Disruption of THY-1 signaling in alveolar lipofibroblasts in experimentally induced congenital diaphragmatic hernia

Purpose

Pulmonary hypoplasia (PH), characterized by alveolar immaturity, remains the main cause of neonatal mortality and long-term morbidity in infants with congenital diaphragmatic hernia (CDH). Lipid-containing interstitial fibroblasts (LIFs) are critically important for normal alveolar development. Thymocyte antigen 1 (Thy-1) is a highly expressed cell-surface protein in this specific subset of lung fibroblasts, which plays a key role in fetal alveolarization by coordinating the differentiation and lipid homeostasis of alveolar LIFs. Thy-1 increases the lipid content of LIFs by upregulation of adipocyte differentiation-related protein (ADRP), a lipogenic molecular marker characterizing pulmonary LIFs. Thy-1 ^?/? mice further show impaired alveolar development with reduced proliferation of pulmonary LIFs, resulting in a PH-similar phenotype. We hypothesized that pulmonary Thy-1 signaling is disrupted in experimentally induced CDH, which may has an adverse effect on the lipid content of alveolar LIFs.

Methods

Timed-pregnant Sprague–Dawley rats were treated with either 100 mg nitrofen or vehicle on embryonic day 9.5 (E9.5). Fetuses were killed on E21.5, and lungs were divided into controls (n = 14) and CDH-associated PH (n = 14). Pulmonary gene expression levels of Thy-1 and ADRP were assessed by quantitative real-time PCR. ADRP immunohistochemistry and oil-red-O staining were used to localize alveolar LIF expression and lipid droplets. Immunofluorescence double staining for Thy-1 and oil-red-O was performed to evaluate Thy-1 expression and lipid content in alveolar LIFs.

Results

Radial alveolar count was significantly reduced in CDH-associated PH with significant downregulation of pulmonary Thy-1 and ADRP mRNA expression compared to controls. ADRP immunoreactivity and lipid droplets were markedly diminished in alveolar interstitial cells, which coincided with decreased alveolar LIF expression in CDH-associated PH compared to controls. Confocal laser scanning microscopy confirmed markedly decreased Thy-1 expression and lipid content in alveolar LIFs of CDH-associated PH compared to controls.

Conclusion

Our study provides strong evidence that disruption of pulmonary Thy-1 signaling results in reduced lipid droplets in alveolar LIFs and may thus contribute to PH in the nitrofen-induced CDH model. Treatment modalities aimed at increasing lipid content in alveolar LIFs may therefore have a therapeutic potential in attenuating CDH-associated PH.     

Challenges in Patient Enrollment and Retention in Clinical Studies for Alcoholic Hepatitis: Experience of the TREAT Consortium

The TREAT Consortium has carried out clinical studies on alcoholic hepatitis (AH) for over 4 years. We encountered problems with participant recruitment, retention, and eligibility for specific protocols. To improve our ability to carry out such trials, we reviewed recruitment screening logs, end of study logs, and surveyed study coordinators to learn the reasons for missing patients, why patients declined enrollment, and the number of patients eligible for treatment trials. Associations of the recruited subjects’ demographics with their adherence to follow‐up appointments were examined. Three hundred eight‐seven patients (AH and heavy drinking controls) were enrolled in the observational study, and 55 AH patients were recruited into treatment trials. About half of patients identified with AH could not be recruited; no specific reason could be determined for about two‐thirds of these. Among the patients who gave a reason for not participating, the most common reasons were feeling too sick to participate, desire to concentrate on abstinence, and lack of interest in research. Approximately a quarter of the AH patients met eligibility criteria for treatment trials for moderate or severe AH and we were able to recruit half to two‐thirds of those eligible. Approximately 35% of participants in the observational study returned for both 6‐ and 12‐month follow‐up visits. We did not identify biopsychosocial or demographic correlates of retention in the study. This analysis revealed that attempts at recruitment into trials for AH miss some subjects because of structural issues surrounding their hospital admission, and encounter a high rate of patient refusal to participate. Nonetheless, more than half of the patients who met the eligibility criteria for moderate or severe AH were entered into clinical trials. Retention rates for the observational study are relatively low. These findings need to be accounted for in clinical trial design and power analysis.     

Evaluation of third molar maturity index (I3M) in assessing the legal age of subjects in an Indian Goan population

India affords special laws and exemptions to minors under the criminal, marriage, labour and administrative laws. Many perpetrators claim to be a minor in the hope of a lenient trial and verdict. The authorities often rely upon forensic experts to provide evidence-based reports. The third molar can be relied upon in the assessment of legal age as it continues developing into the early twenties. The method established by Cameriere et al in 2008 provides an objective method for the accurate evaluation of legal age. Our study was designed to analyze and validate the efficacy of Third Molar Maturity index (I3M) in an Indian Goan population and compare it to published literature. 542 panoramic radiographs of subjects aged between 14 and 24 years were evaluated. The chronologic age increased as I3M reduced. There was no evidence of sexual dimorphism in third molar development across various I3M classes (p>0.05). Receiver Operator Characteristic Curve was plotted for males and females which showed an Area Under Curve of 0.95 (95% CI, 0.92-0.97) and 0.93 (95% CI, 0.90-0.96) respectively. 2x2 contingency tables were used to test the performance of various I3M cut-off values ranging from I3M=0.02 to 0.14. I3M = 0.08 showed the most promising results for the assessment of legal age. Our study achieved a high degree of accurate classification of 0.90 and 0.88 for males and females respectively. Results demonstrate a sensitivity of 0.899 and 0.854 and specificity of 0.90 and 0.93 for males and females respectively. The positive likelihood ratios were 9.88 and 12.44 while negative likelihood ratio was 0.11 and 0.15 for males and females respectively. A favourable Bayes Post Test Probability of 0.95 was noted for both males and females. These results allow us to strongly recommend the use of I3M for the assessment of legal age in an Indian Goan population.     

New observations on the pathogenesis of multiple intestinal atresias

It has been suggested that multiple intestinal atresias result from multiple ischemic infarctions of the intestinal tract. We have studied surgical material from 59 neonates with intestinal atresias seen at our hospital between 1975 and 1986. Forty (68%) patients had single intestinal atresias and 19 (32%) had multiple atresias. There were seven cases of hereditary multiple atresias seen in three families and 12 cases of nonhereditary multiple atresias. All hereditary cases had numerous type I or type II gastrointestinal atresias but none had type IIIa atresia. Six of the seven hereditary cases had multiple atresias in the small as well as large bowel. The 12 patients with nonhereditary atresias had various types of atresias but mesenteric or intestinal interruption was observed in only two patients. All patients with hereditary multiple intestinal atresias showed identical microscopic appearances in the small and large intestine, consisting of sieve-like multiple lumina, each surrounded by its own mucosa and muscularis mucosae but sharing a common muscle coat. There was no evidence of lanugo, bile pigments, or squames within the lumen distal to atretic segments in any of these patients. Six nonhereditary cases who had multiple septal atresias affecting only the small bowel demonstrated essentially similar lesions on microscopic examination as seen in hereditary cases. There was no evidence of arterial occlusion in the mesentery and lanugo, bile pigments, and squames could not be found distally in the intestinal contents in any of these cases. These pathologic findings suggest that all cases of hereditary multiple intestinal atresias and some cases of nonhereditary multiple intestinal atresias are a consequence of a malformative process of the gastrointestinal tract rather than an ischemic process.