Biology subjects

Hackert, T.

Publications and source records attributed to Hackert, T..

4 recordsLinked to original sources

bioRxiv2021

Hepatocyte-specific activity of TSC22D4 triggers progressive NAFLD by impairing mitochondrial function

ObjectiveFibrotic organ responses have recently been identified as long-term complication in diabetes. Indeed, insulin resistance and aberrant hepatic lipid accumulation represent driving features of progressive non-alcoholic fatty liver disease (NAFLD), ranging from simple steatosis and non-alcoholic steatohepatitis (NASH) to fibrosis. Effective pharmacological regimens to stop progressive liver disease are still lacking to-date. MethodsBased on our previous discovery of transforming growth factor beta-like stimulated clone (TSC)22D4 as a key driver of insulin resistance and glucose intolerance in obesity and type 2 diabetes, we generated a TSC22D4-hepatocyte specific knockout line (TSC22D4-HepaKO) and exposed mice to control or NASH diet models. Mechanistic insights were generated by metabolic phenotyping and single cell liver sequencing. ResultsHepatic TSC22D4 expression was significantly correlated with markers of liver disease progression and fibrosis in both murine and human livers. Indeed, hepatic TSC22D4 levels were elevated in human NASH patients as well as in several murine NASH models. Specific genetic deletion of TSC22D4 in hepatocytes led to reduced liver lipid accumulation, improvements in steatosis and inflammation scores and decreased apoptosis in mice. Single cell RNA sequencing revealed a distinct gene signature identifying an upregulation of mitochondrial-related processes. An enrichment of genes involved in the TCA cycle, mitochondrial organization, and triglyceride metabolism underscored the hepatocyte-protective phenotype and overall decreased liver damage as seen in mouse models. ConclusionsTogether, our data uncover a new connection between targeted depletion of TSC22D4 and intrinsic metabolic processes in progressive liver disease. Cell-specific reduction of TSC22D4 improves hepatic steatosis, inflammation and promotes hepatocyte survival thus paving the way for further preclinical therapy developments.

physiology↗

bioRxiv2021

GATA4 and GATA6 loss-of-expression is associated with extinction of the classical programme and poor outcome in pancreatic ductal adenocarcinoma

ObjectiveGATA6 is a master regulator of pancreatic differentiation and a key regulator of the classical phenotype in pancreatic ductal adenocarcinoma (PDAC). Low GATA6 expression is associated with poor patient outcome. GATA4 is the second most expressed GATA factor in the pancreas. The aim was to assess whether, and how, GATA4 contributes to PDAC phenotype and to analyze the association of expression with clinical outcome. DesignWe analyzed PDAC transcriptomic data, stratifying cases according to GATA4 and GATA6 expression, and identified differentially expressed genes and pathways. A multicenter TMA study to assess GATA4 and GATA6 expression in PDAC samples (n=745) from patients undergoing tumour resection was performed using immunohistochemistry with antibodies of validated specificity. GATA4 and GATA6 levels were dichotomized into high/low categorical variables; association with outcome was assessed using univariable and multivariable Cox regression models. ResultsSubtype classification using transcriptomic data revealed that GATA4 mRNA is enriched in classical, compared to basal-like tumours. We classified samples in 4 groups as high/low for GATA4 and GATA6. Reduced expression of GATA4 did not have a major transcriptional impact. However, concomitant low expression of GATA4 enhanced the transcriptomic effects of GATA6 low expression. Reduced expression of both proteins in tumours was associated with the worst patient survival. GATA4 and GATA6 expression significantly decreased in metastases and negatively correlated with basal markers. ConclusionsOur analyses uncover a cooperative interaction between GATA4 and GATA6 to maintain the classical PDAC phenotype and provide compelling clinical rationale for assessing their expression as biomarkers of poor prognosis. SUMMARY BOXO_ST_ABSWhat is already known about this subject?C_ST_ABS- Patients with classical-type PDAC have a better outcome - Retrospective analyses suggest that classical-type PDAC is more sensitive to 5-FU-based chemotherapy - GATA6 is a surrogate biomarker of classical tumours and its expression is associated with better survival - GATA4 and GATA6 have overlapping and unique functions during pancreatic and gastrointestinal development What are the new findings?- Tumours displaying only low GATA4 expression have a transcriptomic profile similar to those with preserved expression of both transcription factors - Combined low expression of GATA4 and GATA6 has the highest transcriptomic impact - In a large multicenter tissue microarray study, patients with tumours showing low expression of both GATA4 and GATA6 have the worst overall survival - Low expression of GATA4 and GATA6 is an independent predictor of survival in patients with resectable PDAC - GATA4 levels are down-regulated in liver metastases and are negatively correlated with basal markers such as KRT5/6, KRT14, and TP63 How might it impact on clinical practice in the foreseeable future?- The combined assessment of GATA4 and GATA6 expression may improve prognostic stratification of patients with PDAC - Prospective studies should confirm whether GATA4 and GATA6 expression is also predictive of response to chemotherapy in PDAC patients

cancer biology↗

bioRxiv2021

Langerhans islets induce anti-tumor immunity at the expense of glycemic control and predict chemotherapy response in pancreatic cancer

Induction of anti-tumor immunity in pancreatic ductal adenocarcinoma (PDA) is an unresolved challenge. Systematic investigation of the microenvironment of primary pancreatic tumors revealed a role of endocrine Langerhans islets in the coordination of immune activation. We found that intratumoral {beta}-cells, regulated via STAT3, secrete C-C motif chemokine ligand 27 (CCL27) and thereby promote a TH1 phenotype in the microenvironment resulting in an enhanced T cell infiltration and prolonged patient survival. The local effect can be abrogated in a patient-based human explant model by inhibition of the CCL27 receptor CCR10. This defense mechanism is paralleled by an impaired metabolic function of Langerhans islets with reduced insulin levels resulting in a dysregulation of glycemic control in patients. Based on these findings, screening of PDA cases (n= 2264) led to the identification of type 2 diabetes mellitus (T2DM) and extractable glycated haemoglobin (HbA1c) levels as response markers for neoadjuvant chemotherapy with fluorouracil, leucovorin, irinotecan and oxaliplatin (FOLFIRINOX). Collectively these data provide insights into the interconnection of T2DM and PDA, and link declining glycemic control to therapeutic efficacy, which can be utilized as a tool for clinical decision-making and improve patient management.

cancer biology↗

bioRxiv2021

Towards 3D-Bioprinting of an Endocrine Pancreas: A Building-Block Concept for Bioartificial Insulin-Secreting Tissue

Background & Aims3D-Bioprinting of an endocrine pancreas is a promising future curative treatment for selected patients with insulin secretion deficiency. In this study we present an end-to-end integrative, scalable concept extending from the molecular to the macroscopic level. MethodsA hybrid scaffold device was manufactured by 3D-(bio)printing. INS-1 cells with/without endothelial cells were bioprinted in gelatin methacrylate blend hydrogel. Polycaprolactone was 3D-printed and heparin-functionalized as structural scaffold component. In vitro evaluation was performed by viability and growth assays, total mRNA sequencing, and glucose-stimulated insulin secretion. In vivo, xenotransplantation to fertilized chicken eggs was used to investigate vascularization and function, and finite element analysis modeling served to detect boundary conditions and applicability for human islets of Langerhans. ResultsInsulin-secreting pseudoislets were formed and resulted in a viable and proliferative experimental model. Transcriptomics revealed upregulation of proliferative and {beta}-cell-specific signaling cascades, downregulation of apoptotic pathways, and overexpression of extracellular matrix proteins and VEGF induced by pseudoislet formation and 3D culture. Co-culture with human endothelial cells created a natural cellular niche resulting in enhanced insulin response after glucose stimulation. Survival and function of the pseudoislets after explantation and extensive scaffold vascularization of both the hydrogel and heparinized polycaprolactone components were demonstrated in ovo. Computer simulations of oxygen, glucose, and insulin flows were used to evaluate scaffold architectures and Langerhans islets at a future transplantation site along neurovascular structures. ConclusionA defined end-to-end process for multidisciplinary bioconvergence research on a bioartificial endocrine pancreas was developed. A modular, patient-specific device architecture is proposed for future research studies.

bioengineering↗