Transcriptomic clustering of critically ill COVID-19 patients (preprint)

Infections caused by SARS-CoV-2 may cause a severe disease, termed COVID-19, with significant mortality. Host responses to this infection, mainly in terms of systemic inflammation, have emerged as key pathogenetic mechanisms, and their modulation is the only therapeutic strategy that has shown a mortality benefit. Herein, we used peripheral blood transcriptomes of critically-ill COVID-19 patients obtained at admission in an Intensive Care Unit (ICU), to identify two transcriptomic clusters characterized by expression of either interferon-related or immune checkpoint genes, respectively. These profiles have different ICU outcome, in spite of no major clinical differences at ICU admission. A transcriptomic signature was used to identify these clusters in an external validation cohort, yielding similar results. These findings reveal different underlying pathogenetic mechanisms and illustrate the potential of transcriptomics to identify patient endotypes in severe COVID-19, aimed to ultimately personalize their therapies.

IFIH1 rs1990760 variants, systemic inflammation and outcome in critically-ill COVID-19 patients (preprint)

Rationale Outcomes in patients with severe SARS-CoV-2 infection (COVID-19) are conditioned by virus clearance and regulation of inflammation. Variants in IFIH1 , a gene coding the cytoplasmatic RNA sensor MDA5, regulate the response to viral infections. Objective To characterize the impact of IFIH1 rs199076 variants on host response and outcomes after severe COVID-19. Methods Patients admitted to an intensive care unit (ICU) with confirmed COVID-19 were prospectively studied and rs1990760 variants determined. Peripheral blood gene expression, cell populations and immune mediators were measured. Peripheral blood mononuclear cells from healthy volunteers were exposed to an MDA5 agonist and dexamethasone ex-vivo , and changes in gene expression assessed. ICU discharge and hospital death were modelled using rs1990760 variants and dexamethasone as factors in this cohort and in-silico clinical trials. Measurements and Main Results 227 patients were studied. Patients with the IFIH1 rs1990760 TT variant showed a lower expression of inflammation-related pathways, an anti-inflammatory cell profile and lower concentrations of pro-inflammatory mediators. Cells with TT variant exposed to a MDA5 agonist showed an increase in IL6 expression after dexamethasone treatment. All patients with the TT variant not treated with steroids (N=14) survived their ICU stay (HR 2.49, 95% confidence interval 1.29–4.79). Patients with a TT variant treated with dexamethasone (N=50) showed an increased hospital mortality (HR 2.19, 95% confidence interval 1.01–4.87) and serum IL-6. In-silico clinical trials supported these findings. Conclusions COVID-19 patients with the IFIH1 rs1990760 TT variant show an attenuated inflammatory response and better outcomes. Dexamethasone may reverse this anti-inflammatory phenotype.

The CCR5-delta32 variant might explain part of the association between COVID-19 and the chemokine-receptor gene cluster (preprint)

A polymorphism in the LZTFL1 gene located in the chemokine-receptor gene cluster (chromosome 3p) has been associated with the risk of developing COVID-19. The chemokine receptor-5 (CCR5) maps to this region, and the common 32 bp deletion variant ({Delta}32) has been associated with the extent of inflammatory disease and the outcome in several viral diseases. Several studies have also suggested that the pharmacological targeting of CCR5 could reduce the impact of SARS-CoV-2 infection and the severity of COVID-19. We sought to investigate whether this polymorphism was associated with the risk of moderate-severe COVID-19. We genotyped 294 patients who required hospitalization due to COVID-19 (85 were severe cases) and 460 controls. We found a significantly lower frequency of CCR5-{Delta}32 among the COVID-19 patients (0.10 vs 0.18 in controls; p=0.002, OR=0.48, 95%CI=0.29-0.76). The difference was mainly due to the reduced frequency of CCR5-{Delta}32 carriers in the severe, significantly lower than in the non-severe patients (p=0.036). Of note, we did not find deletion-homozygotes among the patients compared to 1% among controls. We also confirmed the association between a LZTFL1 variant and COVID-19. Our study points to CCR5 as a promising target for treatment of COVID-19, but requires validation in additional large cohorts. In confirmed by others, the genetic analysis of CCR5-variants (such as {Delta}32) might help to identify patients with a higher susceptibility to severe COVID-19.

Angiotensin-converting enzyme (ACE1, ACE2) gene variants are associated with COVID19 severity depending on the hypertension status. (preprint)

Background: The Angiotensin system is implicated in the pathogenesis of COVID19. First, ACE2 is the cellular receptor for SARS-COv-2, and expression of the ACE2 gene could regulate the individuals susceptibility to infection. In addition, the balance between ACE1 and ACE activity has been implicated in the pathogenesis of respiratory diseases and could play a role in the severity of COVID19. Functional ACE1 and ACE2 gene polymorphisms have been associated with the risk of cardiovascular and pulmonary diseases, and could thus also contribute to the outcome of COVID19. Methods: We studied 204 COVID19 patients (137 non-severe and 67 severe-ICU cases) and 536 age-matched controls. The ACE1 indel and ACE2 rs2285666 polymorphism were determined. Variables frequencies were compared between the groups by logistic regression. We also sequenced the ACE2 coding nucleotides in a group of patients. Results: Severe COVID19 was associated with hypertension male gender (p<0.001), hypertension (p=0.006), hypercholesterolaemia (p=0.046), and the ACE1-DD genotype (p=0.049). In the multiple logistic regression hypertension (p=0.02, OR=2.26, 95CI=1.12-4.63) and male gender (p=0.002; OR=3.15, 95CI=1.56-6.66) remained as independent significant predictors of severity. The ACE2 polymorphism was not associated with the disease outcome. The ACE2 sequencing showed no coding sequence variants that could explain an increased risk of developing COVID19. Conclusions: Adverse outcome of COVID19 was associated with male gender, hypertension, hypercholesterolemia and the ACE1 genotype. The ACE1-indel was a significant risk factor for severe COVID19, but the effect was dependent on the hypertensive status.

Capillary Electrophoresis of PCR fragments with labelled primers for testing the SARS-Cov-2 (preprint)

BackgroundDue to the huge demand for SARS-Cov-2 determination, alternatives to the standard qtPCR tests are potentially useful for increasing the number of samples screened. Our aim was to develop a direct fluorescent PCR capillary-electrophoresis detection of the viral genome. We validated this approach on several SARS-Cov-2 positive and negative samples. Study designWe isolated the naso-pharingeal RNA from 20 positive and 10 negative samples. The cDNA was synthesised and two fragments of the SARS-Cov-2 were amplified. One of the primers for each pair was 5-end fluorochrome labelled. The amplifications were subjected to capillary electrophoresis in ABI3130 sequencers to visualize the fluorescent peaks. ResultsThe two SARS-Cov-2 fragments were successfully amplified in the positive samples, while the negative samples did not render fluorescent peaks. ConclusionWe describe and alternative method to identify the SARS-Cov-2 genome that could be scaled to the analysis of approximately 100 samples in less than 5 hours. By combining a standard PCR with capillary electrophoresis our approach would overcome the limits imposed to many labs by the qtPCR (lack of reactive and real-time PCR equipment) and increase the testing capacity.