenesis by Inducing Epithelial-to-Mesenchymal Transition

RATIONALE Nasal polyposis implies a refractory clinical course in case of chronic rhinosinusitis (CRS). Although hypoxia is believed to be associated with nasal polyposis, little is known about the mechanism underlying polypogenesis. OBJECTIVES To determine if hypoxia drives nasal polyposis by epithelial-to-mesenchymal transition (EMT). METHODS Immunoblotting, immunofluorescence, flow cytometry, and real-time polymerase chain reaction were performed to evaluate EMT and hypoxic markers in human nasal epithelial cells (hNECs) and in sinonasal tissues from patients with CRS with or without polyps. In addition, the effects of hypoxia-inducible factor (HIF)-1α inhibitors on nasal polypogenesis were investigated in a murine model. MEASUREMENTS AND MAIN RESULTS E-cadherin and α-smooth muscle actin (α-SMA) were down-regulated and up-regulated, respectively, in patients with polyps as compared with patients without polyps. Under hypoxia, hNECs transformed to a mesenchymal shape, and demonstrated representative changes in EMT markers; that is, mesenchymal markers (α-SMA, vimentin, and twist) increased but epithelial markers (E-cadherin and β-catenin) decreased. Mechanistically, E-cadherin level was recovered in hypoxia by silencing HIF-1α and decreased in normoxia by expressing HIF-1α. Furthermore, hypoxia was found to down-regulate PP2Ac phosphatase and up-regulate pSmad3, which led to α-SMA induction. In CRS sinonasal specimens, HIF-1α expression was found to correlate with E-cadherin loss and α-SMA expression. Finally, HIF-1α inhibitors suppressed nasal polypogenesis in a murine model. CONCLUSIONS hNECs undergo EMT during hypoxia and this process is critically mediated by HIF-1α and pSmad3. This study shows that hypoxia-induced EMT is likely to contribute to nasal polyposis in CRS, and suggests that HIF-1α be viewed as a therapeutic target for nasal polyposis.

Staphylococcus aureus enterotoxin B contributes to induction of nasal polypoid lesions in an allergic rhinosinusitis murine model.

Background Studies on the pathophysiology of nasal polyps in human subjects have been limited; thus an animal model is needed. There is increasing evidence supporting the role of Staphylococcus aureus enterotoxin B (SEB) in the pathogenesis of nasal polyposis. The aim of this study was to investigate the histological and immunologic effects of SEB on the formation of nasal polypoid lesions in an allergic rhinosinusitis murine model. Methods After induction of an ovalbumin (OVA)-induced allergic rhinosinusitis, OVA with SEB (5 or 500 ng) was instilled into the nasal cavity of mice for 8 weeks. Control mice did not receive SEB or OVA instillation. Histopathological changes were observed using hematoxylin and eosin, Sirius red, Giemsa, Massons trichrome, and Alcian blue stains. The levels of interleukin (IL)-4, IL-5, IL-8, IL-13, eotaxin, interferon gamma, total IgE, and OVA-specific IgE from serum or nasal lavage fluid were measured using enzyme-linked immunosorbent assay. Results The group treated with OVA plus 5 ng of SEB had significantly more mucosal lesions with epithelial disruption and nasal polypoid lesions than mice treated with OVA only, showing a significant increase in the infiltration of total inflammatory cells, eosinophils, and lymphocytes than the other groups. Levels of IL-5, eotaxin, and OVA-specific IgE in nasal lavage fluid were increased in the group treated with OVA plus 5 ng of SEB than in the other groups. A higher number of secretory cells in the groups treated with OVA plus SEB was observed than in other groups. Conclusion Low-dose SEB induced nasal polypoid lesions with an increased eosinophilic infiltration in an allergic rhinosinusitis murine model.

Clinical and histologic studies of olfactory outcomes after nasoseptal flap harvesting.

Since the introduction of an endonasal endoscopic approach in transsphenoidal pituitary surgery, reports of perioperative olfactory changes have presented conflicting results. We examined the incidence of olfactory loss in cases of endoscopic transsphenoidal pituitary surgery with skull base repair using the nasoseptal flap (NSF) and the effects of monopolar electrocautery commonly used in designing the NSF.

Colocalization of 5-HT1F receptor and calcitonin gene-related peptide in rat vestibular nuclei

The aim of this study was to determine whether calcitonin gene-related peptide (CGRP) colocalizes with 5-HT(1F) receptor in rat vestibular nuclei using a double immunohistochemical staining procedure. The frequent co-occurrence of migraine and balance disorders suggests a pathophysiologic link between the two. However, the mechanism of migrainous vertigo has not been elucidated, though serotonin (5-HT) and its receptors are believed to involve in the pathogenesis of migrainous vertigo. Furthermore, 5-HT(1F) receptor agonists and CGRP receptor antagonists have recently attracted attention as potential treatments for migraine, and CGRP release from trigeminal neurons has been associated with migraine. This study demonstrates the colocalization of 5-HT(1F) receptor and CGRP in the rat vestibular nuclei, which suggests that 5-HT(1F) receptor regulates the release of CGRP from vestibular nuclei. This finding indicates that 5-HT(1F) receptor agonists may ameliorate migrainous vertigo by attenuating elevated levels of CGRP release from vestibular nuclei.

Wound healing of nasal mucosa in a rat

Background Postoperative wound healing of the nasal mucosa is a highly organized process. However, this process still has not been fully understood. The present study aimed to establish a wound healing model in a rat and describe histomorphological changes of the nasal mucosa after mechanical injury. Methods Unilateral wound in the nasal cavity was induced using the brushing technique in 4-week-old, Sprague-Dawley rats. Experimental rats were divided into five groups (n = 7 for each group). Animals were killed 1 hour and 2, 5, 14, and 28 days after injury. The histological sections were examined for inflammatory cell infiltration, goblet, and ciliated cell formation in hematoxylin and eosin staining. The subepithelial and epithelial thicknesses were measured and expressed as the subepithelial thickness index (STI) and epithelial thickness index (ETI). Fibrosis was evaluated by subepithelial fibrosis index (SFI) in Massons trichrome–stained sections. Results Respiratory epithelial discontinuity and hemorrhage were observed 1 hour after injury. On day 2, edematous subepithelium and infiltration of neutrophils could be found on the injured site. Day 5 was characterized by the infiltration of monocytes and granulation tissue. SFI and ETI values increased significantly at day 14. Goblet cells and ciliated cells began to regenerate from day 14 and restored to near normal at day 28. Conclusion Using mechanical injury, the wound healing model of the nasal mucosa was established in a rat. The regeneration of respiratory mucosa was completed on day 28 after injury.

Effect of dexamethasone on wound healing of the septal mucosa in the rat.

Background Postoperative treatment after functional endoscopic sinus surgery (FESS) aims to modulate the wound healing process. Systemic or topically applied corticosteroids have been reported to be beneficial for improving nasal wound healing after FESS. However, few studies have investigated the effects of postoperative systemic steroids on nasal wound healing with regard to histological changes. The aim of this study was to evaluate the effect of systemic dexamethasone on nasal wound healing after mechanical injury in the rat. Methods A unilateral wound in the nasal cavity was induced using the brushing technique in 4-week-old, Sprague-Dawley rats (n = 70). Dexamethasone (0.15 mg/kg daily for 7 days) and normal saline were administered i.p. to the experimental and control groups (n = 35 for each) after the injury. The rats (n = 7 for each) were killed on days 2, 5,14, 28, and 42 after the injury. Histological changes in the nasal mucosa were examined and compared using hematoxylin and eosin and Massons trichrome staining. Results The experimental group showed less subepithelial edema formation and epithelial disarray at the early phase of the wound healing period. There were statistically significant differences in the subepithelial thickness and epithelial thickness indices between the experimental and control groups (p < 0.05). Ciliary and goblet cell indices were lower in the experimental group, which means that ciliary and goblet cell regeneration may be delayed by dexamethasone (p < 0.05). There were no differences in the subepithelial fibrosis index between the two groups. Adhesion formation between the nasal septum and turbinate were found only in the control group. Conclusion Systemic dexamethasone after mucosal injury may lessen subepithelial edema, goblet cell hyperplasia, and adhesion formation; however, it may cause delayed mucosal ciliary regeneration.

Colocalization of 5.HT1F receptor and glutamate in neurons of the vestibular nuclei in rats

Interplay between migraine and balance disorder morbidities has been a topic of interest for many years. Serotonin (5-HT) receptor is closely related with migraine and is associated with vestibular symptoms. The mechanism underlying migrainous vertigo, however, has not been determined. 5-HT1F receptor has recently attracted attention in the treatment of migraine, and the release of glutamate from trigeminal neurons has been implicated in migraine. In this study, the authors observed the colocalization of 5-HT1F receptor and glutamate in the vestibular nuclei of rats using double immunofluorescence, which suggests that 5-HT1F receptor might modulate glutamate release from the vestibular nuclei. The results of this study suggest that 5-HT1F receptor agonists represent a potential therapeutic strategy for migraine and balance disorders by blocking the release of glutamate.

Immunohistochemical and biomolecular identification of melatonin 1a and 1b receptors in rat vestibular nuclei

OBJECTIVE The aim of this study was to examine the localizations and expressions of melatonin 1a (MT1a) and 1b (MT1b) receptors in rat vestibular nuclei by immunohistochemical staining and reverse transcriptase-polymerase chain reaction. MATERIALS AND METHODS Twenty male Sprague-Dawley rats were used in this study. Antibodies for the MT1a and MT1b receptors were used in 10 rats, respectively. A further 10 animals were sacrificed for RT-PCR. Tissues containing medial vestibular nuclei were selectively isolated from brain stem slices for RT-PCR. RESULTS MT1a and MT1b receptor immunopositive neurons were found to be distributed throughout the four major vestibular nuclei. Both receptors were primarily detected in neuronal somata and their proximal dendrites. The presences of the mRNAs of the MT1a and MT1b receptors were confirmed by RT-PCR in medial vestibular nuclei and trigeminal ganglia. CONCLUSIONS The present study demonstrates, for the first time, that MT1a and MT1b receptors are localized and expressed in rat vestibular nuclei. This study provides additional insight into the role of melatonin receptors during vestibular signal processing.

Roles of periostin in symptom manifestation and airway remodeling in a murine model of allergic rhinitis.

Purpose Periostin was originally identified as a secreted factor during screening of a mouse osteoblastic library. In a recent study, periostin was found to directly regulate eosinophil accumulation in allergic mucosal inflammation. Chronic eosinophilic inflammation is related to the development of remodeling. The present study examined the expression of periostin and evaluated its role in the inflammatory process and remodeling associated with allergic rhinitis. Methods A murine model of allergic rhinitis was established in periostin knockout mice. We analyzed the expression of periostin, manifestation of nasal symptoms, eosinophilic inflammation, and subepithelial fibrosis as well as the expression of MMP-2, TIMP-1, and type 1 collagen in nasal tissue. Results Periostin was mainly distributed in the subepithelial tissue of the nasal mucosa. The subepithelial tissue was thinner in the knockout group than in the control group. No differences in the expression of MMP-2 or TIMP-1 were found in the knockout group. However, after a month of allergen challenge, type I collagen in the nasal tissue was lower in the knockout group than in the control group. The number of eosinophils and the symptom score were also lower in the knockout group. Conclusions Periostin is expressed in nasal tissues of murine models of allergic rhinitis. Periostin deficiency may affect the remodeling of nasal tissue with reduced subepithelial fibrosis, and lead to less eosinophilic inflammation.

Quantitative Analysis of Myosin Heavy Chain Expression Change in Laryngeal Muscle after Irradiation in Rats

Purpose Radiotherapy for head and neck cancer does not impair the voice quality as much as laser treatment or surgery, but it can induce muscle wasting and fibrosis and symptoms of dry mouth. We investigated the effect of irradiation on the myosin heavy chain (MyHC) expression in laryngeal muscles. Materials and Methods Rats were irradiated with one dose of 10, 15, 20, 25, 30, or 35 Gy and other rats were irradiated with 20 Gy. The thyroarytenoid (TA), posterior cricoarytenoid (PCA), and cricothyroid (CT) muscles were subjected to reverse transcription-polymerase chain reaction (RT-PCR). Results Two weeks after irradiation with 10, 15, or 20 Gy, all the MyHC type expressions had decreased in a dose-dependent manner in the TA, PCA, and CT muscles, and especially the expression of MyHC IIa decreased much more than the expressions of the other MyHC isoforms in all muscles. In the 20 Gy-irradiated rats, almost all the MyHC isoform expressions declined over 12 weeks in the TA, PCA, and CT muscles, except for the MyHC I expression in the PCA and CT muscle. The MyHC IIa expression was markedly decreased in all the muscles. Conclusion The laryngeal muscles responded differently to radiation, but they showed a time-dependent and long-lasting decrease in the expressions of all the MyHC isoforms in the TA, PCA, and CT muscles. In particular, the expression of the MyHC IIa isoform in all the muscles may be more sensitive to irradiation than the expressions of the other MyHC isoforms.