The Catalytic Subunit of Protein Phosphatase 1 Gamma Regulates Thrombin-Induced Murine Platelet αIIbβ3 Function

BACKGROUND:Hemostasis and thrombosis are regulated by agonist-induced activation of platelet integrin alpha(IIb)beta(3). Integrin activation, in turn is mediated by cellular signaling via protein kinases and protein phosphatases. Although the catalytic subunit of protein phosphatase 1 (PP1c) interacts with alpha(IIb)beta(3), the role of PP1c in platelet reactivity is unclear. METHODOLOGY/PRINCIPAL FINDINGS:Using gamma isoform of PP1c deficient mice (PP1cgamma(-/-)), we show that the platelets have moderately decreased soluble fibrinogen binding and aggregation to low concentrations of thrombin or protease-activated receptor 4 (PAR4)-activating peptide but not to adenosine diphosphate (ADP), collagen or collagen-related peptide (CRP). Thrombin-stimulated PP1cgamma(-/-) platelets showed decreased alpha(IIb)beta(3) activation despite comparable levels of alpha(IIb)beta(3), PAR3, PAR4 expression and normal granule secretion. Functions regulated by outside-in integrin alpha(IIb)beta(3) signaling like adhesion to immobilized fibrinogen and clot retraction were not altered in PP1cgamma(-/-) platelets. Thrombus formation induced by a light/dye injury in the cremaster muscle venules was significantly delayed in PP1cgamma(-/-) mice. Phosphorylation of glycogen synthase kinase (GSK3)beta-serine 9 that promotes platelet function, was reduced in thrombin-stimulated PP1cgamma(-/-) platelets by an AKT independent mechanism. Inhibition of GSK3beta partially abolished the difference in fibrinogen binding between thrombin-stimulated wild type and PP1cgamma(-/-) platelets. CONCLUSIONS/SIGNIFICANCE:These studies illustrate a role for PP1cgamma in maintaining GSK3beta-serine9 phosphorylation downstream of thrombin signaling and promoting thrombus formation via fibrinogen binding and platelet aggregation

The bacterial microbiota regulates normal hematopoiesis via metabolite-induced type 1 interferon signaling

Antibiotic therapy, especially when administered long term, is associated with adverse hematologic effects such as cytopenia. Signals from the intestinal microbiota are critical to maintain normal hematopoiesis, and antibiotics can cause bone marrow suppression through depletion of the microbiota. We reported previously that STAT1 signaling is necessary for microbiota-dependent hematopoiesis, but the precise mechanisms by which the gut microbiota signals to the host bone marrow to regulate hematopoiesis remain undefined. We sought to identify the cell type(s) through which STAT1 promotes microbiota-mediated hematopoiesis and to elucidate which upstream signaling pathways trigger STAT1 signaling. Using conditional knockout and chimeric mice, we found that the microbiota induced STAT1 signaling in non-myeloid hematopoietic cells to support hematopoiesis and that STAT1 signaling was specifically dependent on type I interferons (IFNs). Indeed, basal type I IFN signaling was reduced in hematopoietic progenitor cells with antibiotic treatment. In addition, we discovered that oral administration of a commensal-derived product, NOD1 ligand, rescues the hematopoietic defects induced by antibiotics in mice. Using metabolomics, we identified additional microbially produced candidates that can stimulate type I IFN signaling to potentially rescue the hematopoietic defects induced by antibiotics, including phosphatidylcholine and γ-glutamylalanine. Overall, our studies define a signaling pathway through which microbiota promotes normal hematopoiesis and identify microbial metabolites that may serve as therapeutic agents to ameliorate antibiotic-induced bone marrow suppression and cytopenia

Patient Descriptions of Rectal Effluents May Help to Predict the Quality of Bowel Preparation With Photographic Examples

Background/AimsPrevious studies have suggested a weak correlation between self-reported rectal effluent status and bowel preparation quality. We aim to evaluate whether photographic examples of rectal effluents could improve the correlation between patient descriptions of rectal effluents and bowel preparation quality.MethodsBefore colonoscopy, patients were asked to describe the nature of their last three rectal effluents. Photographic examples of rectal effluents were provided as a reference for scoring. Bowel preparation was subsequently assessed by a single endoscopist using a global preparation assessment scale. Preparation outcomes were grouped into two levels (excellent to good vs. fair to inadequate). Both univariate and multivariate logistic regression models were used to find any association between bowel preparation quality and patient characteristics.ResultsA total of 138 patients completed the questionnaires. The mean age was 56.5±10.4 years. The mean sum of the last three rectal effluent scores was 5.9±2.0. Higher rectal effluent scores (odds ratio [OR], 0.82; P=0.043) and the presence of diverticula (OR, 0.16; P<0.001) were risk factors for suboptimal preparation.ConclusionsPhotographic example-guided patient descriptions of rectal effluents showed a statistically significant association with bowel preparation quality. However, clinical significance seemed to be low. The presence of diverticula was an independent predictive factor for suboptimal bowel preparation quality

The Early Stage of Bacterial Genome-Reductive Evolution in the Host

The equine-associated obligate pathogen Burkholderia mallei was developed by reductive evolution involving a substantial portion of the genome from Burkholderia pseudomallei, a free-living opportunistic pathogen. With its short history of divergence (∼3.5 myr), B. mallei provides an excellent resource to study the early steps in bacterial genome reductive evolution in the host. By examining 20 genomes of B. mallei and B. pseudomallei, we found that stepwise massive expansion of IS (insertion sequence) elements ISBma1, ISBma2, and IS407A occurred during the evolution of B. mallei. Each element proliferated through the sites where its target selection preference was met. Then, ISBma1 and ISBma2 contributed to the further spread of IS407A by providing secondary insertion sites. This spread increased genomic deletions and rearrangements, which were predominantly mediated by IS407A. There were also nucleotide-level disruptions in a large number of genes. However, no significant signs of erosion were yet noted in these genes. Intriguingly, all these genomic modifications did not seriously alter the gene expression patterns inherited from B. pseudomallei. This efficient and elaborate genomic transition was enabled largely through the formation of the highly flexible IS-blended genome and the guidance by selective forces in the host. The detailed IS intervention, unveiled for the first time in this study, may represent the key component of a general mechanism for early bacterial evolution in the host

Efficacy and safety of epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) monotherapy for advanced EGFR-mutated non-small cell lung cancer: systematic review and meta-analysis

OBJECTIVE: It is controversial whether there is efficacy or safety benefit of epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) in advanced EGFR-mutated non-small cell lung cancer (NSCLC) compared to standard chemotherapy. We aim to assess the efficacy and safety of EGFR-TKIs compared to other chemotherapeutics in EGFR-mutated NSCLC. MATERIALS AND METHODS: Up to April 27th, 2020, PubMed, Embase, Medline, Scopus, Cochrane library, and ClinicalTrials.gov were searched for articles or trials meeting the inclusion criteria. After filtering, 230 eligible studies were initially identified. Data extraction followed PRISMA and included outcomes were progression-free survival (PFS), overall survival (OS), and severe adverse events (SAEs). Direct and indirect meta-analyses were generated in the context of log-linear mixed-effects models, with fixed effects for each relative comparison and random effects for each study. RESULTS: The results showed that EGFR-TKI therapy had improved PFS with a hazard ratio (HR) of 0.40 (95% CI: 0.36-0.44, p<0.001) compared to standard chemotherapy. Nevertheless, the EGFR-TKIs showed no benefit on OS (HR: 0.96, 95% CI: 0.83-1.10, p=0.556). In the analysis of adverse events, EGFR-TKIs had fewer SAEs than standard chemotherapy (HR: 0.29, 95% CI: 0.26-0.33, p<0.001). CONCLUSIONS: Our systemic review indicates that EGFR-TKI therapy has improved PFS, and reduced SAEs compared to standard chemotherapy in advanced EGFR-mutated NSCLC

Transient Abnormal Myelopoeisis and Mosaic down Syndrome in a Phenotypically Normal Newborn

Transient abnormal myelopoiesis (TAM) is a common and potentially fatal neonatal complication of newborn babies with Down syndrome (DS). Children born with mosaic DS are also at risk of developing TAM. However, due to their variable phenotypes, early identification of patients with mosaic DS may be difficult; thus, early diagnosis of TAM is just as challenging. In this report, we describe a case of a phenotypically normal newborn who presented with concerns for neonatal leukemia. The diagnosis of mosaic DS and TAM was confirmed with abnormal GATA1 mutation testing, highlighting the importance of early GATA1 mutation testing in newborn leukemia with high suspicion for TAM

Broad-Spectrum Antibiotics Deplete Bone Marrow Regulatory T Cells

Bone marrow suppression, including neutropenia, is a major adverse effect of prolonged antibiotic use that impairs the clinical care and outcomes of patients with serious infections. The mechanisms underlying antibiotic-mediated bone marrow suppression remain poorly understood, with initial evidence indicating that depletion of the intestinal microbiota is an important factor. Based on our earlier studies of blood and bone marrow changes in a mouse model of prolonged antibiotic administration, we studied whether changes in megakaryocytes or regulatory T cells (Tregs), two cell types that are critical in the maintenance of hematopoietic stem cells, contribute to antibiotic-mediated bone marrow suppression. Despite increased platelet numbers, megakaryocytes were unchanged in the bone marrow of antibiotic-treated mice; however, Tregs were found to be significantly depleted. Exogenous addition of Tregs was insufficient to rescue the function of bone marrow from antibiotic-treated mice in both colony formation and transplantation assays. These findings indicate that the intestinal microbiota support normal Treg development to protect healthy hematopoiesis, but that the restoration of Tregs alone is insufficient to restore normal bone marrow function

Broad-Spectrum Antibiotics Deplete Bone Marrow Regulatory T Cells

Bone marrow suppression, including neutropenia, is a major adverse effect of prolonged antibiotic use that impairs the clinical care and outcomes of patients with serious infections. The mechanisms underlying antibiotic-mediated bone marrow suppression remain poorly understood, with initial evidence indicating that depletion of the intestinal microbiota is an important factor. Based on our earlier studies of blood and bone marrow changes in a mouse model of prolonged antibiotic administration, we studied whether changes in megakaryocytes or regulatory T cells (Tregs), two cell types that are critical in the maintenance of hematopoietic stem cells, contribute to antibiotic-mediated bone marrow suppression. Despite increased platelet numbers, megakaryocytes were unchanged in the bone marrow of antibiotic-treated mice; however, Tregs were found to be significantly depleted. Exogenous addition of Tregs was insufficient to rescue the function of bone marrow from antibiotic-treated mice in both colony formation and transplantation assays. These findings indicate that the intestinal microbiota support normal Treg development to protect healthy hematopoiesis, but that the restoration of Tregs alone is insufficient to restore normal bone marrow function