Aquaporin-1 inhibition exacerbates ischemia-reperfusion-induced lung injury in mouse

Aquaporin 1 aggravates lipopolysaccharide-induced macrophage polarization and pyroptosis

Acute respiratory infections (ARIs) are associated with high mortality and morbidity. Acute lung injury (ALI) is caused by the activation of immune cells during ARIs caused by viruses such as SARS-CoV-2. Aquaporin 1 (AQP1) is distributed in a variety of immune cells and is related to the occurrence of ALI, but the mechanism is not clear. A reference map of human single cells was used to identify macrophages in COVID-19 patients at the single-cell level. "FindMarkers" was used to analyze differentially expressed genes (DEGs), and "clusterProfiler" was used to analyze the functions of the DEGs. An M1 macrophage polarization model was established with lipopolysaccharide (LPS) in vitro, and the relationships among AQP1, pyroptosis and M1 polarization were examined by using an AQP1 inhibitor. Transcriptome sequencing and RT-qPCR were used to examine the molecular mechanism by which AQP1 regulates macrophage polarization and pyroptosis. Antigen presentation, M1 polarization, migration and phagocytosis are abnormal in SARS-CoV-2-infected macrophages, which is related to the high expression of AQP1. An M1 polarization model of macrophages was constructed in vitro, and an AQP1 inhibitor was used to examine whether AQP1 could promote M1 polarization and pyroptosis in response to LPS. Transcriptome and cell experiments showed that this effect was related to a decrease in chemokines caused by AQP1 deficiency. AQP1 participates in M1 polarization and pyroptosis in macrophages by increasing the levels of chemokines induced by LPS, which provides new insights for the diagnosis and treatment of ALI.

Effects of Radioactive 56MnO2 Particle Inhalation on Mouse Lungs: A Comparison between C57BL and BALB/c

The effects of residual radiation from atomic bombs have been considered to be minimal because of its low levels of external radioactivity. However, studies involving atomic bomb survivors exposed to only residual radiation in Hiroshima and Nagasaki have indicated possible adverse health effects. Thus, we investigated the biological effects of radioactive dust of manganese dioxide 56 (56MnO2), a major radioisotope formed in soil by neutron beams from a bomb. Previously, we investigated C57BL mice exposed to 56MnO2 and found pulmonary gene expression changes despite low radiation doses. In this study, we examined the effects in a radiation-sensitive strain of mice, BALB/c, and compared them with those in C57BL mice. The animals were exposed to 56MnO2 particles at two radioactivity levels and examined 3 and 65 days after exposure. The mRNA expression of pulmonary pathophysiology markers, including Aqp1, Aqp5, and Smad7, and radiation-sensitive genes, including Bax, Phlda3, and Faim3, was determined in the lungs. The radiation doses absorbed in the lungs ranged from 110 to 380 mGy; no significant difference was observed between the two strains. No exposure-related pathological changes were observed in the lungs of any group. However, the mRNA expression of Aqp1 was significantly elevated in C57BL mice but not in BALB/c mice 65 days after exposure, whereas no changes were observed in external γ-rays (2 Gy) in either strain. In contrast, Faim3, a radiation-dependently downregulated gene, was reduced by 56MnO2 exposure in BALB/c mice but not in C57BL mice. These data demonstrate that inhalation exposure to 56MnO2 affected the expression of pulmonary genes at doses <380 mGy, which is comparable to 2 Gy of external γ-irradiation, whereas the responses differed between the two mouse strains.

AQP1 in the Gastrointestinal Tract of Mice: Expression Pattern and Impact of AQP1 Knockout on Colonic Function

Aquaporin 1 (AQP1) is one of thirteen known mammalian aquaporins. Its main function is the transport of water across cell membranes. Lately, a role of AQP has been attributed to other physiological and pathological functions including cell migration and peripheral pain perception. AQP1 has been found in several parts of the enteric nervous system, e.g., in the rat ileum and in the ovine duodenum. Its function in the intestine appears to be multifaceted and is still not completely understood. The aim of the study was to analyze the distribution and localization of AQP1 in the entire intestinal tract of mice. AQP1 expression was correlated with the hypoxic expression profile of the various intestinal segments, intestinal wall thickness and edema, as well as other aspects of colon function including the ability of mice to concentrate stools and their microbiome composition. AQP1 was found in a specific pattern in the serosa, the mucosa, and the enteric nervous system throughout the gastrointestinal tract. The highest amount of AQP1 in the gastrointestinal tract was found in the small intestine. AQP1 expression correlated with the expression profiles of hypoxia-dependent proteins such as HIF-1α and PGK1. Loss of AQP1 through knockout of AQP1 in these mice led to a reduced amount of bacteroidetes and firmicutes but an increased amount of the rest of the phyla, especially deferribacteres, proteobacteria, and verrucomicrobia. Although AQP-KO mice retained gastrointestinal function, distinct changes regarding the anatomy of the intestinal wall including intestinal wall thickness and edema were observed. Loss of AQP1 might interfere with the ability of the mice to concentrate their stool and it is associated with a significantly different composition of the of the bacterial stool microbiome.