Alloantigen-specific T-cell hyporesponsiveness induced by dnIKK2 gene-transfected recipient immature dendritic cells.

Immature dendritic cells (iDCs) have been shown to be able to induce peripheral T-cell tolerance through distinct pathways. Here, we investigated the tolerogenic property of recipient iDCs whose maturation was arrested by a dominant negative mutant of inhibitor of nuclear factor kappa-B kinase 2 (dnIKK2) gene. We found that dnIKK2-iDCs presented a typical semi-mature morphology and expressed lower levels of CD80 and CD86, slightly higher MHC-II than untransfected iDCs. The expression of these molecules had no significant change even dnIKK2-iDCs were pulsed by donor antigen. In primary mixed leukocyte reaction (MLR), dnIKK2-iDCs exhibited impaired ability to stimulate allogeneic T-cells, but induced CD4(+)CD25(-) T-cell formation. In co-culture MLR, these CD4(+)CD25(-) T-cells suppressed T-cell alloreaction in an antigen-specific manner. Besides, CD4(+)CD25(-) T-cells inhibited IL-2 and IFN-γ release, whereas promoted IL-10 and TGF-ß secretion. These data suggested recipient dnIKK2-iDCs could maintain peripheral tolerance through down-regulating costimulatory molecule expressions and inducing CD4(+)CD25(-) T-cell formation.

Prolongation of rat renal allograft survival by CD4⁺CD25⁻ T cells induced by recipient dendritic cells transfected with IKK2dn.

Previous studies have demonstrated that recipient-derived immature dendritic cells transfected by recombinant adenovirus-mediated IKK2dn (Adv­IKK2dn) and loaded with donor splenocyte lysate generate CD4+CD25- T cells (Adv-IKK2dn-CD4+CD25- T cells). These cells may inhibit T cell responses in vitro. In the present study, Lewis (LW) rats were administered with an intravenous injection of naive CD4+ T cells, empty adenovirus (Adv-0)-dendritic cell-generated CD4+CD25- T cells (Adv-0-CD4+CD25- T cells), Adv-IKK2dn-CD4+CD25- T cells or an equal volume of normal saline, seven days prior to transplantation. The potency and the mechanism of action of Adv-IKK2dn-CD4+CD25- T cells was analyzed, as well as an investigation of their tolerogenic properties in vivo. Administration of Adv-IKK2dn-CD4+CD25- T cells in vivo to LW rats was observed to markedly prolong the survival of a kidney allograft from Brown Norway rats. Furthermore, the Adv-IKK2dn-CD4+CD25- T cell-treated group exhibited significantly reduced levels of interleukin (Il)-2 and interferon-γ production and increased Il-10 and transforming growth factor-ß (TGF-ß) secretion. The serum creatinine levels remained at low levels in the Adv-IKK2dn-CD4+CD25- T cell-treated group. Their ability to induce allogeneic T cell proliferation was markedly reduced compared with the other groups. These observations indicated that Adv-IKK2dn-CD4+CD25- T cells induce prolongation of kidney allograft survival in vivo, which is hypothesized to be due to the high expression levels of Il-10 and TGF-ß.

[Expressions of interleukin-15 and osteopontin mRNA in early stage of acute rejection of renal allograft in rats].

OBJECTIVE: To study the expressions of interleukin-15 (IL-15), osteopontin (OPN), granzyme B (GraB) and perforin (PFP) mRNA in early stage of acute rejection (AR) of renal allograft in rats. METHODS: The rat renal transplantation model was established. Male Brown Norway and Lewis rats were used as donors and recipients. Four groups were designated: CsA group (BN-->LEW, n = 10, recipients were treated with CsA i.p.); AB group (BN-->LEW, n = 10, recipients were treated with anti-IL-15 neutralizing antibody i.p.); AR group (BN-->LEW, n = 10, recipients were treated with normal saline i.p.) and control group (LEW-->LEW, n = 6, recipients were treated with normal saline i.p.). The blood samples of recipients were drawn at Days 1, 3, 5 and 7 post-transplantation. The serum expressions of IL-15, OPN, PFP and GraB mRNA of recipients were detected by real-time PCR. Allograft tissues were analyzed by pathological assays. RESULTS: In comparison with other groups, the expressions of OPN, IL-15, PFP and GraB mRNA in AR group were gradually up-regulated and peaked at Day 5. The expressions of IL-15 mRNA in CsA and AB groups were 9685 +/- 1440 and 4346 +/- 741 respectively at Day 5 post-operation. It was significantly lower than that in AR group (17 022 +/- 2153, P < 0.01). The expression of IL-15 mRNA in AB group was significantly lower than that in CsA group (P < 0.01). The expressions of OPN mRNA in CsA and AB groups (13 226 +/- 1565 vs 19 112 +/- 2908) were both significantly lower than that in AR group (24 663 +/- 2449, P < 0.01). But the expression of OPN mRNA in AB group was higher than that in CsA group (P < 0.01). At Day 5 post-transplantation, both the expressions of PFP and GraB mRNA in AB and CsA groups was lower than that in AR group (P < 0.01). The pathological results showed that severe AR occurred at Day 7 post-transplantation in AR group and whereas the extent of rejection sign relieved in AB group. CONCLUSION: In early stage of AR of renal allograft in rats, the expressions of OPN, IL-15, PFP and GraB mRNA are up-regulated. Blocking IL-15/IL-15R pathway in early stage of AR can down-regulate the expressions of PFP and GraB mRNA.