3.5 Lysine alleviates PQ-induced inflammatory responses
Lysine was once considered in clinic for preventing or treating cold sores due to herpes simplex with little side effects (Chi, Wang, Delamere, Wojnarowska, Peters & Kanjirath, 2015). Lysine has also been proved to prevent and treat brain trauma and brain ischemia (Kondoh, Kameishi, Mallick, Ono & Torii, 2010). Furthermore, lysine has been believed to be beneficial for the immune response. Considering systemic inflammation is also involved in PQ-raised EMT and pulmonary fibrosis (Dinis-Oliveira, Duarte, Sanchez-Navarro, Remiao, Bastos & Carvalho, 2008), we then analyzed the populations of immune cells in a PQ-poisoned cynomolgus model treated w/wo lysine. Neutrophils and monocytes are two immune populations reflecting PQ poisoning-induced inflammatory responses (Cao et al., 2019; Zhao, Song, Gao, Feng & Li, 2019). Our results show that PQ poisoning increased the number and percentage of neutrophils and monocytes while lysine treatment remarkably reduced such increasement (Fig. 4A&B). In contrast, similar as other reports(Bhardwaj & Saxena, 2014), a reduction of reticulocytes was observed in PQ-poisoned cynomolgus, while lysine treatment even slightly increased the reticulocytes (Fig. 4C). Intriguingly, compared to the vehicle control, we have observed an increase of lymphocytes and WBC in PQ-poisoned cynomolgus treated with lysine (Fig. 4D&E). Considering the C-reactive protein (CRP) was largely reduced in lysine-treated cynomolgus (Fig. 4F), the increased number of WBC and lymphocytes could be the results of nutritional functions by lysine(Bouyeh, 2012) that benefits immune homeostasis. Taken together, these results together indicate that lysine treatment would also maintain immune homeostasis during PQ poisoning.