Objective      To investigate the effects of inhibiting inositol requiring 1-X-Box bind

ing protein 1 (IRE1-XBP1) pathway in Kupffer cells (KCs) on liver transplant rejection in rats.   Methods       Orthotopic liver transplantation in rats was established with or without GdCl3 treatment pre-operation. In untreated group

the rats were divided randomly into 3 subgroups

that is

XBP1-shRNA group (A)

Scrambled-shRNA group (B)

and PBS group (C). Likewise

the treated group was sub-divided into GdCl

3

+XBP1-shRNA group (D)

GdCl

3

+Scrambled-shRNA group (E)

and GdCl

3

+PBS group (F). In untreated group

  the serum levels of alanine aminotransferase (ALT)

aspartate aminotransferase (AST)

interferon-γ (IFN-γ)

interleukin-10 (IL-10) and IL-17 were examined at different time points after operation. Liver tissues were excised for hematoxylin and eosin (HE) staining

mRNA expression levels of transcriptional factors (T-bet and RORγt) and cytokines (IFN-γ

IL-17 and IL-10) quantified by real-time PCR (RT-PCR)

and protein levels of CD86

CD206

IFN-γ

IL-17 and IL-10 by Western blotting. Banff schema was used for grading the acute allograft rejection with rejection activity index (RAI). The survival rate was assessed by Kaplan-Meier curve analysis. In the treated group

the mRNA and the protein expression of IFN-γ

IL-17 and IL-10 was also tested. Results     In the untreated group

the serum levels of ALT and AST at different time points were significantly lower in group A compared with groups B and C (P0.05). In group A

IFN-γ and IL-17 were significantly decreased in serum while IL-10 was significantly increased (P0.05). There were consistent with the results of RT-PCR and western blotting. In addition

the relative mRNA expression of T-bet/RORγt was decreased

protein expression of CD86 decreased and CD206 increased

which were all statistically significant (P0.05). In contrast

groups B and C showed inverse trend with respect to the above-mentioned factors

mRNA and protein expressions. Moreover

the differences between group B and C were not significant. The mean RAI sco

re in group A was 3.81±0.14

which was significantly lower than that in groups B (9.13±0.20) and C (8.95±0.26)

respectively (P0.05). The data was also in agreement with the Kaplan-Meier curve

showing that rats in group A significantly survived longer than these in groups B and C (P0.05). However

the expression of IFN-γ

IL-17 and IL-10 both at mRNA and protein levels was not significantly different among the treatment groups D

E

and F. The same results in pathological examination were observed.  Conclusion       The blockage of IRE1-XBP1 pathway could alter the polarization of KCs from M1 to M2 type

lead to skewing of Th1/Th17 towards Th2/Treg

and consequently ameliorate acute rejection following liver transplantation in rats.