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ObjectiveHelicobacter pyloriinfection is the most prevalent bacterial infection worldwide. Besides being the most important risk factor for gastric cancer development, epidemiological data show that infected individuals harbour a nearly twofold increased risk to develop colorectal cancer (CRC). However, a direct causal and functional connection between H. pyloriinfection and colon cancer is lacking.DesignWe infected two Apc-mutant mouse models and C57BL/6 mice with H. pyloriand conducted a comprehensive analysis of H. pylori-induced changes in intestinal immune responses and epithelial signatures via flow cytometry, chip cytometry, immunohistochemistry and single cell RNA sequencing. Microbial signatures were characterised and evaluated in germ-free mice and via stool transfer experiments.ResultsH. pyloriinfection accelerated tumour development in Apc-mutant mice. We identified a unique H. pylori-driven immune alteration signature characterised by a reduction in regulatory T cells and pro-inflammatory T cells. Furthermore, in the intestinal and colonic epithelium, H. pyloriinduced pro-carcinogenic STAT3 signalling and a loss of goblet cells, changes that have been shown to contribute—in combination with pro-inflammatory and mucus degrading microbial signatures—to tumour development. Similar immune and epithelial alterations were found in human colon biopsies from H. pylori-infected patients. Housing of Apc-mutant mice under germ-free conditions ameliorated, and early antibiotic eradication of H. pyloriinfection normalised the tumour incidence to the level of uninfected controls.ConclusionsOur studies provide evidence that H. pyloriinfection is a strong causal promoter of colorectal carcinogenesis. Therefore, implementation of H. pyloristatus into preventive measures of CRC should be considered.

A substantial part of COVID-19-patients suffers from multi-organ failure (MOF). We report on an 80-year old patient with pulmonary, renal, circulatory, and hepatic failure. We decided against the use of extracorporeal membrane oxygenation (ECMO) due to old age and a SOFA-score of 13. However, the patient was continuously treated with the extracorporeal multi-organ- “ADVanced Organ Support” (ADVOS) device (ADVITOS GmbH, Munich, Germany). During eight 24h-treatment-sessions blood flow (100–300 mL/min), dialysate flow (160–320 mL/min) and dialysate pH (7.6–9.0) were adapted to optimize arterial PaCO2and pH. Effective CO2removal and correction of acidosis could be demonstrated by mean arterial- versus post-dialyzer values of pCO2(68.7 ± 13.8 vs. 26.9 ± 11.6 mmHg; p< 0.001). The CO2-elimination rate was 48 ± 23mL/min. The initial vasopressor requirement could be reduced in parallel to pH-normalization. Interruptions of ADVOS-treatment repeatedly resulted in reversible deteriorations of paCO2and pH. After 95 h of continuous extracorporeal decarboxylating therapy the patient had markedly improved circulatory parameters compared to baseline. In the context of secondary pulmonary infection and progressive liver failure, the patient had a sudden cardiac arrest. In accordance with the presumed patient will, we decided against mechanical resuscitation. Irrespective of the outcome we conclude that extracorporeal CO2removal and multiorgan-support were feasible in this COVID-19-patient. Combined and less invasive approaches such as ADVOS might be considered in old-age-COVID-19 patients with MOF.

Background and aimsThe gastric epithelium undergoes continuous turnover. Corpus epithelial stem cells located in the gastric isthmus serve as a source of tissue self-renewal. We recently identified the transcription factor Mist1 as a marker for this corpus stem cell population that can give rise to cancer. The aim here was to investigate the regulation of the Mist1+ stem cells in the response to gastric injury and inflammation.MethodsWe used Mist1CreERT;R26-Tdtomato mice in two models of injury and inflammation: the acetic acid-induced ulcer and infection with Helicobacter felis. We analysed lineage tracing at both early (7 to 30 days) and late (30 to 90 days) time points. Mist1CreERT;R26-Tdtomato;Lgr5DTR-eGFP mice were used to ablate the corpus basal Lgr5+ cell population. Constitutional and conditional Wnt5a knockout mice were used to investigate the role of Wnt5a in wound repair and lineage tracing from the Mist1+ stem cells.ResultsIn both models of gastric injury, Mist1+ isthmus stem cells more rapidly proliferate and trace entire gastric glands compared with the normal state. In regenerating tissue, the number of traced gastric chief cells was significantly reduced, and ablation of Lgr5+ chief cells did not affect Mist1-derived lineage tracing and tissue regeneration. Genetic deletion of Wnt5a impaired proliferation in the gastric isthmus and lineage tracing from Mist1+ stem cells. Similarly, depletion of innate lymphoid cells, the main source of Wnt5a, also resulted in reduced proliferation and Mist1+ isthmus cell tracing.ConclusionGastric Mist1+ isthmus cells are the main supplier of regenerated glands and are activated in part through Wnt5a pathway.

While adult pancreatic stem cells are thought not to exist, it is now appreciated that the acinar compartment harbors progenitors, including tissue-repairing facultative progenitors (FPs). Here, we study a pancreatic acinar population marked by trefoil factor 2 (Tff2) expression. Long-term lineage tracing and single-cell RNA sequencing (scRNA-seq) analysis of Tff2-DTR-CreERT2-targeted cells defines a transit-amplifying progenitor (TAP) population that contributes to normal homeostasis. Following acute and chronic injury, Tff2+cells, distinct from FPs, undergo depopulation but are eventually replenished. At baseline, oncogenic KrasG12D-targeted Tff2+cells are resistant to PDAC initiation. However, KrasG12Dactivation in Tff2+cells leads to survival and clonal expansion following pancreatitis and a cancer stem/progenitor cell-like state. Selective ablation of Tff2+cells prior to KrasG12Dactivation in Mist1+acinar or Dclk1+FP cells results in enhanced tumorigenesis, which can be partially rescued by adenoviral Tff2 treatment. Together, Tff2 defines a pancreatic TAP population that protects against Kras-driven carcinogenesis.

ABSTRACTThere 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. 16S 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. We 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., Parabacteroidesssp.). 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. Gut 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.

Dabigatran-etexilate (DE) recently has been approved for stroke prevention in atrial fibrillation. However, lack of effective antagonists represents a major concern in the event of intracerebral hemorrhage (ICH). The aims of the present study were to establish a murine model of ICH associated with dabigatran, and to test the efficacy of different hemostatic factors in preventing hematoma growth.

Myeloid-biased hematopoietic stem cells (MB-HSCs) play critical roles in recovery from injury, but little is known about how they are regulated within the bone marrow niche. Here we describe an auto-/paracrine physiologic circuit that controls quiescence of MB-HSCs and hematopoietic progenitors marked by histidine decarboxylase (Hdc). Committed Hdc+myeloid cells lie in close anatomical proximity to MB-HSCs and produce histamine, which activates the H2receptor on MB-HSCs to promote their quiescence and self-renewal. Depleting histamine-producing cells enforces cell cycle entry, induces loss of serial transplant capacity, and sensitizes animals to chemotherapeutic injury. Increasing demand for myeloid cells via lipopolysaccharide (LPS) treatment specifically recruits MB-HSCs and progenitors into the cell cycle; cycling MB-HSCs fail to revert into quiescence in the absence of histamine feedback, leading to their depletion, while an H2agonist protects MB-HSCs from depletion after sepsis. Thus, histamine couples lineage-specific physiological demands to intrinsically primed MB-HSCs to enforce homeostasis.

ABSTRACTThe colorectal tumor microenvironment contains a diverse population of myeloid cells that are recruited and converted to immunosuppressive cells, thus facilitating tumor escape from immunoediting. We have identified a genetically and functionally distinct subset of dynamic bone marrow myeloid cells that are characterized by histidine decarboxylase (HDC) expression. Lineage tracing in Hdc-CreERT2;R26-LSL-tdTomato mice revealed that in homeostasis, there is a strong bias by HDC+myeloid cells toward the CD11b+Ly6Ghigranulocytic lineage, which was accelerated during azoxymethane/dextran sodium sulfate (AOM/DSS)-induced colonic carcinogenesis. More importantly, HDC+myeloid cells strongly promoted colonic tumorigenesis, and colon tumor progression was profoundly suppressed by diphtheria toxin A (DTA)-mediated depletion of HDC+granulocytic myeloid cells. In addition, tumor infiltration by Foxp3+regulatory T cells (Tregs) was markedly impaired following HDC+myeloid cell depletion. We identified an HDC+myeloid-derived Cxcl13/Cxcr5 axis that mediated Foxp3 expression and Treg proliferation. Ablation of HDC+myeloid cells or disruption of the Cxcl13/Cxcr5 axis by gene knockdown impaired the production and recruitment of Tregs. Cxcl13 induction of Foxp3 expression in Tregs during tumorigenesis was associated with Stat3 phosphorylation. Overall, HDC+granulocytic myeloid cells affect CD8+T cells directly and indirectly through the modulation of Tregs and thus appear to play key roles in suppressing tumoricidal immunity.