Non‐invasive imaging of allogeneic transplanted skin graft by ¹³¹I‐anti‐TLR5 mAb

Abstract

Although 18F-fluorodeoxyglucose (18F-FDG) uptake can be used for the non-invasive detection and monitoring of allograft rejection by activated leucocytes, this non-specific accumulation is easily impaired by immunosuppressants. Our aim was to evaluate a 131I-radiolabelled anti-Toll-like receptor 5 (TLR5) mAb for non-invasive in vivo graft visualization and quantification in allogeneic transplantation mice model, compared with the non-specific radiotracer 18F-FDG under using of immunosuppressant. Labelling, binding, and stability studies were performed. BALB/c mice transplanted with C57BL/6 skin grafts, with or without rapamycin treatment (named as allo-treated group or allo-rejection group), were injected with 131I-anti-TLR5 mAb, 18F-FDG, or mouse isotype 131I-IgG, respectively. Whole-body phosphor-autoradiography and ex vivo biodistribution studies were obtained. Whole-body phosphor-autoradiography showed 131I-anti-TLR5 mAb uptake into organs that were well perfused with blood at 1 hr and showed clear graft images from 12 hrs onwards. The 131I-anti-TLR5 mAb had significantly higher graft uptake and target-to-non-target ratio in the allo-treated group, as determined by semi-quantification of phosphor-autoradiography images; these results were consistent with ex vivo biodistribution studies. However, high 18F-FDG uptake was not observed in the allo-treated group. The highest allograft-skin-to-native-skin ratio (A:N) of 131I-anti-TLR5 mAb uptake was significantly higher than the ratio for 18F-FDG (7.68 versus 1.16, respectively). 131I-anti-TLR5 mAb uptake in the grafts significantly correlated with TLR5 expression in the allograft area. The accumulation of 131I-IgG was comparable in both groups. We conclude that radiolabelled anti-TLR5 mAb is capable of detecting allograft with high target specificity after treatment with the immunosuppressive drug rapamycin.

Anti-migratory effect of rapamycin impairs allograft imaging by 18F-fluorodeoxyglucose-labeled splenocytes

“…Histological analysis was performed and confirmed reduced FR cell accumulation in allografts. The present study employs molecular imaging to extend the results of a previous study in which 18 F-FDG was determined to be unsuitable as a rapamycin-treated graft biotracer (11). In the present study, the accumulation of FR cells in the allograft was barely visible when compared with FC cells.…”

“…The aim of administering immunosuppressants is to impair the metabolic activity of effector cells, which results in decreased 18 F-FDG uptake. This was demonstrated in our previous research, which revealed that the immunosuppressant rapamycin significantly reduced 18 F-FDG uptake and prevented imaging of the graft (11). As an inhibitor of the intracellular kinase, mammalian target of rapamycin (mTOR), rapamycin is an immunosuppressive agent commonly administered to transplant recipients.…”

TLR5 is a new reporter for triple‐negative breast cancer indicated by radioimmunoimaging and fluorescent staining

“…Recently, it was reported that TLR5 was associated with tumour growth and metastasis, 27 and TLR5 expression was positively related with allo-transplant rejection in our previously study. 24 Considering of TLR5 expressed on NK cells within breast cancer reported by other research 28 and TLR5 expression is able to restrain tumour growth and metastasis both in vitro and in vivo, 29 we postulated that TLR5 on TNBC cells may play an important role in TNBC progression, which may be a new target suitable for diagnosis and targeted therapy for TNBC.…”

“…Our laboratory has successfully prepared iodine 131 labelled anti-TLR5 antibody and it could be used to indicate allotransplantation rejection. 24 However, whether it could be used as a non-invasive monitoring target for TNBC is not fully understood. Here, we constructed a TLR5 gene knock-down TNBC cell line 4T1 with lentivirus-shRNA knock-down virus transfection and prepared TLR5 targeting radioisotope labelled probe, to investigate whether TLR5 could be a new target for TNBC non-invasive monitoring in vivo and underlying mechanisms.…”

“…However, these target molecules still exist some deficiency, such as low selection and low molecular expression on tumour. Our laboratory has successfully prepared iodine 131 labelled anti‐TLR5 antibody and it could be used to indicate allotransplantation rejection . However, whether it could be used as a non‐invasive monitoring target for TNBC is not fully understood.…”