Papa-Gobbi Rodrigo, Stringa Pablo, Gentilini Maria Virginia, Ivanoff Ivana, Machuca Mariana, Arreola Nidia Monserrat, Serradilla Javier, Estefanía-Fernández Karla, Talayero Paloma, Velayos María, Sánchez-Zapardiel Elena, Gondolesi Gabriel, Andrés-Moreno Ane, Rumbo Martin, Hernández-Oliveros Francisco
Institute for Immunological and Pathophysiological Studies (IIFP), School of Exact Sciences, National University of La Plata, National Council of Scientific and Technical Research (CONICET), La Plata, Argentina.
Intestinal Failure, Rehabilitation and Transplant Unit, University Hospital Foundation Favaloro; Institute of Translational Medicine, Transplantation and Bioengineering (ImeTTyB), University Favaloro-CONICET, Buenos Aires, Argentina.
PLoS One. 2025 Jan 24;20(1):e0307534. doi: 10.1371/journal.pone.0307534. eCollection 2025.
Intestinal transplantation (ITx) represents the only curative option for patients with irreversible intestinal failure. Nevertheless, its rejection rate surpasses that of other solid organ transplants due to the heightened immunological load of the gut. Regulatory T-cells (Tregs) are key players in the induction and maintenance of peripheral tolerance, suggesting their potential involvement in modulating host vs. graft responses after ITx. Thus, we investigated the association of Tregs with allograft outcomes in pediatric patients and in an experimental model of small bowel transplantation.
Treg frequency in human samples was analyzed by Flow cytometry (CD4+CD25highCD127-, blood samples) and immunohistochemistry (FoxP3, graft samples). Experimental allogenic-heterotopic small bowel transplantation was performed in rats and animals divided into 3 groups: non-immunosuppressant treatment, rapamycin (2 mg/kg), and tacrolimus (0.6 mg/kg) treatment. Acute cellular rejection (ACR) was diagnosed based on clinical and histological findings, graft gene expression of pro- and anti-inflammatory mediators assessed by RT-qPCR, serum IL-6 and IL-10 levels by Luminex, and Treg frequency analyzed by flow cytometry (CD4+CD25highFoxP3+).
Blood samples from patients undergoing ACR exhibited a significant reduction in the Treg number compared to those with normo-functional grafts. Similarly, a diminished number of FoxP3+ cells was observed in mucosa samples with ACR. In the experimental model, rapamycin-treated animals displayed clinical and histological findings resembling those not receiving immunosuppression treatment. Notably, ACR correlated with a high CD8/CD4 ratio, loss of T-cell chimerism, mRNA upregulation of pro-inflammatory genes and diminished graft Treg frequency. In contrast, tacrolimus treatment prevented ACR and facilitate blood and graft Treg expansion. Remarkably, recipients who achieved Treg expansion within the graft remained free of ACR even after discontinuation of the immunosuppressant treatment and this phenomenon was associated with increased levels of serum IL-10.
Our clinical and experimental findings underscore the association between Treg frequency and graft rejection after ITx, advocating for strategies that promote their expansion within the gut mucosa to enhance long-term outcomes.
肠道移植（ITx）是不可逆肠道衰竭患者的唯一治愈选择。然而，由于肠道免疫负荷增加，其排斥率超过其他实体器官移植。调节性T细胞（Tregs）是诱导和维持外周耐受的关键因素，提示它们可能参与调节ITx后宿主与移植物的反应。因此，我们研究了Tregs与小儿患者及小肠移植实验模型中同种异体移植物结局的相关性。
通过流式细胞术（CD4+CD25highCD127-，血液样本）和免疫组织化学（FoxP3，移植物样本）分析人类样本中的Treg频率。在大鼠中进行实验性同种异体异位小肠移植，并将动物分为3组：非免疫抑制治疗组、雷帕霉素（2mg/kg）治疗组和他克莫司（0.6mg/kg）治疗组。根据临床和组织学结果诊断急性细胞排斥反应（ACR），通过RT-qPCR评估移植物促炎和抗炎介质的基因表达，通过Luminex检测血清IL-6和IL-10水平，并通过流式细胞术（CD4+CD25highFoxP3+）分析Treg频率。
与移植功能正常的患者相比，发生ACR的患者血液样本中的Treg数量显著减少。同样，在发生ACR的黏膜样本中观察到FoxP3+细胞数量减少。在实验模型中，雷帕霉素治疗的动物表现出与未接受免疫抑制治疗的动物相似的临床和组织学结果。值得注意的是，ACR与高CD8/CD4比值、T细胞嵌合现象丧失、促炎基因mRNA上调以及移植物Treg频率降低相关。相反，他克莫司治疗可预防ACR并促进血液和移植物Treg扩增。值得注意的是，在移植物内实现Treg扩增的受者即使在停用免疫抑制治疗后仍未发生ACR，且这种现象与血清IL-10水平升高有关。
我们的临床和实验结果强调了Treg频率与ITx后移植物排斥之间的关联，主张采取促进其在肠道黏膜内扩增的策略以改善长期结局。
