miR-486-5p predicted adverse outcomes of SCAP and regulated K. pneumonia infection via FOXO1

Abstract

Purpose: Severe community-acquired pneumonia (SCAP) is a common respiratory system disease with rapid development and high mortality. Exploring effective biomarkers for early detection and development prediction of SCAP is of urgent need. The function of miR-486-5p in SCAP diagnosis and prognosis was evaluated to identify a promising biomarker for SCAP.

Patients and methods: The serum miR-486-5p in 83 patients with SCAP, 52 healthy individuals, and 68 patients with mild CAP (MCAP) patients were analyzed by PCR. ROC analysis estimated miR-486-5p in screening SCAP, and the Kaplan-Meier and Cox regression analyses evaluated the predictive value of miR-486-5p. The risk factors for MCAP patients developing SCAP were assessed by logistic analysis. The alveolar epithelial cell was treated with Klebsiella pneumonia to mimic the occurrence of SCAP. The targeting mechanism underlying miR-486-5p was evaluated by luciferase reporter assay.

Results: Upregulated serum miR-486-5p screened SCAP from healthy individuals and MCAP patients with high sensitivity and specificity. Increasing serum miR-486-5p predicted the poor outcomes of SCAP and served as a risk factor for MCAP developing into SCAP. K. pneumonia induced suppressed proliferation, significant inflammation and oxidative stress in alveolar epithelial cells, and silencing miR-486-5p attenuated it. miR-486-5p negatively regulated FOXO1, and the knockdown of FOXO1 reversed the effect of miR-486-5p in K. pneumonia-treated alveolar epithelial cells.

Conclusion: miR-486-5p acted as a biomarker for the screening and monitoring of SCAP and predicting the malignancy of MCAP. Silencing miR-486-5p alleviated inflammation and oxidative stress induced by K. pneumonia via negatively modulating FOXO1.

Keywords: Diagnosis; Inflammatory response; Malignancy; Oxidative stress; Prognosis; Severity.

Fig. 1

a-c. Increasing serum miR-486-5p was observed in patients with SCAP (a), which discriminate SCAP relative to healthy individuals (b) and patients with MCAP (c). d-f. miR-486-5p was positively correlated with LAC (r = 0.682, d), PCT (r = 0.769, e), and PSI (r = 0.741, f). ^*P < 0.05, ^***P < 0.001, ^****P < 0.0001

Fig. 2

The higher miR-486-5p level was related with adverse prognosis of patients with SCAP (a) and served as an adverse prognostic indicator (b). The dash line in Kaplan-Meier curve indicates 95% CI

Fig. 3

Higher miR-486-5p was correlated with the development of MCAP to SCAP (a). The dash line in Kaplan-Meier curve indicates 95% CI. miR-486-5p in MCAP was upregulated after developing to SCAP (b) and was identified as a risk factor for MCAP developing to SCAP (c)

Fig. 4

The direct target genes of miR-486-5p were predicted from TargetScan, ECORI, miRDB, and miRWalk databases (a). K. pneumonia induced increasing miR-486-5p (b) and decreasing FOXO1 (c) in ACEII cells. miR-486-5p could negatively regulate the expression (c) and luciferase activity (d) of FOXO1 in K. pneumonia-treated ACEII cells. ^nsP > 0.05, ^*P < 0.05, ^**P < 0.01, ^***P < 0.001, ^****P < 0.0001

Fig. 5

K. pneumonia suppressed proliferation (a) and enhanced TNF-alpha (b), IL-6 (c), and IL-1beta (d) levels, which was alleviated by miR-486-5p knockdown. Silencing FOXO1 could reverse the attenuated effect of miR-486-5p on K. pneumonia-treated ACEII cells. ^*P < 0.05, ^**P < 0.01, ^***P < 0.001

Fig. 6

K. pneumonia induced the increasing levels of ROS (a) and MDA (b) and decreasing levels of GSH (c) and SOD (d), indicating significant oxidative stress. Silencing miR-486-5p could alleviate the oxidative stress, which was reversed by the FOXO1 knockdown. ^*P < 0.05, ^**P < 0.01, ^***P < 0.001