The 10-kDa chemokine interferon-gamma-inducible protein 10 (IP-10) is considered one of the most promising biomarkers for diagnosing both tuberculosis and COVID-19 infections. The blood samples of patients at different disease states contain different levels of IP-10, which need to be detected in a rapid, specific and ultrasensitive manner. Here, we report a bienzymatic chemiluminescence sandwich immunoassay (BCSI) assay for the ultrasensitive and stable detection of IP-10. In this assay, IP-10 is first efficiently captured using a double-antibody sandwich strategy. The detection antibody is linked to catalase (CAT) via a streptavidin–biotin signal amplification system to achieve highly efficient conversion of hydrogen peroxide (H 2 O 2 ) to oxygen and water. In the chemiluminescence (CL) reaction, horseradish peroxidase (HRP) acts as an efficient catalyst, and 4-bromophenol acts as an enhancer for the cyclic transition of HRP, which results in a strong and durable CL signal. The bienzymatic catalysis with CAT and HRP and the potentiation of 4-bromophenol enables the assay to be ultrasensitive and stable. The CL intensity was found to be well correlated with the detection of IP-10 at levels in the range of 0.71 to 125,000 pg/mL, which covers more than 6 orders of magnitude, with a detection limit of 0.63 pg/mL. The coefficient of variation was 1.49%, and the recovery range of IP-10 in serum was 86.21%-104.57%. This assay provides a wide linear range and high sensitivity and may be a promising method for the high-throughput detection of IP-10 in the diagnosis of tuberculosis and COVID-19.
Li Jiashun,Jie Xiang,Liang Xiaoli,Chen Ziyu,Xie Peifang,Pan Xiping,Zhou Beixian,Li Jing
Background Human respiratory system infected with influenza A virus (IAV) elicited a robust pro-inflammatory response that resulted in severe illness and even death. Currently, limited immunomodulator is available to counteract IAV-associated pneumonia in the clinic. Sinensetin, a polymethoxylated flavone with five methoxy groups, has been found to possess anti-agiogenesis, anti-inflammatory and anti-diabetic activities. However, the effects of sinensetin on IAV-triggered pro-inflammatory response remain unclear. In the present study, the anti-inflammatory effects and corresponding possible mechanism of sinensetin in IAV-infected A549 cells were subjected to investigations. Methods The cytotoxic effects of sinensetin towards A549 cells was detected by MTT and LDH assays. The antiviral activity of sinensetin against influenza A virus was assayed in A549 cells with an engineered replication-competent influenza A virus carrying Gaussia luciferase reporter gene infection. The effect of sinensetin on influenza A virus-triggered inflammatory reaction was determined by qRT-PCR, Luminex assays, ELISA and Western blot. Results Our results showed that sinensetin did not exhibit antiviral activity against A/PR/8/34 (H1N1). Meanwhile, sinensetin treatment significantly decreased IAV-induced expression of pro-inflammatory mediators at mRNA and protein levels, including IL-6, TNF-α, IP-10, IL-8 and MCP-1. Additionally, levels of cyclooxygenase (COX)-2 and the downstream product prostaglandin E 2 (PGE 2 ) up-regulated by IAV infection were dramatically suppressed by sinensetin. The mechanistic investigation revealed that sinensetin treatment suppressed the NF-κB transcriptional activity using the NF-κB reporter stable HEK293 cell line stimulated with TNF-α (20 ng/mL) or influenza H1N1 virus. Furthermore, sinensetin abrogated influenza H1N1 virus-induced activation of NF-κB, ERK1/2 MAPK and p38 MAPK signalings. Conclusion Collectively, our results indicated that sinensetin has potential capacity to attenuate IAV-triggered pro-inflammatory response via inactivation of NF-κB, ERK1/2 MAPK and p38 MAPK signalings, which implied that sinensetin may be a promising candidate drug for influenza H1N1 virus infection therapeutics.
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