Immunomodulatory Effects of Colistin on Macrophages in Rats by Activating the p38/MAPK Pathway

Abstract

Objectives: Colistin has been identified in a Caenorhabditis elegans chemical screening as an immunostimulatory agent that activates the conserved p38/PMK-1 pathway and provides protection against pathogens. Here we aimed to extend those findings to a mammalian model and evaluate the immunomodulatory effects of colistin on rat macrophages. Methods: Macrophages were isolated from Sprague-Dawley (SD) rat. The effects of colistin on the cytokine secretion, phagocytic activity and protein expression were determined by enzyme-linked immunosorbent assay (ELISA), flow cytometry, and Western blotting analysis, respectively. The relative microRNA expression was determined by microarray, and Kyoto Encylopedia of Genes and Genomes (KEGG) was used to identify potential signaling pathways. Results: Our data showed that 5, 10, and 20 µg/ml colistin significantly increased the secretion of TNF-α, while 20 and 5 µg/ml colistin significantly increased the levels of IL-1β and IL-6, respectively. Flow cytometry results showed that the relative mean fluorescence intensity and percentage of phagocytosis in colistin treatment groups were significantly higher compared with the control group, while the increased phagocytosis phenomenon can be blocked by p38 inhibitor. The phagocytic ability of macrophages against Staphylococcus aureus was significantly increased after colistin treatment. Microarray and KEGG pathway analyses revealed that mitogen-activated protein kinase (MAPK), mammalian target of rapamycin (mTOR), chemokine, and B cell receptor were the main pathways involved in the colistin stimulation process. Western blotting analysis demonstrated that the phosphorylated p38 protein level of colistin treatment groups was increased in a dose dependent manner. Conclusions: Present study is the first to demonstrate that colistin had immunomodulatory effects on macrophages in mammals, and the p38/MAPK pathway was involved in such colistin-induced immunomodulatory effect.

Immunomodulatory Effect of Colistin and its Protective Role in Rats with Methicillin-Resistant Staphylococcus aureus-induced Pneumonia

“…At 12 h after the second dosage of colistin, the WBC counts and differential counts were similar compared with the control group. These results were consistent with our previous in vitro studies that 6 h colistin treatment significantly increases the secretion of TNF-α, IL-1β and IL-6 in macrophages from healthy rats (Wang et al, 2019).…”

“…The increased phagocytosis can be blocked by p38 inhibitor SB203580 (Wang et al, 2019). Microarray analyses have revealed that except for mitogen-activated protein kinase (MAPK), mammalian target of rapamycin (mTOR), chemokine and B cell receptor pathways are also greatly impacted during colistin stimulation process (Wang et al, 2019). However, we did not find that SB203580 could fully block the reduction of cytokines in plasma and lung tissues and aggravation of lung injuries caused by colistin.…”

“…Next, it is found in the study of mammalian macrophages that colistin significantly increases the secretion of pro-inflammatory cytokines and phagocytotic ability. The increased phagocytosis can be blocked by p38 inhibitor SB203580 (Wang et al, 2019). Microarray analyses have revealed that except for mitogen-activated protein kinase (MAPK), mammalian target of rapamycin (mTOR), chemokine and B cell receptor pathways are also greatly impacted during colistin stimulation process (Wang et al, 2019).…”

“…Further research demonstrates that colistin increases the secretion of cytokines and phagocytotic ability of macrophages from rats. Furthermore, p38/MAPK pathway is also involved in such colistin-induced immunomodulatory effect (Wang et al, 2019). However, the immunoregulatory effect of colistin in living mammals has not been reported.…”

Review of the Efficacy and Mechanisms of Traditional Chinese Medicines as a Therapeutic Option for Ionizing Radiation Induced Damage

“…Enhancement of the MAPK signal upregulates telomerase activity, initiates changes in chromatin distribution, and regulates the cell cycle ( Shain et al, 2018 ). Activated p38 and JNK signaling pathways are involved in immune regulation ( Wang et al, 2019a ). After p38 activation, a mitochondrial apoptotic pathway is initiated ( Choi et al, 2006 ; Niaudet et al, 2017 ).…”