P168 Selective inhibition of multiple cytokines: A novel therapeutic strategy for immune-mediated diseases

Abstract

Introduction Directed therapy against cytokines or their receptors has been a valid therapeutic approach for various immune-mediated diseases. However, increasing reports suggest that more than one cytokine need to be inhibited in immune-mediated diseases. The limitation to the current strategy is the lack of effective blocking monoclonal antibodies (MAb) against each cytokine/cytokine receptor or the cost and inconvenience of combining more than one mAb for such therapeutic regimen. As a first attempt to inhibit multiple cytokines, we focused on targeting the gc-family cytokines (IL-2, -4, -7, -9, 15, and -21) that play pivotal roles in innate and adaptive immune responses and have been suggested to be involved in many immune-mediated diseases. As these cytokines use the common gamma chain (gc) for signal transduction, targeting the gc receptor is a rationale strategy to block the function of these cytokines. However, so far no efficiently blocking mAb against this receptor has been available. Furthermore, kinase inhibitors that target Jak3 that is uniquely associated with the gc receptor have shown non-specific effect on Jak1 and Jak2 which results in serious side effects. As an alternative to this strategy, Bioniz has developed antagonist peptides that specifically target gc receptor. However, instead of completely blocking the functions of all six cytokines that utilize this receptor, these peptides inhibit select members of this cytokine family. To demonstrate the efficacy of this novel strategy in treating immune-mediated diseases, Bioniz has focused on an orphan MS-like neurological disease called HAM/TSP (HTLV-I HTLV-I Associated Myelopathy/Tropical Spastic Paraparesis) in which patients exhibit a continuous elevated immune response against the virus HTLV-I. It has been shown that IL-2, IL-9, and IL-15 are critical in the development and pathogenesis of HAM/TSP. Thus, a rationale therapeutic approach for HAM/TSP is to inhibit IL-2, IL-9, and IL-15 simultaneously. Methods Cell proliefration assays were performed using a murine cell line CTLL2, a human cell line NK92, and HAM/TSP periperhal T-cells. Flow cytometry analysis was conducted on HAM/TSP cells to monitor the expression of various T-cell markers during the ex vivo culture. The phosphorylation of signal transducer molecule STAT5 was tested in Westen Blot and Flow Cytometry assays. Results Bioniz’s lead peptide, BNZ-g inhibits IL-2, IL-9 and IL-15 as determined in cell proliferation assays. Incubation with this peptide diminished the IL-2-induced STAT-5 phosphorylation in CTLL cells. Furthermore, BNZ-g inhibited the T-cell proliferation of HAM/TSP patient peripheral blood in ex vivo assays. BNZ-g also reduced the CD25 expression and STAT5 phosphorylation in HAM/TSP T-cells, markers of T-cell and gc receptor activation, respectively. Conclusion Other lines of evidence suggested that BNZ-g blocks only select members of the gc cytokines, including IL-2, IL-9, and IL-15, but excluding IL-4 and IL-7 and therefore, offers a rationale treatment strategy for HAM/TSP. More broadly, selective and simultaneous inhibition of multiple cytokines is a novel therapeutic approach that would open up vast possibilities in various immune-mediated diseases.