The role of cholesterol metabolism in predicting clinical outcome of patients with severe COVID-19

Transcriptomic analysis conducted by us previously revealed upregulation of genes involved in low-density lipoprotein particle receptor (LDLR) activity pathway in lethal COVID-19. Last data suggested the possible role of extracellular vesicles and exomeres in COVID-19 pathogenesis. The aim of the present study was to retrospectively evaluate parameters of cholesterol metabolism as possible predictors of fatal outcome of COVID-19. Blood from 39 patients with severe COVID-19 (the main cohort) were collected at the time of admission to the intensive care unit (ICU) (T1) and 7 days after admission to the ICU (T2). After 30 days patients were divided into two subgroups according to outcome-21 non-survivors and 18 survivors. 28 patients (13 non-survivors and 15 survivors) with severe COVID-19 were included as the replication cohort. The study demonstrated that plasma low-and high-density lipoprotein cholesterol levels (LDL-C and HDL-C) were decreased and CCL20/MIP3[a], IL-10, IL-15, IL-27 concentrations were increased in non-survivors compared to controls in T1. STAB1 gene expression was higher in non-survivors than in survivors (p=0.017) in T2. The conjoint fraction of exomeres and LDL particles measured by dynamic light scattering (DLS) was decreased in non-survivors com-pared to survivors in both the main and replication cohorts. We first showed that change of exomeres fraction may be critical in fatal outcome of COVID-19.

Altered level of plasma exosomes in patients with Gaucher disease.

Mutations in the glucocerebrosidase gene (GBA) cause Gaucher disease (GD), the lysosomal storage disorder (LSD), and are the most common genetic risk factor of Parkinson's disease (PD). Lysosome functionality plays a critical role for secretion of extracellular vesicles (EVs) and their content. Here we compared EVs from the blood plasma of 8 GD patients and 8 controls in terms of amounts, size distribution, and composition of their protein cargo. EVs were isolated via sequential centrifugation and characterized by сryo-electron microscopy (cryo-EM), nanoparticle tracking analysis (NTA), and dynamic light scattering (DLS). The presence of exosomal markers HSP70 and tetrasponins were analyzed by Western blot and flow cytometry. Protein profiling was performed by mass-spectrometry (shotgun analysis). Here, for the first time we reported an increased size and altered morphology in exosomes derived from blood plasma of GD patients. An increased size of plasma exosomes from GD patients compared to controls was demonstrated by cryo-EM and DLS (р<0.0001, p < 0.001, respectively) and confirmed by mode size detected by NTA (p < 0.02). Cryo-EM demonstrated an increased number of double and multilayer vesicles in plasma EVs from GD patients. We found that the EVs were enriched with the surface exosomal markers (CD9, СD63, CD81) and an exosome-associated protein HSP70 in case of the patients with the disease. Proteomic profiling of exosomal proteins did not reveal any proteins associated with PD pathogenesis. Thus, we showed that lysosomal dysfunction in GD patients lead to a striking alteration of plasma exosomes in size and morphology.