Immunofluorescence study of cytoskeleton in endothelial cells induced with malaria sera.

BACKGROUND: Endothelial cells (ECs) play a major role in malaria pathogenesis, as a point of direct contact of parasitized red blood cells to the blood vessel wall. The study of cytoskeleton structures of ECs, whose main functions are to maintain shape and provide strength to the EC membrane is important in determining the severe sequelae of Plasmodium falciparum malaria. The work investigated the cytoskeletal changes (microfilaments-actin, microtubules-tubulin and intermediate filaments-vimentin) in ECs induced by malaria sera (Plasmodium vivax, uncomplicated P. falciparum and complicated P. falciparum), in relation to the levels of pro-inflammatory cytokines. METHODS: Morphology and fluorescence intensity of EC cytoskeleton stimulated with malaria sera were evaluated using immunofluorescence technique. Levels of tumour necrosis factor (TNF) and interferon (IFN)-gamma (γ) were determined using enzyme-linked immunosorbent assay (ELISA). Control experimental groups included ECs incubated with media alone and non-malaria patient sera. Experimental groups consisted of ECs incubated with malaria sera from P. vivax, uncomplicated P. falciparum and complicated P. falciparum. Morphological scores of cytoskeletal alterations and fluorescence intensity were compared across each experiment group, and correlated with TNF and IFN-γ. RESULTS: The four morphological changes of cytoskeleton included (1) shrinkage of cytoskeleton and ECs with cortical condensation, (2) appearance of eccentric nuclei, (3) presence of "spiking pattern" of cytoskeleton and EC membrane, and (4) fragmentation and discontinuity of cytoskeleton and ECs. Significant damages were noted in actin filaments compared to tubulin and vimentin filaments in ECs stimulated with sera from complicated P. falciparum malaria. Morphological damages to cytoskeleton was positively correlated with fluorescence intensity and the levels of TNF and IFN-γ. CONCLUSIONS: ECs stimulated with sera from complicated P. falciparum malaria showed cytoskeletal alterations and increased in fluorescence intensity, which was associated with high levels of TNF and IFN-γ. Cytoskeletal changes of ECs incubated with complicated P. falciparum malaria sera can lead to EC junctional alteration and permeability changes, which is mediated through apoptotic pathway. The findings can serve as a basis to explore measures to strengthen EC cytoskeleton and alleviate severe malaria complications such as pulmonary oedema and cerebral malaria. In addition, immunofluorescence intensity of cytoskeleton could be investigated as potential prognostic indicator for malaria severity.

High Mobility Group Box 1 and Interleukin 6 at Intensive Care Unit Admission as Biomarkers in Critically Ill COVID-19 Patients.

Exuberant inflammation manifesting as a "cytokine storm" has been suggested as a central feature in the pathogenesis of severe coronavirus disease 2019 (COVID-19). This study investigated two prognostic biomarkers, the high mobility group box 1 (HMGB1) and interleukin-6 (IL-6), in patients with severe COVID-19 at the time of admission in the intensive care unit (ICU). Of 60 ICU patients with COVID-19 enrolled and analyzed in this prospective cohort study, 48 patients (80%) were alive at ICU discharge. HMGB1 and IL-6 plasma levels at ICU admission were elevated compared with a healthy control, both in ICU nonsurvivors and ICU survivors. HMGB1 and IL-6 plasma levels were higher in patients with a higher Sequential Organ Failure Assessment (SOFA) score (> 10), and the presence of septic shock or acute kidney injury. HMGB1 and IL-6 plasma levels were also higher in patients with a poor oxygenation status (PaO2/FiO2 < 150 mm Hg) and a longer duration of ventilation (> 7 days). Plasma HMGB1 and IL-6 levels at ICU admission also correlated with other prognostic markers, including the maximum neutrophil/lymphocyte ratio, D-dimer levels, and C-reactive protein levels. Plasma HMGB1 and IL-6 levels at ICU admission predicted ICU mortality with comparable accuracy to the SOFA score and the COVID-GRAM risk score. Higher HMGB1 and IL-6 were not independently associated with ICU mortality after adjustment for age, gender, and comorbidities in multivariate analysis models. In conclusion, plasma HMGB1 and IL6 at ICU admission may serve as prognostic biomarkers in critically ill COVID-19 patients.