Aquaporin Expression and Regulation in Clinical and Experimental Sepsis

Sepsis is an inflammatory disorder caused by the host's dysfunctional response to infection. Septic patients present diverse clinical characteristics, and in the recent years, it has been the main cause of death in intensive care units (ICU). Aquaporins, membrane proteins with a role in water transportation, have been reported to participate in numerous biological processes. Their role in sepsis progression has been studied extensively. This review aims to examine recent literature on aquaporin expression and regulation in clinical sepsis, as well as established experimental models of sepsis. We will present how sepsis affects aquaporin expression at the molecular and protein level. Moreover, we will delve into the importance of aquaporin regulation at transcriptional, post-transcriptional, translational, and post-translational levels in sepsis by presenting data on aquaporin regulation by non-coding RNAs and selected chemical molecules. Finally, we will focus on the importance of aquaporin single-nucleotide polymorphisms in the setting of sepsis.

Expression of Human L-Dopa Decarboxylase (DDC) under Conditions of Oxidative Stress

Oxidative stress is known to influence mRNA levels, translation, and proteolysis. The importance of oxidative stress has been demonstrated in several human diseases, including neurodegenerative disorders. L-Dopa decarboxylase (DDC) is the enzyme that converts L-Dopa to dopamine (DA). In spite of a large number of studies, little is known about the biological significance of the enzyme under physiological and pathological conditions. Here, we investigated the relationship between DDC expression and oxidative stress in human neural and non-neural cells. Oxidative stress was induced by treatment with H2O2. Our data indicated that mRNA and protein expression of DDC was enhanced or remained stable under conditions of ROS induction, despite degradation of total RNA and increased cytotoxicity and apoptosis. Moreover, DDC silencing caused an increase in the H2O2-induced cytotoxicity. The current study suggests that DDC is involved in the mechanisms of oxidative stress.

Prognostic Value of HIF-1α-Induced Genes in Sepsis/Septic Shock

Hypoxia is characterized as one of the main consequences of sepsis, which is recognized as the leading cause of death in intensive care unit (ICU) patients. In this study, we aimed to examine whether the expression levels of genes regulated under hypoxia could be utilized as novel biomarkers for sepsis prognosis in ICU patients. Whole blood expression levels of hypoxia-inducible factor-1α (HIF1A), interferon-stimulated gene 15 (ISG15), hexokinase 2 (HK2), lactate dehydrogenase (LDHA), heme oxygenase-1 (HMOX1), erythropoietin (EPO), and the vascular endothelial growth factor A (VEGFA) were measured on ICU admission in 46 critically ill, initially non-septic patients. The patients were subsequently divided into two groups, based on the development of sepsis and septic shock (n = 25) or lack thereof (n = 21). HMOX1 mRNA expression was increased in patients who developed sepsis/septic shock compared to the non-septic group (p < 0.0001). The ROC curve, multivariate logistic regression, and Kaplan-Meier analysis demonstrated that HMOX1 expression could be utilized for sepsis and septic shock development probability. Overall, our results indicate that HMOX1 mRNA levels have the potential to be a valuable predictive factor for the prognosis of sepsis and septic shock in ICU patients.