The Cysteine Rich Necrotrophic Effector SnTox1 Produced by Stagonospora nodorum Triggers Susceptibility of Wheat Lines Harboring Snn1

The wheat pathogen Stagonospora nodorum produces multiple necrotrophic effectors (also called host-selective toxins) that promote disease by interacting with corresponding host sensitivity gene products. SnTox1 was the first necrotrophic effector identified in S. nodorum, and was shown to induce necrosis on wheat lines carrying Snn1. Here, we report the molecular cloning and validation of SnTox1 as well as the preliminary characterization of the mechanism underlying the SnTox1-Snn1 interaction which leads to susceptibility. SnTox1 was identified using bioinformatics tools and verified by heterologous expression in Pichia pastoris. SnTox1 encodes a 117 amino acid protein with the first 17 amino acids predicted as a signal peptide, and strikingly, the mature protein contains 16 cysteine residues, a common feature for some avirulence effectors. The transformation of SnTox1 into an avirulent S. nodorum isolate was sufficient to make the strain pathogenic. Additionally, the deletion of SnTox1 in virulent isolates rendered the SnTox1 mutated strains avirulent on the Snn1 differential wheat line. SnTox1 was present in 85% of a global collection of S. nodorum isolates. We identified a total of 11 protein isoforms and found evidence for strong diversifying selection operating on SnTox1. The SnTox1-Snn1 interaction results in an oxidative burst, DNA laddering, and pathogenesis related (PR) gene expression, all hallmarks of a defense response. In the absence of light, the development of SnTox1-induced necrosis and disease symptoms were completely blocked. By comparing the infection processes of a GFP-tagged avirulent isolate and the same isolate transformed with SnTox1, we conclude that SnTox1 may play a critical role during fungal penetration. This research further demonstrates that necrotrophic fungal pathogens utilize small effector proteins to exploit plant resistance pathways for their colonization, which provides important insights into the molecular basis of the wheat-S. nodorum interaction, an emerging model for necrotrophic pathosystems

Immune checkpoint inhibition in sepsis: a Phase 1b randomized study to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of nivolumab

PurposeSepsis-associated immunosuppression increases hospital-acquired infection and viral reactivation risk. A key underlying mechanism is programmed cell death protein-1 (PD-1)-mediated T-cell function impairment. This is one of the first clinical safety and pharmacokinetics (PK) assessments of the anti-PD-1 antibody nivolumab and its effect on immune biomarkers in sepsis.MethodsRandomized, double-blind, parallel-group, Phase 1b study in 31 adults at 10 US hospital ICUs with sepsis diagnosed ≥ 24 h before study treatment, ≥ 1 organ dysfunction, and absolute lymphocyte count ≤ 1.1 × 103 cells/μL. Participants received one nivolumab dose [480 mg (n = 15) or 960 mg (n = 16)]; follow-up was 90 days. Primary endpoints were safety and PK parameters.ResultsTwelve deaths occurred [n = 6 per study arm; 40% (480 mg) and 37.5% (960 mg)]. Serious AEs occurred in eight participants [n = 1, 6.7% (480 mg); n = 7, 43.8% (960 mg)]. AEs considered by the investigator to be possibly drug-related and immune-mediated occurred in five participants [n = 2, 13.3% (480 mg); n = 3, 18.8% (960 mg)]. Mean ± SD terminal half-life was 14.7 ± 5.3 (480 mg) and 15.8 ± 7.9 (960 mg) days. All participants maintained > 90% receptor occupancy (RO) 28 days post-infusion. Median (Q1, Q3) mHLA-DR levels increased to 11,531 (6528, 19,495) and 11,449 (6225, 16,698) mAbs/cell in the 480- and 960-mg arms by day 14, respectively. Pro-inflammatory cytokine levels did not increase.ConclusionsIn this sepsis population, nivolumab administration did not result in unexpected safety findings or indicate any 'cytokine storm'. The PK profile maintained RO > 90% for ≥ 28 days. Further efficacy and safety studies are warranted. TRIAL REGISTRATION NUMBER (CLINICALTRIALS.GOV): NCT02960854

Same data, different conclusions: Radical dispersion in empirical results when independent analysts operationalize and test the same hypothesis

In this crowdsourced initiative, independent analysts used the same dataset to test two hypotheses regarding the effects of scientists’ gender and professional status on verbosity during group meetings. Not only the analytic approach but also the operationalizations of key variables were left unconstrained and up to individual analysts. For instance, analysts could choose to operationalize status as job title, institutional ranking, citation counts, or some combination. To maximize transparency regarding the process by which analytic choices are made, the analysts used a platform we developed called DataExplained to justify both preferred and rejected analytic paths in real time. Analyses lacking sufficient detail, reproducible code, or with statistical errors were excluded, resulting in 29 analyses in the final sample. Researchers reported radically different analyses and dispersed empirical outcomes, in a number of cases obtaining significant effects in opposite directions for the same research question. A Boba multiverse analysis demonstrates that decisions about how to operationalize variables explain variability in outcomes above and beyond statistical choices (e.g., covariates). Subjective researcher decisions play a critical role in driving the reported empirical results, underscoring the need for open data, systematic robustness checks, and transparency regarding both analytic paths taken and not taken. Implications for organizations and leaders, whose decision making relies in part on scientific findings, consulting reports, and internal analyses by data scientists, are discussed