Date Published: August 19, 2019
Publisher: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia
Author(s): Yezhou Shen, Jiaoyang Yu, Yunyan Jing, Jian Zhang.
To investigate the role and related mechanisms of miR-106a in sepsis-induced AKI.
Serum from sepsis and healthy patients was collected, sepsis mouse model was established by cecal ligation and puncture (CLP). TCMK-1 cells were treated with lipopolysaccharide (LPS) and transfected with THBS2-small interfering RNA (siTHBS2), miR-106a inhibitor, miR-106a mimics and their negative controls (NCs). The expression of miR-106a, thrombospondin 2 (THBS2), Bax, cleaved caspase-3 and Bcl-2, cell viability, relative caspase-3 activity and TNF-α, IL-1β, IL-6 content were respectively detected by quantitative real-time polymerase chain reaction (qRT-PCR), western blotting, Cell Counting Kit-8 (CCK-8) and enzyme linked immunosorbent assay (ELISA). The relationship between miR-106a and THBS2 was confirmed by dual luciferase reporter assay.
MiR-106a was up-regulated in serum of sepsis patients, CLP-induced mice models and LPS-induced TCMK-1 cells. LPS reduced cell viability and Bcl-2 expression, and increased caspase-3 activity, Bax expression, the content of TNF-α, IL-1β, IL-6. THBS2 was a target of miR-106a. The decreases of caspase-3 activity, TNF-α, IL-1β, IL-6, Bax expression and the increases of cell viability, Bcl-2 expression caused by miR-106a knockdown were reversed when THBS2 silencing in LPS-stimulated TCMK-1 cells.
MiR-106a aggravated LPS-induced inflammation and apoptosis of TCMK-1 cells via regulating THBS2 expression.
Sepsis is a systemic inflammatory response syndrome caused by infection or highly suspicious infection, and is also a major cause of multiple organ failure and septic shock until death1,2. The uncontrolled inflammatory response and immune dysfunction of the body are the main pathophysiological basis of sepsis2. The degree of excessive inflammation and immune dysfunction directly affect the occurrence and development of sepsis2. Moreover, acute kidney injury (AKI) is one of the most common organ failure symptoms in sepsis3. The pathways of AKI induced by sepsis may include coagulopathy, inflammation, oxidative stress and changes in renal tubular epithelial cells to injury4. However, the mechanism of these effects is complex and there is no clear research report at present.
Between March, 2018 and January, 2019, a total of 50 patients (34 males and 16 females, mean age: 48±7.21 years) with sepsis who lived in Intensive Care Unit (ICU) and 30 healthy controls (21 males and 9 females, mean age: 42±5.46 years) were recruited in this study from The Affiliated Hospital of Hangzhou Normal University. The diagnosis of sepsis complied with the American College of Chest Physicians (ACCP) and the Society of Critical Care Medicine (SCCM) joint definition of sepsis diagnostic criteria in US17.
Sepsis is a disordered state in which an inflammatory response is out of control due to severe infection3. In recent years, it has been found that miRNAs can regulate the imbalanced inflammatory response by down-regulating inflammatory factors at the post-transcriptional level, suggesting that miRNAs play a very important role in inflammatory response and immune regulation of sepsis5. The latest findings confirm that the expression of miRNAs in serum of sepsis patients is also different from that of healthy people6,7,20,21. Vasilescu et al.20 used microarray detection technology to compare the differences in miRNA expression profiles in sepsis patients with normal human serum, and then the results showed that the expressions of miR-150, miR-182 and miR-486 were significantly different in patients with sepsis. Wang et al.21 reported that miR-146a and miR-233 expressions were reduced in serum of patients with sepsis. Moreover, Wu et al.9 displayed that the expression of miR-106a was up-regulated in the serum of sepsis mice and inflammatory bowel disease mice model. However, our results in this study were consistent with Wu’s report, that is, we found that the level of miR-106a was increased in the serum of sepsis patients, CLP-treated mice models and LPS-induced cells. These results suggested that miR-106a might be an ideal indicator for the detection and treatment of sepsis or sepsis-induced AKI. Furthermore, a research showed that the absence of miR-106a could alleviate the inflammatory response10. It has also been reported that miR-106a can inhibit cell proliferation and promote apoptosis in astrocytoma22. Hence, we detected LPS-stimulated TCMK-1 cell viability and apoptosis-related proteins expression, and found that miR-106a knockdown decreased apoptosis and increased cell viability, illustrating that miR-106a could involve in the process of sepsis-induced AKI.