CXCL4 Contributes to the Pathogenesis of Chronic Liver Allograft Dysfunction

Identification of HO-1 as a novel biomarker for graft acute cellular rejection and prognosis prediction after liver transplantation

Background

Liver transplantation (LT) is the most effective treatment for patients with end-stage liver diseases, but acute rejection is still a major concern. However, the mechanisms underlying rejection remain unclear. Biomarkers are lacking for predicting rejection and long-term survival after LT.

Methods

Isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomics was performed between acute cellular rejection (ACR) and non-rejection recipients. The molecular signature differences and potential biomarkers were identified by comprehensive bioinformatics. Heme oxygenase-1 (HO-1) expression and its association with clinical outcomes were investigated by tissue microarrays consisted of liver specimens from recipients with (n=80) and without ACR (n=57).

Results

A total of 287 differentially expressed proteins (DEPs) were identified. Pathway analysis revealed that T/B cell activation, integrin/inflammation signaling pathway, etc. were significantly correlated with ACR. Through comprehensive bioinformatics, HO-1 was identified as a candidate potential biomarker for ACR. In tissue microarray (TMA) analysis, HO-1 expression was significantly higher in ACR group than in non-rejection group (P<0.01). Preoperative Child-Pugh and Meld scores were significantly higher in recipients with high HO-1 expression (P<0.01). In a mean 5-year follow-up, recipients with high HO-1 expression were associated with a shorter overall survival (P<0.05). Further multivariate analyses indicated that HO-1 could be an independent adverse prognostic factor for post-transplant survival (P=0.005).

Conclusions

A total of 287 DEPs were identified, providing a set of targets for further research. Recipients with high preoperative HO-1 expression were associated with ACR. HO-1 may be used as a potential biomarker for predicting the development of post-transplant allograft ACR and recipient's survival.

Anticonvulsant agent DPP4 inhibitor sitagliptin downregulates CXCR3/RAGE pathway on seizure models

Epilepsy is a common neurological disorder with a complex etiology. Our previous study demonstrated that dipeptidyl peptidase IV (DPP4) may be associated with the pathogenesis of epilepsy. However, whether the DPP4 inhibitor sitagliptin has an anticonvulsant effect and the underlying mechanism remain to be elucidated. In this study, we determined that sitagliptin remarkably attenuated the severity of seizures in a pentylenetetrazole (PTZ)-induced rat model. In addition, sitagliptin decreased epileptiform activity measured by electroencephalography (EEG) recordings and patch-clamp methods. Interestingly, sitagliptin pretreatment downregulated the RAGE-JAK2/STAT3 pathway and decreased the expression of CXCL4 and CXCR3. Moreover, CXCR3 knockdown decreased the expression of RAGE, JAK2 and STAT3 in cultured neurons, which suggests that CXCR3 is upstream of the RAGE-JAK2/STAT3 pathway. Altogether, our present data suggest that sitagliptin has an anticonvulsant effect, which might act via downregulation of the CXCL4/CXCR3 axis, followed by a decrease in RAGE and JAK2/STAT3 expression. Considering these effects, sitagliptin could be considered as a novel potential anticonvulsant drug.