ORCID Profile
0000-0003-2664-2098
Current Organisation
Monash University
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Publisher: Mary Ann Liebert Inc
Date: 11-2019
Publisher: Springer Science and Business Media LLC
Date: 22-05-2023
DOI: 10.1038/S43587-023-00421-1
Abstract: Coronavirus Disease 2019 (COVID-19) vaccination has resulted in excellent protection against fatal disease, including in older adults. However, risk factors for post-vaccination fatal COVID-19 are largely unknown. We comprehensively studied three large nursing home outbreaks (20–35% fatal cases among residents) by combining severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) aerosol monitoring, whole-genome phylogenetic analysis and immunovirological profiling of nasal mucosa by digital nCounter transcriptomics. Phylogenetic investigations indicated that each outbreak stemmed from a single introduction event, although with different variants (Delta, Gamma and Mu). SARS-CoV-2 was detected in aerosol s les up to 52 d after the initial infection. Combining demographic, immune and viral parameters, the best predictive models for mortality comprised IFNB1 or age, viral ORF7a and ACE2 receptor transcripts. Comparison with published pre-vaccine fatal COVID-19 transcriptomic and genomic signatures uncovered a unique IRF3 low/ IRF7 high immune signature in post-vaccine fatal COVID-19 outbreaks. A multi-layered strategy, including environmental s ling, immunomonitoring and early antiviral therapy, should be considered to prevent post-vaccination COVID-19 mortality in nursing homes.
Publisher: Springer Science and Business Media LLC
Date: 04-04-2018
DOI: 10.1038/S41598-018-24036-4
Abstract: The foregut endoderm gives rise to several organs including liver, pancreas, lung and thyroid with important roles in human physiology. Understanding which genes and signalling pathways regulate their development is crucial for understanding developmental disorders as well as diseases in adulthood. We exploited unique advantages of the zebrafish model to develop a rapid and scalable CRISPR/Cas-based mutagenesis strategy aiming at the identification of genes involved in morphogenesis and function of the thyroid. Core elements of the mutagenesis assay comprise bi-allelic gene invalidation in somatic mutants, a non-invasive monitoring of thyroid development in live transgenic fish, complementary analyses of thyroid function in fixed specimens and quantitative analyses of mutagenesis efficiency by Illumina sequencing of in idual fish. We successfully validated our mutagenesis-phenotyping strategy in experiments targeting genes with known functions in early thyroid morphogenesis ( pax2a , nkx2.4b ) and thyroid functional differentiation ( duox , duoxa , tshr ). We also demonstrate that duox and duoxa crispants phenocopy thyroid phenotypes previously observed in human patients with bi-allelic DUOX2 and DUOXA2 mutations. The proposed combination of efficient mutagenesis protocols, rapid non-invasive phenotyping and sensitive genotyping holds great potential to systematically characterize the function of larger candidate gene panels during thyroid development and is applicable to other organs and tissues.
Publisher: The Company of Biologists
Date: 15-05-2023
DOI: 10.1242/DEV.201023
Abstract: Thyroid tissue, the site of de novo thyroid hormone biosynthesis, is derived from ventral pharyngeal endoderm and defects in morphogenesis are a predominant cause of congenital thyroid diseases. The first molecularly recognizable step of thyroid development is the specification of thyroid precursors in anterior foregut endoderm. Recent studies have identified crucial roles of FGF and BMP signaling in thyroid specification, but the interplay between signaling cues and thyroid transcription factors remained elusive. By analyzing Pax2a and Nkx2.4b expression dynamics in relation to endodermal FGF and BMP signaling activities in zebrafish embryos, we identified a Pax2a-expressing thyroid progenitor population that shows enhanced FGF signaling but lacks Nkx2.4b expression and BMP signaling. Concurrent with upregulated BMP signaling, a subpopulation of these progenitors subsequently differentiates into lineage-committed thyroid precursors co-expressing Pax2a and Nkx2.4b. Timed manipulation of FGF/BMP activities suggests a model in which FGF signaling primarily regulates Pax2a expression, whereas BMP signaling regulates both Pax2a and Nkx2.4b expression. Our observation of similar expression dynamics of Pax8 and Nkx2-1 in mouse embryos suggests that this refined model of thyroid cell specification is evolutionarily conserved in mammals.
Publisher: MDPI AG
Date: 31-05-2022
DOI: 10.3390/V14061198
Abstract: We report two clusters of SARS-CoV-2 B.1.617.2 (Delta variant) infections in a group of 41 Indian nursing students who travelled from New Delhi, India, to Belgium via Paris, France. All students tested negative before departure and had a second negative antigen test upon arrival in Paris. Upon arrival in Belgium, the students were quarantined in eight different houses. Four houses remained COVID-free during the 24 days of follow-up, while all 27 residents of the other four houses developed an infection during quarantine, including the four residents who were fully vaccinated and the two residents who were partially vaccinated. Genome sequencing revealed two distinct clusters affecting one and three houses, respectively. In this group of students, vaccination status did not seem to prevent infection nor decrease the viral load. No severe symptoms were reported. Extensive contact tracing and 3 months of nationwide genomic surveillance confirmed that these outbreaks were successfully contained and did not contribute to secondary community transmission in Belgium. These clusters highlight the importance of repeated testing and quarantine measures among travelers coming from countries experiencing a surge of infections, as all infections were detected 6 days or more after arrival.
Publisher: Cold Spring Harbor Laboratory
Date: 19-12-2019
DOI: 10.1101/2019.12.19.880815
Abstract: Congenital hypothyroidism (CH) due to thyroid dysgenesis is a frequent congenital endocrine disorder for which the molecular mechanisms remain unresolved in the far majority of cases. This situation reflects in part our still limited knowledge about the mechanisms involved in the early steps of thyroid specification from the endoderm, in particular the extrinsic signaling cues that regulate foregut endoderm patterning. In this study, we used small molecules and genetic zebrafish models to characterize the role of various signaling pathways in thyroid specification. We treated zebrafish embryos during different developmental periods with small molecule compounds known to modulate the activity of Wnt signaling pathway and observed effects in thyroid, endoderm and cardiovascular development using whole mount in situ hybridization and transgenic fluorescent reporter models. We used an antisense morpholino to create a zebrafish acardiac model. For thyroid rescue experiments, BMP pathway induction in zebrafish embryos was obtained by using heatshock inducible transgenic lines. Interestingly, combined analyses of thyroid and cardiovascular development revealed that overactivation of Wnt signaling during early development leads to impaired thyroid specification concurrent with severe defects in the cardiac specification. When using a model of morpholino-induced blockage of cardiomyocyte differentiation, a similar correlation was observed, suggesting that defective signaling between cardiac mesoderm and endodermal thyroid precursors contributes to thyroid specification impairment. Rescue experiments through transient overactivation of BMP signaling could partially restore thyroid specification in models with defective cardiac development. Collectively, our results indicate that BMP signaling is critically required for thyroid cell specification and identify cardiac mesoderm as a likely source of BMP signals.
Publisher: EMBO
Date: 03-11-2020
Abstract: The thyroid gland regulates growth and metabolism via production of thyroid hormone in follicles composed of thyrocytes. So far, thyrocytes have been assumed to be a homogenous population. To uncover heterogeneity in the thyrocyte population and molecularly characterize the non‐thyrocyte cells surrounding the follicle, we developed a single‐cell transcriptome atlas of the region containing the zebrafish thyroid gland. The 6249‐cell atlas includes profiles of thyrocytes, blood vessels, lymphatic vessels, immune cells, and fibroblasts. Further, the thyrocytes show expression heterogeneity, including bimodal expression of the transcription factor pax2a . To validate thyrocyte heterogeneity, we generated a CRISPR/Cas9‐based pax2a knock‐in line that monitors pax2a expression in the thyrocytes. A population of pax2a ‐low mature thyrocytes interspersed in in idual follicles can be distinguished. We corroborate heterogeneity within the thyrocyte population using RNA sequencing of pax2a ‐high and pax2a ‐low thyrocytes, which demonstrates 20% differential expression in transcriptome between the two subpopulations. Our results identify and validate transcriptional differences within the presumed homogenous thyrocyte population.
Publisher: Cold Spring Harbor Laboratory
Date: 17-02-2019
DOI: 10.1101/551861
Abstract: Defects in embryonic development of the thyroid gland are a major cause for congenital hypothyroidism in human newborns but the underlying molecular mechanisms are still poorly understood. Organ development relies on a tightly regulated interplay between extrinsic signaling cues and cell intrinsic factors. At present, however, there is limited knowledge about the specific extrinsic signaling cues that regulate foregut endoderm patterning, thyroid cell specification and subsequent morphogenetic processes in thyroid development. To begin to address this problem in a systematic way, we used zebrafish embryos to perform a series of in vivo phenotype-driven chemical genetic screens to identify signaling cues regulating early thyroid development. For this purpose, we treated zebrafish embryos during different developmental periods with a panel of small molecule compounds known to manipulate the activity of major signaling pathways and scored phenotypic deviations in thyroid, endoderm and cardiovascular development using whole mount in situ hybridization and transgenic fluorescent reporter models. Systematic assessment of drugged embryos recovered a range of thyroid phenotypes including expansion, reduction or lack of the early thyroid anlage, defective thyroid budding as well as hypoplastic, enlarged or overtly disorganized presentation of the thyroid primordium after budding. Our pharmacological screening identified BMP and FGF signaling as key factors for thyroid specification and early thyroid organogenesis, highlight the importance of low Wnt activities during early development for thyroid specification and implicate drug-induced cardiac and vascular anomalies as likely indirect mechanisms causing various forms of thyroid dysgenesis. By integrating the outcome of our screening efforts with previously available information from other model organisms including Xenopus , chicken and mouse, we conclude that signaling cues regulating thyroid development appear broadly conserved across vertebrates. We therefore expect that observations made in zebrafish can inform mammalian models of thyroid organogenesis to further our understanding of the molecular mechanisms of congenital thyroid diseases.
Publisher: Cold Spring Harbor Laboratory
Date: 13-08-2020
DOI: 10.1101/2020.08.13.249540
Abstract: Thyroid tissue is the site for de novo synthesis of thyroid hormones which are essential for vertebrate development and growth. Defects in embryonic thyroid morphogenesis are a predominant cause for congenital thyroid diseases but the molecular pathomechanisms are incompletely understood. The first molecularly recognizable step of thyroid development is the specification of thyroid precursors at a defined position in the anterior foregut endoderm. While recent studies identified FGF and BMP pathways as critical signaling factors for thyroid specification, the interplay between extrinsic signaling cues and thyroid transcription factor expression remained elusive. Here, we used zebrafish embryos to decipher the dynamics of thyroid transcription factor induction in relation to FGF and BMP signaling activities in pharyngeal endoderm. We first identified a previously unrecognized endodermal thyroid progenitor cell population expressing Pax2a but not Nkx2.4b. This cell population is characterized by enhanced FGF signaling but initially lacks detectable BMP signaling. A subpopulation of Pax2a-expressing progenitors differentiates subsequently into thyroid lineage-committed precursor cells co-expressing Pax2a and Nkx2.4b. We next combined pharmacological approaches with genetic models permitting inhibition or ectopic overactivation of signaling pathways to timely manipulate FGF and BMP activities. These experiments support a model where FGF signaling primarily regulates Pax2a expression whereas BMP signaling has dual functions in regulation of both Pax2a and Nkx2.4b expression. Collectively, our data allow us to formulate a refined model of thyroid cell specification from foregut endoderm.
Publisher: Mary Ann Liebert Inc
Date: 03-2021
No related grants have been discovered for Benoit Haerlingen.