Haemophagocytic lymphohistiocytosis in adult critical care

Haemophagocytic lymphohistiocytosis (HLH) is a syndrome of severe immune dysregulation, characterised by extreme inflammation, fever, cytopaenias and organ dysfunction. HLH can be triggered by conditions such as infection, auto-immune disease and malignancy, amongst others. Both a familial and a secondary form have been described, the latter being increasingly recognised in adult patients with critical illness. HLH is difficult to diagnose, often underrecognised and carries a high mortality. Patients can present in a very similar fashion to sepsis and the two syndromes can co-exist and overlap, yet HLH requires specific immunosuppressive therapy. HLH should be actively excluded in patients with presumed sepsis who either lack a clear focus of infection or who are not responding to energetic infection management. Elevated serum ferritin is a key biomarker that may indicate the need for further investigations for HLH and can guide treatment. Early diagnosis and a multidisciplinary approach to HLH management may save lives

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine

[This corrects the article DOI: 10.1186/s13054-016-1208-6.]

Critical care outcomes in patients with pre-existing pulmonary hypertension: insights from the ASPIRE registry

Pulmonary Hypertension (PH) is a life-shortening condition characterised by episodes of decompensation precipitated by factors such as disease progression, arrhythmias and sepsis. Surgery and pregnancy also place additional strain on the right ventricle. Data on critical care management in patients with pre-existing PH are scarce. We conducted a retrospective observational study of a large cohort of patients admitted to the critical care unit of a national referral centre between 2000–17 to establish acute mortality, evaluate predictors of in-hospital mortality and establish longer-term outcomes in survivors to hospital discharge. 242 critical care admissions involving 206 patients were identified. Hospital survival was 59.3%, 94% and 92% for patients admitted for medical, surgical or obstetric reasons. Medical patients had more severe physiological and laboratory perturbations than patients admitted following surgical or obstetric interventions. Higher APACHE II score, age and lactate, and lower SpO2/FiO2, platelet count and sodium level were identified as independent predictors of hospital mortality. An exploratory risk score, OPALS (Oxygen (SpO2:FiO2), ≤185; Platelets, ≤196×109·L−1; Age, ≥37.5 years; Lactate, ≥2.45 mmol·L−1; Sodium, ≤130.5 mmol·L−1), identified medical patients at increasing risk of hospital mortality. One of nine patients (11%) who were invasively ventilated for medical decompensation and 50% of patients receiving renal replacement therapy left hospital alive. There was no significant difference in exercise capacity or functional class between follow-up and pre-admission in patients who survived to discharge. These data have clinical utility in guiding critical care management of patients with known PH. The exploratory OPALS score requires validation

Whole-genome sequencing reveals host factors underlying critical COVID-19

Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2–4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease

Common, low-frequency, rare, and ultra-rare coding variants contribute to COVID-19 severity

The combined impact of common and rare exonic variants in COVID-19 host genetics is currently insufficiently understood. Here, common and rare variants from whole-exome sequencing data of about 4000 SARS-CoV-2-positive individuals were used to define an interpretable machine-learning model for predicting COVID-19 severity. First, variants were converted into separate sets of Boolean features, depending on the absence or the presence of variants in each gene. An ensemble of LASSO logistic regression models was used to identify the most informative Boolean features with respect to the genetic bases of severity. The Boolean features selected by these logistic models were combined into an Integrated PolyGenic Score that offers a synthetic and interpretable index for describing the contribution of host genetics in COVID-19 severity, as demonstrated through testing in several independent cohorts. Selected features belong to ultra-rare, rare, low-frequency, and common variants, including those in linkage disequilibrium with known GWAS loci. Noteworthily, around one quarter of the selected genes are sex-specific. Pathway analysis of the selected genes associated with COVID-19 severity reflected the multi-organ nature of the disease. The proposed model might provide useful information for developing diagnostics and therapeutics, while also being able to guide bedside disease management. © 2021, The Author(s)

Genetic mechanisms of critical illness in Covid-19.

Host-mediated lung inflammation is present,1 and drives mortality,2 in critical illness caused by Covid-19. Host genetic variants associated with critical illness may identify mechanistic targets for therapeutic development.3 Here we report the results of the GenOMICC (Genetics Of Mortality In Critical Care) genome-wide association study(GWAS) in 2244 critically ill Covid-19 patients from 208 UK intensive care units (ICUs). We identify and replicate novel genome-wide significant associations, on chr12q24.13 (rs10735079, p=1.65 [Formula: see text] 10-8) in a gene cluster encoding antiviral restriction enzyme activators (OAS1, OAS2, OAS3), on chr19p13.2 (rs2109069, p=2.3 [Formula: see text] 10-12) near the gene encoding tyrosine kinase 2 (TYK2), on chr19p13.3 (rs2109069, p=3.98 [Formula: see text] 10-12) within the gene encoding dipeptidyl peptidase 9 (DPP9), and on chr21q22.1 (rs2236757, p=4.99 [Formula: see text] 10-8) in the interferon receptor gene IFNAR2. We identify potential targets for repurposing of licensed medications: using Mendelian randomisation we found evidence in support of a causal link from low expression of IFNAR2, and high expression of TYK2, to life-threatening disease; transcriptome-wide association in lung tissue revealed that high expression of the monocyte/macrophage chemotactic receptor CCR2 is associated with severe Covid-19. Our results identify robust genetic signals relating to key host antiviral defence mechanisms, and mediators of inflammatory organ damage in Covid-19. Both mechanisms may be amenable to targeted treatment with existing drugs. Large-scale randomised clinical trials will be essential before any change to clinical practice

Whole-genome sequencing reveals host factors underlying critical COVID-19

Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2,3,4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease

Sulfasalazine reduces bile acid induced apoptosis in human hepatoma cells and perfused rat livers

BACKGROUND: Bile acid induced apoptosis in hepatocytes can be antagonised by nuclear factor κB (NFκB) dependent survival pathways. Sulfasalazine modulates NFκB in different cell types. We aimed to determine the effects of sulfasalazine and its metabolites sulfapyridine and 5‐aminosalicylic acid (5‐ASA) on bile acid induced apoptosis in hepatocytes. METHODS: Apoptosis was determined by caspase assays and immunoblotting, NFκB activation by electrophoretic mobility shift assay and reporter gene assays, generation of reactive oxygen species (ROS) fluorometrically, bile secretion gravimetrically, and bile acid uptake radiochemically and by gas chromatography in HepG2‐Ntcp cells and isolated perfused rat livers. RESULTS: Glycochenodeoxycholic acid (GCDCA 75 µmol/l) induced apoptosis was reduced by sulfasalazine dose dependently (1–1000 µmol/l) in HepG2‐Ntcp cells whereas its metabolites 5‐ASA and sulfapyridine had no effect. Sulfasalazine significantly reduced GCDCA induced activation of caspases 9 and 3. In addition, sulfasalazine activated NFκB and decreased GCDCA induced generation of ROS. Bile acid uptake was competitively inhibited by sulfasalazine. In perfused rat livers, GCDCA (25 µmol/l) induced liver injury and extensive hepatocyte apoptosis were significantly reduced by simultaneous administration of 100 µmol/l sulfasalazine: lactate dehydrogenase and glutamate‐pyruvate transaminase activities were reduced by 82% and 87%, respectively, and apoptotic hepatocytes were observed only occasionally. GCDCA uptake was reduced by 45 (5)% when sulfasalazine was coadministered. However, when 50% of GCDCA (12.5 µmol/l) was administered alone, marked hepatocyte apoptosis and liver injury were again observed, questioning the impact of reduced GCDCA uptake for the antiapoptotic effect of sulfasalazine. CONCLUSION: Sulfasalazine is a potent inhibitor of GCDCA induced hepatocyte apoptosis in vitro and in the intact liver