4-Aminoquinoline compounds from the Spanish flu to COVID-19

In 1918, quinine was used as one of the unscientifically based treatments against the H1N1 virus during the Spanish flu pandemic. Originally, quinine was extracted from the bark of Chinchona trees by South American natives of the Amazon forest, and it has been used to treat fever since the seventeenth century. The recent COVID-19 pandemic caused by Sars-Cov-2 infection has forced researchers to search for ways to prevent and treat this disease. Based on the antiviral potential of two 4-aminoquinoline compounds derived from quinine, known as chloroquine (CQ) and hydroxychloroquine (HCQ), clinical investigations for treating COVID-19 are being conducted worldwide. However, there are some discrepancies among the clinical trial outcomes.Thus, even after one hundred years of quinine use during the Spanish flu pandemic, the antiviral properties promoted by 4-aminoquinoline compounds remain unclear. The underlying molecular mechanisms by which CQ and HCQ inhibit viral replication open up the possibility of developing novel analogs of these drugs to combat COVID-19 and other viruses.

Why Septic Patients Remain Sick After Hospital Discharge?

Sepsis is well known to cause a high patient death rate (up to 50%) during the intensive care unit (ICU) stay. In addition, sepsis survival patients also exhibit a very high death rate after hospital discharge compared to patients with any other disease. The addressed question is then: why septic patients remain ill after hospital discharge? The cellular and molecular mechanisms involved in the high rate of septic patient deaths are still unknown. We described herein the studies that investigated the percentage of septic patients that died after hospital discharge ranging from 90 days up to 5 years. We also reported the symptoms of septic patients after hospital discharge and the development of the recently called post-sepsis syndrome (PSS). The most common symptoms of the PSS are cognitive disabilities, physical functioning decline, difficulties in performing routine daily activities, and poor life quality. The PSS also associates with quite often reinfection and re-hospitalization. This condition is the cause of the high rate of death mentioned above. We reported the proportion of patients dying after hospital discharge up to 5 years of followed up and the PSS symptoms associated. The authors also discuss the possible cellular and metabolic reprogramming mechanisms related with the low survival of septic patients and the occurrence of PSS.

The Critical Role of Cell Metabolism for Essential Neutrophil Functions

Neutrophils were traditionally considered as short-lived cells with abundant secretory and protein synthetic activity. Recent studies, however, indicate neutrophils are in reality a heterogeneous population of cells. Neutrophils differentiate from pluripotent stem cells in the bone marrow, and can further mature in the blood stream and can have different phenotypes in health and disease conditions. Neutrophils undergo primary functions such as phagocytosis, production of reactive oxygen species (ROS), release of lipid mediators and inflammatory proteins (mainly cytokines), and apoptosis. Neutrophils stimulate other neutrophils and trigger a cascade of immune and inflammatory responses. The underpinning intracellular metabolisms that support these neutrophil functions are herein reported. It has been known for many decades that neutrophils utilize glucose as a primary fuel and produce lactate as an end product of glycolysis. Neutrophils metabolize glucose through glycolysis and the pentose- phosphate pathway (PPP). Mitochondrial glucose oxidation is very low. The PPP provides the reduced nicotinamide adenine dinucleotide phosphate (NADPH) for the NADPH-oxidase (NOX) complex activity to produce superoxide from oxygen. These cells also utilize glutamine and fatty acids to produce the required adenosine triphosphate (ATP) and precursors for the synthesis of molecules that trigger functional outcomes. Neutrophils obtained from rat intraperitoneal cavity and incubate for 1 hour at 37°C metabolize glutamine at higher rate than that of glucose. Glutamine delays neutrophil apoptosis and maintains optimal NOX activity for superoxide production. Under limited glucose provision, neutrophils move to fatty acid oxidation (FAO) to obtain the required energy for the cell function. FAO is mainly associated with neutrophil differentiation and maturation. Hypoxia, hormonal dysfunction, and physical exercise markedly change neutrophil metabolism. It is now become clear that neutrophil metabolism underlies the heterogeneity of neutrophil phenotypes and should be intense focus of investigation.