SARS-CoV-2 susceptibility and COVID-19 disease severity are associated with genetic variants affecting gene expression in a variety of tissues

Altered serum concentrations of IL-8, IL-32 and IL-10 in patients with lung impairment 6 months after COVID-19

Post-COVID symptoms are reported in 10-35 % of patients not requiring hospitalization, and in up to 80 % of hospitalized patients and patients with severe disease. The pathogenesis of post-COVID syndrome remains largely unknown. Some evidence suggests that prolonged inflammation has a key role in the pathogenesis of most post-COVID manifestations. We evaluated a panel of inflammatory and immune-mediated cytokines in individuals with altered HRCT features and in patients without any long-term COVID symptoms. Blood samples of 89 adult patients previously hospitalized with COVID-19 were collected and stratified as patients with and without HRCT evidence of fibrotic lung alterations. Serum analyte concentrations of IL-4, IL-2, CXCL10 (IP-10), IL-1β, TNF-α, CCL2 (MCP-1), IL-17A, IL-6, IL-10, IFN-γ, IL-12p70 and TGF-β1 (free active form) were quantified by bead-based multiplex assay. Clinical and functional data were recorded in a database. With the use of machine learning approach, IL-32, IL-8, and IL-10 proved to be associated with the development of HRCT evidence of lung sequelae at follow-up. Direct comparison of cytokine levels in the two groups showed increased levels of IL-32 and decreased levels of IL-8 in patients with lung impairment. After further stratification of patients by severity (severe versus mild/moderate) during hospitalization, IL-10 emerged as the only cytokine showing decreased levels in severe patients. These findings contribute to a better understanding of the immune response and potential prognostic markers in patients with lung sequelae after COVID-19.

Blood-Type-A is a COVID-19 infection and hospitalization risk in a Turkish cohort

We have shown in an ethnically homogenous Turkey cohort with more than six thousand cases and 25 thousand controls that ABO blood types that contain anti-A antibody (O and B) are protective against COVID-19 infection and hospitalization, whereas those without the anti-A antibody (A and AB) are risks. The A + AB frequency increases from 54.7 % in uninfected controls to 57.6 % in COVID-19 outpatients, and to 62.5 % in COVID-19 inpatients. The odds-ratio (OR) for lacking of anti-A antibody risk for infection is 1.16 (95 % confidence interval (CI) 1.1-1.22, and Fisher test p-value 1.8 × 10^-7). The OR for hospitalization is 1.23 (95 %CI 1.06-1.42, Fisher test p-value 0.005). A linear regression treating controls, outpatients, inpatients as three numerical levels over anti-A antibody leads to a p-value of 5.9 × 10^-9. All these associations remain to be statistically significant after conditioning over age, even though age itself is a risk for both infection and hospitalization. We also attempted to correct the potential effect from vaccination, even though vaccination information is not available, by using the date of the data collection as a surrogate to vaccination status. Although no significant association between infection/hospitalization with Rhesus blood system was found, forest plots are used to illustrate possible trends.

In-silico study of influence of HLA heterogeneity on CTL responses across ethnicities to SARS-CoV-2

Differences in outcome to COVID-19 infection in different individuals is largely attributed to genetic heterogeneity leading to differential immune responses across individuals and populations. HLA is one such genetic factor that varies across individuals leading to differences in how T-cell responses are triggered against SARS-CoV-2, directly influencing disease susceptibility. HLA alleles that influence COVID-19 outcome, by virtue of epitope binding and presentation, have been identified in cohorts worldwide. However, the heterogeneity in HLA distribution across ethnic groups limits the generality of such association. In this study, we address this limitation by comparing the recognition of CTL epitopes across HLA genotypes and ethnic groups. Using HLA allele frequency data for ethnic groups from Allele Frequency Net Database (AFND), we construct synthetic populations for each ethnic group and show that CTL epitope strength varies across HLA genotypes and populations. We also observe that HLA genotypes, in certain cases, can have high CTL epitope strengths in the absence of top-responsive HLA alleles. Finally, we show that the theoretical estimate of responsiveness and hence protection offered by a HLA allele is bound to vary across ethnic groups, due to the influence of other HLA alleles within the HLA genotype on CTL epitope recognition. This emphasizes the need for studying HLA-disease associations at the genotype level rather than at a single allele level.