IL-17 production elicited by allo-major histocompatibility complex class II recognition depends on CD25posCD4pos T cells.

BACKGROUND: Interleukin (IL)-17 is involved in autoimmune inflammatory disorders and naturally occurring CD25pos regulatory T cells were shown to promote IL-17 synthesis. Because IL-17 is overproduced in certain types of allograft rejection, it is important to characterize the cells responsible for IL-17 synthesis and to define how IL-17 is regulated during alloimmune responses. METHODS: Splenic CD4pos T cells were isolated from C57BL/6 mice and fractionated according to CD25 expression. T cells were stimulated by major histocompatibility complex class II-mismatched bone marrow-derived dendritic cells from bm12 mice, either immature or made mature by exposure to lipopolysaccharide. To track T cell populations, CD25negCD4pos and CD25posCD4pos were isolated from Thy1.1 and congenic Thy1.2 mice, respectively. Cell proliferation was quantified by CFSE dilution. IL-17-producing cells and FOXP3pos cells were enumerated by intracytoplasmic staining and cytokine levels in culture supernatants were measured by ELISA. RESULTS: Addition of CD25posCD4pos T cells to CD25negCD4pos T cells inhibited IL-2, interferon-[gamma], and IL-13 production but promoted IL-17 synthesis on stimulation by allogenic immature DC. In this setting, IL-17 originated from CD25intCD4posFOXP3neg memory T cells, which depend on IL-2 to produce IL-17. Alloreactive CD25negCD4pos T cells were also induced to produce IL-17 when stimulated by mature DC in the presence of CD25highCD4posFOXP3pos T cells. CONCLUSIONS: We conclude that (1) the cellular source of IL-17 during an antiallo major histocompatibility complex class II response depends on the maturation status of allogenic DC, (2) whereas suppressing Th1 and Th2 cytokine synthesis, naturally occurring regulatory T cells, allow IL-17 production by alloreactive CD4pos T cells.

Prospective Validation Obtained in a Similar Group of Patients and with Similar High Throughput Biological Tests Failed to Confirm Signatures for Prediction of Response to Chemotherapy and Survival in Advanced NSCLC: A Prospective Study from the European Lung Cancer Working Party.

AIM: Cisplatin doublets are standard 1st line treatment for advanced non-small cell lung cancer (NSCLC), without accurate predictor for response and survival, but important toxicity. Our aims were to identify predictive (for response) and prognostic (for survival) biological signatures in patients with NSCLC using messenger RNAs (mRNA) and miRNA expression. METHODS: Patients with pathologically proven untreated NSCLC, receiving 1st line cisplatin-vinorelbine and with an assessable lesion were eligible. A bronchial biopsy was lysed into Tripure Isolation Reagent on ice, snap frozen, and stored at -80°C. mRNA expression was analyzed using microarrays Agilent Technologies. miRNA expression was assessed using TaqMan Low Density Arrays (756 human miR panel, Applied Biosystems). Validation was performed by RT-PCR on the selected genes. Survival was measured from the registration date and response assessed by WHO criteria. RESULTS: Biopsies for transcriptomic analyses were obtained from 60 consecutive patients. No statistically significant differences were observed according to the main clinical characteristics, response rate (43 vs. 41%) or survival (median 25 vs. 29 months) between derivation and validation sets. In the derivation set (n = 38 patients), two mRNA and one miRNA predictive signatures for response were obtained. One mRNA and one miRNA prognostic signatures were derived from the first set, allowing an adequate distinction of patients with good and poor overall and progression-free survivals. None of these signatures could be validated in the validation set (n = 22 patients). CONCLUSION: In this prospective study with advanced NSCLC treated with cisplatin-vinorelbine, we were able to derive with high throughput techniques predictive and prognostic signatures based on transcriptomic analyses. However, these results could not be reproduced in an independent validation set. The role of miRNA and mRNA as predictive or prognostic factors remains a research topic and the use of high throughput technology in that context questionable. The ClinicalTrials.gov study identifier is NCT00864266 (www.clinicaltrials.gov).

Acute liver transplant rejection upon immunosuppression withdrawal in a tolerance induction trial: potential role of IFN-gamma-secreting CD8+ T cells.

We designed a pilot trial in cadaveric liver transplantation to determine whether induction with antithymocyte globulins (ATG) and sirolimus would allow immunosuppression withdrawal. Patients received ATG 3.75 mg/kg per day from day 1 to 5 after transplantation followed by sirolimus for 4 to 6 months. We monitored interleukin (IL)-7 serum levels, interferon (IFN)-gamma, and IL-2 mRNA accumulation in mixed leukocyte reaction and intragraft IFN-gamma mRNA expression. In the first three patients, immunosuppression discontinuation was followed by reversible acute rejection occurring on days 280, 246, and 163 posttransplantation, corresponding to days 140, 40, and 39 after drug withdrawal, respectively. At the time of rejection, blood CD8+ T-cells counts had returned to or above pretransplant levels in two of three patients, whereas CD4+ T-cell count remained low. IL-7 serum levels rose in all three patients in the first months after transplantation and IFN-gamma mRNA accumulated in mixed leukocyte reaction between recipient T cells and donor spleen cells at the time of rejection. High levels of IFN-gamma mRNA were consistently detected in liver biopsy performed at the time of rejection. In conclusion, lymphopenia-induced IL-7 production after induction with ATG and sirolimus might lead to emergence of IFN-gamma-secreting CD8+ T-cells responsible for acute rejection after immunosuppression withdrawal.