Systems-wide dissection of organic acid assimilation in Pseudomonas aeruginosa reveals a novel path to underground metabolism

The human pathogen Pseudomonas aeruginosa (Pa¬) is one of the most frequent and severe causes of nosocomial infection. This organism is also a major cause of airway infections in people with cystic fibrosis (CF). Pa is known to have a remarkable metabolic plasticity, allowing it to thrive in diverse environmental conditions and ecological niches, yet little is known about the central metabolic pathways which sustain its growth during infection, or precisely how these pathways operate. In this work, we used a combination of ‘omics approaches (transcriptomics, proteomics, metabolomics and 13C-fluxomics) and reverse genetics to provide a systems-level insight into how the infection-relevant organic acids, succinate and propionate, are metabolized by Pa. Moreover, through structural and kinetic analysis of the 2-methylcitrate synthase (PrpC) and its paralogue, citrate synthase (GltA), we show how these two crucial enzymatic steps are interconnected in Pa organic acid assimilation. We found that Pa can rapidly adapt to the loss of GltA function by acquiring mutations in a transcriptional repressor, which then de-represses prpC expression. Our findings provide a clear example of how ‘underground metabolism’, facilitated by enzyme substrate promiscuity, “rewires” Pa metabolism, allowing it to overcome the loss of a crucial enzyme. This pathogen-specific knowledge is critical for the advancement of a model-driven framework to target bacterial central metabolism

Allelic variation in CRHR1 predisposes to panic disorder : evidence for biased fear processing

This work is part of the German multicenter trial ‘Mechanisms of Action in CBT (MAC)’. The MAC study is funded by the German Federal Ministry of Education and Research (BMBF; project no. 01GV0615) as part of the BMBF Psychotherapy Research Funding Initiative. The study was further supported by the DFG (Grant RE1632/5-1 and KFO 125 to AR; SFB TRR 58 Z02 to JD, PP and AR; C02 to JD and KD; DE357/4-1 to JD, AR, JR and AH; RTG 1256 to AR, JD and PP; IZKF-Würzburg Z-6 to HW).Corticotropin releasing hormone (CRH) is a major regulator of the hypothalamicpituitary-adrenal (HPA) axis. Binding to its receptor CRHR1 triggers the downstream release of cortisol, a hormone needed for regulation of stress responses. Biochemical, behavioral and genetic studies revealed CRHR1 as a possible candidate gene for mood and anxiety disorders. Here, we aimed to evaluate CRHR1 as a candidate molecule in panic disorder (PD). Allelic variation throughout the CRHR1 gene was captured by 9 selected single nucleotide polymorphisms (SNPs); these were genotyped in 531 matched case/control pairs (discovery sample (n=239); replication sample (n=292)). Four SNPs were found to be associated with PD, in at least one sub-sample. The minor alleles of rs17689918 and rs17689966 were found to significantly increase risk for PD in females of the discovery, the replication and the combined sample, both withstanding correction for multiple testing (prs17689918=1.3*10-4; prs17689966=0.042). Expressional analysis demonstrated that both minor alleles of rs17689918 and rs17689966 significantly decreased CRHR1 mRNA in the forebrain and amygdala. Bioinformatical analysis revealed a high proportion of differential neuro-relevant transcription factor binding possibly underlying expression changes. When investigating the neural correlates underlying this association, risk allele carriers of rs17689918 and rs17689966 showed aberrant differential conditioning and safety signal processing arguing for predominant generalization of fear and hence anxious apprehension. Furthermore, the minor risk (A) allele of rs17689918 led to less flight behavior during fear provoking situations, but rather increased anxious apprehension and went along with increased anxiety sensitivity. Thus, reduced CRHR1 expression driven by CRHR1 risk allele leads to a phenotype characterized by a fear bias and hence sustained fear. These results strengthen the role of CRHR1 in PD and clarify the mechanisms by which genetic variation in CRHR1 is linked to this disorder.PostprintPeer reviewe

Association of Country Income Level With the Characteristics and Outcomes of Critically Ill Patients Hospitalized With Acute Kidney Injury and COVID-19

Introduction: Acute kidney injury (AKI) has been identified as one of the most common and significant problems in hospitalized patients with COVID-19. However, studies examining the relationship between COVID-19 and AKI in low- and low-middle income countries (LLMIC) are lacking. Given that AKI is known to carry a higher mortality rate in these countries, it is important to understand differences in this population. Methods: This prospective, observational study examines the AKI incidence and characteristics of 32,210 patients with COVID-19 from 49 countries across all income levels who were admitted to an intensive care unit during their hospital stay. Results: Among patients with COVID-19 admitted to the intensive care unit, AKI incidence was highest in patients in LLMIC, followed by patients in upper-middle income countries (UMIC) and high-income countries (HIC) (53%, 38%, and 30%, respectively), whereas dialysis rates were lowest among patients with AKI from LLMIC and highest among those from HIC (27% vs. 45%). Patients with AKI in LLMIC had the largest proportion of community-acquired AKI (CA-AKI) and highest rate of in-hospital death (79% vs. 54% in HIC and 66% in UMIC). The association between AKI, being from LLMIC and in-hospital death persisted even after adjusting for disease severity. Conclusions: AKI is a particularly devastating complication of COVID-19 among patients from poorer nations where the gaps in accessibility and quality of healthcare delivery have a major impact on patient outcomes

Thrombotic and hemorrhagic complications of COVID-19 in adults hospitalized in high-income countries compared with those in adults hospitalized in low- and middle-income countries in an international registry

Background: COVID-19 has been associated with a broad range of thromboembolic, ischemic, and hemorrhagic complications (coagulopathy complications). Most studies have focused on patients with severe disease from high-income countries (HICs). Objectives: The main aims were to compare the frequency of coagulopathy complications in developing countries (low- and middle-income countries [LMICs]) with those in HICs, delineate the frequency across a range of treatment levels, and determine associations with in-hospital mortality. Methods: Adult patients enrolled in an observational, multinational registry, the International Severe Acute Respiratory and Emerging Infections COVID-19 study, between January 1, 2020, and September 15, 2021, met inclusion criteria, including admission to a hospital for laboratory-confirmed, acute COVID-19 and data on complications and survival. The advanced-treatment cohort received care, such as admission to the intensive care unit, mechanical ventilation, or inotropes or vasopressors; the basic-treatment cohort did not receive any of these interventions. Results: The study population included 495,682 patients from 52 countries, with 63% from LMICs and 85% in the basic treatment cohort. The frequency of coagulopathy complications was higher in HICs (0.76%-3.4%) than in LMICs (0.09%-1.22%). Complications were more frequent in the advanced-treatment cohort than in the basic-treatment cohort. Coagulopathy complications were associated with increased in-hospital mortality (odds ratio, 1.58; 95% CI, 1.52-1.64). The increased mortality associated with these complications was higher in LMICs (58.5%) than in HICs (35.4%). After controlling for coagulopathy complications, treatment intensity, and multiple other factors, the mortality was higher among patients in LMICs than among patients in HICs (odds ratio, 1.45; 95% CI, 1.39-1.51). Conclusion: In a large, international registry of patients hospitalized for COVID-19, coagulopathy complications were more frequent in HICs than in LMICs (developing countries). Increased mortality associated with coagulopathy complications was of a greater magnitude among patients in LMICs. Additional research is needed regarding timely diagnosis of and intervention for coagulation derangements associated with COVID-19, particularly for limited-resource settings