Biology subjects

Janssen, K.-P.

Publications and source records attributed to Janssen, K.-P..

8 recordsLinked to original sources

bioRxiv2025

A microbial metabolite protects against graft-versus-host disease via mTORC1 and STING-dependent intestinal regeneration

Changes in the intestinal microbiome and microbiota-derived metabolites predict clinical outcomes after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Here, we report that desaminotyrosine (DAT), a product of bacterial flavonoid metabolism, correlates with improved overall survival and reduced relapse rates in allo-HSCT patients. In preclinical mouse models, treatment with synthetic DAT prevents graft-versus-host disease by protecting the intestinal barrier and promoting intestinal regeneration and contributes to graft-vs.-leukemia responses. DATs beneficial effects on intestinal regeneration remain effective despite broad-spectrum antibiotics-induced dysbiosis, also when administered by fecal microbiota transfer with flavonoid-degrading F. plautii. Mechanistically, DAT promotes mTORC1-dependent activation and proliferation of intestinal stem cells, with concomitant engagement of the innate immune receptor STING required to mitigate metabolic stress and maintain an undifferentiated stem cell state independently of type-I interferon responses. Additionally, DAT can skew T cells towards an effector phenotype to modulate graft-versus-leukemia responses. Our data uncover DATs dual, tissue- and immune-modulating properties and underscore its potential in precision microbiome-based therapies to improve tissue regeneration and minimize immune-mediated side effects.

immunology↗

bioRxiv2024

Endoplasmic reticulum stress signaling actively contributes to therapy resistance in colorectal cancer

PurposeWe investigated the involvement of endoplasmic reticulum (ER) stress signaling in cancer cell responses to chemo- and radiotherapy, focusing on three main ER stress mediators, the transcription factors ATF4, XBP1 and ATF6. MethodsPublic cancer genome datasets were assessed for alterations in ER stress mediators. Surgically resected colorectal cancer tissues were tested by flow cytometry and used to generate patient-derived organoids. Human cell lines and organoids were characterized under oxaliplatin treatment, alone or combined with pharmacological inhibitors of the three ER stress branches, or X-ray irradiation, for cytotoxicity, activation of ER stress and proteome changes. To monitor ER stress in real time, stable HEK293 kidney epithelial cell lines were established expressing ATF4, XBP1, or ATF6, fused with a fluorophore. ResultsGenomic amplification of ATF6, but not ATF4 or XBP1, was frequent in solid tumor entities like breast, lung and colorectal cancer and significantly associated with reduced disease-free survival. In colorectal cancer, increased ATF6 was associated with genetic instability. Basal ER stress mediator expression was correlated to chemoresistance in colorectal cancer cell lines, and generally high in cancer cells compared to HEK293 cells. With proteomics and live HEK293-based reporter lines, we noted that oxaliplatin treatment induced ER stress in a remarkably different way from the canonical ER stress inducer thapsigargin. Moreover, modulation of ER stress signaling by exogenous expression of the stress mediators positively affects chemoresistance, and pharmacological inhibition of ATF6 sensitizes ER-stressed HCT116 colorectal cancer cells to chemotherapy. Of note, cellular stress responses was strongly dependent on the individual transcription factor: XBP1-driven response appeared multi-functional, involved in ribosome biogenesis stress and associated with oxaliplatin resistance. ATF6-dependent stress signaling was involved in DNA damage repair, and was essential for radioresistance. Moreover, chemoresistance in HCT116 cancer cells was impaired by pharmacological ATF6 inhibition. ConclusionActivation of the ER stress signaling may be critically involved in acquired chemo- and radioresistance. Due to their apparent cytoprotective roles, ATF6 and XBP1 could be attractive predictive biomarkers and putative therapeutic targets. SUMMARYTo address their roles in the clinical context, genomic alterations of ATF4, XBP1 and/or ATF6 in human solid tumors were assessed with respect to prognosis and genomic instability. Moreover, surgically resected CRC patient tissues were tested for expression of ER stress markers by flow cytometry and associated with clinical characteristics. In addition, a panel of human cell lines and patient-derived colon organoids were characterized under therapeutic conditions for expression and activation of ER stress proteins, and resulting cytotoxicity was determined. To monitor and modulate ER stress activation in live cells with subcellular resolution, stable reporter cell lines expressing ATF4, sXBP1 or ATF6 proteins fused with a fluorophore were established. These lines were tested for gene or protein expression and cytotoxicity assays to analyze how activation or inhibition of ER stress proteins affects the cellular responses to oxaliplatin treatment or X-ray irradiation. Finally, mass spectrometric proteome analysis was performed to obtain an unbiased readout on the cellular responses to chemotherapy driven by the activation of the ER stress proteins.

cancer biology↗

bioRxiv2023

ATF6 activation alters colonic lipid metabolism causing tumor-associated microbial adaptation

Endoplasmic reticulum unfolded protein responses (UPRER) contribute to cancer development and the activating transcription factor 6 (ATF6) is involved in microbiota-dependent tumorigenesis. Here, we substantiate the clinical relevance of ATF6 in early-onset and late colorectal cancer patient cohorts. Transcriptional analysis in intestinal epithelial cells (IEC) of ATF6 transgenic mice (nATF6IEC) identified bacteria-specific changes in cellular metabolism enriched for fatty acid biosynthesis. Untargeted metabolomics and isotype-labeling confirmed ATF6-related enrichment of long chain fatty acids in colonic tissue of patients, mice and organoid cultures. FASN inhibition and microbiota transfer in germ-free nATF6IEC mice confirmed the causal involvement of ATF6-induced lipid alterations in tumorigenesis. The selective expansion of tumor-relevant microbial taxa was mechanistically linked to long chain fatty acid exposure, using bioorthogonal non-canonical amino acid tagging (BONCAT) and growth analysis of Desulfovibrio isolates. We postulate chronic ATF6 signaling in the epithelium to select for tumor-promoting microbiota by altering lipid metabolism. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=126 SRC="FIGDIR/small/565267v2_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@be3756org.highwire.dtl.DTLVardef@231da4org.highwire.dtl.DTLVardef@16f3aaeorg.highwire.dtl.DTLVardef@1758fe3_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical Abstract:C_FLOATNO Chronic ATF6 signaling in the colonic epithelium alters lipid metabolism to select a tumor-promoting microbiota C_FIG O_LIBiallelic expression of activated ATF6 (p50 nuclear fragment) in intestinal epithelial cells (nATF6IEC) induces spontaneous colon tumors in SPF but not GF mice C_LIO_LIMechanistically, biallelic SPF nATF6IEC mice alter colonic lipid metabolism, including the upregulation of LCFAs and Fasn C_LIO_LIInhibition of FASN prevents colon tumor formation in mice, and reduces the tumor-promoting potential of the intestinal microbiota (FMT) C_LIO_LIExposure of fl/fl control mouse microbiota to LCFAs ex vivo translationally activates tumor-associated bacteria, including Desulfovibrio fairfieldensis C_LIO_LIHuman CRC patients show ATF6 upregulation, FASN co-occurrence and increased LCFAs in T tissue C_LIO_LIATF6 activity links with CRC-associated microbiota in patients, including Desulfovibrio C_LI Created with BioRender.com nATF6: activated activating transcription factor 6; LCFA: long-chain fatty acids; SAFA: saturated fatty acids; Fasn: fatty acid synthase; C75 i.p.: intraperitoneal injection of the Fasn inhibitor C75.

cancer biology↗

bioRxiv2022

Gut microbial disruption in critically ill patients with COVID-19 associated pulmonary aspergillosis

ObjectivesCOVID-19 disease can be exacerbated by Aspergillus superinfection (CAPA). The causes of CAPA are not yet fully understood. Recently, alterations in the gut microbiome have been associated with a complicating course and increasing severity of COVID-19 disease, most likely via immunological mechanisms. Aim of this study was to investigate a potential association between severe CAPA and alterations in the gut and bronchial microbiota. MethodsWe performed 16S rRNA gene amplicon sequencing of stool and bronchial samples from a total of 16 COVID-19 patients with CAPA and 26 patients without CAPA. All patients were admitted to the intensive care unit. Results were carefully tested for potential influences on the microbiome during hospitalization. ResultsWe found that late in COVID-19 disease, CAPA patients exhibited a trend towards reduced gut microbial diversity. Furthermore, late stage CAPA disease showed an increased presence of Staphylococcus epidermidis in the gut. This is not found in late non-CAPA cases or early disease. The analysis of bronchial samples did not show significant results. ConclusionsThis is the first study showing alterations in the gut microbiome accompany severe CAPA and possibly influence the hosts immunological response. In particular, an increase of Staphylococcus epidermidis in the intestine could be of importance. SummaryThe composition of intestinal bacteria in severe CAPA disease is altered with an increase in Staphylococcus epidermidis in the gut. Alterations in the composition of intestinal bacteria in severe CAPA may indicate immunologic involvement of the gut in the disease.

microbiology↗

bioRxiv2022

B/T cell crosstalk and aberrant inflammatory IgG exacerbate autoimmune intestinal inflammation

Dysregulated B cell responses have been described in inflammatory-bowel disease (IBD) patients; however, the role of B cells in IBD pathology remained incompletely understood. We here described Wiskott-Aldrich Syndrome interacting protein deficient (Wipf1-/-) mice as novel mouse model of spontaneous, chronic colitis modelling human IBD. Concomitant with aberrant IgG production in colonic tissue of Wipf1-/- mice, we identified systemic, hypo-sialylated IgG as drivers of IL-1{beta} production in monocytes. Pathological antibody production was promoted by the hyper-reactivity of Wipf1-/- B cells in response to LPS stimulation, resulting in efficient activation of the MAPK/Erk and mTOR/Akt/4E-BP1 pathways and heightened metabolic activity. In addition to abundant inflammatory IgG, we found that B cells directly promoted the production of pro-inflammatory cytokines by intestinal CD4+ T cells. B/T co-culture assays defined the co-stimulatory molecule CD86 as driver of IFN-{gamma} and GM-CSF production by CD4+ T cells. CD86 expression was further enhanced by the presence of sCD40L, which was elevated in sera of Wipf1-/- mice. Similarly, colonic B cells of IBD patients expressed increased mRNA levels of CD86 correlating with enhanced levels of systemic sCD40L. Together, B cell-mediated pro-inflammatory cytokine secretion and B cell-derived inflammatory antibody production contributed to exacerbated pathogenesis during intestinal inflammation. O_FIG O_LINKSMALLFIG WIDTH=168 HEIGHT=200 SRC="FIGDIR/small/507066v1_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@1449ae8org.highwire.dtl.DTLVardef@116045borg.highwire.dtl.DTLVardef@77f3f2org.highwire.dtl.DTLVardef@130a271_HPS_FORMAT_FIGEXP M_FIG C_FIG One Sentence SummaryB cells fuel intestinal inflammation

immunology↗

bioRxiv2022

The gut microbiota promotes liver regeneration through hepatic membrane phospholipid synthesis

Background & AimsHepatocyte growth and proliferation is dependent on the synthesis of membrane phospholipids. Lipid synthesis, in turn, requires short chain fatty acids (SCFA) generated by bacterial fermentation, delivered through the gut- liver axis. We therefore hypothesized that dysbiotic insults like antibiotics treatment not only negatively affect gut microbiota, but also impair hepatic lipid synthesis and liver regeneration. MethodsStable isotope labelling and 70% partial hepatectomy (PHx) was carried out in C57Bl/6J wildtype mice, in mice treated with broad-spectrum antibiotics, in germfree mice and gnotobiotic mice colonized with minimal microbiota. Microbiome was analysed by 16S rRNA gene sequencing and microbial culture. Gut content, liver and blood were tested by lipidomics mass spectrometry, qRT-PCR, immunoblot and immunohistochemistry for expression of proliferative and lipogenic markers. Matched biopsies from hyperplastic and hypoplastic liver tissue of human patients subjected to portal vein embolization were analysed by qRT-PCR for lipogenic enzymes and results were correlated with liver volumetry. ResultsThree days of antibiotics treatment induced persistent dysbiosis with significantly decreased beta-diversity and richness, but massive increase of Proteobacteria, accompanied by decreased colonic SCFA. After PHx, antibiotics- treated mice showed delayed liver regeneration, increased mortality, impaired hepatocyte proliferation and decreased hepatic phospholipid synthesis. Expression of the key lipogenic enzyme SCD1 was upregulated after PHx, but delayed by antibiotics-treatment. Germfree mice essentially recapitulated the phenotype of antibiotics-treatment. Importantly, phospholipid synthesis, hepatocyte proliferation, liver regeneration and survival were rescued in gnotobiotic mice colonized with a minimal SCFA-producing microbial community. SCD1 was required for human hepatoma cell proliferation, and its hepatic expression was associated with liver regeneration and hyperproliferation in human patients. ConclusionGut microbiota are pivotal for hepatic membrane phospholipid synthesis and liver regeneration. Lay SummaryGut microbiota affects the liver lipid metabolism through the gut-liver axis, and microbial metabolites promote liver regeneration. Perturbations of the microbiome, e.g., by antibiotics treatment, impair the production of bacterial metabolites, which serve as building blocks for new membrane lipids in liver cells. As a consequence, hepatocyte growth and proliferation, and ultimately, liver regeneration and survival after liver surgery is impaired. HighlightsO_LIPartial hepatectomy in mice pretreated with antibiotics is associated with impaired hepatocyte proliferation and phospholipid synthesis, delayed liver regeneration and increased mortality C_LIO_LIThe delay in liver regeneration and impaired lipogenesis upon antibiotics treatment is preceded by dysbiosis of gut microbiota, increase of Proteobacteria and decreased short-chain fatty acids in the gut C_LIO_LIPartial hepatectomy in germfree mice essentially phenocopies the detrimental effects of antibiotic treatment C_LIO_LILiver regeneration and mortality, as well as phospholipid synthesis and hepatocyte proliferation in germfree mice are fully rescued upon colonisation with a minimal gut bacterial consortium capable of short-chain fatty acid production C_LIO_LIIn human patients, the intrahepatic expression of lipid synthesis enzymes positively correlates with proliferation and liver regeneration in the clinic C_LIO_LIThus, liver regeneration is affected by composition of gut microbiota C_LIO_LIClinically, pre-operative analysis of the gut microbiome may serve as biomarker to determine the extent of liver resections C_LI

cell biology↗

bioRxiv2021

Gut Bacterial Dysbiosis and Instability is Associated with the Onset of Complications and Mortality in COVID-19

ObjectiveThere is a growing debate about the involvement of the gut microbiome in COVID-19, although it is not conclusively understood whether the microbiome has an impact on COVID-19, or vice versa, especially as analysis of amplicon data in hospitalized patients requires sophisticated cohort recruitment and integration of clinical parameters. Here, we analyzed fecal and saliva samples from SARS-CoV-2 infected and post COVID-19 patients and controls considering multiple influencing factors during hospitalization. Design16S rRNA gene sequencing was performed on fecal and saliva samples from 108 COVID-19 and 22 post COVID-19 patients, 20 pneumonia controls and 26 asymptomatic controls. Patients were recruited over the first and second corona wave in Germany and detailed clinical parameters were considered. Serial samples per individual allowed intra-individual analysis. ResultsWe found the gut and oral microbiota to be altered depending on number and type of COVID-19-associated complications and disease severity. The occurrence of individual complications was correlated with low-risk (e.g., Faecalibacterium prausznitzii) and high-risk bacteria (e.g., Parabacteroides). We demonstrated that a stable gut bacterial composition was associated with a favorable disease progression. Based on gut microbial profiles, we identified a model to estimate mortality in COVID-19. ConclusionGut microbiota are associated with the occurrence of complications in COVID-19 and may thereby influencing disease severity. A stable gut microbial composition may contribute to a favorable disease progression and using bacterial signatures to estimate mortality could contribute to diagnostic approaches. Importantly, we highlight challenges in the analysis of microbial data in the context of hospitalization.

microbiology↗

bioRxiv2018

Two Isoforms of the Guanine Nucleotide Exchange Factor, Daple/CCDC88C Cooperate as Tumor Suppressors

Previously Aznar et al., showed that Daple enables Wnt/Frizzled receptors to transactivate trimeric G proteins during non-canonical Wnt signaling via a novel G-protein binding and activating (GBA) motif. By doing so, Daple serves as a double-edged sword; earlier during oncogenesis it suppresses neoplastic transformation and tumor growth, but later it triggers epithelial messenchymal transition (EMT). We have identified and characterized two isoforms of the human Daple/CCDC88c gene. While both isoforms cooperatively suppress tumor growth via their GBA motif, only the full-length transcript triggers EMT and invasion. Aspirin suppresses the full-length transcript and protein but upregulates the short isoform. Both isoforms are suppressed during colon cancer progression, and their reduced expression carries additive prognostic significance. These findings provide insights into the opposing roles of Daple during cancer progression and define the G protein regulatory GBA motif as one of the minimal modules essential for Daples role as a tumor suppressor.

cancer biology↗