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A high accuracy method of angular vibration measurement based on a retroreflection film He-Ne laser interferometer and rotary encoder is proposed for the angular vibration calibration. The retroreflection film interferometer is applied at higher frequencies for smaller angle vibration measurement, while the rotary encoder is used at lower frequencies for wider angle vibration measurement. The measurement principle of the retroreflection film interferometer and the rotary encoder are theoretically analysed according to the different vibration frequencies and different vibration angles, and the experimental results from the proposed method have a good consistence with that from the traditional diffraction grating interferometer method in the primary angular vibration calibration. The proposed method presents several advantages in comparison to the diffraction grating interferometer method, including the lower frequency range, the much lower cost, the convenience and flexibility of the use. [ABSTRACT FROM AUTHOR]

Objective: To explore the effect and underlying mechanism of increased expression of M-type phospholipase A 2 receptor (PLA 2 R) on podocyte membrane induced by hepatitis B virus X protein (HBx) on podocyte pyroptosis in hepatitis B virus-associated glomerulonephritis (HBV-GN). Methods: Transfection of the HBx gene into human kidney podocytes was used to mimic the HBV-GN pathogenesis process. Subsequently, podocytes were divided into the following eight groups: normal control plus secretory phospholipase A 2 -ⅠB (sPLA 2 -ⅠB) group, empty plasmid plus sPLA 2 -ⅠB group, HBx group, HBx plus sPLA 2 -ⅠB group, HBx plus sPLA 2 -ⅠB plus PLA 2 R control siRNA group, HBx plus sPLA 2 -ⅠB plus PLA 2 R-siRNA group, HBx plus sPLA 2 -ⅠB plus ROS control siRNA group, and HBx plus sPLA 2 -ⅠB plus ROS-siRNA group. Podocyte morphology was observed under a transmission electron microscope, and PLA 2 R expression was detected under a fluorescence microscope. Podocyte pyroptosis and reactive oxygen species (ROS) expression were analyzed by flow cytometry, and the mRNA and protein expression of PLA 2 R, nucleotide-binding oligomerization domain-like receptor 3 (NLRP3), apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), caspase-1, interleukin (IL)-1β and IL-18 were determined by real-time fluorescence quantitative PCR and Western blot. Results: Compared with the control group, the expression of PLA 2 R on podocyte membrane significantly increased after transfection with HBx plasmid in vitro (4.07±0.41 vs 1.01±0.17, P <0.001). Transmission electron microscope and fluorochrome-labeled inhibitor of caspases/propidium iodide (FLICA/PI) double staining suggested that overexpressed PLA 2 R combined with sPLA 2 -ⅠB caused aggravated podocyte injury and increased pyroptosis (20.22%±0.36% vs 7.86%±0.28%, P <0.001). Moreover, the expression levels of ROS (4 324 515±222 764 vs 12 920±46, P <0.001), NLRP3 (48.30±2.73 vs 1.00±0.11, P <0.001), ASC (4.02±0.84 vs 1.01±0.15, P <0.001), caspase-1 (3.99±0.42 vs 1.00±0.11, P <0.001), IL-1β (9.08±0.75 vs 1.00±0.09, P <0.001) and IL-18 (19.20±0.70 vs 1.00±0.02, P <0.001) increased when PLA 2 R was overexpressed. In contrast, with the addition of PLA 2 R-siRNA or ROS-siRNA to knockdown the expression of related substances, podocyte injury was alleviated and the degree of pyroptosis decreased, and the expressions of genes related to the downstream signaling pathway (NLRP3, ASC, caspase-1, IL-1β and IL-18) decreased (all P <0.01). Conclusion: HBx may promote podocyte pyroptosis in HBV-GN by targeting the ROS-NLRP3 signaling pathway via the upregulation of PLA 2 R.

Objective: To investigate the potential function and related mechanism of microRNA-223 (miRNA-223) in the podocyte pyroptosis of hepatitis B virus (HBV)-associated glomerulonephritis induced by HBV X protein (HBx). Methods: HBx-overexpressing lentivirus was transfected into human renal podocytes to mimic the pathogenesis of HBV-GN. Real-time fluorescence quantitative PCR and Western blotting experiments were used to detect the mRNA and protein expression of pyroptosis-related proteins [nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3), apoptosis-associated speck-like protein containing a CARD (ASC) and caspase-1], and inflammatory factors (interleukin-1β and interleukin-18), respectively.TUNEL staining and flow cytometry were used to detect the number of pyroptosis cells. Immunofluorescence staining was used to detect the expression of podocytes biomarkers desmin and nephrin; Hoechst 33342 staining was used to observe the morphological and quantitative changes of podocyte nuclei. Enzyme-linked immunosorbent assay was used to measure caspase-1 activity. The dual luciferase reporter gene assay was used to verify the downstream target of miRNA-223. Podocytes were divided into the following nine groups: control group (no special treatment), empty plasmid group (transfected with empty plasmid), HBx overexpression group (transfected with HBx overexpression lentivirus), HBx overexpression+miRNA-223 mimic group (transfected with HBx overexpression lentivirus and miRNA-223 mimic), HBx overexpression+miRNA-223 inhibitor group (transfected with HBx overexpression lentivirus and miRNA-223 inhibitor), HBx overexpression+miRNA-223 mimic+NLRP3 group (transfected with HBx overexpression lentivirus, miRNA-223 mimic and NLRP3 overexpression plasmid), HBx overexpression+miRNA-223 mimic+ NLRP3 siRNA group (transfected with HBx overexpression lentivirus, miRNA-223 mimic and NLRP3 siRNA), HBx overexpression+miRNA-223 inhibitor+NLRP3 group (transfected with HBx overexpression lentivirus, miRNA-223 inhibitor and NLRP3 overexpression plasmid), HBx overexpression+miRNA-223 inhibitor+NLRP3 siRNA group (transfected with HBx overexpression lentivirus, miRNA-223 inhibitor and NLRP3 siRNA). Results: miRNA-223 was down-regulated in HBx overexpression group compared with the control group ( P < 0.05). TUNEL and immunofluorescence staining showed that NLRP3 knockdown attenuated podocyte injury and pyroptosis induced by HBx overexpression ( P < 0.05). Dual luciferase reporter gene assay demonstrated that NLRP3 was one of the downstream targets of miRNA-223. Rescue experiments revealed that NLRP3 overexpression weakened the protective effect of miRNA-223 in podocyte injury ( P < 0.05). The addition of miRNA-223 mimic and NLRP3 siRNA decreased the expression of NLRP3 inflammasome and cytokines, and reduced the number of pyroptosis cells induced by HBx overexpression (all P < 0.05); The addition of miRNA-223 inhibitor and NLRP3 overexpression plasmid significantly increased the expression of NLRP3 inflammasome and cytokines, caspase-1 activity, and the number of pyroptosis cells (all P < 0.05). Conclusion: HBx may promote podocyte pyroptosis of HBV-GN via downregulating miRNA-223 targeting NLRP3 inflammasome, suggesting that miRNA-223 is expected to be a potential target for the treatment of HBV-GN.