The Aquaporin 3 Polymorphism (rs17553719) Is Associated with Sepsis Survival and Correlated with IL-33 Secretion.

Sepsis is a common life-threatening disease caused by dysregulated immune response and metabolic acidosis which lead to organ failure. An abnormal expression of aquaporins plays an important role in organ failure. Additionally, genetic variants in aquaporins impact on the outcome in sepsis. Thus, we investigated the polymorphism (rs17553719) and expression of aquaporin-3 (AQP3) and correlated these measurements with the survival of sepsis patients. Accordingly, we collected blood samples on several days (plus clinical data) from 265 sepsis patients who stayed in different ICUs in Germany. Serum plasma, DNA, and RNA were then separated to detect the promotor genotypes of AQP3 mRNA expression of AQP3 and several cytokines. The results showed that the homozygote CC genotype exhibited a significant decrease in 30-day survival (38.9%) compared to the CT (66.15%) and TT genotypes (76.3%) (p = 0.003). Moreover, AQP3 mRNA expression was significantly higher and nearly doubled in the CC compared to the CT (p = 0.0044) and TT genotypes (p = 0.018) on the day of study inclusion. This was accompanied by an increased IL-33 concentration in the CC genotype (day 0: p = 0.0026 and day 3: p = 0.008). In summary, the C allele of the AQP3 polymorphism (rs17553719) shows an association with increased AQP3 expression and IL-33 concentration accompanied by decreased survival in patients with sepsis.

AQP3 and AQP9-Contrary Players in Sepsis?

Sepsis involves an immunological systemic response to a microbial pathogenic insult, leading to a cascade of interconnected biochemical, cellular, and organ-organ interaction networks. Potential drug targets can depict aquaporins, as they are involved in immunological processes. In immune cells, AQP3 and AQP9 are of special interest. In this study, we tested the hypothesis that these aquaporins are expressed in the blood cells of septic patients and impact sepsis survival. Clinical data, routine laboratory parameters, and blood samples from septic patients were analyzed on day 1 and day 8 after sepsis diagnosis. AQP expression and cytokine serum concentrations were measured. AQP3 mRNA expression increased over the duration of sepsis and was correlated with lymphocyte count. High AQP3 expression was associated with increased survival. In contrast, AQP9 expression was not altered during sepsis and was correlated with neutrophil count, and low levels of AQP9 were associated with increased survival. Furthermore, AQP9 expression was an independent risk factor for sepsis lethality. In conclusion, AQP3 and AQP9 may play contrary roles in the pathophysiology of sepsis, and these results suggest that AQP9 may be a novel drug target in sepsis and, concurrently, a valuable biomarker of the disease.

Cloning and characterization of the GNA11 promoter and its regulation by early growth response 1.

GNAQ and GNA11, encoding the G-proteins Gα(q) and Gα11, are members of the Gα(q)/Gα11 subfamily, which transmits signals from the cell surface to intracellular signalling cascades. The GNAQ promoter was already characterized, and regulation by the transcription factor early growth response 1 (Egr-1) was demonstrated. Interestingly, in silico analysis revealed putative Egr-1 binding sites in sequences potentially representing the GNA11 promoter. However, the GNA11 promoter has not been characterized so far. Therefore, the purpose of the study was the characterization of the GNA11 promoter and investigation of its potential regulation by Egr-1. The putative GNA11 promoter was cloned, and deletion constructs were generated. Luciferase assays were performed, and essential regulatory regions identified between nt-805/-177. In electrophoretic mobility shift assays (EMSAs), one specific Egr-1 binding site at nt-475/-445 was identified. An Egr-1 expression plasmid was generated, which evoked increased Egr-1 content in nuclear extracts and a > 2-fold increase in GNA11 promoter activity in construct nt-805/+54 (p = 0.035). Finally, real-time PCR analysis was performed, and an increased Gα11 mRNA (p = 0.035) expression induced by Egr-1 was found. Here, we characterize for the first time the GNA11 promoter and its specific interaction with Egr-1. Both the GNAQ and the GNA11 promoter appear to be regulated by the same transcription factor, Egr-1, which may be a molecular mechanism leading to Gα(q)-/Gα11-associated phenotypes.