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Dive into the research topics where Tim Zimmermann is active.

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Featured researches published by Tim Zimmermann.


Transplant International | 2007

Efficacy of an escalating dose regimen of pegylated interferon α-2a plus ribavirin in the early phase of HCV reinfection after liver transplantation

Tim Zimmermann; Wulf O. Böcher; Stefan Biesterfeld; Anca Zimmermann; Stefan Kanzler; Gertrud Greif-Higer; Ana Paula Barreiros; Mf Sprinzl; Marcus A. Wörns; Ansgar W. Lohse; Christian Mönch; Gerd Otto; Peter R. Galle; Marcus Schuchmann

We evaluated the safety and efficacy of an escalating dose regimen of pegylated interferon α‐2a (PEG‐IFNα‐2a) and ribavirin in the early phase of recurrent hepatitis C after orthotopic liver transplantation (OLT). In this prospective study, 26 patients transplanted for hepatitis C virus cirrhosis with recurrent hepatitis C were treated 3.4 ± 3.6 months after OLT and compared with an untreated historical control. PEG‐IFNα‐2a was initiated as monotherapy, following stepwise dose escalation up to 180 μg/week and the addition of ribavirin up to 1200 mg/day or maximally tolerated doses for 48 weeks. In the intent‐to‐treat analysis, 38% showed an early virological response (EVR), 35% an end of treatment response (ETR) and 19% a sustained virological response (SVR). SVR was associated with EVR (P = 0.0001) and cumulative PEG‐IFNα‐2a dose (P = 0.04). There was no significant histological improvement compared with untreated patients. There were no treatment‐related serious adverse events. Adverse events included leucopenia (77%) and thrombocytopenia (46%). Three patients discontinued therapy due to side effects, fourteen were nonresponders and four relapsers. Treatment with PEG‐IFNα‐2a and ribavirin in the acute phase of post‐transplant recurrent hepatitis C yielded an EVR of 38% and an SVR of 19%. The combination was safe and well tolerated.


Transplantation | 2010

Early steroid-free immunosuppression with FK506 after liver transplantation: long-term results of a prospectively randomized double-blinded trial.

Nina Weiler; Ina Thrun; M. Hoppe-Lotichius; Tim Zimmermann; Irene Kraemer; Gerd Otto

Background. The aim of this prospective, randomized, double-blinded, placebo-controlled single center study was to evaluate an early steroid-free immunosuppression in liver transplant patients. Methods. From March 2000 to October 2004, 110 patients were included. All patients received tacrolimus and steroids during the first 2 weeks after orthotopic liver transplantation (OLT). Thereafter, patients in the steroid group (n=54) received steroids and the remaining 56 a placebo. After 6 months, the immunosuppression for all was steroid free. Thirty patients were hepatitis C positive. Five years after inclusion, patient survival, organ survival, steroid side effects, and recirrhosis in hepatitis C virus (HCV) patients were reevaluated. Results. After 5 years, the following parameters were comparable in both groups: patient survival (P=0.236), organ survival (P=0.509), and acute rejections (P=0.409). Steroid-free immunosuppression lead to a higher rate of chronic rejections (P=0.023). Six months after OLT, there was a difference in rates of posttransplant diabetes mellitus (PTDM) (P=0.024) and hypercholesterolemia (P=0.002). However, 5 years after OLT, there was no difference in hypertension (P=0.647), PTDM (P=0.453), hypercholesterolemia (P=0.412), and osteoporosis (P=0.624). In HCV patients, we could not find any differences in patient survival (P=0.096), organ survival (P=0.424), time free from recirrhosis (P=0.647). The rate of recirrhosis was influenced by steroid bolus therapy (P=0.01) but not by avoiding continuous steroid therapy. Conclusions. Early tapering down of steroids to a tacrolimus monotherapy is possible with comparable acute rejection rates. During steroid therapy, PTDM and hypercholesterolemia are cumulative. These side effects are reversible. The recirrhosis in HCV patients is not influenced by continuous steroid therapy but more frequent in HCV patients receiving a steroid bolus therapy.


Journal of Hepatology | 2011

Ablation of c-FLIP in hepatocytes enhances death-receptor mediated apoptosis and toxic liver injury in vivo.

Jörn M. Schattenberg; Tim Zimmermann; Marcus A. Wörns; Mf Sprinzl; Andreas Kreft; Tobias Kohl; M Nagel; Jürgen Siebler; Henning Schulze-Bergkamen; You-Wen He; Peter R. Galle; Marcus Schuchmann

BACKGROUND & AIMS Apoptosis is crucially involved in acute and chronic liver injury, including viral, cholestatic, toxic, and metabolic liver disease. Additionally, dysregulation of apoptosis signaling pathways has been implicated in hepatocarcinogenesis. The most prominent members of the apoptosis-mediating tumor necrosis factor receptor superfamily are the TNF-R1 (CD120a) and the CD95 (Apo-1/Fas) receptor. Although extensively studied, the intracellular signaling events in hepatocytes are only incompletely understood. METHODS To examine the role of the caspase-8 homolog cellular FLICE-inhibitory protein (c-FLIP) in liver injury, we generated mice with hepatocyte specific deletion of c-FLIP. Three models of acute liver injury were employed: the agonistic anti-CD95 antibody Jo2, d-galactosamine and LPS (GalN/LPS), and concanavalin A. RESULTS Conditional ablation of c-FLIP in hepatocytes augmented liver injury and cell death in all three models of liver injury. CD95- and GalN/LPS-induced liver injury was ameliorated by a pancaspase inhibitor, while ConA-induced injury was unaffected by caspase inhibition. Augmented activation of the MAPK JNK was observed in parallel to liver injury in c-FLIP knockout mice in all injury models; however, inhibition of JNK only affected TNF- and ConA-mediated injury. CONCLUSIONS In summary, c-FLIP is a central regulator of cell death in hepatocytes, involving increased activation of caspases and the MAPK JNK.


BMC Cancer | 2012

Downregulation of organic cation transporters OCT1 (SLC22A1) and OCT3 (SLC22A3) in human hepatocellular carcinoma and their prognostic significance

Michael Heise; Anja Lautem; Johanna Knapstein; Jörn M. Schattenberg; M. Hoppe-Lotichius; Daniel Foltys; Nina Weiler; Anca Zimmermann; Arno Schad; Dirk Gründemann; Gerd Otto; Peter R. Galle; Marcus Schuchmann; Tim Zimmermann

BackgroundOrganic cation transporters (OCT) are responsible for the uptake and intracellular inactivation of a broad spectrum of endogenous substrates and detoxification of xenobiotics and chemotherapeutics. The transporters became pharmaceutically interesting, because OCTs are determinants of the cytotoxicity of platin derivates and the transport activity has been shown to correlate with the sensitivity of tumors towards tyrosine kinase inhibitors. No data exist about the relevance of OCTs in hepatocellular carcinoma (HCC).MethodsOCT1 (SLC22A1) and OCT3 (SLC22A3) mRNA expression was measured in primary human HCC and corresponding non neoplastic tumor surrounding tissue (TST) by real time PCR (n = 53). Protein expression was determined by western blot analysis and immunofluorescence. Data were correlated with the clinicopathological parameters of HCCs.ResultsReal time PCR showed a downregulation of SLC22A1 and SLC22A3 in HCC compared to TST (p ≤ 0.001). A low SLC22A1 expression was associated with a worse patient survival (p < 0.05). Downregulation was significantly associated with advanced HCC stages, indicated by a higher number of T3 tumors (p = 0.025) with a larger tumor diameter (p = 0.035), a worse differentiation (p = 0.001) and higher AFP-levels (p = 0.019). In accordance, SLC22A1 was less frequently downregulated in tumors with lower stages who underwent transarterial chemoembolization (p < 0.001) and liver transplantation (p = 0.001). Tumors with a low SLC22A1 expression (< median) showed a higher SLC22A3 expression compared to HCC with high SLC22A1 expression (p < 0.001). However, there was no significant difference in tumor characteristics according to the level of the SLC22A3 expression.In the western blot analysis we found a different protein expression pattern in tumor samples with a more diffuse staining in the immunofluorescence suggesting that especially OCT1 is not functional in advanced HCC.ConclusionThe downregulation of OCT1 is associated with tumor progression and a worse patient survival.


Transplant International | 2013

Metabolic syndrome and its association with fatty liver disease after orthotopic liver transplantation

Mf Sprinzl; Arndt Weinmann; Nikola Lohse; Hanna Tönissen; S Koch; Jörn M. Schattenberg; M. Hoppe-Lotichius; Tim Zimmermann; Peter R. Galle; Torsten Hansen; Gerd Otto; Marcus Schuchmann

The metabolic syndrome (MetS) might contribute to morbidity after orthotopic liver transplantation (OLT). For this reason, we searched for MetS‐associated risk factors and analyzed the link with nonalcoholic fatty liver disease (NAFLD) in OLT recipients. De novo MetS affected 32.9% of our cohort (n = 170) within 2 years after OLT. Multivariate analysis identified glycosylated hemoglobin (HbA1c) levels ≥5% [odds ratio (OR) = 3.5; 95% confidence interval (CI) = 1.56–8.13, P = 0.003], diabetes mellitus (OR = 4.31, CI = 1.69–10.99, P = 0.002), and arterial hypertension (OR = 4.59, CI = 1.46–14.49, P = 0.009) as independent risk factors for de novo MetS. MetS incidence correlated with steroid dosage after OLT (5.2 ± 2.4 mg/day vs. 7.1 ± 4.7 mg/day, P = 0.014), and was linked to NAFLD (P = 0.001) via obesity (OR = 4.67, CI = 1.55–14.1, P = 0.006) and dyslipidemia (OR = 4.23, CI = 1.35–13.3, P = 0.013) post‐OLT. In conclusion, we were able to identify low threshold HbA1c as a novel risk factor for MetS after OLT and described a link of MetS with NAFLD in transplant organs. This study also indicated that steroid treatment is associated with MetS rates after OLT.


Hormone Research in Paediatrics | 2010

Alterations in Lipid and Carbohydrate Metabolism in Patients with Classic Congenital Adrenal Hyperplasia due to 21-Hydroxylase Deficiency

Anca Zimmermann; Paula Grigorescu-Sido; Camelia Al-Khzouz; Karen Patberg; Simona Bucerzan; Egbert Schulze; Tim Zimmermann; Heidi Rossmann; Hans-Christian Geiss; Karl J. Lackner; Matthias M. Weber

Background: Classic 21-hydroxylase deficiency (21HD) presents some traits of the metabolic syndrome. Aim: To characterize discrete alterations of lipid and carbohydrate metabolism in children and young adults with classic 21HD, which could predict early atherogenesis. Patients and Methods: Twenty-seven Caucasian patients with classic 21HD (4–31 years); 27 sex-, age- and BMI-matched controls. Clinical parameters, hormonal status and genotype were assessed in all patients. Lipid parameters, including relative (%) and absolute (mg/dl) small-dense low-density lipoproteins subfractions (sd-LDL) were measured in patients and controls. Oral glucose tolerance tests were performed in both groups. Results: sd-LDL (%) was significantly higher in patients than controls (39.7 ± 5.9 vs. 35.5 ± 5.7%; p = 0.008). The same applies for absolute sd-LDL (mg/dl) (42.6 ± 11.9 vs. 36.4 ± 7.5; p = 0.029). HDL-cholesterol was lower in patients (p = 0.032). Fasting glucose and insulin were significantly higher in patients. Similar differences were noticed for HOMA-IR (p = 0.001), IRI (p = 0.001) and HOMA-B (p = 0.002). IRI correlated directly and significantly with the total hydrocortisone dose and the duration of treatment. Fasting glucose correlated with absolute sd-LDL. No obvious differences were seen between clinical forms or genotype groups. Conclusions: Substitution therapy should be adapted particularly at young ages to prevent early atherogenesis and cardiovascular risk in later life.


European Journal of Internal Medicine | 2010

Liver transplanted patients with preoperative autoimmune hepatitis and immunological disorders are at increased risk for Post-Transplant Lymphoproliferative Disease (PTLD).

Tim Zimmermann; M. Hoppe-Lotichius; Vuk Tripkovic; Ana Paula Barreiros; Thomas C. Wehler; Anca Zimmermann; Jörn M. Schattenberg; Michael Heise; Stefan Biesterfeld; Peter R. Galle; Gerd Otto; Marcus Schuchmann

BACKGROUND Long term immunosuppression and therapy of acute rejections result in a 20-120-fold increased risk to develop Non Hodgkin lymphoma (NHL). Since immunosuppressive therapy and immunological disorders are major risk factors for the development of NHL in the non-transplant population we aimed to analyze risk factors for PTLD in our cohort of liver transplanted (LT) patients. METHODS We analyzed retrospectively 431 patients liver transplanted between 1998 and 2008. RESULTS PTLD was diagnosed in eleven of 431 patients (2.6%). PTLD, especially late PTLD, was significantly more frequent in patients who received steroids before LT (Kaplan-Meier: p<0.001). Moreover PTLD in immunocompromised patients with preoperative steroid treatment occurred at a significantly younger age (49.5+/-4.7 years) compared to patients without steroids (60.6+/-5.1 years; p=0.006). Multivariate analysis revealed pretransplant steroid treatment and liver transplantation for autoimmune hepatitis as main risk factors for the development of PTLD after liver transplantation (p<0.001). CONCLUSION Liver transplanted patients who received steroids before LT due to immunological disorders and patients with autoimmune hepatitis seem to be at particular high risk to develop PTLD. Prospective cohort studies including immunoepidemiologic investigations of abnormalities of cellular, humoral and innate immunity should be carried out to identify predictive factors and patients at risk.


European Journal of Internal Medicine | 2011

Alterations in lipid, carbohydrate and iron metabolism in patients with non-alcoholic steatohepatitis (NASH) and metabolic syndrome

Anca Zimmermann; Tim Zimmermann; Jörn M. Schattenberg; Sebastian Pöttgen; Johannes Lotz; Heidi Rossmann; Ralf Roeddiger; Stefan Biesterfeld; Hans-Christian Geiss; Marcus Schuchmann; Peter R. Galle; Matthias M. Weber

BACKGROUND NASH (non-alcoholic steatohepatitis) is considered the hepatic manifestation of the metabolic syndrome (MS). We aimed to analyze lipid, carbohydrate, and iron metabolism in NASH. PATIENTS, METHODS 37 patients with MS (17 M/20 F, 51+/-15 years), elevated transaminases; 25 patients had histologically proven NASH (NAS score≥5), 12 patients had toxic background (nonNASH). 37 age, sex, BMI-matched healthy controls. Lipid variables, LDL-subfractions, iron, ferritin, transferrin (T), transferrin saturation (TS), and hepcidin (H) were measured in patients/controls. Oral glucose tolerance tests were performed. RESULTS NASH patients with steatosis gr. 2 and 3 (>33% hepatic fat) had higher sd-LDL (mg/dl) concentrations than patients with steatosis gr. 1 (<33%) (p=0.002), nonNASH patients (p=0.03) and controls (p=0.001). Sd absolute (mg/dl) correlated directly with the steatosis grade only in patients with NASH and steatosis >33% (p=0.04). NASH-patients showed higher insulin, C-peptide and IRI values than nonNASH patients (p=0.034; 0.032; 0.04). H was increased in patients versus controls (p<0.001). H correlated with ferritin in MS-patients (p=0.01), correlated directly with sd-LDL (mg/dl) (p=0.017) and IRI (p<0.001) and indirectly with HDL (p=0.05) in NASH. No associations between hepatic inflammation/iron content on liver biopsy and variables of lipid metabolism were found but hepcidin correlated with hepatic inflammation in all patients and with NAS scores in NASH. CONCLUSIONS NASH-patients show insulin resistance and increased sd-LDL subfractions, suggesting an atherogenic profile. The correlation of H with sd-LDL and IRI, without relation to hepatic iron content suggests a putative link between inflammation, carbohydrate and lipid metabolism in NASH.


American Journal of Physiology-gastrointestinal and Liver Physiology | 2012

Increased hepatic fibrosis and JNK2-dependent liver injury in mice exhibiting hepatocyte-specific deletion of cFLIP

Jörn M. Schattenberg; M Nagel; Y.O. Kim; Tobias Kohl; Marcus A. Wörns; Tim Zimmermann; Arno Schad; Thomas Longerich; Detlef Schuppan; You-Wen He; Peter R. Galle; Marcus Schuchmann

Chronic liver disease promotes hepatocellular injury involving apoptosis and triggers compensatory regeneration that leads to the activation of quiescent stellate cells in the liver. The deposition of extracellular matrix from activated myofibroblasts promotes hepatic fibrosis and the progression to cirrhosis with deleterious effects on liver physiology. The role of apoptosis signaling pathways in the development of fibrosis remains undefined. The aim of the current study was to determine the involvement of the caspase-8 homologue cellular FLICE-inhibitory protein (cFLIP) during the initiation and progression of fibrosis. Liver injury and fibrosis from carbon tetrachloride (CCl(4)) and thioacetamide (TAA) were examined in mice exhibiting a hepatocyte-specific deletion of cFLIP (flip(-/-)). Acute liver injury from CCl(4) and TAA were enhanced in flip(-/-) mice. This was accompanied by increased activation of caspase-3 and -9, pronounced phosphorylation of JNK, and decreased phosphorylation of Erk. Deletion of the cJun NH(2)-terminal kinase 2 (JNK2) in flip(-/-) mice protected from injury. Hepatic fibrosis was increased at baseline in 12-wk-old flip(-/-) mice, and progression of fibrosis from TAA was accelerated compared with the wild type. In conclusion, deletion of cFLIP in hepatocytes leads to increased fibrosis and accelerated fibrosis progression. This is accompanied by increased injury involving the activation of caspases and JNK2. Thus predisposition to liver injury involving increased hepatocellular apoptosis is a critical mediator of accelerated fibrogenesis, and prevention of liver injury will be a most important measure for patients with chronic liver disease.


International Journal of Colorectal Disease | 2010

Low expression of chemokine receptor CCR5 in human colorectal cancer correlates with lymphatic dissemination and reduced CD8+ T-cell infiltration

Tim Zimmermann; Markus Moehler; Ines Gockel; George Sgourakis; Stefan Biesterfeld; Michaela Müller; Martin R. Berger; Hauke Lang; Peter R. Galle; Carl C. Schimanski

BackgroundChemokines and their receptors have been proposed to distinctly contribute to tumor growth, dissemination, and local immune escape. The aim of this study was to evaluate the relevance of the chemokine receptor CCR5 expression for the progression of human colorectal cancer.MethodsCCR5 expression was assessed by RT-PCR analysis in 103 colorectal cancer patients. Intensity of CCR5 expression was correlated with both tumor and patient characteristics. Infiltration of tumor margins with CD8+ T cells in the context of CCR5 expression was analyzed by immunohistochemistry in additional 18 colorectal cancer specimens.ResultsHuman colorectal cancer revealed variable intensities of CCR5 expression ranging from absent (48/103: 47%), weak (30/103: 29%), intermediate (13/103: 13%), to strong (12/103: 12%). Absent or weak CCR5 expression was significantly associated with advanced UICC stages (P = 0.02) and lymphatic metastasis (P = 0.05). In addition, CCR5 expression positively correlated with CD8+ T-cell infiltration in tumor margins (P = 0.001).ConclusionIn summary, intermediate and strong CCR5 expression was significantly associated with nonmetastatic colorectal cancer and increased CD8+ T-cell infiltration.

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