Paramita Baruah

Cholesteatoma is abnormal epithelial tissue in the middle ear cleft and an important cause of chronically discharging ears and hearing loss. Its proximity to important middle ear structures and the brain can lead to significant complications. Cholesteatoma presents both as congenital and acquired types and can occur both in children and adults. The mainstay of treating cholesteatoma is a destructive surgery with attendant morbidity. Despite radical surgery cholesteatomas can recur, sometimes repeatedly, causing a significant impact on quality of life. The role of inflammation in cholesteatoma is an area of keen interest. However, immune processes are highly complex, and while various individual components of the process have been studied in cholesteatoma, we are far from a cohesive understanding of the role of immune cells and inflammation pathways in the pathogenesis of cholesteatoma. Better understanding of its immune-pathogenesis would enable identification of disease-modifying therapies and novel pharmacological targets. In this review, we provide a detailed overview of the existent knowledge and recent developments on immune cells and inflammatory pathways implicated in cholesteatoma pathogenesis, progression, and damaging bone eroding properties. As cholesteatoma surgery is inherently destructive with poor hearing results, there is a definite necessity for new treatments to reduce the surgical burden and enable functional preservation in the management of this condition. We focus on the current and future areas of research that could lead to new therapies targeting inflammation and bring about a step change in the management of this aggressive ear condition.

Background and aim: Head and neck paragangliomas (HNPGN) are tumours that carry significant morbidity The role of the stroma in the pathogenesis of HNPGN is not completely understood. This study explores the profile of fibroblasts and macrophages in HNPGN.Methods: Ten patients undergoing HNPGN surgery were recruited. CD68 and CD163 immunohistochemistry was performed for macrophage analysis; CD90 and podoplanin (PDPN) expression was examined to identify fibroblasts. RT-qPCR was performed on HNPGN tissue for macrophage- and fibroblast-associated molecules. Fibroblast cultures were established from HNPGN were analysed by RT-qPCR and flowcytometry. Confocal microscopy for MCT1 and MCT4 was performed in HNPGN.Results: CD68 and CD163 expressing macrophages were noted in HNPGN. CD90 and PDPN expressing cells were present in HNPGN. RT-qPCR analysis showed expression of phenotypic and functional macrophage- and fibroblast-associated molecules in HNPGN. RT-qPCR analysis of fibroblasts cultured from HNPGN confirmed the expression of several molecules including PDPN at comparable levels to healthy tissue fibroblasts. Expression of FAP, MCT-1, insulin receptor (CD220) and insulin growth factor receptor-2 (CD222) was noted on HNPGN derived fibroblasts on flowcytometry. MCT1 and MCT4 were expressed in HNPGN tumour cells and stromal macrophages in-situ.Conclusion: Fibroblasts and macrophages are present in the HNPGN tumour microenvironment, and several macrophage and fibroblast functional markers are expressed in HNPGN. Macrophages in HNPGN tissue express metabolic markers MCT1 and MCT4. Further analysis of the fibroblast and macrophage function in HNPGN will improve our understanding of their potential roles in tumour pathogenesis.

Background: Vestibular schwannomas (VSs) remain a challenge due to their anatomical location and propensity to growth. Macrophages are present in VS but their roles in VS pathogenesis remains unknown. Objectives: The objective was to assess phenotypic and functional profile of macrophages in VS with single-cell RNA sequencing (scRNAseq). Methods: scRNAseq was carried out in three VS samples to examine characteristics of macrophages in the tumour. RT-qPCR was carried out on 10 VS samples for CD14, CD68 and CD163 and a panel of macrophage-associated molecules. Results: scRNAseq revealed macrophages to be a major constituent of VS microenvironment with three distinct subclusters based on gene expression. The subclusters were also defined by expression of CD163, CD68 and IL-1β. AREG and PLAUR were expressed in the CD68+CD163+IL-1β+ subcluster, PLCG2 and NCKAP5 were expressed in CD68+CD163+IL-1β− subcluster and AUTS2 and SPP1 were expressed in the CD68+CD163−IL-1β+ subcluster. RT-qPCR showed expression of several macrophage markers in VS of which CD14, ALOX15, Interleukin-1β, INHBA and Colony Stimulating Factor-1R were found to have a high correlation with tumour volume. Conclusions: Macrophages form an important component of VS stroma. scRNAseq reveals three distinct subsets of macrophages in the VS tissue which may have differing roles in the pathogenesis of VS.

Objectives: Acute mastoiditis (AM) and its associated intra and extracranial complications are rare complications of acute otitis media. However, they are associated with a high morbidity. The management of AM with complications carries significant variations in approach. We aimed to evaluate the presentation of children with AM with complications to a tertiary referral centre in the United Kingdom and describe evolution of the treatment approaches.Methods: We undertook a retrospective chart review of all children admitted with AM to the University Hospitals of Leicester between 2013 and 2022.Results: Twenty‐seven children were included in this study: 7 patients had sigmoid sinus thrombosis (SST), 4 had an intracranial collection, 3 had cranial nerve palsy and 16 had a subperiosteal abscess (SPA); some patients had more than 1 complication. In this study, treatment of SPA with incision and drainage (I&D) and grommet insertion was effective, as all patients treated with grommet insertion and I&D recovered well and did not require a subsequent cortical mastoidectomy. All patients with SST received anticoagulation and intravenous (IV) antibiotics; surgical input consisted of grommet insertion alone and cortical mastoidectomy was not routinely performed in these patients.Conclusion: In our series, management of SPA with grommet insertion and drainage had good outcomes. SST management mainly consisted of IV antibiotics, anticoagulation and grommet insertion with good recovery. The evidence to guide the management of complications of mastoiditis is of poor quality and further research is needed to clarify the optimal management of these complications.

Background and aim: Vestibular schwannomas (VSs), despite being histologically benign, cause significant morbidity because of their challenging intracranial location and the propensity for growth. The role of the stroma and particularly fibroblasts, in the progression of VS, is not completely understood. This study examines the profile of fibroblasts in VS. Methods: Seventeen patients undergoing surgical excision of VS were recruited into the study. Reverse transcription with quantitative polymerase chain reaction (RT-qPCR) was performed on VS tissue samples and fibroblast-associated molecules examined. Immunofluorescence and immunohistochemistry in VS tissue were used to study the expression of fibroblast markers CD90 and podoplanin in situ. Fibroblast cultures were established from VS, and RT-qPCR analysis was performed on a panel of fibroblast markers on VS and control tissue fibroblasts. Results: Several fibroblast-associated molecules including members of galectin family and matrix metalloproteinases were found to be expressed in VS tissue on RT-qPCR analysis. In situ, expression of CD90 and podoplanin was observed in VS tissue both on immunohistochemistry and immunofluorescence. RT-qPCR analysis of fibroblasts from VS and control vestibular neuroepithelium (NE) showed a higher expression of several molecules of the galectin and matrix metalloproteinases family on VS fibroblasts compared with NE fibroblasts. Conclusion: This work examines fibroblasts from VS and shows qualitative differences from NE fibroblasts on RT-qPCR. Further understanding of the fibroblast function in the progression of VS will potentially unveil new targets to manage VS growth.

Objective This study aimed to assess whether increasing operative experience results in better surgical outcomes in endoscopic middle-ear surgery. Methods A retrospective single-institution cohort study was performed. Patients underwent endoscopic tympanoplasty between May 2013 and April 2019 performed by the senior surgeon or a trainee surgeon under direct supervision from the senior surgeon. Following data collection, statistical analysis compared success rates between early (learning curve) surgical procedures and later (experienced) tympanoplasties. Results In total, 157 patients (86 male, 71 female), with a mean age of 41.6 years, were included. The patients were followed up for an average of 43.2 weeks. The overall primary closure rate was 90.0 per cent. Conclusion This study demonstrates an early learning curve for endoscopic ear surgery that improves with surgical experience. Adoption of the endoscopic technique did not impair the success rates of tympanoplasty.

Background: The co-inhibitory receptor PD-1 is expressed in many tumors including head and neck squamous cell carcinoma (HNSCC) and is an important immunotherapy target. However, the role of PD-1 ligands, PD-L1, and particularly PD-L2, in the tumor-stromal cell interactions that cause a tumor-permissive environment in HNSCC is not completely understood and is the focus of our study. Methods: Expression of PD-L1 and PD-L2 was analyzed by immunohistochemistry in situ in HNSCC tumor tissue. Co-cultures were established between stromal cells (fibroblasts and macrophages) and human papilloma virus (HPV)-positive and HPV-negative HNSCC cell lines (HNSCCs) and PD-1 ligands expression was analyzed using flow cytometry. Results: PD-L1 and PD-L2 were expressed both in tumor cells and stroma in HNSCC tissue in situ. In vitro, basal expression of PD-L1 and PD-L2 was low in HNSCCs and high on fibroblasts and macrophages. Interestingly, HPV-positive but not HPV-negative HNSCCs increased the expression of both PD-1 ligands on fibroblasts upon co-culture. This effect was not observed with macrophages. Conversely, both fibroblasts and macrophages increased PD-1 ligands on HPV-positive HNSCCs, whilst this was not observed in HPV-negative HNSCCs. Crucially, we demonstrate that up-regulation of PD-L1 and PD-L2 on fibroblasts by HPV-positive HNSCCs is mediated via TLR9. Conclusions: This work demonstrates in an in vitro model that HPV-positive HNSCCs regulate PD-L1/2 expression on fibroblasts via TLR9. This may open novel avenues to modulate immune checkpoint regulator PD-1 and its ligands by targeting TLR9.