ABSTRACT
Introduction. In severe cases of coronavirus disease 2019 (COVID-19) pulmonary infiltration is accompanied by cytokine storm syndrome (CSS) development. Besides COVID-19, CSS can be triggered by the range of pathologies, which include hemophagocytic lymphohistiocytosis (sHLH) and septic shock (SS). The aim of this study was to compare immunological profiles in fatal cases of COVID-19, sHLH and SS. Material and methods. Serum levels of IL-1β, IL-2, IL-6, IL-8, IL-10, IL-17A, IL-18, IFN-γ, TNF-α, procalcitonin, neopterin, ferritin with percent of glycosylated fraction (% GF) were measured in 37 COVID-19 fatal cases, collected during 2020 year prospectively;and in 39 sHLH and 47 SS fatal cases, collected within 2018–2019 years retrospectively. Comparison groups also included 194 non-fatal COVID-19 cases and 20 healthy donors, collected during 2020 year. Cytokine concentrations, procalcitonin and neopterin were measured by enzyme-linked immunosorbent assay;the ferritin level was determined by the turbidimetry method. The percent of glycosylated ferritin fraction (% GF) was calculated by the modified method of M. Worwood et al. Results. Deceased patients with COVID-19 had higher IL-6, IL-8, IL-10, IL-18, procalcitonin median levels compared to the survived. Meanwhile IL-8, IL-18, IFN-γ, TNFα and ferritin concentrations were significantly lower in deceased COVID-19 patients compared to sHLH and SS. The levels of IL-6 and procalcitonin in fatal COVID-19 were comparable to SS, but significantly higher than in sHLH. Leucocytes were higher in COVID-19 compared to both SS and sHLH. Conclusion. Each fatal condition was accompanied by specific features of the cytokine profile: high IL-6 combined with low IFN-γ, TNFα in COVID-19;high IL-8, IL-6 with low IL-17A, IL-2 in SS;high IL-18, ferritin, IFN-γ with low IL-6, procalcitonin, % GF in sHLH.
ABSTRACT
The present investigation focuses on the analysis of the interactions among human lactoferrin (LF), SARS-CoV-2 receptor-binding domain (RBD) and human angiotensin-converting enzyme 2 (ACE2) receptor in order to assess possible mutual interactions that could provide a molecular basis of the reported preventative effect of lactoferrin against CoV-2 infection. In particular, kinetic and thermodynamic parameters for the pairwise interactions among the three proteins were measured via two independent techniques, biolayer interferometry and latex nanoparticle-enhanced turbidimetry. The results obtained clearly indicate that LF is able to bind the ACE2 receptor ectodomain with significantly high affinity, whereas no binding to the RBD was observed up to the maximum "physiological" lactoferrin concentration range. Lactoferrin, above 1 µM concentration, thus appears to directly interfere with RBD-ACE2 binding, bringing about a measurable, up to 300-fold increase of the KD value relative to RBD-ACE2 complex formation.