Simon Sirtl

Dr. Simon Sirtl

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Research Focus & Metrics

Academic Career Length

6Years (2021-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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21 December 2023 in Gut
Verified
Journal Article
Open access
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CAChristoph Ammer-Herrmenau
Christoph Ammer-Herrmenau
KAKai L Antweiler
Kai L Antweiler
TAThomas Asendorf
Thomas Asendorf
GBGeorg Beyer
Georg Beyer
SBSoeren M Buchholz
Soeren M Buchholz
Albrecht NeesseAlbrecht Neesse
Albrecht Neesse
Objective Early disease prediction is challenging in acute pancreatitis (AP). Here, we prospectively investigate whether the microbiome predicts severity of AP (Pancreatitis—Microbiome As Predictor of Severity; P-MAPS) early at hospital admission. Design Buccal and rectal microbial swabs were collected from 424 patients with AP within 72 hours of hospital admission in 15 European centres. All samples were sequenced by full-length 16S rRNA and metagenomic sequencing using Oxford Nanopore Technologies. Primary endpoint was the association of the orointestinal microbiome with the revised Atlanta classification (RAC). Secondary endpoints were mortality, length of hospital stay and severity (organ failure >48 hours and/or occurrence of pancreatic collections requiring intervention) as post hoc analysis. Multivariate analysis was conducted from normalised microbial and corresponding clinical data to build classifiers for predicting severity. For functional profiling, gene set enrichment analysis (GSEA) was performed and normalised enrichment scores calculated. Results After data processing, 411 buccal and 391 rectal samples were analysed. The intestinal microbiome significantly differed for the RAC (Bray-Curtis, p value=0.009), mortality (Bray-Curtis, p value 0.006), length of hospital stay (Bray-Curtis, p=0.009) and severity (Bray-Curtis, p value=0.008). A classifier for severity with 16 different species and systemic inflammatory response syndrome achieved an area under the receiving operating characteristic (AUROC) of 85%, a positive predictive value of 67% and a negative predictive value of 94% outperforming established severity scores. GSEA revealed functional pathway units suggesting elevated short-chain fatty acid (SCFA) production in severe AP. Conclusions The orointestinal microbiome predicts clinical hallmark features of AP, and SCFAs may be used for future diagnostic and therapeutic concepts. Trial registration number NCT04777812.

18 April 2023 in Gut
Verified
Journal Article
Open access
PDF file
MŻMichal Żorniak
Michal Żorniak
SSSimon Sirtl
Simon Sirtl
GBGeorg Beyer
Georg Beyer
UMUjjwal Mukund Mahajan
Ujjwal Mukund Mahajan
KBKatharina Bretthauer
Katharina Bretthauer
JMJulia Mayerle
Julia Mayerle
Objective In up to 20% of patients, the aetiology of acute pancreatitis (AP) remains elusive and is thus called idiopathic. On more detailed review these cases can often be explained through biliary disease and are amenable to treatment. Findings range from biliary sludge to microlithiasis but their definitions remain fluid and controversial. Design A systematic literature review (1682 reports, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines) analysed definitions of biliary sludge and microlithiasis, followed by an online international expert survey (30 endoscopic ultrasound/hepatobiliary and pancreatic . Results In 13% of original articles and 19.2% of reviews, microlithiasis and biliary sludge were used synonymously. In the survey, 41.7% of experts described the term ‘sludge’ and ‘microlithiasis’ as identical findings. As a consequence, three definitions were proposed, agreed on and confirmed by voting to distinctly discriminate between biliary sludge (hyperechoic material without acoustic shadowing) and microlithiasis (echorich calculi of ≤5 mm with acoustic shadowing) as opposed to larger biliary stones, both for location in gallbladder and bile ducts. In an initial attempt to investigate the clinical relevance in a retrospective analysis in 177 confirmed cases in our hospital, there was no difference in severity of AP if caused by sludge, microlithiasis or stones. Conclusion We propose a consensus definition for the localisation, ultrasound morphology and diameter of biliary sludge and microlithiasis as distinct entities. Interestingly, severity of biliary AP was not dependent on the size of concrements warranting prospective randomised studies which treatment options are adequate to prevent recurrence.

15 January 2021 in Diagnostics
Verified
Journal Article
Open access
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SSSimon Sirtl
Simon Sirtl
ATAndrei Todica
Andrei Todica
HIHarun Ilhan
Harun Ilhan
MZMichal Zorniak
Michal Zorniak
PBPeter Bartenstein
Peter Bartenstein
JMJulia Mayerle
Julia Mayerle
An 82-year-old man suffering from prostate cancer that was scheduled for a radioreceptor-ligand therapy (RLT) presented with jaundice to our service. An abdominal ultrasound (US) revealed obstructive extrahepatic cholestasis due to a solid lesion located in the uncinate process of the pancreas. The Prostate Specific Membrane Antigen (PSMA) PET/CT prior to RLT showed multilocular PSMA positive tumor lesions in the lymph nodes, the lung and the pancreas. On request of the cancer board, an Endoscopic Ultrasound (EUS)-guided Fine-Needle Aspiration (FNA) of the pancreatic mass was performed revealing invasive pancreatic ductal adenocarcinoma incompatible with a prostate cancer metastasis leading to the diagnosis of a PSMA positive pancreatic ductal adenocarcinoma.

21 September 2023 in World Journal of Gastroenterology
Verified
Journal Article
Open access
SSSimon Sirtl
Simon Sirtl
MŻMichał Żorniak
Michał Żorniak
EHEric Hohmann
Eric Hohmann
GBGeorg Beyer
Georg Beyer
MDMiriam Dibos
Miriam Dibos
UMUjjwal Mukund Mahajan
Ujjwal Mukund Mahajan
Pancreatic ductal adenocarcinoma (PDAC) remains a significant public health challenge and is currently the fourth leading cause of cancer-related mortality in developed countries. Despite advances in cancer treatment, the 5-year survival rate for patients with PDAC remains less than 5%. In recent years, neoadjuvant therapy (NAT) has emerged as a promising treatment option for many cancer types, including locally advanced PDAC, with the potential to improve patient outcomes. To analyze the role of NAT in the setting of locally advanced PDAC over the past decade, a systematic literature search was conducted using PubMed and Web of Science. The results suggest that NAT may reduce the local mass size, promote tumor downstaging, and increase the likelihood of resection. These findings are supported by the latest evidence-based medical literature and the clinical experience of our center. Despite the potential benefits of NAT, there are still challenges that need to be addressed. One such challenge is the lack of consensus on the optimal timing and duration of NAT. Improved criteria for patient selection are needed to further identify PDAC patients likely to respond to NAT. In conclusion, NAT has emerged as a promising treatment option for locally advanced PDAC. However, further research is needed to optimize its use and to better understand the role of NAT in the management of this challenging disease. With continued advances in cancer treatment, there is hope of improving the outcomes of patients with PDAC in the future.

26 October 2022 in Cancers
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Journal Article
Open access
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NKNajib Ben Khaled
Najib Ben Khaled
KHKatharina Hammer
Katharina Hammer
LYLiangtao Ye
Liangtao Ye
AAAhmed Alnatsha
Ahmed Alnatsha
SWSebastian A Widholz
Sebastian A Widholz
ETEnrico N De Toni
Enrico N De Toni
Chemotherapy, the standard treatment for pancreatic ductal adenocarcinoma (PDAC), has only a modest effect on the outcome of patients with late-stage disease. Investigations of the genetic features of PDAC have demonstrated a frequent occurrence of mutations in genes involved in homologous recombination (HR), especially in the breast cancer susceptibility gene 2 (BRCA2). Olaparib, a poly(ADP-ribose) polymerase (PARP) inhibitor, is approved as a maintenance treatment for patients with advanced PDAC with germline BRCA1/2 mutations following a platinum-containing first-line regimen. Limitations to the use of PARP inhibitors are represented by the relatively small proportion of patients with mutations in BRCA1/2 genes and the modest capability of these substances of inducing objective response. We have previously shown that pancreatic cancer with BRCA2 mutations exhibits a remarkably enhanced sensitivity towards tumor-necrosis-factor-related apoptosis-inducing ligand (TRAIL) receptor-stimulating agents. We thus aimed to investigate the effect of combined treatment with PARP inhibitors and TRAIL receptor-stimulating agents in pancreatic cancer and its dependency on the BRCA2 gene status. The respective effects of TRAIL-targeting agents and the PARP inhibitor olaparib or of their combination were assessed in pancreatic cancer cell lines and patient-derived organoids. In addition, BRCA2-knockout and -complementation models were investigated. The effects of these agents on apoptosis, DNA damage, cell cycle, and receptor surface expression were assessed by immunofluorescence, Western blot, and flow cytometry. PARP inhibition and TRAIL synergized to cause cell death in pancreatic cancer cell lines and PDAC organoids. This effect proved independent of BRCA2 gene status in three independent models. Olaparib and TRAIL in combination caused a detectable increase in DNA damage and a concentration-dependent cell cycle arrest in the G2/M and S cell cycle phases. Olaparib also significantly increased the proportion of membrane-bound death receptor 5. Our results provide a preclinical rationale for the combination of PARP inhibitors and TRAIL receptor agonists for the treatment of pancreatic cancer and suggest that the use of PARP inhibitors could be extended to patients without BRCA2 mutations if used in combination with TRAIL agonists.

31 July 2021 in BMC Gastroenterology
Verified
Journal Article
Open access
PDF file
CAChristoph Ammer-Herrmenau
Christoph Ammer-Herrmenau
TAThomas Asendorf
Thomas Asendorf
GBG. Beyer
G. Beyer
SBS. M. Buchholz
S. M. Buchholz
SCS. Cameron
S. Cameron
Albrecht NeesseAlbrecht Neesse
Albrecht Neesse
Background: Acute pancreatitis (AP) is an inflammatory disorder that causes a considerable economic health burden. While the overall mortality is low, around 20% of patients have a complicated course of disease resulting in increased morbidity and mortality. There is an emerging body of evidence that the microbiome exerts a crucial impact on the pathophysiology and course of AP. For several decades multiple clinical and laboratory parameters have been evaluated, and complex scoring systems were developed to predict the clinical course of AP upon admission. However, the majority of scoring systems are determined after several days and achieve a sensitivity around 70% for early prediction of severe AP. Thus, continued efforts are required to investigate reliable biomarkers for the early prediction of severity in order to guide early clinical management of AP patients. Methods: We designed a multi-center, prospective clinical-translational study to test whether the orointestinal microbiome may serve as novel early predictor of the course, severity and outcome of patients with AP. We will recruit 400 AP patients and obtain buccal and rectal swabs within 72 h of admission to the hospital. Following DNA extraction, microbiome analysis will be performed using 3rd generation sequencing Oxford Nanopore Technologies (ONT) for 16S rRNA and metagenomic sequencing. Alpha- and beta-diversity will be determined and correlated to the revised Atlanta classification and additional clinical outcome parameters such as the length of hospital stay, number and type of complications, number of interventions and 30-day mortality. Discussion: If AP patients show a distinct orointestinal microbiome dependent on the severity and course of the disease, microbiome sequencing could rapidly be implemented in the early clinical management of AP patients in the future. Trial registration: ClinicalTrials.gov Identifier: NCT04777812