The present disclosure relates to methods and compositions useful for initiating and propagating ICOS-mediated signaling. In particular, the present disclosure provides three peptide motifs which promote ICOS binding and whose ablation leads to modulated ICOS signaling and modulated signaling mediated by TBK1, IRF4, IKKβ, or TBKBP1. The binding of these peptide motifs or the addition of such motifs as co-stimulatory agents leads to modulated immune responses, and provides new and unexpected therapies for neurodegenerative, autoimmune, metabolic, cancer inflammatory, or immunodeficiency conditions, diseases, or disorders.