DMD is characterized by muscle inflammation due to higher levels of pro-inflammatory cytokines such as interleukin 1β (IL-1β). We have assessed the effect of a human IgG1κ monoclonal antibody (canakinumab (Ilaris®)) against IL-1β on the ability of human muscle cells to secrete the pro-inflammatory myokine IL-6.
Canakinumab is a strong candidate for therapeutic repurposing to treat DMD because it is already FDA approved for juvenile and adult autoinflammatory diseases. Unlike other IL-1 inhibitors, canakinumab is highly specific for the IL-1β ligand, has a longer half-life, and does not interfere with other IL-1-activated pathways. Following cell culture optimization and viability assays to assess toxicity, myoblasts were stimulated with IL-1β (10 ng/ml) for 48 hours in the presence of eight concentrations of canakinumab and IL-6 production was measured with an enzyme-linked immunosorbent assay. Incubation of canakinumab with IL-1β-stimulated myoblasts significantly reduced IL-6 production at concentrations of 1, 10, 100, 250, and 1000 nM relative to controls (p<0.001 for all doses), yielding an IC50 of 0.264 nM. On the other hand, canakinumab that was pre-bound to IL-1β and then administered in combination to myoblasts resulted in a higher inhibitory affinity with the IC50 reducing to 0.126 nM, less than half of the previous method.
This study also evaluated the effects of canakinumab in reducing IL-6 production in myotubes, the terminally differentiated and functional muscle cells. The ELISA assay showed significant reduced levels of IL-6 after 30 min IL-1β (10 ng/ml) coincubation with canakinumab (10 nM) (p<0.001).
This study reveals that canakinumab is a potent inhibitor of IL-1β-stimulated IL-6 production in muscle cells (myoblasts and myotubes). These results align with previously published pre-clinical work in mdx mice and support further investigation into the clinical utility of repositioning canakinumab for treatment of DMD.