Disrupted Toll-Like Receptor Signalling Of Intestinal Epithelium In Intestinal Graft-Versus-Host Disease

The intestine is preferentially damaged in acute graft-versus-graft disease (aGVHD). Patients with intestinal GVHD are usually associated with drug-resistant diarrhea and microflora disturbance. Recent studies suggest that toll-like receptor (TLR) signaling can protect the intestinal epithelial barrier and confer commensal tolerance in health. But less is known about how functional versus dysfunctional TLR pathway opposes or favours the intestinal GVHD.

In the current study, BALB/c mice were transplanted whole spleen and T cell deleted (TCD) bone marrow cells from C57BL/6 mice as GVHD group, and transplanted TCD bone marrow cells as control group. The jejunum, ileum, colon and rectum epithelium were harvested and total RNA of the intestinal epithelium were extracted in two groups. The mRNA expression of classical TLR pathway TLRx/MYD88/IRAK4 signaling molecules (TLR2, TLR4, MYD88, IRAK4 and Tollip) and cytokines (IFN-γ, TNF-α and TGF-β) were detected by RT-PCR.

The intestine of aGVHD recipients showed severe mucosal edema and erythema with histologic changes of apoptotic epithelial cells and crypt cell dropout, while the intestine of recipients in the control group did not show any intestinal GVHD evidence. TLR2 expression was markedly down-regulated and little TLR4 expression was observed in GVHD intestinal epithelium in comparison to control group. MYD88 and IRAK4 expression were lower in the entire intestinal epithelium of GVHD group but only significant in colon and rectum epithelium between the two groups. Tollip, a TLR signaling inhibitor by interfering IRAK, was found much higher in the GVHD group. For cytokines, both of IFN-γ and TNF-α expression were markedly up-regulated from proximal to distal intestine in GVHD group as compared to control group. There was no difference in TGF-β expression between the two groups.

We propose TLR signaling in the intestinal epithelium, especially in colon and rectum, presents disruption in intestinal graft-versus-host disease. IFN-γ and TNF-α might contribute to accelerate TLR pathway alteration.

Liu:It was supported by 863 Program (No. 2011AA020105) and National Public Health Grand Research Foundation ( No. 201202017).: Research Funding; National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China (11A72121174).: Research Funding. Wu:It was supported by 863 Program (No. 2011AA020105) and National Public Health Grand Research Foundation ( No. 201202017).: Research Funding; National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China (11A72121174).: Research Funding. Zhao:863 Program (No. 2011AA020105) and National Public Health Grand Research Foundation ( No. 201202017).: Research Funding; National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China (11A72121174).: Research Funding. Wu:863 Program (No. 2011AA020105) and National Public Health Grand Research Foundation ( No. 201202017): Research Funding; National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China (11A72121174): Research Funding. Zhang:863 Program (No. 2011AA020105) and National Public Health Grand Research Foundation ( No. 201202017): Research Funding; National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China (11A72121174): Research Funding. Fan:863 Program (No. 2011AA020105) and National Public Health Grand Research Foundation ( No. 201202017): Research Funding; National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China (11A72121174): Research Funding. Fan:863 Program (No. 2011AA020105) and National Public Health Grand Research Foundation ( No. 201202017): Research Funding; National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China (11A72121174): Research Funding. Yin:863 Program (No. 2011AA020105) and National Public Health Grand Research Foundation ( No. 201202017): Research Funding; National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China (11A72121174): Research Funding. Zheng:863 Program (No. 2011AA020105) and National Public Health Grand Research Foundation ( No. 201202017): Research Funding; National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China (11A72121174): Research Funding. Yi:863 Program (No. 2011AA020105) and National Public Health Grand Research Foundation ( No. 201202017): Research Funding; National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China (11A72121174): Research Funding. Liu:863 Program (No. 2011AA020105) and National Public Health Grand Research Foundation ( No. 201202017): Research Funding; National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China (11A72121174): Research Funding.