Project description:Esophageal atresia and tracheoesophageal fistula (EA/TEF) are relatively frequently occurring foregut malformations with a largely unknown etiology. EA/TEF is thought to have a strong genetic component and several genes have been proven to be involved in syndromic EA/TEF. However, it is not clear which biological processes or gene networks are disturbed. To gain more insight in the origin of the TEF, we aimed to examine and describe TEF composition using a combination of whole-genome transcription profiling and (immuno-) histochemical stainings. We hypothesized that such characterization of human TEFs provides insight in the molecular and mechanistic etiology of EA/TEF. Data analysis was carried out using BRB-array tools version 4.6.0 (October 2018) in combination with R version 3.5.1 (July 2018). For each probe set, the geometric mean of the hybridization intensities of all samples was calculated. The level of expression of each probe set was determined relative to this geometric mean and logarithmically transformed (on a base 2 scale) to ascribe equal weight to gene-expression levels with similar relative distances to the geometric mean.
Project description:Esophageal atresia (EA) with or without tracheoesophageal fistula (TEF) are tracheoesophageal (TE) birth defects which affect 1 in 3000 live births in the United States. EA occurs when the esophagus fails to form a continuous tube from the oral cavity to the stomach and TEF occurs when there is an abnormal connection between the trachea and esophagus. The etiology of EA/TEF arises when the common foregut tube fails to properly separate into the esophagus and respiratory tract during early embryogenesis. This process is essential for proper organ function and involves complex molecular and morphological processes. As part of a multi-institutional project aiming to identify genes causing tracheoesophageal defects, we identified two EA/TEF patients who presented with different mutations in SMAD6, a BMP signaling inhibitor. We used a CRISPR-based approach to knock down smad6 in frog embryos and observed separation defects of the esophagus and trachea, supporting the conclusion that SMAD6 mutations in humans may cause EA/TEF. To investigate the role of SMAD6 during human development, we used CRISPR to generate human pluripotent stem cell lines with loss-of-function alleles in SMAD6. The human foregut is comprised of an inner layer of endoderm-derived epithelium surrounded by mesenchyme, and it is not known if SMAD6 functions in either or both layers. To elucidate this, we investigated the role of SMAD6 in either foregut epithelium or mesenchyme, or both in combination. Our analysis of human SMAD6-/- tracheoesophageal epithelium and mesenchyme reveals an increase in BMP/TGFβ signaling, consistent with its role as a repressor of these pathways. We also observed patterning defects in both tissue types; SMAD6 mutant endoderm shows increased expression of distal gut tube markers and SMAD6 mutant mesenchyme shows increased expression of cardiac markers. Furthermore, we observed cell differentiation changes, where SMAD6-/- mesenchyme had decreased ability to form CD31-positive vasculature, as well as changes in genes involved in processes such as cell migration and extracellular matrix deposition, which are critical for mesenchyme morphogenesis and differentiation during the process of TE separation. Our results suggest SMAD6 mutations impact the identity and function of human engineered TE tissue. By identifying pathways significant for TE development during early embryogenesis, our results contribute to understanding how patient mutations cause congenital malformations.
Project description:Acquired benign tracheoesophageal fistula (TOF) is a rare medical condition that usually results from trauma, foreign bodies or granulomatous infections. This is an unusual presentation of a male patient with a history of laryngectomy who has had over a period of several years inappropriately and vigorously used valve cleaning brushes to clean tracheal secretions, which has led to the formation of a TOF. Due to the patient's obsessive habit, we could not manage him using conventional surgical methods. Instead, we opted for the placement of a salivary bypass tube, which yielded good results and recovery. To the best of our knowledge, no other case of similar aetiology has been published. We would like to highlight the importance of appropriate patient selection and education prior to performing a tracheoesophageal puncture to avoid developing life-threatening complications as demonstrated in our case report.