The extracellular matrix dictates regional competence for tumour initiation.

The skin epidermis is constantly renewed throughout life1,2. Disruption of the balance between renewal and differentiation can lead to uncontrolled growth and tumour initiation3. However, the ways in which oncogenic mutations affect the balance between renewal and differentiation and lead to clonal expansion, cell competition, tissue colonization and tumour development are unknown. Here, through multidisciplinary approaches that combine in vivo clonal analysis using intravital microscopy, single-cell analysis and functional analysis, we show how SmoM2-a constitutively active oncogenic mutant version of Smoothened (SMO) that induces the development of basal cell carcinoma-affects clonal competition and tumour initiation in real time. We found that expressing SmoM2 in the ear epidermis of mice induced clonal expansion together with tumour initiation and invasion. By contrast, expressing SmoM2 in the back-skin epidermis led to a clonal expansion that induced lateral cell competition without dermal invasion and tumour formation. Single-cell analysis showed that oncogene expression was associated with a cellular reprogramming of adult interfollicular cells into an embryonic hair follicle progenitor (EHFP) state in the ear but not in the back skin. Comparisons between the ear and the back skin revealed that the dermis has a very different composition in these two skin types, with increased stiffness and a denser collagen I network in the back skin. Decreasing the expression of collagen I in the back skin through treatment with collagenase, chronic UV exposure or natural ageing overcame the natural resistance of back-skin basal cells to undergoing EHFP reprogramming and tumour initiation after SmoM2 expression. Altogether, our study shows that the composition of the extracellular matrix regulates how susceptible different regions of the body are to tumour initiation and invasion.

Allele-specific expression reveals genetic drivers of tissue regeneration in mice.

In adult mammals, skin wounds typically heal by scarring rather than through regeneration. In contrast, "super-healer" Murphy Roths Large (MRL) mice have the unusual ability to regenerate ear punch wounds; however, the molecular basis for this regeneration remains elusive. Here, in hybrid crosses between MRL and non-regenerating mice, we used allele-specific gene expression to identify cis-regulatory variation associated with ear regeneration. Analyzing three major cell populations (immune, fibroblast, and endothelial), we found that genes with cis-regulatory differences specifically in fibroblasts were associated with wound-healing pathways and also co-localized with quantitative trait loci for ear wound-healing. Ectopic treatment with one of these proteins, complement factor H (CFH), accelerated wound repair and induced regeneration in typically fibrotic wounds. Through single-cell RNA sequencing (RNA-seq), we observed that CFH treatment dramatically reduced immune cell recruitment to wounds, suggesting a potential mechanism for CFH's effect. Overall, our results provide insights into the molecular drivers of regeneration with potential clinical implications.

Effects of ultrashort wave diathermy on skin wounds in rabbit ears.

PURPOSE: Ultrashort wave diathermy (USWD) is commonly used in diseases associated with osteoarticular and soft tissue injuries. However, while accelerating wound healing and preventing joint stiffness, there have been few reports on whether it leads to excessive hypertrophic scarring. The aim was to investigate the effects of different doses of USWD on hypertrophic scars. MATERIALS AND METHODS: A rabbit model of hypertrophic scars was used to determine which dose of USWD reduced scar hyperplasia. The scar thickness was calculated using Sirius red staining. All protein expression levels were determined by western blotting, including fibrosis, collagen deposition, and neoangiogenesis related proteins. Subsequently, flow cytometry and ELISAs were used to determine the proportions of macrophage and inflammatory levels. RESULTS: The wounds with USWD in histopathology showed the dermis was more markedly thickened in the 120 mA group, whereas the wounds with the 60 mA were less raised, comparing with the 0 mA; all detected protein levels were increased significantly, the 120 mA group comparing with the others, including heat shock, fibrosis, and neoangiogenesis, whereas the collagen deposition relative protein levels were decreased, the 60 mA group comparing with Sham group; Finally, in the proportion of macrophages and inflammatory levels the 120 mA group were the highest, and the group Sham was lower than group 60 mA. CONCLUSIONS: In hypertrophic scars, the 60 mA USWD could relieve scar formation and inflammatory reactions; however, higher doses could result in opposite consequences.

Auriculocondylar syndrome: Pathogenesis, clinical manifestations and surgical therapies.

Auriculocondylar syndrome (ARCND) is a genetic and rare craniofacial condition caused by abnormal development of the first and second pharyngeal arches during the embryonic stage and is characterized by peculiar auricular malformations (question mark ears), mandibular condyle hypoplasia, micrognathia and other less-frequent features. GNAI3, PLCB4 and EDN1 have been identified as pathogenic genes in this syndrome so far, all of which are implicated in the EDN1-EDNRA signal pathway. Therefore, ARCND is genetically classified as ARCND1, ARCND2 and ARCND3 based on the mutations in GNAI3, PLCB4 and EDN1, respectively. ARCND is inherited in an autosomal dominant or recessive mode with significant intra- and interfamilial phenotypic variation and incomplete penetrance, rendering its diagnosis difficult and therapies individualized. To raise clinicians' awareness of the rare syndrome, we focused on the currently known pathogenesis, pathogenic genes, clinical manifestations and surgical therapies in this review.

Benefits of medially based perichondrio-adipo-dermal flap in cartilage sparing prominent ear surgery.

BACKGROUND: Cartilage-cutting and cartilage-sparing techniques are the two types of otoplasty procedures. Because of the significant risk of haematoma, skin necrosis, and ear deformity, cartilage-cutting techniques have been questioned. As a result; suture-based cartilage-sparing procedures such as Mustarde and Furnas suture procedures have grown in popularity. However, these techniques have a tendency for deformity recurrence due to cartilage memory and suture fatigue, as well as the possibility of suture extrusion and pinpricking sensation of the sutures. METHODS: In this study, we used a medially based adipo-dermal flap including perichondrium which is elevated from the back of the auricle to cover and support a cartilage-sparing otoplasty, thirty-four patients (14 female and 20 male) were operated using this technique. The medially based perichondrio-adipo-dermal flap is advanced anteriorly and fixed to the helical rim under cover of the distal skin flap. This procedure sought to cover the suture line preventing suture extrusion and support in the repair of the deformity preventing its recurrence. RESULTS: The average operative time was 80min, ranging from 65 to 110min. The patients passed the early postoperative period uneventfully except for 2 patients; one patient (2.9%) developed haematoma, and the other patient developed a small area of necrosis on the new antihelical fold. In late the postoperative period recurrence of the deformity developed in one patient. No patients developed suture extrusion or granuloma. CONCLUSION: The treatment to repair prominent ears is easy and safe, with benefits such as a natural-looking antihelical fold and minimal tissue stress. The medially or proximally based adipo-dermal flap may help to lower recurrence rates and suture extrusion.

A Mouse Ear Model for Allergic Contact Dermatitis Evaluation.

Skin is the human body's first line of defense and one of the most exposed organs to environmental chemicals. Allergic contact dermatitis (ACD) is a common skin disease that manifests as a local rash, redness, and skin lesions. The occurrence and development of ACD are influenced by both genetic and environmental factors. Although many scholars have constructed a series of models of ACD in recent years, the experimental protocols of these models are all different, which makes it difficult for readers to establish them well. Therefore, a stable and efficient animal model is of great significance to further study the pathogenesis of atopic dermatitis. In this study, we detail a modeling method using 1-fluoro-2,4-dinitrobenzene (DNFB) to induce ACD-like symptoms in the ears of mice and describe several methods for assessing the severity of dermatitis during modeling. This experimental protocol has been successfully applied in some experiments and has a certain promotional role in the field of ACD research.

[Effect analysis of individualized operation for congenital preauricular fistula].

Objective:To investigate the effect and influencing factors of individualized operation for congenital preauricular fistula in children. Methods:The clinical data of 98 cases （109 ears） of congenital preauricular fistula treated in Department of Otolaryngology，Fuzhou Children's Hospital of Fujian Medical University from July 2016 to December 2020 were retrospectively analyzed. According to the characteristics and infection of preauricular fistula，they were divided into common type and variant type，static period of inflammation and period of infection.Individual surgical methods such as classical fistula resection, double fusiform incision and fistula location resection were used respectively.The efficacy，complication and influencing factors of different surgical methods were analyzed. Results:The operation time of classical fistula resection was shorter, and the difference was statistically significant（t = －2.905 and－3.005 respectively, all P<0.05）. According to the stages and types of fistulas, the selection of individualized surgical methods had achieved good results. There was no significant difference in incision complications and fistula recurrence among different surgical methods （all P>0.05）. Conclusion:Once infection occurs in congenital preauricular fistula, surgical resection should be performed as soon as possible after infection control, or as early as possible after infection maximum control if infection cannot completely subside. Surgical incision design should be individualized, complete resection of fistulas and lesions, minimally invasive and aesthetic.

Perforación timpánica y colesteatoma, una patología de niños y adultos / Tympanic perforation and cholesteatoma, a pathology of children and adults

INTRODUCCIÓN. La patología de oído es una enfermedad frecuente en nuestro medio, asociada a infecciones a repetición del oído, con la presencia de perforación timpánica y colesteatoma, que determinará la presencia de lesiones mucho más acentuadas en cuanto a la evolución auditiva o complicaciones locales o sistémicas. OBJETIVO. Determinar la asociación existente entre la presencia de colesteatoma y perforación timpánica en pacientes con otitis media crónica. MATERIALES Y MÉTODOS. Estudio epidemiológico analítico retrospectivo. Población de 4 733 y muestra de 75 pacientes para casos y 75 para controles basados en historias clínicas tomadas del sistema informático AS 400, que acudieron a la consulta externa de torrinolaringología del Hospital de Especialidades Carlos Andrade Marín en el periodo de enero de 2018 a diciembre de 2019; Criterios de inclusión para grupo de casos: Hombres y mujeres de 20 a 65 años de edad, diagnóstico de otitis media crónica, diagnóstico de colesteatoma ótico. Criterios de inclusión para grupo controles: Hombres y mujeres de 20 a 65 años de edad, no presentar diagnóstico de colesteatoma. RESULTADOS. Se observó una relación fuerte entre el poseer perforación timpánica y el desarrollo de colesteatoma con un valor de OR 33,14 con un IC al 95% de 31,94 ­ 34,34, con lo que se comprobó la hipótesis del estudio. Se determinó que la perforación timpánica es un factor de riesgo asociado con el desarrollo de colesteatoma en pacientes con otitis media crónica, la prevalencia de colesteatoma en relación a la edad estuvo en un 72% en pacientes de 41 a 65 años, con mayor predominancia en mujeres en un 57,3%. DISCUSIÓN. La presencia de perforación timpánica de acuerdo a lo observado es un factor de riesgo para el desarrollo de colesteatoma, ligado en su mayoría a cuadros de Otitis Media Crónica. CONCLUSIONES. Se confirmó que la perforación timpánica, es un factor de riesgo en el desarrollo del colesteatoma en los pacientes que tienen otitis media crónica, lo que demuestra la necesidad de manejo actualizado y continuo en pacientes con esta patología de oído. Se requieren estudios con muestras más amplias para determinar otros factores de riesgo como sexo, nivel de educación y edad que podrían influir en el desarrollo de colesteatoma.

INTRODUCTION. Ear pathology is a frequent disease in our environment, associated with repeated ear infections, with the presence of tympanic perforation and cholesteatoma, which will determine the presence of much more accentuated lesions in terms of auditory evolution or local or systemic complications. OBJECTIVE. To determine the association between the presence of cholesteatoma and tympanic perforation in patients with chronic otitis media. MATERIALS AND METHODS. Retrospective analytical epidemiological study. Population of 4 733 and sample of 75 patients for cases and 75 for controls based on clinical histories taken from the AS 400 computer system, who attended the Otorhinolaryngology outpatient clinic of the Carlos Andrade Marín Specialties Hospital in the period from January 2018 to December 2019; Inclusion criteria for case group: Men and women aged 20 to 65 years, diagnosis of chronic otitis media, diagnosis of otic cholesteatoma. Inclusion criteria for controls group: men and women aged 20 to 65 years, no diagnosis of cholesteatoma. RESULTS. A strong relationship was observed between having tympanic perforation and the development of cholesteatoma with an OR value of 33,14 with a 95% CI of 31,94 - 34,34, thus proving the study hypothesis. It was determined that tympanic perforation is a risk factor associated with the development of cholesteatoma in patients with chronic otitis media, the prevalence of cholesteatoma in relation to age was 72% in patients aged 41 to 65 years, with greater predominance in women in 57,3%. DISCUSSION. The presence of tympanic perforation according to what was observed is a risk factor for the development of cholesteatoma, mostly linked to Chronic Otitis Media. CONCLUSIONS. It was confirmed that tympanic perforation is a risk factor in the development of cholesteatoma in patients with chronic otitis media, which demonstrates the need for updated and continuous management in patients with this ear pathology. Studies with larger samples are required to determine other risk factors such as sex, education level and age that could influence the development of cholesteatoma.

Necrosis of the Ear Following Skin Cancer Resection.

We report 2 patients who underwent Mohs micrographic surgery (MMS) and operative closure on the ear. Both cases were complicated by necrosis resulting in the formation of auricular defects. These cases highlight the importance of the auricular vasculature and the associated watershed regions during operative planning for MMS as well as the complications that can arise with vascular compromise. This case report also provides a review of the auricular vasculature with special attention to these vulnerable watershed regions.

New locus underlying auriculocondylar syndrome (ARCND): 430 kb duplication involving TWIST1 regulatory elements.

BACKGROUND: Auriculocondylar syndrome (ARCND) is a rare genetic disease that affects structures derived from the first and second pharyngeal arches, mainly resulting in micrognathia and auricular malformations. To date, pathogenic variants have been identified in three genes involved in the EDN1-DLX5/6 pathway (PLCB4, GNAI3 and EDN1) and some cases remain unsolved. Here we studied a large unsolved four-generation family. METHODS: We performed linkage analysis, resequencing and Capture-C to investigate the causative variant of this family. To test the pathogenicity of the CNV found, we modelled the disease in patient craniofacial progenitor cells, including induced pluripotent cell (iPSC)-derived neural crest and mesenchymal cells. RESULTS: This study highlights a fourth locus causative of ARCND, represented by a tandem duplication of 430 kb in a candidate region on chromosome 7 defined by linkage analysis. This duplication segregates with the disease in the family (LOD score=2.88) and includes HDAC9, which is located over 200 kb telomeric to the top candidate gene TWIST1. Notably, Capture-C analysis revealed multiple cis interactions between the TWIST1 promoter and possible regulatory elements within the duplicated region. Modelling of the disease revealed an increased expression of HDAC9 and its neighbouring gene, TWIST1, in neural crest cells. We also identified decreased migration of iPSC-derived neural crest cells together with dysregulation of osteogenic differentiation in iPSC-affected mesenchymal stem cells. CONCLUSION: Our findings support the hypothesis that the 430 kb duplication is causative of the ARCND phenotype in this family and that deregulation of TWIST1 expression during craniofacial development can contribute to the phenotype.

Tympanic membrane perforations: a critical analysis of 1003 ears and proposal of a new classification based on pathogenesis.

PURPOSE: To present a large series ears with tympanic membrane perforations (TMP), to describe their characteristics, and to propose a new classification system based on the pathogenesis of TMP. METHODS: This cross-sectional study was conducted at a tertiary university hospital with 1003 ears (792 consecutive patients with TMP in at least 1 ear). Otoendoscopy and audiometry were performed. Perforation measurements and their locations were digitally assessed. TMP with no suggestive signs of previous retraction were classified as Group 1, and those with possible previous retraction were classified as Group 2. Signs of retraction previous to the TMP, symptom length, perforation size and location, status of the contralateral ear, and hearing status were compared. RESULTS: Group 1 comprised 63.5% of the included ears. Compared to Group 2, Group 1 presented a higher rate of central perforations (99% vs. 53%), a shorter duration of symptoms, smaller perforations (mean area: 18.5% vs. 41.4%), a higher rate of perforations in the anterior quadrants, better hearing levels (mean tritonal gap: 23.9 dB vs. 29.2 dB), and a lower rate of abnormal contralateral ears (28% vs. 66%). CONCLUSION: The classification of TMP into two groups based on signs of previous retractions is feasible and indicates two different levels of disease severity. While the group without previous signs of retraction comprises ears with more limited disease, membranes with previous retraction seem to show more severe disease and, consequently, a less functional middle ear.

Adaptations in Hippo-Yap signaling and myofibroblast fate underlie scar-free ear appendage wound healing in spiny mice.

Spiny mice (Acomys cahirinus) are terrestrial mammals that evolved unique scar-free regenerative wound-healing properties. Myofibroblasts (MFs) are the major scar-forming cell type in skin. We found that following traumatic injury to ear pinnae, MFs appeared rapidly in both Acomys and mouse yet persisted only in mouse. The timing of MF loss in Acomys correlated with wound closure, blastema differentiation, and nuclear localization of the Hippo pathway target protein Yap. Experiments in vitro revealed an accelerated PP2A-dependent dephosphorylation activity that maintained nuclear Yap in Acomys dermal fibroblasts (DFs) and was not detected in mouse or human DFs. Treatment of Acomys in vivo with the nuclear Yap-TEAD inhibitor verteporfin prolonged MF persistence and converted tissue regeneration to fibrosis. Forced Yap activity prevented and rescued TGF-ß1-induced human MF formation in vitro. These results suggest that Acomys evolved modifications of Yap activity and MF fate important for scar-free regenerative wound healing in vivo.

Anti-allergic property of 4,8-sphingadienine stereoisomers in vivo and in vitro model.

4,8-Sphingadienines (SD), metabolites of glucosylceramides (GlcCer), are sometimes determined as key mediators of the biological activity of dietary GlcCer, and cis/trans geometries of 4,8-SD have been reported to affect its activity. Since regulating excessive activation of mast cells seems an important way to ameliorate allergic diseases, this study was focused on cis/trans stereoisomeric-dependent inhibitory effects of 4,8-SD on mast cell activation. Degranulation of RBL-2H3 was inhibited by treatment of 4-cis-8-trans- and 4-cis-8-cis-SD, and their intradermal administrations ameliorated ear edema in passive cutaneous anaphylaxis reaction, but 4-trans-8-trans- and 4-trans-8-cis-SD did not. Although the activation of mast cells depends on the bound IgE contents, those stereoisomers did not affect IgE contents on RBL-2H3 cells after the sensitization of anti-TNP IgE. These results indicated that 4-cis-8-trans- and 4-cis-8-cis-SD directly inhibit the activation of mast cells. In conclusion, it was assumed that 4,8-SD stereoisomers with cis double bond at C4-position shows anti-allergic activity by inhibiting downstream pathway after activation by the binding of IgE to mast cells.

CXCL10+ peripheral activation niches couple preferred sites of Th1 entry with optimal APC encounter.

Correct positioning of T cells within infected tissues is critical for T cell activation and pathogen control. Upon tissue entry, effector T cells must efficiently locate antigen-presenting cells (APC) for peripheral activation. We reveal that tissue entry and initial peripheral activation of Th1 effector T cells are tightly linked to perivascular positioning of chemokine-expressing APCs. Dermal inflammation induces tissue-wide de novo generation of discrete perivascular CXCL10+ cell clusters, enriched for CD11c+MHC-II+ monocyte-derived dendritic cells. These chemokine clusters are "hotspots" for both Th1 extravasation and activation in the inflamed skin. CXCR3-dependent Th1 localization to the cluster micro-environment prolongs T-APC interactions and boosts function. Both the frequency and range of these clusters are enhanced via a T helper 1 (Th1)-intrinsic, interferon-gamma (IFNγ)-dependent positive-feedback loop. Thus, the perivascular CXCL10+ clusters act as initial peripheral activation niches, optimizing controlled activation broadly throughout the tissue by coupling Th1 tissue entry with enhanced opportunities for Th1-APC encounter.

Tacrolimus action pathways in an ointment base for hypertrophic scar prevention in a rabbit ear model

Abstract Background: Tacrolimus is used to prevent unaesthetic scars due to its action on fibroblast activity and collagen production modulation. Objectives: To evaluate the action pathways, from the histopathological point of view and in cytokine control, of tacrolimus ointment in the prevention of hypertrophic scars. Methods: Twenty-two rabbits were submitted to the excision of two 1-cm fragments in each ear, including the perichondrium. The right ear received 0.1% and 0.03% tacrolimus in ointment base twice a day in the upper wound and in the lower wound respectively. The left ear, used as the control, was treated with petrolatum. After 30 days, collagen fibers were evaluated using special staining, and immunohistochemistry analyses for smooth muscle actin, TGF-β and VEGF were performed. Results: The wounds treated with 0.1% tacrolimus showed weak labeling and a lower percentage of labeling for smooth muscle actin, a higher proportion of mucin absence, weak staining, fine and organized fibers for Gomori's Trichrome, strong staining and organized fibers for Verhoeff when compared to controls. The wounds treated with 0.03% tacrolimus showed weak labeling for smooth muscle actin, a higher proportion of mucin absence, strong staining for Verhoeff when compared to the controls. There was absence of TGF-β and low VEGF expression. Study limitations: The analysis was performed by a single pathologist. Second-harmonic imaging microscopy was performed in 2 sample areas of the scar. Conclusions: Both drug concentrations were effective in suppressing TGF-β and smooth muscle actin, reducing mucin, improving the quality of collagen fibers, and the density of elastic fibers, but only the higher concentration influenced elastic fiber organization.

IL-37 Targets TSLP-Primed Basophils to Alleviate Atopic Dermatitis.

Atopic dermatitis (AD) represents a severe global burden on physical, physiological and mental health. Innate immune cell basophils are essential for provoking allergic inflammation in AD. However, the roles of novel immunoregulatory cytokine IL-37 in basophils remain elusive. We employed in vitro co-culture of human basophils and human keratinocyte HaCaT cells and an in vivo MC903-induced AD murine model to investigate the anti-inflammatory mechanism of IL-37. In the in vitro model, IL-37b significantly decreased Der p1-induced thymic stromal lymphopoietin (TSLP) overexpression in HaCaT cells and decreased the expression of TSLP receptor as well as basophil activation marker CD203c on basophils. IL-37 could also reduce Th2 cytokine IL-4 release from TSLP-primed basophils ex vivo. In the in vivo model, alternative depletion of basophils ameliorated AD symptoms and significantly lowered the Th2 cell and eosinophil populations in the ear and spleen of the mice. Blocking TSLP alleviated the AD-like symptoms and reduced the infiltration of basophils in the spleen. In CRISPR/Cas9 human IL-37b knock-in mice or mice with direct treatment by human IL-37b antibody, AD symptoms including ear swelling and itching were significantly alleviated upon MC903 challenge. Notably, IL-37b presence significantly reduced the basophil infiltration in ear lesions. In summary, IL-37b could regulate the TSLP-mediated activation of basophils and reduce the release of IL-4. The results, therefore, suggest that IL-37 may target TSLP-primed basophils to alleviate AD.

Tacrolimus-loaded chitosan nanoparticles for enhanced skin deposition and management of plaque psoriasis.

Tacrolimus is a natural macrolide that exhibits an anti-proliferative action by T-lymphocytic cells inhibition. Hence, it was tested as a potential topical treatment to improve and control psoriatic plaques. In this study, for the first time the lipophilic tacrolimus in chitosan nanoparticles was used to achieve the desired response and dermal retention of the drug using a modified ionic gelation technique. The hydrophobic drug, tacrolimus, was successfully encapsulated into the synthesized positively-charged particles (140.8 nm ± 50.0) and EE of (65.5% ± 1.3). Local skin deposition of the drug was significantly enhanced with 82.0% ± 0.6 of the drug retained in the skin compared to 34.0% ± 0.9 from tarolimus® ointment. An outstanding response to the prepared formula was the enhanced hair growth rate in the treated animals, which can be considered an excellent sign of the skin recovery from the induced psoriatic plaques after only three days of treatment.

Clinical and Genetic Findings in 28 American Cocker Spaniels with Aural Ceruminous Gland Hyperplasia and Ectasia.

American Cocker Spaniels (ACSs) develop aural ceruminous gland hyperplasia and ectasia more often than dogs of other breeds. Data on the cause and development of these breed characteristic histopathological changes are lacking. We performed video-otoscopic examinations and dermatological work-up on 28 ACSs, obtained aural biopsies from each dog and assessed the statistical associations between the presence of ceruminous gland hyperplasia and ectasia and disease history, clinical or microbiological findings and underlying cause of otitis externa (OE). Histological lesions of ceruminous gland hyperplasia and ectasia were observed in aural biopsies from 6/13 clinically healthy ears and 13/15 ears with OE from 19/28 examined dogs. Nine of 28 dogs had histologically normal ceruminous glands (odds ratio [OR] 6.2, 95% confidence interval [CI] 1.1-36.6). Bacterial growth in microbiological culture of aural exudate (OR 14.1, 95% CI 2.1-95.3) was associated with ceruminous glandular changes, whereas previous history of OE, cutaneous findings or underlying allergies were not. Pedigree analysis and a genome-wide association study (GWAS) were performed on 18 affected and eight unaffected dogs based on histopathological diagnosis. While the GWAS indicated a tentative, but not statistically significant, association of ceruminous gland hyperplasia and ectasia with chromosome 31, a larger cohort is needed to confirm this preliminary result. Based on our results, ceruminous gland hyperplasia and ectasia may also precede clinical signs of OE in ACSs and a genetic aetiological component is likely Further studies with larger cohorts are warranted to verify our preliminary results.

Tacrolimus action pathways in an ointment base for hypertrophic scar prevention in a rabbit ear model.

BACKGROUND: Tacrolimus is used to prevent unaesthetic scars due to its action on fibroblast activity and collagen production modulation. OBJECTIVES: To evaluate the action pathways, from the histopathological point of view and in cytokine control, of tacrolimus ointment in the prevention of hypertrophic scars. METHODS: Twenty-two rabbits were submitted to the excision of two 1-cm fragments in each ear, including the perichondrium. The right ear received 0.1% and 0.03% tacrolimus in ointment base twice a day in the upper wound and in the lower wound respectively. The left ear, used as the control, was treated with petrolatum. After 30 days, collagen fibers were evaluated using special staining, and immunohistochemistry analyses for smooth muscle actin, TGF-ß and VEGF were performed. RESULTS: The wounds treated with 0.1% tacrolimus showed weak labeling and a lower percentage of labeling for smooth muscle actin, a higher proportion of mucin absence, weak staining, fine and organized fibers for Gomori's Trichrome, strong staining and organized fibers for Verhoeff when compared to controls. The wounds treated with 0.03% tacrolimus showed weak labeling for smooth muscle actin, a higher proportion of mucin absence, strong staining for Verhoeff when compared to the controls. There was absence of TGF-ß and low VEGF expression. STUDY LIMITATIONS: The analysis was performed by a single pathologist. Second-harmonic imaging microscopy was performed in 2 sample areas of the scar. CONCLUSIONS: Both drug concentrations were effective in suppressing TGF-ß and smooth muscle actin, reducing mucin, improving the quality of collagen fibers, and the density of elastic fibers, but only the higher concentration influenced elastic fiber organization.