Background:

Long-term success of organ transplantation is limited by the inexorable loss of graft function due to rejection. Prevalent dogma defends that allograft rejection is exclusively mediated by the adaptive immune system: T cells are responsible for cellular rejections and B cells producing Donor Specific Antibodies (DSA) are responsible for humoral rejection. Recently, we demonstrated that innate NK cells could be implicated in the generation of chronic vascular rejections lesions by sensing the absence of expression of self Major Histocompatibility Complex (MHC) class I molecules ("missing self") on graft endothelial cells with their Killer cell immunoglobulin-like (KIR) receptors. Using human in vitro and murine in vivo models, we also showed that Mammalian Target Of Rapamycin (mTOR) inhibitors could efficiently prevent this new kind of rejection.

Objective:

The aim of our project is therefore to test in a cohort of kidney transplanted patients the efficiency of mTOR inhibitors to treat this new kind of rejection

Methods:

A cohort of 20 kidney transplant patients with a missing self on their graft responsible for a NK-mediated rejection will be established prospectively. An mTOR inhibitor will be introduced in these patients for 6 months in association with a calcineurin inhibitor and corticosteroids. Graft function, histological lesions and NK activability will be monitored following this modification of treatment.

Inclusion Criteria:

• Patient aged > 18 years
• Kidney transplanted patient
• Having microvascular inflammation lesion on his graft biopsy associated to mild chronic lesions
• In absence of donor specific antibodies
• In presence of a missing self

Exclusion Criteria:

• Proteinuria/urinary creatinin > 100 mg/mmol
• Antecedent of poor tolerance or hypersensibility to everolimus or sirolimus
• Severe chronic lesions
• Presence of donor specific antibodies