IL-21 induces in vivo immune activation of NK cells and CD8+ T cells in patients with metastatic melanoma and renal cell carcinoma

PURPOSE: Human interleukin-21 (IL-21) is a class I cytokine previously reported in clinical studies on immune responsive cancers. Here we report the effects of systemic IL-21 therapy on the immune system in two phase 1 trials with this novel cytokine. EXPERIMENTAL DESIGN: Recombinant IL-21 was administered by intravenous bolus injection at dose levels from 1 to 100 microg/kg using two planned treatment regimens: thrice weekly for 6 weeks (3/week); or once daily for five consecutive days followed by nine dose-free days (5 + 9). The following biomarkers were studied in peripheral blood mononuclear cells (PBMC) during treatment: phosphorylation of STAT3, alterations in the composition of leukocyte subsets, ex vivo cytotoxicity, expression of effector molecules in enriched CD8(+) T cells and CD56(+) NK cells by quantitative RT-PCR, and gene array profiling of CD8(+) T cells. RESULTS: Effects of IL-21 were observed at all dose levels. In the 5 + 9 regimen IL-21 induced a dose dependent decrease in circulating NK cells and T cells followed by a return to baseline in resting periods. In both CD8(+) T cells and CD56(+) NK cells we found up-regulation of perforin and granzyme B mRNA. In addition, full transcriptome analysis of CD8(+) T cells displayed changes in several transcripts associated with increased cell cycle progression, cellular motility, and immune activation. Finally, cytotoxicity assays showed that IL-21 enhanced the ability of NK cells to kill sensitive targets ex vivo. CONCLUSIONS: IL-21 was biologically active at all dose levels administered with evidence of in vivo NK cell and CD8(+) T cell activation

Expression of IL-21 receptor in synovial tissue and blood of patients with rheumatoid arthritis

Background and objectives: Cytokines regulate a broad range of inflammatory pathways in the pathogenesis of Rheumatoid Arthritis (RA), and cytokine blockade against tumour necrosis factor α and IL-6 has offered substantial advances in the treatment of articular inflammation. However, a large proportion of patients will not respond or exhibit only a partial response to treatment and new therapies are thus required. IL-21 is a member of the four-α-helix bundle family of cytokines that mediates pleiotropic effects through the IL-21 receptor (IL-21R). Since potency of IL-21 is mainly dependent on presence and abundance of its receptor on different cells types, the objective of this study was to characterise expression of IL-21R in the synovium and blood of patients with RA. <p/>Materials and methods: Immunohistochemistry for IL-21R was carried out on synovial tissue samples derived by arthroplasty from patients with RA (n=5) obtained from the Institute of Infection, Immunity and Inflammation Research Tissue Bank. Mononuclear cells were separated out from peripheral blood (PBMC) of 10 RA patients or 3 healthy controls on a density gradient using Histopaque (Sigma) and analysed by flow cytometry for IL-21R expression on T cells (CD3/CD4/CD8), B cells (CD19/CD27) and NK cells (CD16/CD56). <p/>Results: Expression of IL-21R was detected in 5/5 synovial RA tissues. The IL-21R+ cells were located in the synovial intimal and sublining layers and in lymphoid aggregates. Flow cytometric analysis on blood PBMC revealed that IL-21R is highly expressed on both CD4+ (73.04%, 12.58 MFI) and CD8+ (50.88%, 13.69 MFI) T cells, as well as on a proportion of NK cells (73.83%, 19.15 MFI) in RA patients. On B cells, IL-21R expression was higher on the CD27- fraction of naïve B cells (95.19%, 37.02 MFI), with lower expression on the CD27+ memory B cells (15.2%, 32.22 MFI). <p/>Conclusions: Our results show increased expression of IL-21R in established RA synovial tissue and peripheral blood, and indicate that targeting of the IL-21/IL-21R pathway may be a valid therapeutic strategy for the treatment of RA

Evaluating IL-21 as a Potential Therapeutic Target in Crohn’s Disease

Background and Aim. Interleukin-21 (IL-21) is primarily a T cell-derived cytokine; it is upregulated in patients with Crohn’s Disease (CD) and could be a potential new therapeutic target in CD. Methods. In human material, IL-21 and IL-21R expression was investigated by in situ hybridization (ISH) and immunohistochemistry (IHC) in noninflammatory bowel disease (non-IBD) controls and patients with CD. The pathologic role of IL-21 was examined in murine models of T cell-dependent and T cell-independent colitis, either with a neutralizing monoclonal antibody against IL-21 or with the transfer of CD4+CD45RBhighIL-21R−/− T cells. Colonic pathology was examined by endoscopy, histopathology, IHC, ELISA, and Luminex. Results. In the human intestine, IL-21 and IL-21R mRNA and protein-expressing cells were observed in the mucosa, in lymphoid aggregates of submucosa in non-IBD controls, and in lymphoid aggregates of muscularis externa in patients with CD. IL-21 expression was most abundant in germinal centers (GCs) of the lymphoid aggregates, and IL-21R expression assessed semiquantitatively, was significantly higher in patients with CD compared to non-IBD controls. Following prophylactic and interventive anti-IL-21 mAb treatment in the adoptive transfer (AdTr) model, clinical and pathological parameters were significantly reduced. The most persistent finding was a reduction in colonic infiltrating neutrophils. As well, Rag2−/− mice receiving CD4+CD45RBhighIL-21R−/− T cells developed less severe colitis compared to Rag2−/− mice receiving CD4+CD45RBhighIL-21R+/+ T cells. No effect of reduced IL-21 signalling was observed in T cell-independent colitis. Conclusion. Our study shows that patients with CD have significant expression of IL-21 and IL-21R in the gut. As well, we show that neutralization of IL-21 in experimental T cell-driven colitis is associated with a reduction in clinical and pathological findings. This amelioration seems to be associated with a reduction in colon-infiltrating neutrophils