Hergo Holzhütter

About Hergo Holzhütter:
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SEEK ID: https://seek.lisym.org/people/54

Location:  Germany

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LiSyM-Krebs - Systemmedizinisches Forschungsnetz zur Früherkennung und Prävention von Leberkrebs

LiSyM-Krebs ist ein nationales Forschungsnetz zur Früherkennung und Prävention von Leberkrebs, das unter Verwendung des systemmedizinischen Forschungsansatzes die komplexen, dynamischen Prozesse der Krankheitsprogression analysiert, um ausgehend von den Erkenntnissen aus dem Forschungsnetz LiSyM die Entstehung von Leberkrebs besser zu verstehen, vorherzusagen und im besten Fall sogar zu verhindern. LiSyM-Krebs setzt die erfolgreichen Forschungsaktivitäten der BMBF-Vorgängerprogramme ...

Projects: LiSyM-Krebs Partnering, Forschungsnetzwerk LiSyM-Krebs, SMART-NAFLD, DEEP-HCC network, C-TIP-HCC network

Web page: Not specified

LiSyM: Liver Systems Medicine

Liver Systems Medicine : striving to develop non-invasive methods for diagnosing and treating NAFLD by combining mathematical modeling and biological research. LiSyM, is a multidisciplinary research network, in which molecular and cell biologists, clinical researchers, pharmacologists and experts in mathematical modeling examine the liver in its entirety. LiSyM research focuses on the metabolic liver disease non-alcoholic fatty liver disease (NAFLD), which includes non-alcoholic steatohepatitis ...

Projects: LiSyM Core Infrastructure and Management (LiSyM-PD), LiSyM Pillar I: Early Metabolic Injury (LiSyM-EMI), LiSyM Pillar II: Chronic Liver Disease Progression (LiSyM-DP), LiSyM Pillar III: Regeneration and Repair in Acute-on-Chronic Liver Failure (LiSyM-ACLF), LiSyM Pillar IV: Liver Function Diagnostics (LiSyM-LiFuDi), Model Guided Pharmacotherapy In Chronic Liver Disease (LiSyM-MGP), Molecular Steatosis - Imaging & Modeling (LiSyM-MSIM), The Hedgehog Signalling Pathway (LiSyM-JGMMS), Multi-Scale Models for Personalized Liver Function Tests (LiSyM-MM-PLF), LiSyM PALs, Project Management PTJ, LiSyM network, LiSyM Scientific Leadership Team (LiSyM-LT)

Web page: https://www.lisym.org/

LiSyM network

This comprises the whole LiSyM network

Programme: LiSyM: Liver Systems Medicine

Public web page: http://www.lisym.org

Start date: 1st Jan 2016

LiSyM-Krebs Partnering

This generic project is intended to be a forum for all LiSyM partner and external stakeholders interested in participating in the BMBF initiative LiSyM-Krebs.

Programme: LiSyM-Krebs - Systemmedizinisches Forschungsnetz zur Früherkennung und Prävention von Leberkrebs

Public web page: https://www.ptj.de/projektfoerderung/gesundheitsforschung/lisym-krebs

LiSyM Pillar IV: Liver Function Diagnostics (LiSyM-LiFuDi)

Disorders of the liver show up through changes in blood tests. These blood tests indicate markers for events taking place in the liver. Usually studies of liver tissue cannot be performed: as liver samples would need to be obtained through a liver biopsy, and this procedure is not without risk, therefore these samples are usually unavailable. Complex metabolism models based on existing and new scientific data can simulate changes in the liver caused by disease. They often reveal unknown relationships ...

Programme: LiSyM: Liver Systems Medicine

Public web page: http://www.lisym.org/our-work/pillar-research/the-liver-is-very-patient

Start date: 1st Jan 2016

LiSyM Scientific Leadership Team (LiSyM-LT)

Day-to-day science within the LiSyM is overseen and directed by the the LiSyM Scientific Leadership Team. This coordination team comprises the pillar coordinators and additional LiSyM members, and ensures smooth interaction between multi-skilled groups, often working in different institutions and across significant distances within Germany.

Programme: LiSyM: Liver Systems Medicine

Public web page: http://www.lisym.org/who-we-are

Molecular Steatosis - Imaging & Modeling (LiSyM-MSIM)

Dr. Nachiket Vartak (TU University, Dortmund) investigates the role of a particular protein - the GTPase Rab18 - in initiating NAFLD. He tries to influence Rab18 pharmacologically so that NAFLD is not initiated. Vartak also analyzes how bile acids leave the liver. He hopes to find ways to improve the flow of bile in a liver with dysfunctional bile flow.

Programme: LiSyM: Liver Systems Medicine

Public web page: http://www.lisym.org/our-work/junior-group/the-protein-rab18

Start date: 1st Jan 2016

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Effect of Post-mortem Interval and Perfusion on the Biophysical Properties of ex vivo Liver Tissue Investigated Longitudinally by MRE and DWI.
LiSyM Pillar IV: Liver Function Diagnostics (LiSyM-LiFuDi)

Abstract (Expand)

Structural changes of soft tissues on the cellular level can be characterized by histopathology, but not longitudinally in the same tissue. Alterations of cellular structures and tissue matrix are … associated with changes in biophysical properties which can be monitored longitudinally by quantitative diffusion-weighted imaging (DWI) and magnetic resonance elastography (MRE). In this work, DWI and MRE examinations were performed in a 0.5-Tesla compact scanner to investigate longitudinal changes in water diffusivity, stiffness and viscosity of ex-vivo rat livers for up to 20 h post-mortem (pm). The effect of blood on biophysical parameters was examined in 13 non-perfused livers (containing blood, NPLs) and 14 perfused livers (blood washed out, PLs). Changes in cell shape, cell packing and cell wall integrity were characterized histologically. In all acquisitions, NPLs presented with higher shear-wave speed (c), higher shear-wave penetration rate (a) and smaller apparent-diffusion-coefficients (ADCs) than PL. Time-resolved analysis revealed three distinct phases: (i) an initial phase (up to 2 h pm) with markedly increased c and a and reduced ADCs; (ii) an extended phase with relatively stable values; and (iii) a degradation phase characterized by significant increases in a (10 h pm in NPLs and PLs) and ADCs (10 h pm in NPLs, 13 h pm in PLs). Histology revealed changes in cell shape and packing along with decreased cell wall integrity, indicating tissue degradation in NPLs and PLs 10 h pm. Taken together, our results demonstrate that the biophysical properties of fresh liver tissue rapidly change within 2 h pm, which seems to be an effect of both cytotoxic edema and vascular blood content. Several hours later, disruption of cell walls resulted in higher water diffusivity and wave penetration. These results reveal the individual contributions of vascular components and cellular integrity to liver elastography and provide a biophysical, imaging-based fingerprint of liver tissue degradation.

Authors: K. Garczynska, H. Tzschatzsch, S. Assili, A. A. Kuhl, A. Hackel, E. Schellenberger, N. Berndt, H. G. Holzhutter, J. Braun, I. Sack, J. Guo

Date Published: 20th Aug 2021

Publication Type: Journal

Computational Hypothesis: How Intra-Hepatic Functional Heterogeneity May Influence the Cascading Progression of Free Fatty Acid-Induced Non-Alcoholic Fatty Liver Disease (NAFLD).
LiSyM Pillar IV: Liver Function Diagnostics (LiSyM-LiFuDi)

Abstract (Expand)

Non-Alcoholic Fatty Liver Disease (NAFLD) is the most common type of chronic liver disease in developed nations, affecting around 25% of the population. Elucidating the factors causing NAFLD in individual … patients to progress in different rates and to different degrees of severity, is a matter of active medical research. Here, we aim to provide evidence that the intra-hepatic heterogeneity of rheological, metabolic and tissue-regenerating capacities plays a central role in disease progression. We developed a generic mathematical model that constitutes the liver as ensemble of small liver units differing in their capacities to metabolize potentially cytotoxic free fatty acids (FFAs) and to repair FFA-induced cell damage. Transition from simple steatosis to more severe forms of NAFLD is described as self-amplifying process of cascading liver failure, which, to stop, depends essentially on the distribution of functional capacities across the liver. Model simulations provided the following insights: (1) A persistently high plasma level of FFAs is sufficient to drive the liver through different stages of NAFLD; (2) Presence of NAFLD amplifies the deleterious impact of additional tissue-damaging hits; and (3) Coexistence of non-steatotic and highly steatotic regions is indicative for the later occurrence of severe NAFLD stages.

Authors: H. G. Holzhutter, N. Berndt

Date Published: 5th Mar 2021

Publication Type: Journal

How histopathologic changes in pediatric nonalcoholic fatty liver disease influence in vivo liver stiffness.
LiSyM Pillar IV: Liver Function Diagnostics (LiSyM-LiFuDi)

Abstract (Expand)

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in children and adolescents. About 30% of patients with NAFLD progress to the more severe condition of nonalcoholic … steatohepatitis (NASH), which is typically diagnosed using liver biopsy. Liver stiffness (LS) quantified by elastography is a promising imaging marker for the noninvasive assessment of NAFLD and NASH in pediatric patients. However, the link between LS and specific histopathologic features used for clinical staging of NAFLD is not well defined. Furthermore, LS data reported in the literature can vary greatly due to the use of different measurement techniques. Uniquely, time-harmonic elastography (THE) based on ultrasound and magnetic resonance elastography (MRE) use the same mechanical stimulation, allowing us to compare LS in biopsy-proven NAFLD previously determined by THE and MRE in 67 and 50 adolescents, respectively. In the present work, we analyzed the influence of seven distinct histopathologic features on LS, including septal infiltration, bridging fibrosis, pericellular fibrosis, hepatocellular ballooning, portal inflammation, lobular inflammation, and steatosis. LS was highly correlated with periportal and lobular fibrosis as well as hepatocellular ballooning while no independent association was found for inflammation and steatosis. Based on this analysis, we propose a composite elastography score (CES) which includes the four key histopathologic features identified as mechanically relevant. Interestingly, CES-relevant histopathologic features were associated with zonal distribution patterns of pediatric NAFLD. Mechano-structural changes associated with NAFLD progression can be histopathologically staged using the CES, which is easily determined noninvasively based on LS measured by time-harmonic elastography.

Authors: C. A. Hudert, H. Tzschatzsch, B. Rudolph, C. Loddenkemper, H. G. Holzhutter, L. Kalveram, S. Wiegand, J. Braun, I. Sack, J. Guo

Date Published: 17th Jan 2021

Publication Type: Journal

Regulation of the cytochrome P450 epoxyeicosanoid pathway is associated with distinct histologic features in pediatric non-alcoholic fatty liver disease.
LiSyM Pillar IV: Liver Function Diagnostics (LiSyM-LiFuDi)

Abstract (Expand)

Non-alcoholic fatty liver disease (NAFLD) is a significant health burden in obese children for which there is currently no specific therapy. Preclinical studies indicate that epoxyeicosanoids, a class … of bioactive lipid mediators that are generated by cytochrome P450 (CYP) epoxygenases and inactivated by the soluble epoxide hydrolase (sEH), play a protective role in NAFLD. We performed a comprehensive lipidomics analysis using liver tissue and blood samples of 40 children with NAFLD. Proteomics was performed to determine CYP epoxygenase and sEH expressions. Hepatic epoxyeicosanoids significantly increased with higher grades of steatosis, while their precursor PUFAs were unaltered. Concomitantly, total CYP epoxygenase activity increased while protein level and activity of sEH decreased. In contrast, hepatic epoxyeicosanoids showed a strong decreasing trend with higher stages of fibrosis, accompanied by a decrease of CYP epoxygenase activity and protein expression. These findings suggest that the CYP epoxygenase/sEH pathway represents a potential pharmacologic target for the treatment of NAFLD.

Authors: L. Kalveram, W. H. Schunck, M. Rothe, B. Rudolph, C. Loddenkemper, H. G. Holzhutter, S. Henning, P. Bufler, M. Schulz, D. Meierhofer, I. W. Zhang, K. H. Weylandt, S. Wiegand, C. A. Hudert

Date Published: 4th Jan 2021

Publication Type: Journal

Changes in Liver Mechanical Properties and Water Diffusivity During Normal Pregnancy Are Driven by Cellular Hypertrophy.
LiSyM Pillar IV: Liver Function Diagnostics (LiSyM-LiFuDi)

Abstract (Expand)

During pregnancy, the body's hyperestrogenic state alters hepatic metabolism and synthesis. While biochemical changes related to liver function during normal pregnancy are well understood, … pregnancy-associated alterations in biophysical properties of the liver remain elusive. In this study, we investigated 26 ex vivo fresh liver specimens harvested from pregnant and non-pregnant rats by diffusion-weighted imaging (DWI) and magnetic resonance elastography (MRE) in a 0.5-Tesla compact magnetic resonance imaging (MRI) scanner. Water diffusivity and viscoelastic parameters were compared with histological data and blood markers. We found livers from pregnant rats to have (i) significantly enlarged hepatocytes (26 +/- 15%, p < 0.001), (ii) increased liver stiffness (12 +/- 15%, p = 0.012), (iii) decreased viscosity (-23 +/- 14%, p < 0.001), and (iv) increased water diffusivity (12 +/- 11%, p < 0.001). In conclusion, increased stiffness and reduced viscosity of the liver during pregnancy are mainly attributable to hepatocyte enlargement. Hypertrophy of liver cells imposes fewer restrictions on intracellular water mobility, resulting in a higher hepatic water diffusion coefficient. Collectively, MRE and DWI have the potential to inform on structural liver changes associated with pregnancy in a clinical context.

Authors: K. Garczynska, H. Tzschatzsch, A. A. Kuhl, A. S. Morr, L. Lilaj, A. Hackel, E. Schellenberger, N. Berndt, H. G. Holzhutter, J. Braun, I. Sack, J. Guo

Date Published: 17th Dec 2020

Publication Type: Journal

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