TLR-2, TLR-4 and MyD88 genes expression in renal transplant acute and chronic rejections

Graft rejection due to alloreactivity is still the main obstacle to successful renal transplantation. Toll-like receptors (TLRs), which are significantly involved in initiating inflammation, triggering innate immunity, occurrence of ischaemia reperfusion injury (IRI) and subsequent deterioration of allograft function, are of interest in molecular diagnosis of graft rejection.

In present research, we have evaluated the mRNA expressions of TLR-4, TLR-2 and myeloid differentiation primary response gene 88 (MyD88) in peripheral blood mononuclear cells (PBMCs) and biopsy samples of 26 stable graft function (SGF), 14 acute T-cell-mediated rejection (ACMR), six acute antibody-mediated rejection (AAMR), 10 chronic T-cell-mediated rejection (CCMR) and four chronic antibody-mediated rejection (CAMR) cases of renal transplant recipients, using TaqMan detector real-time polymerase chain reaction (RT-PCR).

It was found that TLR4 mRNA level was significantly elevated in PBMCs of both ACMR (P.v: 0.025) and CCMR (P.v: 0.007) cases, while TLR2 gene was upregulated only in PBMCs of ACMR (P.v: 0.024). Moreover, MyD88 expression was increased in biopsy samples of all rejection groups AAMR (P.v: 0.032), ACMR (P.v: 0.002), CAMR (P.v: 0.038) and CCMR (P.v: 0.013) and could distinguish them from stable grafts with AUC (area under curve) of 0.81, 0.80, 0.83 and 0.77, respectively.

These data showed that MyD88 gene upregulation in renal tissue could have diagnostic value and increased level of TLR4 mRNA in PBMCs could be suggestive of cell-mediated rejections. Therefore, monitoring the expression level of inflammatory signalling genes might be useful in predicting allograft rejection.