Honokiol Prevents Intestinal Barrier Dysfunction in Mice with Severe Acute Pancreatitis and Inhibits JAK/STAT1 Pathway and Acetylation of HMGB1

Objective: To investigate the effect of honokiol (HON) and the role of high-mobility group protein B1 (HMGB1) on the pathogenesis of severe acute pancreatitis (SAP).

Methods: Thirty mice were numbered according to weight, and randomly divided into 5 groups using a random number table, including control, SAP, SAP and normal saline (SAP+NS), SAP and ethyl pyruvate (SAP+EP), or SAP+HON groups, 6 mice in each group. Samples of pancreas, intestine, and blood were collected 12 h after SAP model induction for examination of pathologic changes, immune function alterations by enzyme linked immunosorbent assay (ELISA), and Western blot. In vitro experiments, macrophages were divided into 5 groups, the control, lipopolysaccharide (LPS), LPS+DMSO (DMSO), LPS+anti-HMGB1 monoclonal antibody (mAb), and LPS+ HON groups. The tight connection level was determined by transmission electron microscopy and fluorescein isothiocyanate-labeled. The location and acetylation of HMGB1 were measured by Western blot. Finally, pyridone 6 and silencing signal transducer and activator of the transcription 1 (siSTAT1) combined with honokiol were added to determine whether the Janus kinase (JAK)/ STAT1 participated in the regulation of honokiol on HMGB1. The protein expression levels of HMGB1, JAK, and STAT1 were detected using Western blot.

Results: Mice with SAP had inflammatory injury in the pancreas, bleeding of intestinal tissues, and cells with disrupted histology. Mice in the SAP+HON group had significantly fewer pathological changes. Mice with SAP also had significant increases in the serum levels of amylase, lipase, HMGB1, tumor necrosis factor- α, interleukin-6, diamine oxidase, endotoxin-1, and procalcitonin. Mice in the SAP+HON group did not show these abnormalities (P<0.01). Studies of Caco-2 cells indicated that LPS increased the levels of occludin and claudin-1 as well as tight junction permeability, decreased the levels of junctional adhesion molecule C, and elevated intercellular permeability (P<0.01). HON treatment blocked these effects. Studies of macrophages indicated that LPS led to low nuclear levels of HMGB1, however, HON treatment increased the nuclear level of HMGB1 (P<0.01). HON treatment also inhibited the expressions of JAK1, JAK2, and STAT1 (P<0.01) and increased the acetylation of HMGB1 (P<0.05).

Conclusion: HON prevented intestinal barrier dysfunction in SAP by inhibiting HMGB1 acetylation and JAK/STAT1 pathway.