Abstract:

Objective To discuss the promotion effect of chemokine C-C motif ligand 19 （CCL19） induced macrophage M1 polarization on chronic pancreatitis of the mice， and to clarify its related mechanism. Methods Ten male C57BL/6N mice were selected， and the pancreatic acinar cells and peritoneal macrophages were extracted from these mice to construct the macrophage-acinar cell co-culture system. The co-culture system cells were divided into control group， model group， and small interfering RNA CCL19 （si-CCL19） group. The morphology of the acinar cells in various groups were observed under microscope. Forty mice were randomly selected and divided into normal group and chronic pancreatitis group， and there were 20 mice in each group. HE staining was used to observe the pathomorphology of pancreatic tissue of the mice in two groups； immunofluorescence staining was used to observe the expressions of cytokeratin 19 （CK19）， amylase， M1 macrophage-related markers inducible nitric oxide synthase （iNOS）， and F4/80 in pancreatic tissue of the mice in two groups and morphology of follicular cells and the expressions of CK19， amylase in the co-culture system cells in various groups； enzyme-linked immunosorbent assay （ELISA） was used to detect the levels of tumor necrosis factor-α （TNF-α）， interleukin （IL）-6， and IL-1β in serum of the mice in two groups and in the co-culture system cells in various groups； immunohistochemistry was used to observe the expression of CCL19 protein in pancreatic tissue of the mice in two groups； Western blotting method was used to detect the expression levels of CCL19 protein and two nuclear factor-κB （NF-κB） signaling pathway-related proteins P65， phosphorylate P65 （p-P65）， kappa B inhibitor of kinase α/β（IKKα/β）， phosphorylated IKKα/β （p-IKKα/β）， IkBα， phosphorylated IκBα（p-IκBα） in pancreatic tissue of the mice in two groups and in the co-culture system cells in various groups. Results The HE staining results showed that the acinar cells in pancreatic tissue of the mice in normal group were tightly arranged； compared with normal group， the acinar cells of the mice in chronic pancreatitis group showed obvious vacuolation and acinar cell ductal metaplasia， indicating successful preparation of the mouse pancreatitis model. The immunofluorescence staining results showed that compared with control group， the acinar cells in model group exhibited severe vacuolation， the CK19 expression was significantly increased， and the amylase expression was significantly decreased； compared with model group， the acinar cell ductal metaplasia in si-CCL19 group was decreased， the CK19 expression was significantly decreased， and the amylase expression was significantly increased； compared with normal group， the expression of amylase in pancreatic tissue of the mice in chronic pancreatitis group was significantly decreased， while the expressions of CK19 and M1 macrophage markers iNOS and F4/80 were significantly increased. The ELISA results showed that compared with normal group， the serum levels of TNF-α， IL-6， and IL-1β of the mice in chronic pancreatitis group were significantly increased （P<0.05）； compared with control group， the levels of TNF-α， IL-6， and IL-1β in the cells in model group were significantly increased （P<0.05）； compared with model group， the levels of TNF-α， IL-6， and IL-1β in the cells in si-CCL19 group were significantly decreased （P<0.05）. The immunohistochemistry results showed that compared with normal group， the expression of CCL19 protein in pancreatic tissue of the mice in chronic pancreatitis group was significantly increased. The Western blotting results showed that compared with normal group， the expression levels of CCL19 protein and NF-κB signaling pathway-related proteins p-P65， p-IKKα/β， and p-IκBα in pancreatic tissue of the mice in chronic pancreatitis group were significantly increased（P<0.05）； compared with control group， the expression levels of CCL19， p-IKKα/β， p-P65， and p-IκBα proteins in the cells in model group were significantly increased （P<0.05）； compared with model group， the expression levels of CCL19， p-IKKα/β， p-P65， and p-IκBα proteins in the cells in si-CCL19 group were decreased （P<0.05）. Conclusion CCL19 promotes the macrophage M1 polarization through the NF-κB signaling pathway， induces the formation of inflammatory microenvironment， and promotes the occurrence and development of pancreatitis.

Key words: Pancreatitis, C-C motif ligand 19, Macrophages, M1 polarization, Nuclear factor-κB