A murine model of cholesteatoma-induced bone resorption using autologous dermal implantation

Higher degree of keratinization correlated with severe bone destruction in acquired Cholesteatoma

BACKGROUND

Acquired cholesteatoma is characterized by hyper-keratinized squamous epithelium and bone destruction. However, direct evidence for hyper-keratinized epidermis promoting bone destruction is lacking.

AIMS/OBJECTIVES

To determine whether higher degree of keratinization correlated with severe bone destruction and further offer direct evidence for keratinocyte-inducing osteoclastogenesis.

MATERIALS AND METHODS

Histological changes and clinical relevance were analyzed in human-acquired cholesteatoma. Animal models were established by implanting autologous epidermis with different degrees of keratinization. The severity of bone resorption and the number of osteoclasts were compared in different keratinized groups. An in vitro coculture system was developed to mimic the progress of keratinocyte-inducing osteoclastogenesis.

RESULTS

The matrix of cholesteatoma was composed of a thicker stratum corneum than normal skin. The stratum corneum thickness and the expression of Keratin 10 positively correlated to the severity of bone destruction. Animal models revealed that the bone destruction induced by a higher keratinized epidermis was more severe. Osteoclasts were detected in bone erosion areas, and the number of osteoclasts increased with the keratinization degrees of the graft. In vitro studies showed that keratinocytes directly promoted monocytes differentiating into osteoclasts.

CONCLUSIONS AND SIGNIFICANCE

In acquired cholesteatoma, the degree of keratinization correlated with disease severity, and keratinocytes directly promote osteoclastogenesis.

Serum sclerostın levels ın chronıc otıtıs medıa wıth and wıthout cholesteatoma

SUMMARY OBJECTIVE Sclerostin is a glycoprotein that plays a catabolic role in bone and is involved in the regulation of bone metabolism by increasing the osteoclastic bone resorption. In this study, serum sclerostin levels were measured in chronic otitis media (COM) with and without cholesteatoma, assuming that it might have a role in the aetiopathogenesis of bone resorption. METHODS A total of 44 patients with cholesteatomatous COM (cCOM) (n = 22) and non-cholesteatomatous COM (ncCOM) (n = 22) were included in this study, and 26 healthy volunteers without any chronic ear disease problem(s) constituted the control group (n = 26). RESULTS No significant difference was not found in terms of serum iPTH, ALP, and vitamin D levels between ncCOM, cCOM, and the control groups. A significant difference was found in terms of serum sclerostin, Ca, and P levels between ncCOM, cCOM, and the control groups (p<0.05). Serum sclerostin levels in the study groups were significantly higher but their serum Ca and P levels were significantly lower compared to the control group. CONCLUSION We think that serum sclerostin concentrations, which were significantly higher in patients with cCOM and ncCOM compared to healthy controls are associated with bone erosion. There is a need for further studies with larger samples in order to determine the relationship between sclerostin and bone erosion in cholesteatoma to help in establishing preventive measures against cholesteatoma and set new targets for the development of non-surgical treatments.

Stem Cell-Induced Inflammation in Cholesteatoma is Inhibited by the TLR4 Antagonist LPS-RS

Cholesteatoma is a severe non-cancerous lesion of the middle ear characterized by massive inflammation, tissue destruction, and an abnormal growth of keratinized squamous epithelium. We recently demonstrated the presence of pathogenic stem cells within cholesteatoma tissue, unfortunately their potential roles in regulating disease-specific chronic inflammation remain poorly understood. In the presented study, we utilized our established human in vitro cholesteatoma stem cell model for treatments with lipopolysaccharides (LPS), tumor necrosis factor α (TNFα), and the TLR4-antagonist LPS from R. sphaeroides (LPS-RS) followed by qPCR, western blot, and immunocytochemistry. Middle ear cholesteatoma stem cells (ME-CSCs) showed a significantly increased expression of TLR4 accompanied by a significantly enhanced LPS-dependent pro-inflammatory gene expression pattern of TNFα, IL-1α, IL-1ß, IL-6, and IL-8 compared to non-pathogenic control cells. LPS-dependent pro-inflammatory gene expression in ME-CSCs was driven by an enhanced activity of NF-B p65 leading to a TNFα-mediated feed-forward-loop of pro-inflammatory NF-B target gene expression. Functional inactivation of TLR4 via the TLR4-antagonist LPS-RS blocked chronic inflammation in ME-CSCs, resulting in a nearly complete loss of IL-1ß, IL-6, and TNFα expression. In summary, we determined that ME-CSCs mediate the inflammatory environment of cholesteatoma via TLR4-mediated NF-B-signaling, suggesting a distinct role of ME-CSCs as drivers of cholesteatoma progression and TLR4 on ME-CSCs as a therapeutic target.

Single dose intratympanic mesna application inhibits propylene glycol induced cholesteatoma formation

Objective:

Mesna (i.e. sodium 2-mercaptoethanesulfonate; C2H5NaO3S2) has been used in otological surgery such as cholesteatoma dissection and tympanic membrane lateralisation in atelectatic ears. However, this study aimed to investigate its effect on cholesteatoma formation.

Methods:

A total of 20 Wistar rats were divided into two groups of 10 animals. The right and left ears of control animals were treated with saline (saline control group; n = 10 ears) and propylene glycol plus saline (propylene glycol control group; n = 10 ears), respectively. In the mesna group, both ears were treated with propylene glycol plus mesna (n = 20 ears). On days 1, 8 and 15, the saline control group had intratympanic injections of 0.2 ml saline and the propylene glycol control and mesna groups had intratympanic injections of 0.2 ml 100 per cent propylene glycol. On day 22, the propylene glycol control group had a single intratympanic injection of 0.2 ml saline and the mesna group had a single intratympanic injection of 10 per cent mesna. Animals were killed 12 weeks after the last injection and the temporal bones were sent for histopathological evaluation.

Results:

The cholesteatoma formation rate was 88 per cent in the propylene glycol control group, but was significantly lower in the mesna group (p = 0.01). There were no significant differences in granulation tissue formation (p = 0.498), cyst formation in the bulla (p = 0.381), fibrosis (p = 0.072) and epithelial hyperplasia (p = 0.081) among experimental groups.

Conclusion:

Intratympanic propylene glycol administration is an effective method of promoting experimental cholesteatoma formation. Administration of a single dose of intratympanic mesna inhibited cholesteatoma formation in an animal model.

TREM-2 promotes acquired cholesteatoma-induced bone destruction by modulating TLR4 signaling pathway and osteoclasts activation

Triggering receptor expressed on myeloid cells (TREM) has been broadly studied in inflammatory disease. However, the expression and function of TREM-2 remain undiscovered in acquired cholesteatoma. The expression of TREM-2 was significantly higher in human acquired cholesteatoma than in normal skin from the external auditory canal, and its expression level was positively correlated with the severity of bone destruction. Furthermore, TREM-2 was mainly expressed on dendritic cells (DCs). In human acquired cholesteatoma, the expression of proinflammatory cytokines (IL-1β, TNF-α and IL-6) and matrix metalloproteinases (MMP-2, MMP-8 and MMP-9) were up-regulated, and their expression levels were positively correlated with TREM-2 expression. Osteoclasts were activated in human acquired cholesteatoma. In an animal model, TREM-2 was up-regulated in mice with experimentally acquired cholesteatoma. TREM-2 deficiency impaired the maturation of experimentally acquired cholesteatoma and protected against bone destruction induced by experimentally acquired cholesteatoma. Additional data showed that TREM-2 up-regulated IL-1β and IL-6 expression via TLR4 instead of the TLR2 signaling pathway and promoted MMP-2 and MMP-8 secretion and osteoclast activation in experimentally acquired cholesteatoma. Therefore, TREM-2 might enhance acquired cholesteatoma-induced bone destruction by amplifying the inflammatory response via TLR4 signaling pathways and promoting MMP secretion and osteoclast activation.

Animal models of middle ear cholesteatoma

Middle ear acquired cholesteatoma is a pathological condition associated with otitis media, which may be associated with temporal bone resorption, otorrhea and hearing loss, and occasionally various other complications. Cholesteatoma is characterized by the enhanced proliferation of epithelial cells with aberrant morphologic characteristics. Unfortunately, our understanding of the mechanism underlying its pathogenesis is limited. To investigate its pathogenesis, different animal models have been used. This paper provides a brief overview of the current status of research in the field of pathogenesis of middle ear acquired cholesteatoma, four types of animal models previously reported on, up-to-date cholesteatoma research using these animal models, our current studies of the local hybrid ear model, and the future prospect of new animal models of middle ear cholesteatoma.

Progressive massive osteolysis secondary to benign squamous epithelial colonisation in chronic osteomyelitis

Although the rare complication of squamous cell carcinoma in chronic osteomyelitis is well known, benign squamous epithelial proliferation can also occur, causing osteolysis and fracture. The radiological and correlated pathological features of osteolysis from this benign complication of chronic osteomyelitis are presented.